bluuebunny/crossref_metadata_2025 huggingface dataset:
New Insights into Biliverdin Reductase Functions: Linking Heme Metabolism to Cell Signaling
Authors: Maines Mahin D.
Published: November 2005

Biliverdin reductase (BVR) functions in cell signaling through three distinct tracks: a dual-specificity kinase that functions in the insulin receptor/MAPK pathways ( 25 , 29 , 51 ); a bzip-type transcription factor for ATF-2/CREB and HO-1 regulation ( 1 , 25 ); and a reductase that catalyzes the conversion of biliverdin to bilirubin ( 27 ). These, together with the protein’s primary and secondary features, intimately link BVR to the entire spectrum of cell-signaling cascades.
The KCNQ1 Potassium Channel: From Gene to Physiological Function
Authors: Jespersen Thomas , Grunnet Morten , Olesen Søren-Peter
Published: November 2005

The voltage-gated KCNQ1 (KvLQT1, Kv7.1) potassium channel plays a crucial role in shaping the cardiac action potential as well as in controlling the water and salt homeostasis in several epithelial tissues. KCNQ1 channels in these tissues are tightly regulated by auxiliary proteins and accessory factors, capable of modulating the properties of the channel complexes. This paper reviews the current knowledge about the KCNQ1 channel with a major focus on interacting proteins and physiological functions.
A Direct Test of Potential Roles for β3 and β5 Integrins in Growth and Metastasis of Murine Mammary Carcinomas
Authors: Taverna Daniela , Crowley Denise , Connolly Mary , Bronson Roderick T. , Hynes Richard O.
Published: November 2005

αvβ3 or αvβ5 integrins are widely expressed on blood and endothelial cells. Inhibition of the functions of these integrins has been reported to suppress neovascularization and tumor growth, suggesting that they may be critical modulators of angiogenesis. However, mice lacking these integrins exhibit extensive angiogenesis. Tumors arising from s.c. injections of tumor cells into mice lacking one or both integrins show enhanced tumor growth compared with growth in control mice due to both increased angiogenesis and to altered innate immune response. Other data suggest additional roles for these integrins, on either platelets or the tumor cells themselves, in enhancing tumor progression and metastasis. Here, we investigate the involvement of β3 and β5 integrins in the development and progression of mammary carcinomas. We intercrossed mouse mammary tumor virus (MMTV)-c-neu transgenic mice with β3 or β5 or β3β5 integrin-deficient mice and observed that multiple, large mammary tumors developed in 100% of mice on all genetic backgrounds. A statistically significant earlier onset of tumor growth was observed in the MMTV-c-neu/β3β5 integrin-null females compared with control mice. No major differences were observed in tumor size or number, vessel number or vessel structure and lung metastases were observed with similar frequency and size in all strains. MMTV-c-neu/β3β5 integrin-null mice had higher numbers of mammary acini, which may account for the earlier onset of tumors in this strain. These data indicate that αvβ3 or αvβ5 integrins are not essential for tumor growth and progression, although they might play some role in mammary gland development.
The Role of Peroxiredoxin II in Radiation-Resistant MCF-7 Breast Cancer Cells
Authors: Wang Tieli , Tamae Daniel , LeBon Thomas , Shively John E. , Yen Yun , Li Jian Jian
Published: November 2005

Although several signaling pathways have been suggested to be involved in the cellular response to ionizing radiation, the molecular basis of tumor resistance to radiation remains elusive. We have developed a unique model system based upon the MCF-7 human breast cancer cell line that became resistant to radiation treatment (MCF+FIR30) after exposure to chronic ionizing radiation. By proteomics analysis, we found that peroxiredoxin II (PrxII), a member of a family of peroxidases, is up-regulated in the radiation-derived MCF+FIR3 cells but not in the MCF+FIS4 cells that are relatively sensitive to radiation. Both MCF+FIR3 and MCF+FIS4 cell lines are from MCF+FIR30 populations. Furthermore, the resistance to ionizing radiation can be partially reversed by silencing the expression of PrxII by PrxII/small interfering RNA treatment of MCF+FIR3 resistant cells, suggesting that PrxII is not the sole factor responsible for the resistant phenotype. The relevance of this mechanism was further confirmed by the increased radioresistance in PrxII-overexpressing MCF+FIS4 cells when compared with vector control cells. The up-regulation of the PrxII protein in radioresistant cancer cells suggested that human peroxiredoxin plays an important role in eliminating the generation of reactive oxygen species by ionizing radiation. The present finding, together with the observation that PrxII is also up-regulated in response to ionizing radiation in other cell systems, strengthens the hypothesis that the PrxII antioxidant protein is involved in the cellular response to ionizing radiation and functions to reduce the intracellular reactive oxygen species levels, resulting in increased resistance of breast cancer cells to ionizing radiation.
Diminished Expression of Transcription Factors Nuclear Factor κB and CCAAT/Enhancer Binding Protein Underlies a Novel Tumor Evasion Mechanism Affecting Macrophages of Mammary Tumor–Bearing Mice
Authors: Torroella-Kouri Marta , Ma Xiaojing , Perry Giselle , Ivanova Milena , Cejas Pedro J. , Owen Jennifer L. , Iragavarapu-Charyulu Vijaya , Lopez Diana M.
Published: November 2005

