ABSTRACT
Mitochondrial dysfunction can be associated with a range of clinical manifestations. Here, we report a family with a complex phenotype including combinations of connective tissue, neurological, and metabolic symptoms that were passed on to all surviving children. Analysis of the maternally inherited mtDNA revealed a novel genotype encompassing the haplogroup J - defining mitochondrial DNA (mtDNA) ND5 m.13708G>A (A458T) variant arising on the mtDNA haplogroup H7A background, an extremely rare combination. Analysis of transmitochondrial cybrids with the 13708A-H7 mtDNA revealed a lower mitochondrial respiration, increased reactive oxygen species production (mROS), and dysregulation of connective tissue gene expression. The mitochondrial dysfunction was exacerbated by histamine, explaining why all eight surviving children inherited the dysfunctional histidine decarboxylase allele (W327X) from the father. Thus, certain combinations of common mtDNA variants can cause mitochondrial dysfunction, mitochondrial dysfunction can affect extracellular matrix gene expression, and histamine-activated mROS production can augment the severity of mitochondrial dysfunction. Most important, we have identified a previously unreported genetic cause of mitochondrial disorder arising from the incompatibility of common, nonpathogenic mtDNA variants.
Subject(s)
DNA, Mitochondrial , Histamine , DNA, Mitochondrial/genetics , DNA, Mitochondrial/metabolism , Haplotypes , Histamine/metabolism , Mitochondria/genetics , Mitochondria/metabolism , Connective Tissue/metabolismABSTRACT
OBJECTIVES: Pediatric patients diagnosed with inflammatory bowel disease (IBD) are at risk of suboptimal peak bone mass attainment. This study aimed to understand rates of bone health screening adherence, describe factors associated with dual-energy X-ray absorptiometry (DXA) acquisition, and identify factors associated with abnormal DXA. METHODS: We performed a retrospective cohort study of pediatric IBD patients over a 10-year time frame. We included IBD patients (2-20 years of age) enrolled in ImproveCareNow and excluded patients with primary metabolic bone disease. Time-to-event methods and multivariable logistic regression were employed to identify factors associated with DXA acquisition and abnormal DXA. RESULTS: In 676 patients, 464 (68.63%) pediatric patients with IBD had a risk factor for low bone mineral density (BMD); 137 (29.53%) underwent an initial DXA scan. Quiescent disease was significantly associated with a reduced likelihood of DXA (hazard ratio [HR]: 0.48; 95% confidence interval [CI]: 0.24-0.97), while weight z-score <-2 was significantly associated with DXA performance (HR: 2.07; 95% CI: 1.08-3.98). Abnormal DXA results (BMD z-score ≤-1) occurred in 59 (35.54%) individuals. After adjusting for visit diagnosis, delayed puberty, severe disease course, 6 months or greater of steroid exposure, and history of fracture, BMI z-score <-1 (odds ratio: 5.45; 95% CI: 2.41-12.33) was associated with abnormal DXA. CONCLUSIONS: DXA screening occurred in less than one-third of eligible pediatric IBD patients. Compliance was more common in patients with a weight z-score <-2 and less common in those with quiescent disease. BMI strongly predicted abnormal DXA results when adjusting for risk factors for abnormal BMD.
Subject(s)
Bone Diseases, Metabolic , Inflammatory Bowel Diseases , Humans , Child , Absorptiometry, Photon/adverse effects , Absorptiometry, Photon/methods , Bone Density , Retrospective Studies , Inflammatory Bowel Diseases/complications , Inflammatory Bowel Diseases/diagnostic imaging , Bone Diseases, Metabolic/complications , Bone Diseases, Metabolic/diagnosisABSTRACT
Diabetes is associated with impaired glucose metabolism in the presence of excess insulin. Glucose and fatty acids provide reducing equivalents to mitochondria to generate energy, and studies have reported mitochondrial dysfunction in type II diabetes patients. If mitochondrial dysfunction can cause diabetes, then we hypothesized that increased mitochondrial metabolism should render animals resistant to diabetes. This was confirmed in mice in which the heart-muscle-brain adenine nucleotide translocator isoform 1 (ANT1) was inactivated. ANT1-deficient animals are insulin-hypersensitive, glucose-tolerant, and resistant to high fat diet (HFD)-induced toxicity. In ANT1-deficient skeletal muscle, mitochondrial gene expression is induced in association with the hyperproliferation of mitochondria. The ANT1-deficient muscle mitochondria produce excess reactive oxygen species (ROS) and are partially uncoupled. Hence, the muscle respiration under nonphosphorylating conditions is increased. Muscle transcriptome analysis revealed the induction of mitochondrial biogenesis, down-regulation of diabetes-related genes, and increased expression of the genes encoding the myokines FGF21 and GDF15. However, FGF21 was not elevated in serum, and FGF21 and UCP1 mRNAs were not induced in liver or brown adipose tissue (BAT). Hence, increased oxidation of dietary-reducing equivalents by elevated muscle mitochondrial respiration appears to be the mechanism by which ANT1-deficient mice prevent diabetes, demonstrating that the rate of mitochondrial oxidation of calories is important in the etiology of metabolic disease.
