Human variant glucose-6-phosphate transporter is active in microsomal transport

Glycogen storage disease type lb (GSD-lb) is caused by deficiencies in the glucose-6-phosphate transporter (G6PT), which works together with glucose-6-phosphatase to maintain glucose homeostasis. In humans, there are two alternatively spliced transcripts, G6PT and variant G6PT (vG6PT), differing by the inclusion of a 66-bp exon-7 sequence in vG6PT. We have previously shown that the G6PT protein functions as a microsomal glucose-6-phosphate (G6P) transporter, which is anchored to the endoplasmic reticulum by ten transmembrane helices. Here, we demonstrate that vG6PT is also active in microsomal G6P transport. The additional 22 amino acids in vG6PT is predicted to constitute a part of the luminal loop 4. Our data indicate that this loop plays no vital role in microsomal G6P transport. Further, we show that G6PT mRNA is expressed in all organs and tissues examined, but that the vG6PT transcript is expressed exclusively in the brain, heart, and skeletal muscle. These results raise the possibility that mutations in exon-7 of the G6PT gene, which would not perturb glucose homeostasis, might have other deleterious effects.

One-step hysteroscopic removal of sinking submucous myoma in two infertile patients

OBJECTIVE

To report one-step resectoscopic removal of submucous myomas that were pushed back into the muscular layer by increased intrauterine pressure during hysteroscopic procedures.

DESIGN

Case report.

SETTING

Kawasaki Municipal Hospital, Kawasaki, Japan.

PATIENT(S)

Two infertile women presenting with menorrhagia in whom submucous myoma with a broad base was diagnosed.

INTERVENTION(S)

One patient was pretreated with GnRH agonist for 4 months; the other patient did not receive this treatment. Resectoscopic myomectomies were performed under close sonographic monitoring.

MAIN OUTCOME MEASURE(S)

Clinical symptoms and conception status.

RESULT(S)

Tumor sinking occurred during the hysteroscopic procedures, but complete resectoscopic removal of the submucous myomas was achieved under sonographic and hysteroscopic visualization. One patient experienced hyponatremia but recovered after conservative treatment. Both patients conceived after myoma removal.

CONCLUSION(S)

Sinking myomas, which may cause infertility, can be removed with a one-step hysteroscopic procedure. Sinking of submucous myomas during hysteroscopy might be caused by pretreatment with GnRH agonist and by increased intrauterine pressure during hysteroscopy. We recommend that intrauterine pressure be <45 mmHg, equivalent to hanging a bag of fluid under gravity control 70 cm above the patient's uterus, at the beginning of operations for sinking myomas.

Thalidomide and its analogs overcome drug resistance of human multiple myeloma cells to conventional therapy

Although thalidomide (Thal) was initially used to treat multiple myeloma (MM) because of its known antiangiogenic effects, the mechanism of its anti-MM activity is unclear. These studies demonstrate clinical activity of Thal against MM that is refractory to conventional therapy and delineate mechanisms of anti-tumor activity of Thal and its potent analogs (immunomodulatory drugs [IMiDs]). Importantly, these agents act directly, by inducing apoptosis or G1 growth arrest, in MM cell lines and in patient MM cells that are resistant to melphalan, doxorubicin, and dexamethasone (Dex). Moreover, Thal and the IMiDs enhance the anti-MM activity of Dex and, conversely, are inhibited by interleukin 6. As for Dex, apoptotic signaling triggered by Thal and the IMiDs is associated with activation of related adhesion focal tyrosine kinase. These studies establish the framework for the development and testing of Thal and the IMiDs in a new treatment paradigm to target both the tumor cell and the microenvironment, overcome classical drug resistance, and achieve improved outcome in this presently incurable disease.

The N-terminal domain of the Caulobacter crescentus CgtA protein does not function as a guanine nucleotide exchange factor

The Caulobacter crescentus GTP binding protein CgtA is a member of the Obg/GTP1 subfamily of monomeric GTP binding proteins. In vitro, CgtA displays moderate affinity for both GDP and GTP, and rapid exchange rate constants for either nucleotide. One possible explanation for the observed rapid guanine nucleotide exchange [corrected] rates is that CgtA is a bimodal protein with a C-terminal GTP binding domain and an N-terminal GEF domain. In this study we demonstrate that although the N-terminus of CgtA is required for function in vivo, this domain plays no significant role in the guanine nucleotide binding, exchange or GTPase activity.

