A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

Targeted selection of HIV-specific antibody mutations by engineering B cell maturation

INTRODUCTION

A major goal of HIV-1 vaccine development is the design of immunogens that induce broadly neutralizing antibodies (bnAbs). However, vaccination of humans has not resulted in the induction of affinity-matured and potent HIV-1 bnAbs. To devise effective vaccine strategies, we previously determined the maturation pathway of select HIV-1 bnAbs from acute infection through neutralizing antibody development. During their evolution, bnAbs acquire an abundance of improbable amino acid substitutions as a result of nucleotide mutations at variable region sequences rarely targeted by activation-induced cytidine deaminase, the enzyme responsible for antibody mutation. A subset of improbable mutations is essential for broad neutralization activity, and their acquisition represents a key roadblock to bnAb development.

RATIONALE

Current bnAb lineage-based vaccine strategies can initiate bnAb lineage development in animal models but have not specifically elicited the improbable mutations required for neutralization breadth. Induction of bnAbs requires vaccine strategies that specifically engage bnAb precursors and subsequently select for improbable mutations required for broadly neutralizing activity. We hypothesized that vaccination with immunogens that bind with moderate to high affinity to bnAb B cell precursors, and with higher affinity to precursors that have acquired improbable mutations, could initiate bnAb B cell lineages and select for key improbable mutations required for bnAb development.

RESULTS

We elicited serum neutralizing HIV-1 antibodies in human bnAb precursor knock-in mice and wild-type macaques vaccinated with immunogens designed to select for improbable mutations. We designed two HIV-1 envelope immunogens that bound precursor B cells of either a CD4 binding site or V3-glycan bnAb lineage. In vitro, these immunogens bound more strongly to bnAb precursors once the precursor acquired the desired improbable mutations. Vaccination of macaques with the CD4 binding site–targeting immunogen induced CD4 binding site serum neutralizing antibodies. Antibody sequences elicited in human bnAb precursor knock-in mice encoded functional improbable mutations critical for bnAb development. In bnAb precursor knock-in mice, we isolated a vaccine-elicited monoclonal antibody bearing functional improbable mutations that was capable of neutralizing multiple HIV-1 global isolates. Structures of a bnAb precursor, a bnAb, and the vaccine-elicited antibody revealed the precise roles that acquired improbable mutations played in recognizing the HIV-1 envelope. Thus, our immunogens elicited antibody responses in macaques and knock-in mice that exhibited the mutational patterns, structural characteristics, or neutralization profiles of nascent broadly neutralizing antibodies.

CONCLUSION

Our study represents a proof of concept for targeted selection of improbable mutations to guide antibody affinity maturation. Moreover, this study demonstrates a rational strategy for sequential immunogen design to circumvent the difficult roadblocks in HIV-1 bnAb induction by vaccination. We show that immunogens should exhibit differences in affinity across antibody maturation stages where improbable mutations are necessary for the desired antibody function. This strategy of selection of specific antibody nucleotides by immunogen design can be applied to B cell lineages targeting other pathogens where guided affinity maturation is needed for a protective antibody response.

A mixed-methods study to explore the supportive care needs of breast cancer survivors

OBJECTIVE

Needs assessment is the essence of quality cancer survivorship care. The aim of this study was to explore the supportive care needs of breast cancer survivors (BCS) in the first 5 years post treatment.

METHODS

A mixed-methods approach was employed. A quantitative study included a Supportive Care Needs Survey, which was completed by 250 BCS to identify the level of their needs for help. The quantitative data informed semistructured qualitative interviews undertaken with 60 BCS to explore in detail their posttreatment needs and experiences.

RESULTS

32.4% and 16.8% reported 1 to 5 and greater than or equal to 6 needs for help, respectively. The regression analyses revealed that women within 2 years posttreatment and with higher educational level had higher levels of Psychological and Health Care System/Information needs. The qualitative data revealed "continuity of care" and "lifestyle advice and self-management" as prominent survivorship concerns. It was shown that determination to continue normal life, social support, and feeling overwhelmed by information were all experienced as important influences on survivors' need for help.

CONCLUSIONS

Posttreatment needs vary with BCS characteristics and to the domains concerned. The approach to posttreatment care needs to be personalized and viable.

Induction of HIV Neutralizing Antibody Lineages in Mice with Diverse Precursor Repertoires

The design of immunogens that elicit broadly reactive neutralizing antibodies (bnAbs) has been a major obstacle to HIV-1 vaccine development. One approach to assess potential immunogens is to use mice expressing precursors of human bnAbs as vaccination models. The bnAbs of the VRC01-class derive from the IGHV1-2 immunoglobulin heavy chain and neutralize a wide spectrum of HIV-1 strains via targeting the CD4 binding site of the envelope glycoprotein gp120. We now describe a mouse vaccination model that allows a germline human IGHV1-2(∗)02 segment to undergo normal V(D)J recombination and, thereby, leads to the generation of peripheral B cells that express a highly diverse repertoire of VRC01-related receptors. When sequentially immunized with modified gp120 glycoproteins designed to engage VRC01 germline and intermediate antibodies, IGHV1-2(∗)02-rearranging mice, which also express a VRC01-antibody precursor light chain, can support the affinity maturation of VRC01 precursor antibodies into HIV-neutralizing antibody lineages.

SIRT7 represses Myc activity to suppress ER stress and prevent fatty liver disease

Nonalcoholic fatty liver disease is the most common chronic liver disorder in developed countries. Its pathogenesis is poorly understood, and therapeutic options are limited. Here, we show that SIRT7, an NAD(+)-dependent H3K18Ac deacetylase, functions at chromatin to suppress ER stress and prevent the development of fatty liver disease. SIRT7 is induced upon ER stress and is stabilized at the promoters of ribosomal proteins through its interaction with the transcription factor Myc to silence gene expression and to relieve ER stress. SIRT7-deficient mice develop chronic hepatosteatosis resembling human fatty liver disease. Myc inactivation or pharmacological suppression of ER stress alleviates fatty liver caused by SIRT7 deficiency. Importantly, SIRT7 suppresses ER stress and reverts the fatty liver disease in diet-induced obese mice. Our study identifies SIRT7 as a cofactor of Myc for transcriptional repression and delineates a druggable regulatory branch of the ER stress response that prevents and reverts fatty liver disease.

Higher protein diet for weight management in young overweight women: a 12-month randomized controlled trial

Clinical research on weight management in young women is limited. This randomized controlled trial compared the efficacy of two iso-energetically restricted (5600 kJ) diets [higher protein (HP): 32% protein, 41% carbohydrate, 25% fat or higher carbohydrate (HC): 20, 58, 21%, respectively] in 71 (HP: n = 36; HC: n = 35) young healthy women (18-25 years; body mass index ≥ 27.5 kg/m2) for weight (kg; percent weight loss), body composition, metabolic and iron changes assessed at baseline, 6 and 12 months.

