Neuro-ophthalmic Complications in Pediatric Leukemia.

Background: Optic neuropathy in childhood leukemia occurs through multiple direct and indirect mechanisms, including leukemic infiltration of the optic nerve, infection, blood dyscrasias, or adverse effects of treatment. We aimed to characterize visual outcomes in pediatric patients with leukemia-associated neuro-ophthalmic manifestations.

Methods: We retrospectively identified patients with leukemia and optic nerve pathology over 13 years by diagnostic billing codes.

Disseminated Tuberculosis in a Healthy Adolescent Female.

Disseminated tuberculosis (TB) is an uncommon sequela of Mycobacterium TB infection in which bacteria disseminate and form colonies outside of the lungs. Most reports of disseminated TB are found in immunocompromised patients, particularly in patients with human immunodeficiency virus (HIV) infection, malnutrition, genetic susceptibility, diabetes mellitus, smoking, and alcohol abuse. Few case reports describe the finding of disseminated TB in immunocompetent patients, especially in healthy adolescents.

Postoperative Correction and Drift After Vertical Rectus Muscle Transposition for Total Sixth Cranial Nerve Palsy.

Purpose: To determine the magnitude of change between the preoperative and postoperative alignment and amount of postoperative drift for two vertical rectus muscle transpositions (VRTs).

Methods: Retrospective review of medical records of patients with total sixth cranial nerve palsy who underwent VRT procedures. The primary outcome measure was the magnitude of esotropia in prism diopters (PD) at the preoperative and postoperative visits.

Microcornea, posterior megalolenticonus, persistent fetal vasculature, chorioretinal coloboma (MPPC) syndrome: Case series post vitrectomy.

Purpose: MPPC syndrome has been described as a syndrome that presents with chorioretinal coloboma, posterior megalolenticonus, persistent fetal vasculature, and chorioretinal coloboma. The purpose of our study is to report three patients who present with a variation of MPPC syndrome who each underwent pars plana vitrectomy, pars plana lensectomy, and amblyopic management. Clinical characteristics, ancillary test findings, and post-surgical functional results are compared to what is reported in the literature.

Strabismus surgery outcomes without removal of scleral buckle in patients with previous retinal detachment repair.

Purpose: To report the motor and sensory outcomes of strabismus surgery following scleral buckle procedure for retinal detachment (RD) without removal of the scleral buckle.

Methods: The medical records of patients who underwent strabismus surgery without removal of scleral buckle following RD surgical repair at a tertiary referral center between 2002 and 2015 were reviewed retrospectively. Demographic data were recorded, and rates of surgical motor success (defined as horizontal deviation of ≤10 and vertical deviation of ≤4) and sensory success (resolution of diplopia) were calculated.

Self-assembly of MinE on the membrane underlies formation of the MinE ring to sustain function of the Escherichia coli Min system.

The pole-to-pole oscillation of the Min proteins in Escherichia coli results in the inhibition of aberrant polar division, thus facilitating placement of the division septum at the midcell. MinE of the Min system forms a ring-like structure that plays a critical role in triggering the oscillation cycle. However, the mechanism underlying the formation of the MinE ring remains unclear.

Opiates for chronic nonmalignant pain syndromes: can appropriate candidates be identified for outpatient clinic management?

Objective: To better define patients appropriate for opiate management for chronic pain syndromes.

Design: Retrospective study of 65 patients with noncancerous pain syndromes who were on or being considered for opiates and who were transitioned into a structured outpatient clinic with close monitoring and management. Noncompliance with this outpatient pain management program was the primary outcome.

The dynamic nature of the bacterial cytoskeleton.

Three of the four well-established bacterial cytoskeletal systems-the MreB, MinCDE, and FtsZ systems-undergo a variety of short-range and long-range dynamic behaviors. These include the cellular reorganization of the cytoskeletal elements, in which the proteins redistribute from a predominantly helical pole-to-pole pattern into annular structures near midcell. Despite their apparent similarity, these dramatic redistributional events in the three systems are in large part independent of each other.

Assembly of the MreB-associated cytoskeletal ring of Escherichia coli.

The Escherichia coli actin homologue MreB is part of a helical cytoskeletal structure that winds around the cell between the two poles. It has been shown that MreB redistributes during the cell cycle to form circumferential ring structures that flank the cytokinetic FtsZ ring and appear to be associated with division and segregation of the helical cytoskeleton. We show here that the MreB cytoskeletal ring also contains the MreC, MreD, Pbp2 and RodA proteins.

New insights into the cellular organization of the RNA processing and degradation machinery of Escherichia coli.

