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Background: Leber hereditary optic neuropathy (LHON) is a rare but bilaterally blinding disease. Three characteristic disease-causing point mutations, and other less common mutations, are most often found on the mitochondrially encoded genes of NADH-ubiquinone oxidoreductase core subunits (MT-ND). The purpose of this study is to provide an overview of LHON mutations in Southwestern Ontario and to describe the associated demographic and clinical characteristics. Methods: A retrospective genetic and clinical chart review was performed from January 2015 to 2020. Patients were identified within a mitochondrial mutation database and included if a mutation was detected on the MT-ND1, -ND4, or -ND6 genes. A clinical chart review was done on all available patients. Results: Forty-five of 63 patients identified had classic disease-causing mutations (6.7% m.3460G>A, 44.4% m.11778G>A, and 48.9% m.14484T>C). Several of the remaining 18 patients had rare mutations previously documented in association with LHON. Of the 14 patients with clinical charts accessible for review, 12 had symptomatic disease, and all but one had bilateral optic neuropathies. Nine patients had classic LHON mutations and 3 had possible novel mutations; 7 were males; 9 had final visual acuity ≤ 20/200 in at least one eye; and 6 of those had ≤20/400 in both eyes. Conclusions: This study adds to the literature on LHON in Canada, and specifically Southwestern Ontario. The demographic and clinical data regarding LHON in this geographic location, as well as possible novel disease-causing mutations, provide important information to aid clinicians in recognizing cases of LHON that may otherwise be disregarded.

PURPOSE To determine whether optical coherence tomography angiography is of diagnostic utility for Susac syndrome (SuS) by quantifying microvascular retinal changes. METHODS We enrolled 18 eyes of 9 healthy controls and 18 eyes of 9 patients with chronic SuS (12 had previous branch retinal artery occlusions and 6 were clinically unaffected). Images of the fovea were taken using an optical coherence tomography angiography system. Analysis included vessel density, fractal dimension, vessel diameter, and measurements of the foveal avascular zone (area, eccentricity, acircularity index, and axis ratio) in deep and superficial retinal layers. RESULTS Skeleton density and inner ring vessel density were significantly lower in patients with SuS (skeleton density: Susac 0.11 ± 0.01 vs. controls 0.12 ± 0.01, P = 0.027. VD: SuS 0.39 ± 0.04 vs. controls 0.42 ± 0.02, P = 0.041). Eccentricity and axis ratio were significantly higher in patients with SuS (EC: Susac 0.61 ± 0.11, controls 0.51 ± 0.10, P = 0.003; axis ratio: Susac 1.57 ± 0.28, controls 1.39 ± 0.11, P = 0.005). SuS eyes (affected and unaffected) had poorer outcomes of the remaining vascular parameters compared with controls (P > 0.05). CONCLUSION Optical coherence tomography angiography identified chronic microvascular changes in the eyes of patients with chronic SuS. Even clinically unaffected SuS eyes showed poorer vascular parameters. Although further research is needed, this noninvasive imaging modality seems to have the potential to serve as a valuable additive diagnostic tool.

Background and purpose There is a lack of comparative safety data on the risk of pseudotumor cerebri syndrome (PTCS) associated with different hormonal contraceptives. We sought to quantify the risk of PTCS associated with eight different types of hormonal contraceptives compared with oral levonorgestrel. Methods We conducted a retrospective cohort study, with a case-control analysis of 4 871 504 women aged 15-45 years in the period 2008-2015, using IQVIA Ambulatory Electronic Medical Records data in the USA. Patients who used nine different contraceptive agents including intrauterine levonorgestrel, medroxyprogesterone injection, etonogestrel/ethinyl estradiol vaginal ring and combination oral contraceptives (COCs) that contained ethinyl estradiol and the progestins levonorgestrel, norgestimate, desogestrel, norethindrone and drospirenone, were included. Diagnosis of PTCS was defined using the first International Classification of Diseases, 9th or 10th revision, code for intracranial hypertension in patients who had also received an imaging code in the 30 days prior to the index date. Results A total of 3323 PTCS cases and 13 292 matched controls were identified. No increase in risk was found when analysing intrauterine levonorgestrel or COCs containing desogestrel, norethindrone, drospirenone, norgestimate or norgestrel versus COC levonorgestrel. The adjusted incidence rate ratio for etonogestrel/etonogestrel/ethinyl estradiol vaginal ring and medroxyprogesterone suspension compared with levonorgestrel COC was 4.45 [95% confidence interval (CI) 1.98-9.96] and 2.20 (95% CI 1.33-3.64), respectively. Conclusions This study found an elevated risk for PTCS among users of etonogestrel vaginal ring and medroxyprogesterone suspension when compared with oral levonorgestrel. Future studies are needed to confirm these findings.

In recent years, the substantial burden of medical comorbidities in autism spectrum disorder (ASD) populations has been described. We report a retrospective observational case series of pediatric patients with suspected idiopathic intracranial hypertension (IIH) and concurrent ASD. Pediatric subjects with suspected IIH aged 2–18 years were identified by review of a pediatric neuro-ophthalmologist’s database spanning from July 1993 to April 2013. ASD diagnoses were identified within this cohort by an ICD-9 diagnosis code search and database review. Three subjects had concurrent ASD diagnoses, all were non-obese males. Since the retrospective observational case series was performed in April 2013, we identified three additional IIH cases in boys with ASD. Our experience suggests that IIH may be a comorbidity of ASD, particularly in non-obese boys.

Background Revised diagnostic criteria for pseudotumor cerebri syndrome require three of four neuroimaging findings in the absence of papilledema. We examined the sensitivity and specificity of three or more of four of these magnetic resonance imaging (MRI) findings for pseudotumor cerebri syndrome in children. Methods As part of clinical care, patients in whom there was suspicion for pseudotumor cerebri syndrome underwent neurological and fundoscopic examinations, lumbar puncture, MRI, or magnetic resonance venogram. For this retrospective study, we used this information to classify 119 subjects into definite (n = 66) or probable pseudotumor cerebri syndrome (n = 12), elevated opening pressure without papilledema (n = 23), or controls who had normal opening pressure without papilledema (n = 24). A neuroradiologist, unaware of the clinical findings or original MRI report, reviewed MRIs for pituitary gland flattening, flattening of the posterior sclera, optic nerve sheath distention, and transverse venous sinus stenosis. Results The presence of three or more MRI findings has a sensitivity of 62% (95% confidence interval: 47% to 75%) and a specificity of 95% (95% confidence interval: 77% to 100%), compared with controls. Two of three (transverse venous sinus stenosis, pituitary gland flattening, flattening of the posterior sclera) had a similar sensitivity and specificity. Transverse venous sinus stenosis alone had a slightly higher sensitivity (74%, 95% confidence interval: 60% to 85%) and specificity (100%, 95% confidence interval: 80% to 100%). Conclusions In children, three of four of the proposed neuroimaging criteria and transverse venous sinus stenosis alone have a moderate sensitivity and robust specificity for pseudotumor cerebri syndrome. MRIs should be reviewed for these criteria, and their presence should raise suspicion for pseudotumor cerebri syndrome in children, particularly if the presence of papilledema is uncertain.

