GLS hyperactivity causes glutamate excess, infantile cataract and profound developmental delay.

Loss-of-function mutations in glutaminase (GLS), the enzyme converting glutamine into glutamate, and the counteracting enzyme glutamine synthetase (GS) cause disturbed glutamate homeostasis and severe neonatal encephalopathy. We report a de novo Ser482Cys gain-of-function variant in GLS encoding GLS associated with profound developmental delay and infantile cataract. Functional analysis demonstrated that this variant causes hyperactivity and compensatory downregulation of GLS expression combined with upregulation of the counteracting enzyme GS, supporting pathogenicity. Ser482Cys-GLS likely improves the electrostatic environment of the GLS catalytic site, thereby intrinsically inducing hyperactivity. Alignment of +/-12.000 GLS protein sequences from >1000 genera revealed extreme conservation of Ser482 to the same degree as catalytic residues. Together with the hyperactivity, this indicates that Ser482 is evolutionarily preserved to achieve optimal-but submaximal-GLS activity. In line with GLS hyperactivity, increased glutamate and decreased glutamine concentrations were measured in urine and fibroblasts. In the brain (both grey and white matter), glutamate was also extremely high and glutamine was almost undetectable, demonstrated with magnetic resonance spectroscopic imaging at clinical field strength and subsequently supported at ultra-high field strength. Considering the neurotoxicity of glutamate when present in excess, the strikingly high glutamate concentrations measured in the brain provide an explanation for the developmental delay. Cataract, a known consequence of oxidative stress, was evoked in zebrafish expressing the hypermorphic Ser482Cys-GLS and could be alleviated by inhibition of GLS. The capacity to detoxify reactive oxygen species was reduced upon Ser482Cys-GLS expression, providing an explanation for cataract formation. In conclusion, we describe an inborn error of glutamate metabolism caused by a GLS hyperactivity variant, illustrating the importance of balanced GLS activity.

INCIDENCE, RISK FACTORS, AND CLINICAL CHARACTERISTICS OF UNEXPLAINED VISUAL LOSS AFTER INTRAOCULAR SILICONE OIL FOR MACULA-ON RETINAL DETACHMENT.

PURPOSE: To investigate the incidence, risk factors, and clinical characteristics of unexplained visual loss after macula-on rhegmatogenous retinal detachment (RRD). METHODS: Retrospective cohort of patients with primary macula-on rhegmatogenous retinal detachment treated by vitrectomy with gas or silicone oil (SO) tamponade in 2011 and 2012. Outcome was unexplained visual loss (>2 Snellen lines) 2 months after the last vitrectomy. RESULTS: Incidence of unexplained visual loss was 0.7% (1/151) in patients treated by gas and 29.7% (11/37) in patients treated by SO (P = 0.001). Visual loss occurred both during SO tamponade and after removal. Cases underwent optical coherence tomography, perimetry, microperimetry, fluorescein angiography, and visual evoked potentials. Patients with unexplained visual loss after SO tamponade showed a small scotoma within the central 2° on microperimetry. Duration of SO tamponade was the only statistically significant factor related to the incidence of unexplained visual loss (P = 0.001). CONCLUSION: Incidence of SO-related visual loss was 30% with duration of tamponade as the only risk factor. This study is the first to apply microperimetry in these patients, which showed a distinct pattern of a small central scotoma. Therefore, microperimetry can be of great value in the diagnostic workup of patients with unexplained visual loss after vitrectomy.

Diagnostic pars plana vitrectomy and aqueous analyses in patients with uveitis of unknown cause.