GDP-fucose: beta-galactoside alpha1,2-fucosyltransferase, MFUT-II, and not MFUT-I or -III, is induced in a restricted region of the digestive tract of germ-free mice by host-microbe interactions and cycloheximide

A shift from sialylation to fucosylation of mucosal glycoconjugates occurred in the mammalian digestive tract in the weaning period, but mice under germ-free conditions were found to express both fucosyl GM1 (FGM1) and fucosyl asialo GM1 (FGA1) in the stomach, cecum and colon, but not in the small intestine. By host-microbe interactions and administration of cycloheximide, FGA1 was quickly induced in the small intestine, but the concentrations of fucosylated glycolipids in the other regions were not altered significantly. Their expression coincided with the activity of GDP-fucose:GA1 alpha(1, 2)-fucosyltransferase (alpha1,2-FT), and we isolated a cDNA with an open reading frame encoding the murine alpha1,2-FT (MFUT-II) of 347 amino acids with a predicted molecular mass of 39.21 kDa. The intraperitoneal injection of cycloheximide induced the mRNA and activity of alpha1,2-FT (MFUT-II) in the small intestine of germ-free mice, whereas no change in the mRNA or activity was observed in the stomach, cecum and colon, indicating that expression of FGA1 in response to microbial colonization or cycloheximide is transcriptionally regulated in a restricted region of the murine digestive tract. At 24 h after the administration of cycloheximide, FGA1 was preferentially produced in the upper half of the duodenal microvilli.

Direct measurements of constrained brownian motion of an isolated sphere between two walls

We report the results of direct measurements, using video microscopy in combination with optical tweezers, of constrained diffusion of an isolated uncharged PMMA sphere in a density-matched fluid confined between two parallel flat walls. Our experimental methodology allows us to study the hindered diffusion of the sphere as an explicit function of its distance from the walls, without interference from sedimentation or from electrostatic interaction between the particle and the walls. The measured diffusion coefficients are used to test the predictions of the wall drag effect predicted by several approximate theoretical analyses. We find a quantitative agreement with the behavior predicted using a hydrodynamic analysis that independently superimposes the wall drag effects arising from each wall. Our results imply, indirectly, that neglect of multiple interactions with the colloid sphere of the perturbations of the pressure and velocity fields induced by each wall leads to an underestimate of the influence of the wall on the drag force experienced by the particle.

Cytochrome c release and apoptosis induced by mitochondrial targeting of nuclear orphan receptor TR3

TR3, an immediate-early response gene and an orphan member of the steroid-thyroid hormone-retinoid receptor superfamily of transcription factors, regulates apoptosis through an unknown mechanism. In response to apoptotic stimuli, TR3 translocates from the nucleus to mitochondria to induce cytochrome c release and apoptosis. Mitochondrial targeting of TR3, but not its DNA binding and transactivation, is essential for its proapoptotic effect. Our results reveal a mechanism by which a nuclear transcription factor translocates to mitochondria to initiate apoptosis.

Transient state of chiral recognition in a binary mixture of cyclodextrins in capillary electrophoresis

The transient state (as the defined point where no enantioseparation is obtained in a dual chiral selector system) of chiral recognition of aminoglutethimide in a binary mixture of neutral cyclodextrins (CDs) was studied by capillary electrophoresis (CE). The following three dual selector systems were used: alpha-cyclodextrin (alpha-CD) and beta-cyclodextrin (beta-CD); alpha-CD and heptakis(di-O-methyl-beta-cyclodextrin) (DM-beta-CD); alpha-CD and heptakis(tri-O-methyl-beta-cyclodextrin) (TM-beta-CD). The S-(-) enantiomer of the analyte was more strongly retained in the presence of either alpha-CD or TM-beta-CD at pH 2.5, 100 mM phosphate buffer, while the R-(+) enantiomer was more strongly retained in the presence of either beta-CD or DM-beta-CD. In the more simple case, the elution order is invariably kept if the enantiomers have the same elution order in either one of the two hosts of the binary mixture. In contrast, the elution order may be switched by varying the concentration ratio of two hosts that produce opposite elution order for this particular analyte. In such a dual selector system, the enantioselectivity will disappear at the transient state at a certain ratio of host1:host2. Moreover, the migration times of the two enantiomers with host, alone (diluted in buffer) is approximately equal to the migration times at the corresponding concentration of host2 alone (diluted in buffer), where the ratio of concentrations of host1:host2 is the same as in the binary mixture at the transient state. As found by nuclear magnetic resonance experiments, the analyte is forming a 1:1 complex with either one of the CDs applied. From this finding, a theoretical model based on the mobility difference of the two enantiomers was derived that was used to simulate the transient state.