Interactions between malignant tumors and the host immune system shape the course of cancer progression. The molecular basis of such interactions is the subject of immense interest. Proinflammatory cytokines produced by macrophages are critical mediators of immune responses that contribute to the control of the advancement of neoplasia. We have shown that the expressions of interleukin 12 (IL-12) and inducible nitric oxide synthase (iNOS) are decreased in macrophages from mammary tumor–bearing mice. In this study, we investigated the causes of IL-12 dysregulation and found deficient nuclear factor κB (NFκB) and CCAAT/enhancer binding protein (C/EBP) expression and function in tumor bearers' peritoneal macrophages. The constitutive expressions of NFκB p50, c-rel, p65, and C/EBPα and β, as well as the lipopolysaccharide-induced nuclear translocation and DNA binding of NFκB components and C/EBPα and β, are profoundly impaired in macrophages from mice bearing D1-DMBA-3 tumors. Because similar findings occur with the iNOS gene, it seems that it represents a novel mechanism by which tumor-derived factors interfere with the host immune defenses.
Novel Molecular Signaling and Classification of Human Clinically Nonfunctional Pituitary Adenomas Identified by Gene Expression Profiling and Proteomic Analyses
Authors: Moreno Carlos S. , Evans Chheng-Orn , Zhan Xianquan , Okor Mammerhi , Desiderio Dominic M. , Oyesiku Nelson M.
Published: November 2005

Pituitary adenomas comprise 10% of intracranial tumors and occur in about 20% of the population. They cause significant morbidity by compression of regional structures or the inappropriate expression of pituitary hormones. Their molecular pathogenesis is unclear, and the current classification of clinically nonfunctional tumors does not reflect any molecular distinctions between the subtypes. To further elucidate the molecular changes that contribute to the development of these tumors and reclassify them according to the molecular basis, we investigated 11 nonfunctional pituitary adenomas and eight normal pituitary glands, using 33 oligonucleotide GeneChip microarrays. We validated microarray results with the reverse transcription real-time quantitative PCR, using a larger number of nonfunctional adenomas. We also used proteomic analysis to examine protein expression in these nonfunctional adenomas. Microarray analysis identified significant increases in the expression of 115 genes and decreases in 169 genes, whereas proteomic analysis identified 21 up-regulated and 29 down-regulated proteins. We observed changes in expression of SFRP1, TLE2, PITX2, NOTCH3, and DLK1, suggesting that the developmental Wnt and Notch pathways are activated and important for the progression of nonfunctional pituitary adenomas. We further analyzed gene expression profiles of all nonfunctional pituitary subtypes to each other and identified genes that were affected uniquely in each subtype. These results show distinct gene and protein expression patterns in adenomas, provide new insight into the pathogenesis and molecular classification of nonfunctional pituitary adenomas, and suggest that therapeutic targeting of the Notch pathway could be effective for these tumors.
Steroid Receptor Regulation of Epidermal Growth Factor Signaling through Src in Breast and Prostate Cancer Cells: Steroid Antagonist Action
Authors: Migliaccio Antimo , Di Domenico Marina , Castoria Gabriella , Nanayakkara Merlin , Lombardi Maria , de Falco Antonietta , Bilancio Antonio , Varricchio Lilian , Ciociola Alessandra , Auricchio Ferdinando
Published: November 2005

Under conditions of short-term hormone deprivation, epidermal growth factor (EGF) induces DNA synthesis, cytoskeletal changes, and Src activation in MCF-7 and LNCaP cells. These effects are drastically inhibited by pure estradiol or androgen antagonists, implicating a role of the steroid receptors in these findings. Interestingly, EGF triggers rapid association of Src with androgen receptor (AR) and estradiol receptor α (ERα) in MCF-7 cells or ERβ in LNCaP cells. Here, we show that, through EGF receptor (EGFR) and erb-B2, EGF induces tyrosine phosphorylation of ER preassociated with AR, thereby triggering the assembly of ER/AR with Src and EGFR. Remarkably, experiments in Cos cells show that this complex stimulates EGF-triggered EGFR tyrosine phosphorylation. In turn, estradiol and androgen antagonists, through the Src-associated receptors, prevent Src activation by EGF and heavily reduce EGFR tyrosine phosphorylation and the subsequent multiple effects, including DNA synthesis and cytoskeletal changes in MCF-7 cells. In addition, knockdown of ERα or AR gene by small interfering RNA (siRNA) almost abolishes EGFR tyrosine phosphorylation and DNA synthesis in EGF-treated MCF-7 cells. The present findings reveal that steroid receptors have a key role in EGF signaling. EGFR tyrosine phosphorylation, depending on Src, is a part of this mechanism. Understanding of EGF-triggered growth and invasiveness of mammary and prostate cancer cells expressing steroid receptors is enhanced by this report, which reveals novel aspects of steroid receptor action.
Postreplicative Joining of DNA Double-Strand Breaks Causes Genomic Instability in DNA-PKcs–Deficient Mouse Embryonic Fibroblasts
Authors: Martín Marta , Genescà Anna , Latre Laura , Jaco Isabel , Taccioli Guillermo E. , Egozcue Josep , Blasco María A. , Iliakis George , Tusell Laura
Published: November 2005

