Brolucizumab-associated intraocular inflammation in Indian patients by VRSI study group.

CONTEXT: Concerns about brolucizumab's (Pagenax®) association with intraocular inflammation (IOI) limit its use despite its cost-effectiveness and efficacy. This multicentric study analyzes IOI incidence across 21 tertiary eyecare centers in India since its introduction in October 2020. PURPOSE: To determine the real-world incidence rate of IOI in Indian patients secondary to intravitreal brolucizumab across 21 tertiary eye care centers in India. SETTINGS AND DESIGN: Retrospective multicentric, survey-based study. METHODS: Data including number of patients treated, clinical indications, side effects encountered, and IOI case details was collected via Google Forms in 21 Indian tertiary eye care centers since October 2020. Mean, median, frequency, and standard deviation were calculated for statistical analysis. RESULTS: All centers used pro re nata protocol for brolucizumab injections with a minimum injection interval of 8 weeks. The incidence of IOI was 0.79% (21 events out of 2655 eyes). Treatment indications included idiopathic polypoidal choroidal vasculopathy, neovascular age-related macular degeneration, diabetic macular edema, and off-label uses. IOI was experienced after the first injection (57%) in majority of cases with a median onset of 14 days (range: 1-65 days). IOI was mild in 28.5%, moderate in 33%, and severe in 38% of cases. Eighteen out of 21 IOI eyes recovered preinjection best corrected visual acuity or better. CONCLUSIONS: Our study found a lower IOI incidence (0.79%) with brolucizumab (Pagenax) in Indian patients compared to previously reported literature. IOI events were mostly mild to moderate, and post-treatment, most patients improved or maintained BCVA. Larger prospective multicentric studies with PRN dosing protocol are needed to confirm these findings.

Combat ocular trauma in counterinsurgency operations.

PURPOSE: To identify the pattern, distribution, and causes of ocular injuries among the security personnel participating in counterinsurgency operations (CIOps). METHODS: This was a multicentric, retrospective review of chart records of patients reporting to three hospitals located in the geographic region affected by CIOps. The hospital registry was examined for all patients diagnosed with any type of ocular trauma between January 1, 2016, and December 31, 2019. A standardized proforma was filled out using the case records, and entries were validated. RESULTS: A total of 131 ocular injuries fulfilled the criteria of the study. The mean age of the patients was 32.46 ± 10.2 years. All the patients were males. The causes of the injuries were explosive blasts in 60 eyes (45.80%), gunshot wounds in 15 eyes (11.42%), stone pelting in 16 eyes (12.21%), training-related causes in 26 eyes (29.84%), vehicular accidents in 13 eyes (9.92%), and battery blast in one eye (0.76%). Among the type of injuries, open globe injuries included 66 eyes (50.38%), closed globe injuries included 35 eyes (26.72%), isolated lid lacerations included 14 eyes (10.68%), and isolated chemical injury was seen in two eyes (1.52%). Optic nerve head avulsion was seen in two eyes (1.52%). CONCLUSION: The study revealed a considerable number of ocular injuries related to combat, with explosive bursts being the leading cause. The incidence of ocular injuries was found to be highest in zone 1. This study emphasizes the importance of the need for soldiers deployed in active CIOps regions to wear protective eyewear, such as ballistic goggles or military combat eye protection, to reduce the risk of ocular injuries.

An inadvertent usage of the deep stromal lenticule in anterior lamellar keratoplasty - An emancipator technique.

Anterior lamellar keratoplasty (ALK), of late, has gained popularity because of its prolonged graft survivability as a result of reduced endothelial cell loss. A 56-year-old female with bilateral granular corneal dystrophy was taken up for ALK in the left eye. Because of unforeseen errors during the procedure, the surgeon was obliged to customize a novel technique by using a deep stromal lenticule after removal of Descemet's membrane. Post-op visual recovery was equivalent to conventional ALK with complete epithelization of the graft. This new or adapted technique has an added advantage for surgeons to prevent forfeiture of the valuable donor tissue. In the developing world, manual dissection is still the primary technique of lamellar keratoplasty and many precious corneas get wasted because of intra-operative unintended errors of dissection and trephination. Therefore, this novel technique holds its importance in saving the precious corneal tissue, especially in developing countries, and opens a new area for exploration.

Post-corneal transplant Candida keratitis - Incidence and outcome.