Subject(s)
Adenine Nucleotide Translocator 1/genetics , Diabetes Mellitus, Type 2/genetics , Fibroblast Growth Factors/genetics , Growth Differentiation Factor 15/genetics , Adenine Nucleotide Translocator 1/deficiency , Adipose Tissue, Brown/metabolism , Adipose Tissue, Brown/pathology , Animals , Cell Proliferation/genetics , Diabetes Mellitus, Type 2/metabolism , Diabetes Mellitus, Type 2/pathology , Diet, High-Fat/adverse effects , Energy Metabolism/genetics , Glucose/metabolism , Humans , Insulin Resistance/genetics , Mice , Mitochondria, Muscle/genetics , Mitochondria, Muscle/metabolism , Mitochondria, Muscle/pathology , Muscle, Skeletal/metabolism , Reactive Oxygen Species/metabolism , Transcriptome/genetics , Uncoupling Protein 1/geneticsABSTRACT
To develop an understanding of the magnetism on one-dimensional lattices, one of the great challenges is to identify novel model systems with enough chemical flexibility to design the magnetic interactions in measurable samples. To contribute to this endeavor, we present a number of bichalcogenides with similar trigonal packing of magnetic chains. These chains consist of 3d transition-metal (TM) ions that are 6-fold-coordinated by S or Se. Each TM coordination can be described as a trigonally distorted octahedron that shares faces with two neighboring octahedra. A unique ability with these model systems is that an entity with electric polarity can be introduced between the chains that causes the TM ions in the chains to shift to polar positions, thereby allowing for magnetoelectric coupling. By a comparison of the macroscopic data of polar and nonpolar chains with either S = 1 or S = 3/2, it is obvious that the magnetic properties are affected by the indirect electric polarity from the entity between the chains.
ABSTRACT
When CsCl, BaS, BaO, V, and S are reacted in a solid-state reaction under inert conditions, pure powders and single crystals of senary CsBa6V4S12ClO4 can be obtained. Its unique crystal structure has the symmetry R3Ì H (no. 148) and unit cell parameters a = 9.0575(2) and c = 28.339(1) Å. The crystal structure contains polar units [VS3O]3- and a complex BaS7ClO2 coordination. The compound gets its deep-red color from a low-energy charge transfer, which can be explained by an electron transfer from S2- to V5+. In the near-infrared range, down-converted fluorescence occurs at 1.06 and 0.90 eV, and both emissions appear <450 ps after excitation at about 1.27 eV.
ABSTRACT
Six La ABB'O6 ( A = Ca, Sr; B = Co, Ni; B' = Ru, Os) double perovskites were synthesized, several for the first time, and their crystal structures and magnetic behavior were characterized with neutron powder diffraction and direct-current and alternating-current magnetometry. All six compounds crystallize with P21 /n space group symmetry, resulting from a- a- c+ octahedral tilting and complete rock salt ordering of transition-metal ions. Despite the electronic configurations of the transition-metal ions, either d8-d3 or d7-d3, not one of the six compounds shows ferromagnetism as predicted by the Goodenough-Kanamori rules. LaSrNiOsO6, LaSrNiRuO6, and LaCaNiRuO6 display long-range antiferromagnetic order, while LaCaNiOsO6, LaCaCoOsO6, and LaSrCoOsO6 exhibit spin-glass behavior. These compounds are compared to the previously studied LaCaCoRuO6 and LaSrCoRuO6, both of which order antiferromagnetically. The observed variations in magnetic properties can be attributed largely to the response of competing superexchange pathways due to changes in B-O- B' bond angles, differences in the radial extent of the 4d ( B' = Ru) and 5d ( B' = Os) orbitals, and filling of the t2g orbitals of the 3d ion.
