In vivo optogenetics using a Utah Optrode Array with enhanced light output and spatial selectivity

Optogenetics allows manipulation of neural circuits in vivo with high spatial and temporal precision. However, combining this precision with control over a significant portion of the brain is technologically challenging (especially in larger animal models). Here, we have developed, optimised, and tested in vivo, the Utah Optrode Array (UOA), an electrically addressable array of optical needles and interstitial sites illuminated by 181 µLEDs and used to optogenetically stimulate the brain. The device is specifically designed for non-human primate studies. Thinning the combined µLED and needle backplane of the device from 300 µm to 230 µm improved the efficiency of light delivery to tissue by 80%, allowing lower µLED drive currents, which improved power management and thermal performance. The spatial selectivity of each site was also improved by integrating an optical interposer to reduce stray light emission. These improvements were achieved using an innovative fabrication method to create an anodically bonded glass/silicon substrate with through-silicon vias etched, forming an optical interposer. Optical modelling was used to demonstrate that the tip structure of the device had a major influence on the illumination pattern. The thermal performance was evaluated through a combination of modelling and experiment, in order to ensure that cortical tissue temperatures did not rise by more than 1°C. The device was tested in vivo in the visual cortex of macaque expressing ChR2-tdTomato in cortical neurons. It was shown that the strongest optogenetic response occurred in the region surrounding the needle tips, and that the extent of the optogenetic response matched the predicted illumination profile based on optical modelling - demonstrating the improved spatial selectivity resulting from the optical interposer approach. Furthermore, different needle illumination sites generated different patterns of low-frequency potential (LFP) activity.

An optrode array for spatiotemporally-precise large-scale optogenetic stimulation of deep cortical layers in non-human primates

Optogenetics has transformed studies of neural circuit function, but remains challenging to apply to non-human primates (NHPs). A major challenge is delivering intense, spatiotemporally-precise, patterned photostimulation across large volumes in deep tissue. Such stimulation is critical, for example, to modulate selectively deep-layer corticocortical feedback circuits. To address this need, we have developed the Utah Optrode Array (UOA), a 10×10 glass needle waveguide array fabricated atop a novel opaque optical interposer, and bonded to an electrically addressable µLED array. In vivo experiments with the UOA demonstrated large-scale, spatiotemporally precise, activation of deep circuits in NHP cortex. Specifically, the UOA permitted both focal (confined to single layers/columns), and widespread (multiple layers/columns) optogenetic activation of deep layer neurons, as assessed with multi-channel laminar electrode arrays, simply by varying the number of activated µLEDs and/or the irradiance. Thus, the UOA represents a powerful optoelectronic device for targeted manipulation of deep-layer circuits in NHP models.

An Open Resource for Non-human Primate Optogenetics

Optogenetics has revolutionized neuroscience in small laboratory animals, but its effect on animal models more closely related to humans, such as non-human primates (NHPs), has been mixed. To make evidence-based decisions in primate optogenetics, the scientific community would benefit from a centralized database listing all attempts, successful and unsuccessful, of using optogenetics in the primate brain. We contacted members of the community to ask for their contributions to an open science initiative. As of this writing, 45 laboratories around the world contributed more than 1,000 injection experiments, including precise details regarding their methods and outcomes. Of those entries, more than half had not been published. The resource is free for everyone to consult and contribute to on the Open Science Framework website. Here we review some of the insights from this initial release of the database and discuss methodological considerations to improve the success of optogenetic experiments in NHPs.

Distinct Laminar Processing of Local and Global Context in Primate Primary Visual Cortex

Visual perception is affected by spatial context. In visual cortex, neuronal responses to stimuli inside the receptive field (RF) are suppressed by stimuli in the RF surround. To understand the circuits and cortical layers processing spatial context, we simultaneously recorded across all layers of macaque primary visual cortex while presenting stimuli at increasing distances from the recorded cells' RF. We find that near versus far-surround stimuli activate distinct layers, thus revealing unique laminar contributions to the processing of local and global spatial context. Stimuli in the near-surround evoke the earliest subthreshold responses in superficial and upper-deep layers, and earliest suppression of spiking responses in superficial layers. Conversely, far-surround stimuli evoke the earliest subthreshold responses in feedback-recipient layer 1 and lower-deep layers, and earliest suppression of spiking responses almost simultaneously in all layers, except 4C, where suppression emerges last. Our results suggest distinct circuits for local and global signal integration.

Abstract P1-01-20: Adjuvant statin therapy efficacy is dictated by tumor dormancy and statin lipophilicity in ex vivo and in vivo models of metastatic breast cancer

Metastasis in breast cancer patients heralds mortality, as disseminated disease is generally chemoresistant. After tumor cells reach the ectopic tissue, they undergo an epithelial reversion to enter a period of quiescence, termed dormancy, which may last for decades before outgrowing again as mesenchymal/dedifferentiated masses. Thus, long-term, relatively non-toxic interventions that prevent metastatic outgrowth are needed to treat this mortal stage of tumor progression.

Epidemiological analyses have suggested that statin usage, for cardiovascular indications, is correlated with a reduction in clinically-evident metastatic (though not in incidence of primary) breast cancer. The goal of this study is to demonstrate this is due to statins suppressing breast cancer cell proliferation and keeping the micrometastases in the dormant state.

We have found that atorvastatin and simvastatin limit the growth of some cancer cell lines, but not others. The sensitive lines were marked by lacking surface E-cadherin, the hallmark of the mesenchymal phenotype. When E-cadherin is downregulated on epithelial tumor cells, the cells become growth inhibited by the statins. Furthermore, this is a direct effect, as we now have shown that hydrophilic statins are relatively ineffective compared to the membrane permeant lipophilic statins as tumor cells generally lack the transporters that enable these drugs to gain access to the cells.

