Long-term efficacy and safety of XEN-45 gel stent implantation in patients with normal-tension glaucoma.

BACKGROUND: Minimally invasive bleb surgery using the XEN-45 gel stent has not been established for the treatment of normal-tension glaucoma (NTG). The main objective of this study was to evaluate the long-term treatment efficacy and safety of XEN-45 in eyes with uncontrolled NTG. METHODS: A retrospective analysis of patients with NTG who underwent XEN-45 gel stent implantation at university hospital Tuebingen between 2016 and 2021. The primary outcome measure was surgical success after three years defined as lowering of intraocular pressure (IOP) of ≥ 20%, with target IOP between 6 and 15 mmHg. Success was complete without and qualified irrespective of topical antiglaucoma medication use. The need for further glaucoma surgery, except for needling, was regarded as a failure. The secondary outcome measures included changes in mean IOP, number of antiglaucoma medications, and needling and complication rates. RESULTS: Twenty-eight eyes from 23 patients were included in the final analysis. Complete and qualified success rates were 56.5% and 75% after three years, respectively. Mean postoperative IOP ± standard deviation decreased significantly after three years from 19.3 ± 2.0 mmHg at baseline to 13.7 ± 4.2 mmHg (n = 22; p < 0.0001). The median number of antiglaucoma medications decreased from 2 (range 0-4) to 0 after three years (range 0-3; p < 0.0001). Sixteen eyes (57%) required a median of 1 (range 1-3) needling procedures. One eye required further glaucoma surgery. No sight-threatening complications were observed. CONCLUSION: The XEN-45 stent is effective and safe for the long-term treatment of NTG. However, needling was frequently required to improve outcomes.

Automated Measurement and Three-Dimensional Fitting of Corneal Ulcerations and Erosions via AI-Based Image Analysis.

PURPOSE: Artificial intelligence (AI)-tools hold great potential to compensate for missing resources in health-care systems but often fail to be implemented in clinical routine. Intriguingly, no-code and low-code technologies allow clinicians to develop Artificial intelligence (AI)-tools without requiring in-depth programming knowledge. Clinician-driven projects allow to adequately identify and address real clinical needs and, therefore, hold superior potential for clinical implementation. In this light, this study aimed for the clinician-driven development of a tool capable of measuring corneal lesions relative to total corneal surface area and eliminating inaccuracies in two-dimensional measurements by three-dimensional fitting of the corneal surface. METHODS: Standard slit-lamp photographs using a blue-light filter after fluorescein instillation taken during clinical routine were used to train a fully convolutional network to automatically detect the corneal white-to-white distance, the total fluorescent area and the total erosive area. Based on these values, the algorithm calculates the affected area relative to total corneal surface area and fits the area on a three-dimensional representation of the corneal surface. RESULTS: The developed algorithm reached dice scores >0.9 for an automated measurement of the relative lesion size. Furthermore, only 25% of conventional manual measurements were within a ± 10% range of the ground truth. CONCLUSIONS: The developed algorithm is capable of reliably providing exact values for corneal lesion sizes. Additionally, three-dimensional modeling of the corneal surface is essential for an accurate measurement of lesion sizes. Besides telemedicine applications, this approach harbors great potential for clinical trials where exact quantitative and observer-independent measurements are essential.

User Friendliness and Perioperative Guidance Benefits of a Cataract Surgery Education App: Randomized Controlled Trial.

