Publications by authors named "Mirabela Hali"

12 Publications

  • Page 1 of 1

Postmortem neuroimaging: Temporal and spatial sensitivity of manganese-enhanced magnetic resonance imaging (MEMRI) and impact of Mn uptake.

Hear Res 2021 May 24;407:108276. Epub 2021 May 24.

Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA; John D. Dingell VAMC, Detroit, MI, USA. Electronic address:

Magnetic resonance imaging data collection and analysis have been challenges in the field of auditory neuroscience. Recent studies have addressed these concerns by using manganese-enhanced magnetic resonance imaging (MEMRI). Basic challenges for in vivo application of MEMRI in rodents includes how to set inclusion criteria for adequate Mn uptake and whether valid data can be collected from brains postmortem. Since brain Mn uptake is complete within 2-4 h and clearance can take 2-4 weeks, one assumption has been that Mn-enhanced R1 values continue to reliably reflect the degree of Mn-uptake for some indeterminate time after death. To address these issues, the impact of death on R1 values was determined in rats administered Mn and rats that were not. Images of auditory nuclei were collected at fixed intervals from rats before and after death for up to 10 h postmortem. By taking a ratio of pituitary and muscle T1-W intensities (P/M), a reliable quantitative method for assessing adequate brain Mn uptake was created and suggest that P/M ratios should be adopted to objectively measure the quality of the Mn injection. Postmortem R1 values decreased in all brain regions in both the After Mn and No Mn groups. However, the time-course of postmortem changes in R1 was dependent on brain region and degree of Mn uptake. Thus, postmortem R1 values not only differ after death, but vary with time and across brain regions. Postmortem R1 values in unfixed brain tissue, including the auditory nuclei, should be interpreted with caution.
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http://dx.doi.org/10.1016/j.heares.2021.108276DOI Listing
May 2021

RhoG-Rac1 Signaling Pathway Mediates Metabolic Dysfunction of the Pancreatic Beta-Cells Under Chronic Hyperglycemic Conditions.

Cell Physiol Biochem 2021 Apr;55(2):180-192

Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA,

Background/aims: Published evidence suggests regulatory roles for small G proteins (Cdc42 and Rac1) in glucose-stimulated insulin secretion (GSIS) from pancreatic beta-cells. More recent evidence suggests novel roles for these G proteins, specifically Rac1, in the induction of metabolic dysfunction of the islet beta-cell under the duress of a variety of stress conditions. However, potential upstream regulators of sustained activation of Rac1 have not been identified in the beta-cell. Recent studies in other cell types have identified RhoG, a small G protein, as an upstream regulator of Rac1 under specific experimental conditions. Herein, we examined putative roles for RhoG in islet beta-cell dysregulation induced by glucotoxic conditions.

Methods: Expression of RhoG or GDIγ was suppressed by siRNA transfection using the DharmaFect1 reagent. Subcellular fractions were isolated using NE-PER Nuclear and Cytoplasmic Extraction Reagent kit. The degree of activation of Rac1 was assessed using a pull-down assay kit. Extent of cell death was quantified using a Cell Death Detection ELISA kit.

Results: RhoG is expressed in human islets, rat islets, and clonal INS-1 832/13 cells. siRNA-RhoG markedly attenuated sustained activation of Rac1 and caspase-3 in INS-1 832/13 cells exposed to hyperglycemic conditions (20 mM; 24 hours). In a manner akin to Rac1, which has been shown to translocate to the nuclear fraction to induce beta-cell dysfunction under metabolic stress, a significant increase in the association of RhoG with the nuclear fraction was observed in beta-cells under the duress of metabolic stress. Interestingly, GDIγ, a known regulator of RhoG, remained associated with non-nuclear fraction under conditions RhoG and Rac1 translocated to the membrane. Lastly, siRNA-RhoG modestly attenuated pancreatic beta-cell demise induced by high glucose exposure conditions, but such an effect was not statistically significant.

