Novel Electronic Health Records-Based Consultation Workflow Improves Time to Operating Room for Vascular Surgery Patients in an Acute Setting

BACKGROUND

Inefficient clinical workflows can have downstream effects of increased costs, poor resource utilization, and worse patient outcomes. The surgical consultation process can be complex with unclear communication, potentially delaying care for patients requiring time-sensitive intervention in an acute setting. A novel electronic health records (EHR)-based workflow was implemented to improve the consultation process. After implementation, we assessed the impact of this initiative in patients requiring vascular surgery consultation.

METHODS

An EHR-driven consultation workflow was implemented at a single institution, standardizing the process across all consulting services. This order-initiated workflow automated notification to clinicians of consult requests, communication of patient data, patient addition to consultants' lists, and tracking consult completion. Preimplementation (1/1/2020-1/31/2022) and postimplementation (2/1/2022-12/4/2022) vascular surgery consultation cohorts were compared to evaluate the impact of this initiative on timeliness of care.

RESULTS

There were 554 inpatient vascular surgery consultations (255 preimplementation and 299 postimplementation); 45 and 76 consults required surgery before and after implementation, respectively. The novel workflow resulted in placement of a consult note 32 min faster than preimplementation (preimplementation: 462 min, postimplementation: 430 min, P = 0.001) for all vascular surgery consults. Furthermore, vascular surgery patients with ASA class III or IV status requiring an urgent or emergent operation were transported to the operating room 63.3% faster after implementation of the workflow (preimplementation: 284 min, postimplementation: 180 min, P = 0.02). There were no differences in procedure duration, postoperative disposition, or intraoperative complication rates.

CONCLUSIONS

We implemented a novel workflow utilizing the EHR to standardize and automate the consultation process in the acute inpatient setting. This institutional initiative significantly improved timeliness of care for vascular surgery patients, including decreased time to operation. Innovations such as this can be further disseminated across shared EHR platforms across institutions, representing a powerful tool to increase the value of care in vascular surgery and healthcare overall.

Conditional Survival in Lung Transplantation: An Organ Procurement and Transplantation Network Database Analysis

Lung transplantation survival estimates are traditionally reported as fixed 1-, 5-, and 10-year mortality rates. Alternatively, this study aims to demonstrate how conditional survival models can provide useful prognostic information tailored to the time a recipient has already survived from the date of transplantation. Recipient data was obtained from the Organ Procurement and Transplantation Network database. Data from 24,820 adult recipients over age 18 who received a lung transplant between 2002 and 2017 were included in the study. Five-year observed conditional survival estimates were calculated by recipient age, sex, race, transplant indication, transplant type ( i.e. , single or double), and renal function at the time of transplantation. Significant variability exists in conditional survival following lung transplantation. Each specific recipient characteristic significantly impacted conditional survival during at least one time point in the first 5 years. Younger age and double lung transplantation were the two most positive predictors of improved conditional survival consistently throughout the 5-year study period. Conditional survival in lung transplantation recipients changes over time and across recipient characteristics. Hazards of mortality are not fixed and need to be dynamically evaluated as a function of time. Conditional survival calculations can provide more accurate prognostic predictions than unconditional survival estimates.

Appraisal of Donation After Circulatory Death: How Far Could We Expand the Heart Donor Pool?

BACKGROUND

the incidence of organ donation after circulatory death (DCD) is increasing; however, heart use has lagged behind other solid organs. Ex vivo perfusion devices are under United States Food and Drug Administration review for use in DCD heart recovery. This study sought to measure the potential increase in the donor pool if DCD heart donation becomes widely adopted.

METHODS

DCD donor data were obtained from Organ Procurement and Transplantation Network database. Selection criteria included donor age 18 to 49 years, donors meeting Maastricht III criteria, warm ischemia time ≤30 minutes, and donation between 2015 and 2020. Exclusion criteria were coronary disease, prior myocardial infarction, ejection fraction <0.50, significant valve disease, bacteremia, pulmonary capillary wedge pressure >15 mm Hg, and history of HIV/hepatitis C virus infections.

RESULTS

There were 12 813 DCD donors during this period, of which 3528 met study criteria, and 70 hearts (2%) were transplanted. The use of DCD hearts would represent an additional 48 heart transplants per month, which corresponds to a 21% (3458 of 16 521) increase across the country. Median warm ischemia was 23 minutes, with no difference between hearts that were or were not transplanted (23 vs 22.5 minutes, P = .97). The frequency with which other organs were successfully transplanted was kidney, 92%; liver, 44%; lung, 7%; intestine, 0%; and pancreas, 2%.

CONCLUSIONS

Wide adoption of DCD heart transplantation could yield a substantial increase in the donor pool size, with approximately 580 additional organs being available each year across the United States. This would represent the largest increase in the donor pool in the modern era of heart transplantation.

Measuring the effect of the COVID-19 pandemic on solid organ transplantation

Background

The COVID-19 pandemic has uniquely affected the United States. We hypothesize that transplantation would be uniquely affected.

Methods

In this population-based cohort study, adult transplantation data were examined as time series data. Autoregressive-integrated-moving-average models of transplantation rates were developed using data from 1990 to 2019 to forecast the 2020 expected rates in a theoretical scenario if the pandemic did not occur to generate observed-to-expected (O/E) ratios.

Results

32,594 transplants were expected in 2020, and only 30,566 occurred (O/E 0.94, CI 0.88–0.99). 58,152 waitlist registrations were expected and 50,241 occurred (O/E 0.86, CI 0.80–0.94). O/E ratios of transplants were kidney 0.92 (0.86–0.98), liver 0.96 (0.89–1.04), heart 1.05 (0.91–1.23), and lung 0.92 (0.82–1.04). O/E ratios of registrations were kidney 0.84 (0.77–0.93), liver 0.95 (0.86–1.06), heart 0.99 (0.85–1.18), and lung 0.80 (0.70–0.94).

Conclusions

The COVID-19 pandemic was associated with a significant deficit in transplantation. The impact was strongest in kidney transplantation and waitlist registration.