BACKGROUND: Cataract surgeries are among the most performed surgeries worldwide. A thorough patient education is essential to inform patients about the perioperative process and postoperative target results concerning the intraocular lens and objectives for visual outcomes. However, addressing all relevant aspects and questions is time-consuming. Mobile apps can facilitate this process for both patients and physicians and thus be beneficial. However, the success of such an app depends on its user friendliness and acceptance by patients. OBJECTIVE: This study aimed to evaluate the user friendliness and acceptance of a cataract surgery education app on mobile devices among patients undergoing cataract surgery, the characteristics of patients who benefit the most from app use, and the influence of the app on patient satisfaction with treatment. METHODS: All patients who underwent cataract surgery at an ophthalmological practice from August 2020 to July 2021 were invited to participate in this randomized controlled trial. Out of 493 invited patients, 297 (60.2%) were enrolled in this study. Patients were randomized into 3 different groups. Half of the patients were offered to participate in Group 1 with use of the "Patient Journey" app. However, if they decided not to use the app, they were included in Group 2 (app denial). The other half of the patients were included in Group 3 (control) with no use of the app and with information provided conventionally. The app provided general information on the ophthalmological center, surgeons, cataract, and treatment options. Different questionnaires were used in all 3 groups to evaluate satisfaction with the perioperative process. Group 1 evaluated the app. Demographic characteristics, such as age, gender, and educational degree, were assessed. RESULTS: Group 1 included 77 patients (median age 69 years). Group 2 included 61 patients, and their median age was higher (median age 79 years). Group 3 included 159 patients (median age 74 years). There was no difference in satisfaction with the perioperative process and clinic between the 3 groups. Almost all app users appreciated the digital details provided for the organization and the information on the surgery. Age did not play a major role in appreciation of the app. Female patients tended to appreciate the information provided more than male patients. Patients who did not have a higher university degree experienced more benefits from the informational content of the app and were the most satisfied with the information. However, male patients and academics were in general more aware of technology and handled the app more easily. CONCLUSIONS: The app showed high user friendliness and acceptance, and could particularly benefit specific patient groups. App users demonstrated a noninferior high satisfaction with the treatment in the ophthalmological center in comparison with patients who were informed about the surgery only conventionally.

Restoring vision after cat bite: a case report on successful diagnostic and therapeutic regimen for Capnocytophaga endophthalmitis.

BACKGROUND: Capnocytophaga is a bacterium frequently found in the oral flora of dogs and cats (e.g. Capnocytophaga canimorsus) and humans (e.g. Capnocytophaga gingivalis). Among Capnocytophaga related ocular infections, fulminant endophthalmitis is a rare but sight-threatening clinical manifestation. CASE PRESENTATION: A 35-year-old previously healthy patient presented after a cat bite into the left upper and lower eyelid and nasal part of the conjunctiva of the left eye. At initial consultation, the corrected visual acuity was 0.8 in decimal scale and a detailed clinical examination revealed no evidence of ocular penetration. However, daily follow-up examinations under local therapy revealed a progressive intraocular inflammation, therefore the decision was made to perform a diagnostic vitrectomy with intravitreal and systemic antibiotic treatment. Capnocytophaga felis was detected as the cause of endophthalmitis and the initiated treatment resulted in quick morphological and functional recovery of the left eye. After surgery of secondary cataract, visual acuity improved from hand motion preoperatively to 1.0 postoperatively. CONCLUSIONS: Early recognition as well as prompt and effective treatment of animal bite associated endophthalmitis is essential for good visual recovery and functional outcome. Furthermore, this case highlights the importance of daily follow-up examinations, even in the absence of signs of ocular penetration and intraocular inflammation, to enable prompt and effective treatment initiation. Given the negative results in bacterial culture, we additionally emphasize the value of sequencing-based microbiological diagnostics in unclear cases.

A morphometric analysis of the retinal arterioles with adaptive optics imaging in RPE65-associated retinal dystrophy after treatment with voretigene neparvovec.

PURPOSE: To investigate the changes in retinal arterial architecture after treatment with voretigene neparvovec in patients with retinal dystrophy caused by bi-allelic mutations in the RPE65 gene. METHODS: Sixteen eyes treated with voretigene neparvovec at the University Eye Clinic in Tuebingen, Germany, underwent adaptive optics ophthalmoscopy (AO) imaging at baseline and 2 weeks, 1, 3, 6 and 12 months after treatment. Follow-up was performed in six eyes of four patients. For each eye, five different positions at arterial vessels were selected and the wall-to-lumen ratio (WLR), the lumen diameter (LD) and the wall cross-sectional area (WCSA) were measured by the manufacturer's software over the observational period. RESULTS: Vast retinal atrophy dominated all gained AO images. WLR fluctuated in the observation period without statistically significant change. LD and WCSA changed significantly after 2 weeks from the baseline examination and returned to values similar to baseline thereafter. There were no signs of inflammation such as macrophages or perivascular accumulated fluid visible. CONCLUSION: AO imaging of the retinal vessels in RPE65-associated retinal dystrophies (IRD) is challenging. There was no change in the retinal arterial vasculature over the observation period of 12 months that would indicate inflammatory changes. Decrease of the LD and WCSA shortly after treatment might be caused by the perioperative prednisolone intake. AO of retinal vessels can be used as a diagnostic module to complement monitoring the disease and effects of genetic treatments if the acquisition is possible in selected cases.

The Noncanonical Role of Complement Factor H in Retinal Pigment Epithelium (RPE) Cells and Implications for Age-Related Macular Degeneration (AMD).

