High dimensional predictions of suicide risk in 4.2 million US Veterans using ensemble transfer learning

We present an ensemble transfer learning method to predict suicide from Veterans Affairs (VA) electronic medical records (EMR). A diverse set of base models was trained to predict a binary outcome constructed from reported suicide, suicide attempt, and overdose diagnoses with varying choices of study design and prediction methodology. Each model used twenty cross-sectional and 190 longitudinal variables observed in eight time intervals covering 7.5 years prior to the time of prediction. Ensembles of seven base models were created and fine-tuned with ten variables expected to change with study design and outcome definition in order to predict suicide and combined outcome in a prospective cohort. The ensemble models achieved c-statistics of 0.73 on 2-year suicide risk and 0.83 on the combined outcome when predicting on a prospective cohort of [Formula: see text] 4.2 M veterans. The ensembles rely on nonlinear base models trained using a matched retrospective nested case-control (Rcc) study cohort and show good calibration across a diversity of subgroups, including risk strata, age, sex, race, and level of healthcare utilization. In addition, a linear Rcc base model provided a rich set of biological predictors, including indicators of suicide, substance use disorder, mental health diagnoses and treatments, hypoxia and vascular damage, and demographics.

Identification of Novel, Replicable Genetic Risk Loci for Suicidal Thoughts and Behaviors Among US Military Veterans

Importance

Suicide is a leading cause of death; however, the molecular genetic basis of suicidal thoughts and behaviors (SITB) remains unknown.

Objective

To identify novel, replicable genomic risk loci for SITB.

Design, Setting, and Participants

This genome-wide association study included 633 778 US military veterans with and without SITB, as identified through electronic health records. GWAS was performed separately by ancestry, controlling for sex, age, and genetic substructure. Cross-ancestry risk loci were identified through meta-analysis. Study enrollment began in 2011 and is ongoing. Data were analyzed from November 2021 to August 2022.

Main Outcome and Measures

SITB.

Results

A total of 633 778 US military veterans were included in the analysis (57 152 [9%] female; 121 118 [19.1%] African ancestry, 8285 [1.3%] Asian ancestry, 452 767 [71.4%] European ancestry, and 51 608 [8.1%] Hispanic ancestry), including 121 211 individuals with SITB (19.1%). Meta-analysis identified more than 200 GWS (P < 5 × 10-8) cross-ancestry risk single-nucleotide variants for SITB concentrated in 7 regions on chromosomes 2, 6, 9, 11, 14, 16, and 18. Top single-nucleotide variants were largely intronic in nature; 5 were independently replicated in ISGC, including rs6557168 in ESR1, rs12808482 in DRD2, rs77641763 in EXD3, rs10671545 in DCC, and rs36006172 in TRAF3. Associations for FBXL19 and AC018880.2 were not replicated. Gene-based analyses implicated 24 additional GWS cross-ancestry risk genes, including FURIN, TSNARE1, and the NCAM1-TTC12-ANKK1-DRD2 gene cluster. Cross-ancestry enrichment analyses revealed significant enrichment for expression in brain and pituitary tissue, synapse and ubiquitination processes, amphetamine addiction, parathyroid hormone synthesis, axon guidance, and dopaminergic pathways. Seven other unique European ancestry-specific GWS loci were identified, 2 of which (POM121L2 and METTL15/LINC02758) were replicated. Two additional GWS ancestry-specific loci were identified within the African ancestry (PET112/GATB) and Hispanic ancestry (intergenic locus on chromosome 4) subsets, both of which were replicated. No GWS loci were identified within the Asian ancestry subset; however, significant enrichment was observed for axon guidance, cyclic adenosine monophosphate signaling, focal adhesion, glutamatergic synapse, and oxytocin signaling pathways across all ancestries. Within the European ancestry subset, genetic correlations (r > 0.75) were observed between the SITB phenotype and a suicide attempt-only phenotype, depression, and posttraumatic stress disorder. Additionally, polygenic risk score analyses revealed that the Million Veteran Program polygenic risk score had nominally significant main effects in 2 independent samples of veterans of European and African ancestry.

Conclusions and Relevance

The findings of this analysis may advance understanding of the molecular genetic basis of SITB and provide evidence for ESR1, DRD2, TRAF3, and DCC as cross-ancestry candidate risk genes. More work is needed to replicate these findings and to determine if and how these genes might impact clinical care.

OrganiCam: a lightweight time-resolved laser-induced luminescence imager and Raman spectrometer for planetary organic material characterization

OrganiCam is a laser-induced luminescence imager and spectrometer designed for standoff organic and biosignature detection on planetary bodies. OrganiCam uses a diffused laser beam (12° cone) to cover a large area at several meters distance and records luminescence on half of its intensified detector. The diffuser can be removed to record Raman and fluorescence spectra from a small spot from 2 m standoff distance. OrganiCam's small size and light weight makes it ideal for surveying organics on planetary surfaces. We have designed and built a brassboard version of the OrganiCam instrument and performed initial tests of the system.