Combined cytogenetic and biochemical approaches were used to investigate the contributions of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) in the maintenance of genomic stability in nonirradiated and irradiated primary mouse embryo fibroblasts (MEF). We show that telomere dysfunction contributes only marginally to genomic instability associated with DNA-PKcs deficiency in the absence of radiation. Following exposure to ionizing radiation, DNA-PKcs−/− MEFs are radiosensitized mainly as a result of the associated DNA double-strand break (DSB) repair defect. This defect manifests as an increase in the fraction of DSB rejoining with slow kinetics although nearly complete rejoining is achieved within 48 hours. Fifty-four hours after ionizing radiation, DNA-PKcs−/− cells present with a high number of simple and complex chromosome rearrangements as well as with unrepaired chromosome breaks. Overall, induction of chromosome aberrations is 6-fold higher in DNA-PKcs−/− MEFs than in their wild-type counterparts. Spectral karyotyping-fluorescence in situ hybridization technology distinguishes between rearrangements formed by prereplicative and postreplicative DSB rejoining and identifies sister chromatid fusion as a significant source of genomic instability and radiation sensitivity in DNA-PKcs−/− MEFs. Because DNA-PKcs−/− MEFs show a strong G1 checkpoint response after ionizing radiation, we propose that the delayed rejoining of DNA DSBs in DNA-PKcs−/− MEFs prolongs the mean life of broken chromosome ends and increases the probability of incorrect joining. The preponderance of sister chromatid fusion as a product of incorrect joining points to a possible defect in S-phase arrest and emphasizes proximity in these misrepair events.
Possible Detection of Pancreatic Cancer by Plasma Protein Profiling
Authors: Honda Kazufumi , Hayashida Yasuharu , Umaki Tomoko , Okusaka Takuji , Kosuge Tomoo , Kikuchi Satoru , Endo Mitsufumi , Tsuchida Akihiko , Aoki Tatsuya , Itoi Takao , Moriyasu Fuminori , Hirohashi Setsuo , Yamada Tesshi
Published: November 2005

The survival rate of pancreatic cancer patients is the lowest among those with common solid tumors, and early detection is one of the most feasible means of improving outcomes. We compared plasma proteomes between pancreatic cancer patients and sex- and age-matched healthy controls using surface-enhanced laser desorption/ionization coupled with hybrid quadrupole time-of-flight mass spectrometry. Proteomic spectra were generated from a total of 245 plasma samples obtained from two institutes. A discriminating proteomic pattern was extracted from a training cohort (71 pancreatic cancer patients and 71 healthy controls) using a support vector machine learning algorithm and was applied to two validation cohorts. We recognized a set of four mass peaks at 8,766, 17,272, 28,080, and 14,779 m/z, whose mean intensities differed significantly (Mann-Whitney U test, P < 0.01), as most accurately discriminating cancer patients from healthy controls in the training cohort [sensitivity of 97.2% (69 of 71), specificity of 94.4% (67 of 71), and area under the curve value of 0.978]. This set discriminated cancer patients in the first validation cohort with a sensitivity of 90.9% (30 of 33) and a specificity of 91.1% (41 of 45), and its discriminating capacity was further validated in an independent cohort at a second institution. When combined with CA19-9, 100% (29 of 29 patients) of pancreatic cancers, including early-stage (stages I and II) tumors, were detected. Although a multi-institutional large-scale study will be necessary to confirm clinical significance, the biomarker set identified in this study may be applicable to using plasma samples to diagnose pancreatic cancer.
Complement-Mediated Mechanisms in Anti-GD2 Monoclonal Antibody Therapy of Murine Metastatic Cancer
Authors: Imai Masaki , Landen Charles , Ohta Rieko , Cheung Nai-Kong V. , Tomlinson Stephen
Published: November 2005

The role of complement in antibody therapy of cancer is in general poorly understood. We used the EL4 syngeneic mouse model of metastatic lymphoma to investigate the role of complement in immunotherapy directed against GD2, a target of clinical relevance. IgG2a and IgM anti-GD2 therapy protected EL4-challenged mice from metastases and prolonged survival. Expression of CD59, an inhibitor of direct complement-mediated cytotoxicity (CMC), effectively protected EL4 cells from CMC in vitro but did not affect the outcome of monoclonal antibody therapy. Protection by IgG therapy was also unaffected in mice deficient in C3 or complement receptor 3 (CR3) but was almost completely abrogated in FcγR I/III–deficient mice. These data indicate a crucial role for antibody-dependent cell-mediated cytoxicity (ADCC). However, at lower doses of IgG, therapeutic effect was partially abrogated in C3-deficient mice, indicating complement-mediated enhancement of ADCC at limiting IgG concentration. In contrast to IgG, the therapeutic effect of IgM was completely abrogated in C3-deficient mice. High level expression of CD59 on EL4 did not influence IgM therapy, suggesting IgM functions by complement-dependent cell-mediated cytotoxicity (CDCC), a mechanism thought to be inactive against tumor cells. Thus, IgG and IgM can operate via different primary mechanisms of action, and CDCC and complement-dependent enhancement of ADCC mechanisms are operative in vivo. The effects of complement can be supplemental to other antibody-mediated mechanisms and likely have increased significance at limiting antibody concentration or low antigen density.
Loss of the hSNF5 Gene Concomitantly Inactivates p21CIP/WAF1 and p16INK4a Activity Associated with Replicative Senescence in A204 Rhabdoid Tumor Cells
Authors: Chai Jingjing , Charboneau Aubri L. , Betz Bryan L. , Weissman Bernard E.
Published: November 2005