DATA

mean (95% CI). In HP completers at 6 months, percent weight loss was higher [HP: 9.3 (5.6-13.1); HC: 5.1 (2.3-7.9)%; p = 0.06]; although, this did not reach statistical significance. Absolute weight [HP: 8.9 (5.3-12.5); HC: 4.6 (2.2-7.0) kg; p = 0.034] and fat loss [HP: 8.0 (4.4-11.5); HC: 3.4 (1.3-5.6) kg; p = 0.022] were significantly greater. No significant between-diet differences were observed at 12 months. Biochemistry remained within normal ranges with HP showing superior preservation of ferritin at 6 months [HP: 53 (40-66); HC: 46 (30-61) µg/l; p = 0.029]. Both diets supported clinically meaningful weight loss with HP tending to be more effective in the medium-term.

Human Aortic Endothelial Cell Labeling with Positive Contrast Gadolinium Oxide Nanoparticles for Cellular Magnetic Resonance Imaging at 7 Tesla

Positive T1 contrast using gadolinium (Gd) contrast agents can potentially improve detection of labeled cells on magnetic resonance imaging (MRI). Recently, gadolinium oxide (Gd2O3) nanoparticles have shown promise as a sensitive T1 agent for cell labeling at clinical field strengths compared to conventional Gd chelates. The objective of this study was to investigate Gado CELLTrack, a commercially available Gd2O3 nanoparticle, for cell labeling and MRI at 7 T. Relaxivity measurements yielded r1 = 4.7 s−1 mM−1 and r2/ r1 = 6.2. Human aortic endothelial cells were labeled with Gd2O3 at various concentrations and underwent MRI from 1 to 7 days postlabeling. The magnetic resonance relaxation times T1 and T2 of labeled cell pellets were measured. Cellular contrast agent uptake was quantified by inductively coupled plasma–atomic emission spectroscopy, which showed very high uptake compared to conventional Gd compounds. MRI demonstrated significant positive T1 contrast and stable labeling on cells. Enhancement was optimal at low Gd concentrations, attained in the 0.02 to 0.1 mM incubation concentration range (corresponding cell uptake was 7.26 to 34.1 pg Gd/cell). Cell viability and proliferation were unaffected at the concentrations tested and up to at least 3 days postlabeling. Gd2O3 is a promising sensitive and stable positive contrast agent for cellular MRI at 7 T.

The relationship between obesity and hypoferraemia in adults: a systematic review

A growing number of studies suggest a potential link between obesity and altered iron metabolism. The purpose of this systematic review was to examine existing literature on iron status in obese populations. A comprehensive literature search was conducted. Included studies recruited participants ≥ 18 years with a body mass index ≥ 30 kg m(-2) and provided descriptive statistics for haemoglobin or ferritin at a minimum. There were 25 studies meeting all eligibility criteria, of these 10 examined iron status in free-living obese individuals and 15 reported baseline iron biomarkers from bariatric surgery candidates. Non-obese comparison groups were used by 10 (40%) articles. In these, seven obese groups reported higher mean haemoglobin concentration; six reported significantly higher ferritin concentration; and four significantly lower transferrin saturation. Due to insufficient data, it was not possible to make conclusions regarding mean differences for soluble transferrin receptor (sTfR), hepcidin or C-reactive protein. Existing evidence suggests a tendency for higher haemoglobin and ferritin concentration and lower transferrin saturation in obesity. Alternation of iron biomarkers in obese populations may be a result of obesity-related inflammation and/or related comorbidities. Further research incorporating measurement of inflammatory cytokines, sTfR and hepcidin is required to confirm the impact of obesity on iron status.

ATM damage response and XLF repair factor are functionally redundant in joining DNA breaks

Classical non-homologous DNA end-joining (NHEJ) is a major mammalian DNA double-strand-break (DSB) repair pathway. Deficiencies for classical NHEJ factors, such as XRCC4, abrogate lymphocyte development, owing to a strict requirement for classical NHEJ to join V(D)J recombination DSB intermediates. The XRCC4-like factor (XLF; also called NHEJ1) is mutated in certain immunodeficient human patients and has been implicated in classical NHEJ; however, XLF-deficient mice have relatively normal lymphocyte development and their lymphocytes support normal V(D)J recombination. The ataxia telangiectasia-mutated protein (ATM) detects DSBs and activates DSB responses by phosphorylating substrates including histone H2AX. However, ATM deficiency causes only modest V(D)J recombination and lymphocyte developmental defects, and H2AX deficiency does not have a measurable impact on these processes. Here we show that XLF, ATM and H2AX all have fundamental roles in processing and joining DNA ends during V(D)J recombination, but that these roles have been masked by unanticipated functional redundancies. Thus, combined deficiency of ATM and XLF nearly blocks mouse lymphocyte development due to an inability to process and join chromosomal V(D)J recombination DSB intermediates. Combined XLF and ATM deficiency also severely impairs classical NHEJ, but not alternative end-joining, during IgH class switch recombination. Redundant ATM and XLF functions in classical NHEJ are mediated by ATM kinase activity and are not required for extra-chromosomal V(D)J recombination, indicating a role for chromatin-associated ATM substrates. Correspondingly, conditional H2AX inactivation in XLF-deficient pro-B lines leads to V(D)J recombination defects associated with marked degradation of unjoined V(D)J ends, revealing that H2AX has a role in this process.

Elements between the IgH variable (V) and diversity (D) clusters influence antisense transcription and lineage-specific V(D)J recombination

Ig and T-cell receptor (TCR) variable-region gene exons are assembled from component variable (V), diversity (D) and joining (J) gene segments during early B and T cell development. The RAG1/2 endonuclease initiates V(D)J recombination by introducing DNA double-strand breaks at borders of the germ-line segments. In mice, the Ig heavy-chain (IgH) locus contains, from 5' to 3', several hundred V(H) gene segments, 13 D segments, and 4 J(H) segments within a several megabase region. In developing B cells, IgH variable-region exon assembly is ordered with D to J(H) rearrangement occurring on both alleles before appendage of a V(H) segment. Also, IgH V(H) to DJ(H) rearrangement does not occur in T cells, even though DJ(H) rearrangements occur at low levels. In these contexts, V(D)J recombination is controlled by modulating substrate gene segment accessibility to RAG1/2 activity. To elucidate control elements, we deleted the 100-kb intergenic region that separates the V(H) and D clusters (generating ΔV(H)-D alleles). In both B and T cells, ΔV(H)-D alleles initiated high-level antisense and, at lower levels, sense transcription from within the downstream D cluster, with antisense transcripts extending into proximal V(H) segments. In developing T lymphocytes, activated germ-line antisense transcription was accompanied by markedly increased IgH D-to-J(H) rearrangement and substantial V(H) to DJ(H) rearrangement of proximal IgH V(H) segments. Thus, the V(H)-D intergenic region, and likely elements within it, can influence silencing of sense and antisense germ-line transcription from the IgH D cluster and thereby influence targeting of V(D)J recombination.