Single-trial cross-area neural population dynamics during long-term skill learning

Mammalian cortex has both local and cross-area connections, suggesting vital roles for both local and cross-area neural population dynamics in cortically-dependent tasks, like movement learning. Prior studies of movement learning have focused on how single-area population dynamics change during short-term adaptation. It is unclear how cross-area dynamics contribute to movement learning, particularly long-term learning and skill acquisition. Using simultaneous recordings of rodent motor (M1) and premotor (M2) cortex and computational methods, we show how cross-area activity patterns evolve during reach-to-grasp learning in rats. The emergence of reach-related modulation in cross-area activity correlates with skill acquisition, and single-trial modulation in cross-area activity predicts reaction time and reach duration. Local M2 neural activity precedes local M1 activity, supporting top-down hierarchy between the regions. M2 inactivation preferentially affects cross-area dynamics and behavior, with minimal disruption of local M1 dynamics. Together, these results indicate that cross-area population dynamics are necessary for learned motor skills.

PKC-η-MARCKS Signaling Promotes Intracellular Survival of Unopsonized Burkholderia thailandensis

Pathogenic Burkholderia rely on host factors for efficient intracellular replication and are highly refractory to antibiotic treatment. To identify host genes that are required by Burkholderia spp. during infection, we performed a RNA interference (RNAi) screen of the human kinome and identified 35 host kinases that facilitated Burkholderia thailandensis intracellular survival in human monocytic THP-1 cells. We validated a selection of host kinases using imaging flow cytometry to assess efficiency of B. thailandensis survival in the host upon siRNA-mediated knockdown. We focused on the role of the novel protein kinase C isoform, PKC-η, in Burkholderia infection and characterized PKC-η/MARCKS signaling as a key event that promotes the survival of unopsonized B. thailandensis CDC2721121 within host cells. While infection of lung epithelial cells with unopsonized Gram-negative bacteria stimulated phosphorylation of Ser175/160 in the MARCKS effector domain, siRNA-mediated knockdown of PKC-η expression reduced the levels of phosphorylated MARCKS by >3-fold in response to infection with Bt CDC2721121. We compared the effect of the conventional PKC-α and novel PKC-η isoforms on the growth of B. thailandensis CDC2721121 within monocytic THP-1 cells and found that ≥75% knock-down of PRKCH transcript levels reduced intracellular bacterial load 100% more efficiently when compared to growth in cells siRNA-depleted of the classical PKC-α, suggesting that the PKC-η isoform can specifically mediate Burkholderia intracellular survival. Based on imaging studies of intracellular B. thailandensis, we found that PKC-η function stimulates phagocytic pathways that promote B. thailandensis escape into the cytoplasm leading to activation of autophagosome flux. Identification of host kinases that are targeted by Burkholderia during infection provides valuable molecular insights in understanding Burkholderia pathogenesis, and ultimately, in designing effective host-targeted therapies against infectious disease caused by intracellular pathogens.

The interplay between chromosome stability and cell cycle control explored through gene-gene interaction and computational simulation

Chromosome stability models are usually qualitative models derived from molecular-genetic mechanisms for DNA repair, DNA synthesis, and cell division. While qualitative models are informative, they are also challenging to reformulate as precise quantitative models. In this report we explore how (A) laboratory experiments, (B) quantitative simulation, and (C) seriation algorithms can inform models of chromosome stability. Laboratory experiments were used to identify 19 genes that when over-expressed cause chromosome instability in the yeast Saccharomyces cerevisiae To better understand the molecular mechanisms by which these genes act, we explored their genetic interactions with 18 deletion mutations known to cause chromosome instability. Quantitative simulations based on a mathematical model of the cell cycle were used to predict the consequences of several genetic interactions. These simulations lead us to suspect that the chromosome instability genes cause cell-cycle perturbations. Cell-cycle involvement was confirmed using a seriation algorithm, which was used to analyze the genetic interaction matrix to reveal an underlying cyclical pattern. The seriation algorithm searched over 10(14) possible arrangements of rows and columns to find one optimal arrangement, which correctly reflects events during cell cycle phases. To conclude, we illustrate how the molecular mechanisms behind these cell cycle events are consistent with established molecular interaction maps.

In silico analyses of missense mutations in coagulation factor VIII: identification of severity determinants of haemophilia A

Factor VIII (FVIII) mutations cause haemophilia A (HA), an X-linked recessive coagulation disorder. Over 1000 missense mutations in FVIII are known and they lead to variable clinical phenotypes (severe, moderate and mild). The exact molecular basis of this phenotypic heterogeneity by FVIII missense mutations is elusive to date. In this study, we aimed to identify the severity determinants that cause phenotypic heterogeneity of HA. We compiled and curated a data set of 766 missense mutations from the repertoire of missense mutations in FVIII. We analysed these mutations by computational programs (e.g. Swiss-PdbViewer) and different mutation analysis servers (e.g. SIFT, PROVEAN, CUPSAT, PolyPhen2, MutPred); and various sequence- and structure-based parameters were assessed for any significant distribution bias among different HA phenotypes. Our analyses suggest that 'mutations in evolutionary conserved residues', 'mutations in buried residues', mutation-induced 'steric clash' and 'surface electrostatic potential alteration' act as risk factors towards severe HA. We have developed a grading system for FVIII mutations combining the severity determinants, and the grading pattern correlates with HA phenotype. This study will help to correctly associate the HA phenotype with a mutation and aid early characterization of novel variants.