PURPOSE: To compare the yield of diagnostic pars plana vitrectomy (PPV) with the yield of aqueous analyses in patients with uveitis of unknown cause. METHODS: Seventy-five consecutive patients (84 eyes) with uveitis involving posterior eye segment who undergo a diagnostic PPV from 2005 through 2009 were retrospectively reviewed. Vitreous specimens were simultaneously analyzed by microbiological culture, flow cytometry, and cytology as well as by polymerase chain reaction and for intraocular antibody production by Goldmann-Witmer coefficient. In 53 eyes, both aqueous and vitreous samples were assessed. The primary outcome measure was the comparison between vitreous and aqueous analyses. RESULTS: Vitreous analysis was positive in 18 of 84 eyes (21%). Positive results indicated infectious uveitis in 12 of 18 cases (67%) and lymphoma in 6 of 18 (33%) cases. Of the 53 eyes with both aqueous and vitreous samples available, aqueous analysis revealed the diagnosis in 6 of 53 eyes and vitreous in 9 of 53 eyes. Unilateral uveitis (P = 0.022), panuveitis and uveitis posterior (P ≤ 0.001), preoperative immunosuppressive therapy (P = 0.004), and increasing age (P = 0.018) were associated with an increased diagnostic yield of PPV. Overall, 1 year after PPV, median visual acuity improved from 20/200 to 20/80 (Snellen, P ≤ 0.001). Of 18 patients who were on immunosuppressive treatment before PPV, 8 (44%) were able to stop immunosuppressive therapy during 1-year follow-up. The complications of PPV consisted predominantly of cataract development (33/65, 51%). CONCLUSION: Diagnostic PPV with the analysis of vitreous fluid by multiple laboratories for infectious and malignant disorders was useful in diagnosing uveitis of unknown cause. Previous aqueous analysis was especially valuable for the diagnosis of intraocular infections and may therefore decrease the number of patients who would otherwise undergo an invasive diagnostic PPV. Furthermore, PPV was associated with improved visual acuity and decreased use of immunosuppressive therapy.

Clinical applications for intraoperative optical coherence tomography: a systematic review.

In this systematic review, we provide an overview of the current state of intraoperative optical coherence tomography (iOCT). As iOCT technology is increasingly utilized, its current clinical applications and potential uses warrant attention. Here, we categorize the findings of various studies by their respective fields, including the use of iOCT in vitreoretinal surgery, corneal surgery, glaucoma surgery, cataract surgery, and pediatric ophthalmology. The trend observed in recent decades towards performing minimally invasive ophthalmic surgery has caused practitioners to recognize the limitations of using a conventional surgical microscope for intraoperative visualization. Thus, the superior visualization provided by iOCT can improve the safety of these surgical techniques and promote the development of new minimally invasive ophthalmic surgeries. Landmark prospective studies found that iOCT can significantly affect surgical decision making and can cause a subsequent change in surgical strategy, and the use of iOCT has potential to improve surgical outcome. Despite these advantages, however, iOCT is still a relatively new technique, and beginning users of iOCT can encounter limitations that can preclude their reaching the full potential of iOCT and in this respect several improvements are needed.

Retinal sensitivity following intraocular silicone oil and gas tamponade for rhegmatogenous retinal detachment.

PURPOSE: To investigate whether intraocular silicone oil (SO) tamponade is associated with functional changes in patients with both macula-on and macula-off rhegmatogenous retinal detachments (RRDs). METHODS: Prospective observational cohort study of patients with RRD treated by vitrectomy with gas or SO tamponade at the University Medical Center Utrecht. Outcome was best-corrected visual acuity (BCVA) and retinal sensitivity on microperimetry 2 months after surgery. RESULTS: In total, 40 eyes were included. There are 10 eyes in each of the following groups: macula-on RRD and gas, macula-on RRD and SO, macula-off RRD and gas, and macula-off RRD and SO. Median retinal sensitivity on microperimetry was decreased following SO tamponade compared to gas tamponade for both macula-on and macula-off RRD (p < 0.037). CONCLUSION: Foveal sensitivity was decreased in eyes after SO tamponade compared to gas tamponade. These effects were observed in patients with macula-on as well as macula-off RRD. Although further investigation is warranted to validate our results and to study underlying mechanisms, retinal surgeons need to be aware of these findings after the use of SO tamponade.

A prospective multicentre randomized placebo-controlled superiority trial in patients with suspected bacterial endophthalmitis after cataract surgery on the adjuvant use of intravitreal dexamethasone to intravitreal antibiotics.