Conclusion: Based on these data we conclude that RhoG-Rac1 signaling module plays critical regulatory roles in promoting mitochondrial dysfunction (caspase-3 activation) of the islet beta cell under metabolic stress.
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http://dx.doi.org/10.33594/000000354DOI Listing
April 2021

Publisher Correction: Novel QUEST MRI In Vivo Measurement of Noise-induced Oxidative Stress in the Cochlea.

Sci Rep 2019 Dec 27;9(1):20036. Epub 2019 Dec 27.

Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-019-55312-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934791PMC
December 2019

Novel QUEST MRI In Vivo Measurement of Noise-induced Oxidative Stress in the Cochlea.

Sci Rep 2019 11 7;9(1):16265. Epub 2019 Nov 7.

Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA.

Effective personalized therapeutic treatment for hearing loss is currently not available. Cochlear oxidative stress is commonly identified in the pathogenesis of hearing loss based upon findings from excised tissue, thus suggesting a promising druggable etiology. However, the timing and site(s) to target for anti-oxidant treatment in vivo are not clear. Here, we address this long-standing problem with QUEnch-assiSTed Magnetic Resonance Imaging (QUEST MRI), which non-invasively measures excessive production of free radicals without an exogenous contrast agent. QUEST MRI is hypothesized to be sensitive to noise-evoked cochlear oxidative stress in vivo. Rats exposed to a loud noise event that resulted in hair cell loss and reduced hearing capability had a supra-normal MRI R1 value in their cochleae that could be corrected with anti-oxidants, thus non-invasively indicating cochlear oxidative stress. A gold-standard oxidative damage biomarker [heme oxidase 1 (HO-1)] supported the QUEST MRI result. The results from this study highlight QUEST MRI as a potentially transformative measurement of cochlear oxidative stress in vivo that can be used as a biomarker for improving individual evaluation of anti-oxidant treatment efficacy in currently incurable oxidative stress-based forms of hearing loss.
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http://dx.doi.org/10.1038/s41598-019-52439-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6838338PMC
November 2019

MRI compatible MS2 nanoparticles designed to cross the blood-brain-barrier: providing a path towards tinnitus treatment.

Nanomedicine 2018 10 14;14(7):1999-2008. Epub 2018 Apr 14.

Wayne State University School of Medicine, 540 E Canfield St, Detroit, MI, United States; John D. Dingell VA Medical Center, 4646 John R St, Detroit, MI, United States. Electronic address:

Fundamental challenges of targeting specific brain regions for treatment using pharmacotherapeutic nanoparticle (NP) carriers include circumventing the blood-brain-barrier (BBB) and tracking delivery. Angiopep-2 (AP2) has been shown to facilitate the transport of large macromolecules and synthetic nanoparticles across the BBB. Thus, conjugation of AP2 to an MS2 bacteriophage based NP should also permit transport across the BBB. We have fabricated and tested a novel MS2 capsid-based NP conjugated to the ligand AP2. The reaction efficiency was determined to be over 70%, with up to two angiopep-2 conjugated per MS2 capsid protein. When linked with a porphyrin ring, manganese (Mn) remained stable within MS2 and was MRI detectable. Nanoparticles were introduced intracerebroventricularly or systemically. Systemic delivery yielded dose dependent, non-toxic accumulation of NPs in the midbrain. Design of a multifunctional MRI compatible NP platform provides a significant step forward for the diagnosis and treatment of intractable brain conditions, such as tinnitus.
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http://dx.doi.org/10.1016/j.nano.2018.04.003DOI Listing
October 2018

Tinnitus and temporary hearing loss result in differential noise-induced spatial reorganization of brain activity.

Brain Struct Funct 2018 Jun 27;223(5):2343-2360. Epub 2018 Feb 27.

Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA.