To determine whether the statins target the emergent metastatic tumor cells, we are using an all human microphysiological system (MPS) of the most common site for metastases, the liver. Briefly, a micro-hepatic tissue is established by seeding primary human liver cells in a porous scaffold subject to a physiological flow. RFP-labeled breast cancer cells are seeded into these microtissues and examined weeks later. Liver function and health are monitored by clinical chemistry assays performed on supernatant samples. We have previously shown that this system robustly reproduces tumor dormancy. Initial studies suggest that statins suppress the emergence of dormant tumor cells when challenged by stressors that lead to outgrowth. Additionally, atorvastatin suppresses proliferation of mesenchymal but not epithelial breast cancer cells in intrasplenic and mammary fat pad injection models for breast cancer metastasis to the liver and lung respectively. As 26% of adults currently take a statin for other medical conditions, these studies may suggest the best statin to use in the context of maintaining breast cancer dormancy long-term and delaying or avoiding the morbid emergence.

Citation Format: Beckwitt CH, Clark AM, Warita K, Oltvai ZN, Wells A. Adjuvant statin therapy efficacy is dictated by tumor dormancy and statin lipophilicity in ex vivo and in vivo models of metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-20.

A Pathway to Personalizing Therapy for Metastases Using Liver-on-a-Chip Platforms

Metastasis accounts for most cancer-related deaths. The majority of solid cancers, including those of the breast, colorectum, prostate and skin, metastasize at significant levels to the liver due to its hemodynamic as well as tumor permissive microenvironmental properties. As this occurs prior to detection and treatment of the primary tumor, we need to target liver metastases to improve patients' outcomes. Animal models, while proven to be useful in mechanistic studies, do not represent the heterogeneity of human population especially in drug metabolism lack proper human cell-cell interactions, and this gap between animals and humans results in costly and inefficient drug discovery. This underscores the need to accurately model the human liver for disease studies and drug development. Further, the occurrence of liver metastases is influenced by the primary tumor type, sex and race; thus, modeling these specific settings will facilitate the development of personalized/targeted medicine for each specific group. We have adapted such all-human 3D ex vivo hepatic microphysiological system (MPS) (a.k.a. liver-on-a-chip) to investigate human micrometastases. This review focuses on the sources of liver resident cells, especially the iPS cell-derived hepatocytes, and examines some of the advantages and disadvantages of these sources. In addition, this review also examines other potential challenges and limitations in modeling human liver.

A liver microphysiological system of tumor cell dormancy and inflammatory responsiveness is affected by scaffold properties

Distant metastasis is the major cause of breast cancer-related mortality, commonly emerging clinically after 5 or more years of seeming 'cure' of the primary tumor, indicating a quiescent dormancy. The lack of relevant accessible model systems for metastasis that recreate this latent stage has hindered our understanding of the molecular basis and the development of therapies against these lethal outgrowths. We previously reported on the development of an all-human 3D ex vivo hepatic microphysiological system that reproduces several features of liver physiology and enables spontaneous dormancy in a subpopulation of breast cancer cells. However, we observed that the dormant cells were localized primarily within the 3D tissue, while the proliferative cells were in contact with the polystyrene scaffold. As matrix stiffness is known to drive inflammatory and malignant behaviors, we explored the occurrence of spontaneous tumor dormancy and inflammatory phenotype. The microphysiological system was retrofitted with PEGDa-SynKRGD hydrogel scaffolding, which is softer and differs in the interface with the tissue. The microphysiological system incorporated donor-matched primary human hepatocytes and non-parenchymal cells (NPCs), with MDA-MB-231 breast cancer cells. Hepatic tissue in hydrogel scaffolds secreted lower levels of pro-inflammatory analytes, and was more responsive to inflammatory stimuli. The proportion of tumor cells entering dormancy was markedly increased in the hydrogel-supported tissue compared to polystyrene. Interestingly, an unexpected differential response of dormant cells to varying chemotherapeutic doses was identified, which if reflective of patient pathophysiology, has important implications for patient dosing regimens. These findings highlight the metastatic microphysiological system fitted with hydrogel scaffolds as a critical tool in the assessment and development of therapeutic strategies to target dormant metastatic breast cancer.

Abstract P2-05-19: Breast cancer dormancy, re-emergence, and treatment

Breast cancer (BrCa) mortality continues to result predominately from distant metastases that can emerge years after successful treatment of the primary disease. Metastatic resistance to agents that eradicate the primary mass is likely due to protection from the metastatic microenvironment and the quiescent state of dormant BrCa cells. Advancements for the treatment of metastatic tumors have been made, but significant progress has been hampered by the lack of relevant model systems, particularly for dormancy. We address this gap with an innovative all-human 3D liver microphysiological system (MPS). The liver is both a major site for BrCa metastasis (and other solid tumors) and the primary site of drug metabolism and limiting toxicities, an important consideration in evaluating cancer therapy efficacy and availability.

Primary hepatocytes and non-parenchymal cells (NPC) from human liver resections were seeded into the MPS. Following tissue formation on day 3, tagged BrCa cells were seeded and allowed a minimum of 4 days to integrate into the tissue before interventions were initiated. On day 7, chemotherapy treatment of micrometastases was initiated for 72h. Cultures were allowed 3 days to recover before the MPS was challenged with inflammatory factors (LPS/EGF) for 48h. BrCa cells were then re-treated with chemotherapy (either the same or alternate therapy) on day 21 for 72h. Hepatocyte function and injury were measured by urea, AST, ALT, A1AT, fibrinogen and CYP P450 assays. BC proliferation was monitored by quantification, Ki67 staining, and EdU incorporation. Communication networks within the metastatic microenvironment during different stages of metastatic BrCa progression were identified using Luminex assays (55 analytes).