ABSTRACT
Arsenic-72 ((72)As) and (77)As have nuclear properties useful for positron emission tomography (PET) and radiotherapy, respectively. The thiophilic nature of arsenic led to the evaluation of dithioarylarsines for potential use in radiopharmaceuticals. Several dithioarylarsines were synthesized from their arylarsonic acids and dithiols and were fully characterized by NMR, ESI-MS, and X-ray crystallography. This chemistry was translated to the no-carrier-added (nca) (77)As level. Because arsenic was available at the nca nanomolar level only as [(77)As]arsenate, this required addition of an aryl group directly to the As to form the [(77)As]arylarsonic acid. The [(77)As]arsenate was reduced from (77)As (V) to (77)As (III), and a modified Bart reaction was used to incorporate the aryl ring onto the (77)As, which was followed by dithiol addition. Various modifications and optimizations resulted in 95% radiochemical yield of nca [(77)As]p-ethoxyphenyl-1,2-ethanedithiolatoarsine.
Subject(s)
Arsenicals/chemistry , Radiopharmaceuticals/chemistry , Arsenicals/chemical synthesis , Chemistry Techniques, Synthetic , Crystallography, X-Ray , Magnetic Resonance Spectroscopy , Molecular Structure , Radiopharmaceuticals/chemical synthesis , Spectrometry, Mass, Electrospray Ionization , Toluene/analogs & derivatives , Toluene/chemistryABSTRACT
The synthesis, structure, and properties of the ordered double perovskites Sr2FeOsO6, Ca2FeOsO6, and SrCaFeOsO6 are reported. The latter two compounds have monoclinic P21/n symmetry and a(-)a(-)b(+) tilting of the octahedra, while Sr2FeOsO6 is tetragonal with I4/m symmetry and a(0)a(0)c(-) tilting. Magnetic measurements indicate and neutron powder diffraction studies confirm that Ca2FeOsO6 is a ferrimagnet with a Curie temperature of 350 K. The ferrimagnetism is retained if half of the Ca(2+) ions are replaced with larger Sr(2+) ions to form SrCaFeOsO6 (T(C) = 210 K). This substitution reduces the degree of octahedral tilting, but unlike most perovskites, the magnetic ordering temperature decreases as the Fe-O-Os bond angles approach a linear geometry. In contrast, Sr2FeOsO6 orders antiferromagnetically, as previously reported. X-ray absorption spectroscopy confirms the assignment of Fe(III) and Os(V) oxidation states for all three compounds. In these insulating double perovskites, the magnetic ground state is governed by a competition between the four-bond Fe-O-Os-O-Fe antiferromagnetic superexchange coupling of Fe(III) ions and the two-bond Fe-O-Os antiferromagnetic superexchange coupling between neighboring Fe(III) and Os(V) ions. When the Fe-O-Os bonds are linear, as they are in the c direction in Sr2FeOsO6, the four-bond coupling between Fe(III) ions prevails. The competition shifts in favor of antiferromagnetic coupling of Fe(III) and Os(V) as the Fe-O-Os bond angles bend in response to chemical pressure.
ABSTRACT
Adenine nucleotide translocator (ANT) is a mitochondrial protein involved in the exchange of ADP and ATP across the mitochondrial inner membrane. It plays a crucial role in cellular energy metabolism by facilitating the transport of ATP synthesized within the mitochondria to the cytoplasm. The isoform ANT1 predominately expresses in cardiac and skeletal muscles. Mutations or dysregulation in ANT1 have been implicated in various mitochondrial disorders and neuromuscular diseases. We aimed to examine whether ANT1 deletion may affect mitochondrial redox state in our established ANT1-deficient mice. Hearts and quadriceps resected from age-matched wild type (WT) and ANT1-deficient mice were snap-frozen in liquid nitrogen. The Chance redox scanner was utilized to perform 3D optical redox imaging. Each sample underwent scanning across 3-5 sections. Global averaging analysis showed no significant differences in the redox indices (NADH, flavin adenine dinucleotide containing-flavoproteins Fp, and the redox ratio Fp/(NADH+Fp) between WT and ANT1-deficient groups. However, quadriceps had higher Fp than hearts in both groups (p = 0.0004 and 0.01, respectively). Furthermore, the quadriceps were also more oxidized (a higher redox ratio) than hearts in WT group (p = 0.004). NADH levels were similar in all cases. Our data suggest that under non-stressful physical condition, the ANT1-deficient muscle cells were in the same mitochondrial state as WT ones and that the significant difference in the mitochondrial redox state between quadriceps and hearts found in WT might be diminished in ANT1-deficient ones. Redox imaging of muscles under physical stress can be conducted in future.