PURPOSE: To report the risk factors, clinical characteristics, and outcomes of Candida keratitis following corneal transplantation in India. METHODS: On retrospective review of medical records of 789 patients, 31 eyes developed a graft infection following corneal transplantation or keratoprosthesis and we could identify the Candida infection in only five. These cases were operated at two tertiary care centers in India. These five records were reviewed for demographics, risk factors (local and systemic) for graft infection, characteristics of infective lesion, corneal scraping results, treatment plan, and the final outcome following management. RESULTS: The median age of the subjects with the Candida graft infection was 62.4 ± 10.33 years (range, 62-71 years). All patients were males. The predominant risk factors included repeat corneal transplantation (5/5), prolonged usage of topical steroids (5/5), and epithelial defects (4/5). The clinical characteristics included infiltrates of variable configuration like powdery deposits, white plaque, fluffy white infiltrate, and crystalline keratopathy. The smear showed budding yeasts in all five cases whereas culture was positive in four out of five cases. The final outcome with antifungals (systemic [4/5] and topical [5/5]) is variable. Two eyes underwent evisceration, two eyes had scar formation in the failed grafts, and one patient succumbed to the systemic disease 1-month post-corneal infection. CONCLUSION: Candida keratitis, in India, seems to be an emerging pathology following corneal transplantation and has a varied presentation. Though the outcomes following management seem to be grim, however, such infection can easily be avoided by a timely reduction of the risk factors.

Magnetoelastic coupling and spin contributions to entropy and thermal transport in biferroic yttrium orthochromite.

Direct engineering of material properties through exploitation of spin, phonon, and charge-coupled degrees of freedom is an active area of development in materials science. However, the relative contribution of the competing orders to controlling the desired behavior is challenging to decipher. In particular, the independent role of phonons, magnons, and electrons, quasiparticle coupling, and relative contributions to the phase transition free energy largely remain unexplored, especially for magnetic phase transitions. Here, we study the lattice and magnetic dynamics of biferroic yttrium orthochromite using Raman, infrared, and inelastic neutron spectroscopy techniques, supporting our experimental results with first-principles lattice dynamics and spin-wave simulations across the antiferromagnetic transition atTN∼ 138 K. Spectroscopy data and simulations together with the heat capacity (Cp) measurements, allow us to quantify individual entropic contributions from phonons (0.01 ± 0.01kBatom-1), dilational (0.03 ± 0.01kBatom-1), and magnons (0.11 ± 0.01kBatom-1) acrossTN. High-resolution phonon measurements conducted in a magnetic field show that anomalousT-dependence of phonon energies acrossTNoriginates from magnetoelastic coupling. Phonon scattering is primarily governed by the phonon-phonon coupling, with little contribution from magnon-phonon coupling, short-range spin correlations, or magnetostriction effects; a conclusion further supported by our thermal conductivity measurements conducted up to 14 T, and phenomenological modeling.

Spin-phonon coupling and thermodynamic behaviour in YCrO3and LaCrO3: inelastic neutron scattering and lattice dynamics.

We report detailed temperature-dependent inelastic neutron scattering andab initiolattice dynamics investigation of magnetic perovskites YCrO3and LaCrO3. The magnetic neutron scattering from the Cr ions exhibits significant changes with temperature and dominates at low momentum transfer regime.Ab initiocalculations performed including magnetic interactions show that the effect of magnetic interactions is very significant on the low- as well as high-energy phonon modes. We have also shown that the inelastic neutron spectrum of YCrO3mimics the magnon spectrum from a G-type antiferromagnetic system, which is consistent with previously reported magnetic structure in the compound. The pressure-dependentab initiolattice dynamics calculations are used to calculate the anisotropic thermal expansion behaviour in orthorhombic YCrO3, which is in excellent agreement with the available experimental data in the paramagnetic phase. We identify that the low energy anharmonic phonon modes involving Y vibrations contribute maximum to the thermal expansion behaviour.

Phonons and Thermal Expansion Behavior of NiSi and NiGe.

We have carried out first principles calculations of the vibrational and thermodynamic behavior in NiSi and isostructural compound NiGe. Phonon density of states has also been measured in NiSi using inelastic neutron scattering techniques. We find that the vibrational spectra of the two compounds are very different, due to the difference in the size and mass of Si and Ge. Interesting anomalous thermal behavior of NiSi due to anharmonic phonons is brought out well in our calculations, particularly the negative thermal expansion (NTE) along the b-axis of the orthorhombic unit cell. Large difference in thermal expansion behavior of NiSi and NiGe is very well reproduced by the calculations. Additionally, calculations enable to identify the phonon modes which lend major contribution to the negative thermal expansion behavior in NiSi, and reasons for negligible NTE in NiGe. Such typical representative modes at the zone-boundary along b-axis involve transverse vibrations of Si/Ge along c-axis. PACS numbers: 78.70.Nx, 63.20.-e, 65.40.-b.

