Advances in the Rehabilitation of Hemispatial Inattention.

PURPOSE OF REVIEW: There continue to be a plethora of approaches to the rehabilitation of hemispatial inattention, from different forms of sensory stimulation (visual, auditory and somatosensory feedback), through all major modes of non-invasive brain stimulation to drug therapies. Here we summarise trials published in the years 2017-2022 and tabulate their effect sizes, with the aim of drawing on common themes that may serve to inform future rehabilitative studies. RECENT FINDINGS: Immersive virtual reality approaches to visual stimulation seem well tolerated, although they have yet to yield any clinically relevant improvements. Dynamic auditory stimulation looks very promising and has high potential for implementation. Robotic interventions are limited by their cost and are perhaps best suited to patients with a co-occurring hemiparesis. Regarding brain stimulation, rTMS continues to demonstrate moderate effects but tDCS studies have yielded disappointing results so far. Drugs, primarily aimed at the dopaminergic system, often demonstrate beneficial effects of a medium size, but as with many of the approaches, it seems difficult to predict responders and non-responders. Our main recommendation is that researchers consider incorporating single-case experimental designs into their studies as rehabilitation trials are likely to remain small in terms of patient numbers, and this is the best way to deal with all the factors that cause large between-subject heterogeneity.

α-Synuclein modulates fibronectin expression in the trabecular meshwork independent of TGFß2.

α-Synuclein (α-Syn) is implicated in Parkinson's disease (PD), a neuromotor disorder with prominent visual symptoms. The underlying cause of motor dysfunction has been studied extensively, and is attributed to the death of dopaminergic neurons mediated in part by intracellular aggregation of α-Syn. The cause of visual symptoms, however, is less clear. Neuroretinal degeneration due to the presence of aggregated α-Syn has been reported, but the evidence is controversial. Other symptoms including those arising from primary open angle glaucoma (POAG) are believed to be the side-effects of medications prescribed for PD. Here, we explored the alternative hypothesis that dysfunction of α-Syn in the anterior eye alters the interaction between the actin cytoskeleton of trabecular meshwork (TM) cells with the extracellular matrix (ECM), impairing their ability to respond to physiological changes in intraocular pressure (IOP). A similar dysfunction in neurons is responsible for impaired neuritogenesis, a characteristic feature of PD. Using cadaveric human and bovine TM tissue and primary human TM cells as models, we report two main observations: 1) α-Syn is expressed in human and bovine TM cells, and significant amounts of monomeric and oligomeric α-Syn are present in the AH, and 2) primary human TM cells and human and bovine TM tissue endocytose extracellular recombinant monomeric and oligomeric α-Syn via the prion protein (PrPC), and upregulate fibronectin (FN) and α-smooth muscle actin (α-SMA), fibrogenic proteins implicated in POAG. Transforming growth factor ß2 (TGFß2), a fibrogenic cytokine implicated in ∼50% cases of POAG, is also increased, and so is RhoA-associated coiled-coil-containing protein kinase 1 (ROCK-1). However, silencing of α-Syn in primary human TM cells reduces FN, α-SMA, and ROCK-1 in the absence or presence of over-expressed active TGFß2, suggesting modulation of FN and ROCK-1 independent of, or upstream of TGFß2. These observations suggest that extracellular α-Syn modulates ECM proteins in the TM independently or via PrPC by activating the RhoA-ROCK pathway. These observations reveal a novel function of α-Syn in the anterior eye, and offer new therapeutic options.

Neurofilament light chain: a new marker for neuronal decay in the anterior chamber fluid of patients with glaucoma.