ABSTRACT
Food insecurity is a rising concern for US households and leads to adverse child health outcomes. Pediatric gastroenterology providers are uniquely equipped to help guide families experiencing this challenge given their specialized training in nutritional support and dietary therapy for disease management. Hence, this study aimed to evaluate food insecurity screening practices from the perspectives of patient caregivers and healthcare providers in a tertiary pediatric gastroenterology practice. A survey was administered to 1279 caregivers and 121 providers. Of the 248 completed caregiver responses, 10%-15% reported being asked about food insecurity. Among the 36 healthcare provider responses, 53% expressed comfort in conducting food insecurity screening but only 14% routinely screened. The most cited barrier to screening was the lack of readily available patient resources. Further research is imperative to address these screening barriers and assess the impact of food insecurity screening and interventions on pediatric gastrointestinal health outcomes.
ABSTRACT
Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic SRSF2P95H/+ mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator PINK1 to remove a poison intron, increasing the stability and abundance of PINK1 mRNA and protein. SRSF2P95H-induced mitochondrial dysfunction increased PINK1 expression through this mechanism, which is essential for survival of SRSF2P95H/+ cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in SRSF2P95H/+ cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through PINK1 splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in SRSF2P95H mutant MDS and AML.
ABSTRACT
Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic SRSF2P95H/+ mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator PINK1 to remove a poison intron, increasing the stability and abundance of PINK1 mRNA and protein. SRSF2P95H-induced mitochondrial dysfunction increased PINK1 expression through this mechanism, which is essential for survival of SRSF2P95H/+ cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in SRSF2P95H/+ cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through PINK1 splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in SRSF2P95H mutant MDS and AML.
Subject(s)
Leukemia, Myeloid, Acute , Mitochondria , Mitophagy , Protein Kinases , Serine-Arginine Splicing Factors , Animals , Humans , Mice , Amino Acid Substitution , Cell Line, Tumor , Hematologic Neoplasms/genetics , Hematologic Neoplasms/pathology , Hematologic Neoplasms/metabolism , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/pathology , Leukemia, Myeloid, Acute/metabolism , Mitochondria/genetics , Mitochondria/metabolism , Mitochondria/pathology , Mitophagy/genetics , Mutation, Missense , Myelodysplastic Syndromes/genetics , Myelodysplastic Syndromes/pathology , Myelodysplastic Syndromes/metabolism , Protein Kinases/genetics , Protein Kinases/metabolism , RNA Splicing , Serine-Arginine Splicing Factors/genetics , Serine-Arginine Splicing Factors/metabolismABSTRACT
The insulating, fully ordered, double perovskite Sr2CoOsO6 undergoes two magnetic phase transitions. The Os(VI) ions order antiferromagnetically with a propagation vector k = (1/2, 1/2, 0) below TN1 = 108 K, while the high-spin Co(II) ions order antiferromagnetically with a propagation vector k = (1/2, 0, 1/2) below TN2 = 70 K. Ordering of the Os(VI) spins is accompanied by a structural distortion from tetragonal I4/m symmetry to monoclinic I2/m symmetry, which reduces the frustration of the face centered cubic lattice of Os(VI) ions. Density functional theory calculations show that the long-range Os-O-Co-O-Os and Co-O-Os-O-Co superexchange interactions are considerably stronger than the shorter Os-O-Co interactions. The poor energetic overlap between the 3d orbitals of Co and the 5d orbitals of Os appears to be responsible for this unusual inversion in the strength of short and long-range superexchange interactions.