Purpose To develop and validate neural network (NN) vs logistic regression (LR) diagnostic prediction models in patients with suspected giant cell arteritis (GCA). Design: Multicenter retrospective chart review. Methods An audit of consecutive patients undergoing temporal artery biopsy (TABx) for suspected GCA was conducted at 14 international medical centers. The outcome variable was biopsy-proven GCA. The predictor variables were age, gender, headache, clinical temporal artery abnormality, jaw claudication, vision loss, diplopia, erythrocyte sedimentation rate, C-reactive protein, and platelet level. The data were divided into three groups to train, validate, and test the models. The NN model with the lowest false-negative rate was chosen. Internal and external validations were performed. Results Of 1,833 patients who underwent TABx, there was complete information on 1,201 patients, 300 (25%) of whom had a positive TABx. On multivariable LR age, platelets, jaw claudication, vision loss, log C-reactive protein, log erythrocyte sedimentation rate, headache, and clinical temporal artery abnormality were statistically significant predictors of a positive TABx (P≤0.05). The area under the receiver operating characteristic curve/Hosmer-Lemeshow P for LR was 0.867 (95% CI, 0.794, 0.917)/0.119 vs NN 0.860 (95% CI, 0.786, 0.911)/0.805, with no statistically significant difference of the area under the curves (P=0.316). The misclassification rate/false-negative rate of LR was 20.6%/47.5% vs 18.1%/30.5% for NN. Missing data analysis did not change the results. Conclusion Statistical models can aid in the triage of patients with suspected GCA. Misclassification remains a concern, but cutoff values for 95% and 99% sensitivities are provided (https://goo.gl/THCnuU).

Moyamoya (MM) disease is a chronic cerebrovascular disease that can lead to progressive stenosis of the terminal portions of the internal carotid arteries and their proximal branches. We sought to investigate and quantify retinal vascular changes in patients with MM vasculopathy (MMV) using optical coherence tomography angiography (OCTA) compared to healthy controls. Our findings reveal retinal microvascular changes in patients with MMV and highlights the potential of OCTA imaging for the detection of subclinical retinal pathology.

Recent data suggests that herpes zoster (HZ) and herpes simplex virus (HSV) may be one of the underlying immunological triggers for giant cell arteritis (GCA). However, there is limited population-based data to support this. Our goal was to determine if herpetic infections increase the likelihood of GCA in the British Columbia (BC) population. The background prevalence of GCA was compared to the prevalence of GCA in subjects with HZ and HSV using diagnostic billing code data from an online BC database (BC Data ScoutTM). BC residents &ge, 30 years old at the time of diagnosis from January 2000 to January 2019 were included. The relevant International Classification of Disease codes was used to identify patients with GCA, HZ, and HSV. Comparisons were made using two-sample Z tests. There were 4315 GCA diagnoses, from a total population of 3,026,005 subjects. The prevalence of GCA was 143 per 100,000 people. In terms of herpetic infections, 850 GCA cases were identified in 249,900 subjects with HZ versus 310 diagnoses of GCA in 163,170 subjects with HSV. The prevalence of GCA in subjects with HZ (0.340%) was significantly higher than the prevalence of GCA (0.143%) in the general population (p &lt, 0.00001). The prevalence of GCA in HSV subjects (0.190%) was also significantly higher (p &lt, 0.00001) than the population prevalence but lower than (p &lt, 0.00001) the GCA with HZ prevalence. The likelihood of GCA appears to increase with herpetic infections, more significantly with HZ.

Background The purpose of this study was to determine the prognostic utility of closing pressure and volume of cerebrospinal fluid removed with respect to papilledema resolution and headache improvement in pediatric pseudotumor cerebri syndrome. Methods This is a retrospective observational study of 93 children with definite pseudotumor cerebri syndrome. The primary outcome measure was time to resolution of papilledema, and the secondary outcome measure was time to resolution of headache. Results There were no significant differences in gender, age, or body mass index z score observed between subjects with (N = 35) and without (N = 58) documented closing pressure. The median time to resolution of papilledema was not statistically different between children above or equal to and those below the median closing pressure (170 mm of cerebrospinal fluid, n = 31, P = 0.391) or the volume of median cerebrospinal fluid removed (16 mL, n = 19, P = 0.155). There was no statistically significant difference detected in days of headache between the children with opening pressure above and equal to the median (400 mm of cerebrospinal fluid) and the children with opening pressure below the median (n = 44, P = 0.634). Conclusions No significant association between closing pressure, amount of cerebrospinal fluid removed, and time to resolution of papilledema due to pseudotumor cerebri syndrome was detected. The diagnostic and therapeutic purposes of either measuring the closing pressure or maximizing the volume of cerebrospinal fluid removed were not evident in these analyses.

Idiopathic intracranial hypertension, otherwise known as primary pseudotumor cerebri syndrome (PTCS), most frequently occurs in obese women of childbearing age. However, children may be affected as well. This review will address recent findings regarding demographics, diagnosis, and treatment of pediatric PTCS. Prepubertal children with primary PTCS have an equal sex distribution and less frequent obesity compared with adult patients. However, female gender and obesity are risk factors for primary PTCS in postpubertal children. Compared with adults, children with PTCS more frequently present with ocular motility deficits and more often have associated medical conditions that increase the risk of developing PTCS. Visual field testing may be unreliable, and the optimal modality to monitor visual function is unknown. MRI shows signs of elevated intracranial pressure (ICP) in children with PTCS similar to that of adults. It has now been established that elevated ICP in children ≤18 years old is greater than 25 cm H20 in nonobese, nonsedated children, and greater than 28 cm H2O in the remainder. Optical coherence tomography (OCT) may be used to distinguish pseudopapilledema from papilledema, monitor response to treatment in preverbal children, and identify patients with PTCS at risk for permanent visual loss. However, the precise role of OCT in the management of pediatric PTCS remains to be determined.

