Access to long-lived room temperature phosphorescence through auration of 2,1,3-benzothiadiazole

A series of 2,1,3-benzothiadiazole-Au(I)-L complexes have been synthesised, structurally characterised and investigated for their photophysical properties. These are the first organometallic Au(I) complexes containing a C-Au bond on the highly electron-deficient benzothiadiazole unit. The complexes exhibit solution-phase phosphorescence at room temperature, assigned to the intrinsic triplet state of the benzothiadiazole unit that is efficently populated through its attachment to gold. Comparison with routinely reported Au(I) complexes, which include intervening alkenyl linkers, suggests that previous assignments of their phosphorescence as 1π → π*(CCR) might be incomplete. Our observations affirm that, in addition to the heavy atom effect, breaking symmetry in the involved aryl motif may be of importance in controlling the luminescence properties.

High-Valent Ni and Cu Complexes of a Tetraanionic Bis(amidateanilido) Ligand

High-valent metal species are often invoked as intermediates during enzymatic and synthetic catalytic cycles. Anionic donors are often required to stabilize such high-valent states by forming strong bonds with the Lewis acidic metal centers while decreasing their oxidation potentials. In this report, we discuss the synthesis of two high-valent metal complexes [ML]+ in which the NiIII and CuIII centers are ligated by a new tetradentate, tetraanionic bis(amidateanilido) ligand. [ML]+, obtained via chemical oxidation of ML, exhibits UV-vis-NIR, EPR, and XANES spectra characteristic of square planar, high-valent MIII species, suggesting the locus of oxidation for both [ML]+ is predominantly metal-based. This is supported by theoretical analyses, which also support the observed visible transitions as ligand-to-metal charge transfer transitions characteristic of square planar, high-valent MIII species. Notably, [ML]+ can also be obtained via O2 oxidation of ML due to its remarkably negative oxidation potentials (CuL/[CuL]+: -1.16 V, NiL/[NiL]+: -1.01 V vs Fc/Fc+ in MeCN). This demonstrates the exceptionally strong donating nature of the tetraanionic bis(amidateanilido) ligation and its ability to stabilize high-valent metal centers..

NiII and CuII complexes of a salen ligand bearing ferrocenes in its secondary coordination sphere

Herein, we report the synthesis, spectroscopic characterization and electrochemical investigation of the Ni^II and Cu^II complexes of a novel Sal ligand bearing two ferrocene moieties attached at its diimine linker, M(Sal)^Fc. The electronic spectra of M(Sal)^Fc are near identical to its phenyl-substituted counterpart, M(Sal)^Ph, indicating the ferrocene moieties exist in the secondary coordination sphere of M(Sal)^Fc. The cyclic voltammograms of M(Sal)^Fc exhibit an additional two-electron wave in comparison to M(Sal)^Ph, which is assigned to the sequential oxidation of the two ferrocene moieties. The chemical oxidation of M(Sal)^Fc, monitored by low temperature UV-vis spectroscopy, supports the formation of a mixed valent Fe^IIFe^III species followed by a bis(ferrocenium) species upon sequential addition of one and two equivalents of chemical oxidant. The addition of a third equivalent of oxidant to Ni(Sal)^Fc yielded intense near-IR transitions that are indicative of the formation of a fully delocalized Sal-ligand radical (Sal˙), while the same addition to Cu(Sal)^Fc yielded a species that is currently under further spectroscopic investigation. These results suggest the oxidation of the ferrocene moieties of M(Sal)^Fc does not affect the electronic structure of the M(Sal) core, and these are thus in the secondary coordination sphere of the overall complex.

Indolylbenzothiadiazoles as highly tunable fluorophores for imaging lipid droplet accumulation in astrocytes and glioblastoma cells

We present an extensive photophysical study of a series of fluorescent indolylbenzothiadiazole derivatives and their ability to specifically image lipid droplets in astrocytes and glioblastoma cells. All compounds in the series displayed positive solvatochromism together with large Stokes shifts, and π-extended derivatives exhibited elevated brightness. It was shown that the fluorescence properties were highly tunable by varying the electronic character or size of the N-substituent on the indole motif. Three compounds proved capable as probes for detecting small quantities of lipid deposits in healthy and cancerous brain cells. In addition, all twelve compounds in the series were predicted to cross the blood–brain barrier, which raises the prospect for future in vivo studies for exploring the role of lipid droplets in the central nervous system.