Activated PMN Exosomes: Pathogenic Entities Causing Matrix Destruction and Disease in the Lung

Here, we describe a novel pathogenic entity, the activated PMN (polymorphonuclear leukocyte, i.e., neutrophil)-derived exosome. These CD63⁺/CD66b⁺ nanovesicles acquire surface-bound neutrophil elastase (NE) during PMN degranulation, NE being oriented in a configuration resistant to α1-antitrypsin (α1AT). These exosomes bind and degrade extracellular matrix (ECM) via the integrin Mac-1 and NE, respectively, causing the hallmarks of chronic obstructive pulmonary disease (COPD). Due to both ECM targeting and α1AT resistance, exosomal NE is far more potent than free NE. Importantly, such PMN-derived exosomes exist in clinical specimens from subjects with COPD but not healthy controls and are capable of transferring a COPD-like phenotype from humans to mice in an NE-driven manner. Similar findings were observed for another neutrophil-driven disease of ECM remodeling (bronchopulmonary dysplasia [BPD]). These findings reveal an unappreciated role for exosomes in the pathogenesis of disorders of ECM homeostasis such as COPD and BPD, providing a critical mechanism for proteolytic damage.

The neutrophil chemoattractant peptide proline-glycine-proline is associated with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by unrelenting polymorphonuclear neutrophil (PMN) inflammation and vascular permeability. The matrikine proline-glycine-proline (PGP) and acetylated PGP (Ac-PGP) have been shown to induce PMN inflammation and endothelial permeability in vitro and in vivo. In this study, we investigated the presence and role of airway PGP peptides in acute lung injury (ALI)/ARDS. Pseudomonas aeruginosa-derived lipopolysaccharide (LPS) was instilled intratracheally in mice to induce ALI, and increased Ac-PGP with neutrophil inflammation was noted. The PGP inhibitory peptide, arginine-threonine-arginine (RTR), was administered (it) 30 min before or 6 h after LPS injection. Lung injury was evaluated by detecting neutrophil infiltration and permeability changes in the lung. Pre- and posttreatment with RTR significantly inhibited LPS-induced ALI by attenuating lung neutrophil infiltration, pulmonary permeability, and parenchymal inflammation. To evaluate the role of PGP levels in ARDS, minibronchoalveolar lavage was collected from nine ARDS, four cardiogenic edema, and five nonlung disease ventilated patients. PGP levels were measured and correlated with Acute Physiology and Chronic Health Evaluation (APACHE) score, P a O 2 to F I O 2 (P/F), and ventilator days. PGP levels in subjects with ARDS were significantly higher than cardiogenic edema and nonlung disease ventilated patients. Preliminary examination in both ARDS and non-ARDS populations demonstrated PGP levels significantly correlated with P/F ratio, APACHE score, and duration on ventilator. These results demonstrate an increased burden of PGP peptides in ARDS and suggest the need for future studies in ARDS cohorts to examine correlation with key clinical parameters.

Pregnancy Outcomes Related to Mycophenolate Exposure in Female Kidney Transplant Recipients

In 2012, the U.S. Food and Drug Administration issued guidelines advising kidney transplant recipients (KTRs) to discontinue mycophenolate (MPA) in preparation for pregnancy. Little is known about how this guidance has affected pregnancy and graft outcomes. The purpose of this retrospective cohort study was to investigate any association between the discontinuation of MPA and KTR pregnancy and graft outcomes. Data from the National Transplantation Pregnancy Registry included 382 cases in which KTRs managed on MPA became pregnant. Overall, 22 variables, including the time in which a KTR discontinued MPA, were assessed across four end points: miscarriages, birth defects, and 2- and 5-year postpartum graft loss. Birth defects and miscarriages were similar among KTRs who discontinued MPA >6 and <6 weeks prior to pregnancy and during the first trimester. In contrast, discontinuing MPA during the second trimester or later significantly increased the risk of miscarriages (odds ratio [OR] 9.35, 95% confidence interval [CI] 4.31-20.00, p < 0.001) and birth defects (OR 6.06, 95% CI 1.96-18.87, p = 0.002). Discontinuing MPA <6 weeks prior to pregnancy was associated with an increased risk of 5-year graft loss. For the fetus, there is value to discontinuing MPA anytime prior to the second trimester. Adhering to current guidelines does not negatively affect graft survival.

Life-history plasticity in female threespine stickleback

The postglacial adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus) has been widely used to investigate the roles of both adaptive evolution and plasticity in behavioral and morphological divergence from the ancestral condition represented by present-day oceanic stickleback. These phenotypes tend to exhibit high levels of ecotypic differentiation. Population divergence in life history has also been well studied, but in contrast to behavior and morphology, the extent and importance of plasticity has been much less well studied. In this review, we summarize what is known about life-history plasticity in female threespine stickleback, considering four traits intimately associated with reproductive output: age/size at maturation, level of reproductive effort, egg size and clutch size. We envision life-history plasticity in an iterative, ontogenetic framework, in which females may express plasticity repeatedly across each of several time frames. We contrast the results of laboratory and field studies because, for most traits, these approaches give somewhat different answers. We provide ideas on what the cues might be for observed plasticity in each trait and, when possible, we inquire about the relative costs and benefits to expressed plasticity. We end with an example of how we think plasticity may play out in stickleback life history given what we know of plasticity in the ancestor.

Rapid shifts in multiple life history traits in a population of threespine stickleback

Measurement of the rate of phenotypic or genetic change provides data bearing on many questions of fundamental interest to biologists, including how fast changes can proceed, whether shifts occur gradually or in bursts and how long high rates of change can be sustained. Because traits exist in functionally and genetically correlated suites, studies tracking many traits are likely to be the most informative. We quantify very rapid phenotypic changes in egg size (now smaller), clutch size (larger) and the age/size of both breeding females and males (younger, smaller) in an Alaskan population, with these traits shifting at rates from 0.13 to 0.30 haldanes over a 10-year period. In contrast, female reproductive effort and the allometric relationship of clutch size to body size changed little. These shifts appear to be caused by an altered selective landscape, with the presumed selective agent being increasing lake productivity. Some of the traits undoubtedly have at heritable component and thus represent genetic evolution as well as phenotypic.