To assess knowledge and attitude of parents toward children suffering from strabismus in Indian subcontinent.

PURPOSE: Strabismus and anisometropia are the most common causes of amblyopia. It can be easily prevented or treated if detected early. With the changing socio-cultural-economic milieu of the society, the perspectives of strabismus in society are gradually changing but still adequate knowledge, awareness, and attitude of parents toward strabismus will help in preventing amblyopia and aid in the proper psychosocial adaptation of such children. This study aimed to assess knowledge and attitude of parents toward children suffering from strabismus. METHODS: A prospective study was carried out from January 1 to February 29, 2016, through a structured questionnaire to assess the level of knowledge and attitude of parents of children suffering from strabismus. RESULTS: One hundred and twenty parents of children with strabismus were interviewed through a questionnaire. Education level of 78 parents was less than graduation (60%) and of 42 parents (40%) was graduation or higher. The majority of the parents, i.e., 116 (96.67%) were bothered due to strabismus. One hundred and one (84.17%) parents felt that their child's strabismus was noticed by others during interaction. Seventy-four (61.67%) parents felt that their children will have difficulty in making friends. Ninety (75%) parents felt uncomfortable if someone asked something about their child's strabismus. One hundred and ten (91.67%) parents considered strabismus as cosmetic stigma. CONCLUSION: Some parents, especially from the lower educated segment, had poor understanding of strabismus, thus resulting in late presentation and ineffective countermeasures. The key to prevent strabismic amblyopia and its psychosocial impacts is to provide health education regarding strabismus.

The CFTR trafficking mutation F508del inhibits the constitutive activity of SLC26A9.

Several members of the SLC26A family of anion transporters associate with CFTR, forming complexes in which CFTR and SLC26A functions are reciprocally regulated. These associations are thought to be facilitated by PDZ scaffolding interactions. CFTR has been shown to be positively regulated by NHERF-1, and negatively regulated by CAL in airway epithelia. However, it is unclear which PDZ-domain protein(s) interact with SLC26A9, a SLC26A family member found in airway epithelia. We have previously shown that primary, human bronchial epithelia (HBE) from non-CF donors exhibit constitutive anion secretion attributable to SLC26A9. However, constitutive anion secretion is absent in HBE from CF donors. We examined whether changes in SLC26A9 constitutive activity could be attributed to a loss of CFTR trafficking, and what role PDZ interactions played. HEK293 coexpressing SLC26A9 with the trafficking mutant F508del CFTR exhibited a significant reduction in constitutive current compared with cells coexpressing SLC26A9 and wt CFTR. We found that SLC26A9 exhibits complex glycosylation when coexpressed with F508del CFTR, but its expression at the plasma membrane is decreased. SLC26A9 interacted with both NHERF-1 and CAL, and its interaction with both significantly increased with coexpression of wt CFTR. However, coexpression with F508del CFTR only increased SLC26A9's interaction with CAL. Mutation of SLC26A9's PDZ motif decreased this association with CAL, and restored its constitutive activity. Correcting aberrant F508del CFTR trafficking in CF HBE with corrector VX-809 also restored SLC26A9 activity. We conclude that when SLC26A9 is coexpressed with F508del CFTR, its trafficking defect leads to a PDZ motif-sensitive intracellular retention of SLC26A9.

Evaluation of Physical Properties of Generic and Branded Travoprost Formulations.