We present an extensive photophysical study of a series of fluorescent indolylbenzothiadiazole derivatives and their ability to specifically image lipid droplets in astrocytes and glioblastoma cells.

Determinants of child resilience in poverty: findings from the Taiwan Birth Cohort Study

Background

Poverty has adverse effects on child health. While children in poverty face greater health challenges, some still achieve positive health outcomes. This is in part due to their resilience when facing adversity. Identifying the factors that foster child resilience can aid in developing strategies to promote child resilience and reduce the harmful effects of child poverty. This study aims to identify the biological and social factors of resilience among children in poverty from birth to age 12.

Methods

Data for the analysis came from the Taiwan Birth Cohort Study, a nationally representative sample of 17,354 children who completed six waves of interview surveys between 2005 and 2017. Our sample included 4,570 children who experienced poverty from birth to age 12. The primary outcome variable was child resilience, defined as impoverished children who maintained good health outcomes over the 12-year survey period. Multiple logistic regression was used to examine the factors of child resilience.

Results

Of the 4,570 children, 36.1% always had good health despite experiencing poverty before the age of 12. An easy temperament (OR = 2.5, 95% CI: 1.9-3.0), female (OR = 1.1, 95% CI: 1.0-1.3), a birth weight greater than 2,500 grams (OR = 1.6, 95% CI: 1.2-2.1), having a foreign-born mother (OR = 1.5, 95% CI: 1.2-1.7), receiving breast milk after birth (OR = 1.3, 95% CI: 1.1-1.5), and good parent-child interaction at 3 years of age (OR = 1.4, 95% CI: 1.2-1.7) were associated with child resilience. Early parent-child interactions can moderate the effect of children's birth weight on later resilience.

Conclusions

Our findings indicated the factors associated with child resilience in the context of poverty, suggesting that supporting breastfeeding and nurturing parent-child relationships are effective public health actions to foster child resilience. Future research is needed to unravel the underlying mechanisms of biological factors associated with child resilience.

Key messages

Breastfeeding after birth and high-quality parent-child interaction can lead to positive adaptations to child poverty. Children with difficult temperaments, boys and those born at low birthweight are more vulnerable to poverty and should be targeted for building resilience against poverty.

Resource implications of the latent tuberculosis cascade of care: a time and motion study in five countries

BACKGROUND

The End TB Strategy calls for global scale-up of preventive treatment for latent tuberculosis infection (LTBI), but little information is available about the associated human resource requirements. Our study aimed to quantify the healthcare worker (HCW) time needed to perform the tasks associated with each step along the LTBI cascade of care for household contacts of TB patients.

METHODS

We conducted a time and motion (TAM) study between January 2018 and March 2019, in which consenting HCWs were observed throughout a typical workday. The precise time spent was recorded in pre-specified categories of work activities for each step along the cascade. A linear mixed model was fit to estimate the time at each step.

RESULTS

A total of 173 HCWs in Benin, Canada, Ghana, Indonesia, and Vietnam participated. The greatest amount of time was spent for the medical evaluation (median: 11 min; IQR: 6-16), while the least time was spent on reading a tuberculin skin test (TST) (median: 4 min; IQR: 2-9). The greatest variability was seen in the time spent for each medical evaluation, while TST placement and reading showed the least variability. The total time required to complete all steps along the LTBI cascade, from identification of household contacts (HHC) through to treatment initiation ranged from 1.8 h per index TB patient in Vietnam to 5.2 h in Ghana.

CONCLUSIONS

Our findings suggest that the time requirements are very modest to perform each step in the latent TB cascade of care, but to achieve full identification and management of all household contacts will require additional human resources in many settings.

Exclusive imidazole ligation to CuIII2O2 and CuIIICuII2O2 cores

Direct oxygenation of imidazole-ligated Cu(i) generates dinuclear and trinuclear Cu(iii) species with exclusive imidazole ligation.

Stabilization of different redox levels of a tridentate benzoxazole amidophenoxide ligand when bound to Co(iii) or V(v)

The electronic structure of Co and V complexes of a tridentate benzoxazole-containing aminophenol ligand NNOH2 were characterized by both experimental and theoretical methods.