Objective:To quantify the risk of secondary pseudotumor cerebri syndrome (PTCS) with fluoroquinolones.Methods:A case-control study of people 15–60 years of age from the LifeLink Database (QuintilesIMS, Parsippany, NJ) was conducted. Cases had the first ICD-9-CM code for benign intracranial hypertension (BIH) as well as having received a procedure code for an MRI or CT scan and a lumbar puncture within 15 days or 30 days of the BIH code. For each case, 10 controls were selected using density-based sampling. Current users of fluoroquinolones received a prescription within 15 days or 30 days of the date of the diagnosis. For the sensitivity analysis, risk periods for 30 and 60 days were also examined. Adjusted rate ratios (RRs) were computed from a conditional logistic regression model.Results:From a cohort of 6,110,723 people, there were 339 cases of PTCS and 3,390 corresponding controls. In the primary analysis, the adjusted RR for current users of fluoroquinolones for both the 15-day and 30-day definitions were 5.67 (95% confidence interval [CI] 2.72–11.83) and 4.15 (95% CI 2.29–7.50), respectively. The risk with tetracycline antibiotics was also increased, with RRs for 15 and 30 days of current use of 2.68 (0.89–8.11) and 3.64 (1.67–7.91), respectively.Conclusion:Our study suggests an increase in the risk of PTCS with current users of fluoroquinolones. Although this adverse event is rare, patients who experience symptoms of raised intracranial pressure including headaches, tinnitus, and double vision while taking fluoroquinolones should seek medical attention.

Objective To evaluate whether corpus callosum (CC) lesions are inextricably linked to CNS symptoms of Susac Syndrome (SuS) by reviewing published cases to find instances where: 1) CC lesions occur without CNS symptoms, and 2) whether patients with CNS symptoms lack CC lesions. Methods 100 reported cases of SuS were identified in PubMed. Clinical symptoms, para-clinical testing and MRI data were collected both at presentation and for any available follow-up and analyzed. Cases were reviewed to evaluate how they met European diagnostic criteria for SuS (EuSaC) both at first presentation and at most recent evaluation after followup, if available. Results Limited disease is a common finding in the 100 recently published cases and 56/100 cases did not meet EuSaC probable or definite criteria at first evaluation. CC lesions were not inextricably linked with encephalopathy, as 8 cases presented with CC lesions without CNS symptoms and 6 cases had encephalopathy without CC lesions. In five patients with both eye and ear involvement, isolated CC lesions or CNS symptoms could enhance diagnostic certainty. This may reduce specificity, but would increase sensitivity, ultimately benefitting patient care. Conclusion Patients with early SuS rarely meet diagnostic criteria at presentation. Future diagnostic criteria could make use of unlinked CC lesions or CNS symptoms.

Purpose To examine anthropometric and maturational characteristics at diagnosis in pediatric idiopathic intracranial hypertension (IIH). Design Retrospective, international, multisite study. Participants Pediatric patients (2–18 years of age at diagnosis) with IIH. Main Outcome Measures Body mass index (BMI), height, and weight Z-scores; sexual maturation. Methods Cases of IIH were identified retrospectively based on diagnostic code, pediatric neuro-ophthalmologist databases, or both and updated diagnostic criteria (2013) were applied to confirm definite IIH. Anthropometric measurements were converted into age- and gender-specific height, weight, and BMI Z-scores CDC 2000 growth charts. When available, sexual maturation was noted. Results Two hundred thirty-three cases of definite IIH were identified across 8 sites. In boys, a moderate association between age and BMI Z-scores was noted (Pearson's correlation coefficient, 0.50; 95% confidence interval [CI], 0.30–0.66; P P P = 0.002 in girls and P = 0.02 in boys). Data on Tanner staging, menarchal status, or both were available in 25% of cases (n = 57/233). Prepubertal participants (n = 12) had lower average BMI Z-scores (0.95±1.98) compared with pubertal participants (n = 45; 1.92±0.60), but this result did not reach statistical significance ( P = 0.09). Conclusions With updated diagnostic criteria and pediatric-specific assessments, the present study identifies 3 subgroups of pediatric IIH: a young group that is not overweight, an early adolescent group that is either overweight or obese, and a late adolescent group that is mostly obese. Data also suggest that the early adolescent group with IIH may be taller than age- and gender-matched reference values. Understanding these features of pediatric IIH may help to illuminate the complex pathogenesis of this condition.

An infant presented with bilateral disk edema and an acute left sixth cranial nerve (CN VI) palsy because of pseudotumor cerebri (PTC). PTC is rare in infants where it is often associated with endocrine abnormalities, medications, viral infections, systemic conditions, and nutritional etiologies such as vitamin A toxicity. We report a case of PTC in an infant associated with hypervitaminosis A with an unlikely source-a common prenatal vitamin.

ObjectiveTo determine the temporal evolution, morphology, and frequency of macular ganglion cell atrophy in patients with retrochiasmal lesions of the visual pathway.MethodsIn a consecutive retrospective case series, we identified 47 patients with homonymous hemianopia and accessible macular optical coherence tomography scans. We estimated the time of lesion onset and the location of the lesion within the afferent visual pathway. Using semiautomatic layer segmentation, we determined ganglion cell layer thickness in areas projecting to the side of the retrochiasmal lesion and compared it with ganglion cell layer thickness on the healthy side.ResultsWe found that retrochiasmal lesions at any level may be associated with an atrophy of ganglion cells. This atrophy respects the vertical midline through the fovea and thus the anatomic separation of the nasal and temporal visual field. The vertical line separating the affected from the unaffected side has significantly less tilt as compared with the disc–fovea angle. Lesions of the optic tract are associated with earlier macular ganglion cell atrophy than retrogeniculate lesions. Macular ganglion cell atrophy may be present in cases with normal peripapillary nerve fiber layer analysis and vice versa.ConclusionsMacular ganglion cell layer thickness shows a topographic hemiatrophy in retrochiasmal lesions, which manifests earlier for tract lesions than for retrogeniculate lesions. This additional examination of ganglion cell homonymous hemiatrophy has a higher sensitivity in detecting retrograde transsynaptic degeneration than the analysis of the peripapillary nerve fiber layer alone.

Pseudotumor cerebri syndrome (PTCS) is defined by the presence of elevated intracranial pressure in the setting of normal brain parenchyma and cerebrospinal fluid. PTCS can occur in the pediatric and adult populations and, if untreated, may lead to permanent visual loss. In this review, discussion will focus on PTCS in the pediatric population and will outline its distinct epidemiology and key elements of diagnosis, evaluation and management. Finally, although the precise mechanisms are unclear, the underlying pathophysiology will be considered.

Pseudotumor cerebri syndrome (PTCS) is defined by the presence of elevated intracranial pressure in the context of normal brain parenchyma and normal cytologic and chemical analyses of the cerebrospinal fluid. The presenting signs and symptoms of PTCS are various and usually include headache, papilledema, and visual disturbances (e.g., vision loss, double vision). Idiopathic intracranial hypertension, which is the primary form of PTCS, generally affects postpubertal overweight women of childbearing age. Secondary PTCS refers to a clinical diagnosis of PTCS attributable to one or more of a variety of identifiable causes, including venous sinus thrombosis, medications, and medical conditions other than obesity alone. The diverse clinical spectrum of pediatric PTCS is becoming increasingly recognized and recent research in this field is aiming to identify a common pathophysiology. We hereby review the recent diagnostic criteria and classification of pediatric PTCS.