[Iodine-125 labeled monoclonal antibody 3H11: in radioimmunoguided surgery for primary gastric cancer]

OBJECTIVE

To evaluate the clinical usefulness of iodine-125 labeled monoclonal antibody (MAb) 3H11 in radioimmunoguided surgery (RIGS) for patients with gastric cancer.

METHODS

Thirty-five patients with primary gastric cancer were enrolled. Via endoscopy, iodine-125 labeled MAb 3H11 was injected into submucosa around the tumor. All patients underwent surgery 4 to 11 days after administration. Intraoperative radioimmunodetection was performed using a hand-held gamma-detecting probe. The counts of target sites were obtained, and tumor-to-normal tissue (T/NT) ratios were calculated. The T/NT ratio of 3.5:1 was taken as the lowest threshold value of positive gastric wall infiltration, and 3.0:1 for lymph node metastasis. Serial sections of those RIGS-positive lymph nodes, which were originally diagnosed as negative by routine histology, were made. Immunohistochemical staining was performed to detect the existence of lymphatic micrometastasis.

RESULTS

Of thirty-five patients, 33 underwent RIGS successfully. The accuracy rate in detecting tumor infiltration of the incision margins was 97.0%, and the specificity 98.5%. In the group of patients with an interval of 6 to 8 days between injection and operation (n = 25), the RIGS results were satisfying. For the detection of lymphatic metastasis, the sensitivity of RIGS was 83.6%, the specificity 95.0%, and the accuracy 91.3%. The existence of lymphatic micrometastasis were verified immunohistochemically in 52.6% (10/19) of those RIGS positive but histologically negative lymph nodes.

CONCLUSION

This study validates the use of iodine-125 labeled monoclonal antibody 3H11 for the intraoperative detection of carcinomatous lesions in gastric cancer.

Quantitative assessment of the normal cerebral microvasculature by endothelial barrier antigen (EBA) immunohistochemistry: application to focal cerebral ischemia

Cerebrovascular endothelium participates importantly in the pathophysiology of ischemic injury. Endothelial barrier antigen (EBA) is a protein located in the luminal plasma membrane of normal central and peripheral nervous-system endothelium. In this study, we assessed the sensitivity and specificity of EBA as a quantitative marker of normal endothelium and characterized alterations of EBA immunohistochemistry following focal cerebral ischemia. Anesesthetized, non-ischemic control rats (N=6) were studied. Other animals (N=5) received 90 min of middle cerebral artery occlusion (MCAo) followed by 3-day survival. Brains were prepared by perfusion-fixation and paraffin-embedding. For EBA immunohistochemistry, a monoclonal antibody (1:2000 dilution) was used. Adjacent sections were reacted for activated microglia by isolectin immunochemistry. Morphometric image-analysis was carried out in standardized microscopic fields. In control brains, pial and parenchymal blood vessels of all sizes were distinctly and selectively immunolabeled for EBA; background staining was absent. EBA-positive vascular profiles occupied 4.3+/-0.36% (mean+/-S.D.) of the microscopic field. The mean area of each identified profile was 51+/-13 micromter(2). The low coefficients of variation for both numbers of profiles (17%) and fractional areas (8%) denoted high inter-animal consistency. In brains with prior MCAo, numbers of EBA-immunoreactive vascular profiles in infarcted cortex and striatum were reduced by 39 and 46%, respectively, and their fractional areas were decreased by 63 and 76%, respectively, compared to contralateral hemisphere. Activated microglia were prominent in zones of frank infarction and in adjacent paramedian cortex; the latter region, however, showed normal-appearing EBA-immunostaining. EBA-immunohistochemistry provides a sensitive and specific index of normal cerebrovascular endothelial structures of all sizes. The technique lends itself well to quantitative morphometry and is applicable to perfusion-fixed paraffin-embedded material. EBA immunoreactivity declines in zones of ischemic infarction.