Seasonal flowering and evolution: the heritage from Charles Darwin

To survive, plants optimise their seasonal flowering time and set seed to avoid extremes of the environment including frost, heat and drought. Additionally, pollination may need to be tightly regulated in time so that it coincides with flowering of other individuals and/or with the presence of bird or insect pollinators. It is now clear that plants use seasonal changes in natural light intensity, daylight duration and temperature to achieve reproducible timing of flowering year-in-year-out. In more recent studies, genetic and molecular approaches are beginning to provide a basis for understanding heritability, an essential component of Darwin's concept of evolution.

Comparative studies of active site-ligand interactions among various recombinant constructs of human beta-amyloid precursor protein cleaving enzyme

Amyloid precursor protein (APP) cleaving enzyme (BACE) is the enzyme responsible for beta-site cleavage of APP, leading to the formation of the amyloid-beta peptide that is thought to be pathogenic in Alzheimer's disease (AD). Hence, BACE is an attractive pharmacological target, and numerous research groups have begun searching for potent and selective inhibitors of this enzyme as a potential mechanism for therapeutic intervention in AD. The mature enzyme is composed of a globular catalytic domain that is N-linked glycosylated in mammalian cells, a single transmembrane helix that anchors the enzyme to an intracellular membrane, and a short C-terminal domain that extends outside the phospholipid bilayer of the membrane. Here we have compared the substrate and active site-directed inhibitor binding properties of several recombinant constructs of human BACE. The constructs studied here address the importance of catalytic domain glycosylation state, inclusion of domains other than the catalytic domain, and incorporation into a membrane bilayer on the interactions of the enzyme active site with peptidic ligands. We find no significant differences in ligand binding properties among these various constructs. These data demonstrate that the nonglycosylated, soluble catalytic domain of BACE faithfully reflects the ligand binding properties of the full-length mature enzyme in its natural membrane environment. Thus, the use of the nonglycosylated, soluble catalytic domain of BACE is appropriate for studies aimed at understanding the determinants of ligand recognition by the enzyme active site.

Cellular pharmacology of D-d4FC, a nucleoside analogue active against drug-resistant HIV

The backbone of effective highly active antiretroviral therapy regimens for the treatment of HIV infections currently contains at least two nucleosides. Among the features that influence the potency of each component of a regimen and the overall efficacy of the combination are the cellular uptake and bioconversion of nucleoside analogues to their active triphosphate form, and the extent of possible interactions in these steps that might occur when more than one nucleoside is used in a regimen. D-d4FC (Reverset), a new cytidine analogue with the ability to inhibit many nucleoside-resistant viral variants, was examined for these parameters. In phytohemaglutinin-stimulated human peripheral blood mononuclear cells, D-d4FC was taken up in a rapid (8 h to 50% maximal value), saturable (plateau above 10 microM parent nucleoside concentration) process, resulting in levels of D-d4FC triphosphate that should provide potent antiviral activity against a variety of virus genotypes. Based on measurement of antiviral effects in cell culture, additive and in some cases, synergistic interactions were observed with protease inhibitors, non-nucleoside reverse transcriptase inhibitors or other nucleosides, including cytidine analogues.

Inhibition of the replication of a hepatitis C virus-like RNA template by interferon and 3'-deoxycytidine

The development of low molecular weight inhibitors of hepatitis C virus (HCV) replication has been hindered by the lack of a good cell-based system that models the entire HCV replication cycle. To date the only two therapies approved for the treatment of HCV infection are interferon (IFN)-alpha and the nucleoside analogue, ribavirin. We have created a cell-based system that allows for the accurate quantification of the replication of an HCV-like RNA template by proteins that are encoded for by the HCV genome. The system consists of a cell line that constitutively produces luciferase in response to the production of functional HCV replicative proteins. The 293B4alpha cell line has been formatted into a semi-high throughput, cell-based screen for inhibitors of HCV replication. When these cells were treated with either IFN-alpha or -beta, luciferase production decreased in a dose-responsive manner. Counterscreening these molecules in another cell line, 293SVLuc, in which luciferase production in not dependent the presence of functional HCV proteins, showed that the inhibition of luciferase in the 293B4alpha cell line was due to inhibition of the replication of the HCV-like RNA template and not anti-cellular or -luciferase activity. Moreover, when the 293B4alpha cell line was treated with the ribonucleoside analogue, 3'-deoxycytidine, luciferase decreased in a dose-responsive manner. 3'-deoxyguanosine and 3'-deoxyuridine did not inhibit luciferase production and 3'-deoxyadenosine was too cytotoxic to determine if it had any anti-HCV activity.

A cell-based model of HCV-negative-strand RNA replication utilizing a chimeric hepatitis C virus/reporter RNA template

The inability of hepatitis C virus (HCV) to replicate in cell culture has hindered the discovery of antiviral agents against this virus. One of the biggest challenges has been to find a model that allows one to easily and accurately quantify the level of HCV RNA replication that is occurring inside the cell. In an attempt to solve this problem, we have created a plasmid pMJ050 that encodes a chimeric 'HCV-like' RNA that can act as a reporter for HCV RNA replication. This RNA consists of an antisense copy of the firefly luciferase sequence flanked by the 5' and 3' untranslated regions of the negative strand of the HCV RNA. If, in cells that contain functional HCV proteins, the chimeric RNA is recognized as a substrate for the viral RNA-dependent RNA polymerase, the chimeric RNA will be transcribed into the complementary strand. This RNA has a 5' HCV internal ribosome entry site and the luciferase sequence in the coding orientation, allowing translation of the RNA into biologically active luciferase. When pMJ050 was transfected into a cell line that is stably transfected with a cDNA copy of the HCV 1b genome, luciferase was produced in a manner that was dependent upon the presence of at least a functional HCV RNA-dependent RNA polymerase. In addition, we constructed a cell line, 293B4alpha that constitutively produced luciferase in response to the presence of functional HCV proteins. This system permits the accurate determination of the level of HCV RNA replication by the quantification of luciferase.