Background Certain headache characteristics and associated symptoms are commonly attributed to increased intracranial pressure, but they have not been systematically studied among children in the context of revised diagnostic criteria for pseudotumor cerebri syndrome (PTCS). Methods We performed a retrospective cohort study of patients treated for suspected or confirmed PTCS. Charts were reviewed for PTCS and headache diagnostic criteria and associated characteristics. Chi-squared or Fisher's exact tests were used to compare the frequency of headache characteristics between groups. Results One hundred and twenty-seven individuals were identified: 61 had definite PTCS, 10 had probable PTCS, 31 had elevated opening pressure (OP) without papilledema, and 25 had normal OP without papilledema. Eleven children had no headache (6 with definite PTCS, 5 with probable PTCS). Headache pattern was episodic in 49% (95% CI: 34-64%) of those with definite PTCS, 18% (95% CI 6-37%) of those with elevated OP without papilledema, and 16% (5-36%) of those with normal OP without papilledema. Headache location was more likely to involve the head along with neck or shoulders in those with definite PTCS compared with elevated OP without papilledema (OR = 7.2, 95% CI: 1.9-27.6) and normal OP (OR = 4.5, 95% CI: 1.3-15.6) groups. Discussion While missing data and small cohort size are limitations, this study suggests that headache in PTCS is more likely to involve the head along with neck/shoulders, and that headache in PTCS may be episodic or constant. Headache is occasionally absent in PTCS.

Objectives The objectives of the present study were: (i) to examine the leading clinical indications and pathologic diagnoses of penetrating keratoplasties in Vancouver, BC; and (ii) to evaluate the correlation between the clinical and pathologic diagnoses. Design Retrospective chart review of all pathologic records of corneal tissue submitted to the Department of Pathology & Laboratory Medicine, Vancouver General Hospital, during an 11-year period. Methods For each penetrating keratoplasty, information regarding the clinical indication and pathologic features identified on histopathologic analysis was compiled. Results The top 5 clinical indications for transplant were failed graft (21%); bullous keratopathy (20%); keratoconus (17%); scarring, with or without inflammation (14%); and Fuchs dystrophy (11%). The top 5 pathologic diagnoses corresponded to these clinical diagnoses. In the majority of cases, there was agreement between clinical and pathologic diagnoses; however, in 6% of records, the clinical and pathologic diagnoses did not correlate. This situation occurred most often when considering grafts with clinical diagnoses of bullous keratopathy, Fuchs dystrophy, or keratoconus. A review of the grafts with infectious keratitis illustrated the potential for histopathologic evaluation of corneal buttons to identify unsuspected infectious agents. Conclusion Routine histopathologic evaluation of penetrating keratoplasty clarifies the clinical diagnosis in a proportion of cases and aids in identifying infectious agents.

Purpose: Vitamin A deficiency is a very rare condition in the developed world and can lead to a variety of ocular changes from xerosis and xerophthalmia to corneal ulcer and perforation. The treatment of this devastating disease is simple and inexpensive. It is therefore important to recognize and treat accordingly, especially in the event of ulcers unresponsive to treatment or in the presence of severe malnutrition/malabsorption syndromes. The purpose of this case report is to remind physicians of the potentially devastating effects of vitamin A deficiency on the eyes and to demonstrate outcomes after vitamin A treatment. Methods: Single observational case report. Results: A 29-year-old male with known eosinophilic gastroenteropathy was treated with oral steroids for peripheral ulcerative keratitis. Two weeks after resolution, the patient suffered from peripheral ulcerative keratitis in his other eye, with a self-sealing perforation. Vitamin A deficiency was confirmed and successfully treated, leading to subsequent resolution of signs and symptoms. Conclusions: Vitamin A deficiency can be present in patients with malabsorption and malnutrition syndromes and should be considered as cause of corneal ulceration.

The reading of text is predominantly a left hemisphere function. However, it is also possible to process text for attributes other than word or letter identity, such as style of font or handwriting. Anecdotal observations have suggested that processing the latter may involve the right hemisphere. We devised a test that, using the identical stimuli, required subjects first to match on the basis of word identity and second to match on the basis of script style. We presented two versions, one using various computer fonts, and the other using the handwriting of different individuals. We tested four subjects with unilateral lesions who had been well characterized by neuropsychological testing and structural and/or functional MRI. We found that two prosopagnosic subjects with right lateral fusiform damage eliminating the fusiform face area and likely the right visual word form area were impaired in completion times and/or accuracy when sorting for script style, but performed better when sorting for word identity. In contrast, one alexic subject with left fusiform damage showed normal accuracy for sorting by script style and normal or mildly elevated completion times for sorting by style, but markedly prolonged reading times for sorting by word identity. A prosopagnosic subject with right medial occipitotemporal damage sparing areas in the lateral fusiform gyrus performed well on both tasks. The contrast in the performance of patients with right versus left fusiform damage suggests an important distinction in hemispheric processing that reflects not the type of stimulus but the nature of processing required.

Background: Hormonal contraceptives (HC), one of the most prescribed classes of medication in women, have been linked with pseudotumor cerebri syndrome (PTCS). To date, no large epidemiologic study has examined this association.Methods: A case-control study using the IMS LifeLink Pharmetrics Plus database was conducted. Cases had an ICD-9-CM code for benign intracranial hypertension as well as a procedural code for a CT or MRI and a code for lumbar puncture procedure within 15 days of the PTCS code. Controls were selected from the cohort using density-based sampling.Results: From a cohort of 9,053,240 subjects, there were 288 cases of PTCS corresponding to 2,880 controls. The adjusted RRs for two or more prescriptions of oral combined contraceptive was 0.62 (95% confidence interval 0.39-0.99). RRs for overall HC use was 0.91 (95% CI 0.39-2.12) for one prescription of HCs and 0.69 (95% CI 0.45-1.05) for two or more prescriptions. The RRs for one and two or more prescriptions of progestin only HCs were 0.75 (95% CI 0.08-7.46) and 1.06 (95% CI 0.42-2.69), respectively.Conclusions: Overall HC use does not have a significant effect on incidence of PTCS, however harm associated with progestin-only contraceptives cannot be excluded.