PURPOSE: We aimed to determine whether intravitreal dexamethasone as an adjuvant to intravitreal antibiotics is beneficial in the treatment of suspected bacterial endophthalmitis after cataract surgery. METHODS: Randomized, placebo-controlled superiority trial in three tertiary referral centres in the Netherlands. Patients with suspected bacterial endophthalmitis within 6 weeks after cataract surgery were eligible. A diagnostic vitreous biopsy was taken for culture, and patients received intravitreal injections of 400 µg dexamethasone (without preservatives) or placebo, in addition to 0.2 mg vancomycin and 0.05 mg gentamicin. The vancomycin and dexamethasone or placebo injections were repeated once at day 3 or 4. Primary outcome measure was best-corrected visual acuity (BCVA) at 1 year. RESULTS: Between 1 November 2004 and 1 March 2014 (excluding two interruptions totalling 20 months), 324 eligible patients presented. A total of 167 patients (81 dexamethasone, 86 placebo) were available for the intention-to-treat analysis. Biopsies of 114 patients (68%) were culture-positive. Final BCVA did not differ between the dexamethasone and the placebo group (logMAR 0.31 ± 0.58 versus 0.27 ± 0.50; p = 0.90), nor did the number of patients with final vision of no light perception (LP, 7 versus 13). Pain, corneal oedema, the absence of a red fundus reflex on presentation, LP on presentation and culture of virulent pathogens from biopsy were statistically significantly associated with an unfavourable visual outcome. CONCLUSION: Intravitreal dexamethasone without preservatives as an adjuvant to intravitreal antibiotics does not improve visual acuity (VA) in patients treated for suspected bacterial endophthalmitis after cataract surgery.

Electrolyte composition of retro-oil fluid and silicone oil-related visual loss.

PURPOSE: Up to one-third of patients with intra-ocular silicone oil (SO) tamponade for complex macula-on retinal detachment may experience an unexplained visual loss during or after SO tamponade. Although the underlying mechanism is unknown, previous studies suggested that accumulation of retinal potassium could be involved. Hence, this study tested the hypothesis that intra-ocular potassium levels are elevated during SO tamponade. METHODS: A prospective cohort study was carried out from 13 October 2013 through 5 March 2015. Potassium, sodium, magnesium, chloride, calcium, lactate dehydrogenase (LDH) and glucose levels were measured in retro-oil fluid and paired serum from 16 patients undergoing oil removal, including two patients with SO-related visual loss (SORVL). Vitreous humour and paired serum from 27 patients with macular hole (n = 19) or floaters (n = 8) served as controls. RESULTS: Median potassium levels in retro-oil fluid and vitreous humour were similar. Magnesium and chloride levels were lower in retro-oil fluid compared with vitreous humour (p < 0.01) and LDH levels were elevated in retro-oil fluid (p < 0.0001). One of the two patients with SORVL revealed abnormal high potassium and magnesium levels. The other patient had normal levels. CONCLUSION: Potassium levels are not increased in retro-oil fluid during SO tamponade, making the 'potassium accumulation' hypothesis unlikely. The disturbance in magnesium concentration during SO tamponade warrants further investigation.

Ocular Fluid Analysis in Children Reveals Interleukin-29/Interferon-λ1 as a Biomarker for Juvenile Idiopathic Arthritis-Associated Uveitis.

OBJECTIVE: Childhood uveitis is a vision-threatening inflammatory eye disease commonly attributed to juvenile idiopathic arthritis (JIA). The pathogenesis is poorly understood, which makes clinical management challenging. We analyzed soluble mediators in ocular fluid (aqueous humor [AqH]) and serum from children with JIA-associated uveitis and common childhood uveitis to identify potential biomarkers and investigate the ocular microenvironment of this sight-threatening eye disease. METHODS: AqH (n = 73) and paired serum (n = 66) samples were analyzed for 51 soluble mediators of inflammation by multiplex immunoassay. Twenty-one children with JIA-associated uveitis were compared to 15 children with chronic anterior uveitis without arthritis, 29 children with noninfectious idiopathic uveitis, and 8 children with noninflammatory conditions (controls). For visualization of the joint effect of multiple mediators, we used the radial coordinate visualization (Radviz) method. Optimal biomarker level cutoffs were also determined. RESULTS: The levels of interleukin-29 (IL-29)/interferon-λ1 (IFNλ1) were decreased (P < 0.001) and the levels of latency-associated peptide and osteoprotegerin were increased (P = 0.002 and P = 0.001, respectively) in samples of AqH, but not serum, from patients with JIA-associated uveitis. Multivariate analysis correcting for disease activity and treatment revealed that intraocular levels of IL-29/IFNλ1 were specifically decreased in patients with JIA-associated uveitis as compared to those with idiopathic uveitis. Indeed, JIA-associated uveitis patients and idiopathic uveitis patients showed distinct profiles of intraocular soluble mediators. IL-29/IFNλ1 showed a high area under the curve value (0.954), with 23.5 pg/ml as the optimal cutoff value. CONCLUSION: We identified IL-29/IFNλ1 as an intraocular biomarker for JIA-associated uveitis, which suggests that aberrant IFNλ signaling might be important in JIA-associated uveitis and distinct from other forms of childhood uveitis.