hSNF5, the smallest member of the SWI/SNF chromatin remodeling complex, is lost in most malignant rhabdoid tumors (MRT). In MRT cell lines, reexpression of hSNF5 induces G1 cell cycle arrest, elevated p16INK4a, and activated replicative senescence markers, such as β-galactosidase (β-Gal) and plasminogen activator inhibitor-1. To compare the replicative senescence caused by hSNF5 in A204 cells to normal cellular senescence, we examined the activation of both p16INK4a and p21CIP/WAF1. Analogous to normal cellular senescence, both p16INK4a and p21CIP/WAF1 were up-regulated following hSNF5 restoration. Furthermore, we found that hSNF5 bound the p16INK4a and p21CIP/WAF1 promoters, suggesting that it directly regulates transcription of these genes. Using p16INK4a RNA interference, we showed its requirement for the replicative senescence caused by hSNF5 but not the growth arrest. Instead, p21CIP/WAF1 remained activated by hSNF5 in the absence of high p16INK4a expression, apparently causing the growth arrest in A204. Interestingly, we also found that, in the absence of p16INK4a, reexpression of hSNF5 also increased protein levels of a second cyclin-dependent kinase (CDK) inhibitor, p18INK4c. However, our data show that lack of hSNF5 does not abrogate cellular responsiveness to DNA damage or growth-inhibitory factors. In summary, our studies suggest that hSNF5 loss may influence the regulation of multiple CDK inhibitors involved in replicative senescence.
Activation of Glycogen Synthase Kinase 3β Disrupts the Binding of Hexokinase II to Mitochondria by Phosphorylating Voltage-Dependent Anion Channel and Potentiates Chemotherapy-Induced Cytotoxicity
Authors: Pastorino John G. , Hoek Jan B. , Shulga Nataly
Published: November 2005

Transformed cells are highly glycolytic and overexpress hexokinase II (HXK II). HXK II is capable of binding to the mitochondria through an interaction with the voltage-dependent anion channel (VDAC), an abundant outer mitochondrial membrane protein. The binding of HXK II to mitochondria has been shown to protect against loss of cell viability. Akt activation inhibits apoptosis partly by promoting the binding of HXK II to the mitochondria, but the mechanism through which Akt accomplishes this has not been characterized. The present report shows that Akt mediates the binding of HXK II to the mitochondria by negatively regulating the activity of glycogen synthase kinase 3β (GSK3β). On inhibition of Akt, GSK3β is activated and phosphorylates VDAC. HXK II is unable to bind VDAC phosphorylated by GSK3β and dissociates from the mitochondria. Inhibition of Akt potentiates chemotherapy-induced cytotoxicity, an effect that is dependent on GSK3β activation and its attendant ability to disrupt the binding of HXK II to the mitochondria. Moreover, agents that can force the detachment of HXK II from mitochondria in the absence of Akt inhibition or GSK3β activation promoted a synergistic increase in cell killing when used in conjunction with chemotherapeutic drugs. Such findings indicate that interference with the binding of HXK II to mitochondria may be a practicable modality by which to potentiate the efficacy of conventional chemotherapeutic agents.
Some Oral Poliovirus Vaccines Were Contaminated with Infectious SV40 after 1961
Authors: Cutrone Rochelle , Lednicky John , Dunn Glynis , Rizzo Paola , Bocchetta Maurizio , Chumakov Konstantin , Minor Philip , Carbone Michele
Published: November 2005

Some polio vaccines prepared from 1954 to 1961 were contaminated with infectious SV40. It has been assumed that all polio vaccines were SV40 free in the United States after 1961 and in other countries after 1962. Following a WHO requirement that was prompted by the detection of SV40 in some human tumors, we conducted a multilaboratory study to test for SV40 polio vaccines prepared after 1961. Vaccine samples from 13 countries and the WHO seed were initially tested by PCR. The possible presence of intact and/or infectious SV40 DNA in PCR-positive samples was tested by transfection and infection of permissive CV-1 cells. All results were verified by immunohistochemistry, cloning, and sequencing. All the vaccines were SV40 free, except for vaccines from a major eastern European manufacturer that contained infectious SV40. We determined that the procedure used by this manufacturer to inactivate SV40 in oral poliovirus vaccine seed stocks based on heat inactivation in the presence of MgCl2 did not completely inactivate SV40. These SV40-contaminated vaccines were produced from early 1960s to about 1978 and were used throughout the world. Our findings underscore the potential risks of using primary monkey cells for preparing poliovirus vaccines, because of the possible contamination with SV40 or other monkey viruses, and emphasize the importance of using well-characterized cell substrates that are free from adventitious agents. Moreover, our results indicate possible geographic differences in SV40 exposure and offer a possible explanation for the different percentage of SV40-positive tumors detected in some laboratories.
The Differential Effects of Mutant p53 Alleles on Advanced Murine Lung Cancer
Authors: Jackson Erica L. , Olive Kenneth P. , Tuveson David A. , Bronson Roderick , Crowley Denise , Brown Michael , Jacks Tyler
Published: November 2005

We report a direct comparison of the differential effects of individual p53 mutations on lung tumor growth and progression, and the creation of a murine model of spontaneous advanced lung adenocarcinoma that closely recapitulates several aspects of advanced human pulmonary adenocarcinoma. We generated compound conditional knock-in mice with mutations in K-ras combined with one of three p53 alleles: a contact mutant, a structural mutant, or a null allele. p53 loss strongly promoted the progression of K-ras–induced lung adenocarcinomas, yielding a mouse model that is strikingly reminiscent of advanced human lung adenocarcinoma. The influence of p53 loss on malignant progression was observed as early as 6 weeks after tumor initiation. Furthermore, we found that the contact mutant p53R270H, but not the structural mutant p53R172H, acted in a partially dominant-negative fashion to promote K-ras–initiated lung adenocarcinomas. However, for both mutants, loss-of-heterozygosity occurred uniformly in advanced tumors, highlighting a residual tumor-suppressive function conferred by the remaining wild-type allele of p53. Finally, a subset of mice also developed sinonasal adenocarcinomas. In contrast to the lung tumors, expression of the point-mutant p53 alleles strongly promoted the development of sinonasal adenocarcinomas compared with simple loss-of-function, suggesting a tissue-specific gain-of-function.
Epigenetic Transdifferentiation of Normal Melanocytes by a Metastatic Melanoma Microenvironment
Authors: Seftor Elisabeth A. , Brown Kevin M. , Chin Lynda , Kirschmann Dawn A. , Wheaton William W. , Protopopov Alexei , Feng Bin , Balagurunathan Yoganand , Trent Jeffrey M. , Nickoloff Brian J. , Seftor Richard E.B. , Hendrix Mary J.C.
Published: November 2005