BACKGROUND/AIMS: Neurofilament light chain (NfL) levels in cerebrospinal fluid and serum are reliable indicators for neuroaxonal damage in a broad spectrum of neurodegenerative diseases. Herein, we investigate NfL levels in serum and anterior chamber fluid of patients with glaucoma. METHODS: Patients scheduled for routine glaucoma or cataract surgery were recruited for this study. Retinal nerve fibre layer thickness was measured by optical coherence tomography (OCT, Heidelberg Spectralis). NfL levels in serum and in anterior chamber fluid were analysed with Simoa SR-X Analyzer (Quanterix; NFLIGHT, Lexington, Massachusetts, USA). T-test was used for parametric data and Mann-Whitney-U test for nonparametric data. Spearman's rank-order correlation was used to investigate correlations. P values<0.05 were considered as statistically significant. RESULTS: Sixty patients with glaucoma and 58 controls were enrolled. Serum NfL concentration of patients with glaucoma was similar to serum NfL concentration in controls (median (IQR); 22.7 (18.9) pg/mL vs 22.5 (24.0) pg/mL; p=0.763). A positive correlation of serum NfL with age was observed in both patients with glaucoma (r=0.77; p<0.001) and in the control group (r=0.82, p<0.001). In the anterior chamber fluid, the NfL concentration was substantially increased in patients with glaucoma compared with controls (20.7 (101.3) pg/mL vs 3.1 (2.9) pg/mL; p<0.001). Furthermore, we found a positive correlation of anterior chamber fluid NfL with preoperative intraocular pressure (r=0.39, p=0.003) and with retinal nerve fibre layer thickness (r=0.58, p<0.001). CONCLUSION: NfL levels in anterior chamber fluid are elevated in patients with glaucoma and correlate with intraocular pressure and retinal nerve fibre layer thickness. The presented data strongly support anterior chamber fluid NfL as a new marker for glaucoma.

ß-Cleavage of the prion protein in the human eye: Implications for the spread of infectious prions and human ocular disorders.

Recently, we reported ß-cleavage of the prion protein (PrPC) in human ocular tissues. Here, we explored whether this is unique to the human eye, and its functional implications. A comparison of the cleavage pattern of PrPC in human ocular tissues with common nocturnal and diurnal animals revealed mainly ß-cleavage in humans, and mostly full-length PrPC in animal retinas. Soluble FL PrPC and N-terminal fragment (N2) released from ß-cleavage was observed in the aqueous and vitreous humor (AH & VH). Expression of human PrPC in ARPE-19 cells, a human retinal pigmented epithelial cell line, also showed ß-cleaved PrPC. Surprisingly, ß-cleavage was not altered by a variety of insults, including oxidative stress, suggesting a unique role of this cleavage in the human eye. It is likely that ß-cleaved C- or N-terminal fragments of PrPC protect from various insults unique to the human eye. On the contrary, ß-cleaved C-terminus of PrPC is susceptible to conversion to the pathological PrP-scrapie form, and includes the binding sites for ß1-integrin and amyloid-ß, molecules implicated in several ocular disorders. Considering the species and tissue-specific cleavage of PrPC, our data suggest re-evaluation of prion infectivity and other ocular disorders of the human eye conducted in mouse models.

Delay in Seeking Medical Treatment Among Patients With Acute Coronary Syndrome.

Background Various Indian registries have documented a delay of more than five hours for acute coronary syndrome patients from onset of symptoms to reaching thrombolysis-enabled centres. We conducted this study to evaluate the factors responsible for pre-hospital delay in acute coronary syndrome patients. Methods This was a descriptive cross-sectional study conducted in consecutive acute coronary syndrome patients who reported to the tertiary care medical centre in North India. A standardized tool was used to record the demographic data, socioeconomic status and clinical presentation of patients. All factors which led to pre-hospital delay were noted and the appropriate statistical tests were used for analysis. Results A total of 130 patients (males=93, females=37) were included in the study. The median time at which the acute coronary syndrome patients presented to the thrombolysis and percutaneous coronary intervention enabled centre was 490 minutes (range: 20 - 810 minutes) and 710 minutes (range: 45 - 940 minutes) respectively. The various factors responsible for prehospital delay were rural residence (p-value <0.0001), visit to local dispensary (p-value=0.0023), delay in getting transport (p-value=0.03) and misinterpretation of cardiac symptoms (p-value=0.0004). A significant but weak negative correlation was found between per capita income, decision making time and time taken to receive thrombolytic therapy. Out of a total of 83 ST-elevation myocardial infarction patients, only 46 (51.80%) were thrombolysed. Though 69/83 (83.13%) ST-elevation myocardial infarction patients reached thrombolysis enabled centre directly, only nine (10.84%) were thrombolysed at first medical contact; the rest were transferred to the percutaneous coronary intervention-enabled centre without any prior information.  Conclusion Our study concludes that besides socioeconomic and demographic variables, lack of public awareness, well established public transport & health insurance system lead to significant pre-hospital delays and increase the time to revascularization. Besides, judgemental error on the part of medical practitioners in the peripheries also significantly delays thrombolysis in ST-elevation myocardial infarction patients.