PURPOSE: Comparative evaluation of pharmaceutical characteristics of three marketed generic vs branded travoprost formulations. MATERIALS AND METHODS: Three generic travoprost formulations and one branded (Travatan without benzalkonium chloride) formulation (10 vials each), obtained from authorized agents from the respective companies and having the same batch number, were used. These formulations were coded and labels were removed. At a standardized room temperature of 25°C, the drop size, pH, relative viscosity, and total drops per vial were determined for Travatan (Alcon, Fort Worth, TX, USA) and all the generic formulations. Travoprost concentration in all four brands was estimated by using liquid chromatography-coupled tandem mass spectrometry LCMS. RESULTS: Out of the four formulations, two drugs (TP 1 and TP 4) were found to follow the United States Pharmacopoeia (USP) limits for ophthalmic formulation regarding drug concentration, while the remaining two drugs failed due to the limits being either above 110% (TP 2) or below 90% (TP 3). Two of them (TP 1 and TP 2) had osmolality of 313 and 262 mOsm respectively, which did not comply with the osmolality limits within 300 mOsm (+ 10%). The pH of all the formulations ranged between 4.7 and 5.9, and the mean drop size was 30.23 ± 6.03 uL. The total amount of drug volume in the bottles varied from 2.58 ± 0.15 to 3.38 ± 0.06 mL/bottle. CONCLUSION: There are wide variations in the physical properties of generic formulations available in India. Although some generic drugs are compliant with the pharmacopeia standards, this study underscores the need for a better quality control in the production of generic travoprost formulations. How to cite this article: Wadhwani M, Mishra SK, Angmo D, Velpandian T, Sihota R, Kotnala A, Bhartiya S, Dada T. Evaluation of Physical Properties of Generic and Branded Travoprost Formulations. J Curr Glaucoma Pract. 2016;10(2):49-55.

New insights into the compressibility and high-pressure stability of Ni(CN)2: a combined study of neutron diffraction, Raman spectroscopy, and inelastic neutron scattering.

Nickel cyanide is a layered material showing markedly anisotropic behaviour. High-pressure neutron diffraction measurements show that at pressures up to 20.1 kbar, compressibility is much higher in the direction perpendicular to the layers, c, than in the plane of the strongly chemically bonded metal-cyanide sheets. Detailed examination of the behaviour of the tetragonal lattice parameters, a and c, as a function of pressure reveal regions in which large changes in slope occur, for example, in c(P) at 1 kbar. The experimental pressure dependence of the volume data is fitted to a bulk modulus, B0, of 1050 (20) kbar over the pressure range 0-1 kbar, and to 124 (2) kbar over the range 1-20.1 kbar. Raman spectroscopy measurements yield additional information on how the structure and bonding in the Ni(CN)2 layers change with pressure and show that a phase change occurs at about 1 kbar. The new high-pressure phase, (Phase PII), has ordered cyanide groups with sheets of D4h symmetry containing Ni(CN)4 and Ni(NC)4 groups. The Raman spectrum of phase PII closely resembles that of the related layered compound, Cu1/2Ni1/2(CN)2, which has previously been shown to contain ordered C≡N groups. The phase change, PI to PII, is also observed in inelastic neutron scattering studies which show significant changes occurring in the phonon spectra as the pressure is raised from 0.3 to 1.5 kbar. These changes reflect the large reduction in the interlayer spacing which occurs as Phase PI transforms to Phase PII and the consequent increase in difficulty for out-of-plane atomic motions. Unlike other cyanide materials e.g. Zn(CN)2 and Ag3Co(CN)6, which show an amorphization and/or a decomposition at much lower pressures (~100 kbar), Ni(CN)2 can be recovered after pressurising to 200 kbar, albeit in a more ordered form.

Scanning laser polarimetry in glaucoma.

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

Comparative evaluation of time domain and spectral domain optical coherence tomography in retinal nerve fiber layer thickness measurements.

INTRODUCTION: Before any new device can replace another for use in clinical practice, it is imperative that its reproducibility, diagnostic accuracy, and ability to detect changes over time are tested. OBJECTIVE: To evaluate retinal nerve fiber layer (RNFL) measurements between two optical coherence tomography (OCT) systems: the Stratus OCT, a time domain system, and the Cirrus HD-OCT, a spectral domain system (both by Carl Zeiss Meditec, Inc., Dublin, CA). MATERIALS AND METHODS: An observational cross-sectional study was carried out involving 20 eyes with primary open angle glaucoma and 32 eyes of healthy controls. One eye of each patient was imaged on the same day with each instrument. The RNFL thicknesses measured by the two instruments were compared. MAIN OUTCOME MEASURES: Each clock hour, quadrant, and average RNFL thickness was determined on each of the two instruments. STATISTICS: The reliability was assessed by the intra-class correlation coefficient (ICC) and the Bland Altman plot for the limits of agreement for the overall mean RNFL thickness and for each quadrant. RESULTS: A randomly selected eye of each of the 52 participants was analyzed. The mean temporal, superior, nasal and inferior RNFL thickness (in microns) were found to be 65.42±18.98, 114.85±26.67, 75.83±28.61 and 116.35±29.43 when measured by the Stratus OCT. In glaucoma patients these values were 55.06±18.22, 97.86±29.37, 63.44±24.89, and 102.94±38.20; and in controls these values were 70.59±17.40, 123.61±20.65, 82.03±28.67 and 123.06±21.63 respectively. The mean temporal, superior, nasal and inferior RNFL thickness (in microns) were 62.00±13.08, 112.00±25.13, 68.56±16.66 and 114.23±25.82 respectively, when measured with the Cirrus OCT. In glaucoma patients these values were 57.88±12.99, 98.56±26.88, 64.63±12.52 and 105.50±29.49; while in the control group these were 64.06±12.82, 118.72±21.63, 70.53±18.33, and 118.59±23.05 respectively. Intraclass correlation coefficient alpha (ICC alpha) for the temporal, superior, nasal and inferior quadrant RNFL thickness measurements were 0.81, 0.85, 0.66 and 0.93 respectively. Bland-Altman plots showed the limits of agreement (95%CI) for average RNFL to be 4.59±20.10 in the control group. In patients of glaucoma, Bland-Altman plots showed the limits of agreement (95%CI) for average RNFL to be 1.56±21.50. CONCLUSIONS: There is considerable variability in the RNFL thickness measurements made by the Cirrus and Stratus OCT that exceeds the limits of resolution afforded by the instruments. RNFL measurements obtained from the two OCT systems may not be used interchangeably.

