Latanoprost and Dorzolamide for the Treatment of Pediatric Glaucoma: The Glaucoma Italian Pediatric Study (Gipsy), Design and Baseline Characteristics

Introduction

To investigate the efficacy of a treatment strategy with latanoprost and dorzolamide in primary pediatric glaucoma patients partially responsive to surgery.

Methods

Single arm, prospective, interventional multicenter study. Primary pediatric glaucoma patients younger than 13 years after a single surgical procedure with IOP between 22 and 26 mmHg were considered eligible. At baseline, patients were allocated to latanoprost monotherapy once daily. Depending on intraocular pressure (IOP) reduction at first visit, the patients were allocated to one of three groups: continuation of latanoprost monotherapy, addition of dorzolamide twice daily, or switch to dorzolamide three times daily. The same approach for allocation in medication groups was used in all subsequent visits. Patients in the dorzolamide monotherapy group with IOP reduction <20% from baseline were considered non-responders and withdrawn. Study treatment and patient follow-up will continue for 3 years or until treatment failure. The primary endpoint is the percentage of responders. Secondary endpoints are time to treatment failure and frequency of adverse events.

Results

A total of 37 patients (69 eyes) were enrolled. The mean age was 4.0 ± 3.8 years, the female/male ratio was 1/1.7, and the majority of patients were Caucasian. Eighty percent of patients had bilateral glaucoma. Goniotomy was the most frequently performed surgery (38.6%), followed by trabeculotomy (22.8%), trabeculectomy (21.1%), and trabeculectomy plus trabeculotomy (17.5%). The baseline IOP was 23.6 ± 1.5 mmHg.

Conclusion

The study population is representative of patients frequently encountered after the first surgery for primary pediatric glaucoma. The study will produce evidence on the medium-term efficacy of a defined pharmacological approach.

Vitamin D3 inhibits TNFα-induced latent HIV reactivation in J-LAT cells

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is known to suppress NF-kB activity by interfering with its pathways. The aim of this study was to investigate the ability of 1,25(OH)2D3 in reducing the reactivation of the HIV virus J-LAT cells, an established model of latently infected cells, which were treated with TNFalpha (100 ng/ml) for 2 h with or without 24 h 1,25(OH)2D3 (100 nM) pretreatment. Reactivation of HIV RNA in J-LAT was evaluated in terms of green fluorescent protein (GFP) expression. The same experimental setting was repeated on T cells from HIV-infected patients. Treatment with TNFalpha was associated with a 16 % increase in GFP+ cells and a five-fold increase in unspliced HIV RNA expression (p < 0.04). Pretreatment of J-LAT cells with 1,25(OH)2D3 for 24 h followed by TNFalpha (100 ng/ml) for 2 h reduced the percentage of GFP+ cells by 8 %; moreover, a 2.4-fold decrease in unspliced HIV RNA expression was observed (p < 0.002). In T cells from patients, treatment with TNFalpha significantly increased unspliced HIV RNA expression (sixfold increase, p < 0.02), whereas prestimulation with 1,25(OH)2D3 reduced its expression (2.5-fold decrease, p < 0.02) compared to controls.1,25(OH)2D3 is able to reduce the ability of TNFalpha to upregulate the transcription of HIV RNA from latently infected cells. These data provide further understanding of the pathogenic mechanisms regulating viral reactivation from latent reservoirs, along with new insight in viral internalization.

Induction of OAS gene family in HIV monocyte infected patients with high and low viral load

BACKGROUND

The innate immunity plays a predominant role in the early control of HIV infection, before the induction of adaptive immune responses. The cytokine secretion operated by the CD4(+) T helper cells is able to induce a response in the innate immunity cells and significantly affect HIV-1 persistence and replication. One of the pathways activated by monocytes to restrain viral infection is the 2' -5' -oligoadenylate synthetase (OAS)/RNase L pathway. OAS is activated by dsRNA and IFNs to produce 2' -5' oligoadenylates, which are activators of RNase L. This enzyme degrades viral and cellular RNAs, thus restricting viral infection.

MATERIALS AND METHODS

We analyzed a microarray dataset obtained from the NCBI Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) databank (accession number GSE18464) in order to verify the modulation of the OAS gene family in CD14 (+) monocytes isolated from 55 subjects, 22 with HIV-1 HVL (high viral load), and 22 with HIV-1 LVL (low viral load), as well as in 11 HIV-1 seronegative controls. We have validated the data on the expression levels of the OAS genes by performing real-time PCR on monocyte from a cohort of HIV infected patients (n = 20), with clinical characteristics similar to those of the patients recruited in the study present in the microarray.