Multi-drug resistance efflux pumps confer additional resistance against host innate immune defense via induction of genes for biofilm formation and virulence (MPF3P.803)

Multi-drug resistance, resistance-nodulation-differentiation efflux pumps in gram-negative bacteria are membrane protein complexes that extrude a wide variety of drugs before they can act on their bacterial target. However, they are not merely pumps for physical transport of drugs but their expression level is also up-regulated by the presence of drugs inside the bacteria, which, in turn, facilitates the release of quorum-sensing molecules and subsequent induction of genes responsible for biofilm formation and virulence. It is our hypothesis that efflux mediated biofilm formation and virulence expression offer gram-negative bacteria additional resistance not only against drugs but also against host innate immune defense. In order to test our hypothesis, we performed real-time qPCR studies on Fluidigm platform to monitor the expression of (i) the efflux genes and their regulators, (ii) the genes for synthesis of quorum sensing molecules and their regulators, and (iii) the genes for biofilm formation and virulence. For this, we used Pseudomonas aeruginosa and its efflux and quorum sensing mutants. The gene expression studies were performed for planktonic cells and nascent and mature biofilms in the presence and absence of a drug, ciprofloxacin. We were able to show efflux mediated expression of biofilm and virulence genes, which resulted in the abrogation of host innate immune defense in a cellular assay.

A new protein-protein interaction sensor based on tripartite split-GFP association

Monitoring protein-protein interactions in living cells is key to unraveling their roles in numerous cellular processes and various diseases. Previously described split-GFP based sensors suffer from poor folding and/or self-assembly background fluorescence. Here, we have engineered a micro-tagging system to monitor protein-protein interactions in vivo and in vitro. The assay is based on tripartite association between two twenty amino-acids long GFP tags, GFP10 and GFP11, fused to interacting protein partners, and the complementary GFP1-9 detector. When proteins interact, GFP10 and GFP11 self-associate with GFP1-9 to reconstitute a functional GFP. Using coiled-coils and FRB/FKBP12 model systems we characterize the sensor in vitro and in Escherichia coli. We extend the studies to mammalian cells and examine the FK-506 inhibition of the rapamycin-induced association of FRB/FKBP12. The small size of these tags and their minimal effect on fusion protein behavior and solubility should enable new experiments for monitoring protein-protein association by fluorescence.

Targeted In Situ Biosynthetic Transcriptional Activation in Native Surface-Level Human Articular Chondrocytes during Lesion Stabilization

OBJECTIVE

Safe articular cartilage lesion stabilization is an important early surgical intervention advance toward mitigating articular cartilage disease burden. While short-term chondrocyte viability and chondrosupportive matrix modification have been demonstrated within tissue contiguous to targeted removal of damaged articular cartilage, longer term tissue responses require evaluation to further clarify treatment efficacy. The purpose of this study was to examine surface chondrocyte responses within contiguous tissue after lesion stabilization.

METHODS

Nonablation radiofrequency lesion stabilization of human cartilage explants obtained during knee replacement was performed for surface fibrillation. Time-dependent chondrocyte viability, nuclear morphology and cell distribution, and temporal response kinetics of matrix and chaperone gene transcription indicative of differentiated chondrocyte function were evaluated in samples at intervals to 96 hours after treatment.

RESULTS

Subadjacent surface articular cartilage chondrocytes demonstrated continued viability for 96 hours after treatment, a lack of increased nuclear fragmentation or condensation, persistent nucleic acid production during incubation reflecting cellular assembly behavior, and transcriptional up-regulation of matrix and chaperone genes indicative of retained biosynthetic differentiated cell function.

CONCLUSIONS

The results of this study provide further evidence of treatment efficacy and suggest the possibility to manipulate or induce cellular function, thereby recruiting local chondrocytes to aid lesion recovery. Early surgical intervention may be viewed as a tissue rescue, allowing articular cartilage to continue displaying biological responses appropriate to its function rather than converting to a tissue ultimately governed by the degenerative material property responses of matrix failure. Early intervention may positively impact the late changes and reduce disease burden of damaged articular cartilage.

The Brucella TIR-like protein TcpB interacts with the death domain of MyD88

The pathogen Brucella melitensis secretes a Toll/interleukin-1 receptor (TIR) domain containing protein that abrogates host innate immune responses. In this study, we have characterized the biochemical interactions of Brucella TIR-like protein TcpB with host innate immune adaptor proteins. Using protein-fragment complementation assays based on Gaussia luciferase and green fluorescent protein, we find that TcpB interacts directly with MyD88 and that this interaction is significantly stronger than the interaction of TcpB with TIRAP, the only other adaptor protein that detectably interacts with TcpB. Surprisingly, the TcpB-MyD88 interaction depends on the death domain (DD) of MyD88, and TcpB does not interact with the isolated TIR domain of MyD88. TcpB disrupts MyD88(DD)-MyD88(DD), MyD88(DD)-MyD88(TIR) and MyD88(DD)-MyD88 interactions but not MyD88-MyD88 or MyD88(TIR)-MyD88(TIR) interactions. Structural models consistent with these results suggest how TcpB might inhibit TLR signaling by targeting MyD88 via a DD-TIR domain interface.