The metastatically aggressive MDA-MB-231 BrCa cells demonstrated growth attenuation after 12d of culture in a subpopulation of cells (Ki67-/EdU-). Treatment of BrCa cells with doxorubicin for 72h eradicates the cycling cells, leaving behind a dormant cell population (Ki67-/EdU-) that can be subsequently stimulated to cycle by addition of inflammatory stimuli. A second dose of doxorubicin or cisplatin reduced the BrCa load but did not eradicate the BrCa. Luminex analysis of culture supernatants identified signaling molecules potentially involved in metastatic progression. In addition, we present the use of adjuvant therapy in the MPS to prevent this outgrowth of the dormant tumor cells.

In parallel, we have piloted hydrogel scaffolds that better support tissue formation and produce signals consistent with a healthier liver physiology. Hydrogels enhanced MDA-MB-231 cell entry into dormancy, resulting in reduced efficacy of doxorubicin treatment with greater persistence of tumor load.

The MPS provides a mechanism to close the gap in understanding metastatic dormancy. We demonstrate spontaneous dormancy for the first time in an all-human system and mimicked the dormancy and outgrowth observed in patients. Namely, that dormant BrCa are resistant to chemotherapy and can be stimulated to reemerge following an inflammatory insult. The completion of these studies will provide insights into the tumor biology of metastatic seeding, dormancy, and re-emergence and provide an accessible tool for testing therapeutics against metastatic BrCa in a metabolically competent system capable of evaluating dose-limiting toxicity.

Citation Format: Beckwitt C, Wheeler SE, Clark AM, Pillai VC, Young CL, Stolz DB, Lauffenburger DA, Venkataramanan R, Griffith LG, Wells A. Breast cancer dormancy, re-emergence, and treatment. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-05-19.

How to research the mechanisms of non-pharmacological cardiac interventions

OBJECTIVE

To discuss research into the mechanisms of non-pharmacological interventions for cardiac populations.

METHODS

Overview of past research and theory.

RESULTS

Non-pharmacological interventions for cardiac patients (including: cardiac rehabilitation, heart failure disease management programs and psychosocial interventions) have never been so common or diverse, but also have never been subject to so much scrutiny and skepticism. Better understanding of outcomes of these interventions is an urgent global priority. Mechanisms are the "underlying entities, processes, or structures which operate in particular contexts to generate outcomes of interest."

PRACTICE

Research into the mechanisms of non-pharmacological interventions offers useful and robust knowledge of how and why cardiac interventions work that can be vital to explaining outcomes from interventions and inconsistencies in results.

CONCLUSIONS

Research into intervention mechanisms can inform the design and optimization of interventions.

IMPLICATIONS

We recommend that future research into the mechanisms of non-pharmacological interventions for cardiac population 1) view effectiveness as 'somewhat' patterned, 2) conceptualize mechanisms adequately, 3) assume they are hidden, 4) examine how context affects mechanisms, and 6) address what works for whom, when, and why.

Spontaneous dormancy of metastatic breast cancer cells in an all human liver microphysiologic system

Background:

Metastatic outgrowth in breast cancer can occur years after a seeming cure. Existing model systems of dormancy are limited as they do not recapitulate human metastatic dormancy without exogenous manipulations and are unable to query early events of micrometastases.

Methods:

Here, we describe a human ex vivo hepatic microphysiologic system. The system is established with fresh human hepatocytes and non-parenchymal cells (NPCs) creating a microenvironment into which breast cancer cells (MCF7 and MDA-MB-231) are added.

Results:

The hepatic tissue maintains function through 15 days as verified by liver-specific protein production and drug metabolism assays. The NPCs form an integral part of the hepatic niche, demonstrated within the system through their participation in differential signalling cascades and cancer cell outcomes. Breast cancer cells intercalate into the hepatic niche without interfering with hepatocyte function. Examination of cancer cells demonstrated that a significant subset enter a quiescent state of dormancy as shown by lack of cell cycling (EdU⁻ or Ki67⁻). The presence of NPCs altered the cancer cell fraction entering quiescence, and lead to differential cytokine profiles in the microenvironment effluent.

Conclusions:

These findings establish the liver microphysiologic system as a relevant model for the study of breast cancer metastases and entry into dormancy.

Abstract P5-04-08: Modeling breast cancer dormancy

Most cancer mortality results from distant metastases. The metastatic microenvironment protects ectopic tumors, these nodules are often resistant to agents that eradicate the primary mass. Although significant interventional progress has been made on primary tumors, the lack of relevant accessible model in vitro systems in which to study metastases has plagued metastatic therapeutic development – particularly among micrometastases. One third of women diagnosed with breast cancer (BC) will have metastatic disease which often presents years after a seeming cure from the primary malignancy. An in silico model of micrometastases strongly suggests that these disseminated cells are quiescent, or ‘dormant’, for long periods of time. Current models fail to recapitulate metastatic dormancy, in vivo due to issues of spontaneous metastases and rodent lifespan and in vitro due to the nascent state of organotypic organs or microphysiological systems (MPS). We hypothesize that even the most developed MPS do not allow tumors to attain dormancy due to continued stress signaling from stiff matrices and an artificial microenvironment. We use an innovative all human three dimensional liver MPS to faithfully reproduce human physiology and pathology. In the initial iteration, the liver cells are isolated from therapeutic partial hepatectomies, but as this source may be limiting, we are examining induced pluripotent stem cells (iPSC). Currently these iPSC-derived hepatocyte-like cells demonstrate cyp p450 activity and production of fibrinogen and urea through 15 days in our MPS, albeit at levels below fresh human hepatocytes; optimization protocols are underway.

In the first phase of this work we optimized the flow rate and seeding of hepatocytes with non-parenchymal cells (NPCs) from fresh human liver resections. We found that higher flow rates produced poorer tissue formation and increased stress fibers/actin filaments. We maintained functioning hepatocytes in the MPS through 15 days. Hepatocyte function and injury was measured by urea, lactate, AST, ALT, A1AT, fibrinogen and cyp p450 assays. NPCs survived through the 15 day endpoint with immunofluorescent microscopy visualizing leukocytes, endothelial cells and macrophages. The proliferative MDA MB 231 BC cell line showed preliminary evidence of growth attenuation after 12 days of culture in a subpopulation of cells in our MPS. Luminex cancer panel studies are underway with systems biology modeling to describe a communication network in the early microenvironment of micrometastases.