RESULTS

Microarray analysis showed that OAS gene family are significantly upregulated in monocyte of HIV-1 patients with HVL, as compared to LVL patients and to healthy donors. Furthermore, we showed a significant correlation between the OAS gene family and the log2 viral load and CD4 count. These results were confirmed by the in vitro validation.

CONCLUSIONS

Data from this study suggest an involvement for the OAS gene family in the control of HIV-1 infection.

Distribution of Salmonella Serovars and Antimicrobial Susceptibility from Poultry and Swine Farms in Central Vietnam

This study was conducted to estimate the prevalence of Salmonella spp. and their antimicrobial susceptibilities on poultry and swine farms, sampled in 2 regions in Central Vietnam. A total of 67 poultry farms and 46 swine farms were sampled in a period of 5 months (from September 2012 to January 2013). Salmonella spp. was prevalent in 46.3% and 71.7% of poultry and swine farms, respectively. Altogether, 99 non-typhoidal Salmonella were isolated and the most common serovars were Salmonella Weltevreden (19%), followed by Salmonella Typhimurium (12%) and Salmonella 4,[5],12:i:- (11%). Overall, 71 of 99 (72%) Salmonella isolates were resistant to at least one of the 14 antimicrobial agents tested. Both in poultry and swine farms, high levels of resistance were observed for ampicillin, chloramphenicol, ciprofloxacin, sulphamethoxazole and tetracycline. The presence of Salmonella isolates from poultry and swine farms which were resistant to different classes of antimicrobials suggests that alternative control measures to antimicrobials should be implemented. Moreover, an effective policy should be promoted to encourage a prudent use of these agents in animal farming in Vietnam.

Comparative facile methods for preparing graphene oxide-hydroxyapatite for bone tissue engineering

Motivated by the success of using graphene oxide (GO) as a nanofiller of composites, there is a drive to search for this new kind of carbon material as a bioactive component in ceramic materials. In the present study, biomineralized GO was prepared by two different approaches, represented by in situ sol-gel synthesis and biomimetic treatment. It was found that in the biocomposites obtained by the sol-gel approach, the spindle-like hydroxyapatite nanoparticles, with a diameter of ca. 5 ± 0.37 nm and a length of ca. 70 ± 2.5 nm, were presented randomly and strongly on the surface. The oxygen-containing functional groups, such as hydroxyl and carbonyl, present on the basal plane and edges of the GO sheets, play an important role in anchoring calcium ions, as demonstrated by FT-IR and TEM investigations. A different result was obtained for biocomposites after biomimetic treatment: an amorphous calcium phosphate on GO sheet was observed after 5 days of treatment. These different approaches resulted in a diverse effect on the proliferation and differentiation of osteogenic mesenchymal stem cells. In fact, in biocomposites prepared by the sol-gel approach the expression of an early marker of osteogenic differentiation, ALP, increases with the amount of GO in the first days of cell culture. Meanwhile, biomimetic materials sustain cell viability and proliferation, even if the expression of alkaline phosphatase activity in a basal medium is delayed. These findings may provide new prospects for utilizing GO-based hydroxyapatite biocomposites in bone repair, bone augmentation and coating of biomedical implants and broaden the application of GO sheets in biological areas. Copyright © 2016 John Wiley & Sons, Ltd.

Geo-Epidemiology of Age-Related Macular Degeneration: New Clues Into the Pathogenesis

PURPOSE

To evaluate the demographic, geographic, and race-related variables that account for geographic variability in prevalence rates of age-related macular degeneration (AMD).

DESIGN

Systematic review, meta-regression, and decision-tree analysis.

METHODS

A systematic literature review of PubMed, Medline, Web of Science, and Embase databases identified population-based studies on the prevalence of AMD published before May 2014. Only population-based studies that took place in a spatially explicit geographic area that could be geolocalized, and used retinal photographs and standardized grading classifications, were included. Latitude and longitude data (geolocalization) and the mean annual insolation for the area where survey took place were obtained. Age-standardized prevalence rates across studies were estimated using the direct standardization method. Correlations between the prevalence of AMD and longitude and latitude were obtained by regression analysis. A hierarchical Bayesian meta-regression approach was used to assess the association between the prevalence of AMD and other relevant factors. We further investigated the interplay between location and these factors on the prevalence of AMD using regression based on conditional-inference decision trees.