Native Chondrocyte Viability during Cartilage Lesion Progression: Normal to Surface Fibrillation

OBJECTIVE

Early surgical intervention for articular cartilage disease is desirable before full-thickness lesions develop. As early intervention treatments are designed, native chondrocyte viability at the treatment site before intervention becomes an important parameter to consider. The purpose of this study is to evaluate native chondrocyte viability in a series of specimens demonstrating the progression of articular cartilage lesions to determine if the chondrocyte viability profile changes during the evolution of articular cartilage disease to the level of surface fibrillation.

DESIGN

Osteochondral specimens demonstrating various degrees of articular cartilage damage were obtained from patients undergoing knee total joint replacement. Three groups were created within a patient harvest based on visual and tactile cues commonly encountered during surgical intervention: group 1, visually and tactilely intact surfaces; group 2, visually intact, tactilely soft surfaces; and group 3, surface fibrillation. Confocal laser microscopy was performed following live/dead cell viability staining.

RESULTS

Groups 1 to 3 demonstrated viable chondrocytes in all specimens, even within the fibrillated portions of articular cartilage, with little to no evidence of dead chondrocytes. Chondrocyte viability profile in articular cartilage does not appear to change as disease lesion progresses from normal to surface fibrillation.

CONCLUSIONS

Fibrillated partial-thickness articular cartilage lesions are a good therapeutic target for early intervention. These lesions retain a high profile of viable chondrocytes and are readily diagnosed by visual and tactile cues during surgery. Early intervention should be based on matrix failure rather than on more aggressive procedures that further corrupt the matrix and contribute to chondrocyte necrosis of contiguous untargeted cartilage.

Histopomorphic evaluation of radiofrequency mediated débridement chondroplasty

The use of radiofrequency devices has become widespread for surgical ablation procedures. When ablation devices have been deployed in treatment settings requiring tissue preservation like débridement chondroplasty, adoption has been limited due to the collateral damage caused by these devices in healthy tissue surrounding the treatment site. Ex vivo radiofrequency mediated débridement chondroplasty was performed on osteochondral specimens demonstrating surface fibrillation obtained from patients undergoing knee total joint replacement. Three radiofrequency systems designed to perform débridement chondroplasty were tested each demonstrating different energy delivery methods: monopolar ablation, bipolar ablation, and non-ablation energy. Treatment outcomes were compared with control specimens as to clinical endpoint and histopomorphic characteristics. Fibrillated cartilage was removed in all specimens; however, the residual tissue remaining at the treatment site displayed significantly different characteristics attributable to radiofrequency energy delivery method. Systems that delivered ablation-based energies caused tissue necrosis and collateral damage at the treatment site including corruption of cartilage Superficial and Transitional Zones; whereas, the non-ablation system created a smooth articular surface with Superficial Zone maintenance and without chondrocyte death or tissue necrosis. The mechanism of radiofrequency energy deposition upon tissues is particularly important in treatment settings requiring tissue preservation. Ablation-based device systems can cause a worsened state of articular cartilage from that of pre-treatment. Non-ablation energy can be successful in modifying/preconditioning tissue during débridement chondroplasty without causing collateral damage. Utilizing a non-ablation radiofrequency system provides the ability to perform successful débridement chondroplasty without causing additional articular cartilage tissue damage and may allow for other cartilage intervention success.

Signaling, delivery and age as emerging issues in the benefit/risk ratio outcome of tPA For treatment of CNS ischemic disorders

Stroke is a leading cause of morbidity and mortality. While tissue-type plasminogen activator (tPA) remains the only FDA-approved treatment for ischemic stroke, clinical use of tPA has been constrained to roughly 3% of eligible patients because of the danger of intracranial hemorrhage and a narrow 3 h time window for safe administration. Basic science studies indicate that tPA enhances excitotoxic neuronal cell death. In this review, the beneficial and deleterious effects of tPA in ischemic brain are discussed along with emphasis on development of new approaches toward treatment of patients with acute ischemic stroke. In particular, roles of tPA-induced signaling and a novel delivery system for tPA administration based on tPA coupling to carrier red blood cells will be considered as therapeutic modalities for increasing tPA benefit/risk ratio. The concept of the neurovascular unit will be discussed in the context of dynamic relationships between tPA-induced changes in cerebral hemodynamics and histopathologic outcome of CNS ischemia. Additionally, the role of age will be considered since thrombolytic therapy is being increasingly used in the pediatric population, but there are few basic science studies of CNS injury in pediatric animals.