In this case report, the clinical presentation of an inflammatory orbitopathy seen following treatment with ipilimumab is described. After 3 rounds of ipilimumab (10 mg/kg) treatment for Stage III metastatic melanoma, the subject of this case report developed acute eye pain and proptosis. At initial presentation, she had marked proptosis and diffuse severe ophthalmoparesis. After treatment with high-dose steroids, over a period of 6 months, the symptoms gradually resolved fully. Although the condition may mimic thyroid-associated orbitopathy, imaging and laboratory features suggest that the orbitopathy associated with ipilimumab is not a secondary effect of thyroid dysfunction but a distinct inflammatory condition. The authors conclude that immune-related side effects can occur with biologic agents used to treat malignancies and these side-effects can involve the eye. This case illustrates the occurrence of an inflammatory orbitopathy associated with ipilimumab treatment.

The effect of anoxia on Na+/H+ exchange activity was examined in acutely isolated adult rat hippocampal CA1 neurons loaded with the H+-sensitive fluorophore, BCECF. Five-minute anoxia imposed under nominally HCO3–/CO2-free conditions induced a fall in pHi, the magnitude of which was smaller following prolonged exposure to medium in which N-methyl-d-glucamine (NMDG+) was employed as an extracellular Na+ (Na+o) substitute. Also consistent with the possibility that Na+/H+ exchange becomes inhibited soon after the induction of anoxia, rates of Na+o-dependent pHi recovery from internal acid loads imposed during anoxia were slowed, compared to rates of Na+o-dependent pHi recovery observed prior to anoxia. At the time at which rates of pHi recovery were reduced during anoxia, cellular adenosine triphosphate (ATP) levels had fallen to 35% of preanoxic levels, suggesting that ATP depletion might contribute to the observed inhibition of Na+/H+ exchange. In support, incubation of neurons with 2-deoxyglucose and antimycin A under normoxic conditions induced a fall in cellular ATP levels that was also associated with reduced Na+o-dependent rates of pHi recovery from imposed acid loads; conversely, pre-treatment with 10 mm creatine attenuated the effects of anoxia to reduce both ATP levels and Na+o-dependent rates of pHi recovery from internal acid loads. Taken together, the results are consistent with the possibility that functional Na+/H+ exchange activity in adult rat CA1 neurons declines soon after the onset of anoxia, possibly as a result of anoxia-induced falls in intracellular ATP.

NMDA-type glutamate receptors play a critical role in neuronal synaptogenesis, plasticity, and excitotoxic death. Recent studies indicate that functional NMDA receptors are also expressed in certain glial populations in the normal brain. Using immunohistochemical methods, we detected the presence of the NMDA receptor 2B (NR2B) subunit of the NMDA receptor in neurons but not astrocytes in the CA1 and subicular regions of the rat hippocampus. However, after ischemia-induced neuronal death in these regions, double immunohistochemical labeling revealed that NR2B subunits colocalized with the astrocyte marker glial fibrillary acid protein and with NR1 subunits that are required for functional NMDA receptors. NR2B expression was first observed 3 d after ischemia and reached a peak at 28 d. At 56 d, only a few NR2B-expressing astrocytes were still present. In vitro, when postnatal hippocampal cultures were subjected to 5 min of anoxia, it resulted in NR2B expression on astrocytes in the glial feed layer. Imaging of intracellular calcium with postanoxic cultures and astrocytes isolated acutely from the ischemic hippocampus revealed a rise in intracellular [Ca(2+)] after stimulation with the specific agonist NMDA. The response could be blocked reversibly with the competitive antagonist 2-amino-5-phosphonovalerate and attenuated by the NR2B-selective antagonist ifenprodil. Control astrocytes were not responsive to NMDA but responded to glutamate. An understanding of the role of astrocytes that express functional NMDA receptors in response to ischemia may guide development of novel stroke therapies.

Success rates for genomic analyses of highly heterogeneous disorders can be greatly improved if a large cohort of patient data is assembled to enhance collective capabilities for accurate sequence variant annotation, analysis, and interpretation. Indeed, molecular diagnostics requires the establishment of robust data resources to enable data sharing that informs accurate understanding of genes, variants, and phenotypes. The "Mitochondrial Disease Sequence Data Resource (MSeqDR) Consortium" is a grass-roots effort facilitated by the United Mitochondria] Disease Foundation to identify and prioritize specific genomic data analysis needs of the global mitochondrial disease clinical and research community. A central Web portal (https://mseqdr.org) facilitates the coherent compilation, organization, annotation, and analysis of sequence data from both nuclear and mitochondrial genomes of individuals and families with suspected mitochondria! disease. This Web portal provides users with a flexible and expandable suite of resources to enable variant-, gene-, and exome-level sequence analysis in a secure, Web-based, and user-friendly fashion. Users can also elect to share data with other MSeqDR Consortium members, or even the general public, either by custom annotation tracks or through the use of a convenient distributed annotation system (DAS) mechanism. A range of data visualization and analysis tools are provided to facilitate user interrogation and understanding of genomic, and ultimately phenotypic, data of relevance to mitochondrial biology and disease. Currently available tools for nuclear and mitochondrial gene analyses include an MSeqDR GBrowse instance that hosts optimized mitochondrial disease and mitochondrial DNA (mtDNA) specific annotation tracks, as well as an MSeqDR locus-specific database (LSDB) that curates variant data on more than 1300 genes that have been implicated in mitochondrial disease and/or encode mitochondria-localized proteins. MSeqDR is integrated with a diverse array of mtDNA data analysis tools that are both freestanding and incorporated into an online exome-level dataset curation and analysis resource (GEM.app) that is being optimized to support needs of the MSeqDR community. In addition, MSeqDR supports mitochondrial disease phenotyping and ontology tools, and provides variant pathogenicity assessment features that enable community review, feedback, and integration with the public ClinVar variant annotation resource. A centralized Web-based informed consent process is being developed, with implementation of a Global Unique Identifier (GUID) system to integrate data deposited on a given individual from different sources. Community-based data deposition into MSeqDR has already begun. Future efforts will enhance capabilities to incorporate phenotypic data that enhance genomic data analyses. MSeqDR will fill the existing void in bioinformatics tools and centralized knowledge that are necessary to enable efficient nuclear and mtDNA genomic data interpretation by a range of shareholders across both clinical diagnostic and research settings. Ultimately, MSeqDR is focused on empowering the global mitochondrial disease community to better define and explore mitochondrial diseases. (C) 2014 Elsevier Inc. All rights reserved.

Background: Fluoroquinolones (FQs) are one of the most prescribed classes of antibiotics in North America. There have been a number of cases reports linkingn FQs with secondary pseudotumor cerebri syndrome (PTCS) but data from large epidemiological studies are lacking. Methods: We conducted a case-control study of people 15-60 years of age from the LifeLink Database (IMS, USA). Cases had the first international classification for disease 9th edition clinical modification (ICD-9 CM) code for benign intracranial hypertension (BIH) as well as having received a procedure code for an MRI or CT scan and a lumbar puncture within 15 days or 30 days of receiving the BIH code. For each case, ten controls were selected and matched to the cases by age, gender and calendar time. Results: From a cohort of 6,110,723 people, there were 339 cases of PTCS and 3,390 corresponding controls. In the primary analysis, the adjusted rate ratio (RR) for current users for fluoroquinolones for both the 15 day and 30 day definitions were 5.67 (95% CI:2.72-11.83) and 4.15 (95% CI:2.29-7.50) respectively. Conclusions: Our study suggests an increase in the risk of PTCS with current users of fluoroquinolones. Patients who experience symptoms of raised intracranial pressure including headaches and double vision when on FQs should seek medical attention.