RESULTS

We observed significant inverse correlations between latitude or longitude, and crude or age-standardized prevalence rates, of early and late AMD (P < .001). Metaregression analysis showed that insolation, latitude, longitude, age, and race have a significant effect on the prevalence rates of early and late AMD (P < .001). Decision-tree analysis identified that the most important predictive variable was race for early AMD (P = .002) and insolation for late AMD (P = .001).

CONCLUSIONS

Geographic position and insolation are key factors in the prevalence of AMD.

Delayed Suprachoroidal Hemorrhage After Pars Plana Vitrectomy: Five-Year Results of a Retrospective Multicenter Cohort Study

PURPOSE

To determine the incidence, risk factors, and outcomes of delayed suprachoroidal hemorrhage after vitrectomy.

DESIGN

Retrospective multicenter cohort study.

METHODS

All consecutive patients who underwent primary vitrectomy, from January 2009 to December 2014, at 4 tertiary vitreoretinal centers in Italy were enrolled. Patient demographics and systemic, ophthalmic, operative, and postoperative data from all centers were extracted from the electronic record system using standardized data collection forms. All eyes that developed delayed suprachoroidal hemorrhage within 48 hours of the end of the vitrectomy were identified as the delayed suprachoroidal hemorrhage group; all other eyes that underwent vitrectomy in the same period, without delayed suprachoroidal hemorrhage, were considered the control group.

RESULTS

From a total of 4852 vitrectomy procedures, 39 cases of delayed suprachoroidal hemorrhage (0.8%) were identified. Multivariable logistic regression showed that significant risk factors for developing delayed suprachoroidal hemorrhage included advancing age (odds ratio [OR], 2.22; P < .001), longer axial length (OR, 2.57; P < .001), presence of rhegmatogenous retinal detachment (OR, 3.27; P = .005), extensive intraoperative photocoagulation (OR, 4.94; P < .001), and emesis postoperatively (OR, 24.39; P < .001). Decision-tree analysis showed that the stronger predictors of delayed suprachoroidal hemorrhage were emesis postoperatively (P < .001) and extensive intraoperative photocoagulation (P < .001). After a mean follow-up of 27 ± 8 months, the best-corrected visual acuity decreased from 1.3 preoperatively to 1.6 logarithm of minimal angle of resolution at last follow-up (P < .001).

CONCLUSIONS

Delayed suprachoroidal hemorrhage occurs in 0.8% of vitrectomized eyes. The main risk factors are postoperative emesis and intraoperative extensive photocoagulation.

NPY-Y1 coexpressed with NPY-Y5 receptors modulate anxiety but not mild social stress response in mice

The Y1 and Y5 receptors for neuropeptide Y have overlapping functions in regulating anxiety. We previously demonstrated that conditional removal of the Y1 receptor in the Y5 receptor expressing neurons in juvenile Npy1r(Y5R-/-) mice leads to higher anxiety but no changes in hypothalamus-pituitary-adrenocortical axis activity, under basal conditions or after acute restraint stress. In the present study, we used the same conditional system to analyze the specific contribution of limbic neurons coexpressing Y1 and Y5 receptors on the emotional and neuroendocrine responses to social chronic stress, using different housing conditions (isolation vs. group-housing) as a model. We demonstrated that control Npy1r(2lox) male mice housed in groups show increased anxiety and hypothalamus-pituitary-adrenocortical axis activity compared with Npy1r(2lox) mice isolated for six weeks immediately after weaning. Conversely, Npy1r(Y5R-/-) conditional mutants display an anxious-like behavior but no changes in hypothalamus-pituitary-adrenocortical axis activity as compared with their control littermates, independently of housing conditions. These results suggest that group housing constitutes a mild social stress for our B6129S mouse strain and they confirm that the conditional inactivation of Y1 receptors specifically in Y5 receptor containing neurons increases stress-related anxiety without affecting endocrine stress responses.

Long-term therapy with temozolomide is a feasible option for newly diagnosed glioblastoma: a single-institution experience with as many as 101 temozolomide cycles

OBJECT

The objective of this study was to report the authors' experience with the long-term administration of temozolomide (TMZ; > 6 cycles, up to 101) in patients with newly diagnosed glioblastoma and to analyze its feasibility and safety as well as its impact on survival. The authors also compared data obtained from the group of patients undergoing long-term TMZ treatment with data from patients treated with a standard TMZ protocol.