Diode-pumped passively mode-locked 1,342 nm Nd:YVO4 laser with an AlGaInAs quantum-well saturable absorber

We demonstrate what we believe to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber for a diode-pumped passively mode locked Nd:YVO(4) laser at 1342 nm. The QWs are grown on a Fe-doped InP substrate that is transparent at lasing wavelength. At an incident pump power of 13.5 W an average output power of 1.05 W with a continuous mode-locked pulse duration of 26.4 ps at a repetition rate of 152 MHz was generated.

Lymphocyte-specific compensation for XLF/cernunnos end-joining functions in V(D)J recombination

Mutations in XLF/Cernunnos (XLF) cause lymphocytopenia in humans, and various studies suggest an XLF role in classical nonhomologous end joining (C-NHEJ). We now find that XLF-deficient mouse embryonic fibroblasts are ionizing radiation (IR) sensitive and severely impaired for ability to support V(D)J recombination. Yet mature lymphocyte numbers in XLF-deficient mice are only modestly decreased. Moreover, XLF-deficient pro-B lines, while IR-sensitive, perform V(D)J recombination at nearly wild-type levels. Correspondingly, XLF/p53-double-deficient mice are not markedly prone to the pro-B lymphomas that occur in previously characterized C-NHEJ/p53-deficient mice; however, like other C-NHEJ/p53-deficient mice, they still develop medulloblastomas. Despite nearly normal V(D)J recombination in developing B cells, XLF-deficient mature B cells are moderately defective for immunoglobulin heavy-chain class switch recombination. Together, our results implicate XLF as a C-NHEJ factor but also indicate that developing mouse lymphocytes harbor cell-type-specific factors/pathways that compensate for the absence of XLF function during V(D)J recombination.

Tissue-specific regulation of SIRT1 by calorie restriction

Calorie restriction (CR) has been reported to increase SIRT1 protein levels in mice, rats, and humans, and elevated activity of SIRT1 orthologs extends life span in yeast, worms, and flies. In this study, we challenge the paradigm that CR induces SIRT1 activity in all tissues by showing that activity of this sirtuin in the liver is, in fact, reduced by CR and activated by a high-caloric diet. We demonstrate this change both by assaying levels of SIRT1 and its small molecule regulators, NAD and NADH, as well as assessing phenotypes of a liver-specific SIRT1 knockout mouse on various diets. Our findings suggest that designing CR mimetics that target SIRT1 to provide uniform systemic benefits may be more complex than currently imagined.

Tissue-specific regulation of SIRT1 by calorie restriction

Calorie restriction (CR) has been reported to increase SIRT1 protein levels in mice, rats, and humans, and elevated activity of SIRT1 orthologs extends life span in yeast, worms, and flies. In this study, we challenge the paradigm that CR induces SIRT1 activity in all tissues by showing that activity of this sirtuin in the liver is, in fact, reduced by CR and activated by a high-caloric diet. We demonstrate this change both by assaying levels of SIRT1 and its small molecule regulators, NAD and NADH, as well as assessing phenotypes of a liver-specific SIRT1 knockout mouse on various diets. Our findings suggest that designing CR mimetics that target SIRT1 to provide uniform systemic benefits may be more complex than currently imagined.

Mammalian Sir2 homolog SIRT3 regulates global mitochondrial lysine acetylation

Homologs of the Saccharomyces cerevisiae Sir2 protein, sirtuins, promote longevity in many organisms. Studies of the sirtuin SIRT3 have so far been limited to cell culture systems. Here, we investigate the localization and function of SIRT3 in vivo. We show that endogenous mouse SIRT3 is a soluble mitochondrial protein. To address the function and relevance of SIRT3 in the regulation of energy metabolism, we generated and phenotypically characterized SIRT3 knockout mice. SIRT3-deficient animals exhibit striking mitochondrial protein hyperacetylation, suggesting that SIRT3 is a major mitochondrial deacetylase. In contrast, no mitochondrial hyperacetylation was detectable in mice lacking the two other mitochondrial sirtuins, SIRT4 and SIRT5. Surprisingly, despite this biochemical phenotype, SIRT3-deficient mice are metabolically unremarkable under basal conditions and show normal adaptive thermogenesis, a process previously suggested to involve SIRT3. Overall, our results extend the recent finding of lysine acetylation of mitochondrial proteins and demonstrate that SIRT3 has evolved to control reversible lysine acetylation in this organelle.

Defective DNA repair and increased genomic instability in Cernunnos-XLF-deficient murine ES cells

Nonhomologous DNA end-joining (NHEJ) is a major pathway of DNA double-strand break (DSB) repair in mammalian cells, and it functions to join both specifically programmed DSBs that occur in the context of V(D)J recombination during early lymphocyte development as well as general DSBs that occur in all cells. Thus, defects in NHEJ impair V(D)J recombination and lead to general genomic instability. In human patients, mutations of Cernunnos-XLF (also called NHEJ1), a recently identified NHEJ factor, underlie certain severe combined immune deficiencies associated with defective V(D)J recombination and radiosensitivity. To characterize Cernunnos-XLF function in mouse cells, we used gene-targeted mutation to delete exons 4 and 5 from both copies of the Cernunnos-XLF gene in ES cell (referred to as Cer(Delta/Delta) ES cells). Analyses of Cer(Delta/Delta) ES cells showed that they produce no readily detectable Cernunnos-XLF protein. Based on transient V(D)J recombination assays, we find that Cer(Delta/Delta) ES cells have dramatic impairments in ability to form both V(D)J coding joins and joins of their flanking recombination signal sequences (RS joins). Cer(Delta/Delta) ES cells are highly sensitive to ionizing radiation and have intrinsic DNA DSB repair defects as measured by pulse field gel electrophoresis. Finally, the Cernunnos-XLF mutations led to increased spontaneous genomic instability, including translocations. We conclude that, in mice, Cernunnos-XLF is essential for normal NHEJ-mediated repair of DNA DSBs and that Cernunnos-XLF acts as a genomic caretaker to prevent genomic instability.