Release of Iron-Loaded Ferritin in Sodium Iodate-Induced Model of Age Related Macular Degeneration: An In-Vitro and In-Vivo Study.

To evaluate the role of iron in sodium iodate (NaIO3)-induced model of age-related macular degeneration (AMD) in ARPE-19 cells in-vitro and in mouse models in-vivo. ARPE-19 cells, a human retinal pigment epithelial cell line, was exposed to 10 mM NaIO3 for 24 h, and the expression and localization of major iron modulating proteins was evaluated by Western blotting (WB) and immunostaining. Synthesis and maturation of cathepsin-D (cat-D), a lysosomal enzyme, was evaluated by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) and WB, respectively. For in-vivo studies, C57BL/6 mice were injected with 40 mg/kg mouse body weight of NaIO3 intraperitoneally, and their retina was evaluated after 3 weeks as above. NaIO3 induced a 10-fold increase in ferritin in ARPE-19 cells, which co-localized with LC3II, an autophagosomal marker, and LAMP-1, a lysosomal marker. A similar increase in ferritin was noted in retinal lysates and retinal sections of NaIO3-injected mice by WB and immunostaining. Impaired synthesis and maturation of cat-D was also noted. Accumulated ferritin was loaded with iron, and released from retinal pigmented epithelial (RPE) cells in Perls' and LAMP-1 positive vesicles. NaIO3 impairs lysosomal degradation of ferritin by decreasing the transcription and maturation of cat-D in RPE cells. Iron-loaded ferritin accumulates in lysosomes and is released in lysosomal membrane-enclosed vesicles to the extracellular milieu. Accumulation of ferritin in RPE cells and fusion of ferritin-containing vesicles with adjacent photoreceptor cells is likely to create an iron overload, compromising their viability. Moreover, reduced activity of cat-D is likely to promote accumulation of other cellular debris in lysosomal vesicles, contributing to AMD-like pathology.

Upregulation of brain hepcidin in prion diseases.

Accumulation of redox-active iron in human sporadic Creutzfeldt-Jakob disease (sCJD) brain tissue and scrapie-infected mouse brains has been demonstrated previously. Here, we explored whether upregulation of local hepcidin secreted within the brain is the underlying cause of iron accumulation and associated toxicity. Using scrapie-infected mouse brains, we demonstrate transcriptional upregulation of hepcidin relative to controls. As a result, ferroportin (Fpn), the downstream effector of hepcidin and the only known iron export protein was downregulated, and ferritin, an iron storage protein was upregulated, suggesting increased intracellular iron. A similar transcriptional and translational upregulation of hepcidin, and decreased expression of Fpn and an increase in ferritin expression was observed in sCJD brain tissue. Further evaluation in human neuroblastoma cells (M17) exposed to synthetic mini-hepcidin showed downregulation of Fpn, upregulation of ferritin, and an increase in reactive oxygen species (ROS), resulting in cytotoxicity in a dose-dependent manner. Similar effects were noted in primary neurons isolated from mouse brain. As in M17 cells, primary neurons accumulated ferritin and ROS, and showed toxicity at five times lower concentration of mini-hepcidin. These observations suggest that upregulation of brain hepcidin plays a significant role in iron accumulation and associated neurotoxicity in human and animal prion disorders.

Upregulation of Local Hepcidin Contributes to Iron Accumulation in Alzheimer's Disease Brains.