The clinical management of cutaneous melanoma would benefit significantly from a better understanding of the molecular changes that occur during melanocytic progression to a melanoma phenotype. To gain unique insights into this process, we developed a three-dimensional in vitro model that allows observations of normal human melanocytes interacting with a metastatic melanoma matrix to determine whether these normal cells could be reprogrammed by inductive cues in the tumor cell microenvironment. The results show the epigenetic transdifferentiation of the normal melanocytic phenotype to that of an aggressive melanoma-like cell with commensurate increased migratory and invasive ability with no detectable genomic alterations. Removal of the transdifferentiated melanocytes from the inductive metastatic melanoma microenvironment results in a reversion to their normal phenotype. However, a normal melanocyte microenvironment had no epigenetic influence on the phenotype of metastatic melanoma cells. This novel approach identifies specific genes involved in the transdifferentiation of melanocytes to a more aggressive phenotype, which may offer significant therapeutic value.
Mechanisms of Inactivation of the Receptor Tyrosine Kinase EPHB2 in Colorectal Tumors
Authors: Alazzouzi Hafid , Davalos Veronica , Kokko Antti , Domingo Enric , Woerner Stefan M. , Wilson Andrew J. , Konrad Lars , Laiho Päivi , Espín Eloi , Armengol Manel , Imai Kohzoh , Yamamoto Hiroyuki , Mariadason John M. , Gebert Johannes F. , Aaltonen Lauri A. , Schwartz Simo , Arango Diego
Published: November 2005

The receptor tyrosine kinase EPHB2 has recently been shown to be a direct transcriptional target of TCF/β-catenin. Premalignant lesions of the colon express high levels of EPHB2 but the expression of this kinase is reduced or lost in most colorectal carcinomas. In addition, inactivation of EPHB2 has been shown to accelerate tumorigenesis initiated by APC mutation in the colon and rectum. In this study, we investigated the molecular mechanisms responsible for the inactivation of EPHB2 in colorectal tumors. We show here the presence of mutations in repetitive sequences in exon 17 of EPHB2 in 6 of 29 adenomas with microsatellite instability (MSI), and 101 of 246 MSI carcinomas (21% and 41%, respectively). Moreover, we found EPHB2 promoter hypermethylation in 54 of the 101 colorectal tumors studied (53%). Importantly, EPHB2 expression was restored after treatment of EPHB2-methylated colon cancer cells with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine. In conclusion, in this study, we elucidate the molecular mechanisms of inactivation of EPHB2 and show for the first time the high incidence of frameshift mutations in MSI colorectal tumors and aberrant methylation of the regulatory sequences of this important tumor suppressor gene.
Induction of Renal Tumorigenesis with Elevated Levels of Somatic Loss of Heterozygosity in Tsc1+/- Mice on a Blm-Deficient Background
Authors: Wilson Catherine , Idziaszczyk Shelley , Colley James , Humphreys Vikki , Guy Carol , Maynard Julie , Sampson Julian R. , Cheadle Jeremy P.
Published: November 2005

A Bloom's deficient mouse model (Blmm3/m3) has been shown to induce colorectal tumorigenesis when crossed with Apc+/Min mice. Here, we investigated whether the Blmm3/m3 genotype could induce tumorigenesis in extracolonic tissues in tuberous sclerosis 1–deficient (Tsc1+/−) mice that are predisposed to renal cystadenomas and carcinomas. Genotyping of offspring from Tsc1+/− Blm+/m3 intercrosses showed that a ∼24% excess of Tsc1+/− over Tsc1+/+ mice died before weaning (P = 0.016), although Blm deficiency had no cumulative effect on Tsc1+/− survival. Tsc1+/− Blmm3/m3 mice had significantly more macroscopic and microscopic renal lesions at 3 to 6 months compared with Tsc1+/− Blm+/m3 mice (P =0.0003 and 0.0203, respectively), and their tumors showed significantly increased levels of somatic loss of heterozygosity (LOH) of the wild-type Tsc1 (Tsc1wt) allele compared with those from Tsc1+/− Blm+/+ mice (P < 0.0001). Tsc1+/− Blm+/m3 mice did not show significantly more renal lesions compared with Tsc1+/− Blm+/+ animals; however, their lesions still showed significantly increased levels of somatic LOH of the Tsc1wt allele (P = 0.03). Ninety-five percent (19 of 20) of lesions from Tsc1+/− Blm+/m3 mice retained the wild-type Blm (Blmwt) allele, indicating that the increased somatic LOH at Tsc1 was mediated by Blm haploinsufficiency. Renal lesions from a Blm-deficient background stained positively with anti-phospho-S6 ribosomal protein (Ser240/244), suggesting that these lesions develop through the normal pathway of Tsc-associated tumorigenesis. This work shows the use of the Blmm3/m3 mice for inducing renal tumorigenesis, and the high levels (∼87%) of LOH in the resultant tumors will help facilitate mapping of loci involved in tumor progression.
The Basis of Gender Assignment in Disorders of Somatosexual Differentiation
Authors: Hiort Olaf , Thyen Ute , Holterhus Paul-Martin
Published: November 2005

