Eyeless razor clam Sinonovacula constricta discriminates light spectra through opsins to guide Ca2+ and cAMP signaling pathways.

Phototransduction is based on opsins that drive distinct types of Gα cascades. Although nonvisual photosensitivity has long been known in marine bivalves, the underlying molecular basis and phototransduction mechanism are poorly understood. Here, we introduced the eyeless razor clam Sinonovacula constricta as a model to clarify this issue. First, we showed that S. constricta was highly diverse in opsin family members, with a significant expansion in xenopsins. Second, the expression of putative S. constricta opsins was highly temporal-spatio specific, indicating their potential roles in S. constricta development and its peripheral photosensitivity. Third, by cloning four S. constricta opsins with relatively higher expression (Sc_opsin1, 5, 7, and 12), we found that they exhibited different expression levels in response to different light environments. Moreover, we demonstrated that these opsins (excluding Sc_opsin7) couple with Gαq and Gαi cascades to mediate the light-dependent Ca2+ (Sc_opsin1 and 5) and cAMP (Sc_opsin12) signaling pathways. The results indicated that Sc_opsin1 and 5 belonged to Gq-opsins, Sc_opsin12 belonged to Gi-opsins, while Sc_opsin7 might act as a photo-isomerase. Furthermore, we found that the phototransduction function of S. constricta Gq-opsins was dependent on the lysine at the seventh transmembrane domain, and greatly influenced by the external light spectra in a complementary way. Thus, a synergistic photosensitive system mediated by opsins might exist in S. constricta to rapidly respond to the transient or subtle changes of the external light environment. Collectively, our findings provide valuable insights into the evolution of opsins in marine bivalves and their potential functions in nonvisual photosensitivity.

Human cone elongation responses can be explained by photoactivated cone opsin and membrane swelling and osmotic response to phosphate produced by RGS9-catalyzed GTPase.

Human cone outer segment (COS) length changes in response to stimuli bleaching up to 99% of L- and M-cone opsins were measured with high resolution, phase-resolved optical coherence tomography (OCT). Responses comprised a fast phase (∼5 ms), during which COSs shrink, and two slower phases (1.5 s), during which COSs elongate. The slower components saturated in amplitude (∼425 nm) and initial rate (∼3 nm ms-1) and are well described over the 200-fold bleaching range as the sum of two exponentially rising functions with time constants of 80 to 90 ms (component 1) and 1,000 to 1,250 ms (component 2). Measurements with adaptive optics reflection densitometry revealed component 2 to be linearly related to cone pigment bleaching, and the hypothesis is proposed that it arises from cone opsin and disk membrane swelling triggered by isomerization and rate-limited by chromophore hydrolysis and its reduction to membrane-localized all-trans retinol. The light sensitivity and kinetics of component 1 suggested that the underlying mechanism is an osmotic response to an amplified soluble by-product of phototransduction. The hypotheses that component 1 corresponds to G-protein subunits dissociating from the membrane, metabolites of cyclic guanosine monophosphate (cGMP) hydrolysis, or by-products of activated guanylate cyclase are rejected, while the hypothesis that it corresponds to phosphate produced by regulator of G-protein signaling 9 (RGS9)-catalyzed hydrolysis of guanosine triphosphate (GTP) in G protein-phosphodiesterase complexes was found to be consistent with the results. These results provide a basis for the assessment with optoretinography of phototransduction in individual cone photoreceptors in health and during disease progression and therapeutic interventions.

Solar urticaria involves rapid mast cell STAT3 activation and neutrophil recruitment, with FcεRI as an upstream regulator.