BACKGROUND: Accumulation of iron is a consistent feature of Alzheimer's disease (AD) brains. The underlying cause, however, remains debatable. OBJECTIVE: To explore whether local hepcidin synthesized by brain cells contributes to iron accumulation in AD brains. METHODS: Brain tissue from the cingulate cortex of 33 cases of AD pre-assigned to Braak stage I-VI, 6 cases of non-dementia, and 15 cases of non-AD dementia were analyzed for transcriptional upregulation of hepcidin by RT-qPCR and RT-PCR. Change in the expression of ferritin, ferroportin (Fpn), microglial activation marker Iba1, IL-6, and TGFß2 was determined by western blotting. Total tissue iron was determined by colorimetry. RESULTS: Significant transcriptional upregulation of hepcidin was observed in Braak stage III-VI relative to Braak stage I and II, non-AD dementia, and non-dementia samples. Ferritin was increased in Braak stage V, and a significant increase in tissue iron was evident in Braak stage III-VI. The expression of Iba1 and IL-6 was also increased in Braak stage III-VI relative to Braak stage I and II and non-AD dementia samples. Amyloid-ß plaques were absent in most Braak stage I and II samples, and present in Braak stage III-VI samples with few exceptions. CONCLUSION: These observations suggest that upregulation of brain hepcidin is mediated by IL-6, a known transcriptional activator of hepcidin. The consequent downregulation of Fpn on neuronal and other cells results in accumulation of iron in AD brains. The increase in hepcidin is disease-specific, and increases with disease progression, implicating AD-specific pathology in the accumulation of iron.

Streamlined alpha-synuclein RT-QuIC assay for various biospecimens in Parkinson's disease and dementia with Lewy bodies.

Definitive diagnosis of Parkinson's disease (PD) and dementia with Lewy bodies (DLB) relies on postmortem finding of disease-associated alpha-synuclein (αSynD) as misfolded protein aggregates in the central nervous system (CNS). The recent development of the real-time quaking induced conversion (RT-QuIC) assay for ultrasensitive detection of αSynD aggregates has revitalized the diagnostic values of clinically accessible biospecimens, including cerebrospinal fluid (CSF) and peripheral tissues. However, the current αSyn RT-QuIC assay platforms vary widely and are thus challenging to implement and standardize the measurements of αSynD across a wide range of biospecimens and in different laboratories. We have streamlined αSyn RT-QuIC assay based on a second generation assay platform that was assembled entirely with commercial reagents. The streamlined RT-QuIC method consisted of a simplified protocol requiring minimal hands-on time, and allowing for a uniform analysis of αSynD in different types of biospecimens from PD and DLB. Ultrasensitive and specific RT-QuIC detection of αSynD aggregates was achieved in million-fold diluted brain homogenates and in nanoliters of CSF from PD and DLB cases but not from controls. Comparative analysis revealed higher seeding activity of αSynD in DLB than PD in both brain homogenates and CSF. Our assay was further validated with CSF samples of 214 neuropathologically confirmed cases from tissue repositories (88 PD, 58 DLB, and 68 controls), yielding a sensitivity of 98% and a specificity of 100%. Finally, a single RT-QuIC assay protocol was employed uniformly to detect seeding activity of αSynD in PD samples across different types of tissues including the brain, skin, salivary gland, and colon. We anticipate that our streamlined protocol will enable interested laboratories to easily and rapidly implement the αSyn RT-QuIC assay for various clinical specimens from PD and DLB. The utilization of commercial products for all assay components will improve the robustness and standardization of the RT-QuIC assay for diagnostic applications across different sites. Due to ultralow sample consumption, the ultrasensitive RT-QuIC assay will facilitate efficient use and sharing of scarce resources of biospecimens. Our streamlined RT-QuIC assay is suitable to track the distribution of αSynD in CNS and peripheral tissues of affected patients. The ongoing evaluation of RT-QuIC assay of αSynD as a potential biomarker for PD and DLB in clinically accessible biospecimens has broad implications for understanding disease pathogenesis, improving early and differential diagnosis, and monitoring therapeutic efficacies in clinical trials.

Retinal Degeneration and Alzheimer's Disease: An Evolving Link.