Erythrocyte-bound tissue plasminogen activator is neuroprotective in experimental traumatic brain injury

The purpose of this study was to test the effects of exogenous tissue plasminogen activator (tPA) in traumatic brain injury (TBI).We tested two different tPA formulations, free tPA and tPA bound to erythrocytes (RBC/tPA).Vehicle and each of the tPA treatments were injected intravenously into anesthetized rats 15 min after moderate lateral fluid percussion injury. The animals were sacrificed at 2 days for calculating microclot burden (n=13) and IgG staining area (n=13) in the brain sections as indicators of post-traumatic thrombosis and blood-brain barrier (BBB) breakdown, respectively. Another set of injured animals treated in the same way were sacrificed at 7 days to compare cortical lesion volumes (n=28) and CA3 hippocampal cell loss (n=24). All evaluations were done blinded with respect to treatment. No significant differences were found with respect to microclot burden or IgG staining volume. Injection of wild-type tPA caused significantly ( p<0.05) larger cortical injuries and greater cerebral hemorrhage. In contrast, there was significantly less cortical injury ( p<0.01) and hippocampal cell loss ( p<0.01) in the RBC=tPA group than in all other groups. These results reveal that RBC/tPA is more neuroprotective in experimental TBI than is unbound tPA.

Beryllium alters lipopolysaccharide-mediated intracellular phosphorylation and cytokine release in human peripheral blood mononuclear cells

Beryllium exposure in susceptible individuals leads to the development of chronic beryllium disease, a lung disorder marked by release of inflammatory cytokine and granuloma formation. We have previously reported that beryllium induces an immune response even in blood mononuclear cells from healthy individuals. In this study, we investigate the effects of beryllium on lipopolysaccharide-mediated cytokine release in blood mononuclear and dendritic cells from healthy individuals. We found that in vitro treatment of beryllium sulfate inhibits the secretion of lipopolysaccharide-mediated interleukin 10, while the release of interleukin 1beta is enhanced. In addition, not all lipopolysaccharide-mediated responses are altered, as interleukin 6 release in unaffected upon beryllium treatment. Beryllium sulfate-treated cells show altered phosphotyrosine levels upon lipopolysaccharide stimulation. Significantly, beryllium inhibits the phosphorylation of signal transducer and activator of transducer 3, induced by lipopolysaccharide. Finally, inhibitors of phosphoinositide-3 kinase mimic the effects of beryllium in inhibition of interleukin 10 release, while they have no effect on interleukin 1beta secretion. This study strongly suggests that prior exposures to beryllium could alter host immune responses to bacterial infections in healthy individuals, by altering intracellular signaling.

Red blood cells-coupled tPA prevents impairment of cerebral vasodilatory responses and tissue injury in pediatric cerebral hypoxia/ischemia through inhibition of ERK MAPK activation

Babies experience hypoxia (H) and ischemia (I) from stroke. The only approved treatment for stroke is fibrinolytic therapy with tissue-type plasminogen activator (tPA). However, tPA potentiates H/I-induced impairment of responses to cerebrovasodilators such as hypercapnia and hypotension, and blockade of tPA-mediated vasoactivity prevents this deleterious effect. Coupling of tPA to red blood cells (RBCs) reduces its central nervous system (CNS) toxicity through spatially confining the drug to the vasculature. Mitogen-activated protein kinase (MAPK), a family of at least three kinases, is upregulated after H/I. In this study we determined whether RBC-tPA given before or after cerebral H/I would preserve responses to cerebrovasodilators and prevent neuronal injury mediated through the extracellular signal-related kinase (ERK) MAPK pathway. Animals given RBC-tPA maintained responses to cerebrovasodilators at levels equivalent to pre-H/I values. cerebrospinal fluid and brain parenchymal ERK MAPK was elevated by H/I and this upregulation was potentiated by tPA, but blunted by RBC-tPA. U0126, an ERK MAPK antagonist, also maintained cerebrovasodilation post H/I. Neuronal degeneration in CA1 hippocampus after H/I was not improved by tPA, but was ameliorated by RBC-tPA and U0126. These data suggest that coupling of tPA to RBCs offers a novel approach toward increasing the benefit/risk ratio of thrombolytic therapy for CNS disorders associated with H/I.

Cerebrovascular thromboprophylaxis in mice by erythrocyte-coupled tissue-type plasminogen activator

BACKGROUND

Cerebrovascular thrombosis is a major source of morbidity and mortality after surgery, but thromboprophylaxis in this setting is limited because of the formidable risk of perioperative bleeding. Thrombolytics (eg, tissue-type plasminogen activator [tPA]) cannot be used prophylactically in this high-risk setting because of their short duration of action and risk of causing hemorrhage and central nervous system damage. We found that coupling tPA to carrier red blood cells (RBCs) prolongs and localizes tPA activity within the bloodstream and converts it into a thromboprophylactic agent, RBC/tPA. To evaluate the utility of this new approach for preventing cerebrovascular thrombosis, we examined the effect of RBC/tPA in animal models of cerebrovascular thromboembolism and ischemia.

METHODS AND RESULTS

Preformed fibrin microemboli were injected into the middle carotid artery of mice, occluding downstream perfusion and causing severe infarction and 50% mortality within 48 hours. Preinjected RBC/tPA rapidly lysed nascent cerebral thromboemboli, providing rapid, durable reperfusion and reducing morbidity and mortality. These beneficial effects were not achieved by preinjection of tPA, even at a 10-fold higher dose, which increased mortality from 50% to 90% by 10 hours after embolization. RBC/tPA injected 10 minutes after tail amputation to simulate postsurgical hemostasis did not cause bleeding from the wound, whereas soluble tPA caused profuse bleeding. RBC/tPA neither aggravated brain damage caused by focal ischemia in a filament model of middle carotid artery occlusion nor caused postthrombotic hemorrhage in hypertensive rats.