Cholinergic-receptor-independent dysfunction of mitochondrial respiratory chain enzymes, reduced mitochondrial transmembrane potential and ATP depletion underlie necrotic cell death induced by the organophosphate poison mevinphos

Our current understanding of the nature of cell death that is associated with fatal organophosphate poisoning and the underlying cellular mechanisms is surprisingly limited. Taking advantage of the absence in an in vitro system of acetylcholinesterase, the pharmacological target of organophosphate compounds, the present study evaluated the hypothesis that the repertoire of cholinergic receptor-independent cellular events that underlie fatal organophosphate poisoning entails induction of mitochondrial dysfunction, followed by bioenergetic failure that leads to necrotic cell death because of ATP depletion. Pheochromocytoma PC12 cells incubated with the organophosphate pesticide mevinphos (0.4 or 4mumol) for 1 or 3h underwent a dose-related and time-dependent loss of cell viability that was not reversed by muscarinic (atropine) or nicotinic (mecamylamine) blockade. This was accompanied by depressed NADH cytochrome c reductase, succinate cytochrome c reductase or cytochrome c oxidase activity in the mitochondrial respiratory chain, reduced mitochondrial transmembrane potential, decreased ATP concentration, elevated ADP/ATP ratio, increased lactate dehydrogenase release and necrotic cell death. We conclude that Mev induces cholinergic receptor-independent necrotic cell death by depressing the activity of Complexes I to IV in the mitochondrial respiratory chain, eliciting reduction in mitochondrial transmembrane potential, depleting intracellular ATP contents and damaging cell membrane integrity.

Phytotoxicity of lanthanum in rice in haplic acrisols and cambisols

Growth and physiological responses of rice to lanthanum were studied to elucidate the function of lanthanum in plants and its critical concentration relative to environmental safety. Shoot La content increased with the increasing added La concentrations. When shoot La content exceeded a toxic value, plant growth and chlorophyll a/b decreased and peroxidase (POD) activity, cell membrane permeability, and content of proline in the leaf increased. Leaf chlorophyll a/b and POD activity might provide useful criteria for early diagnoses of phytotoxicity of soil contaminated by La. In the present study, the critical concentration of La for rice relative to environmental safety was suggested to be 42.03 mg kg(-1) in red soil and 83.33 mg kg(-1) in paddy soil.

SirT2 is a histone deacetylase with preference for histone H4 Lys 16 during mitosis

The mammalian cytoplasmic protein SirT2 is a member of the Sir2 family of NAD+-dependent protein deacetylases involved in caloric restriction-dependent life span extension. We found that SirT2 and its yeast counterpart Hst2 have a strong preference for histone H4K16Ac in their deacetylation activity in vitro and in vivo. We have pinpointed the decrease in global levels of H4K16Ac during the mammalian cell cycle to the G2/M transition that coincides with SirT2 localization on chromatin. Mouse embryonic fibroblasts (MEFs) deficient for SirT2 show higher levels of H4K16Ac in mitosis, in contrast to the normal levels exhibited by SirT1-deficient MEFs. The enzymatic conversion of H4K16Ac to its deacetylated form may be pivotal to the formation of condensed chromatin. Thus, SirT2 is a major contributor to this enzymatic conversion at the time in the cell's life cycle when condensed chromatin must be generated anew.

Genomic instability and aging-like phenotype in the absence of mammalian SIRT6

The Sir2 histone deacetylase functions as a chromatin silencer to regulate recombination, genomic stability, and aging in budding yeast. Seven mammalian Sir2 homologs have been identified (SIRT1-SIRT7), and it has been speculated that some may have similar functions to Sir2. Here, we demonstrate that SIRT6 is a nuclear, chromatin-associated protein that promotes resistance to DNA damage and suppresses genomic instability in mouse cells, in association with a role in base excision repair (BER). SIRT6-deficient mice are small and at 2-3 weeks of age develop abnormalities that include profound lymphopenia, loss of subcutaneous fat, lordokyphosis, and severe metabolic defects, eventually dying at about 4 weeks. We conclude that one function of SIRT6 is to promote normal DNA repair, and that SIRT6 loss leads to abnormalities in mice that overlap with aging-associated degenerative processes.

Mammalian SIRT1 limits replicative life span in response to chronic genotoxic stress

The Saccharomyces cerevisiae chromatin silencing factor Sir2 suppresses genomic instability and extends replicative life span. In contrast, we find that mouse embryonic fibroblasts (MEFs) deficient for SIRT1, a mammalian Sir2 homolog, have dramatically increased resistance to replicative senescence. Extended replicative life span of SIRT1-deficient MEFs correlates with enhanced proliferative capacity under conditions of chronic, sublethal oxidative stress. In this context, SIRT1-deficient cells fail to normally upregulate either the p19(ARF) senescence regulator or its downstream target p53. However, upon acute DNA damage or oncogene expression, SIRT1-deficient cells show normal p19(ARF) induction and cell cycle arrest. Together, our findings demonstrate an unexpected SIRT1 function in promoting replicative senescence in response to chronic cellular stress and implicate p19(ARF) as a downstream effector in this pathway.

Phasic cardiovascular responses to mevinphos are mediated through differential activation of cGMP/PKG cascade and peroxynitrite via nitric oxide generated in the rat rostral ventrolateral medulla by NOS I and II isoforms

The organophosphate insecticide mevinphos (Mev) acts on the rostral ventrolateral medulla (RVLM), where sympathetic vasomotor tone originates, to elicit phasic cardiovascular responses via nitric oxide (NO) generated by NO synthase (NOS) I and II. We evaluated the contribution of soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) cascade and peroxynitrite in this process. PKG expression in ventrolateral medulla of Sprague-Dawley rats manifested an increase during the sympathoexcitatory phase (Phase I) of cardiovascular responses induced by microinjection of Mev bilaterally into the RVLM that was antagonized by co-administration of 7-nitroindazole or Nomega-propyl-L-arginine, two selective NOS I inhibitors or 1-H-[1,2,4]oxadiaolo[4,3-a]quinoxalin-1-one (ODQ), a selective sGC antagonist. Co-microinjection of ODQ or two PKG inhibitors, KT5823 or Rp-8-Br-cGMPS, also blunted the Mev-elicited sympathoexcitatory effects. However, the increase in nitrotyrosine, a marker for peroxynitrite, and the sympathoinhibitory circulatory actions during Phase II Mev intoxication were antagonized by co-administration of S-methylisothiourea, a selective NOS II inhibitor, Mn(III)-tetrakis-(4-benzoic acid) porphyrin, a superoxide dismutase mimetic, 5,10,15,20-tetrakis-N-methyl-4'-pyridyl)-porphyrinato iron (III), a peroxynitrite decomposition catalyst, or L-cysteine, a peroxynitrite scavenger. We conclude that sGC/cGMP/PKG cascade and peroxynitrite formation may participate in Mev-induced phasic cardiovascular responses as signals downstream to NO generated respectively by NOS I and II in the RVLM.