Loud noise frequently results in hyperacusis or hearing loss (i.e., increased or decreased sensitivity to sound). These conditions are often accompanied by tinnitus (ringing in the ears) and changes in spontaneous neuronal activity (SNA). The ability to differentiate the contributions of hyperacusis and hearing loss to neural correlates of tinnitus has yet to be achieved. Towards this purpose, we used a combination of behavior, electrophysiology, and imaging tools to investigate two models of noise-induced tinnitus (either with temporary hearing loss or with permanent hearing loss). Manganese (Mn) uptake was used as a measure of calcium channel function and as an index of SNA. Manganese uptake was examined in vivo with manganese-enhanced magnetic resonance imaging (MEMRI) in key auditory brain regions implicated in tinnitus. Following acoustic trauma, MEMRI, the SNA index, showed evidence of spatially dependent rearrangement of Mn uptake within specific brain nuclei (i.e., reorganization). Reorganization of Mn uptake in the superior olivary complex and cochlear nucleus was dependent upon tinnitus status. However, reorganization of Mn uptake in the inferior colliculus was dependent upon hearing sensitivity. Furthermore, following permanent hearing loss, reduced Mn uptake was observed. Overall, by combining testing for hearing sensitivity, tinnitus, and SNA, our data move forward the possibility of discriminating the contributions of hyperacusis and hearing loss to tinnitus.
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http://dx.doi.org/10.1007/s00429-018-1635-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6129978PMC
June 2018

Dendrimer-conjugated peptide vaccine enhances clearance of Chlamydia trachomatis genital infection.

Int J Pharm 2017 Jul 22;527(1-2):79-91. Epub 2017 May 22.

Departments of Immunology and Microbiology, Internal Medicine (Rheumatology), and Ophthalmology, School of Medicine, Wayne State University, Detroit, MI 48201, USA. Electronic address:

Peptide-based vaccines have emerged in recent years as promising candidates in the prevention of infectious diseases. However, there are many challenges to maintaining in vivo peptide stability and enhancement of peptide immunogenicity to generate protective immunity which enhances clearance of infections. Here, a dendrimer-based carrier system is proposed for peptide-based vaccine delivery, and shows its anti-microbial feasibility in a mouse model of Chlamydia trachomatis. Chlamydiae are the most prevalent sexually transmitted bacteria worldwide, and also the causal agent of trachoma, the leading cause of preventable infectious blindness. In spite of the prevalence of this infectious agent and the many previous vaccine-related studies, there is no vaccine commercially available. The carrier system proposed consists of generation 4, hydroxyl-terminated, polyamidoamine (PAMAM) dendrimers (G4OH), to which a peptide mimic of a chlamydial glycolipid antigen-Peptide 4 (Pep4, AFPQFRSATLLL) was conjugated through an ester bond. The ester bond between G4OH and Pep4 is expected to break down mainly in the intracellular environment for antigen presentation. Pep4 conjugated to dendrimer induced Chlamydia-specific serum antibodies after subcutaneous immunizations. Further, this new vaccine formulation significantly protected immunized animals from vaginal challenge with infectious Chlamydia trachomatis, and it reduced infectious loads and tissue (genital tract) damage. Pep4 conjugated to G4OH or only mixed with peptide provided enhanced protection compared to Pep4 and adjuvant (i.e. alum), suggesting a potential adjuvant effect of the PAMAM dendrimer. Combined, these results demonstrate that hydroxyl-terminated PAMAM dendrimer is a promising polymeric nanocarrier platform for the delivery of peptide vaccines and this approach has potential to be expanded to other infectious intracellular bacteria and viruses of public health significance.
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http://dx.doi.org/10.1016/j.ijpharm.2017.05.045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522616PMC
July 2017

Folate-functionalized dendrimers for targeting Chlamydia-infected tissues in a mouse model of reactive arthritis.

Int J Pharm 2014 May 5;466(1-2):258-65. Epub 2014 Mar 5.