ABSTRACT
Like any athlete, female athletes may be tempted to use prohibited substances during competition or training to enhance their performance. Anti-doping tests performed on female athletes in summer Olympic sports from two geographical areas: Australia/ New Zealand, and France were compared. First, the distribution of sample collections across different sports disciplines, as well as the distribution of substances was investigated. Then the distribution of collections and substances detected in the five sports categories (Strength/Speed, Endurance, Mixed, Motor Skills with High Energy Expenditure, and Motor Skills with Low Energy Expenditure) were studied with consideration of therapeutic use exemptions obtained by the athlete. Australia/New Zealand and France were similar in their overall number of anti-doping collections performed. Likewise, both regions had the same sports disciplines (athletics, aquatics, cycling) and sport categories (Mixed and Endurance) as having the highest number of sample collections. The Motor Skills with High Energy Expenditure, and Motor Skills with Low Energy Expenditure categories had the lowest number of sample collections. However, the number of substances detected was significantly different (p < 0.05) with a greater number of substances found in the French data. There were a few substances in common between the two geographical areas, namely prednisone/prednisolone, carboxy-THC, terbutaline, vilanterol and methylphenidate, but most were different. In-competition tests were the category where most of the AAFs were found.
ABSTRACT
OBJECTIVE: Mitochondrial disorders are often characterized by muscle weakness and fatigue. Null mutations in the heart-muscle adenine nucleotide translocator isoform 1 (ANT1) of both humans and mice cause cardiomyopathy and myopathy associated with exercise intolerance and muscle weakness. Here we decipher the molecular underpinnings of ANT1-deficiency-mediated exercise intolerance. METHODS: This was achieved by correlating exercise physiology, mitochondrial function and metabolomics of mice deficient in ANT1 and comparing this to control mice. RESULTS: We demonstrate a peripheral limitation of skeletal muscle mitochondrial respiration and a reduced complex I respiration in ANT1-deficient mice. Upon exercise, this results in a lack of NAD+ leading to a substrate limitation and stalling of the TCA cycle and mitochondrial respiration, further limiting skeletal muscle mitochondrial respiration. Treatment of ANT1-deficient mice with nicotinamide riboside increased NAD+ levels in skeletal muscle and liver, which increased the exercise capacity and the mitochondrial respiration. CONCLUSION: Increasing NAD+ levels with nicotinamide riboside can alleviate the exercise intolerance associated to ANT1-deficiency, indicating the therapeutic potential of NAD+-stimulating compounds in mitochondrial myopathies.
Subject(s)
Adenine Nucleotide Translocator 1 , Mitochondrial Myopathies , NAD , Niacinamide , Physical Conditioning, Animal , Pyridinium Compounds , Adenine Nucleotide Translocator 1/genetics , Animals , Mice , Mitochondrial Myopathies/genetics , Muscle Weakness , Niacinamide/analogs & derivatives , Niacinamide/pharmacology , Protein Isoforms , Pyridinium Compounds/pharmacologyABSTRACT
Inside cells, the immunomodulator methotrexate (MTX) undergoes the addition of glutamates to form methotrexate polyglutamates (MTX-Glu)-promising biomarkers of systemic exposure and treatment response to MTX in rheumatology. MTX-Glu are underexplored in Inflammatory Bowel Disease (IBD), with no data in pediatrics. In this cross-sectional secondary analysis, we assessed the relationships between MTX-Glu and MTX dose and treatment response in pediatric IBD. Twenty-one children with IBD, receiving maintenance therapy with infliximab (IFX) and MTX, had MTX-Glu1-6 concentrations and IFX troughs/antibodies measured and disease activity assessed for comparison in remission vs. active IBD using non-parametric tests, with associations explored using Spearman's correlation (ρ) and regression analyses; SASv9.4 (α = 0.05). Total and long-chain MTX-Glu correlated with MTX dose (ρ = 0.51 and 0.56, respectively; p ≤ 0.02). In children with Crohn's disease (n = 19), short-chain MTX-Glu1-2 were 2.5-fold higher in remission vs. active disease, approaching statistical significance (p = 0.066), with no statistical differences in IFX trough (p = 0.549) between groups. Our study highlights a potential role for long-chain MTX-Glu in the therapeutic drug monitoring of MTX in IBD. It is the first study in pediatric IBD and, although statistical significance was not reached, our findings also suggest that higher short-chain MTX-Glu levels may be associated with IBD treatment response to MTX in children.