Comprehensive analyses of prostate gene expression: convergence of expressed sequence tag databases, transcript profiling and proteomics

Several methods have been developed for the comprehensive analysis of gene expression in complex biological systems. Generally these procedures assess either a portion of the cellular transcriptome or a portion of the cellular proteome. Each approach has distinct conceptual and methodological advantages and disadvantages. We have investigated the application of both methods to characterize the gene expression pathway mediated by androgens and the androgen receptor in prostate cancer cells. This pathway is of critical importance for the development and progression of prostate cancer. Of clinical importance, modulation of androgens remains the mainstay of treatment for patients with advanced disease. To facilitate global gene expression studies we have first sought to define the prostate transcriptome by assembling and annotating prostate-derived expressed sequence tags (ESTs). A total of 55000 prostate ESTs were assembled into a set of 15953 clusters putatively representing 15953 distinct transcripts. These clusters were used to construct cDNA microarrays suitable for examining the androgen-response pathway at the level of transcription. The expression of 20 genes was found to be induced by androgens. This cohort included known androgen-regulated genes such as prostate-specific antigen (PSA) and several novel complementary DNAs (cDNAs). Protein expression profiles of androgen-stimulated prostate cancer cells were generated by two-dimensional electrophoresis (2-DE). Mass spectrometric analysis of androgen-regulated proteins in these cells identified the metastasis-suppressor gene NDKA/nm23, a finding that may explain a marked reduction in metastatic potential when these cells express a functional androgen receptor pathway.

Core protein phosphorylation modulates pregenomic RNA encapsidation to different extents in human and duck hepatitis B viruses

To clarify the role of core protein phosphorylation in pregenomic-RNA encapsidation of human and duck hepatitis B viruses (HBV and DHBV, respectively), we have examined the phosphorylation states of different forms of intracellular HBV core protein and the phenotypic effects of mutations in the phosphorylation sites of HBV and DHBV core proteins. We show that HBV core protein is phosphorylated to similar extents in the form of protein dimers and after further assembly in pregenomic RNA-containing capsids. Individual and multiple substitutions of alanine and aspartic acid for serine in the phosphorylation sites of HBV core protein resulted in site-specific and synergistic effects on RNA encapsidation, ranging from 2-fold enhancement to more than 10-fold inhibition. Core protein variants with mutations in all phosphorylation sites exhibited dominant-negative effects on RNA encapsidation by wild-type protein. The results suggest that the presence of phosphoserine at position 162 of HBV core protein is required for pregenomic-RNA encapsidation, whereas phosphoserine at position 170 optimizes the process and serine might be preferable in position 155. Examination of the pregenomic-RNA-encapsidating capacities of DHBV core protein variants, in which four phosphorylation sites were jointly mutated to alanine or aspartic acid, suggests that phosphorylation of DHBV core protein at these sites may optimize pregenomic-RNA encapsidation but that its impact is much less profound than in the case of HBV. The possible mechanisms by which RNA encapsidation may be modulated by core protein phosphorylation are discussed in the context of the observed differences between the two viruses.

Separation of drug enantiomers by capillary electrophoresis in the presence of neutral cyclodextrins

This is a selected review, highlighting our results obtained in an extended screening program ("The German-Chinese Drug Screening Program"), with a focus on a set of original data obtained with heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TM-beta-CD) as the chiral solvating agent (CSA). The enantioseparation of 86 drugs by capillary zone electrophoresis in the presence of this CSA was successful for 47 drugs. The migration separation factors (alpham) and the migration retardation factors (Rm) were compared with those found for native beta-cyclodextrin (beta-CD). The patterns thus obtained were also compared with those observed for hexakis(2,3,6-tri-O-methyl)-alpha-CD (TM-alpha-CD) and octakis(2,3,6-tri-O-methyl)-gamma-CD (TM-gamma-CD), respectively. From the statistical data, it can be concluded that there is a remarkable influence of the analyte structure on the electrophoretic data. A substructure 4H was found in the analyte structure that has a significant influence on the analytes' behaviour. Thus, analytes bearing the substructure 4H do not only have a strong affinity to the CDs but also a high rate of success of chiral separation in all systems reviewed. In light of this, the different ring sizes of native cyclodextrins (alpha-, beta- and gamma-CD) readily explain their behaviour towards a limited test set of chiral drugs. Sterical considerations point to the significance of side-on-binding versus inclusion in the cavity of the host. In addition to the findings from the screening program, numerous references to the literature are given.