BACKGROUND: Solar urticaria is a rare photodermatosis characterized by rapid-onset sunlight-induced urticaria, but its pathophysiology is not well understood. OBJECTIVE: We sought to define cutaneous cellular and molecular events in the evolution of solar urticaria following its initiation by solar-simulated UV radiation (SSR) and compare with healthy controls (HC). METHODS: Cutaneous biopsy specimens were taken from unexposed skin and skin exposed to a single low (physiologic) dose of SSR at 30 minutes, 3 hours, and 24 hours after exposure in 6 patients with solar urticaria and 6 HC. Biopsy specimens were assessed by immunohistochemistry and bulk RNA-sequencing analysis. RESULTS: In solar urticaria specimens, there was enrichment of several innate immune pathways, with striking early involvement of neutrophils, which was not observed in HC. Multiple proinflammatory cytokine and chemokine genes were upregulated (including IL20, IL6, and CXCL8) or identified as upstream regulators (including TNF, IL-1ß, and IFN-γ). IgE and FcεRI were identified as upstream regulators, and phosphorylated signal transducer and activator of transcription 3 expression in mast cells was increased in solar urticaria at 30 minutes and 3 hours after SSR exposure, suggesting a mechanism of mast cell activation. Clinical resolution of solar urticaria by 24 hours mirrored resolution of inflammatory gene signature profiles. Comparison with available datasets of chronic spontaneous urticaria showed transcriptomic similarities relating to immune activation, but several transcripts were identified solely in solar urticaria, including CXCL8 and CSF2/3. CONCLUSIONS: Solar urticaria is characterized by rapid signal transducer and activator of transcription 3 activation in mast cells and involvement of multiple chemotactic and innate inflammatory pathways, with FcεRI engagement indicated as an early event.

Erythropoietic protoporphyrias: Pathogenesis, diagnosis and management.

The erythropoietic protoporphyrias consist of three ultra-rare genetic disorders of the erythroid heme biosynthesis, including erythropoietic protoporphyria (EPP1), X-linked protoporphyria (XLEPP) and CLPX-protoporphyria (EPP2), which all lead to the accumulation of protoporphyrin IX (PPIX) in erythrocytes. Affected patients usually present from early childhood with episodes of severe phototoxic pain in the skin exposed to visible light. The quantification of PPIX in erythrocytes with a metal-free PPIX ≥3 times the upper limit of normal confirms the diagnosis. Protoporphyria-related complications include liver failure, gallstones, mild anaemia and vitamin D deficiency with reduced bone mineral density. The management is focused on preventing phototoxic reactions and treating the complications. Vitamin D should be supplemented, and DEXA scans in adults should be considered. In EPP1, even in cases of biochemically determined iron deficiency, supplementation of iron may stimulate PPIX production, resulting in an increase in photosensitivity and the risk of cholestatic liver disease. However, for patients with XLEPP, iron supplementation can reduce PPIX levels, phototoxicity and liver damage. Because of its rarity, there is little data on the management of EPP-related liver disease. As a first measure, any hepatotoxins should be eliminated. Depending on the severity of the liver disease, phlebotomies, exchange transfusions and ultimately liver transplantation with subsequent haematopoietic stem cell transplantation (HSCT) are therapeutic options, whereby multidisciplinary management including porphyria experts is mandatory. Afamelanotide, an alpha-melanocyte-stimulating hormone analogue, is currently the only approved specific treatment that increases pain-free sunlight exposure and quality of life.

Headache in systemic lupus erythematosus: The LUNA registry cross-sectional study.