Lymphocyte numbers and function in relation to periodontitis and smoking.

BACKGROUND: T and B lymphocytes play important roles in periodontitis. Smoking is considered a risk factor for periodontitis and may exert its negative effects through leukocytes. Taking smoking into consideration, the aim of this study was to analyze numbers of circulating T (CD3+) cells and their CD4+ and CD8+ subpopulations, B (CD19+) cells, and T-cell proliferative capacity in periodontitis. METHODS: Lymphocyte immunophenotyping for T cells, their CD4+ and CD8+ subsets, and B cells was performed on peripheral blood from 76 periodontitis patients and 36 controls. Proliferative capacity of T cells was determined in whole-blood lymphocyte culture assays after mitogenic stimulation. RESULTS: Total T cells, CD4+ and CD8+ subpopulations, and responsiveness to specific T-cell stimuli did not differ between patients and controls; in addition, B cells were not significantly elevated in periodontitis patients. However, more periodontal breakdown in smoking patients was associated with higher numbers of CD3+ T cells, as well as with CD4+ and CD8+ T-cell subsets, and increased T-cell proliferation. Numbers of B cells were not affected by smoking. CONCLUSIONS: The increased numbers of T-cells and elevated T-cell responsiveness in patients who smoke may be one of several explanations why smoking is a risk factor for periodontitis. The mechanism of how T-cell function contributes to increase the severity of periodontal breakdown in smoking periodontitis patients needs to be investigated further.

Detection of choroid- and retina-antigen reactive CD8(+) and CD4(+) T lymphocytes in the vitreous fluid of patients with birdshot chorioretinopathy.

Birdshot chorioretinopathy (BSCR), a progressive form of non-infectious uveitis, is the strongest HLA-associated disease described to date, with >95% of the patients displaying HLA-A29. Since indirect evidence indicates the involvement of T cells in the etiopathology of the disease, we now isolated, cultured and analyzed the vitreous fluid-infiltrating T cells from two BSCR patients with respect to their phenotype, cytokine profile, clonal distribution and antigen specificity. Phenotypic analyses revealed the predominant presence of both CD4(+) and CD8(+) T cells in vitreous fluid. Further analyses on short term expanded and cloned T cells suggested that eye-infiltrating T cells generally displayed a Th1 like cytokine profile with secretion of high levels of IFN-γ and TNF-α. In one patient an oligoclonal CD4(+) and CD8(+) T cell infiltration, with a moderate to strongly skewed TCR Vß usage was suggestive for an antigen driven infiltration/expansion. Indeed, a number of intraocular CD4(+) and CD8(+) T cells responded to crude retinal and choroidal lysates. These results, which demonstrate for the first time the existence of eye-antigen-specific T cells in the vitreous fluid of BSCR patients, substantiate the current view on the role of eye-antigen specific T cells in the etiopathology of BSCR.

Intraocular biomarker identification in uveitis associated with juvenile idiopathic arthritis.