Age-related macular degeneration (AMD) is a complex degenerative disease of the retina. Dysfunction of the retinal pigment epithelium (RPE) occurs in early stages of AMD, and progressive RPE atrophy leads to photoreceptor death and visual impairments that ultimately manifest as geographic atrophy (GA), one of the late-stage forms of AMD. AMD is caused by a combination of risk factors including aging, lifestyle choices, and genetic predisposition. A gene variant in the complement factor H gene (CFH) that leads to the Y402H polymorphism in the factor H protein (FH) confers the second highest risk for the development and progression of AMD. FH is a major negative regulator of the alternative pathway of the complement system, and the FH Y402H variant leads to increased complement activation, which is detectable in AMD patients. For this reason, various therapeutic approaches targeting the complement system have been developed, however, so far with very limited or no efficacy. Interestingly, recent studies suggest roles for FH beyond complement regulation. Here, we will discuss the noncanonical functions of FH in RPE cells and highlight the potential implications of those functions for future therapeutic approaches.

Patient Reported and Clinical Outcomes after High-Dose Chemotherapy and Autologous Stem Cell Transplantation in Primary Central Nervous System Lymphoma.

Primary central nervous system lymphomas (PCNSL) are rare and associated with an adverse prognosis. High-dose chemotherapy followed by autologous stem cell transplantation (HDC/ASCT) improves progression free (PFS) and overall survival (OS) but neurocognition, performance status and quality of life (QoL) in patient-reported outcome (PRO) after HDC/ASCT remains underexplored. Especially elderly patients may insufficiently recover from this demanding therapy. Therefore, this single-center analysis investigated all PCNSL patients who received HDC/ASCT at the University Hospital Tübingen from 2006-2021 (n = 40, median age 60.5 years) in a retrospective manner. The 2-year PFS/OS was 78.7%/77.3%, respectively, without significant differences between the tested age-groups (≤60 vs. >60 years, p = 0.531/p = 0.334). Higher Thiotepa dosage was an independent predictor for better OS (p = 0.018). Additionally, a one-time prospective, cross-sectional analysis after HDC/ASCT in the same cohort was performed (n = 31; median follow-up 45 months). Here, the median ECOG improved by HDC/ASCT from 1 to 0 and mini-mental state examinations revealed unimpaired neurocognitive functioning (median 28 pts.). PRO data collected by EORTC QLQ-C30 showed a good QoL in both age groups with an average global health status (GHS) of 68.82% (≤60y: 64.72%, >60y: 74.14%). Together, our data indicate that HDC/ASCT is an effective therapy with respect to disease control, overall health status and quality of life, irrespective of patient age.

10q26 - The enigma in age-related macular degeneration.

Despite comprehensive research efforts over the last decades, the pathomechanisms of age-related macular degeneration (AMD) remain far from being understood. Large-scale genome wide association studies (GWAS) were able to provide a defined set of genetic aberrations which contribute to disease risk, with the strongest contributors mapping to distinct regions on chromosome 1 and 10. While the chromosome 1 locus comprises factors of the complement system with well-known functions, the role of the 10q26-locus in AMD-pathophysiology remains enigmatic. 10q26 harbors a cluster of three functional genes, namely PLEKHA1, ARMS2 and HTRA1, with most of the AMD-associated genetic variants mapping to the latter two genes. High linkage disequilibrium between ARMS2 and HTRA1 has kept association studies from reliably defining the risk-causing gene for long and only very recently the genetic risk region has been narrowed to ARMS2, suggesting that this is the true AMD gene at this locus. However, genetic associations alone do not suffice to prove causality and one or more of the 14 SNPs on this haplotype may be involved in long-range control of gene expression, leaving HTRA1 and PLEKHA1 still suspects in the pathogenic pathway. Both, ARMS2 and HTRA1 have been linked to extracellular matrix homeostasis, yet their exact molecular function as well as their role in AMD pathogenesis remains to be uncovered. The transcriptional regulation of the 10q26 locus adds an additional level of complexity, given, that gene-regulatory as well as epigenetic alterations may influence expression levels from 10q26 in diseased individuals. Here, we provide a comprehensive overview on the 10q26 locus and its three gene products on various levels of biological complexity and discuss current and future research strategies to shed light on one of the remaining enigmatic spots in the AMD landscape.

mTOR Inhibition via Rapamycin Treatment Partially Reverts the Deficit in Energy Metabolism Caused by FH Loss in RPE Cells.