OBJECTIVES: This study investigated the clinically relevant factors for headaches in patients with systemic lupus erythematosus (SLE) using a registry from a Japanese multicenter cohort. METHODS: This cross-sectional study analysed the clinical information of patients with SLE who experienced headache episodes using the Migraine Disability Assessment (MIDAS) questionnaire. Significant findings in the comparisons between patients with headache (HA patients) and those without headache (non-HA patients) and in the comparisons depending on the grades of headache-induced disability in daily life based on the MIDAS scores were evaluated. Multivariate logistic regression analyses were performed to identify the relevant factors for headache. RESULTS: We analyzed 369 patients (median age, 45 years; female, 90.8%), including 113 HA patients who were significantly younger than non-HA patients (p < .005). HA patients had significantly higher frequencies of photosensitivity, rashes, and mucosal ulcers than non-HA patients (p < .05). Age and photosensitivity were significantly associated with headache (odds ratio (OR) 0.93, 95% confidence interval (CI) 0.95-0.99; OR 2.11, 95% CI 1.29-3.49, respectively). In the HA patients, hypocomplementemia was significantly associated with a disability of more than mild grade (OR 2.89, 95% CI 1.14-7.74), while rash was significantly observed in those presenting with moderate and severe disability. CONCLUSION: This study suggests that photosensitivity is a relevant manifestation of headache in patients with SLE. Persistent hypocomplementemia can contribute to headache-induced disability in daily life, whereas a rash may be a dominant manifestation in patients presenting with moderate/severe headache-induced disability.

Tunable photo-response in the visible to NIR spectrum range of Germanium-based junctionless nanowire transistor.

In this paper, the phototransistor behavior is investigated in the germanium-on-insulator (GeOI)-based junctionless nanowire (JL-NW) transistor under various light conditions. High responsivity and photosensitivity are attributed in the fully depleted regime within the visible and near-infrared bands. The impact of light is also investigated in detail on the electronic and transfer characteristics such as energy bandgap, carrier distribution, electrostatic potential, electric field, and generation and recombination rates. Further, the channel doping and thickness are tuned to optimize the optical responsivity. The significant tunability of responsivity is observed with increasing channel thickness. The device exhibits fast optical switching performance, which is further enhanced at higher input light power. Overall, at the nanoscale dimension, our proposed phototransistor demonstrates better detectivity with a significantly smaller illumination area. Thus, the GeOI-based JL-NW phototransistors can be used for imaging (visible wavelength range) and bioimaging (near-infrared wavelength range) applications in advanced technology nodes.

Continuum of light sensitivity in atopic dermatitis: A retrospective analysis of 139 cases in Scotland.

BACKGROUND: Previous reports have characterized photosensitivity in atopic dermatitis (AD), but with differences in terminology and criteria. OBJECTIVE: This study aims to assess outcomes in 139 patients with AD referred for photodiagnostic testing and to establish diagnostic criteria for photosensitivity in AD. METHODS: Clinical and photodiagnostic data were reviewed, categorizing photosensitivity into photoexacerbated AD, photosensitive AD, and chronic actinic dermatitis. RESULTS: Of the patient cohort, the mean age was 42.6 ± 16.7 years, and 61.9% were men. In total, 51.1% of the patients with photoexacerbated AD had normal monochromator phototesting, and 7.9% of the patients with photosensitive AD displayed slight-to-moderate ultraviolet (UV)-A sensitivity (≥30% of normal minimal erythema dose [MED]) and mostly normal or slightly reduced UV-B MEDs (≥80% of normal MED). Conversely, 41% of the patients had chronic actinic dermatitis, and 93% of this group demonstrated significant UV-B sensitivity, with very low UV-B MEDs (<80% of normal MED) and/or very low UV-A MEDs (<30% of normal MED). No significant differences in sex, age, or skin phototype were observed between the groups. Serial phototesting revealed changes in photosensitivity status over time in 8 patients. LIMITATIONS: A small sample size and retrospective design. CONCLUSIONS: This study highlights the heterogeneity of photosensitivity patterns in patients with AD and the importance of follow-up assessments due to potential shifts in disease spectrum over time.

Sunproofing from within: A deep dive into oral photoprotection strategies in dermatology.