Electronic Structure and Reactivity Studies of a Nonsymmetric One-Electron Oxidized CuII Bis-phenoxide Complex

The tetradentate mixed imino/amino phenoxide ligand (N-(3,5-di-tert-butylsalicylidene)-N'-(2-hydroxyl-3,5-di-tert-butylbenzyl))-trans-1,2-cyclohexanediamine (salalen) was complexed with CuII, and the resulting Cu complex (2) was characterized by a number of experimental techniques and theoretical calculations. Two quasi-reversible redox processes for 2, as observed by cyclic voltammetry, demonstrated the potential stability of oxidized forms, and also the increased electron-donating ability of the salalen ligand in comparison to the salen analogue. The electronic structure of the one-electron oxidized [2]+ was then studied in detail, and Cu K-edge X-ray Absorption Spectroscopy (XAS) measurements confirmed a CuII-phenoxyl radical complex in solution. Subsequent resonance Raman (rR) and variable temperature 1H NMR studies, coupled with theoretical calculations, showed that [2• ]+ is a triplet (S = 1) CuII-phenoxyl radical species, with localization of the radical on the more electron-rich aminophenoxide. Attempted isolation of X-ray quality crystals of [2• ]+ afforded [2H]+, with a protonated phenol bonded to CuII, and an additional H-bonding interaction with the SbF6 - counterion. Stoichiometric reaction of dilute solutions of [2• ]+ with benzyl alcohol showed that the complex reacted in a similar manner as the oxidized CuII-salen analogue, and does not exhibit a substrate-binding pre-equilibrium as observed for the oxidized bisaminophenoxide CuII-salan derivative.

Octahedral Co(III) salen complexes: the role of peripheral ligand electronics on axial ligand release upon reduction

A series of octahedral CoIII salen complexes (where salen represents a N2O2 bis-Schiff-base bis-phenolate framework) were prepared with axial imidazole ligating groups. When using 1-methylimidazole (1-MeIm) axial ligands, the CoIII/CoII reduction potential could be altered by 220 mV via variation of the electron-donating ability of the para-ring substituents (R = H (1), OMe (2), tBu (3), Br (4), NO2 (5), and CF3 (6)). In addition, the irreversibility of the reduction process suggested substantial geometrical changes and axial ligand exchange upon reduction to the more labile CoII oxidation state. Installing an imidazole-coumarin conjugate as the axial ligands resulted in fluorescence quenching when bound to the CoIII centre (R = H (7), OMe (8), and CF3 (9)). The redox properties and fluorescence increase upon ligand release for 7–9 were studied under reducing conditions and in the presence of excess competing ligand (1-MeIm). It was determined that the Lewis acidity of the CoIII centre was the dominant factor in controlling axial ligand exchange for this series of complexes.

The structure of a one-electron oxidized Mn(iii)-bis(phenolate)dipyrrin radical complex and oxidation catalysis control via ligand-centered redox activity

The tetradentate ligand dppH3, which features a half-porphyrin and two electron-rich phenol moieties, was prepared and chelated to manganese. The mononuclear Mn(iii)-dipyrrophenolate complex 1 was structurally characterized. The metal ion lies in a square pyramidal environment, the apical position being occupied by a methanol molecule. Complex 1 displays two reversible oxidation waves at 0.00 V and 0.47 V vs. Fc⁺/Fc, which are assigned to ligand-centered processes. The one-electron oxidized species 1+ SbF6- was crystallized, showing an octahedral Mn(iii) center with two water molecules coordinated at both apical positions. The bond distance analysis and DFT calculations disclose that the radical is delocalized over the whole aromatic framework. Complex 1+ SbF6- exhibits an S_tot = 3/2 spin state due to the antiferromagnetic coupling between Mn(iii) and the ligand radical. The zero field splitting parameters are D = 1.6 cm^-1, E/D = 0.18(1), g_⊥ = 1.99 and g_∥ = 1.98. The dication 12+ is an integer spin system, which is assigned to a doubly oxidized ligand coordinated to a Mn(iii) metal center. Both 1 and 1+ SbF6- catalyze styrene oxidation in the presence of PhIO, but the nature of the main reaction product is different. Styrene oxide is the main reaction product when using 1, but phenylacetaldehyde is formed predominantly when using 1+ SbF6-. We examined the ability of complex 1+ SbF6- to catalyze the isomerization of styrene oxide and found that it is an efficient catalyst for the anti-Markovnikov opening of styrene oxide. The formation of phenylacetaldehyde from styrene therefore proceeds in a tandem E-I (epoxidation-isomerization) mechanism in the case of 1+ SbF6-. This is the first evidence of control of the reactivity for styrene oxidation by changing the oxidation state of a catalyst based on a redox-active ligand.