Age-related macular degeneration (AMD) is a complex degenerative disease of the retina with multiple risk-modifying factors, including aging, genetics, and lifestyle choices. The combination of these factors leads to oxidative stress, inflammation, and metabolic failure in the retinal pigment epithelium (RPE) with subsequent degeneration of photoreceptors in the retina. The alternative complement pathway is tightly linked to AMD. In particular, the genetic variant in the complement factor H gene (CFH), which leads to the Y402H polymorphism in the factor H protein (FH), confers the second highest risk for the development and progression of AMD. Although the association between the FH Y402H variant and increased complement system activation is known, recent studies have uncovered novel FH functions not tied to this activity and highlighted functional relevance for intracellular FH. In our previous studies, we show that loss of CFH expression in RPE cells causes profound disturbances in cellular metabolism, increases the vulnerability towards oxidative stress, and modulates the activation of pro-inflammatory signaling pathways, most importantly the NF-kB pathway. Here, we silenced CFH in hTERT-RPE1 cells to investigate the mechanism by which intracellular FH regulates RPE cell homeostasis. We found that silencing of CFH results in hyperactivation of mTOR signaling along with decreased mitochondrial respiration and that mTOR inhibition via rapamycin can partially rescue these metabolic defects. To obtain mechanistic insight into the function of intracellular FH in hTERT-RPE1 cells, we analyzed the interactome of FH via immunoprecipitation followed by mass spectrometry-based analysis. We found that FH interacts with essential components of the ubiquitin-proteasomal pathway (UPS) as well as with factors associated with RB1/E2F signalling in a complement-pathway independent manner. Moreover, we found that FH silencing affects mRNA levels of the E3 Ubiquitin-Protein Ligase Parkin and PTEN induced putative kinase (Pink1), both of which are associated with UPS. As inhibition of mTORC1 was previously shown to result in increased overall protein degradation via UPS and as FH mRNA and protein levels were shown to be affected by inhibition of UPS, our data stress a potential regulatory link between endogenous FH activity and the UPS.

CFH Loss in Human RPE Cells Leads to Inflammation and Complement System Dysregulation via the NF-κB Pathway.

Age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, is a degenerative disease of the macula, where retinal pigment epithelium (RPE) cells are damaged in the early stages of the disease, and chronic inflammatory processes may be involved. Besides aging and lifestyle factors as drivers of AMD, a strong genetic association to AMD is found in genes of the complement system, with a single polymorphism in the complement factor H gene (CFH), accounting for the majority of AMD risk. However, the exact mechanism of CFH dysregulation confers such a great risk for AMD and its role in RPE cell homeostasis is unclear. To explore the role of endogenous CFH locally in RPE cells, we silenced CFH in human hTERT-RPE1 cells. We demonstrate that endogenously expressed CFH in RPE cells modulates inflammatory cytokine production and complement regulation, independent of external complement sources, or stressors. We show that loss of the factor H protein (FH) results in increased levels of inflammatory mediators (e.g., IL-6, IL-8, GM-CSF) and altered levels of complement proteins (e.g., C3, CFB upregulation, and C5 downregulation) that are known to play a role in AMD. Moreover, our results identify the NF-κB pathway as the major pathway involved in regulating these inflammatory and complement factors. Our findings suggest that in RPE cells, FH and the NF-κB pathway work in synergy to maintain inflammatory and complement balance, and in case either one of them is dysregulated, the RPE microenvironment changes towards a proinflammatory AMD-like phenotype.

Prion Protein on Human Leukocytes Is Reduced in Iron Deficiency - Possible Implications for Age-related Macular Degeneration?

MATERIALS AND METHODS: Patients presenting to the department of ophthalmology of the Medical University of Graz for reasons unrelated to prion diseases were enrolled. Parameters of iron metabolism, including ferritin and soluble transferrin receptor were measured by routine laboratory tests. Serum prion protein was determined by enzyme-linked immunosorbent assay. Surface prion protein on CD14+ monocytes and CD4+ T cells was analyzed by fluorescence activated cell sorting. RESULTS: 95 patients were enrolled. Soluble transferrin receptor correlated significantly with prion protein levels on CD14+POM1+ monocytes (P = .001, r = -0.7) and on CD4+POM1+ T cells (P = .01, r = -0.62). CONCLUSION: Our findings suggest a connection between the physiological function of the prion protein and iron metabolism in humans.

Medication use and driving patterns in older drivers: preliminary findings from the LongROAD study.