BACKGROUND: Photoprotection is the first measure in the prevention and treatment of the deleterious effects that sunlight can cause on the skin. It is well known that prolonged exposure to solar radiation leads to acute and chronic complications, such as erythema, accelerated skin aging, proinflammatory and procarcinogenic effects, and eye damage, among others. METHODS: A better understanding of the molecules that can protect against ultraviolet radiation and their effects will lead to improvements in skin health. RESULTS: Most of these effects of the sunlight are modulated by oxidative stress and proinflammatory mechanisms, therefore, the supplementation of substances that can regulate and neutralize reactive oxygen species would be beneficial for skin protection. Current evidence indicates that systemic photoprotection should be used as an adjunctive measure to topical photoprotection. CONCLUSION: Oral photoprotectors are a promising option in improving protection against damage induced by UVR, as they contain active ingredients that increase the antioxidant effects of the body, complementing other photoprotection measures. We present a review of oral photoprotectors and their effects.

Light Therapy in Chronic Migraine.

PURPOSE OF REVIEW: This review assesses the effectiveness and safety of light therapy, particularly green light therapy, as an emerging non-pharmacological treatment for chronic migraine (CM). It aims to highlight alternative or complementary approaches to traditional pharmacological remedies, focusing the need for diverse treatment options. RECENT FINDINGS: Despite sensitivity to light being a defining feature of migraine, light therapy has shown promising signs in providing substantial symptom relief. Studies have provided insights into green light therapy's role in managing CM. These studies consistently demonstrate its efficacy in reducing the frequency, severity, and symptoms of migraines. Additional benefits observed include improvements in sleep quality and reductions in anxiety. Importantly, green light therapy has been associated with minimal side effects, indicating its potential as a suitable option for migraine sufferers. In addition to green light, other forms of light therapy, such as infrared polarized light, low-level laser therapy (LLLT), and intravascular irradiation of blood (ILIB), are also being explored with potential therapeutic effects. Light therapies, especially green light therapy, are recognized as promising, safe, and non-pharmacological interventions for treating CM. They have been shown to be effective in decreasing headache frequency and enhancing the overall quality of life. However, current studies, often limited by small sample sizes, prompt more extensive clinical trials to better understand the full impact of light therapies. The exploration of other light-based treatments, such as LLLT and ILIB, warrants further research to broaden the scope of effective migraine management strategies.

Pharmacokinetics-Based Safety Evaluation in Half-Dose Verteporfin Photodynamic Therapy.

INTRODUCTION: This study was conducted to assess the systemic pharmacokinetic profiles of half-dose verteporfin photodynamic therapy (PDT) using concentration data from a previous clinical trial and to subsequently suggest safety precaution guidelines. METHODS: Coefficients for the bi-exponential model were obtained from published data on post-infusion plasma verteporfin concentrations within a period of 0.17-4 h. Using the extrapolative forecasting method, we plotted the 48-h post-verteporfin plasma concentration model. The time required to achieve a comparable level of verteporfin 48 h after a conventional dose (6 mg/m2 body surface area, BSA) infusion was calculated for a half-dose infusion (3 mg/m2 BSA). RESULTS: At 24 and 48 h post-verteporfin infusion, the plasma concentration following the conventional dose was 1.28 × 10-4 µg/mL and 5.06 × 10-8 µg/mL, compared to 3.57 × 10-5 µg/mL and 7.54 × 10-9 µg/mL for the half-dose PDT, representing concentrations that were 3.6 times and 6.7 times higher, respectively. The estimated time required to attain the same level of verteporfin 48 h after a conventional dose was calculated as 42-h post-half-dose PDT. CONCLUSIONS: The results of this study indicate that precautionary measures should be taken to avoid sunlight following both half and conventional doses of PDT during the similar post-treatment periods of two days. Nevertheless, given the substantially higher plasma concentration levels associated with conventional-dose PDT compared with the half-dose, systemic safety should be carefully considered when administering conventional-dose PDT.

Photopatch testing: Clinical characteristics, test results, and final diagnoses from the North American Contact Dermatitis Group, 2009-2020.