CONCLUSIONS

These results suggest a potential RBC/tPA utility as thromboprophylaxis in patients who are at risk for acute cerebrovascular thromboembolism.

Association studies of lung function in mice

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide and an accelerating decline of lung function is the earliest and a major indicator of the onset of COPD. Therefore it has become necessary to understand the genetic basis of this complex physiological trait in order to determine the potential susceptibility factors of this disease. REINHARD et al (2005) performed the genome wide linkage analysis study with inbred mice having extremely divergent lung function (C3H/HeJ versus JF1/Msf) and identified multiple Quantitative Trait Loci (QTLs) on mouse chromosomes (mCh) 5, 15, 17, and 19 with Logarithm of odd (LOD) scores > or = 4. Significant linkages to total lung capacity (TLC) were detected on mCh 15 and 17, to dead space volume (VD) and lung compliance (C(L)) on mCh 5 and 15, to C(L) on mCh 19, and to diffusing capacity for CO (D(co)) on mCh 15 and 17. Several of the mouse chromosomal regions identified were syntenic to human chromosomal regions identified with linkage to FEV1 (forced expiratory volume-1 second), FVC (forced vital capacity), or FEV1/FVC in separate studies. Using a systematic approach of expression QTL (e-QTL) strategy and exon-wise sequencing of suggested candidate genes followed by predicted protein structure and property, GANGULY et al (2007) recently proposed four candidate genes for lung function in mice. They are superoxide dismutase 3, extracellular [SOD3; mCh 5: V(D)], trefoil factor 2 (TFF2; mCh 17: TLC and D(co)), ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2; mCh 15:TLC and C(L)), and relaxin 1 (RLN1; mCh 19; CL and CL/TLC). As a part of functional validation, gene-targeted Sod3-/- mice were detected with increased conducting airway volume (V(D)/TLC) compared with strain-matched control Sod3+/+ mice, consistent with the QTL on mCh 5. Findings with gene-targeted mice suggested that SOD3 is a contributing factor defining the complex trait of conducting airway volume. The human variation in these genes needs further study both in lung development and in the development of lung disease as a part of translational approach.

The glycocalyx protects erythrocyte-bound tissue-type plasminogen activator from enzymatic inhibition

Coupling tissue-type plasminogen activator (tPA) to carrier red blood cells (RBC) prolongs its intravascular life span and permits its use for thromboprophylaxis. Here, we studied the susceptibility of RBC/tPA to PA inhibitors including plasminogen activator inhibitor-1 (PAI-1) that constrain its activity and may reduce the duration of its effect. Despite lesser spatial and diffusional limitations, soluble tPA was far less effective than RBC/tPA in dissolving clots formed in vitro from blood of wild-type (WT) mice (40 versus 80% lysis at equal doses of tPA). Furthermore, after i.v. injection, soluble tPA lost activity faster in transgenic mice expressing a high level of PAI-1 than in WT mice, whereas the activity of RBC/tPA was unaffected. PAI-1 inactivated soluble tPA at equimolar ratios in vitro, but it had no effect on the amidolytic or fibrinolytic activity of RBC/tPA. RBC/tPA was also more resistant than soluble tPA to in vitro inhibition by other serpins (alpha2-macroglobulin and alpha1-antitrypsin) and pathologically high levels of glucose. However, coupling to RBC did not protect a truncated tPA mutant, Retavase, from plasma inhibitors. Chemical removal of the RBC glycocalyx negated tPA protection from inhibitors: tPA coupled to glycocalyx-stripped RBC bound twice as much 125I-PAI-1 as did tPA coupled to naive RBC, and susceptibility of the bound tPA to inhibition by PAI-1 was restored. Thus, the RBC glycocalyx protects RBC-coupled tPA against inhibition. Resistance to high levels of inhibitors in vivo contributes to the potential utility of RBC/tPA for thromboprophylaxis.

Human complement receptor type 1-directed loading of tissue plasminogen activator on circulating erythrocytes for prophylactic fibrinolysis

Plasminogen activators (PAs) are not used for thromboprophylaxis due to rapid clearance, bleeding, and extravascular toxicity. We describe a novel strategy that overcomes these limitations. We conjugated tissue-type PA (tPA) to a monoclonal antibody (mAb) against complement receptor type 1 (CR1) expressed primarily on human RBCs. Anti-CR1/tPA conjugate, but not control conjugate (mIgG/tPA), bound to human RBCs (1.2 x 10(3) tPA molecules/cell at saturation), endowing them with fibrinolytic activity. In vitro, RBC-bound anti-CR1/tPA caused 90% clot lysis versus 20% by naive RBCs. In vivo, more than 40% of anti-CR1/(125)I-tPA remained within the circulation ( approximately 90% bound to RBCs) 3 hours after injection in transgenic mice expressing human CR1 (TgN-hCR1) versus less than 10% in wild-type (WT) mice, without RBC damage; approximately 90% of mIgG/(125)I-tPA was cleared from the circulation within 30 minutes in both WT and TgN-hCR1 mice. Anti-CR1/tPA accelerated lysis of pulmonary emboli and prevented stable occlusive carotid arterial thrombi from forming after injection in TgN-hCR1 mice, but not in WT mice, whereas soluble tPA and mIgG/tPA were ineffective. Anti-CR1/tPA caused 20-fold less rebleeding in TgN-hCR1 mice than the same dose of tPA. CR1-directed immunotargeting of PAs to circulating RBCs provides a safe and practical means to deliver fibrinolytics for thromboprophylaxis in settings characterized by a high imminent risk of thrombosis.

