Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Enhancements in laser-generated hot-electron production via focusing cone targets at short pulse and high contrast

We report on the increase in the accelerated electron number and energy using compound parabolic concentrator (CPC) targets from a short-pulse (∼150 fs), high-intensity (>10^{18} W/cm^{2}), and high-contrast (∼10^{8}) laser-solid interaction. We report on experimental measurements using CPC targets where the hot-electron temperature is enhanced up to ∼9 times when compared to planar targets. The temperature measured from the CPC target is 〈T_{e}〉=4.4±1.3 MeV. Using hydrodynamic and particle in cell simulations, we identify the primary source of this temperature enhancement is the intensity increase caused by the CPC geometry that focuses the laser, reducing the focal spot and therefore increasing the intensity of the laser-solid interaction, which is also consistent with analytic expectations for the geometrical focusing.

The response function of Fujifilm BAS-TR imaging plates to laser-accelerated titanium ions

Calibrated diagnostics for energetic particle detection allow for the systematic study of charged particle sources. The Fujifilm BAS-TR imaging plate (IP) is a reusable phosphorescent detector for radiation applications such as x-ray and particle beam detection. The BAS-TR IP has been absolutely calibrated to many low-Z (low proton number) ions, and extending these calibrations to the mid-Z regime is beneficial for the study of laser-driven ion sources. The Texas Petawatt Laser was used to generate energetic ions from a 100 nm titanium foil, and charge states Ti¹⁰⁺ through Ti¹²⁺, ranging from 6 to 27 MeV, were analyzed for calibration. A plastic detector of CR-39 with evenly placed slots was mounted in front of the IP to count the number of ions that correspond with the IP levels of photo-stimulated luminescence (PSL). A response curve was fitted to the data, yielding a model of the PSL signal vs ion energy. Comparisons to other published response curves are also presented, illustrating the trend of PSL/nucleon decreasing with increasing ion mass.

Crocin, a natural molecule with potentially beneficial effects against skin ageing

OBJECTIVE

Oxidative stress and low-grade chronic inflammation stand out as key features of physiological skin ageing. The aim of this study was to examine in normal human epidermal keratinocytes (NHEK) and human dermal fibroblasts (HDF) grown in vitro, the antioxidant and anti-inflammatory properties of crocin, a carotenoid glycoside responsible for the colour of saffron. Moreover, considering the newly emerging field of skin glycobiology and the presence of two gentiobiosyl moieties in crocin, the effect of crocin on NHEK glycosylation pathways was for the first time investigated.

METHODS

The anti-inflammatory and antioxidant activities of crocin were evaluated by in vitro assays of antioxidation activities, ELISA and microarray analysis. The effect of crocin on keratinocyte glycobiology was evaluated by proprietary GLYcoDiag lectin technologies and microarray analysis.

RESULTS

Crocin is endowed with antioxidant potential against reactive oxygen species, protects squalene against UVA-induced peroxidation and prevents the release of inflammatory mediators. The expression of NF-kB-related genes and glycosylation-related genes is modulated in the presence of crocin.

CONCLUSION

Results could designate this molecule as a promising skin ageing prevention cosmetic agent. Of note, some of these effects could be mediated by protein O-glycosylation and interaction of crocin with osidic receptors of keratinocytes.

Glycan distribution and density in native skin's stratum corneum

Background

The glycosylation of proteins on the surface of corneocytes is believed to play an important role in cellular adhesion in the stratum corneum (SC) of human skin. Mapping with accuracy the localization of glycans on the surface of corneocytes through traditional methods of immunohistochemistry and electron microscopy remains a challenging task as both approaches lack enough resolution or need to be performed in high vacuum conditions.

Materials and methods

We used an advanced mode of atomic force microscope (AFM), with simultaneous topography and recognition imaging to investigate the distribution of glycans on native (no chemical preparation) stripped samples of human SC. The AFM cantilever tips were functionalized with anti‐heparan sulfate antibody and the lectin wheat germ agglutinin (WGA) which binds specifically to N‐acetyl glucosamine and sialic acid.

Results

From the recognition imaging, we observed the presence of the sulfated glycosaminoglycan, heparan sulfate, and the glycans recognized by WGA on the surface of SC corneocytes in their native state. These glycans were found associated with bead‐like domains which represent corneodesmosomes in the SC layers. Glycan density was calculated to be ~1200 molecules/μm² in lower layers of SC compared to an important decrease, (~106 molecules/μm²) closer to the surface due probably to corneodesmosome degradation.