Peritherapeutic Hemodynamic Changes of Carotid Stenting Evaluated with Quantitative DSA in Patients with Carotid Stenosis

BACKGROUND AND PURPOSE

Quantitative data from DSA have become important tools for understanding hemodynamic changes of intracranial lesions. In this study, we evaluated 8 hemodynamic parameters in patients before and after carotid artery angioplasty.

MATERIALS AND METHODS

DSA images of 34 patients with carotid stenosis who underwent angioplasty and stent placement were retrospectively analyzed. Eleven ROIs (M1, M2, A1, A2, the parietal vein, superior sagittal sinus, internal jugular vein, and 4 in the ICA) were selected on color-coded DSA. Eight hemodynamic parameters (bolus arrival time, TTP, relative TTP, full width at half maximum, wash-in slope, washout slope, maximum enhancement, and area under the curve) were measured from the time-concentration curves of these ROIs. The dependent t test for paired samples was applied to these parameters before and after stent placement.

RESULTS

We found that the treatment significantly reduced TTP, relative TTP, bolus arrival time, and washout slope at all arterial ROIs and full width at half maximum and area under the curve at some arterial ROIs. Bolus arrival time was significantly reduced after treatment for all arterial ROIs, the parietal vein, and the superior sagittal sinus. The maximum enhancement and wash-in slope did not show significant changes after treatment. After treatment, the relative TTP from the ICA to M1, M2, and the parietal vein returned to normal values.

CONCLUSIONS

In addition to TTP and relative TTP, other parameters can be used to evaluate peritherapeutic cerebral hemodynamic changes. Bolus arrival time has the potential to evaluate brain circulation at arterial and venous sites, especially when TTP cannot be measured because of an incomplete time-concentration curve.

Simplest Monodentate Imidazole Stabilization of the oxy-Tyrosinase Cu2 O2 Core: Phenolate Hydroxylation through a Cu(III) Intermediate

Tyrosinases are ubiquitous binuclear copper enzymes that oxygenate to Cu(II) 2 O2 cores bonded by three histidine Nτ-imidazoles per Cu center. Synthetic monodentate imidazole-bonded Cu(II) 2 O2 species self-assemble in a near quantitative manner at -125 °C, but Nπ-ligation has been required. Herein, we disclose the syntheses and reactivity of three Nτ-imidazole bonded Cu(II) 2 O2 species at solution temperatures of -145 °C, which was achieved using a eutectic mixture of THF and 2-MeTHF. The addition of anionic phenolates affords a Cu(III) 2 O2 species, where the bonded phenolates hydroxylate to catecholates in high yields. Similar Cu(III) 2 O2 intermediates are not observed using Nπ-bonded Cu(II) 2 O2 species, hinting that Nτ-imidazole ligation, conserved in all characterized Ty, has functional advantage beyond active-site flexibility. Substrate accessibility to the oxygenated Cu2 O2 core and stabilization of a high oxidation state of the copper centers are suggested from these minimalistic models.

Synthesis and electronic structure determination of uranium(vi) ligand radical complexes

Pentagonal bipyramidal uranyl (UO₂²⁺) complexes of salen ligands were prepared and the electronic structure of the one-electron oxidized species[1a–c]+were investigated in solution.

Tuning ligand electronics and peripheral substitution on cobalt salen complexes: structure and polymerisation activity

A series of cobalt salen complexes, where salen represents an N2O2 bis-Schiff-base bis-phenolate framework, are prepared, characterised and investigated for reversible-termination organometallic mediated radical polymerisation (RT-OMRP). The salen ligands contain a cyclohexane diimine bridge and systematically altered para-substituted phenoxide moieties as a method to examine the electronic impact of the ligand on complex structure and reactivity. The complexes are characterised by single crystal X-ray diffraction, cyclic voltammetry, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy and computational methods. Structural studies all support a tailorable metal centre reactivity altered by the electron-donating ability of the salen ligand. RT-OMRP of styrene, methyl methacrylate and vinyl acetate is reported and suggests that cobalt-carbon bond strength varies with the ligand substitution. Competing β-hydrogen abstraction affords long-chain olefin-terminated polymer chains and well controlled vinyl acetate polymerisations, contrasting with the lower temperature associative exchange mechanism of degenerative transfer OMRP.