Pronounced inhibitory effect of chlorcyclizine (CCZ) in experimental hepatocarcinoma

Thepiperazine chlorcyclizine HCl (CCZ), possessing significant antimetabolic as well as virucidal and virustatic activities against the human immunodeficiency virus (HIV) and other retroviruses, was selected to determine its anticarcinogenic potential The anticancer activity of CCZ was evaluated against procarcinogen n-diethylnitrosamine (NDA)-initiated hepatocarcinogenesis, which was subsequently promoted by phenobarbital (PB) in male Sprague-Dawley rats. The anticancer efficacy of CCZ was monitored by estimating some potential markers of neoplastic and preneoplastic hepatic conditions, e.g., glutathione (GSH), glutathione-S-transferase (GST) and gamma-glutamyl transpeptidase (gammaGTP). CCZ exhibited antineoplastic activity on a long-term therapeutic basis. Furthermore, this drug restricted the exponential increase of the antioxidant markers in the hyperplastic nodule and the surrounding liver tissues in comparison with the carcinogen-controlled rats during the entire period of treatment. A decrease in the number of nodules was observed in the CCZ-treated group.

Fibrin Affinity of Erythrocyte-Coupled Tissue-Type Plasminogen Activators Endures Hemodynamic Forces and Enhances Fibrinolysis in Vivo

Plasminogen activators (PAs; e.g., tissue-type, tPA) coupled to red blood cells (RBCs) display in vivo features useful for thromboprophylaxis: prolonged circulation, minimal extravasation, and preferential lysis of nascent versus preexisting clots. Yet, factors controlling the activity of RBC-bound PAs in vivo are not defined and may not mirror the profile of soluble PAs. We tested the role of RBC/PA binding to fibrin in fibrinolysis. RBC/tPA and RBC/tPA variant with low fibrin affinity (rPA) bound to and lysed plasminogen-containing fibrin clots in vitro comparably. In contrast, when coinjected in mice with fibrin emboli lodging in pulmonary vasculature, only RBC/tPA accumulated in lungs, which resulted in a more extensive fibrinolysis versus RBC/rPA (p < 0.01). Reconciling this apparent divergence between in vitro and in vivo behaviors, RBC/tPA, but not RBC/rPA perfused over fibrin in vitro at physiological shear stress bound to fibrin clots and caused greater fibrinolysis versus RBC/rPA (p < 0.001). These results indicate that because of high fibrin affinity, RBC/tPA binding to clots endures hemodynamic stress, which enhances fibrinolysis. Behavior of RBC/PAs under hemodynamic pressure is an important predictor of their performance in vivo.

Endothelial targeting of a recombinant construct fusing a PECAM-1 single-chain variable antibody fragment (scFv) with prourokinase facilitates prophylactic thrombolysis in the pulmonary vasculature

Means to prevent thrombus extension and local recurrence remain suboptimal, in part because of the limited effectiveness of existing thrombolytics. In theory, plasminogen activators could be used for this purpose if they could be anchored to the vascular lumen by targeting stably expressed, noninternalized determinants such as platelet-endothelial-cell adhesion molecule 1 (PECAM-1). We designed a recombinant molecule fusing low-molecular-weight single-chain prourokinase plasminogen activator (lmw-scuPA) with a single-chain variable fragment (scFv) of a PECAM-1 antibody to generate the prodrug scFv/lmw-scuPA. Cleavage by plasmin generated fibrinolytically active 2-chain lmw-uPA. This fusion protein (1) bound specifically to PECAM-1-expressing cells; (2) was rapidly cleared from blood after intravenous injection; (3) accumulated in the lungs of wild-type C57BL6/J, but not PECAM-1 null mice; and (4) lysed pulmonary emboli formed subsequently more effectively than lmw-scuPA, thereby providing support for the concept of thromboprophylaxis using recombinant scFv-fibrinolytic fusion proteins that target endothelium.