Conclusion

Glycan spatial distribution and degradation is first observed on the surface of SC in native conditions and at high resolution. The method used can be extended to precisely localize the presence of other macromolecules on the surface of skin or other tissues where the maintenance of its native state is required.

Abstract S4-04: Tumor microenvironment of metastasis (TMEM) score is associated with early distant recurrence in hormone receptor (HR) positive, HER2-negative early stage breast cancer (ESBC)

Background: Metastasis is the primary cause of death in ESBC. We have shown in mouse models that a subpopulation of tumor cells expressing invasive Mena isoforms stream, form microanatomic structures (“TMEM”) with endothelial cells and macrophages, intravasate into the circulation at TMEM sites, and metastasize (Harney et al. Cancer Discovery, 2015). Further, TMEM sites (“MetaSites”) are identifiable in human ESBC, and “MetaSite score” [MS] is positively associated with distant recurrence in HR+/HER2- ESBC independent of clinicopathologic features, including IHC4 (Rohan et al. JNCI 2014). Here we determined the association between MS and recurrence in an independent ESBC cohort (E2197; NCT00003519).

Methods: We evaluated primary tumors from 600 patients (median followup 14.8 years) with ESBC (weighted % = 50% T1, 54% N0, 46% N1) treated with surgery and 4 cycles of adjuvant chemotherapy (AC or AT) and endocrine therapy. Grade, ER, PR, and HER2, and Oncotype DX Recurrence Score (RS) were evaluated in central labs (Badve et al. JCO 2008), and MS was determined in a CLIA-certified lab using an analytically validated, fully automated digital pathology/image analysis method that identifies Mena expressing tumor cells in direct contact with CD68+ macrophages and CD31+ endothelial cells (ie, “TMEMs”, or “MetaSites”). The objectives were to determine the association between MS and distant relapse free interval (DRFI) and relapse free interval (RFI). Kaplan-Meier survival curves were used to estimate time-to-event distributions. Cox proportional hazards models were used to assess hazard ratio associated with MS while controlling for covariates, and allowing time-varying association with MS. Both Kaplan-Meier and Cox regression methods addressed stratified sampling by incorporating proper weights. All analyses were performed in R 3.2.3.

Results: MS ranged from 0-199; the weighted mean MS was lower in HR+/HER2- than TN (16.1 vs. 23.8, p=0.001) and HER2+ disease (26.2, p=0.003). MS was not associated with T or N status, and correlated poorly with RS (r=0.29). Proportional hazards models revealed a significant positive association between continuous MS and DRFI (p=0.001) and RFI (p=0.00006) in HR+/HER2- disease in years 0-5 (and by MS tertiles for DRFI [p=0.04] and RFI [p=0.01]), but not after year 5 or in TN or HER2+ disease. Proportional hazards models including clinical covariates (N0 vs. N1; T1 vs. T2; high vs. int. vs. low grade) also revealed significant positive associations for continuous MS with RFI (p=0.04), and borderline association with DRFI (p=0.08). Similar findings for MS (RFI p=0.05;DRFI p=0.10) were noted in a joint model including categorical RS (<18,18-30, >30).

Conclusions: MS, a novel metastasis biomarker reflecting interaction between streaming and metastasizing tumor cells and microenvironment, provides prognostic information complementary to classical clinicopathologic features and RS in HR+/HER2- ESBC. Further evaluation is warranted in order to identify patients at highest risk of recurrence within 5 years most likely to benefit from adjuvant chemotherapy or novel therapies. (Supported by BCRF and NCI CA21115, CA180794, CA23318, CA66636, CA180820).

Citation Format: Sparano JA, Gray R, Oktay MH, Entenberg D, Rohan T, Xue X, Donovan M, Peterson M, Shuber A, Hamilton D, D'Alfonso T, Goldstein LJ, Gerlter F, Davidson N, Condeelis J, Jones J. Tumor microenvironment of metastasis (TMEM) score is associated with early distant recurrence in hormone receptor (HR) positive, HER2-negative early stage breast cancer (ESBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S4-04.

Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV

Laser-plasma accelerators of only a centimetre’s length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.