In parallel we are piloting hydrogel scaffolds that support tissue formation but provide a more physiologic rheology; stiff supporting materials yield an inflammatory phenotype in the NPC which forces even well-differentiated BC cells towards a mesenchymal phenotype. We found that hydrogels support hepatocytes through 15 days and incorporate cancer cells. Micropumps are also being developed by Draper Laboratories to allow for physiologic diurnal variations of hormones and nutrients to liver tissues to accurately assess dormancy and chemotherapy response. The completion of these studies will provide insights into the tumor biology of dormant micrometastases and an accessible tool for testing of therapeutics against metastatic BC in a metabolically competent system.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-04-08.

Metabolism and distribution of primaquine in monkeys

Rhesus monkeys were administered primaquine diphosphate (6.0 to 10.5 mg/kg, I.V.), and plasma samples were analyzed by high performance liquid chromatography for the presence of the unchanged drug and the major metabolite , 8-(3-carboxy-l-methylpropylamino)-6-methoxyquinoline (II). Primaquine had an unusually high affinity for tissue compartments which produced a rapid initial drop in plasma concentration. Within 15 minutes, the plasma concentration of II far exceeded that of primaquine. 35 to 83 % of the primaquine dose was converted to II; moreover, metabolite II possessed much lower affinity for the tissue compartments than primaquine itself.

Reward processing: a global brain phenomenon?

Rewards and punishments (reinforcement) powerfully shape behavior. Accordingly, their neuronal representation is of significant interest, both for understanding normal brain-behavior relationships and the pathophysiology of disorders such as depression and addiction. A recent article by Vickery and colleagues (Neuron 72: 166-177, 2011) provides evidence that the neural response to rewards and punishments is surprisingly widespread, suggesting the need for examination of the specific roles of areas not commonly included in the canonical reward circuitry in processing reinforcement.

Cardiac rehabilitation: into the future

Cardiac rehabilitation is increasingly recognised as an integral component of comprehensive cardiac care. The evidence supporting its effectiveness in reducing morbidity and mortality and improving quality of life is compelling. Yet, despite this recognition and exhortations that its implementation should be a key priority, most cardiac patients do not receive rehabilitation. Service provision varies markedly and many programmes are focused on select populations, often operate in an inflexible manner and fail to add potential value. Issues of suboptimal referral, enrolment and completion are poorly addressed and the potential for embracing novel methods and the latest technology are rarely exploited. This paper reviews the current status of cardiac rehabilitation and proposes ways to improve access and uptake and reduce inequity to ensure that those who are likely to benefit from this complex intervention do so.

Cryopreservation-induced human sperm DNA damage is predominantly mediated by oxidative stress rather than apoptosis

BACKGROUND

Whereas studies have revealed that the cryopreservation of human semen increases sperm DNA fragmentation, the mechanisms involved in this type of cryo-injury are largely unknown. Elucidation of these mechanisms may provide insight into preventing such injury.

METHODS

We obtained 60 semen samples from 60 men and conducted experiments to determine the cause of cryopreservation-induced DNA fragmentation using 8-oxo-7,8-dihydro-2'deoxyguanosine (8OHdG) as a biomarker of oxidative stress, percentage caspase positive cells as an indicator of apoptosis, the potential antioxidant genistein and the caspase inhibitor Z-VAD(OMe)-FMK.

RESULTS

Cryopreservation led to a significant increase in percentage DNA fragmentation, percentage 8OHdG and percentage caspase positive cells (P < 0.001). Percentage DNA fragmentation was positively correlated with percentage 8OHdG before (r = 0.756, P < 0.001) and after cryopreservation (r = 0.528, P = 0.017). The addition of 50 and 100 microM genistein to the cryoprotectant had a significant protective effect on sperm DNA (P < 0.001) although the caspase inhibitor demonstrated no difference to the control.

CONCLUSIONS

Human sperm DNA fragmentation is associated with an increase in oxidative stress during cryopreservation, rather than the activation of caspases and apoptosis. The estrogenic compound genistein may be useful in reducing this effect but larger trials are needed to confirm this.

Genomic and genetic approaches for the identification of antifungal drug targets

Understanding how novel antifungal compounds work in target cells is useful not only in facilitating the discovery of new drugs but also new tools that can be used for further exploration of the targeted biological pathways and their regulation. Various genomic and genetic technologies have been developed in the model yeast Saccharomyces cerevisiae, and have been successfully used to identify drug target pathways. This review discusses the methods developed for some of these technologies, and how they have been used to evaluate the cellular pathways affected by a variety of therapeutic drugs and inhibitors. The advantages and disadvantages of each method are considered, and new advances are highlighted where applicable. The investigation of the mechanism of action of new antifungal compounds will undoubtedly lead to the development of new antifungal therapies targeting new fungal pathways that are more specific and less toxic than currently available antifungal drugs.

Results of a postal survey of scrapie in the Shetland Islands in 2003

In February 2003, a postal survey of 1279 sheep farmers in the Shetland Islands yielded 586 responses (46 per cent response rate). The principal aim of the survey was to gather information on the history and control of scrapie. Overall, 28.5 per cent of the respondents thought they had had a case of scrapie in their flock at some time. There was a slow increase in the proportion of affected flocks during the 1970s, followed by a more rapid increase during the 1980s and early 1990s, and a decline from the mid-1990s onwards. The peak proportion of affected flocks was approximately 6 per cent in 1994. Of the farmers who had ever had scrapie in their flock, 97.1 per cent had attempted to control the disease. The most common method of control was breeding from non-susceptible tups, used by 90.6 per cent of the affected flocks and 75.1 per cent of the flocks that had never been affected. A comparison of the characteristics of the affected and unaffected flocks indicated that an increased risk of scrapie was associated with the larger flocks, the open flocks and the flocks that bought in lambs. The basic reproduction ratio for the spread of scrapie between flocks was estimated to be 1.47, and the mean duration of an outbreak within a flock was estimated to be approximately two years.

