Browsing by Author "Khan, Aneal"
Now showing 1 - 12 of 12
Results Per Page
Sort Options
Item Open Access Advancing the Art of Mitochondrial Diagnostics and Therapeutics(2017) Newell, Christopher; Khan, Aneal; Shearer, Jane; Rho, Jong; Childs, Sarah; Shutt, Timothy; Haqq, AndreaObjective: Mitochondrial diseases are panethnic genetic disorders, affecting 1:5000 individuals. Currently with no cure, challenges exist in patient diagnosis, measurement of mitochondrial function, and effective therapies. The primary emphasis of this dissertation was to explore diagnostic and therapeutic targets for mitochondrial disease. Investigated therapies included; mesenchymal stem cell (MSC) therapy, dietary interventions, and side alternating vibration training (SAVT). Novel diagnostic approaches employed were; the hybrid blue-clear native polyacrylamide gel electrophoresis (BCN-PAGE), and circulating cell-free mitochondrial DNA (cf-mtDNA) techniques. Methods: C57BL/6 mice were intravenously treated with MSCs following the induction of metabolic inflammation through prolonged high-fat (HF) feeding. A separate cohort of BTBR, autism-phenotype, mice were treated with a ketogenic diet (KD) to examine the impact on mitochondrial dynamics in a disease commonly experiencing mitochondrial dysfunction. These projects involved a combination of mitochondrial bioenergetics (high resolution respirometry), gut microbiome (fecal and cecal), gene expression (qRT-PCR, gene microarray), and mitochondrial morphology (confocal microscopy) experimentation to evaluate the mitochondrial-specific response to each therapy. Thirdly, clinical assessment of SAVT as a therapeutic in mitochondrial disease patients was performed using a 12-week cross-over study design using peak jumping power (PJP) as a primary functional measurement of mitochondrial function. Diagnostically, mitochondria were isolated from control and mitochondrial disease patient skin fibroblasts to compare our BCN-PAGE technique to existing diagnoses. Secondly, blood was drawn from both control and mitochondrial disease patients for clinical comparisons of mtDNA hapolotyping using our cf-mtDNA technique. Results: Therapeutic studies indicate that MSCs improve metabolic capacity, induce widespread gene shifting, and promote healthy mitochondrial morphology in a model of metabolic inflammation. Moreover, KD administration exerts tissue-specific effects including increased mitochondrial turnover in liver, while the brain remained tightly regulated. Clinically, SAVT was well tolerated in mitochondrial disease patients, with improvements in PJP being measured following therapy. Diagnostically, both BCN-PAGE and cf-mtDNA techniques were successfully able to corroborate clinical diagnostic findings. Conclusions: Experiments completed in this dissertation provide insight into various therapeutic opportunities for both mitochondrial disease and diseases involving mitochondrial dysfunction. Furthermore, our less-invasive diagnostic techniques may be useful to monitor the response to future therapies for mitochondrial disease.Item Open Access Anterior Hypopituitarism and Treatment Response in Hunter Syndrome: A Comparison of Two Patients(2016-11-28) Nour, Munier A.; Luca, Paola; Stephure, David; Wei, Xing-Chang; Khan, AnealHypopituitarism is a clinically important diagnosis and has not previously been reported in Hunter syndrome. We contrast two cases with anatomic pituitary anomalies: one with anterior panhypopituitarism and the other with intact pituitary function. Patient 1, a 10-year-old boy with Hunter syndrome, was evaluated for poor growth and an ectopic posterior pituitary gland. Endocrine testing revealed growth hormone (GH) deficiency, secondary adrenal insufficiency, and tertiary hypothyroidism. An improvement in growth velocity with hormone replacement (GH, thyroxine, and corticosteroid) was seen; however, final adult height remained compromised. Patient 2, a 13-year-old male with Hunter syndrome, was evaluated for growth failure. He had a large empty sella turcica with posteriorly displaced pituitary. Functional endocrine testing was normal and a trial of GH-treatment yielded no significant effect. Panhypopituitarism associated with pituitary anomalies has not been previously reported in Hunter syndrome and was an incidental finding of significant clinical importance. In the setting of documented anterior hypopituitarism, while hormone replacement improved growth velocity, final height remained impaired. In patient 2 with equivocal GH-testing results, treatment had no effect on linear growth. These cases highlight the importance of careful clinical assessment in Hunter syndrome and that judicious hormone replacement may be indicated in individual cases.Item Open Access Development and Optimization of a Cellular Model for the Dilated Cardiomyopathy with Ataxia Syndrome(2019-01-22) Machiraju, Pranav; Greenway, Steven C.; Khan, Aneal; Shutt, Timothy E.The dilated cardiomyopathy with ataxia syndrome (DCMA) is an autosomal recessive disorder caused by mutations in the poorly-characterized but essential gene