Laser-plasma accelerators can produce high-energy electron bunches over just a few centimetres of distance, offering possible table-top accelerator capabilities. Wang et al. break the current 1 GeV barrier by applying a petawatt laser to accelerate electrons nearly monoenergetically up to 2 GeV.

Measurement of the plasma astrophysical S factor for the 3He(d,p)4He reaction in exploding molecular clusters

The plasma astrophysical S factor for the 3He(d,p)4He fusion reaction was measured for the first time at temperatures of few keV, using the interaction of intense ultrafast laser pulses with molecular deuterium clusters mixed with 3He atoms. Different proportions of D2 and 3He or CD4 and 3He were mixed in the gas target in order to allow the measurement of the cross section for the 3He(d,p)4He reaction. The yield of 14.7 MeV protons from the 3He(d,p)4He reaction was measured in order to extract the astrophysical S factor at low energies. Our result is in agreement with other S factor parametrizations found in the literature.

Temperature measurements of fusion plasmas produced by Petawatt-Laser-Irradiated D2 - (3)He or CD4 - (3)He clustering gases

Two different methods have been employed to determine the plasma temperature in a laser-cluster fusion experiment on the Texas Petawatt laser. In the first, the temperature was derived from time-of-flight data of deuterium ions ejected from exploding D(2) or CD(4) clusters. In the second, the temperature was measured from the ratio of the rates of two different nuclear fusion reactions occurring in the plasma at the same time: D(d,(3)He)n and (3)He(d,p)(4)He. The temperatures determined by these two methods agree well, which indicates that (i) the ion energy distribution is not significantly distorted when ions travel in the disassembling plasma; (ii) the kinetic energy of deuterium ions, especially the "hottest part" responsible for nuclear fusion, is well described by a near-Maxwellian distribution.

Are neighborhood conditions associated with HIV management?

OBJECTIVES

HIV infection has become a manageable chronic disease as a result of treatment advances. Secondary prevention efforts have proved inadequate to reduce the estimated incidence of new HIV infections. Epidemiological data suggest that geographical clustering of new HIV infections is a common phenomenon, particularly in urban areas among populations of low socioeconomic status. This study aimed to assess the relationship between neighbourhood conditions and HIV management and engagement in high-risk behaviours.

METHODS

During routine out-patient HIV clinic visits, 762 individuals from the St Louis metropolitan area completed behavioural assessments in 2008. Biomedical markers were abstracted from their medical records. Multi-level analyses were conducted based on individuals' census tracts.

RESULTS

The majority of the sample were male and African American. In the adjusted models, individuals residing in neighbourhoods with higher poverty rates were more likely to have lower CD4 cell counts and be current smokers. In neighbourhoods with higher rates of unemployment, individuals were less likely to have a current antiretroviral prescription. In more racially segregated neighbourhoods, individuals reported more depressive symptoms.

CONCLUSIONS

Despite the advances in HIV disease management, neighbourhood characteristics contribute to disparities in HIV care. Interventions that address neighbourhood conditions as barriers to HIV management may provide improved health outcomes.

Optimization of the neutron yield in fusion plasmas produced by Coulomb explosions of deuterium clusters irradiated by a petawatt laser

The kinetic energy of hot (multi-keV) ions from the laser-driven Coulomb explosion of deuterium clusters and the resulting fusion yield in plasmas formed from these exploding clusters has been investigated under a variety of conditions using the Texas Petawatt laser. An optimum laser intensity was found for producing neutrons in these cluster fusion plasmas with corresponding average ion energies of 14 keV. The substantial volume (1-10 mm(3)) of the laser-cluster interaction produced by the petawatt peak power laser pulse led to a fusion yield of 1.6×10(7) neutrons in a single shot with a 120 J, 170 fs laser pulse. Possible effects of prepulses are discussed.