Pseudotumor cerebri syndrome (PTCS) is defined by the presence of elevated intracranial pressure (ICP) in the setting of normal brain parenchyma and cerebrospinal fluid (CSF). Headache, vision changes, and papilledema are common presenting features. Up to 10% of appropriately treated patients may experience permanent visual loss. The mechanism(s) underlying PTCS is unknown. PTCS occurs in association with a variety of conditions, including kidney disease, obesity, and adrenal insufficiency, suggesting endocrine and/or metabolic derangements may occur. Recent studies suggest that fluid and electrolyte balance in renal epithelia is regulated by a complex interaction of metabolic and hormonal factors; these cells share many of the same features as the choroid plexus cells in the central nervous system (CNS) responsible for regulation of CSF dynamics. Thus, we posit that similar factors may influence CSF dynamics in both types of fluid-sensitive tissues. Specifically, we hypothesize that, in patients with PTCS, mitochondrial metabolites (glutamate, succinate) and steroid hormones (cortisol, aldosterone) regulate CSF production and/or absorption. In this integrated mechanism review, we consider the clinical and molecular evidence for each metabolite and hormone in turn. We illustrate how related intracellular signaling cascades may converge in the choroid plexus, drawing on evidence from functionally similar tissues.

Purpose To examine the clinical, demographic, and anthropometric patient characteristics of secondary pseudotumor cerebri syndrome in children and adolescents based on the recently revised diagnostic criteria. Design Retrospective observational case series. Methods Patients seen at a tertiary children’s hospital for pseudotumor cerebri syndrome were classified as having either primary idiopathic (n = 59) or secondary pseudotumor cerebri syndrome (n = 16), as rigorously defined by recently revised diagnostic criteria. Outcomes included body mass index Z-scores (BMI-Z), height and weight Z-scores, demographics, and clinical features at presentation, such as headache, sixth nerve palsy, and cerebrospinal fluid (CSF) opening pressure. Results In this cohort, the associated conditions and exposures seen in definite secondary pseudotumor cerebri syndrome included tetracycline-class antibiotics (n = 11), chronic kidney disease (n = 3), withdrawal from chronic glucocorticoids (n = 1), and lithium (n = 1). Other associations observed in the possible secondary pseudotumor cerebri syndrome group included Down syndrome, vitamin A derivatives, and growth hormone. In comparison with primary pseudotumor cerebri syndrome, definite secondary pseudotumor cerebri syndrome patients were on average older (15.0 vs 11.6 years; P = .003, Mann-Whitney test). According to US Centers for Disease Control (CDC) classifications, 79% of children with secondary pseudotumor cerebri syndrome were either overweight or obese (36% overweight [n = 5] and 43% obese [n = 6]), as compared to 32% nationally. Conclusions Even when a potential inciting exposure is identified for pediatric pseudotumor cerebri syndrome, the possible contribution of overweight and obesity should be considered.

The ratiometric indicators 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein and Fura-2 were employed to examine, respectively, intracellular pH (pHi) and calcium ([Ca2+]i) changes evoked by anoxia in cultured postnatal rat hippocampal neurons at 37 degrees C. Under both HCO3-/CO2- and HEPES-buffered conditions, 3-, 5- or 10-min anoxia induced a triphasic change in pHi consisting of an initial fall in pHi, a subsequent rise in pHi in the continued absence of O2 and, finally, a further rise in pHi upon the return to normoxia, which recovered towards preanoxic steady-state pHi values if the duration of the anoxic insult was < or = 5 min. In parallel experiments performed on sister cultures, anoxia of 3, 5 or 10 min duration evoked rises in [Ca2+]i which, in all cases, commenced after the start of the fall in pHi, reached a peak at or just following the return to normoxia and then declined towards preanoxic resting levels. Removal of external Ca2+ markedly attenuated increases in [Ca2+]i, but failed to affect the pHi changes evoked by 5 min anoxia. The latency from the start of anoxia to the start of the increase in pHi observed during anoxia was increased by perfusion with media containing either 2 mM Na+, 20 mM glucose or 1 microM tetrodotoxin. Because each of these manoeuvres is known to delay the onset and/or attenuate the magnitude of anoxic depolarization, the results suggest that the rise in pHi observed during anoxia may be consequent upon membrane depolarization. This possibility was also suggested by the findings that Zn2+ and Cd2+, known blockers of voltage-dependent proton conductances, reduced the magnitude of the rise in pHi observed during anoxia. Under HCO3-/CO2-free conditions, reduction of external Na+ by substitution with N-methyl-D-glucamine (but not Li+) attenuated the magnitude of the postanoxic alkalinization, suggesting that increased Na+/H+ exchange activity contributes to the postanoxic rise in pHi. In support, rates of pHi recovery from internal acid loads imposed following anoxia were increased compared to control values established prior to anoxia in the same neurons. In contrast, rates of pHi recovery from acid loads imposed during anoxia were reduced, suggesting the possibility that Na+/H+ exchange is inhibited during anoxia. We conclude that the steady-state pHi response of cultured rat hippocampal neurons to transient anoxia is independent of changes in [Ca2+]i and is characterized by three phases which are determined, at least in part, by alterations in Na+/H- exchange activity and, possibly, by a proton conductance which is activated during membrane depolarization.

Whole-exome sequencing and autozygosity mapping studies, independently performed in subjects with defective combined mitochondrial OXPHOS-enzyme deficiencies, identified a total of nine disease-segregating FBXL4 mutations in seven unrelated mitochondrial disease families, composed of six singletons and three siblings. All subjects manifested early-onset lactic acidemia, hypotonia, and developmental delay caused by severe encephalomyopathy consistently associated with progressive cerebral atrophy and variable involvement of the white matter, deep gray nuclei, and brainstem structures. A wide range of other multisystem features were variably seen, including dysmorphism, skeletal abnormalities, poor growth, gastrointestinal dysmotility, renal tubular acidosis, seizures, and episodic metabolic failure. Mitochondrial respiratory chain deficiency was present in muscle or fibroblasts of all tested individuals, together with markedly reduced oxygen consumption rate and hyperfragmentation of the mitochondrial network in cultured cells. In muscle and fibroblasts from several subjects, substantially decreased mtDNA content was observed. FBXL4 is a member of the F-box family of proteins, some of which are involved in phosphorylation-dependent ubiquitination and/or G protein receptor coupling. We also demonstrate that FBXL4 is targeted to mitochondria and localizes in the intermembrane space, where it participates in an approximately 400 kDa protein complex. These data strongly support a role for FBXL4 in controlling bioenergetic homeostasis and mtDNA maintenance. FBXL4 mutations are a recurrent cause of mitochondrial encephalomyopathy onset in early infancy.