BACKGROUND: Photoallergic contact dermatitis (PACD) is a delayed hypersensitivity reaction to allergens only in the presence of ultraviolet radiation in sunlight. Photopatch testing (PhotoPT) is necessary to confirm the diagnosis of PACD. There are few published studies of PhotoPT in North America. OBJECTIVE: To summarise the results of patients photopatch tested by members of the North American Contact Dermatitis Group (NACDG), 2009-2020. METHODS: Retrospective analysis of patient characteristics and PhotoPT results to 32 allergens on the NACDG Photopatch Test Series. RESULTS: Most of the 454 tested patients were female (70.3%), 21-60 years old (66.7%) and White (66.7%). There were a total of 119 positive photopatch tests. Sunscreen agents comprised 88.2% of those, with benzophenones responsible for over half of them. Final diagnoses included PACD in 17.2%, allergic contact dermatitis (ACD) in 44.5%, polymorphous light eruption (PMLE) in 18.9% and chronic actinic dermatitis (CAD) in 9.0% of patients. CONCLUSIONS: In 454 patients with suspected photosensitivity referred for photopatch testing in North America, approximately one-fifth had PACD. Sunscreen agents, especially benzophenones, were the most common photoallergens. Other common diagnoses included ACD, PMLE and CAD. Photopatch testing is an important tool for differentiating these conditions.

Congenital Erythropoietic Porphyria: A Case of Hepatic Failure and Angioedema Following Ferrous Sulfate Supplementation.

This report describes an unusual case of a young anemic female who experienced acute hepatic insufficiency and angioedema after ferrous sulfate consumption. Her primary diagnosis of congenital erythropoietic porphyria (CEP) was revealed after a detailed dermatologic examination and laboratory data. The patient was treated with IV methylprednisolone along with red blood cell transfusion, vitamin supplementation, and wound care. Our case report emphasizes the importance of physician awareness of CEP since it is a rare disease that tends to mimic other chronic porphyrias, various drug reactions, and collagenopathies.

Elucidating disparities in sunscreen coverage among state Medicaid preferred drug lists.

Regular application of over-the-counter (OTC) sunscreen is considered the foundation of skin cancer prevention, yet OTC sunscreen is not eligible for reimbursement in almost all state Medicaid benefit plans. On review of 111 Medicaid preferred drug lists (PDLs) across 50 states and the District of Columbia (DC), only five plans were identified that incorporate coverage of sunscreen. Thus, many recipients of Medicaid, the majority of whom are individuals and families of lower socioeconomic status, may encounter financial difficulty and thus forego utilizing sun protective measures due to financial constraints. Here, we compare current Medicaid coverage of OTC sunscreen and discuss calculated and theoretical annual costs of this skin cancer prevention method.

Photosensitive Control and Network Synchronization of Chemical Oscillators.

The Belousov-Zhabotinsky (BZ) reaction has long been a paradigmatic system for studying chemical oscillations. Here, we experimentally studied the synchronization control within photochemically coupled star networks of BZ oscillators. Experiments were carried out in wells performed in soda-lime glass constructed using novel laser technologies. Utilizing the inherent oscillatory nature of the BZ reaction, we engineered a star network of oscillators interconnected through photochemical inhibitory coupling. Furthermore, the experimental setup presented here could be extrapolated to more complex network architectures with both excitatory and inhibitory couplings, contributing to the fundamental understanding of synchronization in complex systems.

Rethinking Opsins.

Opsins, the protein moieties of animal visual photo-pigments, have emerged as moonlighting proteins with diverse, light-dependent and -independent physiological functions. This raises the need to revise some basic assumptions concerning opsin expression, structure, classification, and evolution.

Prevalence, characteristics, and knowledge related to photosensitivity in patients with lupus erythematosus: the international PHOTOLUP study.