PURPOSE: To investigate the presence of biomarkers in aqueous humor (AH) from patients with uveitis associated with juvenile idiopathic arthritis (JIA). METHODS: AH (N = 73) AND SERUM (N = 105) SAMPLES FROM 116 CHILDREN WERE ANALYZED USING SURFACE ENHANCED LASER DESORPTION/IONIZATION TIME OF FLIGHT MASS SPECTROMETRY (SELDI-TOF MS). THE SAMPLES WERE DIVIDED INTO THE FOLLOWING GROUPS: JIA, silent chronic anterior uveitis (AU), other uveitis entities, and noninflammatory controls. Statistical biomarker identification was performed using the SELDI-ToF Biomarker Analysis Cluster Wizard followed by multivariate statistical analysis. Biochemical identification of biomarkers was performed by polyacrylamide gel protein separation, followed by liquid chromatography tandem mass spectrometry. ELISA was performed in a number of AH samples representing all four study groups. RESULTS: In the JIA group, one AH protein peak at mass/charge (m/z) 13,762 had qualitative and quantitative differences in expression compared with the other uveitis entities and the controls, but not to the group of silent chronic AU. Its quantitative expression in AH of patients with JIA and other silent chronic AU was positively associated with uveitis activity. The protein at m/z 13,762 in AH was identified as transthyretin (TTR). The TTR concentration in AH differed significantly between the study groups (P = 0.006) with considerably higher TTR concentrations in JIA and silent chronic AU samples positive for m/z 13,762 than those of the other uveitis and control groups. CONCLUSIONS: TTR is a potential intraocular biomarker of JIA- associated uveitis. Its role in the pathogenesis of silent chronic AU with and without arthritis needs further investigation.

Innovation in Namibia: preserving private health insurance and HIV/AIDS treatment.

Namibia, a lower-middle-income country in sub-Saharan Africa, suffers from a huge HIV/AIDS burden. An influx of donor funding in 2004-2007 increased support for publicly provided HIV care and treatment. This raised concern that private funding would be "crowded out," thereby leading to a reduction in the overall resources used to treat patients. In 2006 the Namibian medical aid industry, with donor support, created a special fund to subsidize private health insurance, including HIV/AIDS services. The program allowed both low- and higher-income people to be covered. Crowding out valuable private resources was avoided and the quality of HIV/AIDS services improved.

Cytokines, chemokines and soluble adhesion molecules in aqueous humor of children with uveitis.

Uveitis in childhood is a visual threatening disease with a complication rate of more than 75%. Despite extensive research, the etiology of uveitis is still unclear although the general opinion is now that uveitis is a T-cell mediated disease. The purpose of this study was to investigate the profile of cytokines, chemotactic cytokines (chemokines) and soluble adhesion molecules in the aqueous humor (AqH) of children with uveitis in order to identify the factors that control the immune response in the eye. In this clinical laboratory investigation we analyzed, with a multiplex immunoassay, 16 immune mediators in the AqH of 25 children with uveitis and 6 children without uveitis. Increased levels of interleukin-2 (IL-2), IL-6, IL-10, IL-13, IL-18, interferon-gamma, tumor necrosis factor-alpha, soluble intercellular adhesion molecule-1, RANTES, IL-8 and interferon-inducible 10-kDa protein were found in the AqH of children with uveitis compared with controls. No significant differences were found for IL-1 beta, IL-4, IL-12 p-70, soluble vascular cell adhesion molecule 1 and Eotaxin. Lower levels of IL-10 and IL-8 were found in quiet stage uveitis (surgical) samples compared with active uveitis (diagnostic) samples and in samples of patients treated with methotrexate (MTX) compared with samples of patients not treated with MTX. Lower levels of IL-10 were as well found in samples taken during the first 3 months after the diagnosis of uveitis than samples taken later during the disease process. No significant differences were found between patients treated with or without topical or systemic (perioperative and long term) corticosteroids. In conclusion, in children with uveitis, multiple intraocular cytokines, chemokines and soluble adhesion molecules are increased in the AqH regardless of active or inactive inflammation. Whether the IL-8 and IL-10 levels in AqH of children with uveitis are correlated with uveitis activity, early or late phase of the course of the disease and systemic treatment with MTX needs further investigation in a bigger study population.

Suppression extends to major histocompatibility antigens linked to tolerizing minor histocompatibility antigens, but not the other way round.