Analysis of differential gene expression in colorectal cancer and stroma using fluorescence-activated cell sorting purification

Tumour stroma gene expression in biopsy specimens may obscure the expression of tumour parenchyma, hampering the predictive power of microarrays. We aimed to assess the utility of fluorescence-activated cell sorting (FACS) for generating cell populations for gene expression analysis and to compare the gene expression of FACS-purified tumour parenchyma to that of whole tumour biopsies. Single cell suspensions were generated from colorectal tumour biopsies and tumour parenchyma was separated using FACS. Fluorescence-activated cell sorting allowed reliable estimation and purification of cell populations, generating parenchymal purity above 90%. RNA from FACS-purified and corresponding whole tumour biopsies was hybridised to Affymetrix oligonucleotide microarrays. Whole tumour and parenchymal samples demonstrated differential gene expression, with 289 genes significantly overexpressed in the whole tumour, many of which were consistent with stromal gene expression (e.g., COL6A3, COL1A2, POSTN, TIMP2). Genes characteristic of colorectal carcinoma were overexpressed in the FACS-purified cells (e.g., HOX2D and RHOB). We found FACS to be a robust method for generating samples for gene expression analysis, allowing simultaneous assessment of parenchymal and stromal compartments. Gross stromal contamination may affect the interpretation of cancer gene expression microarray experiments, with implications for hypotheses generation and the stability of expression signatures used for predicting clinical outcomes.

Identification and Characterization of a Novel Retroviral-Like Aspartic Protease Specifically Expressed in Human Epidermis

Proteases play a pivotal role in epidermal differentiation and desquamation. Separation of a total protein extract from human reconstructed epidermis by two-dimensional gel electrophoresis and subsequent peptide analysis of a specific protein spot identified a new protein exhibiting similarities with the retroviral aspartic protease family. Cloning of the corresponding full-length cDNA revealed an open reading frame encoding for a new protease of 343 amino acids, containing a putative aspartic protease catalytic domain. We named this protein Skin ASpartic Protease (SASPase). RT-PCR and northern blot analysis of various human tissues revealed that SASPase was specifically expressed within the epidermis. Immunohistochemical analysis showed a particularly intense expression restricted to the granular layers, whereas in diseased skin, its expression was changed. Western blot analysis, using a monoclonal antibody, revealed the expression of two forms of the enzyme: a 28 kDa putative proform and the active 14 kDa form. Recombinant truncated SASPase (SASP28) was generated from a prokaryotic expression system in Escherichia coli as a fusion protein with GST. SASP28 degraded insulin and to a lesser extent casein with a pH optimum of 5. As seen for retroviral proteases, an auto-activation processing was evidenced, generating a 14 kDa protein (SASP14). Site-directed mutagenesis inhibited auto-activation of the enzyme. Indinavir, a potent HIV protease inhibitor used in AIDS therapy, had a significant inhibitory effect on rSASPase auto-activation, which could explain its side effects on skin.

Multiple death pathways in retina-derived 661W cells following growth factor deprivation: crosstalk between caspases and calpains

During development of the mammalian retina, neurons that do not succeed in establishing functional synaptic connections are eliminated by apoptosis, allowing the formation of a finely tuned network. Growth factors play a crucial role in controlling the balance between apoptosis and survival signals not only at developmental stages but also in long-term preservation of retinal functions. In the present work, we explore the apoptotic mechanisms triggered by growth factor deprivation of retina-derived 661W cells. Under serum starvation conditions, these cone photoreceptors underwent cell death with participation of caspase-9, -3 and -12. Interestingly, inhibition of caspases did not prevent apoptosis but only resulted in a temporary delay. We show m-calpain activation in parallel with caspases, indicating that more than one execution pathway is available to cone photoreceptors. Moreover, crosstalk of the caspase and calpain pathways was detected, suggesting a loop that may act to amplify the apoptotic cascade.

Caspase-independent photoreceptor apoptosis in vivo and differential expression of apoptotic protease activating factor-1 and caspase-3 during retinal development

Apoptosis is the mode of photoreceptor cell death in many retinal dystrophies. Exposure of Balb/c mice to excessive levels of light induces photoreceptor apoptosis and represents an animal model for the study of retinal degenerations. Caspases have emerged as central regulators of apoptosis, executing this tightly controlled death pathway in many cells. Previously we have reported that light-induced photoreceptor apoptosis occurs independently of one the key executioners of apoptosis, caspase-3. This present study extends these results reporting on the lack of activation of other caspases in this model including caspases-8, -9, -7, and -1. Furthermore, photoreceptor apoptosis cannot be inhibited with the broad range caspase inhibitor zVAD-fmk indicating that light-induced retinal degeneration is caspase-independent. We demonstrate that cytochrome c does not translocate from mitochondria to the cytosol during photoreceptor apoptosis. We also show that during retinal development apoptotic protease activating factor (Apaf-1) protein levels are markedly decreased and this is associated with the inability to activate the mitochondrial caspase cascade in the mature retina. In addition, there is also a significant reduction in expression of caspases-3 and -9 during retinal maturation and these levels do not increase following light exposure. Finally, we show that the calcium-dependent proteases calpains are active during light-induced retinal degeneration and establish that the calcium channel blocker D-cis-diltiazem completely inhibits photoreceptor apoptosis.