Selection of a thiazole urea-resistant variant of bovine viral diarrhoea virus that maps to the RNA-dependent RNA polymerase

By passing wild type bovine viral diarrhoea virus (BVDV) in increasing concentrations of DPC-A69280-29, a thiazole urea class compound that inhibits BVDV replication, we were able to select several variants of BVDV that exhibited decreased susceptibility to this compound. When the non-structural genes of these variants were sequenced and compared with wild type, only one change was common to all the variants that also exhibited resistance to DPC-A69280-29 (>10-fold increase in IC50). This change was a T-to-A transversion at position 11198 of the BVDV genome, which would cause a predicted substitution of isoleucine for phenylalanine at amino acid 78 of the RNA-dependent RNA polymerase (RdRp). This substitution would occur in a region of the BVDV RdRp which has been proposed to be important for the formation of the RdRp homodimer that is essential for the activity of the enzyme. However, since DPC-69280-29 inhibits BVDV replication by interfering with the initiation of viral RNA synthesis, we discuss the possibility that this region of the BVDV RdRp also may play a role in the initiation process. Furthermore, since this region is located fairly close to the template RNA, we also propose that the role it plays may involve either template selection, stabilization or processivity.

Potency of nonnucleoside reverse transcriptase inhibitors (NNRTIs) used in combination with other human immunodeficiency virus NNRTIs, NRTIs, or protease inhibitors

Efavirenz and a series of related quinazolinone nonnucleoside inhibitors of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) were evaluated in a series of two-drug combinations with several nucleoside RT inhibitors (NRTIs), nonnucleoside RT inhibitors (NNRTIs), and protease inhibitors (PIs). These combinations were tested in an established HIV-1 RT enzyme assay and a cell-based yield reduction assay with HIV-1 (replicative form [RF])-infected MT-2 cells. Synergy, additivity, and antagonism were determined in the two different assay systems by the method of Chou and Talalay (T.-C. Chou and P. Talalay, Adv. Enzyme Reg. 22:27-55, 1984). Efavirenz, DPC082, DPC083, DPC961, and DPC963 used in combination with the NRTIs zidovudine and lamivudine acted synergistically to inhibit RT activity in the HIV-1 RT enzyme assay and additively to slightly synergistically to inhibit HIV-1 (RF) replication in the yield reduction assay. The five NNRTIs in combination with the PI nelfinavir acted additively in the yield reduction assay to inhibit HIV-1 replication. Interestingly, efavirenz in combination with a second NNRTI acted additively to inhibit HIV-1 RT function in the enzyme assay, while it acted antagonistically to inhibit HIV-1 (RF) replication in the yield reduction assay. These data suggest that antiretroviral combination regimens containing multiple NNTRIs should be given thorough consideration before being used.

New technologies for chemical genetics

Chemical genetics, in which small molecules are used in lieu of mutations to study biological processes, requires large and diverse chemical libraries to specifically perturb different biological pathways. Here we describe a suite of technologies that enable chemical libraries prepared by split-pool solid phase synthesis to be screened in a diverse range of chemical genetic assays. Compounds are synthesized on 500 micron high-capacity polystyrene beads, and arrayed into individual wells of 384-well plates using a hand-held bead arrayer. Compounds are cleaved from synthesis beads using a chemically-resistant ceramic dispensing system, producing individual stock solutions of single compounds. Nanoliter volumes of these solutions are then transferred into assay plates using an array of stainless steel pins mounted on a robotic arm. We have designed reusable 1536- and 6144-well assay plates made of silicone rubber that can be cast in the laboratory and filled by hand. This integrated technology platform enables hundreds of biological assays to be performed from the product of a single synthesis bead, enabling the results of different chemical genetic experiments to be directly compared.

A one-bead, one-stock solution approach to chemical genetics: part 2

BACKGROUND

Chemical genetics provides a systematic means to study biology using small molecules to effect spatial and temporal control over protein function. As complementary approaches, phenotypic and proteomic screens of structurally diverse and complex small molecules may yield not only interesting individual probes of biological function, but also global information about small molecule collections and the interactions of their members with biological systems.

RESULTS

We report a general high-throughput method for converting high-capacity beads into arrayed stock solutions amenable to both phenotypic and proteomic assays. Polystyrene beads from diversity-oriented syntheses were arrayed individually into wells. Bound compounds were cleaved, eluted, and resuspended to generate 'mother plates' of stock solutions. The second phase of development of our technology platform includes optimized cleavage and elution conditions, a novel bead arraying method, and robotic distribution of stock solutions of small molecules into 'daughter plates' for direct use in chemical genetic assays. This library formatting strategy enables what we refer to as annotation screening, in which every member of a library is annotated with biological assay data. This phase was validated by arraying and screening 708 members of an encoded 4320-member library of structurally diverse and complex dihydropyrancarboxamides.

CONCLUSIONS

Our 'one-bead, multiple-stock solution' library formatting strategy is a central element of a technology platform aimed at advancing chemical genetics. Annotation screening provides a means for biology to inform chemistry, complementary to the way that chemistry can inform biology in conventional ('investigator-initiated') small molecule screens.

GAMYB-like genes, flowering, and gibberellin signaling in Arabidopsis

We have identified three Arabidopsis genes with GAMYB-like activity, AtMYB33, AtMYB65, and AtMYB101, which can substitute for barley (Hordeum vulgare) GAMYB in transactivating the barley alpha-amylase promoter. We have investigated the relationships between gibberellins (GAs), these GAMYB-like genes, and petiole elongation and flowering of Arabidopsis. Within 1 to 2 d of transferring plants from short- to long-day photoperiods, growth rate and erectness of petioles increased, and there were morphological changes at the shoot apex associated with the transition to flowering. These responses were accompanied by accumulation of GAs in the petioles (GA(1) by 11-fold and GA(4) by 3-fold), and an increase in expression of AtMYB33 at the shoot apex. Inhibition of GA biosynthesis using paclobutrazol blocked the petiole elongation induced by long days. Causality was suggested by the finding that, with GA treatment, plants flowered in short days, AtMYB33 expression increased at the shoot apex, and the petioles elongated and grew erect. That AtMYB33 may mediate a GA signaling role in flowering was supported by its ability to bind to a specific 8-bp sequence in the promoter of the floral meristem-identity gene, LEAFY, this same sequence being important in the GA response of the LEAFY promoter. One or more of these AtMYB genes may also play a role in the root tip during germination and, later, in stem tissue. These findings extend our earlier studies of GA signaling in the Gramineae to include a dicot species, Arabidopsis, and indicate that GAMYB-like genes may mediate GA signaling in growth and flowering responses.