DNAJC19. Tissue studies have shown that the loss of functional DNAJC19 protein has major consequences for mitochondrial structure and function, but the mechanism of disease remains unknown. Given that affected individuals frequently die in early childhood due to intractable heart failure, the development of therapeutics is imperative. Cellular modelling in vitro represents an important first step in characterizing the disease phenotype and testing the effect of potential drug therapies. This thesis aimed to characterize mitochondrial structural abnormalities in DCMA using patient dermal fibroblasts and cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs). We hypothesized that patient cells would identify abnormalities in mitochondrial structure and function and that treatment with the mitochondrially-targeted peptide SS-31 would be effective in correcting these deficiencies. We report increased mitochondrial fragmentation and increased production of reactive oxygen species (ROS) in fibroblasts, both of which improved following treatment with SS-31. A similar phenotype was found in iPSC-CMs. Additional work to improve our iPSC-CM model used the pan-retinoic acid receptor inverse agonist BMS493 to direct the specification and maturation of iPSCs into ventricular cardiomyocytes. Cells treated with BMS493 demonstrated a slower beating rate and increased contractility compared to untreated cells. This thesis provides a previously-lacking characterization of DCMA mitochondria in fibroblasts and iPSC-CMs, identifies SS-31 as a potentially effective therapeutic for DCMA and developed and improved a patient-, tissue-, and disease-specific in vitro model for DCMA using iPSC-CMs that will be useful for further characterization and modelling of DCMA and other cardiomyopathies.Item Open Access MITOCHONDRIAL SKELETAL DISORDERS PROVIDE INSIGHT INTO THE EFFECT OF MITOCHONDRIAL PROTEOSTATIC STRESS ON STEROIDOGENESIS(2023-09-22) Zhao, Tian Rui; Shutt, Timothy; Khan, Aneal; Innes, Micheil; Yang, Guang; Bech-Hansen, TorbenMitochondria are best known for their role in energy production, and impairments in this essential function are generally thought to cause mitochondrial disease, which typically affects organs and tissues with high energy demand. However, increasing evidence shows that impairments to other critical mitochondrial functions such as lipid metabolism, and steroidogenesis can also contribute to mitochondrial diseases. In this thesis, we identified a group of mitochondrial diseases where mitochondrial protein homeostasis is disrupted, which we termed mitochondrial skeletal disorders, as the patients exhibited phenotypes such as skeletal dysplasia, short stature, and cataracts. In addition, further investigation identified a potential mechanism by which altered mitochondrial protein homeostasis and increased steroidogenesis may contribute to these patient phenotypes. First, we identified novel pathogenic variants in phosphatidylserine decarboxylase (PISD) gene from patients with short stature, neurodevelopmental issues, and cataracts. We demonstrated that the variants impair function and stability of PISD and are likely causative of their disease. We also identified evidence for impaired activity of inner mitochondrial membrane (IMM) proteases, suggesting dysfunctions in mitochondrial protein homeostasis. To further investigate the mechanism by which impaired mitochondrial proteostasis may lead to these phenotypes, we tested the hypothesis that impaired mitochondrial proteostasis can lead to overproduction of the stress hormone cortisol, as this could potentially explain the patients’ phenotypes described above. Using both pharmacological and genetic stresses to impair mitochondrial proteostasis, we showed impaired mitochondrial protein import activates STARD1, a mitochondrial protein crucial in steroidogenesis. We then showed that increased cortisol production is STARD1 dependent and follows a biphasic response to mitochondrial stress. Overall, these findings expand our current understanding of mitochondrial disease and link mitochondrial quality control and steroidogenesis as potential disease mechanisms.Item Open Access Primary Hyperparathyroidism: An Overview(2011-06-02) MacKenzie-Feder, Jessica; Sirrs, Sandra; Anderson, Donald; Sharif, Jibran; Khan, AnealPrimary hyperparathyroidism is a common condition that affects 0.3% of the general population. Primary and tertiary care specialists can encounter patients with primary hyperparathyroidism, and prompt recognition and treatment can greatly reduce morbidity and mortality from this disease. In this paper we will review the basic physiology of calcium homeostasis and then consider genetic associations as well as common etiologies and presentations of primary hyperparathyroidism. We will consider emerging trends in detection and measurement of parathyroid hormone as well as available imaging modalities for the parathyroid glands. Surgical indications and approach will be reviewed as well as medical management of primary hyperparathyroidism with bisphosphonates and calcimimetics.Item Open Access