Mitochondrial disorders can cause an array of neuro-ophthalmologic manifestations such as ptosis, external ophthalmoparesis, nystagmus, pigmentary retinopathy, and optic neuropathy.1 The …

A case of giant cell arteritis was diagnosed in a woman who presented with bilateral loss of vision that did not improve with intravenous corticosteroid therapy. Preceding her vision loss, the patient had other symptoms consistent with this diagnosis, notably significant jaw pain and arthralgias. The diverse symptoms of giant cell arteritis are discussed, along with the features that can be used to distinguish jaw pain associated with this condition from the pain of temporomandibular joint pathology. An increased awareness of giant cell arteritis should lead to earlier diagnosis and treatment and avoidance of the devastating consequences of this condition.

A word-length effect is often described in pure alexia, with reading time proportional to the number of letters in a word. Given the frequent association of right hemianopia with pure alexia, it is uncertain whether and how much of the word-length effect may be attributable to the hemifield loss. To isolate the contribution of the visual field defect, we simulated hemianopia in healthy subjects with a gaze-contingent paradigm during an eye-tracking experiment. We found a minimal word-length effect of 14 ms/letter for full-field viewing, which increased to 38 ms/letter in right hemianopia and to 31 ms/letter in left hemianopia. We found a correlation between mean reading time and the slope of the word-length effect in hemianopic conditions. The 95% upper prediction limits for the word-length effect were 51 ms/letter in subjects with full visual fields and 161 ms/letter with simulated right hemianopia. These limits, which can be considered diagnostic criteria for an alexic word-length effect, were consistent with the reading performance of six patients with diagnoses based independently on perimetric and imaging data: two patients with probable hemianopic dyslexia, and four with alexia and lesions of the left fusiform gyrus, two with and two without hemianopia. Two of these patients also showed reduction of the word-length effect over months, one with and one without a reading rehabilitation program. Our findings clarify the magnitude of the word-length effect that originates from hemianopia alone, and show that the criteria for a word-length effect indicative of alexia differ according to the degree of associated hemifield loss.

Background:Current cognitive models propose that multiple processes are involved in reading and writing.Objective:Our goal was to use linguistic analyses to clarify the cognitive dysfunction behind two classic alexic syndromes.Methods:We report four experiments on two patients, one with alexia without agraphia following occipitotemporal lesions, and one with alexia with agraphia from a left angular gyral lesion.Results:The patient with occipital lesions had trouble discriminating real letters from foils and his reading varied with word-length but not with linguistic variables such as part of speech, word frequency or imageability. He read pseudo-words and words with regular spelling better, indicating preserved use of grapheme-to-phoneme pronunciation rules. His writing showed errors that reflected reliance on ‘phoneme-to-grapheme’ spelling rules. In contrast, the patient with a left angular gyral lesion showed better recognition of letters, words and their meanings. His reading was better for words with high imageability but displayed semantic errors and an inability to use ‘grapheme-to-phoneme’ rules, features consistent with deep dyslexia. His agraphia showed impaired access to both an internal lexicon and ‘phoneme-to-grapheme’ rules.Conclusion:Some cases of pure alexia may be a perceptual word-form agnosia, with loss of internal representations of letters and words, while the angular gyral syndrome of alexia with agraphia is a linguistic deep dyslexia. The presence or absence of agraphia does not always distinguish between the two; rather, writing can mirror the reading deficits, being more obvious and profound in the case of an angular gyral syndrome.

Mechanisms that contribute to Na+influx during and immediately after 5 min anoxia were investigated in cultured rat hippocampal neurons loaded with the Na+-sensitive fluorophore sodium-binding benzofuran isophthalate. During anoxia, an influx of Na+in the face of reduced Na+,K+-ATPase activity caused a rise in [Na+]i. After the return to normoxia, Na+,K+-ATPase activity mediated the recovery of [Na+]idespite continued Na+entry. Sodium influx during and after anoxia occurred through multiple pathways and increased the longer neurons were maintained in culture. Under the experimental conditions used, Na+entry during anoxia did not reflect the activation of ionotropic glutamate receptors, TTX- or lidocaine-sensitive Na+channels, plasmalemmal Na+/Ca2+exchange, Na+/H+exchange, or\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{HC}\mathrm{O}_{3}^{-}\) \end{document}-dependent mechanisms; rather, contributions were received from a Gd3+-sensitive pathway activated by reactive oxygen species and Na+/K+/2Cl-cotransport in neurons maintained for 6-10 and 11-14 din vitro(DIV), respectively. Sodium entry immediately after anoxia was not attributable to the activation of ionotropic glutamate receptors, voltage-activated Na+channels, or Na+/K+/2Cl-cotransport; rather, it occurred via Na+/Ca2+exchange, Na+/H+exchange, and a Gd3+-sensitive pathway similar to that observed during anoxia; 11-14 DIV neurons received an additional contribution from an\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{HC}\mathrm{O}_{3}^{-}\) \end{document}-dependent mechanism(s). The results provide insight into the intrinsic mechanisms that contribute to disturbed internal Na+homeostasis during and immediately after anoxia in rat hippocampal neurons and, in this way, may play a role in the pathogenesis of anoxic or ischemic cell injury.

We report a method for the concurrent measurement of intracellular [Na+] ([Na+ ]i) and pH (pHi) in cells co-loaded with SBFI, a Na+-sensitive fluorophore, and either carboxy SNARF-1 or SNARF-5F, H+-sensitive fluorophores. With the optical filters specified, fluorescence emissions from SBFI and either SNARF derivative were sufficiently distinct to allow the accurate measurement of [Na+]i and pHi in rat hippocampal neurons. Neither the Na+ sensitivity of SBFI nor the pH sensitivities of carboxy SNARF-1 or SNARF-5F was affected by the presence of a SNARF derivative or SBFI, respectively. In addition, the calibration parameters obtained in neurons single-loaded with SBFI, carboxy SNARF-1 or SNARF-5F were not significantly influenced by the presence of a second fluorophore. In contrast to the established weak sensitivity of SBFI for protons, both SNARF derivatives appeared essentially insensitive to changes in [Na+]i. The utility of the technique was demonstrated in neurons co-loaded with SBFI and SNARF-5F, which was found to have a lower p Ka in situ than carboxy SNARF-1. There were no significant differences in the changes in [Na+]i and pHi observed in response either to intracellular acid loads imposed by the NH4+ prepulse technique or to transient periods of anoxia in neurons single-loaded with SBFI or SNARF-5F or co-loaded with both probes. The findings support the feasibility of using SBFI in conjunction with either carboxy SNARF-1 or SNARF-5F to concurrently and accurately measure [Na+]i and pHi.