Novel cathepsin D inhibitors block the formation of hyperphosphorylated tau fragments in hippocampus

Lysosomal disturbances may be a contributing factor to Alzheimer's disease. We used novel compounds to test if suppression of the lysosomal protease cathepsin D blocks production of known precursors to neurofibrillary tangles. Partial lysosomal dysfunction was induced in cultured hippocampal slices with a selective inhibitor of cathepsins B and L. This led within 48 h to hyperphosphorylated tau protein fragments recognized by antibodies against human tangles. Potent nonpeptidic cathepsin D inhibitors developed using combinatorial chemistry and structure-based design blocked production of the fragments in a dose-dependent fashion. Threshold was in the submicromolar range, with higher concentrations producing complete suppression. The effects were selective and not accompanied by pathophysiology. Comparable results were obtained with three structurally distinct inhibitors. These results support the hypothesis that cathepsin D links lysosomal dysfunction to the etiology of Alzheimer's disease and suggest a new approach to treating the disease.

Melting transition in a quasi-two-dimensional colloid suspension: influence of the colloid-colloid interaction

We report the results of a study, using digital video microscopy, of the melting transition in a quasi-two-dimensional suspension of uncharged silica spheres. This system was chosen to further test the dependence of the two-dimensional melting transition on the functional form of the colloid-colloid interaction. Our experimental data show that the solid phase undergoes a first order transition directly to the liquid phase. The system studied yields no evidence of the existence of a hexatic phase interpolating between the solid and liquid phases in the melting process.

A low-voltage droplet charging circuit with simulative cell-sorting function for flow cytometer-cell sorter

BACKGROUND

Flow cytometer cell sorters have become important tools in many biological laboratories. Commercial electrically-deflected cell sorters that deflect wanted cells in electrically charged droplets need high-voltage amplifiers which are expensive and difficult to obtain. Effort was made to build an alternative droplet charging circuit with low-voltage amplifiers that are much easier to get and have more reasonable price.

METHODS

A low-voltage charging circuit was designed. Every time a cell was to be separated, a pair of complementary charging pulses were produced: one was positive and the other was negative with equal amplitude. These were enlarged by two low-voltage charging amplifiers to drive two charging electrodes respectively.

RESULTS

Due to the effect of addition, the voltage between the two electrodes was double as high as the output of either amplifier. The result of test experiment proved that the cell sorter with low-voltage amplifiers, which was cheaper and easier to obtain, could separate cells as efficiently as the instrument with high-voltage ones that were more expensive and more difficult to make. In addition, a simulative cell-sorting function was provided.

CONCLUSIONS

This low-voltage, easily-built and low-price charging circuit for flow cytometer cell sorter is a good alternative to the commonly used high-voltage one, especially to researcher who hopes to build his own personal instrument.

Soluble CD14 levels in the serum, synovial fluid, and cerebrospinal fluid of patients with various stages of Lyme disease

Levels of circulating soluble CD14 (sCD14) in patients with various stages of Lyme disease (LD) were examined. Patients with early or untreated late LD had significantly higher levels of sCD14 than did healthy controls (P=.0001 and .0007, respectively); levels returned to normal within 3 months after antibiotic therapy. Patients with persistent posttreatment symptoms of LD had sCD14 levels equivalent to those of healthy controls. Differences in the serum sCD14 levels in patients with various stages of LD are likely to be directly correlated with differences in bacterial burden, suggesting that posttreatment symptoms may not require continued presence of the organism. sCD14 levels in the cerebrospinal fluid (CSF) of patients with any stage of LD were no different from those of control subjects. Levels of synovial fluid sCD14 from patients with Borrelia burgdorferi in their joints were elevated, compared with levels in normal serum, and may play a role in the pathogenesis of arthritis.