Primary Hyperparathyroidism: An Overview(Hindawi Publishing Corporation, 2011-04-09) MacKenzie-Feder, Jessica; Sirrs, Sandra; Anderson, Donald; Sharif, Jibran; Khan, AnealItem Open Access Side alternating vibration training in patients with mitochondrial disease: a pilot study(2017-08-08) Newell, Christopher; Ramage, Barbara; Robu, Ion; Shearer, Jane; Khan, AnealAbstract Background Side alternating vibration training (SAVT) is a mechanical oscillation using a vibrating platform that simulates exercise. We hypothesized that patients with mitochondrial myopathies, who experience muscle weakness, may see an improvement in muscle power with SAVT. Methods Patients with mitochondrial disease started either a treatment (SAVT) or control phase (standing without vibration) for 12 weeks, then 12 weeks of washout, and then a 12-week cross-over. The main outcome measure was peak jump power (PJP). We compared this to a natural history cohort from clinic. Results Seven out of 13 patients completed at least 80% of their SAVT sessions and were analyzed. The ΔPJP after the control phase was −2.7 ± 1.7 W/kg (mean ± SEM), SAVT was +2.8 ± 0.6 W/kg (p < 0.05) and from the natural history cohort was −2.4 ± 0.8 W/kg/year. Conclusions SAVT is well tolerated and may improve muscle power in mitochondrial disease patients.Item Open Access Side-Alternating Vibration Training Improves Muscle Performance in a Patient with Late-Onset Pompe Disease(2009-05-25) Khan, Aneal; Ramage, Barbara; Robu, Ion; Benard, LauraSide-alternating vibration training (SAVT) was used for 15 weeks in a patient with Late-onset Pompe disease who had never used enzyme replacement or chaperone therapy. Prior to the use of SAVT, the patient had experienced declining muscle performance and her 6-minute walk distance decreased from 210 to 155 metres in 6 months. After SAVT, her 6-minute walk distance increased 70% from 166 to 282 metres, muscle jumping power increased by 64% from 83 to 166 watts, isometric knee extensor strength increased 17% from 38 to 44 Nm, and she achieved a more normal pattern of ankle, knee, andjoint kinematics and kinetics. Her functional ability measured through the Rotterdam 9-item score was unchanged at 19/36. There were no elevations in serum creatine kinase or lactate. This is the first report, to our knowledge, of a performance improvement in a patient with Pompe disease using SAVT.Item Open Access Side-Alternating Vibration Training ImprovesMuscle Performance in a Patient with Late-Onset Pompe Disease(Hindawi Publishing Corporation, 2009) Khan, Aneal; Ramage, Barbara; Robu, Ion; Benard, LauraItem Embargo Spectrum of Microarchitectural Bone Disease in Inborn Errors of Metabolism(2020-08-27) Sidhu, Karamjot Kaur; Boyd, Steven Kyle; Khan, Aneal; Kline, Gregory Alan; Manske, Sarah Lynn; Aspinall, Alexander I.Inborn errors of metabolism (IBEMs) are a heterogeneous group of inherited disorders caused by a defect in the synthesis, metabolism, transport, and/or storage of metabolites. Diagnosed patients can often present with compromised bone health and an increased risk for fragility fractures. The current standard for measuring bone health in the general population is bone density assessed by dual-energy X-ray absorptiometry (DXA). However, its utilization in understanding bone status in IBEMs is limited. The primary limiting factor is DXA’s inability to assess cortical and trabecular bone independently, which is important in understanding bone loss that is a result of complex disease processes. In this thesis, macro- and microarchitectural properties of bone were monitored in a wide range of IBEM disorders using new three-dimensional technology, high-resolution peripheral quantitative computed tomography (HR- pQCT). Moreover, bone strength was estimated by employing finite element techniques on HR- pQCT image data. A further examination of these measurements in relationship to genetic mutations, clinical history, and treatment status was investigated in Gaucher disease and hypophosphatasia as a case report and cohort study, respectively. In IBEM patients, both bone density and microarchitecture were impaired when compared to a reference database. The degree of impairment varied between IBEM subtypes, and was significantly greater in IBEMs associated with decreased bone mass mineralization, including hypophosphatasia. Cortical bone density and microarchitecture were also significantly lower in IBEM patients with previous fractures when compared to IBEM patients with no fracture history. Estimated bone strength was also significantly lower in certain IBEM disorders when compared to a reference database, including IBEM disorders of metabolism requiring diet restrictions and disorder of the nervous or muscular system resulting in impaired mobility. Investigations in Gaucher disease and hypophosphatasia suggested disease-targeting therapy may aid in preventing or delaying accelerated bone mass loss that is thought to occur from the IBEM diagnosis. In conclusion, bone density and microarchitecture are largely affected in IBEMs. Future work in understanding how therapeutic