'Active suppression', a mechanism of transplantation tolerance, can spread to newly introduced minor antigens once these antigens are linked to tolerizing antigens. We explored whether this suppression can extend to major histocompatibility (MHC) antigens and whether this phenomenon can be demonstrated once tolerance is induced to a MHC antigen. Mice were tolerized using donor bone marrow plus CD4 and CD8 monoclonal antibodies. The following strain combinations were used: AKR (H-2k) into CBA (H-2k), a multiple minor difference and B6 (H-2b) into B6(bm12) (H-2b), a MHC class II difference. Tolerance was tested by a donorskingraft. CBA mice tolerant to AKR received a second skin carrying either AKR antigens plus additional multiple minor antigens [F1(AKRxBalb.K)] or carrying additional minors and a MHC class I antigen (B10.AKM-H2M). B6(bm12) (H-2b) tolerant to B6 (H-2b) were grafted with skin from a Balb.B donor (Balb minors linked to the tolerizing class II antigen) or from a B10.A(3R) strain (a MHC class I antigen linked to the tolerizing class II antigen). CBA mice tolerant to AKR accepted F1(AKRxBalb.K) skin, whereas F1(CBAxBalb.K) were rejected. Rejection of B10.AKM/H2M skin by tolerant mice was delayed as compared with nontolerant mice. Tolerant and nontolerant B6(bm12) mice rejected Balb.B skin and B10.A(3R) skin within the same time. Thus, in this model, suppression was linked to minors. Alloreactivity against minors and majors could be suppressed. Suppression linked to a class II antigen could not be demonstrated.

Memory functions in prednisone-treated kidney transplant patients.

The literature indicates that high daily doses of gluco-corticosteroids have a degenerating effect upon the hippocampus and thus result in reduced declarative memory capacities. In order to prevent rejection, renal transplant recipients are treated with moderate daily doses of gluco-corticosteroids and, if necessary, with high pulse-doses during a few days. The question, therefore, arises as to whether or not such standard treatments result in memory impairments. For this reason, declarative memory capacities were measured, by means of a Dutch version of Rey's 15 Words Test, in a group of 52 renal transplant recipients. Results clearly indicated severe reductions in declarative memory capacities in these patients.

Immune responsiveness in renal transplant recipients: mycophenolic acid severely depresses humoral immunity in vivo.

BACKGROUND: Current immunosuppressive drug treatments for renal transplant recipients result in high one-year graft survival rates. Despite adequate suppression of the immune response directed to the allograft, the immune system remains able to cope with many infectious agents. METHODS: To define the influence of distinct immunosuppressive treatment protocols, primary and secondary cellular and humoral immune responses in groups of renal transplant recipients were studied: patient treated with prednisolone and cyclosporine A (P/CsA); with IgA CD3 monoclonal antibody as a rejection treatment superimposed on prednisolone and cyclosporine A (IgA CD3 mAb+P/CsA); and with prednisolone, cyclosporine A and mycophenolate mofetil (P/CsA/MMF). RESULTS: Primary in vitro proliferative responses to the protein antigen keyhole limpet hemocyanin (KLH) were not significantly disturbed in P/CsA treated patients, or in IgA CD3 mAb+P/CsA and P/CsA/MMF treated patients. In vitro proliferative responses to the recall antigen tetanus toxoid (TT) were similarly unaffected. Antigen-specific antibody responses to immunization with KLH and TT were not affected by treatment with P/CsA, or by IgA CD3 mAb+P/CsA, but were severely disturbed in patients treated with P/CsA/MMF. All patients displayed a profound inhibition of the delayed-type hypersensitivity skin reactivity to KLH and recall antigens. Nevertheless, in most patients with P/CsA treatment, T cell infiltrates were observed in skin biopsies from the site of KLH challenge, while expression of intercellular cell adhesion molecule-1 (ICAM-1) expression in challenged skin was significantly decreased in these patients. The balance between T helper 1 and T helper 2 cells was unaffected by immunosuppressive treatments during one year of follow-up. CONCLUSIONS: Immunosuppressive drug treatment with P/CsA inhibits delayed-type hypersensitivity skin reactions to both primary and frequently encountered antigens. Histological studies indicate an effect on ICAM-1 expression, leaving the influx of CD3pos T cells unaffected. Administration of a 10-day course of IgA CD3 mAb does not add profound immunosuppressive effects on the measured parameters. In contrast, addition of treatment with MMF profoundly decreases both primary and secondary humoral immune responsiveness in vivo. Finally, no effect of the studied immunosuppressive drugs on Th1/Th2 balance in vivo was measured.