PART-1: a novel human prostate-specific, androgen-regulated gene that maps to chromosome 5q12

Genes regulated by androgenic hormones are of critical importance for the normal physiological function of the human prostate gland, and they contribute to the development and progression of prostate carcinoma. We used cDNA microarrays containing 1500 prostate-derived cDNAs to profile transcripts regulated by androgens in prostate cancer cells. This study identified a novel gene that we have designated PART-1 (prostate androgen-regulated transcript 1), which exhibited increased expression upon exposure to androgens in the LNCaP prostate cancer cell line. Northern analysis demonstrated that PART-1 is highly expressed in the prostate gland relative to other normal human tissues and is expressed as different transcripts using at least three different polyadenylation signals. The PART-1 cDNA and putative protein are not significantly homologous to any sequences in the nonredundant public sequence databases. Cloning and analysis of the putative PART-1 promoter region identified a potential binding site for the homeobox gene PBX-la, but no consensus androgen response element or sterol-regulatory element binding sites were identified. We used a radiation hybrid panel and fluorescence in situ hybridization to map the PART-1 gene to chromosome 5q12, a region that has been suggested to harbor a prostate tumor suppressor gene. These results identify a new gene involved in the androgen receptor-regulated gene network of the human prostate that may play a role in the etiology of prostate carcinogenesis.

Orphan receptor COUP-TF is required for induction of retinoic acid receptor beta, growth inhibition, and apoptosis by retinoic acid in cancer cells

Retinoic acid receptor beta (RARbeta) plays a critical role in mediating the anticancer effects of retinoids. Expression of RARbeta is highly induced by retinoic acid (RA) through a RA response element (betaRARE) that is activated by heterodimers of RARs and retinoid X receptors (RXRs). However, RARbeta induction is often lost in cancer cells despite expression of RARs and RXRs. In this study, we provide evidence that orphan receptor COUP-TF is required for induction of RARbeta expression, growth inhibition, and apoptosis by RA in cancer cells. Expression of COUP-TF correlates with RARbeta induction in a variety of cancer cell lines. In addition, stable expression of COUP-TF in COUP-TF-negative cancer cells restores induction of RARbeta expression, growth inhibition, and apoptosis by RA, whereas inhibition of COUP-TF by expression of COUP-TF antisense RNA represses the RA effects. In a transient transfection assay, COUP-TF strongly induced transcriptional activity of the RARbeta promoter in a RA- and RARalpha-dependent manner. By mutation analysis, we demonstrate that the effect of COUP-TF requires its binding to a DR-8 element present in the RARbeta promoter. The binding of COUP-TF to the DR-8 element synergistically increases the RA-dependent RARalpha transactivation function by enhancing the interaction of RARalpha with its coactivator CREB binding protein. These results demonstrate that COUP-TF, by serving as an accessory protein for RARalpha to induce RARbeta expression, plays a critical role in regulating the anticancer activities of retinoids.

The prevalence of C677T mutation in the methylenetetrahydrofolate reductase gene and its association with venous thrombophilia in Taiwanese Chinese

C677T mutation of the methylenetetrahydrofolate reductase gene remains a controversial risk factor for venous thrombosis in Whites. The prevalence of methylenetetrahydrofolate reductase C677T genotype and its association with vascular thrombosis are not well established in Chinese population. We conducted a case-control study to investigate the prevalence of methylenetetrahydrofolate reductase C677T gene mutation and its association with venous thrombophilia in Taiwanese Chinese. The subjects consisted of 112 venous thrombophilic patients and 125 healthy controls, with similar age (p=0.08) and sex (p=0.58). The prevalent rates of C/T heterozygote were 32.8 and 44.6%; whereas those of T/T homozygote were 6.4 and 8.0% in the controls and patients, respectively. Neither C/T heterozygote (odds ratio, 1.7; 95% confidence interval, 1.0-3.0, p=0.05] nor T/T homozygote (odds ratio, 1.4; 95% confidence interval, 0.5-4.0, p=0.5) was significantly associated with venous thrombosis. Even when only subjects (52 patients and 107 controls) with normal inhibitor protein levels were analyzed, the association of T/T homozygote with venous thrombosis remained insignificant (p=0.06) with an odds ratio (95% confidence interval) of 3.4 (0.99-11.7). We concluded that, in Taiwanese Chinese, methylenetetrahydrofolate reductase C677T mutation is a common genetic mutation, but T/T homozygote is not a significant risk factor for venous thrombophilia.