ABSTRACT
This investigation describes the formulation and characterization of rheologically structured vehicles (RSVs) designed for improved drug delivery to the vagina. Interactive, multicomponent, polymeric platforms were manufactured containing hydroxyethylcellulose (HEC, 5% w/w) polyvinylpyrrolidone (PVP, 4% w/w), Pluronic (PL, 0 or 10% w/w), and either polycarbophil (PC, 3% w/w) or poly(methylvinylether-co-maleic anhydride) (Gantrez S97, 3% w/w) as a mucoadhesive agent. The rheological (torsional and dynamic), mechanical (compressional), and mucoadhesive properties were characterized and shown to be dependent upon the mucoadhesive agent used and the inclusion/exclusion of PL. The dynamic rheological properties of the gel platforms were also assessed following dilution with simulated vaginal fluid (to mimic in vivo dilution). RSVs containing PC were more rheologically structured than comparator formulations containing GAN. This trend was also reflected in formulation hardness, compressibility, consistency, and syringeability. Moreover, formulations containing PL (10% w/w) were more rheologically structured than formulations devoid of PL. Dilution with simulated vaginal fluids significantly decreased rheological structure, although RSVs still retained a highly elastic structure (G' > G'' and tan delta < 1). Furthermore, RSVs exhibited sustained drug release properties that were shown to be dependent upon their rheological structure. It is considered that these semisolid drug delivery systems may be useful as site-retentive platforms for the sustained delivery of therapeutic agents to the vagina.
Subject(s)
Drug Delivery Systems/methods , Gels/chemistry , Adhesiveness , Administration, Intravaginal , Delayed-Action Preparations , Mechanical Phenomena , RheologyABSTRACT
Nuclear-encoded mutations causing metabolic and degenerative diseases have highly variable expressivity. Patients sharing the homozygous mutation (c.523delC) in the adenine nucleotide translocator 1 gene (SLC25A4, ANT1) develop cardiomyopathy that varies from slowly progressive to fulminant. This variability correlates with the mitochondrial DNA (mtDNA) lineage. To confirm that mtDNA variants can modulate the expressivity of nuclear DNA (nDNA)-encoded diseases, we combined in mice the nDNA Slc25a4-/- null mutation with a homoplasmic mtDNA ND6P25L or COIV421A variant. The ND6P25L variant significantly increased the severity of cardiomyopathy while the COIV421A variant was phenotypically neutral. The adverse Slc25a4-/- and ND6P25L combination was associated with impaired mitochondrial complex I activity, increased oxidative damage, decreased l-Opa1, altered mitochondrial morphology, sensitization of the mitochondrial permeability transition pore, augmented somatic mtDNA mutation levels, and shortened lifespan. The strikingly different phenotypic effects of these mild mtDNA variants demonstrate that mtDNA can be an important modulator of autosomal disease.
Subject(s)
Cardiomyopathies/genetics , DNA, Mitochondrial/genetics , Electron Transport Complex I/genetics , Mitochondria/genetics , Animals , Disease Models, Animal , Mice , Mice, Inbred C57BL , MutationABSTRACT
TMC 120 (Dapivirine) is a potent non-nucleoside reverse transcriptase inhibitor that is presently being developed as a vaginal HIV microbicide. To date, most vaginal microbicides under clinical investigation have been formulated as single-dose semi-solid gels, designed for application to the vagina before each act of intercourse. However, a clear rationale exists for providing long-term, controlled release of vaginal microbicides in order to afford continuous protection against heterosexually transmitted HIV infection and to improve user compliance. In this study we report on the incorporation of various pharmaceutical excipients into TMC 120 silicone, reservoir-type intravaginal rings (IVRs) in order to modify the controlled release characteristics of the microbicide. The results demonstrate that TMC 120 is released in zero-order fashion from the rings over a 28-day period and that release parameters could be modified by the inclusion of release-modifying excipients in the IVR. The hydrophobic liquid excipient isopropyl myristate had little effect on steady-state daily release rates, but did increase the magnitude and duration of burst release in proportion to excipient loading in the IVR. By comparison, the hydrophobic liquid poly(dimethylsiloxane) had little effect on TMC 120 release parameters. A hydrophilic excipient, lactose, had the surprising effect of decreasing TMC 120 burst release while increasing the apparent steady-state daily release in a concentration-dependent manner. Based on previous cell culture data and vaginal physiology, TMC120 is released from the various ring formulations in amounts potentially capable of maintaining a protective vaginal concentration. It is further predicted that the observed release rates may be maintained for at least a period of 1 year from a single ring device. TMC 120 release profiles and the mechanical properties of rings could be modified by the physicochemical nature of hydrophobic and hydrophilic excipients incorporated into the IVRs.