interventions, such as bone-altering therapies, impact bone density and microarchitecture in IBEMs may be highly valuable.Item Open Access Spectrum of microarchitectural bone disease in inborn errors of metabolism: a cross-sectional, observational study(2020-09-16) Sidhu, Karamjot; Ali, Bilal; Burt, Lauren A; Boyd, Steven K; Khan, AnealAbstract Background Patients diagnosed with inborn errors of metabolism (IBEM) often present with compromised bone health leading to low bone density, bone pain, fractures, and short stature. Dual-energy X-ray absorptiometry (DXA) is the current gold standard for clinical assessment of bone in the general population and has been adopted for monitoring bone density in IBEM patients. However, IBEM patients are at greater risk for scoliosis, short stature and often have orthopedic hardware at standard DXA scan sites, limiting its use in these patients. Furthermore, DXA is limited to measuring areal bone mineral density (BMD), and does not provide information on microarchitecture. Methods In this study, microarchitecture was investigated in IBEM patients (n = 101) using a new three-dimensional imaging technology high-resolution peripheral quantitative computed tomography (HR-pQCT) which scans at the distal radius and distal tibia. Volumetric BMD and bone microarchitecture were computed and compared amongst the different IBEMs. For IBEM patients over 16 years-old (n = 67), HR-pQCT reference data was available and Z-scores were calculated. Results Cortical bone density was significantly lower in IBEMs associated with decreased bone mass when compared to lysosomal storage disorders (LSD) with no primary skeletal pathology at both the radius and tibia. Cortical thickness was also significantly lower in these disorders when compared to LSD with no primary skeletal pathology at the radius. Cortical porosity was significantly greater in hypophosphatasia when compared to all other IBEM subtypes. Conclusion We demonstrated compromised bone microarchitecture in IBEMs where there is primary involvement of the skeleton, as well as IBEMs where skeletal complications are a secondary outcome. In conclusion, our findings suggest HR-pQCT may serve as a valuable tool to monitor skeletal disease in the IBEM population, and provides insight to the greatly varying bone phenotype for this cohort that can be used for clinical monitoring and the assessment of response to therapeutic interventions.Item Open Access The International Collaborative Gaucher Group GRAF (Gaucher Risk Assessment for Fracture) score: a composite risk score for assessing adult fracture risk in imiglucerase-treated Gaucher disease type 1 patients(2021-02-18) Deegan, Patrick; Khan, Aneal; Camelo, José S; Batista, Julie L; Weinreb, NealAbstract Background Fractures in Gaucher disease type 1 (GD1) patients cause significant morbidity. Fracture risk may be decreased by enzyme replacement therapy (ERT) but not eliminated. When considering initiation of treatment, it is useful to know to what extent fixed patient-specific factors determine risk for future fractures beyond standard risk factors that change with time and treatment, such as decreased bone mineral density. We developed a tool called the GRAF score (Gaucher Risk Assessment for Fracture) that applies 5 widely available characteristics (sex, age at treatment initiation [ATI], time interval between diagnosis and treatment initiation, splenectomy status, history of pre-treatment bone crisis) and provides a practical method to assess future fracture risk when imiglucerase ERT is initiated. Methods Inclusion criteria: GD1 patients in the International Collaborative Gaucher Group Gaucher Registry as of September 2019 initially treated with alglucerase/imiglucerase; known splenectomy status; at least one skeletal assessment on treatment (3216 of 6422 patients). Data were analyzed by ATI group (< 18, ≥ 18 to < 50, or ≥ 50 years of age) using Cox proportional hazards regression with all 5 risk factors included in the multivariable model. A composite risk score was calculated by summing the contribution of each parameter weighted by the strength of its association (regression coefficient) with fracture risk. Results Patients were followed from the date of treatment initiation (or age 18 years for patients if treatment started earlier) to the date of first adult fracture (n = 288 first fracture endpoints), death, or end of follow-up. The GRAF score for each ATI group was associated with a 2.7-fold increased risk of adult fracture for each one-point increase (p < 0.02 for < 18 ATI, p < 0.0001 for ≥ 18 to < 50 ATI and ≥ 50 ATI). Conclusions The GRAF score is a tool to be used with bone density and other modifiable, non-GD-specific risk factors (e.g. smoking, alcohol intake, frailty) to inform physicians and previously untreated GD1 patients about risk for a future fracture after starting imiglucerase regardless of whether there is an eventual switch to an alternative ERT or to substrate reduction therapy. GRAF can also help predict the extent that fracture risk increases if initiation of treatment is further delayed.