Influence of ligand flexibility on the electronic structure of oxidized Ni(III)-phenoxide complexes

One-electron-oxidized Ni(III)-phenoxide complexes with salen-type ligands, [Ni(salen)py2](2+) ([1(en)-py](2+)) and [Ni(1,2-salcn)py2](2+) ([1(cn)-py](2+)), with a five-membered chelate dinitrogen backbone and [Ni(salpn)py2](2+) ([2(pn)-py](2+)), with a six-membered chelate backbone, have been characterized with a combination of experimental and theoretical methods. The five-membered chelate complexes [1(en)-py](2+) and [1(cn)-py](2+) were assigned as Ni(III)-phenoxyl radical species, while the six-membered chelate complex [2(pn)-py](2+) was concluded to be a Ni(II)-bis(phenoxyl radical) species with metal-centered reduction in the course of the one-electron oxidation of the Ni(III)-phenoxide complex [2(pn)-py](+). Thus, the oxidation state of the one-electron-oxidized Ni(III) salen-type complexes depends on the chelate ring size of the dinitrogen backbone.

Ligand-centered redox activity in cobalt(II) and nickel(II) bis(phenolate)-dipyrrin complexes

One for all: a trianionic ligand containing the biologically relevant moieties phenolate and porphyrin was designed and synthesized. One-electron oxidation of the nickel and cobalt complexes of these ligands affords an unprecedented and highly stable hybrid porphyrinyl-phenoxyl radical bound to the metal center. Two-electron oxidation of these complexes leads to the M(2+) -(close-shell two-electron oxidized ligand) species.

Dually incontinent nursing home residents: clinical characteristics and treatment differences

OBJECTIVE

Previous studies have described urinary and fecal incontinence in nursing homes and their separate effects on healthcare utilization. However, little is known about those who are incontinent of both.

DESIGN

Retrospective chart review.

SETTINGS

Twenty sites in three states

PARTICIPANTS

A total of 413 nursing home residents were categorized as having neither fecal nor urinary incontinence (C, n = 114), urinary incontinence only (UI, n = 53), fecal incontinence only (FI, n = 9), or were dually incontinent (DI, n = 237).

MEASUREMENTS

Charts were abstracted for sociodemographic information and health status information as well as utilization for the year before the date of abstraction. We then compared these characteristics across groups using ANOVA with pairwise comparisons and multiply adjusted regression.

RESULTS

Almost all patients with DI were cognitively and mobility impaired. However, there were no significant differences between the groups with respect to age and number of diagnoses. A diagnosis of stroke was also more common among those with DI compared with C. When examining healthcare utilization in multiply adjusted regression, dually incontinent residents received significantly fewer days of hospital care than those with UI.

CONCLUSIONS

Dual incontinence in NH residents is likely to have an important functional component. These residents seem to be treated less aggressively with respect to hospitalization compared with those with UI alone. The reasons for these differences need to be explored further.

Predictors of medication prescription in nursing homes

OBJECTIVES

To identify patient characteristics associated with higher numbers of prescribed drugs or risk of receiving one or more inappropriate medications.

DESIGN

A cross-sectional survey using chart reviews.

PARTICIPANTS

A total of 414 long-stay residents of 20 nursing homes in three states

MEASUREMENTS

Current medication orders, sociodemographic information, and diagnoses and health status information as indicated by the MDS. The number of routine, total, and inappropriate medications were tabulated.

RESULTS

Higher numbers of medications were associated with higher total numbers of diseases. In addition, several diseases (congestive heart failure, hypertension, depression, anxiety, and diabetes) were associated with higher numbers of medications even after controlling for total disease burden. Cognitive impairment was associated with fewer medications after controlling for total number of diseases. Advanced age also attenuated the effect of disease burden on the number of total and routine medications. The only independent predictor of more inappropriate medications was higher numbers of routine medications.

CONCLUSION

Several specific disease states predispose patients to prescription of higher numbers of medication, and, these patients must be managed more carefully to prevent adverse drug-drug or drug-disease interactions. Why patients with compromised cognitive status receive fewer medications requires further study.