Vascular gene discovery using laser capture microdissection of human blood vessels and quantitative PCR

Recent approaches to candidate gene identification and cellular localization have included RNA derived from complex whole tissue profiling on cDNA microarrays followed by in situ hybridization with riboprobes. In this study, the Arcturus PixCell II laser capture microdissection (LCM) system, an argon-based laser-assisted method for the isolation of specific cell types from heterogeneous tissue samples, was used to microdissect the tunica media from normal human arteries and veins (n = 5 in each group). Total RNA was extracted from the sum of 10,000 shots for each blood vessel using the Strataprep MicroKit. RNA was reverse-transcribed, and the resulting cDNA was analyzed using the Applied Biosystems 7700 quantitative PCR system (Q-PCR). Control genes, such as the L-type calcium channel, PECAM (CD-31), and beta-2 microglobulin, were used to assess sample quality and purity. Of 10 laser-captured media samples, five (50%) showed a gene profile that indicated high-quality RNA (abundance of housekeeping genes) and smooth muscle cell enrichment (low levels of PECAM and high levels of the L-type calcium channel). We conclude that the application of the LCM technique to collect smooth muscle cell RNA from the tunica media of human blood vessels can assist in the validation of gene expression and potentially expedite the identification of novel, regulated genes present within vascular smooth muscle.

Light-induced photoreceptor apoptosis in vivo requires neuronal nitric-oxide synthase and guanylate cyclase activity and is caspase-3-independent

Apoptosis is the mode of photoreceptor cell death in inherited and induced retinal degeneration. However, the molecular mechanisms of photoreceptor cell death in human cases and animal models of retinal dystrophies remain undefined. Exposure of Balb/c mice to excessive levels of white light results in photoreceptor apoptosis. This study delineates the molecular events occurring during and subsequent to the induction of retinal degeneration by exposure to white light in Balb/c mice. We demonstrate an early increase in intracellular calcium levels during photoreceptor apoptosis, an event that is accompanied by significant superoxide generation and mitochondrial membrane depolarization. Furthermore, we show that inhibition of neuronal nitric-oxide synthase (nNOS) by 7-nitroindazole is sufficient to prevent retinal degeneration implicating a key role for neuronal nitric oxide (NO) in this model. We demonstrate that inhibition of guanylate cyclase, a downstream effector of NO, also prevents photoreceptor apoptosis demonstrating that guanylate cyclase too plays an essential role in this model. Finally, our results demonstrate that caspase-3, frequently considered to be one of the key executioners of apoptosis, is not activated during retinal degeneration. In summary, the data presented here demonstrate that light-induced photoreceptor apoptosis in vivo is mediated by the activation of nNOS and guanylate cyclase and is caspase-3-independent.

Virulence of a phosphoribosylaminoimidazole carboxylase-deficient Candida albicans strain in an immunosuppressed murine model of systemic candidiasis

The relative pathogenicities of three Candida albicans strains differing in the function of ADE2 (the gene encoding phosphoribosylaminoimidazole carboxylase) were evaluated in a murine candidiasis model. C. albicans strain CAI7 (ade2/ade2), previously constructed by site-specific recombination, was avirulent in immunosuppressed mice compared to the parent strain, CAF2-1, and a heterozygous ADE2/ade2 strain obtained by transforming CAI7 with a wild-type allele. The reduced virulence of CAI7 was correlated with the inability to proliferate in either synthetic medium or serum without the exogenous addition of >10 microg of adenine/ml. The loss of virulence upon site-specific disruption of the ade2 locus, and the restoration of wild-type virulence with the repair of just one ade2 allele, confirmed that the ADE2 gene and de novo purine biosynthesis were required for Candida pathogenicity. The potential of the phosphoribosylaminoimidazole carboxylase enzyme as a novel target for antifungal drug discovery is discussed.