OBJECTIVES: To assess the prevalence, characteristics and knowledge about photosensitivity and the use of photoprotective measures in an international cohort of cutaneous and systemic lupus erythematosus patients. METHODS: We conducted an international, cross-sectional study based on a 46-question web-based survey including patients with medically confirmed LE conducted between November 2021 and April 2022. RESULTS: 600 patients with lupus erythematosus (94% female, median age: 41 years [IQR: 33-51]) from 50 countries were included. A history of photosensitivity was reported by 389/600 (64.8%) patients. Photosensitivity was associated with the presence of other cutaneous involvement (OR = 3.8; 95%CI 2.5-5.7; p < 0.001) and differed according to the area of habits and level of education (p < 0.001, for all). Photosensitivity was characterized by a wide range of clinical manifestations (both cutaneous and systemic symptoms in 56.1% and systemic symptoms only in 29.8% of patients). Fatigue was the most frequently reported systemic manifestation (82.3%). Overall, 559/600 (93%) patients were aware of the detrimental role of UV exposure in lupus erythematosus, but 160/480 (33.3%) were unaware of the importance of photoprotective measures, including 90/310 (29%) among those with photosensitivity. CONCLUSION: A high rate of self-reported photosensitivity characterize lupus erythematosus patients. Photosensitivity frequently includes subjective features, which makes it difficult to evaluate in clinical practice. As fatigue is frequent in LE, further study is needed to clarify its causal link with UV exposure. About one-third of lupus erythematosus patients are unaware of the importance of photoprotective measures. This should be improved through more frequent and targeted awareness interventions.

Phototesting in erythropoietic protoporphyria trials: A systematic review.

Severe skin pain when exposed to long wave ultraviolet radiation or visible light is the main symptom of erythropoietic protoporphyria (EPP). Treatment options for EPP are inadequate and new treatments are needed but hampered by the lack of valid efficacy outcomes. Phototesting with well-defined illumination of the skin can be performed reliably. We aimed to provide an overview of phototest procedures used to evaluate EPP treatments. Systematic searches of Embase, MEDLINE and the Cochrane Library were performed. Searches identified 11 studies using photosensitivity as efficacy outcome. The studies used eight different phototest protocols. Illuminations were performed with a filtered high-pressure mercury arc, or a xenon arc lamp equipped with monochromator or filters. Some used broadband, others narrowband illumination. In all protocols phototests were performed on the hands or the back. Endpoints were minimal dose required to induce either first symptom of discomfort, erythema, urticaria or intolerable pain. Other endpoints were change in erythema intensity or diameter of any type of flare after exposure compared to before. In conclusion, protocols displayed extensive variability in illumination set-up and evaluation of phototest reactions. Implementation of a standardized phototest method will allow more consistent and reliable outcome evaluation in future therapeutic research of protoporphyric photosensitivity.

Sex-based electroclinical differences and prognostic factors in epilepsy with eyelid myoclonia.

Although a striking female preponderance has been consistently reported in epilepsy with eyelid myoclonia (EEM), no study has specifically explored the variability of clinical presentation according to sex in this syndrome. Here, we aimed to investigate sex-specific electroclinical differences and prognostic determinants in EEM. Data from 267 EEM patients were retrospectively analyzed by the EEM Study Group, and a dedicated multivariable logistic regression analysis was developed separately for each sex. We found that females with EEM showed a significantly higher rate of persistence of photosensitivity and eye closure sensitivity at the last visit, along with a higher prevalence of migraine with/without aura, whereas males with EEM presented a higher rate of borderline intellectual functioning/intellectual disability. In female patients, multivariable logistic regression analysis revealed age at epilepsy onset, eyelid myoclonia status epilepticus, psychiatric comorbidities, and catamenial seizures as significant predictors of drug resistance. In male patients, a history of febrile seizures was the only predictor of drug resistance. Hence, our study reveals sex-specific differences in terms of both electroclinical features and prognostic factors. Our findings support the importance of a sex-based personalized approach in epilepsy care and research, especially in genetic generalized epilepsies.