Sex assignment of patients with disorders of somatosexual differentiation is a controversial topic. The aim is to enable the patient to develop a stable gender identity during childhood, adolescence and adulthood. Enormous advances have recently been made in our knowledge of the molecular mechanisms of sexual differentiation and it is understood that long-term outcome may depend on the underlying diagnosis. There is increasing evidence that genital development is dependent on the action of androgenic steroids; moreover, both androgens and oestrogens may have an impact on other developing organs including neuronal structures such as the brain. Long-term outcome studies on the various intersexuality disorders are desperately needed in order to establish a basis for evidence-based medicine regarding sex assignment and treatment options. Premature decisions leading to irreversible interventions before an accurate diagnosis has been established must be avoided.
Hormone Treatment of the Adult Transsexual Patient
Authors: Gooren Louis
Published: November 2005

Hormonal reassignment has two aims: (1) to reduce the hormonally induced secondary sex characteristics of the original sex and (2) to induce the secondary sex characteristics of the new sex. In Europe, cyproterone acetate is generally used to inhibit androgens in male-to-female transsexuals. Medroxyprogesterone acetate is an acceptable, though less effective, alternative. To induce feminization there is a wide range of oestrogens. Oral ethinyloestradiol is a potent and inexpensive oestrogen, but it may cause venous thrombosis. Oral 17β-oestradiol valerate or transdermal 17β-oestradiol is the treatment of choice. The goal of treatment in female-to-male transsexuals is to induce virilization, including a male pattern of sexual hair, a male voice and male physical contours, and to stop menses. The principal hormonal treatment is a testosterone preparation. Hormone-dependent tumours have been encountered and surveillance is necessary.
Isolated Gonadotropic Deficiency with and without Anosmia: A Developmental Defect or a Neuroendocrine Regulation Abnormality of the Gonadotropic Axis
Authors: de Roux Nicolas
Published: November 2005

Hypogonadotropic hypogonadism has been described in several human genetic diseases. Congenital isolated hypogonadotropic hypogonadism is classified into two categories: one that is associated with anosmia (Kallmann syndrome) and one that is apparently isolated. Mutations and deletions of the KAL1 gene, which encodes for a protein involved in cell adhesion, have been observed in many cases of the X-linked form of Kallmann syndrome. Recently, loss-of-function mutations of fibroblast growth factor receptor-1 (FGFR1) were associated with an autosomal dominant form of Kallmann syndrome. Genotype-phenotype correlations confirm the large spectrum of the phenotype due to FGFR1 mutations. Cases of isolated hypogonadotropic hypogonadism were considered to be idiopathic until the description of mutations of the gonadotropin releasing hormone receptor, luteinizing hormone and follicle stimulating hormone genes. However, defects in these genes only account for a small percentage of familial cases, which suggests that other proteins may be involved in regulation of the gonadotropic axis. We recently described GPR54 as one of these proteins by genome mapping in a very informative family. In vivo studies and genotype-phenotype correlations indicate that gonadotropic axis regulation by GPR54 occurs mainly at the level of the hypothalamus.
Turner Syndrome in Adulthood
Authors: Gravholt Claus Højbjerg
Published: November 2005

Turner syndrome is a common genetic disorder associated with abnormalities of the X chromosome and occurs in about 50 per 100,000 liveborn girls. It is associated with reduced adult height, gonadal dysgenesis and thus insufficient circulating levels of female sex steroids and infertility. Morbidity and mortality are increased throughout the lifespan. The average intellectual performance is within the normal range. A number of recent clinical studies have given new insight particularly into the adult phase of Turner syndrome. Treatment with growth hormone during childhood and adolescence enables a considerable gain in adult height. In most cases puberty has to be induced and female sex hormone replacement therapy is given during adulthood. Type 2 diabetes is often seen, and hypertension and associated cardiovascular disorders are frequent. The proper treatments of these disorders have not been firmly established. Since the risk of cardiovascular and endocrinological disease is clearly elevated, proper care during adulthood is crucial. Cognition and social functioning are altered in Turner syndrome.
Hormonal Regulation of Growth Plate Cartilage
Authors: Sävendahl Lars
Published: November 2005

Longitudinal bone growth occurs in the growth plate through a process called endochondral bone formation, a process where resting zone chondrocytes are recruited to start active proliferation and then undergo differentiation, followed by apoptosis and later mineralization. The balance between proliferation and differentiation is a crucial regulatory step controlled by various growth factors/hormones acting in both endocrine and paracrine/autocrine ways. From studies of individuals with aromatase deficiency and a boy with defective oestrogen receptor (ER)-alpha it has become clear that oestrogen action is indispensable for normal pubertal growth and growth plate fusion. Both oestrogen receptors, ER-alpha and ER-beta, are expressed in the growth plate in boys and girls throughout pubertal development. Any functional role of ER-beta has not yet been defined in the human growth plate. Increased understanding about the effects of oestrogen and the interactions between oestrogens and other endocrine factors within the growth plate is important for the development of new treatment strategies in different disorders affecting longitudinal bone growth. As new specific modulators of oestrogen receptors are developed, these could offer more specific ways to modulate longitudinal growth and growth plate fusion.
Autofluorescence and Angiographic Findings of Retinal Astrocytic Hamartomas in Tuberous Sclerosis
Authors: Mennel Stefan , Meyer Carsten H. , Eggarter Fred , Peter Silvia
Published: November 2005