Age-related macular degeneration (AMD) and glaucoma are degenerative conditions of the retina and a significant cause of irreversible blindness in developed countries. Alzheimer's disease (AD), the most common dementia of the elderly, is often associated with AMD and glaucoma. The cardinal features of AD include extracellular accumulation of amyloid ß (Aß) and intracellular deposits of hyper-phosphorylated tau (p-tau). Neuroinflammation and brain iron dyshomeostasis accompany Aß and p-tau deposits and, together, lead to progressive neuronal death and dementia. The accumulation of Aß and iron in drusen, the hallmark of AMD, and Aß and p-tau in retinal ganglion cells (RGC), the main retinal cell type implicated in glaucoma, and accompanying inflammation suggest overlapping pathology. Visual abnormalities are prominent in AD and are believed to develop before cognitive decline. Some are caused by degeneration of the visual cortex, while others are due to RGC loss or AMD-associated retinal degeneration. Here, we review recent information on Aß, p-tau, chronic inflammation, and iron dyshomeostasis as common pathogenic mechanisms linking the three degenerative conditions, and iron chelation as a common therapeutic option for these disorders. Additionally discussed is the role of prion protein, infamous for prion disorders, in Aß-mediated toxicity and, paradoxically, in neuroprotection.

Prions and prion diseases: Insights from the eye.

Prion diseases are invariably fatal neurodegenerative disorders that have gained much publicity due to their transmissible nature. Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common human prion disorder, with an incidence of 1 in a million. Inherited prion disorders are relatively rare, and associated with mutations in the prion protein gene. More than 50 different point mutations, deletions, and insertions have been identified so far. Most are autosomal dominant and fully penetrant. Prion disorders also occur in animals, and are of major concern because of the potential for spreading to humans. The principal pathogenic event underlying all prion disorders is a change in the conformation of prion protein (PrPC) from a mainly α-helical to a ß-sheet rich isoform, PrP-scrapie (PrPSc). Accumulation of PrPSc in the brain parenchyma is the major cause of neuronal degeneration. The mechanism by which PrPSc is transmitted, propagates, and causes neurodegenerative changes has been investigated over the years, and several clues have emerged. Efforts are also ongoing for identifying specific and sensitive diagnostic tests for sCJD and animal prion disorders, but success has been limited. The eye is suitable for these evaluations because it shares several anatomical and physiological features with the brain, and can be observed in vivo during disease progression. The retina, considered an extension of the central nervous system, is involved extensively in prion disorders. Accordingly, Optical Coherence Tomography and electroretinogram have shown some promise as pre-mortem diagnostic tests for human and animal prion disorders. However, a complete understanding of the physiology of PrPC and pathobiology of PrPSc in the eye is essential for developing specific and sensitive tests. Below, we summarize recent progress in ocular physiology and pathology in prion disorders, and the eye as an anatomically accessible site to diagnose, monitor disease progression, and test therapeutic options.

Protecting people with multiple sclerosis through vaccination.

Vaccination is one of the most effective and cost-efficient methods for protecting people with multiple sclerosis (MS) from infections. However, use of vaccines has often been problematic because of misguided concerns that they may exacerbate the disease and/or that some disease-modifying therapies may influence the immune response to immunisations and/or their safety. People with MS risk higher morbidity and mortality from vaccine-preventable infections. It is, therefore, important to address any patient's reluctance to accept vaccination and to provide clear guidance for clinicians on which vaccinations to consider proactively. We have reviewed the current literature and provide recommendations regarding vaccines in adults with MS, including specific advice regarding vaccination safety in patients receiving-or going to receive-disease-modifying therapies, vaccination during pregnancy, pretravel counselling and patient education.

TGFß2-Hepcidin Feed-Forward Loop in the Trabecular Meshwork Implicates Iron in Glaucomatous Pathology.