GAMYB-like genes, flowering, and gibberellin signaling in Arabidopsis

We have identified three Arabidopsis genes with GAMYB-like activity, AtMYB33, AtMYB65, and AtMYB101, which can substitute for barley (Hordeum vulgare) GAMYB in transactivating the barley alpha-amylase promoter. We have investigated the relationships between gibberellins (GAs), these GAMYB-like genes, and petiole elongation and flowering of Arabidopsis. Within 1 to 2 d of transferring plants from short- to long-day photoperiods, growth rate and erectness of petioles increased, and there were morphological changes at the shoot apex associated with the transition to flowering. These responses were accompanied by accumulation of GAs in the petioles (GA(1) by 11-fold and GA(4) by 3-fold), and an increase in expression of AtMYB33 at the shoot apex. Inhibition of GA biosynthesis using paclobutrazol blocked the petiole elongation induced by long days. Causality was suggested by the finding that, with GA treatment, plants flowered in short days, AtMYB33 expression increased at the shoot apex, and the petioles elongated and grew erect. That AtMYB33 may mediate a GA signaling role in flowering was supported by its ability to bind to a specific 8-bp sequence in the promoter of the floral meristem-identity gene, LEAFY, this same sequence being important in the GA response of the LEAFY promoter. One or more of these AtMYB genes may also play a role in the root tip during germination and, later, in stem tissue. These findings extend our earlier studies of GA signaling in the Gramineae to include a dicot species, Arabidopsis, and indicate that GAMYB-like genes may mediate GA signaling in growth and flowering responses.

Inhibition of the bovine viral diarrhoea virus NS3 serine protease by a boron-modified peptidyl mimetic of its natural substrate

Bovine viral diarrhoea virus (BVDV) is closely related to hepatitis C virus (HCV), and has been used as a surrogate virus in drug development for HCV infection. Similar to HCV, BVDV-encoded NS3 serine proteinase is responsible for multiple cleavages in the viral polyprotein, generating mature NS4A, NS4B, NS5A and NS5B proteins. NS3-dependent cleavage sites of BVDV contain a strictly conserved leucine at P1, and either serine or alanine at P1'. The full length BVDV NS3/4A serine protease has been cloned and expressed in bacterial cells. The enzyme has been purified from the soluble portion of Escherichia coli via a two-step purification procedure employing chromatography on heparin resin and gel filtration. The protease activity was characterized using in vitro translated BVDV NS4A/B and NS5A/B polyprotein substrates. A boronic acid analogue of the BVDV NS4A/NS4B cleavage site was synthesized and shown to be an efficient inhibitor of the NS3 serine protease in vitro. The compound, designated DPC-AB9144-00, inhibited approximately 75% of the NS3/4 activity at 10 microM with the NS4A/B substrate. However, no antiviral activity was detected with DPC-AB9144-00 in BVDV-infected Madin-Darby bovine kidney cells at concentrations as great as 90 pM, suggesting permeability or that other cellular-derived limitations were present.

Long-day induction of flowering in Lolium temulentum involves sequential increases in specific gibberellins at the shoot apex

One challenge for plant biology has been to identify floral stimuli at the shoot apex. Using sensitive and specific gas chromatography-mass spectrometry techniques, we have followed changes in gibberellins (GAs) at the shoot apex during long day (LD)-regulated induction of flowering in the grass Lolium temulentum. Two separate roles of GAs in flowering are indicated. First, within 8 h of an inductive LD, i.e. at the time of floral evocation, the GA(5) content of the shoot apex doubled to about 120 ng g(-1) dry weight. The concentration of applied GA(5) required for floral induction of excised apices (R.W. King, C. Blundell, L.T. Evans [1993] Aust J Plant Physiol 20: 337-348) was similar to that in the shoot apex. Leaf-applied [(2)H(4)] GA(5) was transported intact from the leaf to the shoot apex, flowering being proportional to the amount of GA(5) imported. Thus, GA(5) could be part of the LD stimulus for floral evocation of L. temulentum or, alternatively, its increase at the shoot apex could follow import of a primary floral stimulus. Later, during inflorescence differentiation and especially after exposure to additional LD, a second GA action was apparent. The content of GA(1) and GA(4) in the apex increased greatly, whereas GA(5) decreased by up to 75%. GA(4) applied during inflorescence differentiation strongly promoted flowering and stem elongation, whereas it was ineffective for earlier floral evocation although it caused stem growth at all times of application. Thus, we conclude that GA(1) and GA(4) are secondary, late-acting LD stimuli for inflorescence differentiation in L. temulentum.

Evolution of floral meristem identity genes. Analysis of Lolium temulentum genes related to APETALA1 and LEAFY of Arabidopsis

Flowering (inflorescence formation) of the grass Lolium temulentum is strictly regulated, occurring rapidly on exposure to a single long day (LD). During floral induction, L. temulentum differs significantly from dicot species such as Arabidopsis in the expression, at the shoot apex, of two APETALA1 (AP1)-like genes, LtMADS1 and LtMADS2, and of L. temulentum LEAFY (LtLFY). As shown by in situ hybridization, LtMADS1 and LtMADS2 are expressed in the vegetative shoot apical meristem, but expression increases strongly within 30 h of LD floral induction. Later in floral development, LtMADS1 and LtMADS2 are expressed within spikelet and floret meristems and in the glume and lemma primordia. It is interesting that LtLFY is detected quite late (about 12 d after LD induction) within the spikelet meristems, glumes, and lemma primordia. These patterns contrast with Arabidopsis, where LFY and AP1 are consecutively activated early during flower formation. LtMADS2, when expressed in transgenic Arabidopsis plants under the control of the AP1 promoter, could partially complement the organ number defect of the severe ap1-15 mutant allele, confirming a close relationship between LtMADS2 and AP1.