Stress-dependent regulation of FOXO transcription factors by the SIRT1 deacetylase

The Sir2 deacetylase modulates organismal life-span in various species. However, the molecular mechanisms by which Sir2 increases longevity are largely unknown. We show that in mammalian cells, the Sir2 homolog SIRT1 appears to control the cellular response to stress by regulating the FOXO family of Forkhead transcription factors, a family of proteins that function as sensors of the insulin signaling pathway and as regulators of organismal longevity. SIRT1 and the FOXO transcription factor FOXO3 formed a complex in cells in response to oxidative stress, and SIRT1 deacetylated FOXO3 in vitro and within cells. SIRT1 had a dual effect on FOXO3 function: SIRT1 increased FOXO3's ability to induce cell cycle arrest and resistance to oxidative stress but inhibited FOXO3's ability to induce cell death. Thus, one way in which members of the Sir2 family of proteins may increase organismal longevity is by tipping FOXO-dependent responses away from apoptosis and toward stress resistance.

Developmental defects and p53 hyperacetylation in Sir2 homolog (SIRT1)-deficient mice

SIRT1 is a mammalian homolog of the Saccharomyces cerevisiae chromatin silencing factor Sir2. Dominant-negative and overexpression studies have implicated a role for SIRT1 in deacetylating the p53 tumor suppressor protein to dampen apoptotic and cellular senescence pathways. To elucidate SIRT1 function in normal cells, we used gene-targeted mutation to generate mice that express either a mutant SIRT1 protein that lacks part of the catalytic domain or has no detectable SIRT1 protein at all. Both types of SIRT1 mutant mice and cells had essentially the same phenotypes. SIRT1 mutant mice were small, and exhibited notable developmental defects of the retina and heart, and only infrequently survived postnatally. Moreover, SIRT1-deficient cells exhibited p53 hyperacetylation after DNA damage and increased ionizing radiation-induced thymocyte apoptosis. In SIRT1-deficient embryonic fibroblasts, however, p53 hyperacetylation after DNA damage was not accompanied by increased p21 protein induction or DNA damage sensitivity. Together, our observations provide direct evidence that endogenous SIRT1 protein regulates p53 acetylation and p53-dependent apoptosis, and show that the function of this enzyme is required for specific developmental processes.

Extrachromosomal recombination substrates recapitulate beyond 12/23 restricted VDJ recombination in nonlymphoid cells

V(D)J recombination occurs efficiently only between gene segments flanked by recombination signals (RSs) containing 12 and 23 base pair spacers (the 12/23 rule). A further limitation "beyond the 12/23 rule" (B12/23) exists at the TCRbeta locus and ensures Dbeta usage. Herein, we show that extrachromosomal V(D)J recombination substrates recapitulate B12/23 restriction in nonlymphoid cells. We further demonstrate that the Vbeta coding flank, the 12-RS heptamer/nonamer, and the 23-RS spacer each can significantly influence B12/23 restriction. Finally, purified core RAG1 and RAG2 proteins (together with HMG2) also reproduce B12/23 restriction in a cell-free system. Our findings indicate that B12/23 restriction of V(D)J recombination is cemented at the level of interactions between the RAG proteins and TCRbeta RS sequences.

Transurethral microwave thermotherapy for symptomatic benign prostatic hyperplasia: long-term durability with Prostcare

OBJECTIVE

To evaluate the long-term durability of transurethral microwave thermotherapy (TUMT) with Prostcare for symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

From August 1993 to July 1994, a total of 65 patients with symptomatic BPH who underwent TUMT using the Prostcare apparatus (Bruker Spectospin, Wissembourg, France) with low-energy protocol (maximal power 52 W) were enrolled into a short-term evaluation. Subsequent follow-up information was collected in July 1999. If patients had had any further therapy for BPH, the date of retreatment was considered as an endpoint of TUMT efficacy. If no further therapy for BPH had been needed, they were re-assessed for overall satisfaction.

RESULTS

The median follow-up period was 49 months. Twenty patients were excluded for various reasons, including 17 with loss of follow-up and 3 with new diseases that could affect the voiding status. Thirty-eight (84.4%) of 45 valuable patients had received further therapy for BPH, including medication (n = 21, 46.7%), and endoscopic surgery (n = 17, 37.7%). The times to pharmacologic or endoscopic retreatment after TUMT were 8.9+/-11.1 and 23.0+/-14.4 months, respectively (p = 0.0003, log rank test). Only 7 (15.5%) patients had no further treatment, with 3 having satisfactory improvements, but 4 feel dissatisfied yet not needing any further therapy. In addition, 2 patients complained of erectile dysfunction after TUMT and 1 was diagnosed with prostate cancer 50 months after TUMT. In addition, there was no significant difference for all baseline values among three groups with no retreatment or retreatment with medication or endoscopic surgery.

CONCLUSION

At the 5-year follow-up, the long-term durability of low-energy TUMT with Prostcare is only exhibited in a few patients and the overall retreatment rate was 84.4%. Thus, patient should be informed of the high probability of supplementary treatment after TUMT.

Functional effects of casein kinase I-catalyzed phosphorylation on lens cell-to-cell coupling

The functional consequence of the casein kinase I-catalyzed phosphorylation of the lens gap junctional protein connexin49 was investigated using a sheep primary lens cell culture system. To determine whether the phosphorylation of connexin49 catalyzed by endogenous casein kinase I results in an altered junctional communication between lens cells, the effect of the casein kinase I-specific inhibitor CKI-7 on Lucifer Yellow dye transfer between cells in the lens culture was examined. Dye transfer was analyzed in cultures of different ages because we have demonstrated previously that the expression of connexin49 increases as the cultures age while that of connexin43, which is likely not a substrate for casein kinase I, has been shown to decrease [Yang & Louis (1999) Invest. Ophthalmol. Vis. Sci. 41: 2568-2564]. In 9-day old lens cultures, in which gap junctions are composed primarily of connexin43, CKI-7 had little effect on the rate of dye transfer between lens cells. In contrast, treatment of 15-day and 28-day old cultures with CKI-7 resulted in a significant increase in the rate of dye transfer. Thus, the extent of this CKI-7-dependent increase in cell-to-cell communication was positively correlated with the level of expression of connexin49, the major casein kinase I substrate in lens plasma membranes. These results suggest that the casein kinase I-catalyzed phosphorylation of connexin49 decreases cell communication between connexin49-containing gap junctions in the lens.

Proton-lithium binding behavior of tris(2-((pyrid-2-ylmethyl)uredio)ethyl)amine

Tris(2-((pyrid-2-ylmethyl)uredio)ethyl)amine (2) and its perchlorate salt, 2.HClO(4), bind with Li+ in nitromethane in a 1:1 fashion. The stability constants of K(Li+) and K(H)(Li+) were found to be 112 +/- 25 and 130 +/- 30 M(-)(1) in CD(3)NO(2), respectively. Formation of the 1:1 complexes were further evidenced by electrospray ionization mass spectrometry (ESI-MS). The slight increase, or at least the same order of magnitude, of K(H)(Li+) compared to K(Li+) points to a remarkable preorganization of the protonated podand in 2.HClO(4), that essentially overcomes the increased Columbic repulsion occurring on complexation to Li+.