Melastatin expression and prognosis in cutaneous malignant melanoma

PURPOSE

Melastatin (MLSN-1), a novel melanocyte-specific gene recently identified using a genomic approach, is expressed in murine and human melanoma cells at levels inversely proportional to metastatic rates in vivo. We studied the relationship between expression of melastatin mRNA in the primary cutaneous tumor and prognosis in patients with localized malignant melanoma.

PATIENTS AND METHODS

Melastatin mRNA was evaluated by in situ hybridization in primary cutaneous melanoma from 150 patients with localized disease (American Joint Committee on Cancer [AJCC] stage I and II). Multivariate Cox proportional hazards regression analysis was performed to assess the prognostic utility of melastatin mRNA expression while adjusting for other prognostic indicators.

RESULTS

Uniform melastatin mRNA expression in the primary tumor was correlated with prolonged disease-free survival (P < .0001). Multivariate analysis revealed that melastatin status, mitotic rate, and tumor thickness influence disease-free survival independently. The 8-year disease-free survival rate in AJCC stage I patients whose tumors diffusely expressed melastatin mRNA was 100%, whereas in stage I patients with melastatin loss, the disease-free survival rate was 77% +/- 15% (median +/- SE). In patients with stage II disease whose tumors diffusely expressed melastatin mRNA, the 8-year disease-free survival rate was 90% +/- 7%, whereas in patients with melastatin loss, the disease-free survival rate was 51% +/- 8%.

CONCLUSION

Downregulation of melastatin mRNA in the primary cutaneous tumor is a prognostic marker for metastasis in patients with localized malignant melanoma and is independent of tumor thickness and other variables. Used in combination, melastatin status and tumor thickness allow for the identification of subgroups of patients at high and low risk of developing metastatic disease.

Trends in admissions to a regional secure unit (1983-1997)

Admissions and discharges from a 30-bed regional secure unit (RSU) were surveyed over a 15-year period. In the last five years there has been a significant increase in the average length of stay of patients and a marked decrease in the number of admissions and discharges. The reasons for this 'silting up' of the RSU by longer-term patients and the consequences for an effective forensic psychiatric service are discussed.

A novel angiotensin-converting enzyme-related carboxypeptidase (ACE2) converts angiotensin I to angiotensin 1-9

ACE2, the first known human homologue of angiotensin-converting enzyme (ACE), was identified from 5' sequencing of a human heart failure ventricle cDNA library. ACE2 has an apparent signal peptide, a single metalloprotease active site, and a transmembrane domain. The metalloprotease catalytic domains of ACE2 and ACE are 42% identical, and comparison of the genomic structures indicates that the two genes arose through duplication. In contrast to the more ubiquitous ACE, ACE2 transcripts are found only in heart, kidney, and testis of 23 human tissues examined. Immunohistochemistry shows ACE2 protein predominantly in the endothelium of coronary and intrarenal vessels and in renal tubular epithelium. Active ACE2 enzyme is secreted from transfected cells by cleavage N-terminal to the transmembrane domain. Recombinant ACE2 hydrolyzes the carboxy terminal leucine from angiotensin I to generate angiotensin 1-9, which is converted to smaller angiotensin peptides by ACE in vitro and by cardiomyocytes in culture. ACE2 can also cleave des-Arg bradykinin and neurotensin but not bradykinin or 15 other vasoactive and hormonal peptides tested. ACE2 is not inhibited by lisinopril or captopril. The organ- and cell-specific expression of ACE2 and its unique cleavage of key vasoactive peptides suggest an essential role for ACE2 in the local renin-angiotensin system of the heart and kidney. The full text of this article is available at http://www. circresaha.org.