BACKGROUND: The potential for impaired driving due to medication use can occur at any age, though older adults are more likely to take multiple prescribed medications and experience side effects that may affect driving ability. The purpose of this study was to characterize the relationship between medications and driving safety behaviors. METHODS: Data for this study came from the five-site Longitudinal Research on Aging Drivers (LongROAD) project. Participants were active drivers, age 65-79 years at enrollment, and patients at one of the 5 participating sites. Medication names and doses were obtained at baseline based on the "brown-bag review" method. Medications were coded using the American Hospital Formulary Service system. Driving data were collected by a GPS accelerometer installed in the study participants' main vehicles. RESULTS: Medication data were available for 2949 (98.6%) of the 2990 participants, and 2898 (96.9% of all participants) had both medication data and at least 30 recorded days of driving. The median number of medications taken per study participant was seven, with a range of 0-51. Total number of medications was significantly associated with a higher rapid deceleration rate. Certain medication classes were significantly associated with other driving outcomes, including central nervous system agents (more speeding events), hormones and gastrointestinal medications (more rapid decelerations), electrolytes (fewer rapid decelerations), and antihistamines (greater right to left turn ratio). CONCLUSIONS: Older adult drivers are taking large quantities of prescription and non-prescription medications that may affect their driving safety. Certain medication classes are associated with potentially adverse driving patterns, such as speeding and rapid decelerations, while others are associated with potentially protective maneuvers, such as right hand turning. Further research is warranted to identify and mitigate potential adverse effects of such medications on driving safety in older adults.

Structural Fuzziness of the RNA-Organizing Protein SERF Determines a Toxic Gain-of-interaction.

The mechanisms by which protein complexes convert from functional to pathogenic are the subject of intensive research. Here, we report how functionally unfavorable protein interactions can be induced by structural fuzziness, i.e., by persisting conformational disorder in protein complexes. We show that extreme disorder in the bound state transforms the intrinsically disordered protein SERF1a from an RNA-organizing factor into a pathogenic enhancer of alpha-synuclein (aSyn) amyloid toxicity. We demonstrate that SERF1a promotes the incorporation of RNA into nucleoli and liquid-like artificial RNA-organelles by retaining an unusually high degree of conformational disorder in the RNA-bound state. However, this type of structural fuzziness also determines an undifferentiated interaction with aSyn. RNA and aSyn both bind to one identical, positively charged site of SERF1a by an analogous electrostatic binding mode, with similar binding affinities, and without any observable disorder-to-order transition. The absence of primary or secondary structure discriminants results in SERF1a being unable to select between nucleic acid and amyloidogenic protein, leading the pro-amyloid aSyn:SERF1a interaction to prevail in the cytosol under conditions of cellular stress. We suggest that fuzzy disorder in SERF1a complexes accounts for an adverse gain-of-interaction which favors toxic binding to aSyn at the expense of nontoxic RNA binding, thereby leading to a functionally distorted and pathogenic process. Thus, structural fuzziness constitutes a direct link between extreme conformational flexibility, amyloid aggregation, and the malfunctioning of RNA-associated cellular processes, three signatures of neurodegenerative proteinopathies.

Prevalence of Potentially Inappropriate Medication use in older drivers.

BACKGROUND: Potentially Inappropriate Medication (PIM) use has been studied in a variety of older adult populations across the world. We sought to examine the prevalence and correlates of PIM use in older drivers. METHODS: We applied the American Geriatrics Society 2015 Beers Criteria to baseline data collected from the "brown-bag" review of medications for participants of the Longitudinal Research on Aging Drivers (LongROAD) study to examine the prevalence and correlates of PIM use in a geographically diverse, community-dwelling sample of older drivers (n = 2949). Proportions of participants who used one or more PIMs according to the American Geriatrics Society 2015 Beers Criteria, and estimated odds ratios (ORs) and 95% confidence intervals (CIs) of PIM use associated with participant characteristics were calculated. RESULTS: Overall, 18.5% of the older drivers studied used one or more PIM. The most commonly used therapeutic category of PIM was benzodiazepines (accounting for 16.6% of the total PIMs identified), followed by nonbenzodiazepine hypnotics (15.2%), antidepressants (15.2%), and first-generation antihistamines (10.5%). Compared to older drivers on four or fewer medications, the adjusted ORs of PIM use were 2.43 (95% CI 1.68-3.51) for those on 5-7 medications, 4.19 (95% CI 2.95-5.93) for those on 8-11 medications, and 8.01 (95% CI 5.71-11.23) for those on ≥12 medications. Older drivers who were female, white, or living in urban areas were at significantly heightened risk of PIM use. CONCLUSION: About one in five older drivers uses PIMs. Commonly used PIMs are medications known to impair driving ability and increase crash risk. Implementation of evidence-based interventions to reduce PIM use in older drivers may confer both health and safety benefits. TRIAL REGISTRATION: Not applicable.