The Shetland Islands scrapie monitoring and control programme: Analysis of the clinical data collected from 772 scrapie suspects 1985–1997

There were 574 scrapie positive suspects (histopathological scrapie lesions present) and 198 scrapie negative suspects (histopathological scrapie lesions absent). The greatest number of scrapie cases were recorded in sheep of 2, 3 and 4 years of age which represented 17%, 36% and 23% of the scrapie positive suspects, respectively. The sign sensitivities and specificities for the ten recorded signs were, respectively: pruritus (62%, 42%), ataxia (23%, 74%), hyperaesthesia (32%, 74%), wool loss (25%, 73%), fleece discolouration (29%, 85%), bruxism (23%, 69%), nibbling reflex (17%, 58%), head rubbing (47%, 78%), poll rubbing (25%, 83%). These single signs had poor discriminatory values with likelihood ratios close to one (range 0.89-1.21); combinations of the four signs, pruritus, wool loss, ataxia, hyperaesthesia and emaciation were more discriminatory (range 0.30-4.3). This study covered a time period when bovine spongiform encephalopathy (BSE) might have been introduced into the sheep population on the Shetland Islands via contaminated feed. No temporal changes could be detected in the age structure of the affected animals.

Improving evidence based cardiac care and policy implementation over the patient journey: the potential of coronary heart disease registers

Coronary heart disease registers offer considerable potential for providing increased support for practitioners, facilitating improvements in patient care, and allowing efficient monitoring of care provision and outcomes.

Biochemical mode of action and differential activity of new ecdysone agonists against mosquitoes and moths

THQ (1-aroyl-4-(arylamino)-1,2,3,4-tetrahydroquinoline) compounds were identified by FMC Corporation in cell-based assays that used ecdysone receptors from Drosophila melanogaster, Heliothis virescens, or Plodia interpunctata. THQ compounds showed weak insecticidal activity against H. virescens and, therefore, were not developed further. Several ecdysone agonists based on THQ chemotype have been synthesized and tested for their activity against a number of EcRs in transactivation assays. The THQ compound, RG-120768, activated AaEcR (EcR from A. aegypti) but did not activate EcRs cloned from other insects. In transactivation assays, all six THQ ligands tested functioned through AaEcR but not through CfEcR (EcR from Choristoneura fumiferana). Three THQ compounds that showed higher activity in transactivation assays were tested in tobacco bud moth, H. virescens, and yellow fever mosquito, A. aegypti. These compounds showed higher activity in A. aegypti when compared to their activity in H. virescens. These data show that the THQ ligands are a new class of non-steroidal ecdysone agonists with preferential activity against mosquitoes.

HEPATOZOON SAURITUS: A POLYTOPIC HEMOGREGARINE OF THREE GENERA AND FOUR SPECIES OF SNAKES IN NORTH FLORIDA, WITH SPECIFIC IDENTITY VERIFIED FROM GENOME ANALYSIS

Hemogregarines from Thamnophis s. sirtalis, Coluber constrictor priapus, Elaphe obsoleta quadrivittata, and E. g. guttara in northern Florida appeared to be conspecific on the basis of similar gamonts from all the hosts and sporogonic stages obtained from 3 hosts. The resemblance of gamonts to those of Hepatozoon sauritus, described from T. sauritus sackenii in southern Florida, justified comparison of DNA isolates from the type infection of H. sauritus with samples from each of the northern Florida hosts and with a morphologically distinct species, H. sirtalis, from northern Florida. A nucleotide sequence (530 bp) alignment of the 18S ribosomal RNA gene revealed 2 hemogregarine haplotypes that varied at 15 sites (p distance = 2.8%), which included 10 transitions and 5 transversions. Two well-supported clusters (100% bootstrap support) were revealed by a neighbor-joining tree topology. One cluster included the type infection of H. sauritus and all 4 of the other samples from the northern Florida hosts, with samples of H. sirtalis comprising a second cluster. Hepatozoon sauritus, therefore, is a polytopic species in contrast to the 8 other Hepatozoon species thus far described from snakes in Florida, each of which appears to parasitize a single host species.

Transfectant mosaic spheroids: a new model for evaluation of tumour cell killing in targeted radiotherapy and experimental gene therapy

BACKGROUND

We describe an in vitro tumour model for targeted radiotherapy and gene therapy that incorporates cell population heterogeneity.

MATERIALS AND METHODS

Transfectant mosaic spheroids (TMS) and transfected mosaic monolayers (TMM) are composed of two cell populations derived from a single cell line. The cells of one population were transfected with the noradrenaline transporter gene (NAT), allowing active uptake of a radiolabelled targeting agent meta-[131I]iodobenzylguanidine ([131I]MIBG); the other population of cells was derived from the same parent line and transfected with a marker gene - green fluorescent protein (GFP). After treatment with [131I]MIBG, cell kill was determined in TMM by clonogenic assay and in TMS by clonogenic assay and spheroid growth delay.

RESULTS

We have used the TMS model to assess the 'radiological bystander effect' (radiation cross-fire) conferred by the beta-emitting radiopharmaceutical [131I] MIBG whose cellular uptake is facilitated by the transfected gene encoding NAT. We show that cell killing by [131I]MIBG in both TMS and TMM cultures increased in direct proportion to the fraction of NAT-transfected cells and that the degree of cell killing against fraction transfected was greater in TMS, suggestive of a greater bystander effect in the three-dimensional culture system.

CONCLUSIONS

TMS provide a useful model for assessment of the effectiveness of targeted radiotherapy in combination with gene therapy when less than 100% of the target cell population is expressing the NAT transgene. Further, this novel model offers the unique opportunity to investigate radiation-induced bystander effects and their contribution to cell cytotoxicity in radiotherapy and other gene therapy applications.