Objective: To describe fundus autofluorescence (AF), fluorescein angiography (FA) and indocyanine green angiography (ICGA) in different types of retinal astrocytic hamartomas in tuberous sclerosis (Morbus Bourneville-Pringle). Methods: Two eyes with 8 lesions, i.e. type 1 (n = 7) and type 3 (n = 1), were examined. AF pictures were taken prior to injection, FA and ICGA images were obtained in the early and the late phase. To achieve additional cases, a systematic literature review with exten- sive Internet and library search was performed. Results:  Strong AF was seen in type 2 and type 3 retinal astrocytic hamartomas, whereas type 1 lesions blocked the physiologic fundus AF. Fluorescence angiography of all types of lesions revealed hypofluorescence in early frames and hyperfluorescence originating from leakage in late frames. ICGA showed a subtle blockade in type 1, a total blockade in type 2 and in the central part and a partial blockade in the peripheral part in type 3 lesions. Conclusions: Retinal astrocytic hamartomas in tuberous sclerosis can be easily detected by angiography, especially type 1 lesions which are difficult to visualize by funduscopy. Early- and late-phase fluorescein angiography and ICGA are helpful to differentiate the three lesion types.
Detection of Early Diabetic Change with Optical Coherence Tomography in Type 2 Diabetes Mellitus Patients without Retinopathy
Authors: Sugimoto Masahiko , Sasoh Mikio , Ido Masashi , Wakitani Yoshikatsu , Takahashi Chisato , Uji Yukitaka
Published: November 2005

Purpose: To detect early diabetic damage in type 2 diabetes mellitus patients with no diabetic retinopathy (NDR) using optical coherence tomography (OCT) and to evaluate OCT as a clinical test. Methods: Thirty-two patients with NDR (n = 32) were enrolled. We examined retinal and retinal nerve fiber layer (RNFL) thickness using OCT. Two healthy normal populations were also enrolled for the retinal thickness (n = 48) and RNFL thickness (n = 34). Both OCT measurements were obtained in four areas (temporal, superior, nasal and inferior). The receiver operator characteristic (ROC) curve was generated to evaluate the predictor variables. Results: Comparing the normal and NDR eyes, retinal thickness significantly increased (p = 0.03) and RNFL thickness significantly decreased (p = 0.02) in the superior areas. The area under the ROC curve was 0.65 for the superior retinal thickness and 0.63 for the superior RNFL thickness. Conclusions: Both OCT measurements can detect early retinal damage in NDR patients.
Gender-Related Differences in the Physiology of the Stratum Corneum
Authors: Jacobi Ute , Gautier Julien , Sterry Wolfram , Lademann Jürgen
Published: November 2005

Background: Only few studies on gender-related differences in skin physiology have been performed – and they provided conflicting results. Objective: In the present study, the effect of gender on the physiology of the stratum corneum was studied. Methods: The physiological parameters transepidermal water loss, pH value, hydration and sebum content were determined on the flexor forearms of 6 female and 6 male volunteers. In addition, stratum corneum samples, removed by tape stripping, were studied for amount, spectroscopic properties, protein content, and mass. Results: The skin of women was characterized by a significantly higher pH value (5.6 ± 0.4) than that of men (4.3 ± 0.4, p < 0.05). Protein absorption was the only other parameter significantly dependent on gender (p < 0.05). Both effects might be caused by differences in human biology, such as hormonal status. Conclusion: Therefore, the gender of the volunteers should be considered in dermatologic studies.
Skin Manifestations of West Nile Virus Infection
Authors: Del Giudice P. , Schuffenecker I. , Zeller H. , Grelier M. , Vandenbos F. , Dellamonica P. , Counillon E.
Published: November 2005

West Nile virus (WNV) infection is a potentially lethal arbovirus infection. Many notable outbreaks have occurred during the last few years throughout the world, including Europe and the USA. The severity of the disease is mainly related to the neurological complications. A maculopapular exanthema is reported as a clinical sign of the disease. Recently an outbreak of WNV infection occurred in southern France. Three patients out of 6 had a similar skin roseola-like eruption. The cluster of 3 cases of similar febrile roseola of unexplained cause during the same week led to the diagnosis of the first WNV human outbreak in France for 40 years.
Comparative Clinicopathological Manifestations of Human Aspergillosis
Authors: Piérard Gérald E. , Arrese Jorge E. , Quatresooz Pascale
Published: November 2005

Aspergillus species are important fungi of the environment, some of them being responsible for severe infections. Many distinct diseases form the human aspergillosis spectrum. The pathomechanisms differ according to the affected organ and the immune status of the patient. The fungus can be responsible for allergic reactions. It may also act as a saprophytic colonizer of air spaces. Infection may remain limited to the skin and nails. It may also be invasive, particularly in immunocompromised patients, in the lungs, paranasal sinus and gastrointestinal tract. Hematogeneous disseminated aspergillosis represents another dramatic form of the disease.
Effect of Trimethoprim-Sulfamethoxazole on Na+ and K+ Transport Properties in the Rabbit Cortical Collecting Duct Perfused in vitro
Authors: Muto Shigeaki , Tsuruoka Shuichi , Miyata Yukio , Fujimura Akio , Kusano Eiji
Published: November 2005

Background: In this study, the membrane mechanisms of hyperkalemia caused by trimethoprim-sulfamethoxazole (TMP-SMX) combination antibiotics were assessed in the cortical collecting duct (CCD). Methods: We used the microelectrode technique and flux measurements, and examined the effects of TMP and SMX on electrical properties of the apical and basolateral membranes in the rabbit CCD perfused in vitro. Results: TMP in the lumen caused increases in apical membrane voltage, fractional apical membrane resistance (fRA), and transepithelial resistance (RT), all effects which were completely inhibited by luminal amiloride, but not by luminal Ba2+. The luminal TMP inhibited both net Na+ reabsorption and K+ secretion in the CCD. TMP in the bath slightly but significantly depolarized transepithelial voltage and basolateral membrane voltage without influencing fRA or RT. SMX in the lumen or bath had no effect on barrier voltages or resistances. Conclusion: TMP mainly acts on the apical membrane of the CCD, inhibits the amiloride-sensitive macroscopic Na+ conductance in this membrane, and thereby decreases the net driving force for K+ exit across the membrane, resulting in an inhibition of K+ secretion. SMX in the lumen or bath had no effect on the CCD.
Organ-Specific Collagen Expression: Implications for Renal Disease
Authors: Alexakis Catherine , Maxwell Patrick , Bou-Gharios George
Published: November 2005