The motuporamines are macrocyclic alkaloids that inhibit tumor cell invasion by an, as yet, unknown mechanism. A structure–activity study recently identified dihydromotuporamine C (dhMotC) as a highly active and readily synthesized analogue. Here, we show that dhMotC causes subtle cytoskeletal alterations in highly invasive MDA231 breast tumor cells that include an increase in the thickness and number of cytoplasmic actin stress fibers. Experiments with serum-starved Swiss 3T3 fibroblasts showed that micromolar concentrations of dhMotC that inhibit tumor cell invasion induce the formation of new stress fibers and large focal adhesion complexes that are dispersed around the entire cell periphery. dhMotC treatment of Swiss 3T3 cells also initiates a strong, long-lived activation of the small GTP-binding protein Rho, and it stimulates Rho kinase-dependent sodium–proton exchanger activity. Liposome-mediated cell loading of C3 exoenzyme prevents dhMotC-mediated Rho activation and stress fiber formation in 3T3 cells. C3 exoenzyme loading also reestablishes elongated MDA231 breast tumor cell invasion in the presence of dhMotC. Taken together, these results indicate that the ability to activate Rho is one important determinant of the anti-invasive activity of dhMotC.

The contributions of HCO(3)(-)-dependent, DIDS-sensitive mechanisms to the maintenance of steady-state pH(i), and the regulation of their activities by cAMP-dependent protein kinase (PKA), were investigated in CA1 neurons with the H(+)-sensitive fluorophore, BCECF. The addition of HCO(3)(-)/CO(2) to neurons with "low" (pH(i)or = 7.20) and "high" (pH(i)7.20) initial pH(i) values under Hepes-buffered conditions, increased and decreased steady-state pH(i), respectively. Conversely, under HCO(3)(-)/CO(2)-buffered conditions, DIDS caused pH(i) to decrease and increase in neurons with low and high initial pH(i) values, respectively. In the presence, but not the absence, of HCO(3)(-), the PKA inhibitor Rp-adenosine-3',5'-cyclic monophosphorothioate (Rp-cAMPS; 50 microM) evoked DIDS-sensitive increases and decreases in pH(i) in neurons with low and high initial pH(i) values, respectively. In contrast, in neurons with low initial pH(i) values, activation of PKA with the Sp isomer of cAMPS (Sp-cAMPS; 25 microM) elicited increases in pH(i) that were smaller in the presence than in the absence of HCO(3)(-), whereas in neurons with high initial pH(i) values, Sp-cAMPS-evoked rises in pH(i) were larger in the presence than in the absence of HCO(3)(-); the differences between the effects of Sp-cAMPS on pH(i) under the different buffering conditions were attenuated by DIDS. Consistent with the possibility that changes in the activities of HCO(3)(-)-dependent, DIDS-sensitive mechanisms contribute to the steady-state pH(i) changes evoked by the PKA modulators, in neurons with initial pH(i) valuesor = 7.20, Rp-cAMPS concurrently inhibited Na(+)-independent Cl(-)-HCO(3)(-) exchange and stimulated Na(+)-dependent Cl(-)-HCO(3)(-) exchange; in contrast, Sp-cAMPS concurrently stimulated Na(+)-independent Cl(-)-HCO(3)(-) exchange and inhibited Na(+)-dependent Cl(-)-HCO(3)(-) exchange. Data from a limited number of neurons with initial pH(i) values7.20 suggested that the directions of the reciprocal changes in anion exchange activities (inhibition or stimulation) evoked by Rp- and Sp-cAMPS may be opposite in cells with low vs. high resting pH(i) values. Taken together, the results indicate that the effects of modulating PKA activity on steady-state pH(i) in rat CA1 neurons under HCO(3)(-)/CO(2)-buffered conditions reflect not only changes in Na(+)-H(+) exchange activity but also changes in Na(+)-dependent and Na(+)-independent Cl(-)-HCO(3)(-) exchange activity that, in turn, may be dependent upon the initial pH(i).

The effects of anoxia on intracellular pH (pHi) were examined in acutely isolated adult rat hippocampal CA1 neurons loaded with the H+-sensitive fluorophore, 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein. During perfusion with HCO[Formula: see text]/CO2- or HEPES-buffered media (pH 7.35) at 37°C, 5- or 10-min anoxic insults were typified by an intracellular acidification on the induction of anoxia, a subsequent rise in pHiin the continued absence of O2, and a further internal alkalinization on the return to normoxia. The steady-state pHichanges were not consequent on changes in [Ca2+]iand, examined in the presence of HCO[Formula: see text], were not significantly affected by (DIDS). In the absence of HCO[Formula: see text], the magnitude of the postanoxic alkalinization was attenuated when external Na+was reduced by substitution with N-methyl-d-glucamine (NMDG+), but not Li+, suggesting that increased Na+/H+exchange activity contributes to this phase of the pHiresponse. In contrast, 100–500 μM Zn2+, a known blocker of H+-conductive pathways, reduced the magnitudes of the internal alkalinizations that occurred both during and following anoxia. The effects of NMDG+-substituted medium and Zn2+to reduce the increase in pHithat occurred after anoxia were additive. Consistent with the steady-state pHichanges, rates of pHirecovery from internal acid loads imposed immediately after anoxia were increased, and the application of Zn2+and/or perfusion with NMDG+-substituted medium slowed pHirecovery. Reducing extracellular pH from 7.35 to 6.60, or reducing ambient temperature from 37°C to room temperature, also attenuated the increases in steady-state pHiobserved during and after anoxia and reduced rates of pHirecovery from acid loads imposed in the immediate postanoxic period. Finally, inhibition of the cAMP/protein kinase A second-messenger system reduced the magnitude of the rise in pHiafter anoxia in a manner that was dependent on external Na+; conversely, activation of the system with isoproterenol increased the postanoxic alkalinization, an effect that was attenuated by pretreatment with propranolol, Rp-cAMPS, or when NMDG+(but not Li+) was employed as an external Na+substitute. The results suggest that a Zn2+-sensitive acid efflux mechanism, possibly a H+-conductive pathway activated by membrane depolarization, contributes to the internal alkalinization observed during anoxia in adult rat CA1 neurons. The rise in pHiafter anoxia reflects acid extrusion via the H+-conductive pathway and also Na+/H+exchange, activation of the latter being mediated, at least in part, through a cAMP-dependent signaling pathway.