Intron/exon organization and polymorphisms of the PLK3/PRK gene in human lung carcinoma cell lines

PLK3/PRK, a conserved polo family protein serine/threonine kinase, plays a significant role at the onset of mitosis and mitotic progression. Recently, PLK3/PRK has been shown to induce apoptosis when overexpressed in cell lines and is also implicated in cell proliferation and tumor development. Forty lung tumor cell lines were used for single-strand confirmation polymorphism (SSCP) analysis and DNA sequencing to examine the mutational status of PLK3/PRK. No missense or nonsense mutations were revealed in the lung carcinoma cell lines examined. However, three polymorphisms were identified as: a G to A at position 720, an A to G at 1053, and a G to C at 1275. Intron/exon boundaries were determined by amplification of genomic DNA with PLK3/PRK exon-specific primers. The amplification products with increased size relative to the cDNA were sequenced. Fifteen exons throughout the open reading frame were characterized. None of the introns were exceptionally large, typically ranging from 100-300 basepairs in length. These results suggest that although PLK3/PRK expression is downregulated in a majority of lung carcinoma samples, mutational inactivation of the coding sequence of the PLK3/PRK gene appears to be a rare event in lung cancer.

A developmental study of the Desert hedgehog-null mouse testis

Desert hedgehog (Dhh) is a cell-signaling molecule that was first discovered in Drosophila. A unique testicular phenotype has been described in neonatal and adult Dhh-null animals that includes anastomotic seminiferous tubules, pertitubular cell abnormalities, and absence of adult-type Leydig cells. In the present study, we addressed the developmental basis for the abnormalities previously described for the adult Dhh-null phenotype. The source of Dhh is the Sertoli cell, and receptors are localized on peritubular cells and possibly Leydig cells. The development of testes from Dhh-null mouse embryos was studied using light and electron microscopy at 11.5, 12.5, 13.5, and 16.5 days postcoitum (dpc) and was compared with that in control Dhh heterozygous and wild-type embryos. Dhh-null and control testes were generally similar during the period of early cord formation (11.5-12.5 dpc). By 13.5 dpc, the basal lamina delimiting the cords was lacking in some regions and disorganized in Dhh-null testes, and occasional germ cells were seen outside cords. At 16.5 dpc, these defects were more prominent and cord organization was less well defined than in controls. In addition, there were numerous extracordal germ cells, some of which were partially enclosed by a somatic cell of unknown identity. Numerous fibroblast-like cells, apparently secreting collagen and basal lamina, characterized the interstitium of the Dhh-null testis. These defects likely stem from abnormal peritubular stimulation due to the lack of Dhh, leading to the abnormalities seen in the developmental stages studied here and in the adult testis.

Multisite pooling study using ligase chain reaction in screening for genital Chlamydia trachomatis infections

BACKGROUND

Ligase chain reaction (LCR), a nucleic acid amplification assay, is a highly specific and sensitive test for detecting Chlamydia trachomatis in cervical and urethral swabs as well as first-void urine specimens.

GOAL

To examine the suitability of using the LCR test to detect C trachomatis in pooled cervical specimens.

STUDY DESIGN

The performance of LCR in pooled specimens was compared with individual specimen testing at six laboratories using 3,170 cervical swab specimens randomly selected from specimens received for routine testing in the participating laboratories. These samples then were combined consecutively into 634 pools of 5 specimens and 317 pools of 10 specimens. A reduced sample to cutoff ratio of 0.2 or more was used for the pooled specimens.

RESULTS

Of the 188 positive specimens (98.9%), 186 were identified when single specimens were analyzed. When pools of 5 or 10 specimens were evaluated, 99.5% and 98.9% of the positive swabs, respectively, were identified correctly. Two positive specimens were detected only through pooling.

CONCLUSIONS

Pooling samples for detection of C trachomatis by LCR is sensitive and specific. Depending on the prevalence of infection (positivity), LCR testing may result in cost savings, as compared with individual testing of specimens.

Indolopyridoquinazoline alkaloid from Leptothyrsa sprucei

The indolopyridoquinazoline alkaloid, 3-hydoxyrutaecarpine, was isolated from Leptothyrsa sprucei, along with 8-methoxypsoralen, 5-methoxypsoralen, imperatorin, isoimperatorin, kaempferol 3-O-alpha-L-rhamnopyranoside, clematine and cnidioside B. The usefulness of the gradient 1H-15N HMBC NMR spectroscopy in the structure elucidation of 3-hydroxyrutaecarpine is noted.

Phenolic compounds from Miconia myriantha inhibiting Candida aspartic proteases

Assay-guided fractionation of the ethanol extract of the twigs and leaves of Miconia myriantha yielded two new compounds, mattucinol-7-O-[4' ',6' '-O-(S)-hexahydroxydiphenoyl]-beta-D-glucopyranoside (1) and mattucinol-7-O-[4' ',6' '-di-O-galloyl]-beta-D-glucopyranoside (2), along with mattucinol-7-O-beta-D-glucopyranoside (3), ellagic acid (4), 3,3'-di-O-methyl ellagic acid-4-O-beta-D-xylopyranoside, and gallic acid. Complete (1)H and (13)C NMR assignments of compound 1, which possesses a hexahydroxydiphenoyl unit, were achieved using the HMBC technique optimized for small couplings to enhance the four-bond and two-bond H/C correlations. Compounds 1 and 4 showed inhibitory effects against Candida albicans secreted aspartic proteases, with IC(50) of 8.4 and 10.5 microM, respectively.