Correction of glycogen storage disease type 1a in a mouse model by gene therapy

Glycogen storage disease type 1a (GSD-1a), characterized by hypoglycemia, liver and kidney enlargement, growth retardation, hyperlipidemia, and hyperuricemia, is caused by a deficiency in glucose-6-phosphatase (G6Pase), a key enzyme in glucose homeostasis. To evaluate the feasibility of gene replacement therapy for GSD-1a, we have infused adenoviral vector containing the murine G6Pase gene (Ad-mG6Pase) into G6Pase-deficient (G6Pase(-/-)) mice that manifest symptoms characteristic of human GSD-1a. Whereas <15% of G6Pase(-/-) mice under glucose therapy survived weaning, a 100% survival rate was achieved when G6Pase(-/-) mice were infused with Ad-mG6Pase, 90% of which lived to 3 months of age. Hepatic G6Pase activity in Ad-mG6Pase-infused mice was restored to 19% of that in G6Pase(+/+) mice at 7-14 days post-infusion; the activity persisted for at least 70 days. Ad-mG6Pase infusion also greatly improved growth of G6Pase(-/-) mice and normalized plasma glucose, cholesterol, triglyceride, and uric acid profiles. Furthermore, liver and kidney enlargement was less pronounced with near-normal levels of glycogen depositions in both organs. Our data demonstrate that a single administration of a recombinant adenoviral vector can alleviate the pathological manifestations of GSD-1a in mice, suggesting that this disorder in humans can potentially be corrected by gene therapy.

Hyperglycemia triggers massive neutrophil deposition in brain following transient ischemia in rats

Myeloperoxidase (MPO) immunohistochemistry was used to ascertain the role of polymorphonuclear leukocytes in hyperglycemia-induced accentuation of brain injury after transient ischemia. Rats received 12.5 min of normothermic global cerebral ischemia by bilateral carotid occlusion plus hypotension. Hyperglycemia was induced before ischemia by intraperitoneal dextrose administration. Quantitative MPO immunohistochemistry was performed at 24 h and 3 days postischemia. Brains of normoglycemic-ischemic animals contained almost no MPO activity. By contrast, striking numbers of MPO-positive cells were present in brains studied 24 h after hyperglycemic ischemia, both within pial and parenchymal vessels and within the parenchyma. MPO deposition tended to subside at 3 days. These results indicate that hyperglycemia triggers the early, massive deposition of neutrophils in the postischemic brain--an event that may contribute to exacerbation of injury.

Cyclin D1 is required for transformation by activated Neu and is induced through an E2F-dependent signaling pathway

The neu (c-erbB-2) proto-oncogene encodes a tyrosine kinase receptor that is overexpressed in 20 to 30% of human breast tumors. Herein, cyclin D1 protein levels were increased in mammary tumors induced by overexpression of wild-type Neu or activating mutants of Neu in transgenic mice and in MCF7 cells overexpressing transforming Neu. Analyses of 12 Neu mutants in MCF7 cells indicated important roles for specific C-terminal autophosphorylation sites and the extracellular domain in cyclin D1 promoter activation. Induction of cyclin D1 by NeuT involved Ras, Rac, Rho, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38, but not phosphatidylinositol 3-kinase. NeuT induction of the cyclin D1 promoter required the E2F and Sp1 DNA binding sites and was inhibited by dominant negative E2F-1 or DP-1. Neu-induced transformation was inhibited by a cyclin D1 antisense or dominant negative E2F-1 construct in Rat-1 cells. Growth of NeuT-transformed mammary adenocarcinoma cells in nude mice was blocked by the cyclin D1 antisense construct. These results demonstrate that E2F-1 mediates a Neu-signaling cascade to cyclin D1 and identify cyclin D1 as a critical downstream target of neu-induced transformation.

Nociceptin receptor activation produces nitric oxide-mediated systemic hypotension

The purpose of the present study was to investigate the effects of L-N5-(1-iminoethyl)ornithine hydrochloride (L-NIO), an inhibitor of nitric oxide (NO) formation, and [Phe1-psi(CH2NH)-Gly2]Nociceptin(1-13)-NH2 (Phe-NOC), a nociceptin receptor antagonist, on the systemic vasodepressor response to nociceptin in the anesthetized rat. The systemic vasodepressor response to bolus intravenous (i.v.) injections of nociceptin was significantly reduced by L-NIO and Phe-NOC. The present data suggest activation of nociceptin receptors dilates the systemic vascular bed through a NO-dependent pathway. These data also demonstrate Phe-NOC is an efficacious and selective nociceptin receptor antagonist in vivo.