Blood Clearance and Activity of Erythrocyte-Coupled Fibrinolytics

Conjugating tissue-type plasminogen activator (tPA) to red blood cells (RBCs) endows it with features useful for thromboprophylaxis. However, the optimal intensity and duration of thromboprophylaxis vary among clinical settings. To assess how the intrinsic properties of a plasminogen activator (PA) affect functions of the corresponding RBC/PA conjugate, we coupled equal amounts of tPA or Retavase (rPA; a variant with an extended circulation time, lower fibrin affinity, and greater susceptibility to PA inhibitors). Conjugation to RBC markedly prolonged the circulation of each PA in rats and mice, without detrimental effects on carrier RBC. The initial blood clearance of RBC/tPA was faster than RBC/rPA, yet it exerted greater fibrinolytic activity, in part due to greater resistance of tPA and RBC/tPA to plasma inhibitors versus rPA and RBC/rPA observed in vitro. Soluble and RBC-coupled tPA and rPA exerted the same amidolytic activity, yet RBC/tPA lysed fibrin clots more effectively than RBC/rPA, notwithstanding comparable fibrinolytic activity of their soluble counterparts. Conjugation to RBC suppressed rPA's ability to be activated by fibrin, whereas the fibrin activation of RBC-coupled tPA was not hindered. Therefore, the functional profile of RBC/PA is influenced by: pharmacokinetic features provided by carrier RBC (e.g., prolonged circulation), intrinsic PA features (e.g., clearance rate, resistance to inhibitors), and changes imposed by conjugation to RBC (e.g., loss of cofactor stimulation). These factors, different from those guiding the design of soluble PA for lysis of existing clots, can be exploited in the rational design of RBC/PA tailored for specific prophylactic indications.

Triflupromazine: a microbicide non-antibiotic compound

The antipsychotic phenothiazine triflupromazine, possessing a methyl-thio substituent at position 10 and a fluorine moiety at position 2, exhibited significant antibacterial activity against 279 strains of Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) of the drug, according to the agar dilution method, was between 2 and 50 microg/ml for Staphylococcus aureus, and 5 and 100 microg/ml for shigellae and vibrios. Triflupromazine, when injected intraperitoneally into Swiss albino mice at a concentration of 30 microg/mouse (20 g), manifested a significant protection to the mice (p<0.001) when they were challenged with 50 median lethal dose (MLD) of Salmonella typhimurium NCTC 74. Moreover, there was a statistically significant reduction in the number of viable bacteria in organ homogenates and blood of mice treated with this phenothiazine compound.

Antimicrobial potentiality of a new non-antibiotic: the cardiovascular drug oxyfedrine hydrochloride

Ten cardiovascular drugs, having diverse pharmacological action, were screened for possible antimicrobial property against known eight sensitive bacteria, belonging to Gram positive and Gram negative types. Although five drugs failed to show antimicrobial activity and three had moderate antimicrobial action, oxyfedrine HCl and dobutamine were seen to possess pronounced antimicrobial property. Oxyfedrine was further tested in vitro against 471 strains of bacteria from two Gram positive and fourteen Gram negative genera. The minimum inhibitory concentration (MIC) of oxyfedrine was determined by agar dilution method, which ranged from 50-200 microg/ml in most of the strains, while some strains were inhibited at even lower concentrations. In animal experiments, this compound was capable of offering significant protection to Swiss strain of white mice, challenged with 50 median lethal dose (MLD) of a virulent strain of Salmonella typhimurium at concentrations of 15, 30 and 60 microg/mouse. The in vivo results were highly significant according to chi-square test.

Amlodipine: a cardiovascular drug with powerful antimicrobial property

Ten cardiovascular drugs were procured in pure form from their manufacturers in India and screened for antimicrobial property against fifteen known bacteria belonging to both gram-positive and gram-negative types. These bacteria were inhibited by the common antibiotics at 1-5 mg ml(-1) level through our earlier studies. Since most of the bacteria were moderate to highly responsive to amlodipine, this compound was further tested in vitro against 504 bacteria comprising 4 genera of gram-positive and 15 genera of gram-negative bacteria. Most of these were inhibited by the drug at 50-200 microg ml(-1) level and few strains were sensitive even at lower concentrations (10 microg ml(-1)). The bacteria could be arranged in the decreasing order of sensitivity towards amlodipine in the following manner: Staphylococcus aureus, Vibrio cholerae, Vibrio parahemolyticus, Shigella spp., Salmonella spp., Bacillus spp., whereas Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa were found to be resistant to the lower concentrations of the drug. Amlodipine was found to be bactericidal in nature when its mode of action was studied against S. aureus 6571, V. cholerae 14035 and Sh boydii 8 NCTC 254/66. The antibacterial activity of amlodipine could also be confirmed in vivo. When it was given to Swiss strain of white mice at different dosages (30 and 60 microg/mouse), it could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to Chi square test the in vivo data were highly significant (p<0.001).

Antimicrobial activity of prenylflavanones

Among two flavanones [YS01, YS02] and eight prenylflavanones [YS03-YS10], preliminary screening with fifteen test bacterial strains showed that YS06 was the most active agent. YS06 exhibited highly significant antimicrobial action when tested against 228 bacterial strains comprising two Gram-positive and six Gram-negative genera. The in vitro susceptibility test was carried out by determining the minimum inhibitory concentration (MIC) of YS06 by agar dilution technique. Twenty-two out of fifty strains of Staphylococcus aureus were inhibited at 25 to 50 micrograms/mL of the agent. YS06 also inhibited strains of Salmonella, Shigella and a few strains of Escherichia coli strains were also highly sensitive to YS06, while Kleibsiella spp. and Pseudomonas aeruginosa were much less sensitive. In in vivo study, YS06 offered significant protection (p < 0.001 according to chi-square test) to Swiss albino mice (challenged with 50 minimum lethal dose (MLD, virulent bacterium) at concentrations of 160 and 80 micrograms/mouse.