A new naphthopyrone derivative from Cassia quinquangulata and structural revision of quinquangulin and its glycosides

A novel naphthopyrone derivative, named quinquangulone (1), has been isolated from Cassia quinquangulata, along with the known compounds quinquangulin (2) and its two glycosides (3 and 4), rubrofusarin (5) and its two glycosides (6 and 7), nor-rubrofusarin (8) and its 6-O-glucoside (9), and three stilbenes (10-12). The structure of quinquangulone was established by spectral interpretation as 5,9-dihydroxy-8-methoxy-2,9-dimethyl-6-oxo-4H,6H,9H-naphtho-[2,3-b]pyran-4-one. Reinvestigation of the NMR spectra of quinquangulin led to revision of its structure as 5,6-dihydroxy-8-methoxy-2,9-dimethyl-4H-naphtho[2,3-b]pyran-4-one (2a). The structures of two quinguangulin glycosides, 3 and 4, were also revised accordingly. Compound 2a exhibited activity against Staphylococcus aureus and methicillin-resistant S. aureus (MIC, 3.125 and 6.25 microg/mL, respectively).

A novel gene causing a mendelian audiogenic mouse epilepsy

Frings mice are a model of generalized epilepsy and have seizures in response to loud noises. This phenotype is due to the autosomal recessive inheritance of a single gene on mouse chromosome 13. Here we report the fine genetic and physical mapping of the locus. Sequencing of the region led to identification of a novel gene; mutant mice are homozygous for a single base pair deletion that leads to premature termination of the encoded protein. Interestingly, the mRNA levels of this gene in various tissues are so low that the cDNA has eluded detection by standard library screening approaches. Study of the MASS1 protein will lead to new insights into regulation of neuronal excitability and a new pathway through which dysfunction can lead to epilepsy.

New indole alkaloids from the bark of Nauclea orientalis

Four new alkaloids, nauclealines A (1) and B (2) and naucleosides A (3) and B (4), together with six known compounds, strictosamide (5), vincosamide (6), pumiloside (7), kelampayoside A, sitosterol, and sitosteryl beta-D-glucoside, were isolated from the bark of Nauclea orientalis. The structures of 1-4 were elucidated using 1D and 2D NMR spectral methods, including COSY, DEPT, HMQC, (13)C-(1)H HMBC, and (15)N-(1)H HMBC.

Functional expression, characterization, and purification of the catalytic domain of human 11-beta -hydroxysteroid dehydrogenase type 1

11-beta-hydroxysteroid dehydrogenase type 1 catalyzes the conversion of cortisone to hormonally active cortisol and has been implicated in the pathogenesis of a number of disorders including insulin resistance and obesity. The enzyme is a glycosylated membrane-bound protein that has proved difficult to purify in an active state. Extracted enzyme typically loses the reductase properties seen in intact cells and shows principally dehydrogenase activity. The C-terminal catalytic domain is known to contain a disulfide bond and is located within the lumen of the endoplasmic reticulum, anchored to the membrane by a single N-terminal transmembrane domain. We report here the functional expression of the catalytic domain of the human enzyme, without the transmembrane domain and the extreme N terminus, in Escherichia coli. Moderate levels of soluble active protein were obtained using an N-terminal fusion with thioredoxin and a 6xHis tag. In contrast, the inclusion of a 6xHis tag at the C terminus adversely affected protein solubility and activity. However, the highest levels of active protein were obtained using a construct expressing the untagged catalytic domain. Nonreducing electrophoresis revealed the presence of both monomeric and dimeric disulfide bonded forms; however, mutation of a nonconserved cysteine residue resulted in a recombinant protein with no intermolecular disulfide bonds but full enzymatic activity. Using the optimal combination of plasmid construct and E. coli host strain, the recombinant protein was purified to apparent homogeneity by single step affinity chromatography. The purified protein possessed both dehydrogenase and reductase activities with a K(m) of 1.4 micrometer for cortisol and 9.5 micrometer for cortisone. This study indicates that glycosylation, the N-terminal region including the transmembrane helix, and intermolecular disulfide bonds are not essential for enzyme activity and that expression in bacteria can provide active recombinant protein for future structural and functional studies.

Antimalarial, cytotoxic, and antifungal alkaloids from Duguetia hadrantha

Bioassay-guided isolation of Duguetia hadrantha yielded two new 4,5-dioxo-1-azaaporphinoids, hadranthine A (1) and hadranthine B (2), together with the known alkaloids imbiline-1 (3), sampangine (4), and 3-methoxysampangine (5), whose structures were determined primarily from 2D-NMR 1H-13C HMBC, and 1H-15N HMBC experiments. This is the first report of the co-occurrence of the copyrine alkaloids 4 and 5, as well as the first report of either copyrine or imbiline type alkaloids from a Duguetia species. Compounds 1, 4, and 5 demonstrated in vitro antimalarial activity against Plasmodium falciparum (W-2 clone), while 2 was inactive. Instead, 2 showed in vitro cytotoxicity to selected human cancer cell lines (IC50 = 3-6 microg/mL against SK-MEL, KB, BT-549, and SK-OV-3), and 4 was also cytotoxic to human malignant melanoma (IC50 = 0.37 microg/mL). Sampangine (4) also inhibited cell aggregation with a MIC value of <0.15 microg/mL, while 3-methoxysampangine (5) was only weakly active.

Dihydrochalcones from Piper longicaudatum

Bioactivity-guided fractionation of an ethanolic extract of the leaves and twigs of Piper longicaudatum Trelease & Yunker (Piperaceae) resulted in the isolation of one new (1) and three known (2-4) dihydrochalcones. The known compounds are: 2',6'-dihydroxy-4'-methoxydihydrochalcone (2), 2',6',4-trihydroxy-4'-methoxydihydrochalcone (asebogenin) (3), and 2'-hydroxy-4'-methoxy-2'-[1-hydroxy-1-methylethyl]-2",3"-dihy- drofurano[4",5":5',6"]-3"-[2-hydroxy-5-methoxycarbonylphe- nyl]dihydrochalcone (piperaduncin B) (4). The new compound is 2'-hydroxy-4'-methoxy-2"-[2-hydroxy-5-methoxycarbonyl- phenyl]-furano[4",5":5',6']-dihydrochalcone (longicaudatin) (1). Compounds 1-4 were tested for antibacterial activity against S. aureus and methicillin-resistant S. aureus (MRSA); only compound 3 showed inhibitory activity (IC50 of 10 and 4.5 micrograms/ml, respectively).