Role of beta 2-microglobulinuria and microalbuminuria in pediatric febrile urinary tract infection

Urinary beta-2-microglobulin (beta 2M) and microalbumin concentrations were analyzed in 61 pediatric patients with febrile urinary tract infection (UTI). The results were compared with those of technetium-99m-labeled dimercaptosuccinic acid (99mTc-DMSA) single photon emission computed tomography (SPECT) imaging. Noninvasive evaluations were made to localize the site of the UTI. Increased urinary beta 2M/Creatinine (Cr) or microalbumin/Cr quotients were not associated with renal inflammation, as defined by a positive renal scan. Increased urinary microalbumin/Cr is associated with UTI in febrile patients regardless of the level of infection (scan status), and may be an informative indicator of UTI. When microalbumin/Cr was > or = 0.03, its sensitivity and specificity to predict UTI in febrile patients, regardless of the site of the infection, were 95.65% and 51.79%, respectively, and its positive predictive value was 62.0%. On the other hand, urinary beta 2M/Cr (> or = 0.13) demonstrates a statistically significant correlation with the presentation of a high grade of vesicoureteral reflux (p = 0.02). We suggest that a prompt renal imaging study is warranted when the urinary beta 2M/Cr ratio is high (> or = 0.13).

Video-assisted thoracoscopic surgery for the diagnosis of patients with hilar and mediastinal lymphadenopathy

In areas where tuberculosis (TB) is rare, cases of hilar and mediastinal lymphadenopathy are often attributed to the diagnosis of sarcoidosis or a malignant process. However, these manifestations have been only sparsely reported in countries with high rates of TB. The role of simultaneous lung biopsy in the differential diagnosis of these patients using a thoracoscopic approach is also undetermined. In this prospective study, 15 adult patients with hilar and mediastinal lymphadenopathy were evaluated using video-assisted thoracoscopy during the period from May 1995 through September 1999. Biopsy of the hilar and mediastinal lymph nodes was undertaken in all 15 patients, and a wedge biopsy of the lungs was performed whenever frozen section of the nodes disclosed granulomatous inflammation. The final diagnoses included sarcoidosis (10 patients), TB (2), metastatic small cell carcinoma (2), and reactive lymphoid hyperplasia (1). No morbidity or mortality was associated with the operation. In patients with sarcoidosis and TB, most of the lymph node biopsy specimens disclosed extensive hyaline fibrosis. Lung biopsy specimens presented small non-necrotizing granulomas with multinucleated giant cells even in the absence of demonstrable parenchymal lesions. In the two patients with TB, identification of acid-fast bacilli and growth of Mycobacterium tuberculosis occurred only in lung specimens and not in specimens from lymph nodes. Video-assisted thoracoscopic surgery is a safe, simple, and effective procedure for the diagnosis of patients with hilar and mediastinal lymphadenopathy. Our results suggest that for a better differentiation between TB and sarcoidosis, an additional lung biopsy could be undertaken to provide specimens for microscopic examination and culture.

Transurethral microwave thermotherapy for symptomatic benign prostatic hyperplasia: short-term experience with Prostcare

PURPOSE

To assess our short-term experience with transurethral microwave thermotherapy (TUMT) for symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

From August 1993 through July 1994, in total 65 patients with symptomatic BPH were enrolled into this study. The patients' ages ranged from 56 to 95 years with a mean of 70 years. Under local anesthesia with intraurethral instillation of Xylocaine jelly only, all patients received one session of TUMT for up to 60 min with Prostcare equipment. Uroflowmetry was performed and international prostatic symptom score (IPSS) determined before 3 and 6 months after TUMT for assessment of efficacy. All adverse events were recorded and evaluated for clinical relevance.

RESULTS

At 3 and 6 months following TUMT, the mean IPSS decreased from 19.7 +/- 6.8 (baseline) to 12.8 +/- 8.2 (-46%) and to 15.5 +/- 9.0 (-21%), respectively; the maximal urine flow rate at 3 and 6 months increased from 9.1 +/- 4.8 ml/s (baseline) to 11.0 +/- 4.9 ml/s (+21%) and to 10.9 +/- 5.6 ml/s (+19%), respectively. During TUMT, burning sensation was the most frequent complaint (38.5%), followed by urethral discomfort (29.2%) and urgency (9.2%). Two patients (3.1%) interrupted TUMT, because of intolerable pain. Following TUMT micturition pain (73.8%) and gross hematuria (45.9%) were the most adverse events. Most of these adverse events disappeared within 2 weeks. One patient suffered from skin erosion over the penoscrotal junction 1 week later. None had retrograde ejaculation; 1 patient complained of erectile dysfunction.

CONCLUSION

Although the efficacy of TUMT with Prostcare became less prominent 6 months after TUMT, TUMT was still a tolerable, safe alternative treatment of BPH, especially in patients who were not suitable for transurethral resection of the prostate or anesthesia.

Insulin-like growth factor-I and over-expression of Bcl-xL prevent glucose-mediated apoptosis in Schwann cells

Schwann cells (SCs), the myelinating cells of the peripheral nervous system, are lost or damaged in patients suffering from diabetic neuropathy. In the current study, 2 model systems are used to study the mechanism of SC damage in diabetic neuropathy: the streptozotocin (STZ)-treated diabetic rat and cultures of purified SCs in vitro. Electron microscopy of dorsal root ganglia from STZ-treated rats reveals classic ultrastructural features of apoptosis in SCs, including chromatin clumping and prominent vacuolation. Bisbenzamide staining of SCs cultured in hyperglycemic defined media shows nuclear blebbing of apoptotic cells. Insulin-like growth factor-I (IGF-I) is protective. LY294002, a phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, blocks the effect of IGF-I. High glucose induces caspase cleavage in apoptotic SCs--an effect that is blocked by bok-asp-fmk (BAF), a caspase inhibitor. Although Bcl-xL expression remains unchanged in experimental conditions, over-expression of Bcl-xL protects SCs from apoptosis. In summary, hyperglycemia induces caspase activation and morphologic changes in SCs consistent with apoptotic death, both in vivo and in vitro. Over-expression of Bcl-xL, or IGF-I, signaling via PI 3-kinase, protects SCs from glucose-mediated apoptosis in vitro. IGF-I may be useful in preventing hyperglycemia-induced damage to SCs in patients suffering from diabetic neuropathy.