METHODS

A retrospective analysis was conducted of 37 patients who underwent operations for glioblastoma between 2004 and 2012. Volumetric analysis of postoperative Gd-enhanced MR images, obtained within 48 hours, confirmed tumor gross-total resection (GTR) in all but 2 patients. All patients received the first cycle of TMZ at a dosage of 150 mg/m(2) starting on the second or third postsurgical day. Afterward, patients received concomitant radiochemotherapy according to the Stupp protocol. With regard to adjuvant TMZ therapy, the 19 patients in Group A, aged 30-72 years (mean 56.1 years), received 150 mg/m(2) for 5 days every 28 days for more than 6 cycles (range 7-101 cycles). The 18 patients in Group B, aged 46-82 years (mean 64.8 years), received the same dose, but for no more than 6 cycles. O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status was analyzed for both groups and correlated with overall survival (OS) and progression-free survival (PFS). The impact of age, sex, Karnofsky Performance Scale score, and Ki 67 staining were also considered.

RESULTS

All patients but 1 in Group A survived at least 18 months (range 18-101 months), and patients in Group B survived no more than 17 months (range 2-17 months). The long-term survivors (Group A), defined as patients who survived at least 12 months after diagnosis, were 51.3% of the total (19/37). Kaplan-Meier curve analysis showed that patients treated with more than 6 TMZ cycles had OS and PFS that was significantly longer than patients receiving standard treatment (median OS 28 months vs 8 months, respectively; p = 0.0001; median PFS 20 months vs 4 months, respectively; p = 0.0002). By univariate and multivariate Cox proportional hazard regression analysis, MGMT methylation status and number of TMZ cycles appeared to be survival prognostic factors in patients with glioblastoma. After controlling for MGMT status, highly significant differences related to OS and PFS between patients with standard and long-term TMZ treatment were still detected. Furthermore, in Group A and B, the statistical correlation of MGMT status to the number of TMZ cycles showed a significant difference only in Group A patients, suggesting that MGMT promoter methylation was predictive of response for long-term TMZ treatment. Prolonged therapy did not confer hematological toxicity or opportunistic infections in either patient group.

CONCLUSIONS

This study describes the longest experience so far reported with TMZ in patients with newly diagnosed glioblastomas, with as many as 101 cycles, who were treated using GTR. Statistically significant data confirm that median survival correlates with MGMT promoter methylation status as well as with the number of TMZ cycles administered. Long-term TMZ therapy appears feasible and safe.

miRNA profiling in vitreous humor, vitreal exosomes and serum from uveal melanoma patients: Pathological and diagnostic implications

Uveal melanoma (UM) represents approximately 5-6% of all melanoma diagnoses and up to 50% of patients succumb to their disease. Although several methods are available, accurate diagnosis is not always easily feasible because of potential accidents (e.g., intraocular hemorrhage). Based on the assumption that the profile of circulating miRNAs is often altered in human cancers, we verified whether UM patients showed different vitreous humor (VH) or serum miRNA profiles with respect to healthy controls. By using TaqMan Low Density Arrays, we analyzed 754 miRNAs from VH, vitreal exosomes, and serum of 6 UM patients and 6 healthy donors: our data demonstrated that the UM VH profile was unique and only partially overlapping with that from serum of the same patients. Whereas, 90% of miRNAs were shared between VH and vitreal exosomes, and their alterations in UM were statistically overlapped with those of VH and vitreal exosomes, suggesting that VH alterations could result from exosomal dysregulation. We report 32 miRNAs differentially expressed in UM patients in at least 2 different types of samples analyzed. We validated these data on an independent cohort of 12 UM patients. Most alterations were common to VH and vitreal exosomes (e.g., upregulation of miR-21,-34 a,-146a). Interestingly, miR-146a was upregulated in the serum of UM patients, as well as in serum exosomes. Upregulation of miR-21 and miR-146a was also detected in formalin-fixed, paraffin-embedded UM, suggesting that VH or serum alterations in UM could be the consequence of disregulation arising from tumoral cells. Our findings suggest the possibility to detect in VH and serum of UM patients "diagnostic" miRNAs released by the affected eye: based on this, miR-146a could be considered a potential circulating marker of UM.

Mechanism of action of antidysrhythmic drugs on ventricular conduction as studied with intramural electrodes

Using the Dürrer electrode needle to record the intramural electrogram and a standard peripheral electrocardiogram (ECG) lead as reference, the authors studied the action of 9 different drugs in the conduction system of dogs. The authors concluded that diphenylhydantoin and lignocaine would be useful in dysrhythmias related to increased excitability and perhaps increased automatism. Ajmaline and quinidine may be some of some interest in dysrhythmias due to conduction disturbances; and, finally, ajmaline, diphenylhydantoin, di-isopyramide and quinidine may be useful in dysrhythmias due to focal re-entry.