Department of Immunology & Microbiology, School of Medicine, Wayne State University, 540 East Canfield Avenue, Detroit, MI 48201, United States. Electronic address:

Chlamydia trachomatis is an intracellular human pathogen that causes a sexually transmitted disease which may result in an inflammatory arthritis designated Chlamydia-induced reactive arthritis (ReA). The arthritis develops after dissemination of infected cells from the initial site of chlamydial infection. During Chlamydia-associated ReA, the organism may enter into a persistent infection state making treatment with antibiotics a challenge. We hypothesize that folate receptors (FR), which are overexpressed in Chlamydia-infected cells, and the associated inflammation would allow folate-targeted nanodevices to better treat infections. To investigate this, we developed a folate-PAMAM dendrimer-Cy5.5 conjugate (D-FA-Cy5.5), where Cy5.5 is used as the near-IR imaging agent. Uptake of D-FA-Cy5.5 upon systemic administration was assessed and compared to non-folate conjugated controls (D-Cy5.5), using a mouse model of Chlamydia-induced ReA, and near-IR imaging. Our results suggested that there was a higher concentration of folate-based nanodevice in sites of infection and inflammation compared to that of the control nanodevice. The folate-conjugated nanodevices localized to infected paws and genital tracts (major sites of inflammation and infection) at 3-4 fold higher concentrations than were dendrimer alone, suggesting that the overexpression of folate receptors in infected and inflamed tissues enables higher dendrimer uptake. There was an increase in uptake into thymus, spleen, and lung, but no significant differences in the uptake of the folate nanodevices in other organs including kidney and heart, indicating the 'relative specificity' of the D-FA-Cy5.5 conjugate nanodevices. These results suggest that folate targeting dendrimers are able to deliver drugs to attenuate infection and associated inflammation in Chlamydia-induced ReA.
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http://dx.doi.org/10.1016/j.ijpharm.2014.03.018DOI Listing
May 2014

Dendrimer-enabled transformation of Chlamydia trachomatis.

Microb Pathog 2013 Dec 25;65:29-35. Epub 2013 Sep 25.

Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21235, USA.

Lack of a system for genetic manipulation of Chlamydia trachomatis has been a key challenge to advancing understanding the molecular genetic basis of virulence for this bacterial pathogen. We developed a non-viral, dendrimer-enabled system for transformation of this organism and used it to characterize the effects of inserting the common 7.5 kbp chlamydial plasmid into strain L2(25667R), a C. trachomatis isolate lacking it. The plasmid was cloned in pUC19 and the clone complexed to polyamidoamine dendrimers, producing ∼83 nm spherical particles. Nearly confluent McCoy cell cultures were infected with L2(25667R) and reference strain L2(434). At 16 h post-infection, medium was replaced with dendrimer-plasmid complexes in medium lacking additives (L2(25667R)) or with additive-free medium alone (L2(434)). Three h later complexes/buffer were removed, and medium was replaced; cultures were harvested at various times post-transformation for analyses. Real time PCR and RT-PCR of nucleic acids from transformed cultures demonstrated plasmid replication and gene expression. A previous report indicated that one or more plasmid-encoded product govern(s) transcription of the glycogen synthase gene (glgA) in standard strains. In L2(25667R) the gene is not expressed, but transformants of that strain given the cloned chlamydial plasmid increase glgA expression, as does L2(434). The cloned plasmid is retained, replicated, and expressed in transformants over at least 5 passages, and GFP is expressed when transformed into growing L2(25667R). This transformation system will allow study of chlamydial gene function in pathogenesis.
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http://dx.doi.org/10.1016/j.micpath.2013.08.003DOI Listing
December 2013

Dendrimer-enabled DNA delivery and transformation of Chlamydia pneumoniae.

Nanomedicine 2013 Oct 29;9(7):996-1008. Epub 2013 Apr 29.

Department of Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI, USA.

Unlabelled: The chlamydiae are important human pathogens. Lack of a genetic manipulation system has impeded understanding of the molecular bases of virulence for these bacteria. We developed a dendrimer-enabled system for transformation of chlamydiae and used it to characterize the effects of inserting the C. trachomatis plasmid into C. pneumoniae, which lacks any plasmids. The plasmid was cloned into modified yeast vector pEG(KG) and the clone complexed to polyamidoamine dendrimers, producing 50-100 nm spherical particles. HEp-2 cell cultures were infected with C. pneumoniae strain AR-39. Twenty-four hours later, medium was replaced for 3 hours with dendrimer-plasmid complexes, then removed and the medium replaced. Cultures were harvested at various times post-transformation. Real-time PCR and RT-PCR of nucleic acids from transformed cultures demonstrated plasmid replication and gene expression. The cloned plasmid was replicated and expressed in transformants over 5 passages. This system will allow study of chlamydial gene function, allowing development of novel dendrimer-based therapies.