Increased Aggregation Tendency of Alpha-Synuclein in a Fully Disordered Protein Complex.

The recent discovery of biologically active fully disordered, so called random fuzzy protein-protein interactions leads to the question of how the high flexibility of these protein complexes correlates to aggregation and pathologic misfolding. We identify the structural mechanism by which a random fuzzy protein complex composed of the intrinsically disordered proteins alpha-Synuclein and SERF1a is able to potentiate cytotoxic aggregation. A structural model derived from an integrated NMR/SAXS analysis of the reconstituted aSyn:SERF1a complex enabled us to observe the partial deprotection of one precise aSyn amyloid nucleation element in the fully unstructured ensemble. This minimal exposure was sufficient to increase the amyloidogenic tendency of SERF1a-bound aSyn. Our findings provide a structural explanation of the previously observed pro-amyloid activity of SERF1a. They further demonstrate that random fuzziness can trigger a structurally organized disease-associated reaction such as amyloid polymerization.

Individualized Household Allergen Intervention Lowers Allergen Level But Not Asthma Medication Use: A Randomized Controlled Trial.

BACKGROUND: Environmental exposures to indoor allergens are major contributors to asthma symptoms, particularly in inner cities. The effectiveness of household allergen reduction as an adjunct to National Asthma Education Prevention Program guideline-based pharmacologic therapy in asthma has not been prospectively studied. OBJECTIVE: To study the effect of individualized allergen reduction on ability to reduce asthma pharmacologic therapy over 40 weeks. METHODS: We performed a randomized controlled trial to determine the effect of multifaceted indoor allergen avoidance measures on the ability to reduce asthma controller therapy in adults and children residing in New York City who were both sensitized and exposed to at least 1 indoor allergen. Asthma treatment and control were optimized in all subjects before randomization. RESULTS: A total of 125 subjects were randomized to receive individualized household allergen reduction and 122 received a sham intervention. Subjects in the intervention group significantly reduced all measured allergen levels (cat, dog, dust mite allergens in the bedroom, cockroach and mouse allergens in the kitchen and bedroom); those in the control group reduced only dust mite and mouse allergens in the bedroom and cockroach allergen in the kitchen. Participants in the intervention arm reduced National Asthma Education Prevention Program-based therapy from step 4.4 at randomization to 3.50 postintervention (range, 0-6); participants in the control arm reduced medication from step 4.4 to 3.4 (P = .76). There were no differences in other measured asthma outcomes. CONCLUSIONS: Targeted allergen avoidance measures do not allow for reduction in asthma pharmacologic therapy compared with usual care in patients already receiving optimal controller therapy.

TORC1 promotes phosphorylation of ribosomal protein S6 via the AGC kinase Ypk3 in Saccharomyces cerevisiae.

The target of rapamycin complex 1 (TORC1) is an evolutionarily conserved sensor of nutrient availability. Genetic and pharmacological studies in the yeast Saccharomyces cerevisiae have provided mechanistic insights on the regulation of TORC1 signaling in response to nutrients. Using a highly specific antibody that recognizes phosphorylation of the bona fide TORC1 target ribosomal protein S6 (Rps6) in yeast, we found that nutrients rapidly induce Rps6 phosphorylation in a TORC1-dependent manner. Moreover, we demonstrate that Ypk3, an AGC kinase which exhibits high homology to human S6 kinase (S6K), is required for the phosphorylation of Rps6 in vivo. Rps6 phosphorylation is completely abolished in cells lacking Ypk3 (ypk3Δ), whereas Sch9, previously reported to be the yeast ortholog of S6K, is dispensable for Rps6 phosphorylation. Phosphorylation-deficient mutations in regulatory motifs of Ypk3 abrogate Rps6 phosphorylation, and complementation of ypk3Δ cells with human S6 kinase restores Rps6 phosphorylation in a rapamycin-sensitive manner. Our findings demonstrate that Ypk3 is a critical component of the TORC1 pathway and that the use of a phospho-S6 specific antibody offers a valuable tool to identify new nutrient-dependent and rapamycin-sensitive targets in vivo.