L-arginine and aged garlic extract for the prevention of migraine: a study protocol for a randomised, double-blind, placebo-controlled, phase-II trial (LARGE trial).

BACKGROUND: Migraine is a common and distressing neurological condition characterised by recurrent throbbing headaches, nausea and heightened sensitivity to light and sound. Accumulating evidence suggests that cerebral arteries dilate during migraine, causing distal microvessels to constrict, which could activate nociceptors and cause onset of headache pain. If so, preventing or attenuating chronic microvascular constriction, and promoting a dilatory phenotype, may reduce frequency and/or severity of migraines. The primary aim of the L-Arginine and Aged Garlic Extract (LARGE) trial is to investigate whether oral treatment with dietary nutraceuticals, L-arginine and aged garlic extract (AGE), both systemic vasodilatory agents, will alleviate migraine frequency, duration and severity in adults with chronic frequent episodic migraines. METHODS: The study is a randomised double-blind placebo-controlled phase-II single-site clinical trial conducted in Perth, Australia. The target sample is to recruit 240 participants diagnosed with chronic frequent episodic migraines between 18 and 80 years of age. Participants will be randomised to one of four treatment groups for 14 weeks (placebo induction for 2 weeks, followed by 12 weeks on one of the respective treatment arms): placebo, L-arginine, AGE, or a combination of L-arginine and AGE. The doses of L-arginine and AGE are 1.5 g and 1 g daily, respectively. The primary outcome is to assess migraine response using change in migraine frequency and intensity between baseline and 12 weeks. Secondary outcomes include the impact of L-arginine and/or AGE on photosensitivity, retinal vessel changes, and blood biomarker concentrations of vascular tone, following a 12-week intervention. DISCUSSION: The protocol describes the oral administration of 2 nutraceutical-based interventions as possible prophylactic treatments for chronic frequent episodic migraines, with potential for direct clinical translation of outcomes. Potential limitations of the study include the fixed-dose design of each treatment arm and that in vivo neuroimaging methods, such as magnetic resonance imaging (MRI), will not be conducted to determine putative cerebro-vasodilatory changes to coincide with the outcome measures. Dose-response studies may be indicated. TRIAL REGISTRATION: The trial was retrospectively registered with the Australian New Zealand Clinical Trials Registry ACTRN12621001476820 (Universal Trial Number: U1111-1268-1117) on 04/08/2021. This is protocol version 1, submitted on 25/11/2022.

Brivaracetam or levetiracetam in status epilepticus?: Lessons from the photosensitivity model.

First, a short history is given of the use of the EEG as a biomarker of efficacy in anti-seizure medication (ASM) development. The generalized epileptiform EEG response to Intermittent Photic Stimulation (IPS), the photoparoxysmal EEG response or PPR, in particular, is a reliable reproducible measure since the 1950s. Over time, a "Photosensitivity Model", testing within the same patients the impact of potential new oral ASMs, along with dose-ranging data, on PPRs, has been developed successfully. The classical Photosensitivity Model consists of IPS and blood sampling for ASM measurement performed hourly between 8 AM and 5 PM over three consecutive days. This single-blind, placebo-controlled, pharmacokinetic-pharmacodynamic (PK/PD) Model is now commonly utilized as a Proof-of-Concept Phase 2a trial. For Generalized Tonic-Clonic Status Epilepticus (GTCSE), it is especially relevant to know the time for CNS entry and effect minutes after i.v. ASM treatment, since "time is brain". We, therefore, adapted successfully the Model to a time-efficient Model with the determination of photosensitivity ranges in minutes after equivalent doses of iv brivaracetam (BRV) and levetiracetam (LEV). This modified design allows one to monitor the time to CNS effect (i.e., PPR elimination) of a quickly-acting FDA-approved ASM given i.v., a crucial element in status epilepticus treatment. This paper was presented at the 8th London-Innsbruck Colloqium on Status Epilepticus and Acute Seizures held in September 2022.