Insulin-like growth factor-I and Bcl-X(L) inhibit c-jun N-terminal kinase activation and rescue Schwann cells from apoptosis

We previously reported that Schwann cells undergo apoptosis after serum withdrawal. Insulin-like growth factor-I, via phosphatidylinositol-3 kinase, inhibits caspase activation and rescues Schwann cells from serum withdrawal-induced apoptosis. In this study, we examined the role of c-jun N-terminal protein kinase (JNK) in Schwann cell apoptosis induced by serum withdrawal. Activation of both JNK1 and JNK2 was detected 1 h after serum withdrawal with the maximal level detected at 2 h. A dominant negative JNK mutant, JNK (APF), blocked JNK activation induced by serum withdrawal and Schwann cell apoptosis, suggesting JNK activation participates in Schwann cell apoptosis. Serum withdrawal-induced JNK activity was caspase dependent and inhibited by a caspase 3 inhibitor, Ac-DEVD-CHO. Because insulin-like growth factor-I and Bcl-X(L) are both Schwann cell survival factors, we tested their effects on JNK activation during apoptosis. Insulin-like growth factor-I treatment decreased both JNK1 and JNK2 activity induced by serum withdrawal. LY294002, a phosphatidylinositol-3 kinase inhibitor, blocked insulin-like growth factor-I inhibition on JNK activation, suggesting that phosphatidylinositol-3 kinase mediates the effects of insulin-like growth factor-I. Overexpression of Bcl-X(L) also resulted in less Schwann cell death and inhibition of JNK activation after serum withdrawal. Collectively, these results suggest JNK activation is involved in Schwann cell apoptosis induced by serum withdrawal. Insulin-like growth factor-I and Bcl family proteins rescue Schwann cells, at least in part, by inhibition of JNK activity.

Expression of nm23-H1 in transitional cell carcinoma of the upper urinary tract

Transitional cell carcinoma of the upper urinary tract is an uncommon neoplasm. Relatively little information is available regarding the clinical relevance of molecular markers. This study was performed to examine the importance of nm23-H1 gene expression (NM23-H1) in this type of tumors. Immunohistochemical expression of NM23-H1 was analyzed in 90 cases of upper urinary tract cancer, and was compared for its prognostic significance with conventional biological indicators. High expression of NM23-H1 was found in 7 cases (8%), intermediate expression in 32 cases (36%), and low expression in 51 cases (57%). Reduced NM23-H1 (defined as intermediate or low level of expression) was associated with a higher histological grading (p=0.002), invasive tumor growth (p=0. 002), or an increased proliferating cell nuclear antigen labeling index (p=0.004). NM23-H1 tended to inversely relate to later recurrence or long-term survival (p=0.06), but, only tumor staging was found to be significant in predicting clinical outcome (p=0.002). nm23-H1 appears to function as a tumor suppressor for upper urinary tract cancer, however, evaluation of NM23-H1 provides limited prognostic information.

Analysis of synthetic chemical drugs in adulterated Chinese medicines by capillary electrophoresis/electrospray ionization mass spectrometry

Sixteen synthetic chemical drugs, often found in adulterated Chinese medicines, were studied by capillary electrophoresis/UV absorbance (CE/UV) and capillary electrophoresis/electrospray ionization mass spectrometry (CE/ESI-MS). Only nine peaks were detected with CZE/UV, but on-line CZE/MS provided clear identification for most compounds. For a real sample of a Chinese medicinal preparation, a few adulterants were identified by their migration times and protonated molecular ions. For coeluting compounds, more reliable identification was achieved by MS/MS in selected reaction monitoring mode. Micellar electrokinetic chromatography (MEKC) using sodium dodecyl sulfate (SDS) provided better separation than capillary zone electrophoresis (CZE), and, under optimal conditions, fourteen peaks were detected using UV detection. In ESI, the interference of SDS was less severe in positive ion mode than in negative ion mode. Up to 20 mM SDS could be used in direct coupling of MEKC with ESI-MS if the mass spectrometer was operated in positive ion mode. Because of better resolution in MEKC, adulterants can be identified without the use of MS/MS.

IGF-I promotes Schwann cell motility and survival via activation of Akt

We previously reported insulin-like growth factor-I (IGF-I) promotes Schwann cell (SC) motility and rescues SC from apoptosis induced by serum deprivation. This effect is mediated by phosphatidylinositol-3 (PI-3) kinase. In the current study, we examined the role of Akt, a downstream kinase of PI-3K, in SC motility and IGF-I mediated protection from apoptosis. IGF-I induces Akt phosphorylation at Ser473, an event which may be blocked by pretreatment with a PI-3K inhibitor, LY294002. In dominant negative K179M Akt (K179M) transfected SC, however, Akt is not activated in response to IGF-I. In addition, IGF-I is unable to promote SC motility and survival in K179M SC. These results suggest a critical role for Akt in IGF-I mediated motility and survival in SC.

GTPases and phosphatidylinositol 3-kinase are critical for insulin-like growth factor-I-mediated Schwann cell motility

Previously, we reported insulin-like growth factor-I (IGF-I) promotes motility and focal adhesion kinase (FAK) activation in neuronal cells. In the current study, we examined the role of IGF-I in Schwann cell (SC) motility. IGF-I increases SC process extension and motility. In parallel, IGF-I activates IGF-I receptor, insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3 (PI-3)-kinase, and FAK. LY294002, a PI-3 kinase inhibitor, blocks IGF-I-induced motility and FAK phosphorylation. The Rho family of GTPases is important in the regulation of the cytoskeleton. Overexpression of constitutively active Leu-61 Cdc42 and Val-12 Rac1 enhances SC motility which is unaffected by LY294002. In parallel, stable transfection of SC with dominant negative Asn-17 Rac1 blocks IGF-I-mediated SC motility and FAK phosphorylation, implying Rac is an upstream regulator of FAK. Collectively our results suggest that IGF-I regulates SC motility by reorganization of the actin cytoskeleton via the downstream activation of a PI-3 kinase, small GTPase, and FAK pathway.

Insulin-like growth factor-I promotes myelination of peripheral sensory axons

Insulin-like growth factor-I (IGF-I) in vivo or in the presence of other permissive factors can promote myelination in the central nervous system. In the current study, we examine the role of IGF-I in the myelination of peripheral nerves. In rat cocultures of dorsal root ganglia (DRG) and Schwann cells (SC) grown in serum- and insulin-free defined medium, IGF-I induces a dose dependent upregulation in myelin proteins such as P0, corresponding to maximal SC ensheathment. Furthermore, IGF-I is essential in promoting a dose-dependent, long-term myelination of DRG sensory axons. In the absence of IGF-I, axons and SC survive, but fail to myelinate. In the presence of 10 nM IGF-I, 59% of axons are myelinated at 21 days, whereas in the absence of IGF-I myelination fails to occur. Maximum SC ensheathment occurs 48 hours after addition of IGF-I. If IGF-I is withdrawn at 48 hours, axon segregation by SC persists, however, most axons and SC do not exhibit a one-to-one relationship and little myelination is observed. IGF-I is important in myelination and is critical not only for initial SC ensheathment of the axon and upregulation of myelin proteins, but also for sustained myelination. Furthermore, IGF-I associated axonal size is not the sole determinant for myelination.