Diffusion-weighted magnetic resonance imaging and ultrasound evaluation of choroidal melanomas after proton-beam therapy

PURPOSE

This study was undertaken to compare the ultrasound and magnetic resonance imaging parameters of ocular melanoma and to assess their variation after proton-beam therapy.

MATERIALS AND METHODS

Fifteen choroidal melanoma patients treated with proton-beam therapy were enroled in the study. All patients underwent ophthalmologic evaluations, ultrasound, conventional magnetic resonance (MR) imaging and diffusion-weighted MR imaging before the start of therapy and 3 and 6 months after therapy. Basal diameters, thickness, internal reflectivity, tumour volumes and apparent diffusion coefficient (ADC) values of ocular melanomas were measured at each examination. Correlations between internal reflectivity and ADC were investigated.

RESULTS

No significant changes were seen in tumour diameters and tumour height as assessed by B-scan and A-scan, respectively. Significant increase in mean tumour internal reflectivity was detected at 6 months (baseline 35 % ± 11; 6 months 48 % ± 8, Tukey-Kramer p = 0.005). On MRI, compared to baseline (mean 547 ± 262 mm(3)), a significant reduction in volume was seen at 6 months (Tukey-Kramer p = 0.045) (mean volume 339 ± 170 mm(3), mean reduction 38 %). A significant increase in ADC (baseline 1,002 ± 109 mm(2)/s) was detected both at 3 and 6 months after proton therapy (respectively, 1,454 ± 90 and 1,833 ± 261 mm(2)/s, both p < 0.001).

CONCLUSIONS

By MRI, in particular by ADC assessment, it is possible to detect early variations in melanoma treated by proton-beam therapy. This examination could be used together with ultrasound in the follow-up of this treatment.

Diffusion-weighted magnetic resonance imaging for predicting and detecting the response of ocular melanoma to proton beam therapy: initial results

PURPOSE

The aim of this study was to investigate the utility of diffusion-weighted magnetic resonance (MR) imaging for prediction and early detection of response to proton beam therapy in ocular melanoma.

MATERIALS AND METHODS

Ten ocular melanoma patients treated with proton beam therapy were enrolled in the study. All patients underwent conventional MR imaging and diffusion-weighted imaging (DWI) before the start of therapy, and after 1, 3 and 6 months of therapy. Tumour volumes and apparent diffusion coefficient (ADC) values of ocular lesions were measured at each examination. Tumour volumes and mean ADC measurements of the four examination series were compared; correlation of ADC values and tumour regression was investigated.

RESULTS

Mean ADC value of ocular melanomas significantly increased as early as 3 months after therapy; tumour volume significantly decreased as early as 6 months after therapy. The ADC values of ocular melanomas before therapy significantly correlated with tumour regression.

CONCLUSIONS

DWI may provide an early surrogate biomarker for prediction and early detection of tumour response to eye-preserving therapies in ocular melanoma.

Iatrogenic retinal breaks in 25-gauge vitrectomy under air compared with the standard 25-gauge system for macular diseases

PURPOSE

To evaluate the incidence rates of iatrogenic retinal breaks in eyes that underwent 25-gauge vitrectomy under air compared with 25-gauge standard vitrectomy for idiopathic macular holes or idiopathic epiretinal membranes.

METHODS

In this retrospective, comparative interventional study, 435 eyes were enrolled. In all patients after core vitrectomy and epiretinal/inner limiting membrane peeling, complete vitrectomy of the base was performed, respectively under air (air group) or under fluid infusion (standard group).

RESULTS

The number of eyes with iatrogenic retinal breaks was significantly lower in the air group than in standard group (4/197 and 16/238, 2% and 7%, respectively; P = 0.035). A postoperative retinal detachment developed in 2 eyes (1%) in the standard group, and in no eyes of the air group (0%). Factors related to the occurrence of retinal breaks were surgically induced posterior vitreous detachment (P = 0.006), standard vitrectomy (P = 0.023), and surgery for macular hole (P = 0.030).

CONCLUSION

The 25-gauge vitrectomy under air is associated with a lower incidence rate of retinal breaks compared with the standard 25-gauge vitrectomy.