Targeting of U2AF65 to sites of active splicing in the nucleus

U2AF65 is an essential splicing factor that promotes binding of U2 small nuclear (sn)RNP at the pre-mRNA branchpoint. Here we describe a novel monoclonal antibody that reacts specifically with U2AF65. Using this antibody, we show that U2AF65 is diffusely distributed in the nucleoplasm with additional concentration in nuclear speckles, which represent subnuclear compartments enriched in splicing snRNPs and other splicing factors. Furthermore, transient expression assays using epitope-tagged deletion mutants of U2AF65 indicate that targeting of the protein to nuclear speckles is not affected by removing either the RNA binding domain, the RS domain, or the region required for interaction with U2AF35. The association of U2AF65 with speckles persists during mitosis, when transcription and splicing are downregulated. Moreover, U2AF65 is localized to nuclear speckles in early G1 cells that were treated with transcription inhibitors during mitosis, suggesting that the localization of U2AF65 in speckles is independent of the presence of pre-mRNA in the nucleus, which is consistent with the idea that speckles represent storage sites for inactive splicing factors. After adenovirus infection, U2AF65 redistributes from the speckles and is prefferentially detected at sites of viral transcription. By combining adenoviral infection with transient expression of deletion mutants, we show a specific requirement of the RS domain for recruitment of U2AF65 to sites of active splicing in the nucleus. This suggests that interactions involving the RS region of U2AF65 may play an important role in targeting this protein to spliceosomes in vivo.

Translational control of programmed cell death: eukaryotic translation initiation factor 4E blocks apoptosis in growth-factor-restricted fibroblasts with physiologically expressed or deregulated Myc

There is increasing evidence that cell cycle transit is potentially lethal, with survival depending on the activation of metabolic pathways which block apoptosis. However, the identities of those pathways coupling cell cycle transit to survival remain undefined. Here we show that the eukaryotic translation initiation factor 4E (eIF4E) can mediate both proliferative and survival signaling. Overexpression of eIF4E completely substituted for serum or individual growth factors in preserving the viability of established NIH 3T3 fibroblasts. An eIF4E mutant (Ser-53 changed to Ala) defective in mediating its growth-factor-regulated functions was also defective in its survival signaling. Survival signaling by enforced expression of eIF4E did not result from autocrine release of survival factors, nor did it lead to increased expression of the apoptosis antagonists Bcl-2 and Bcl-XL. In addition, the execution apparatus of the apoptotic response in eIF4E-overexpressing cells was found to be intact. Increased expression of eIF4E was sufficient to inhibit apoptosis in serum-restricted primary fibroblasts with enforced expression of Myc. In contrast, activation of Ha-Ras, which is required for eIF4E proliferative signaling, did not suppress Myc-induced apoptosis. These data suggest that the eIF4E-activated pathways leading to survival and cell cycle progression are distinct. This dual signaling of proliferation and survival might be the basis for the potency of eIF4E as an inducer of neoplastic transformation.

Efficient random subcloning of DNA sheared in a recirculating point-sink flow system

Based on a high-performance liquid chromatographic pump, we have built a device that allows recirculation of DNA through a 63-microm orifice with ensuing fractionation to a minimum fragment size of approximately 300 base pairs. Residence time of the DNA fragments in the converging flow created by a sudden contraction was found to be sufficiently long to allow extension of the DNA molecules into a highly extended conformation and, hence, breakage to occur at midpoint. In most instances, 30 passages sufficed to obtain a narrow size distribution, with >90% of the fragments lying within a 2-fold size distribution. The shear rate required to achieve breakage was found to be inversely proportional to the 1.0 power of the molecular weight. Compared with a restriction digest, up to 40% of all fragments could be cloned directly, with only marginal improvements in cloning efficiency having been observed upon prior end repair with Klenow, T4 polymerase or T4 polynucleotide kinase. Sequencing revealed a fairly random distribution of the fragments.