A florigenic effect of sucrose in Fuchsia hybrida is blocked by gibberellin-induced assimilate competition

The use of gas chromatography-mass spectrometry-selected ion monitoring along with a (13)C internal standard has allowed sensitive measurements of the sucrose (Suc) content of individual shoot apices of Fuchsia hybrida. With intact plants, as the photosynthetic irradiance increased, so did shoot apex Suc content, reaching saturation at about 500 micromol m(-2) s(-1). These same plants flowered at the higher irradiances, remaining vegetative in 10-h short days at an irradiance of 230 micromol m(-2) s(-1). The strong correlation (r = 0.93) in these studies between flowering and shoot apex Suc content indicates a role for Suc as a stimulus to flowering in this species. However, Suc is not the long-day (LD) "florigen" of F. hybrida because 2 to 4 LD given as a 14-h low-irradiance photoperiod extension (10-15 micromol m(-2) s(-1)) induced flowering but without increase in shoot apex Suc content. Flowering induced by either pathway, the LD- or the Suc-mediated one, was inhibited by applying gibberellin (GA) to the shoot tip. Such inhibition of flowering by GA, at least for the LD pathway, was associated with a reduced apex Suc content, enhanced elongation of subapical stem tissue, and a reduced import into the shoot apex of leaf-sourced assimilate. Thus, our findings show how GA inhibits flowering of F. hybrida and confirm the importance of nutrient diversion in regulating flowering.

Phenylpropenamide derivatives as inhibitors of hepatitis B virus replication

A non-nucleoside class of compounds that inhibits the replication of hepatitis B virus (HBV) in cell culture has been discovered. A series of substituted analogues of phenylpropenamide 6 has been prepared and evaluated in the HepAD38 cellular assay. Structure-activity relationships of this series are discussed.

Calculated electric field induced in bundles of long cells in the human body when it is exposed to low-frequency electric fields

A theoretical analysis is made of the electric field induced in the interior of long cylindrical cells arranged in bundles of parallel cells embedded in the saline fluid in the human body exposed to extremely low-frequency (ELF) and very low-frequency (VLF) electric fields parallel to the length of the cells. Such bundles characterize muscle. The analysis parallels in many respects the earlier study of isolated long cells (King and Wu, Phys. Rev. E 58, 2363-2369, 1998) but has important added complications. It leads to a similar result: The field inside the membrane of each long cell is the same as the field just outside the membrane in the saline fluid; i.e., the membrane provides no shielding. While one might expect the presence of the neighboring cells to provide a shielding effect for each cell, the results of this study show quantitatively that this is not the case. In fact, the electric field in the interior of each of a bundle of long cells is seen to increase very slightly (of the order of 0.4%) when the cells in the bundle are moved close enough to be practically in contact.

Dissecting cellular processes using small molecules: identification of colchicine-like, taxol-like and other small molecules that perturb mitosis

BACKGROUND

Understanding the molecular mechanisms of complex cellular processes requires unbiased means to identify and to alter conditionally gene products that function in a pathway of interest. Although random mutagenesis and screening (forward genetics) provide a useful means to this end, the complexity of the genome, long generation time and redundancy of gene function have limited their use with mammalian systems. We sought to develop an analogous process using small molecules to modulate conditionally the function of proteins. We hoped to identify simultaneously small molecules that may serve as leads for the development of therapeutically useful agents.

RESULTS

We report the results of a high-throughput, phenotype-based screen for identifying cell-permeable small molecules that affect mitosis of mammalian cells. The predominant class of compounds that emerged directly alters the stability of microtubules in the mitotic spindle. Although many of these compounds show the colchicine-like property of destabilizing microtubules, one member shows the taxol-like property of stabilizing microtubules. Another class of compounds alters chromosome segregation by novel mechanisms that do not involve direct interactions with microtubules.

CONCLUSIONS

The identification of structurally diverse small molecules that affect the mammalian mitotic machinery from a large library of synthetic compounds illustrates the use of chemical genetics in dissecting an essential cellular pathway. This screen identified five compounds that affect mitosis without directly targeting microtubules. Understanding the mechanism of action of these compounds, along with future screening efforts, promises to help elucidate the molecular mechanisms involved in chromosome segregation during mitosis.

3rd International Conference on Therapies for Viral Hepatitis

This meeting was attended by several hundred delegates and covered, in lecture and poster presentations, recent developments in basic, applied and clinical research as they concern antiviral drug development for hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Below are summaries of presentations that are relevant to the development of antiviral drug resistance. Copyright 2000 Harcourt Publishers Ltd.

Hep AD38 Assay : A High-Throughput, Cell-Based Screen for the Evaluation of Compounds Against Hepatitis B Virus

Approximately 5% of the world's population has been infected with hepatitis B virus (HBV). Ten percent of these adults will become chronic carriers, as will 95% of the infants infected perinatally. Those that do become chronically infected with HBV are at increased risk of developing liver dysfunction, cirrhosis, and liver failure (1). In addition, they also have a greater incidence of heptocellular carcinoma (2). Approximately two million chronic carriers die annually from liver disease attributed to infection by HBV (3).

Chemistry or biology: which comes first after the genome is sequenced?

In drug discovery, chemical screening is performed after a protein's function has been determined. By screening for ligands that alter the function of a cell or an organism, new proteins that participate in poorly understood biological processes can be identified. Genomic and expression-cloning technologies can rapidly identify the protein targets of these ligands, enhancing the power of chemical screening as a tool for the initial stages of biological discovery.

Nerves in a human body exposed to low-frequency electromagnetic fields

Following a summarizing introduction in which the background research is reviewed and referenced, a detailed description is given of the properties of the elongated cell that constitutes a nerve axon. The functioning of the cell membrane is reviewed with reference to the transmission of a frequency-modulated signal. The need for successive regeneration by means of action potentials is described. Propagation within both myelinated and unmyelinated membranes is discussed. Currents and electric fields induced in the organs of the human body by external electric and magnetic fields are introduced and their determination reviewed. The interaction between these currents and electric fields and those involved in the propagation of a signal along a nerve axon is analyzed. It is shown that incident 60-Hz electric fields near high-voltage transmission lines do not induce large enough currents and fields in a nerve axon in the leg to disrupt a propagating signal. Scaling with respect to frequency and size is discussed. Surface sensations due to exposure to electric fields in the 5-15-kV/m range are analyzed. It is concluded that exposure to the electromagnetic field of a 60-Hz high-voltage transmission line or a 10-30-kHz high-power transmitting antenna should have no observable effect on the normal functioning of nerves.