From The Clinical Editor: This team of investigators developed a dendrimer-enabled system for transformation of chlamydiae and successfully utilized it to characterize the effects of inserting the C. trachomatis plasmid into C. pneumonia. This system will allow study of chlamydial gene function, allowing development of novel dendrimer-based therapies.
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http://dx.doi.org/10.1016/j.nano.2013.04.004DOI Listing
October 2013

PAMAM dendrimer-azithromycin conjugate nanodevices for the treatment of Chlamydia trachomatis infections.

Nanomedicine 2011 Dec 19;7(6):935-44. Epub 2011 May 19.

Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, Michigan 48202, USA.

Unlabelled: Chlamydia trachomatis is an important bacterial pathogen known to be etiological in genital infections, as well as several serious disease sequelae, including inflammatory arthritis. Chlamydiae can persist in infection, making treatment with antibiotics such as azithromycin (AZ) a challenge. The authors explore the use of neutral generation-4 polyamidoamine (PAMAM) dendrimers as intracellular drug-delivery vehicles into chlamydial inclusions. Azithromycin was successfully conjugated with the dendrimers, and the conjugate (D-AZ) released ≈ 90% of the drug over 16 hours. The conjugate readily entered both the Chlamydia-infected HEp-2 cells and the chlamydial inclusions. The conjugate was significantly better than free drug in preventing productive infections in the cells when added at the time of infection, and better in reducing the size and number of inclusions when added either 24 hours or 48 hours post infection. These studies show that dendrimers can deliver drugs efficiently to growing intracellular C. trachomatis, even if the organism is in the persistent form.

From The Clinical Editor: In this report, the use of polyamidoamine dendrimers as intracellular drug-delivery vehicles into chlamydial inclusions is investigated. This method results in efficient intracellular delivery of azithromycin to address chlamydia infection.
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http://dx.doi.org/10.1016/j.nano.2011.04.008DOI Listing
December 2011

Targeted delivery of antibiotics to intracellular chlamydial infections using PLGA nanoparticles.

Biomaterials 2011 Sep 8;32(27):6606-13. Epub 2011 Jun 8.

Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA.

Chlamydia trachomatis and Chlamydia pneumoniae are intracellular bacterial pathogens that have been shown to cause, or are strongly associated with, diverse chronic diseases. Persistent infections by both organisms are refractory to antibiotic therapy. The lack of therapeutic efficacy results from the attenuated metabolic rate of persistently infecting chlamydiae in combination with the modest intracellular drug concentrations achievable by normal delivery of antibiotics to the inclusions within which chlamydiae reside in the host cell cytoplasm. In this research, we evaluated whether nanoparticles formulated using the biodegradable poly(d-L-lactide-co-glycolide) (PLGA) polymer can enhance the delivery of antibiotics to the chlamydial inclusion complexes. We initially studied the trafficking of PLGA nanoparticles in Chlamydia-infected cells. We then evaluated nanoparticles for the delivery of antibiotics to the inclusions. Intracellular trafficking studies show that PLGA nanoparticles efficiently concentrate in inclusions in both acutely and persistently infected cells. Further, encapsulation of rifampin and azithromycin antibiotics in PLGA nanoparticles enhanced the effectiveness of the antibiotics in reducing microbial burden. Combination of rifampin and azithromycin was more effective than the individual drugs. Overall, our studies show that PLGA nanoparticles can be effective carriers for targeted delivery of antibiotics to intracellular chlamydial infections.
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http://dx.doi.org/10.1016/j.biomaterials.2011.05.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3133877PMC
September 2011