The clinical value of p21WAF1/CIP1 expression in superficial bladder cancer

The clinical value of p21WAF1/CIP1 in superficial bladder cancer remains controversial. To address the question, we examined the expression patterns of p21 and p53 gene products and compared for their significance in a total of 89 cases of superficial (pTa/pT1) bladder cancer. Over-expression of p21 was detected in 32 of 89 (36%) tumors. But, the expression status did not correlate with biological indicators or clinical outcome (p > 0.1, respectively). Factors predicting clinical outcome were multiplicity for tumor recurrence (p = 0.0002) or patient survival (p = 0.03), and the histological grading for disease progression (p = 0.02) or patient survival (p = 0.05). Taking into account the p53 status, a trend approaching better prognosis for p53+p21+ tumors was observed compared with that of p53+p21- bladder cancer (p = 0.08). Our data indicate that evaluation of p21 status does not provide better prognostic information compared with conventional biological indicators of superficial bladder cancer. Maintenance of p21 appears to abrogate the deleterious effects of p53 alterations in the tumorigenesis of human bladder.

Transitional cell carcinoma in dialysis patients

OBJECTIVE

The aim of our study was to determine whether there is an increased incidence of urothelial cancer, especially transitional cell carcinoma (TCC), in uremic patients on dialysis.

METHODS

Retrospective chart analyses were completed for 1,910 uremic patients undergoing maintenance dialysis between January 1987 and December 1997. The incidence of urinary tract cancer was assessed. Only the patients with cancers diagnosed after start of dialysis were enrolled in the study.

RESULTS

Of the 1,910 patients, 70 had concomitant urinary tract cancers. Nineteen patients (0.99%), including 17 patients with TCC and 2 patients with renal cell carcinoma, were diagnosed after the initiation of dialysis. The average duration from dialysis to TCC diagnosis was 38.3 (range 2-144) months. Painless gross hematuria was the cardinal symptom in 16 of the 17 patients with TCC. In the 17 patients with TCC, no distant metastases were found at the time of diagnosis. Fourteen patients (82.3%) were stage 0 or A, and 1 patient was stage B1.

CONCLUSIONS

The 0.89% incidence of TCC in our dialysis patients was high as compared with that of the general population. The risks of developing urinary TCC in dialysis patients were examined, and we suggest that immunosuppressive stage, dialysis procedure, and chronic bladder irritation (decreased urinary wash effect) may play a part in the development of urinary TCC in dialysis patients. Early detection of hematuria due to regular visits and decreased exposure of urinary tract epithelium to carcinogens from urine may explain why early-stage TCC was seen in most of our patients.

Insulin-like growth factor-I prevents caspase-mediated apoptosis in Schwann cells

Both neurons and glia succumb to programmed cell death (PCD) when deprived of growth factors at critical periods in development or following injury. Insulin-like growth factor-I (IGF-I) prevents apoptosis in neurons in vitro. To investigate whether IGF-I can protect Schwann cells (SC) from apoptosis, SC were harvested from postnatal day 3 rats and maintained in serum-containing media until confluency. When cells were switched to serum-free defined media (DM) for 12-72 h, they underwent PCD. Addition of insulin or IGF-I prevented apoptosis. Bisbenzamide staining revealed nuclear condensation and formation of apoptotic bodies in SC grown in DM alone, but SC grown in DM plus IGF-I had normal nuclear morphology. The phosphatidylinositol 3-kinase (PI 3-K) inhibitor LY294002 blocked IGF-I-mediated protection. Caspase-3 activity was rapidly activated upon serum withdrawal in SC, and the caspase inhibitor BAF blocked apoptosis. These results suggest that IGF-I rescues SC from apoptosis via PI 3-K signaling which is upstream from caspase activation.

Regulation of insulin-like growth factor-binding protein-5 expression during Schwann cell differentiation

We have reported that immortalized Schwann cells (SC) express the insulin-like growth factor I receptor and IGF-binding protein-5 (IGFBP-5). IGF-I promotes SC survival and protects IGFBP-5 in SC-conditioned medium from proteolysis. In the current study we examined the roles of IGF-I and IGFBP-5 in primary SC. IGF-I enhances primary SC differentiation and gene and protein expression of IGFBP-5 and the myelinating protein, P0. SC that stably overexpress human IGFBP-5 also have higher levels of P0 gene expression. The phosphatidylinositol-3 kinase inhibitor (LY294002), but not the mitogen-activated protein kinase kinase inhibitor (PD98059), blocks IGF-I enhancement of IGFBP-5 gene and protein expression. Collectively, these results suggest that IGF-I promotes SC differentiation, and this may occur in part by enhancing IGFBP-5 expression via phosphatidylinositol-3 kinase activation. These data support a link between enhanced IGFBP-5 expression and cellular differentiation.

IGF-I promotes peripheral nervous system myelination

Insulin-like growth factor-I (IGF-I) promotes the proliferation and differentiation of Schwann cells (SC). We use SC/dorsal root ganglion neuron (DRG) cocultures to examine the effects of IGF-I on the interaction between axons and SC. As SC extend processes toward the axon in the presence of IGF-I, these processes attach to and ensheath axons. Continued IGF-I exposure leads to enhanced P0 expression and long-term myelination. No myelination occurs in the absence of IGF-I. These data imply that IGF-I is critical not only for SC attachment and ensheathment of axons but also for long-term myelination.

Expression of vascular endothelial growth factor in primary superficial bladder cancer

BACKGROUND

Angiogenesis is of vital importance during the development and progression of solid tumors. This study was performed to test the clinical significance of vascular endothelial growth factor (VEGF) expression in primary superficial bladder cancer.

MATERIALS AND METHOD

A cohort of 185 cases of pTa/pT1 transitional cell bladder cancer and six cases of normal urothelium were studied by immunohistochemistry. Expression of VEGF was correlated with biological indicators of bladder cancer and examined for their prognostic value.

RESULTS

Variable amounts of VEGF were detected in 35 cases (18.9%), with 17.9% and 20.3% in pTa and pT1 tumors respectively. There was a positive association of VEGF expression with histological grading (p = 0.03). Otherwise, no apparent correlation was observed with remaining biopathological indicators (p > 0.1, respectively). Risk factors in predicting tumor recurrence were multiple tumors at diagnosis and lamina propria invasion (p < 0.05, respectively). Patients with multiple tumors also had a lower survival rate than those with a solitary tumor (p = 0.0008). However, expression of VEGF was not correlated with risk of tumor recurrence or patient survival (p > 0.1).

CONCLUSIONS

Expression of VEGF is one of the characteristics of tumor dedifferentiation and may play a role in the development of a subset of superficial bladder cancer. Evaluation of VEGF expression dose not provide independent prognostic information for patients with superficial bladder cancer.