High-affinity Dkk1 receptor Kremen1 is internalized by clathrin-mediated endocytosis.

Kremens are high-affinity receptors for Dickkopf 1 (Dkk1) and regulate the Wnt/ß-catenin signaling pathway by down-regulating the low-density lipoprotein receptor-related protein 6 (LRP6). Dkk1 competes with Wnt for binding to LRP6; binding of Dkk1 inhibits canonical signaling through formation of a ternary complex with Kremen. The majority of down-regulated clathrin-mediated endocytic receptors contain short conserved regions that recognize tyrosine or dileucine sorting motifs. In this study, we found that Kremen1 is internalized from the cell surface in a clathrin-dependent manner. Kremen1 contains an atypical dileucine motif with the sequence DXXXLV. Mutation of LV to AA in this motif blocked Kremen1 internalization; as reported previously for other proteins, the aspartic acid residue in Kremen1 is not critical. Inhibition of expression of the adaptor protein 2 (AP-2) or inhibition of clathrin by pitstop 2 also blocked Kremen1 internalization. The novel amino acid sequence identified in Kremen1 is similar to the motif previously identified in hydra, yeast, and other organisms known to signal from the trans-Golgi network to the endosomal compartment.

Evaluating eye drop instillation technique in glaucoma patients.

AIM: To evaluate the technique of eye drop instillation in glaucoma patients. METHODS: Seventy patients with primary open-angle glaucoma or primary angle-closure glaucoma, self-administering topical antiglaucoma medications for at least 6 months were evaluated. All patients instilled a tear substitute in 1 eye using the same technique they used for instilling antiglaucoma medications at home. The parameters that were recorded included time taken to instill the first drop, number of eye drops instilled, drop contact location, any contact with the tip of the bottle, and closure of the eyelids or tear duct after drop instillation. RESULTS: The mean age of the patients was 54.1±10.0 years. The mean time taken to instill the first drop was 14.8±3.7 seconds (range, 8.7 to 23.5 s). The mean number of drops squeezed from the bottle per instillation was 1.8±1.2 drops (range, 1 to 8 drops). In 22 patients (31.43%), the eye drops fell on the eyelids or cheek. Fifty-three patients (75.7%) touched the tip of the bottle to the globe or periocular tissue. Twenty patients (28.57%) closed eyes after instilling drops and 4 patients (5.7%) occluded the punctum. Only 6 patients (8.57%) were able to correctly instill the eye drops (squeeze out 1 drop and instill it into the conjunctival sac without bottle tip contact). CONCLUSIONS: Nearly, 9 of 10 glaucoma patients were unable to instill eye drops correctly. This may be an important cause of unintentional noncompliance in glaucoma medical therapy.

Differential modal Zernike wavefront sensor employing a computer-generated hologram: a proposal.

The process of Zernike mode detection with a Shack-Hartmann wavefront sensor is computationally extensive. A holographic modal wavefront sensor has therefore evolved to process the data optically by use of the concept of equal and opposite phase bias. Recently, a multiplexed computer-generated hologram (CGH) technique was developed in which the output is in the form of bright dots that specify the presence and strength of a specific Zernike mode. We propose a wavefront sensor using the concept of phase biasing in the latter technique such that the output is a pair of bright dots for each mode to be sensed. A normalized difference signal between the intensities of the two dots is proportional to the amplitude of the sensed Zernike mode. In our method the number of holograms to be multiplexed is decreased, thereby reducing the modal cross talk significantly. We validated the proposed method through simulation studies for several cases. The simulation results demonstrate simultaneous wavefront detection of lower-order Zernike modes with a resolution better than lambda/50 for the wide measurement range of +/-3.5lambda with much reduced cross talk at high speed.