Purpose: Elevated levels of transforming-growth-factor (TGF)-ß2 in the trabecular meshwork (TM) and aqueous humor are associated with primary open-angle glaucoma (POAG). The underlying mechanism includes alteration of extracellular matrix homeostasis through Smad-dependent and independent signaling. Smad4, an essential co-Smad, upregulates hepcidin, the master regulator of iron homeostasis. Here, we explored whether TGF-ß2 upregulates hepcidin, implicating iron in the pathogenesis of POAG. Methods: Primary human TM cells and human and bovine ex vivo anterior segment organ cultures were exposed to bioactive TGF-ß2, hepcidin, heparin (a hepcidin antagonist), or N-acetyl carnosine (an antioxidant), and the change in the expression of hepcidin, ferroportin, ferritin, and TGF-ß2 was evaluated by semiquantitative RT-PCR, Western blotting, and immunohistochemistry. Increase in reactive oxygen species (ROS) was quantified with dihydroethidium, an ROS-sensitive dye. Results: Primary human TM cells and bovine TM tissue synthesize hepcidin locally, which is upregulated by bioactive TGF-ß2. Hepcidin downregulates ferroportin, its downstream target, increasing ferritin and iron-catalyzed ROS. This causes reciprocal upregulation of TGF-ß2 at the transcriptional and translational levels. Heparin downregulates hepcidin, and reduces TGF-ß2-mediated increase in ferritin and ROS. Notably, both heparin and N-acetyl carnosine reduce TGF-ß2-mediated reciprocal upregulation of TGF-ß2. Conclusions: The above observations suggest that TGF-ß2 and hepcidin form a self-sustained feed-forward loop through iron-catalyzed ROS. This loop is partially disrupted by a hepcidin antagonist and an anti-oxidant, implicating iron and ROS in TGF-ß2-mediated POAG. We propose that modification of currently available hepcidin antagonists for ocular use may prove beneficial for the therapeutic management of TGF-ß2-associated POAG.

Local synthesis of hepcidin in the anterior segment of the eye: A novel observation with physiological and pathological implications.

PURPOSE: The avascular cornea, trabecular meshwork (TM), and lens obtain iron, an essential biometal, from the aqueous humor (AH). The mechanism by which this exchange is regulated, however, is unclear. Recently we reported that non-pigmented ciliary epithelial cells express ferroportin (Fpn) (Ashok, 2018b), an iron export protein modulated by hepcidin, the master regulator of iron homeostasis secreted mainly by the liver. Here, we explored whether ciliary epithelial and other cells in the anterior segment synthesize hepcidin, suggesting local regulation of iron exchange at this site. METHODS: Human and bovine eyes were dissected to isolate the ciliary body (CB), corneal endothelial (CE), TM, lens epithelial (LE), and outer epithelial cell layer of the iris. Total mRNA and protein lysates were processed to evaluate the synthesis and expression of hepcidin, the iron regulatory peptide hormone, Fpn, the only known iron export protein, ceruloplasmin (Cp), a ferroxidase necessary for iron export, transferrin receptor (TfR), a major iron uptake protein, and ferritin, a major iron storage protein. A combination of techniques including reverse transcription polymerase chain reaction (RT-PCR) of total mRNA, Western blotting of protein lysates, and immunofluorescence of fixed tissue sections were used to accomplish these goals. RESULTS: RT-PCR of isolated tissue samples revealed hepcidin-specific mRNA in the CB, TM, CE, and LE of the bovine eye. Western blotting of protein lysates from these tissues showed reactivity for hepcidin, Fpn, ferritin, and TfR. Western blotting and immunohistochemistry of similar tissues isolated from cadaveric human eyes showed expression of hepcidin, Fpn, and Cp in these samples. Notably, Fpn and Cp were expressed on the basolateral membrane of non-pigmented ciliary epithelial cells, facing the AH. CONCLUSIONS: Synthesis and expression of hepcidin and Fpn in the ciliary epithelium suggests local regulation of iron transport from choroidal plexus in the ciliary body to the AH across the blood-aqueous barrier. Expression of hepcidin and Fpn in CE, TM, and LE cells indicates additional regulation of iron exchange between the AH and cornea, TM, and lens, suggesting autonomous regulation of iron homeostasis in the anterior segment. Physiological and pathological implications of these observations are discussed.

Prion protein modulates endothelial to mesenchyme-like transition in trabecular meshwork cells: Implications for primary open angle glaucoma.