Analysis of trans-dominant mutants of the HIV type 1 Rev protein for their ability to inhibit Rev function, HIV type 1 replication, and their use as anti-HIV gene therapeutics

The HIV-1 rev gene product facilitates the transport of singly spliced and unspliced HIV-1 transcripts and is necessary for productive HIV-1 infection. On the basis of the previously described trans-dominant Rev mutant M10, four point mutants and one frameshift mutant of the Rev protein were constructed. The mutants were inserted into retroviral expression vectors and analyzed for their ability to inhibit Rev-mediated gene expression. Transient transfection systems were used to screen these new mutants, and each was shown to inhibit expression of a Rev-dependent CAT reporter plasmid. Inhibition of HIV-1 envelope gene expression was tested in the HeLa-T4 cell line and was also shown to be inhibited by the trans-dominant Rev mutants. Retroviral vector producer cell lines were constructed and used to transduce Rev trans-dominant genes into the human T-cell line SupT1. The engineered SupT1 cell lines were then challenged with HIV-1 IIIB and HIV-1 expression was monitored by Northern blot analysis and in situ hybridization. SupT1 cells expressing either a Rev point mutant or the frameshift mutant showed greatly reduced HIV-1 mRNA accumulation and the Rev-dependent singly spliced and unspliced HIV-1 mRNAs were reduced. The kinetics of viral replication following challenge of Rev trans-dominant-engineered SupT1 cells with both HIV-1 IIIB and MN strains was significantly reduced and cells were protected from viral lysis. Viruses that emerge late in infection from Rev trans-dominant-engineered cultures are not resistant to Rev-mediated inhibition. Last, trans-dominant Rev-mediated protection of human CD4+ lymphocytes from challenge with primary HIV-1 patient isolates confirms the potential utility of this system as an anti-HIV-1 gene therapy approach.

Inhibition of clinical human immunodeficiency virus (HIV) type 1 isolates in primary CD4+ T lymphocytes by retroviral vectors expressing anti-HIV genes

Gene therapy may be of benefit in human immunodeficiency virus type 1 (HIV-1)-infected individuals by virtue of its ability to inhibit virus replication and prevent viral gene expression. It is not known whether anti-HIV-1 gene therapy strategies based on antisense or transdominant HIV-1 mutant proteins can inhibit the replication and expression of clinical HIV-1 isolates in primary CD4+ T lymphocytes. We therefore transduced CD4+ T lymphocytes from uninfected individuals with retroviral vectors expressing either HIV-1-specific antisense-TAR or antisense-Tat/Rev RNA, transdominant HIV-1 Rev protein, and a combination of antisense-TAR and transdominant Rev. The engineered CD4+ T lymphocytes were then infected with four different clinical HIV-1 isolates. We found that replication of all HIV-1 isolates was inhibited by all the anti-HIV vectors tested. Greater inhibition of HIV-1 was observed with transdominant Rev than with antisense RNA. We hereby demonstrated effective protection by antisense RNA or transdominant mutant proteins against HIV-1 infection in primary CD4+ T lymphocytes using clinical HIV-1 isolates, and this represents an essential step toward clinical anti-HIV-1 gene therapy.

Macrophage production of basic fibroblast growth factor in the fibroproliferative disorder of alveolar fibrosis after lung injury

In organ repair following injury, macrophages accumulate and granulation tissue, comprised of fibroblasts and endothelial cells, develops in the injured area. Basic fibroblast growth factor (bFGF), a potent stimulator of fibroblast and endothelial cell growth, has been linked to the fibroproliferative process. Macrophages are thought to play a central role in the fibroproliferative response, and prior studies indicate that they produce bFGF. Whereas it is plausible that macrophages produce bFGF in a fibroproliferative process, currently no data exists that directly identifies the macrophage as a source of bFGF in a fibroproliferative disorder. We used the model of acute intraalveolar granulation tissue formation following lung injury to determine if the macrophage was a cellular source of bFGF in a naturally occurring fibroproliferative process. To examine this hypothesis, patients with severe acute lung injury underwent bronchoalveolar lavage during the phase of lung repair. Polymerase chain reaction and Northern analysis of macrophage RNA revealed the presence of two species of bFGF messenger RNA (4.4 kb and 1.9 kb). Metabolic labeling studies of recovered macrophages revealed a newly synthesized 18-kd protein with antigenic similarity to bFGF. Immunohistochemical evaluation of lung tissue from patients who died following acute lung injury, showed numerous bFGF immunoreactive macrophages present within airspaces containing fibroblastic and vascular tissue proliferation. This investigation has identified the alveolar macrophage as a cellular source of bFGF in the fibroproliferative disorder of intraalveolar fibrosis following acute lung injury.