Apoptotic photoreceptor death in the rhodopsin knockout mouse in the presence and absence of c-fos

A combined total of approximately 100 mutations have been encountered within the rhodopsin gene in retinitis pigmentosa (RP) and congenital night blindness. Mice carrying a targeted disruption of the rhodopsin gene phenotypically mimic RP, losing their photoreceptors over a period of 3 months and having no recordable rod electroretinogram. These animals will serve as a model for both recessive and dominant disease (in the latter case, the presence of normal and mutant human rod opsin transgenes on the murine Rho(-/-)background). Precise knowledge of apoptotic photoreceptor cell death, together with factors which may influence apoptosis will be required for optimum utility of Rho(-/-)mice as a model for therapeutic genetic intervention. A peak phase of apoptosis of the photoreceptors of Rho(-/-)mice was shown to occur at 24 days post-birth. The extent of apoptosis appeared to be similar, irrespective of whether or not the rod opsin knockout was present on a c-fos(+/+)or c-fos(-/-)genetic background, the latter known to favor survival of photoreceptors following exposure of mouse retinas to excessive light. These data clearly support the existence in animals of distinct apoptotic pathways in light-induced, as opposed to mutation-induced apoptosis, and together with similar observations recently reported in studies of the naturally occurring rd mouse, may assist in focusing future research on precisely defining the distinct molecular pathways giving rise to such dichotomy.

Density-dependent growth inhibition of fibroblasts ectopically expressing p27(kip1)

The cyclin/cyclin-dependent kinase (cdk) inhibitor p27(kip1) is thought to be responsible for the onset and maintenance of the quiescent state. It is possible, however, that cells respond differently to p27(kip1) in different conditions, and using a BALB/c-3T3 cell line (termed p27-47) that inducibly expresses high levels of this protein, we show that the effect of p27(kip1) on cell cycle traverse is determined by cell density. We found that ectopic expression of p27(kip1) blocked the proliferation of p27-47 cells at high density but had little effect on the growth of cells at low density whether exponentially cycling or stimulated from quiescence. Regardless of cell density, the activities of cdk4 and cdk2 were markedly repressed by p27(kip1) expression, as was the cdk4-dependent dissociation of E2F4/p130 complexes. Infection of cells with SV40, a DNA tumor virus known to abrogate formation of p130- and Rb-containing complexes, allowed dense cultures to proliferate in the presence of supraphysiological amounts of p27(kip1) but did not stimulate cell cycle traverse when cultures were cotreated with the potent cdk2 inhibitor roscovitine. Our data suggest that residual levels of cyclin/cdk activity persist in p27(kip1)-expressing p27-47 cells and are sufficient for the growth of low-density cells and of high-density cells infected with SV40, and that effective disruption of p130 and/or Rb complexes is obligatory for the proliferation of high-density cultures.

Prevention of rejection in cardiac transplantation by blockade of the interleukin-2 receptor with a monoclonal antibody

BACKGROUND

Alloantigen-activated T cells express the high-affinity interleukin-2 receptor. Specific blockade of this receptor with the human IgG1 monoclonal antibody daclizumab may prevent rejection of allografts after cardiac transplantation without inducing global immunosuppression.

METHODS

We randomly assigned 55 nonsensitized patients undergoing a first cardiac transplantation to receive either induction therapy with daclizumab (1.0 mg per kilogram of body weight), given intravenously within 24 hours after cardiac-transplantation surgery and every two weeks thereafter, for a total of five doses, or generalized immunosuppressive therapy. Concomitant immunosuppression was achieved in both groups with cyclosporine, mycophenolate mofetil, and prednisone. The primary end points were the incidence and severity of acute rejection, and the length of time to a first episode of biopsy-confirmed rejection.

RESULTS

Of the 55 patients in the study, 28 were randomly assigned to receive daclizumab and 27 served as the control group. During induction therapy, the mean frequency of acute rejection episodes (defined as a histologic grade of 2 or higher according to the classification of the International Society of Heart and Lung Transplants) was 0.64 per patient in the control group and 0.19 per patient in the daclizumab group (P=0.02). Acute rejection developed in 17 of 27 patients in the control group (63 percent), as compared with 5 of 28 patients in the daclizumab group (18 percent; relative risk, 2.8; 95 percent confidence interval, 1.1 to 7.4; P=0.04). Throughout follow-up, there were nine patients with episodes of acute rejection of histologic grade 3 in the control group, as compared with two in the daclizumab group (P= 0.03), and the time to a first episode of rejection was significantly longer in the daclizumab group (P=0.04). There were no adverse reactions to daclizumab and no significant differences between the groups in the incidence of infection or cancer during follow-up.

CONCLUSIONS

Induction therapy with daclizumab safely reduces the frequency and severity of cardiac-allograft rejection during the induction period.