Endothelial-to-mesenchyme-like transition (Endo-MT) of trabecular meshwork (TM) cells is known to be associated with primary open angle glaucoma (POAG). Here, we investigated whether the prion protein (PrPC), a neuronal protein known to modulate epithelial-to-mesenchymal transition in a variety of cell types, is expressed in the TM, and plays a similar role at this site. Using a combination of primary human TM cells and human, bovine, and PrP-knock-out (PrP-/-) mouse models, we demonstrate that PrPC is expressed in the TM of all three species, including endothelial cells lining the Schlemm's canal. Silencing of PrPC in primary human TM cells induces aggregation of ß1-integrin and upregulation of α-smooth muscle actin, fibronectin, collagen 1A, vimentin, and laminin, suggestive of transition to a mesenchyme-like phenotype. Remarkably, intraocular pressure is significantly elevated in PrP-/- mice relative to wild-type controls, suggesting reduced pliability of the extracellular matrix and increased resistance to aqueous outflow in the absence of PrPC. Since PrPC is cleaved by members of the disintegrin and matrix-metalloprotease family that are increased in the aqueous humor of POAG arising from a variety of conditions, it is likely that concomitant cleavage of PrPC exaggerates and confounds the pathology by inducing Endo-MT-like changes in the TM.

Comparison between invasive and noninvasive blood pressure measurements in critically ill patients receiving inotropes.

OBJECTIVE: The aim of this study was to compare invasive and noninvasive monitoring of blood pressure (BP) in patients on inotropes. SETTINGS AND DESIGN: This study was carried out in the ICU of a tertiary care centre. The design was comparative analytical. PATIENTS AND METHODS: Thirty-six adult patients receiving inotropes with invasive arterial BP monitoring were studied. Systolic and diastolic BPs were recorded simultaneously using invasive (radial arterial cannula) and noninvasive (Philips Intellivue MP-60 oscillometric monitor attached to the opposite arm) methods every 30 min. STATISTICAL ANALYSIS: Agreement (precision) between both the methods was assessed using Bland-Altman analysis. A difference of more than 10 mmHg was considered clinically unacceptable. Linear regression of difference with invasive BP and analysis of variance with Tukey's correction of difference with the number of inotropes were carried out. RESULTS: Overall, 1400 pairs of systolic and diastolic BP measurements were obtained. Systolic and diastolic pressures showed a difference of 2.3±16.9 and 0.7±10.6 mmHg, respectively. In all, 93.4% of systolic and 98.6% of diastolic pressure measurements were within the limits of agreement. The difference was clinically acceptable in 54.2% of measurements of systolic and 74.1% of diastolic measurements. Both systolic and diastolic BP differences were correlated with the number of inotropes that the patient was receiving. CONCLUSION: Noninvasive BP measurement using an oscilllometric monitor (Philips Intellivue MP-60) is not a reliable alternative to invasive intra-arterial measurement in patients receiving inotropes. The observed difference increased with the number of inotropes that the patient was receiving.

Quality of Life Among Children Who Had Undergone Ventriculoperitoneal Shunt Surgery.

BACKGROUND: Ventriculoperitoneal (VP) shunting is the most common neurosurgical treatment for hydrocephalus. In spite of significant developments in the technology and design of shunt systems, shunt surgery is still associated with morbidity. AIM: To identify the problems faced by children on VP shunt and assess their quality of life (QOL). SETTING AND DESIGN: A cross-sectional exploratory study. MATERIALS AND METHODS: A total of 31 children on VP shunt were selected through consecutive sampling technique, and hydrocephalus outcome questionnaire was used to collect the data, with the converted metric score ranging from 0 to 1. Hydrocephalus due to stroke, hemorrhage, and malignant tumors was excluded. RESULTS: The mean age of patients was 11.51 ± 4.26 years. Headache and generalized pain were the common problems experienced (42%). The mean score of QOL was 0.67 ± 0.21. Among the three domains, cognitive domain was the most affected. Among the clinicoradiological factors, multiple surgeries (P = 0.02) had the most significant impact on QOL. CONCLUSION: Children who underwent VP shunt face various health-related problems in different domains and low QOL. Although cognitive domain was the most affected, multiple surgeries had the most significant impact on QOL. Appropriately focused interventions and holistic management are essential to improve the QOL of children undergoing VP shunt.

Prion protein modulates iron transport in the anterior segment: Implications for ocular iron homeostasis and prion transmission.