A standardized letter of recommendation for residency application

Emergency medicine (EM) program directors have expressed a desire for more evaluative data to be included in application materials. This is consistent with frustrations expressed by program directors of multiple specialties, but mostly by those in specialties with more competitive matches. Some of the concerns about traditional narrative letters of recommendation included lack of uniform information, lack of relative value given for interval grading, and a perception of ambiguity with regard to terminology. The Council of Emergency Medicine Residency Directors established a task force in 1995 that created a standardized letter of recommendation form. This form, to be completed by EM faculty, requests that objective, comparative, and narrative information be reported regarding the residency applicant.

Small molecule inhibitor of mitotic spindle bipolarity identified in a phenotype-based screen

Small molecules that perturb specific protein functions are valuable tools for dissecting complex processes in mammalian cells. A combination of two phenotype-based screens, one based on a specific posttranslational modification, the other visualizing microtubules and chromatin, was used to identify compounds that affect mitosis. One compound, here named monastrol, arrested mammalian cells in mitosis with monopolar spindles. In vitro, monastrol specifically inhibited the motility of the mitotic kinesin Eg5, a motor protein required for spindle bipolarity. All previously known small molecules that specifically affect the mitotic machinery target tubulin. Monastrol will therefore be a particularly useful tool for studying mitotic mechanisms.

The electric field induced in the human body when exposed to electromagnetic fields at 1-30 MHz on shipboard

The electric field induced in the body of a man standing on the metal deck of a ship near a vertical antenna is determined analytically. Typical antennas for radio communication in the 1-30 MHz band are described and their near fields are calculated. The current induced in the man is determined by solving the relevant integral equation. Explicit formulas are obtained for the total axial current and the associated current densities and electric fields.

Long-day up-regulation of a GAMYB gene during Lolium temulentum inflorescence formation

Long-day exposure of the grass Lolium temulentum may regulate flowering via changes in gibberellin (GA) levels. Therefore, we have examined both GA levels and expression of a MYB transcription factor that is specific to the GA signal transduction pathway in monocots. This MYB gene from L. temulentum shows over 90% nucleotide identity with the barley and rice GAMYB genes, and, like them, gibberellic acid (GA3) up-regulates its expression in the seed. Furthermore, cDNAs of both the barley and L. temulentum GAMYB show the same simple patterns of hybridization with digests of L. temulentum genomic DNA. Compared with vegetative shoot apices of L. temulentum, the in situ mRNA expression of LtGAMYB does not change during the earliest steps of "floral" initiation at the apex. However, by 100 h (the double-ridge stage of flowering) its expression increased substantially and was highest in the terminal and lateral spikelet sites. Thereafter, expression declined overall but then increased within stamen primordia. Prior to increased LtGAMYB expression, long-day exposure sufficient to induce flowering led to increased (5- to 20-fold) levels of GA1 and GA4 in the leaf. Thus, increases first in GA level in the leaf followed by increased expression of LtGAMYB in the apex suggest important signaling and/or response roles in flowering.

Inhibition of human hepatitis B virus replication by AT-61, a phenylpropenamide derivative, alone and in combination with (-)beta-L-2',3'-dideoxy-3'-thiacytidine

AT-61, a member of a novel class of phenylpropenamide derivatives, was found to be a highly selective and potent inhibitor of human hepatitis B virus (HBV) replication in four different human hepatoblastoma cell lines which support the replication of HBV (i.e., HepAD38, HepAD79, 2.2.15, and transiently transfected HepG2 cells). This compound was equally effective at inhibiting both the formation of intracellular immature core particles and the release of extracellular virions, with 50% effective concentrations ranging from 0.6 to 5.7 microM. AT-61 (27 microM) was able to reduce the amount of HBV covalently closed circular DNA found in the nuclei of HepAD38 cells by >99%. AT-61 at concentrations of >27 microM had little effect on the amount of viral RNA found within the cytoplasms of induced HepAD38 cells but reduced the number of immature virions which contained pregenomic RNA by >99%. The potency of AT-61 was not affected by one of the mutations responsible for (-)-beta-L-2', 3'-dideoxy-3' thiacytidine (3TC) resistance in HBV, and AT-61 acted synergistic with 3TC to inhibit HBV replication. AT-61 (81 microM) was not cytotoxic or antiproliferative to several cell lines and had no antiviral effect on woodchuck or duck HBV, human immunodeficiency virus type 1, herpes simplex virus type 1, vesicular stomatitis virus, or Newcastle disease virus. Therefore, we concluded that the antiviral activity of AT-61 is specific for HBV replication and most likely occurs at one of the steps between the synthesis of viral RNA and the packaging of pregenomic RNA into immature core particles.

An examination of underlying physical principles. The interaction of power-line electromagnetic fields with the human body

A detailed examination of the scientific foundations contained in a number of recent articles has revealed some serious errors. The careful application of advanced mathematical-physical methods to study the penetration of externally applied electric fields into the organs and cells of the human body has obtained new and significant results [8, 9, 32]. Specifically, Eqs. (11) and (12) establish a definite relationship between an incident low-frequency electric field and the current, current density, and electric field induced in the body when the arms are in contact with it and the incident field is parallel to its length. Corresponding formulas with the arms raised are available [10] as are formulas for the current density and electric field in the organs of the body [9]. It is these currents and electric fields that must be used by biomedical research workers to determine their effect on living cells. The proposed interpretation of epidemiological data [31] indicates a risk of leukemia in children when the incident 50-60-Hz electric field generated by a high-voltage transmission line is Einc > or = 61 V/m. (23). The corresponding maximum electric field at approximately 10 m from a 440-kV transmission line is Einc approximately 2100 V/m [8, 9]. The electric fields induced in the different organs of the body by these electric fields are in the range 25.2 < or = E1z < or = 119 microV/m for Einc2z = 61 V/m and 0.87 < or = E1z < or = 4.1 mV/m for Einc2z = 2100 V/m [9]. These are in the range of applied fields in in vitro experiments, which showed significant effects on cells [4], and should serve as guidelines for such experiments.