The efficacy of Ahmed glaucoma valve drainage devices in cases of adult refractory glaucoma in Indian eyes.

AIM: To evaluate the efficacy of Ahmed glaucoma valve (AGV) drainage devices in cases of adult refractory glaucoma in Indian eyes. SETTINGS AND DESIGN: Retrospective interventional case series study. MATERIALS AND METHODS: Fifty two eyes of 32 patients of refractory glaucoma in the age group of 35 to 60 years who underwent AGV implantation with or without concomitant procedures from January 2003 to Jan 2007 were studied. Of these, 46 eyes (88%) had undergone filtering surgery earlier whereas remaining eyes underwent primary AGV implantation following failure of maximal medical therapy. The follow up ranged between 12 months to 48 months RESULTS: Eighteen eyes (35%) had undergone phacoemulsification with AGV implantation, penetrating keratoplasty (PK) with AGV and intraocular lens (IOL) implantation in 13 eyes (25%), AGV over preexisting IOL in eight eyes (15%). AGV implantation alone was done in six (11%) eyes. Anterior chamber (AC) reconstruction with secondary IOL and AGV was performed in the remaining eyes. The mean intra ocular pressure (IOP) decreased from 36.3 +/- 15.7 mm Hg to 19.6 +/- 9.2 mm Hg. Complete success as per criteria was achieved in 46 eyes (88%). None of the eyes had failure to maintain IOP control following AGV. CONCLUSION: The AGV resulted in effective and sustained control of IOP in cases of adult refractory glaucoma in intermediate follow up.

Syp1 is a conserved endocytic adaptor that contains domains involved in cargo selection and membrane tubulation.

Internalization of diverse transmembrane cargos from the plasma membrane requires a similarly diverse array of specialized adaptors, yet only a few adaptors have been characterized. We report the identification of the muniscin family of endocytic adaptors that is conserved from yeast to human beings. Solving the structures of yeast muniscin domains confirmed the unique combination of an N-terminal domain homologous to the crescent-shaped membrane-tubulating EFC/F-BAR domains and a C-terminal domain homologous to cargo-binding mu homology domains (muHDs). In vitro and in vivo assays confirmed membrane-tubulation activity for muniscin EFC/F-BAR domains. The muHD domain has conserved interactions with the endocytic adaptor/scaffold Ede1/eps15, which influences muniscin localization. The transmembrane protein Mid2, earlier implicated in polarized Rho1 signalling, was identified as a cargo of the yeast adaptor protein. These and other data suggest a model in which the muniscins provide a combined adaptor/membrane-tubulation activity that is important for regulating endocytosis.

Clathrin regulates the association of PIPKIgamma661 with the AP-2 adaptor beta2 appendage.

The AP-2 clathrin adaptor differs fundamentally from the related AP-1, AP-3, and AP-4 sorting complexes because membrane deposition does not depend directly on an Arf family GTPase. Instead phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) appears to act as the principal compartmental cue for AP-2 placement at the plasma membrane as well as for the docking of numerous other important clathrin coat components at the nascent bud site. This PtdIns(4,5)P(2) dependence makes type I phosphatidylinositol 4-phosphate 5-kinases (PIPKIs) lynchpin enzymes in the assembly of clathrin-coated structures at the cell surface. PIPKIgamma is the chief 5-kinase at nerve terminals, and here we show that the 26-amino acid, alternatively spliced C terminus of PIPKIgamma661 is an intrinsically unstructured polypeptide that binds directly to the sandwich subdomain of the AP-2 beta2 subunit appendage. An aromatic side chain-based, extended interaction motif that also includes the two bulky C-terminal residues of the short PIPKIgamma635 variant is necessary for beta2 appendage engagement. The clathrin heavy chain accesses the same contact surface on the AP-2 beta2 appendage, but because of additional clathrin binding sites located within the unstructured hinge segment of the beta2 subunit, clathrin binds the beta2 chain with a higher apparent affinity than PIPKIgamma661. A clathrin-regulated interaction with AP-2 could allow PIPKIgamma661 to be strategically positioned for regional PtdIns(4,5)P(2) generation during clathrin-coated vesicle assembly at the synapse.