Correlation of preoperative retinal pigment epithelium status with foveal microstructure in repaired macular holes

PURPOSE

To investigate, with spectral-domain optical coherence tomography, if the preoperative status of the retinal pigment epithelium (RPE) affects the postoperative foveal morphology and visual outcomes in eyes with surgically closed macular holes (MHs).

METHODS

In 52 eyes with surgically closed MHs, preoperative RPE morphology was evaluated and graded based on the measurement of the largest hyperreflective protrusions above the RPE line. Foveal microstructural features and best-corrected visual acuity (BCVA) were evaluated 12 months after surgery.

RESULTS

At 12 months, a significant correlation was found between postoperative degree of integrity of the photoreceptors with preoperative RPE morphology, and base diameter of the hole (p = 0.003 and p = 0.028, respectively); mean BCVA at 12 months in eyes with diffuse RPE alteration was significantly lower than in eyes with small or no RPE alteration (p < 0.05).

CONCLUSIONS

Preoperative RPE integrity may be indicative of good photoreceptor restoration and visual recovery in patients with surgically closed MHs.

Radical distributions in ammonium tartrate single crystals exposed to photon and neutron beams

The radiation therapy carried out by means of heavy charged particles (such as carbon ions) and neutrons is rapidly becoming widespread worldwide. The success of these radiation therapies relies on the high density of energy released by these particles or by secondary particles produced after primary interaction with matter. The biological damages produced by ionising radiations in tissues and cells depend more properly on the energy released per unit pathlength, which is the linear energy transfer and which determines the radiation quality. To improve the therapy effectiveness, it is necessary to grasp the mechanisms of free radical production and distribution after irradiation with these particles when compared with the photon beams. In this work some preliminary results on the analysis of the spatial distributions of the free radicals produced after exposure of ammonium tartrate crystals to various radiation beams ((60)Co gamma photons and thermal neutrons) were reported. Electron spin resonance analyses were performed by the electron spin echo technique, which allows the determination of local spin concentrations and by double electron-electron resonance technique, which is able to measure the spatial distance distribution (range 1.5-8 nm) among pairs of radicals in solids. The results of these analyses are discussed on the basis of the different distributions of free radicals produced by the two different radiation beams used.

EPR/alanine pellets with low Gd content for neutron dosimetry

This paper reports on results obtained by electron paramagnetic resonance (EPR) measurements and Monte Carlo (MC) simulation on a blend of alanine added with low content of gadolinium oxide (5 % by weight) to improve the sensitivity to thermal neutron without excessively affecting tissue equivalence. The sensitivity is enhanced by this doping procedure of more an order of magnitude. The results are compared with those obtained with the addition of boric acid (50 % by weight) where boron is in its natural isotopic composition in order to produce low-cost EPR dosemeters. The gadolinium addition influences neutron sensitivity more than the boron addition. The presence of additives does not substantially change the fading of the EPR signal induced by neutrons. The MC simulations agree the experimental results in case of gadolinium addition.

EXAFS and DFT studies on iridium catalysts for SABRE

Since it was first developed, Nuclear Magnetic Resonance (NMR) has become a powerful analytical tool that is now used widely in the fields of chemistry, materials science, and medicine. One way to overcome the intrinsic insensitivity of NMR is to use hyperpolarization techniques to produce non-Boltzmann spin-state distributions. One of these techniques is Signal Amplification By Reversible Exchange (SABRE),[1] in which hyperpolarization is achieved by the temporary association of parahydrogen and a substrate in the coordination sphere of a transition metal. The polarization can be transferred from the parahydrogen-derived hydride ligands to the bound substrate via scalar coupling, followed by dissociation of the hyperpolarized substrate into the bulk solution. We have investigated the efficiency of various iridium NHC complexes with aliphatic and aromatic R groups as SABRE catalysts.[2] The used metal centre is a six-coordinate iridium N-heterocyclic carbene complex, with three substrates and two hydrides, in which the exchange rate of substrate and parahydrogen at the metal centre determines the efficiency of the hyperpolarization. As solvent molecules compete with pyridine for coordination to iridium, the sensitivity of SABRE can be enhanced by displacement of solvent molecules by cosubstrates, i.e. proton-poor ligands such as methyltriazole.[3] In this exchange process, several mixed iridium complexes can be considered to exist, which were not all observed by NMR. Therefore, Density Functional Theory (DFT) calculations were performed on these complexes to better understand this phenomenon. While NMR itself is the best source of information on protons and dynamic processes involved in SABRE, we have found that Extended X-ray Absorption Fine Structure (EXAFS) studies in organic solutions provide interesting complimentary information on the complexes involved.