Iron is an essential biometal in the aqueous humor, the principal source of nutrients for the avascular cornea and the lens. Here, we explored whether the ciliary body (CB), the source of aqueous humor, transports iron, and if the prion protein (PrPC) facilitates this process as in the outer retina. Using a combination of human, bovine, and mouse eyes as models, we report the expression of iron export proteins ferroportin and ceruloplasmin, and major iron uptake and storage proteins transferrin, transferrin receptor, and ferritin in the ciliary epithelium, indicating active exchange of iron at this site. Ferroportin and transferrin receptor are also expressed in the corneal endothelium. However, the relative expression of iron export and uptake proteins suggests export from the ciliary epithelium and import by corneal endothelium. In addition, abundant expression of PrPC, a ferrireductase that facilitates iron transport, is noted in pigmented and non-pigmented epithelium of the CB, posterior pigmented epithelium of the iris, corneal endothelium and epithelium, and lens epithelium. Notably, majority of PrPC in the ciliary epithelium is cleaved at the ß-site as in retinal pigment epithelial cells, suggesting a role in iron transport. Most of the PrPC in the cornea, however, is full-length, and susceptible to aggregation by intracerebrally inoculated PrP-scrapie, an infectious conformation of PrPC responsible for human and animal prion disorders. Soluble PrPC is present in the aqueous and vitreous humor, a provocative observation with significant implications. Together, these observations suggest independent cycling of iron in the anterior segment, and a prominent role of PrPC in this process. Aggregation of PrPC in the cornea of PrP-scrapie-infected animals raises the alarming possibility of transmission of animal prions through corneal abrasions.

Prion protein modulates glucose homeostasis by altering intracellular iron.

The prion protein (PrPC), a mainly neuronal protein, is known to modulate glucose homeostasis in mouse models. We explored the underlying mechanism in mouse models and the human pancreatic ß-cell line 1.1B4. We report expression of PrPC on mouse pancreatic ß-cells, where it promoted uptake of iron through divalent-metal-transporters. Accordingly, pancreatic iron stores in PrP knockout mice (PrP-/-) were significantly lower than wild type (PrP+/+) controls. Silencing of PrPC in 1.1B4 cells resulted in significant depletion of intracellular (IC) iron, and remarkably, upregulation of glucose transporter GLUT2 and insulin. Iron overloading, on the other hand, resulted in downregulation of GLUT2 and insulin in a PrPC-dependent manner. Similar observations were noted in the brain, liver, and neuroretina of iron overloaded PrP+/+ but not PrP-/- mice, indicating PrPC-mediated modulation of insulin and glucose homeostasis through iron. Peripheral challenge with glucose and insulin revealed blunting of the response in iron-overloaded PrP+/+ relative to PrP-/- mice, suggesting that PrPC-mediated modulation of IC iron influences both secretion and sensitivity of peripheral organs to insulin. These observations have implications for Alzheimer's disease and diabetic retinopathy, known complications of type-2-diabetes associated with brain and ocular iron-dyshomeostasis.

α-Synuclein impairs ferritinophagy in the retinal pigment epithelium: Implications for retinal iron dyshomeostasis in Parkinson's disease.

Retinal degeneration is prominent in Parkinson's disease (PD), a neuromotor disorder associated with aggregation of α-synuclein (α-syn) in the substantia-nigra (SN). Although α-syn is expressed in the neuroretina, absence of prominent aggregates suggests altered function as the likely cause of retinal pathology. We demonstrate that α-syn impairs ferritinophagy, resulting in the accumulation of iron-rich ferritin in the outer retina in-vivo and retinal-pigment-epithelial (RPE) cells in-vitro. Over-expression of Rab1a restores ferritinophagy, suggesting that α-syn impairs lysosomal function by disrupting the trafficking of lysosomal hydrolases. Surprisingly, upregulation of ferritin in RPE cells by exogenous iron in-vitro stimulated the release of ferritin and α-syn in exosomes, suggesting that iron overload due to impaired ferritinophagy or other cause(s) is likely to initiate prion-like spread of α-syn and ferritin, creating retinal iron dyshomeostasis and associated cytotoxicity. Since over-expression of α-syn is a known cause of PD, these results explain the likely cause of PD-associated retinal degeneration.