Chronic kidney disease is characterized by progressive accumulation of extracellular matrix and scarring, leading to the loss of kidney function. Excess deposition of the collagen family of proteins is the hallmark of kidney fibrosis. In this review, we survey the collagens that are associated with renal disease and we highlight the use of a transgenic approach to identify cis-acting sequences in the collagen type I promoter which are capable of directing collagen type I expression specifically in the kidney. Ultimately it may be possible to use this approach to halt the accumulation of collagen selectively in this organ.
Use of Proton Pump Inhibitors: An Exploration of the Attitudes, Knowledge and Perceptions of General Practitioners
Authors: Raghunath A.S. , Hungin A.P.S. , Cornford C.S. , Featherstone V.
Published: November 2005

Background/Aim: Proton pump inhibitor (PPI) prescribing is costly. The volume of PPI prescription is also increasing, despite little evidence that would justify the increase. General practitioners (GPs) are largely responsible for PPI prescribing, yet knowledge of their views concerning PPIs which might explain the apparent anomaly of prescribing costly drugs without justification is lacking. The aim of this study is therefore to investigate how GPs make decisions about PPI prescribing. Method: Qualitative study design using focus groups of 34 GPs and 15 training GPs analysed according to grounded theory principles and use of constant comparative analysis. Results:The participants showed agreement about the clinical factors potentially relevant to PPI prescribing such as age of presentation and endoscopy, issues of Helicobacter pylori eradication and issues around malignancy. There was considerable controversy, however, as to how to apply those factors in real clinical consultations. GPs in training and academic GPs tended to be more conservative; service-based GPs more pragmatic. There was agreement about the need to review long-term PPI medication, but controversy about whether the conventional ‘step-up step-down’ approach was realistic in practice. Good agreement was apparent about the effectiveness, the cost implications, and some of the ethical issues surrounding PPIs, but considerable controversy as to how far such factors should influence prescribing of PPIs. Conclusion:The GPs showed good understanding and knowledge of the issues surrounding PPI prescribing. There was considerable controversy as to how such knowledge should be translated into practice.
Adenosine-Stimulated Atrial Natriuretic Peptide Release Through A1Receptor Subtype
Authors: Yuan Kuichang , Cao Chunhua , Han Jeong Hee , Kim Sung Zoo , Kim Suhn Hee
Published: November 2005

Adenosine acts as an important protector of ischemic myocardium through coronary vasodilation and the depression of cardiac contractility. The protective effect of adenosine may partly relate to the cardiac hormone atrial natriuretic peptide (ANP). The aim of the present study was to investigate the effects of adenosine and the adenosine receptor subtype on atrial hemodynamics and ANP release using isolated perfused beating rat atria. Adenosine, a nonselective adenosine receptor agonist, increased the ANP release with negative inotropism in a dose-dependent manner. Adenosine-stimulated ANP release was attenuated by a selective A1antagonist but not A2Aantagonist or A3antagonist. The order of potency of the various agonists for the ANP release was A1agonists≫A3agonist= adenosine>A2Aagonist. The order of potency for the negative inotropy was A1agonists>adenosine=A2Aagonist>A3agonist. The negative inotropism and ANP release by a specific A1agonist (N6-cyclopentyl-adenosine) were also attenuated by A1antagonist but not A2Aantagonist or A3antagonist. Treatment with A1agonist resulted in a decrease of cAMP contents in atria and perfusates. The agonist-stimulated ANP release was significantly attenuated in the presence of forskolin, isoproterenol 8-Br-cAMP, or an adenylyl cyclase inhibitor. These results suggest that the A1receptor subtype is responsible for the adenosine-induced ANP release and negative inotropism through adenylyl cyclase–cAMP pathway.
Body Mass Index and Angiotensin-Dependent Control of the Renal Circulation in Healthy Humans
Authors: Ahmed Sofia B. , Fisher Naomi D.L. , Stevanovic Radomir , Hollenberg Norman K.
Published: November 2005

Obesity is increasingly recognized as a risk factor for renal disease, but the mechanism is unclear. Renal plasma flow response to captopril, as an index of renin-angiotensin system activity, was measured by para-aminohippurate clearance technique in 100 healthy, normotensive subjects in balance on a high-salt diet. Of the 100 subjects, body mass index exceeded 25 in 56 and exceeded 30 in 22. The average vasodilator response to captopril was 27±7 mL/min per 1.73 m
2
(
P
<0.0001). After adjustment for other predictors of the renal plasma flow response to captopril using a multivariate linear regression model, there was a highly significant relationship between age- and plasma renin activity–adjusted body mass index and the renal plasma flow response to captopril; however, a quadratic model provided a substantially better fit (
r
=0.55;
P
<0.0001;
P
=0.03 versus linear correlation). The strong association between increasing body mass index and angiotensin-dependent control of the renal circulation suggests that this may be a mechanism by which obesity contributes to renal disease. Weight loss should be considered in the overweight or obese patient for renal protection.