Resolution and absolute configuration of naturally occurring auronols

Resolution of racemic 2-benzyl-2-hydroxy-1-benzofuran-3(2H)-ones (auronols) and CD data of the ensuing enantiomers permit assessment of the absolute configuration at the single stereocenter.

Antifungal chalcones from Maclura tinctoria

Five prenylated flavonoids, including one new natural product, were isolated from an ethanol extract of the leaves of Maclura tinctoria (L.) Gaud. The new compound has been characterized as 2',4',4,2''-tetrahydroxy-3'-[3''-methylbut-3''-enyl]chalcone (1). The known compounds were identified as 2',4',4-trihydroxy-3'-[3''-methylbut-3''-enyl]chalcone (isobavachalcone) (2), 4,2'-dihydroxy-2''-[1-hydroxy-1-methylethyl]-2'',3''-dihydrofurano[4'',5'':3',4']chalcone (bakuchalcone) (3), 4,4',5''-trihydroxy-6'',6''-dimethyldihydropyrano[2'',3'':5',6'']chalcone (bavachromanol) (4), and 5,7,3',4'-tetrahydroxy-6,8-diprenylisoflavone (6,8-diprenylorobol) (5). All the isolated compounds were evaluated against the AIDS-related opportunistic fungal pathogens, Candida albicans and Cryptococcus neoformans. Compound 2 was active against both yeasts.

A new dammarane-type triterpene glycoside from Polyscias fulva

A new dammarane-type triterpene glycoside, polysciasoside A (1), and three known compounds have been isolated from the leaves of Polyscias fulva. The structure of the new compound was established as 12-oxo-3beta,16beta,20(S)-trihydroxydammar-24-ene-3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside.

Desert hedgehog (Dhh) gene is required in the mouse testis for formation of adult-type Leydig cells and normal development of peritubular cells and seminiferous tubules

Testes from adult and prepubertal mice lacking the Desert hedgehog (DHH:) gene were examined in order to describe further the role of Dhh in spermatogenesis because, in a previous report, DHH:-null male mice were shown to be sterile. Dhh is a signaling molecule expressed by Sertoli cells. Its receptor, patched (Ptc), has been previously localized to Leydig cells and is herein described as being localized also to peritubular cells. Two phenotypes of the mice were observed: masculinized (7.5% of DHH:-null males) and feminized (92.5%), both of which displayed abnormal peritubular tissue and severely restricted spermatogenesis. Testes from adult feminized animals lacked adult-type Leydig cells and displayed numerous undifferentiated fibroblastic cells in the interstitium that produced abundant collagen. The basal lamina, normally present between the myoid cells and Sertoli cells, was focally absent. We speculate that the abnormal basal lamina contributed to other characteristics, such as extracordal gonocytes, apolar Sertoli cells, and anastomotic seminiferous tubules. The two DHH:-null phenotypes described have common peritubular cell defects that may be indicative of the essential role of peritubular cells in development of tubular morphology, the differentiation of Leydig cells, and the ultimate support of spermatogenesis.

Clusterin gene in rat sertoli cells is regulated by a core-enhancer element

Clusterin is a ubiquitous glycoprotein that is promiscuously expressed at a low basal level but can be highly induced by a variety of stress conditions. In contrast, in some secretory cells associated with tissue-fluid interfaces such as the Sertoli cells in the testis, clusterin demonstrates high constitutive expression. In this study, we address the mechanisms that regulate the constitutive expression of the clusterin gene by using primary cultures of immature rat Sertoli cells. We have identified a region of the rat clusterin gene promoter that activated transcription only in Sertoli cells and that mapped between positions -426 and -311. Sequence analysis of this region revealed a high concentration of potential regulatory elements. Using gel-shift assays combined with hydroxyl radical footprinting, we identified the elements recognized by the Sertoli cell nuclear factors. Comparison of the interactions with this region of the nuclear factors from different cell types demonstrated that recognition of the core-enhancer element is specific for the Sertoli cells, and in vitro, the core region was recognized by the transcription factor CBF. Transient transfections showed that a core enhancer is responsible for more than a half of the total promoter activity and is an essential element for the cell-specific activity of the Sertoli-specific region. In addition to the core enhancer, tandem Sp1 sites are also required for maximal activity of this region.

Prevalence of vacuolar lesions consistent with scrapie in the brains of healthy cull sheep of the Shetland Islands

To determine the levels of background scrapie-like pathology in the brains of clinically normal adult sheep, the brains of 1106 sheep from 28 known scrapie-infected flocks and nine apparently uninfected flocks were examined during 1998 and 1999. One per cent of the brains had vacuolar pathology and disease-specific accumulations of prion protein consistent with a diagnosis of scrapie. All the positive animals had at least one allele of the prion protein gene encoding valine at codon 136, and originated from flocks in which cases of clinical scrapie had been confirmed within the last four years. The parasympathetic nucleus of the vagal nerve was the most consistently and severely affected nucleus in the medulla oblongata, suggesting that the infection enters the brain via ascending fibres of the vagus nerve.

Electric-field-induced soft-mode hardening in SrTiO3 films

We have studied electric-field-induced Raman scattering in SrTiO3 thin films using an indium-tin-oxide/SrTiO3/SrRuO3 structure grown by pulsed laser deposition. The soft mode polarized along the field becomes Raman active. Experimental data for electric-field-induced hardening of the soft modes and the tuning of the static dielectric constant are in agreement described by the Lyddane-Sachs-Teller formalism. The markedly different behavior of the soft modes in thin films from that in the bulk is explained by the existence of local polar regions.