The M539V polymerase variant of human hepatitis B virus demonstrates resistance to 2'-deoxy-3'-thiacytidine and a reduced ability to synthesize viral DNA

The cytosine analog 2'-deoxy-3'-thiacytidine (3TC) has been shown to be an effective treatment for chronic hepatitis B virus (HBV) infection. However, several liver transplant patients who were undergoing treatment with 3TC for HBV infection experienced a breakthrough of virus while on 3TC. The predominant virus found in these patients' sera contained either a valine or isoleucine for the methionine in the highly conserved YMDD nucleotide binding site in the HBV polymerase. To determine the biological relevance of the Met-to-Val substitution, we mutated a plasmid that contained a cDNA copy of the HBV pregenomic RNA such that when virus replication occurred during transient transfection of HepG2 cells, an M539V polymerase variant was produced. We found that in transiently transfected cells, this variant was approximately 330-fold less sensitive to the antiviral effects of 3TC and produced 7-fold less viral DNA than the wild type.

Serum creatine kinase is an unreliable predictor of ectopic pregnancy

OBJECTIVE

To compare serum creatine kinase (CK) values in patients with ectopic pregnancy vs patients with threatened miscarriage or normal pregnancy.

METHODS

An observational case-control study was performed at an urban teaching hospital. Pregnant women with a quantitative beta-hCG obtained for suspicion of ectopic pregnancy were evaluated. Excluded were cases with recent trauma, i.m. injections, surgery, or history of heart, liver, or muscle disease. The serum beta-hCG and CK values were recorded and compared between groups with 1-way ANOVA and Tukey's multiple comparison procedure at the overall 0.05 level.

RESULTS

The 15 ectopic, 28 threatened miscarriage, and 21 normal pregnancy cases were of similar gestational ages (p = 0.2), ranging from 3 to 12 weeks. Although the CK values for ectopic pregnancy (88.8 +/- 33.6 IU/L) exceeded those for threatened miscarriage (65.9 +/- 59.0 IU/L) and normal pregnancy (56.0 +/- 38.1 U/L) (p = 0.02), there was significant overlap between groups. CK values were at or above a cutoff of 74 IU/L in 80% (95% confidence interval: 52-96%) of ectopic pregnancies, 25% (11-45%) of threatened miscarriages, and 14% (3-36%) of normal pregnancies.

CONCLUSIONS

Although the ectopic pregnancy population is characterized by a higher mean CK than are patients with threatened miscarriage or a normal pregnancy, a significant overlap in CK values makes use of this serum marker unreliable for detecting ectopic pregnancy.

Fields and currents in the organs of the human body when exposed to power lines and VLF transmitters

A study is made of the electric fields and currents induced in the organs of the human body when exposed to high-voltage 50-60-Hz transmission lines and 10-30-kHz high-power transmitters. Relevant analyses previously carried out are summarized and supplemented with detailed investigations that complete the picture. Incomplete, misleading, and incorrect statements and methods in the related literature are pointed out, completed, and corrected. The major contribution is to provide quantitatively accurate, relatively simple analytic formulas that relate the incident electric field to the induced field in the organs of the body. The formulation and solution of the underlying integral equation are carried out in the Appendix.

Identification of a cullin homology region in a subunit of the anaphase-promoting complex

The anaphase-promoting complex is composed of eight protein subunits, including BimE (APC1), CDC27 (APC3), CDC16 (APC6), and CDC23 (APC8). The remaining four human APC subunits, APC2, APC4, APC5, and APC7, as well as human CDC23, were cloned. APC7 contains multiple copies of the tetratrico peptide repeat, similar to CDC16, CDC23, and CDC27. Whereas APC4 and APC5 share no similarity to proteins of known function, APC2 contains a region that is similar to a sequence in cullins, a family of proteins implicated in the ubiquitination of G1 phase cyclins and cyclin-dependent kinase inhibitors. The APC2 gene is essential in Saccharomyces cerevisiae, and apc2 mutants arrest at metaphase and are defective in the degradation of Pds1p. APC2 and cullins may be distantly related members of a ubiquitin ligase family that targets cell cycle regulators for degradation.

The hepatitis B virus M539V polymerase variation responsible for 3TC resistance also confers cross-resistance to other nucleoside analogues

A variant of hepatitis B virus (HBV) containing a Met-to-Val substitution (M539V) in the YMDD motif of the polymerase nucleoside-binding domain exhibited resistance to the cytosine analogue lamivudine (3TC). To determine if the mutation responsible for the M539V polymerase variant affected the sensitivity of the virus to other nucleoside analogues, we constructed a tetracycline-responsive cell line, HepAD79. This cell line is stably transfected with a cDNA copy of the pregenomic RNA of an HBV genome containing an A-to-G mutation in the first position of the polymerase gene codon 539. This mutation results in a Met-to-Val substitution at amino acid 539 of the polymerase. When grown under the proper conditions, HepAD79 cells produced HBV RNA, contained HBV DNA associated with immature core particles and released core-associated HBV DNA into the medium. The M539V polymerase variant produced in this cell line was approximately 26-fold less sensitive to the antiviral effects of 3TC than wild-type virus. In addition, this variant demonstrated decreased sensitivity to the cytosine analogues FTC and ddC, as well as the thymidine analogue AZT.

Inducible expression of human hepatitis B virus (HBV) in stably transfected hepatoblastoma cells: a novel system for screening potential inhibitors of HBV replication

We report the development and isolation of a cell line, termed HepAD38, that replicates human hepatitis B virus (HBV) under conditions that can be regulated with tetracycline. In the presence of the antibiotic, this cell line is free of virus due to the repression of pregenomic (pg) RNA synthesis. Upon removal of tetracycline from the culture medium, the cells express viral pg RNA, accumulate subviral particles in the cytoplasm that contain DNA intermediates characteristic of viral replication, and secrete virus-like particles into the supernatant. Since the HepAD38 cell line can produce high levels of HBV DNA, it should be useful for analyses of the viral replication cycle that depend upon viral DNA synthesis in a synchronized fashion. In addition, this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.