In vitro modulation of macrophage phenotype and inhibition of polymer degradation by dexamethasone in a human macrophage/Fe/stress system

A new in vitro accelerated biological model, the macrophage-FeCl2-stress system was used for the evaluation of dexamethasone (DEX)-polymer formulations. This model combines the effects of cells (macrophages), transition metal ions (Fe2+), and polymer stress to promote material biodegradation. The cell and material effects of DEX, either in solution or incorporated into a polyetherurethane matrix (DEX/PEU), were monitored. Cell morphology and hydroperoxide formation in the polymer during cell culturing were characterized. After a subsequent treatment with FeCl2 the development of environmental stress cracking in the polymer was evaluated. We attempted to duplicate the biodegradation of PEU in terms of environmental stress cracking (ESC). Our results support the direct involvement of macrophages in polyetherurethane oxidation, probably by inducing hydroperoxide formation in the polymer structure. Under the influence of stress or strain, polymers with sufficient hydroperoxides degrade in the presence of Fe2+ metal ions in a manner that closely resembles the stress cracking that is observed in vivo. By contrast, polymers treated with either agents that inhibit cell activation and/or the oxidative burst, or with cells with no oxidative burst did not show signs of the biodegradative process. We demonstrated a reduction in hydroperoxide formation and no later ESC development in macrophage-cultured PEU in the presence of DEX in solution or in DEX-loaded PEU. We believe the prevention of initial polymer oxidation by reducing the cell's potential to produce oxidative stress at the tissue-biomaterial interface can directly inhibit the ESC degradation of chronically implanted polymers. The in vitro macrophage-Fe-stress system is a valuable tool for reliable assessment and cost-effective evaluation of biomaterials.

Retinoid binding proteins-expression patterns in the human placenta

The present study examined the expression and occurrence of different retinoid binding proteins in human first trimester and term placenta. At both stages, messenger RNA for the serum transport vehicle for retinol, retinol-binding protein (RBP), was detected only in decidual cells of the basal plate. In contrast, immunoreactive RBP (irRBP) was present in syncytiotrophoblast, core mesenchyme and lumen of vessels in placental villi and in mesenchyme and decidual cells of the basal plate. In villi of term placentae, however, staining for irRBP was lost in syncytiotrophoblasts and villous core mesenchyme. A putative placental RBP-receptor, approx 60-65kDa, was detected in the villous syncytiotrophoblast of both stages investigated. Immunoreactivity for the cellular retinol binding protein type I (CRBP I), was found in villous stromal cells and in decidual cells of the basal plate in sections of first trimester and term placenta. These results may suggest that maternal RBP-retinol is transferred across the chorionic villi to the fetal/villous circulation and that villous absorption of the complex is mediated via a placental RBP-receptor. Moreover, binding and possibly also metabolism of retinol may occur in the CRBP I positive villous stromal cells and decidual cells of the basal plate. In the latter, release of placental RBP-retinol may also be anticipated.

Coordinate action of Wt1 and a modifier gene supports embryonic survival in the oviduct

The Wt1 gene, originally identified as a tumor suppressor gene associated with Wilms' tumors, encodes a zinc finger containing transcription factor expressed during gonadal and kidney development. Although Wt1 appears to be required for gonadal and kidney development, no reproductive defects were observed in outbred females heterozygous for a targeted mutation in Wt1. In contrast, no litters were obtained from Wt1 +/- females on a strain 129/Sv inbred genetic background. Ovaries were smaller in Wt1 +/- 129/Sv mice and produced fewer ova, but transplanted Wt1 +/- ovaries from 129/Sv females were able to support successful pregnancies. The inability of Wt1 +/- 129/Sv females to produce successful implantations after ovulation and fertilization appeared to be due to the failure of one-cell embryos to undergo mitosis, such that they were lost in the oviduct before reaching the uterus. Approximately 50% of Wt1 +/- females generated from a backcross of Wt1 +/- 129/Sv:C57BI/6 F1 hybrids to 129/Sv were fertile, indicating the presence of a Wt1 modifier gene that affects survival of the preimplantation embryo. Neither levels of WT1 protein nor the ratio of WT1 spice forms were significantly altered in Wt1 +/- reproductive organs, suggesting that this modifier effect acts downstream of WT1. Wt1 is therefore among a small subset of genes required for survival of the pre-implantation embryo, and appears to function non-autonomously.