Ribonuclease E (RNase E) is a component of the Escherichia coli RNA degradosome, a multiprotein complex that also includes RNA helicase B (RhlB), polynucleotide phosphorylase (PNPase) and enolase. The degradosome plays a key role in RNA processing and degradation. The degradosomal proteins are organized as a cytoskeletal-like structure within the cell that has been thought to be associated with the cytoplasmic membrane.

RNaseE and RNA helicase B play central roles in the cytoskeletal organization of the RNA degradosome.

The RNA degradosome of Escherichia coli is a multiprotein complex that plays an essential role in normal RNA processing and decay. It was recently shown that the major degradosome constituents are organized in a coiled cytoskeletal-like structure that extends along the length of the cell. Here we show that the endoribonuclease E (RNaseE) and RNA helicase B (RhlB) components of the degradosome can each independently form coiled structures in the absence of the other degradosome proteins.

Cell shape determination in Escherichia coli.

The rigid cell wall peptidoglycan (murein) is a single giant macromolecule whose shape determines the shape of the bacterial cell. Insight into morphogenetic mechanism(s) responsible for determining the shape of the murein sacculus itself has begun to emerge only in recent years. The discovery that MfreB and Mbl are cytoskeletal actin homologues that form helical structures extending from pole to pole in rod-shaped cells has opened an exciting new field of microbial cell biology.

Duplication and segregation of the actin (MreB) cytoskeleton during the prokaryotic cell cycle.

The bacterial actin homolog MreB exists as a single-copy helical cytoskeletal structure that extends between the two poles of rod-shaped bacteria. In this study, we show that equipartition of the MreB cytoskeleton into daughter cells is accomplished by division and segregation of the helical MreB array into two equivalent structures located in opposite halves of the predivisional cell. This process ensures that each daughter cell inherits one copy of the MreB cytoskeleton.

RNaseE and the other constituents of the RNA degradosome are components of the bacterial cytoskeleton.

RNaseE is the main component of the RNA degradosome of Escherichia coli, which plays an essential role in RNA processing and decay. Localization studies showed that RNaseE and the other known degradosome components (RNA helicase B, polynucleotide phosphorylase, and enolase) are organized as helical filamentous structures that coil around the length of the cell. These resemble the helical structures formed by the MreB and MinD cytoskeletal proteins.

The bacterial cytoskeleton.

In recent years it has been shown that bacteria contain a number of cytoskeletal structures. The bacterial cytoplasmic elements include homologs of the three major types of eukaryotic cytoskeletal proteins (actin, tubulin, and intermediate filament proteins) and a fourth group, the MinD-ParA group, that appears to be unique to bacteria. The cytoskeletal structures play important roles in cell division, cell polarity, cell shape regulation, plasmid partition, and other functions.

Role of MinD-membrane association in Min protein interactions.

Division site placement in Escherichia coli involves interactions of the MinD protein with MinC and MinE and with other MinD molecules to form membrane-associated polymeric structures. In this work, as part of a study of these interactions, we established that heterologous membrane-associated proteins such as MinD can be targeted to the yeast nuclear membrane, dependent only on the presence of a membrane-binding domain and a nuclear targeting sequence. Targeting to the nuclear membrane was equally effective using the intrinsic MinD membrane-targeting domain or the completely unrelated membrane-targeting domain of cytochrome b(5).

Spatial control of bacterial division-site placement.

The site of cell division in bacterial cells is placed with high fidelity at a designated position, usually the midpoint of the cell. In normal cell division in Escherichia coli this is accomplished by the action of the Min proteins, which maintain a high concentration of a septation inhibitor near the ends of the cell, and a low concentration at midcell. This leaves the midcell site as the only available location for formation of the division septum.

The MreB and Min cytoskeletal-like systems play independent roles in prokaryotic polar differentiation.

Establishment of an axis of cell polarity and differentiation of the cell poles are fundamental aspects of cellular development in many organisms. We compared the effects of two bacterial cytoskeletal-like systems, the MreB and MinCDE systems, on these processes in Escherichia coli. We report that the Min proteins are capable of establishing an axis of oscillation that is the initial step in establishment of polarity in spherical cells, in a process that is independent of the MreB cytoskeleton.

A polymerization-depolymerization model that accurately generates the self-sustained oscillatory system involved in bacterial division site placement.

Determination of the proper site for division in Escherichia coli and other bacteria involves a unique spatial oscillatory system in which membrane-associated structures composed of the MinC, MinD and MinE proteins oscillate rapidly between the two cell poles. In vitro evidence indicates that this involves ordered cycles of assembly and disassembly of MinD polymers. We propose a mathematical model to explain this behavior.

Positioning of the MinE binding site on the MinD surface suggests a plausible mechanism for activation of the Escherichia coli MinD ATPase during division site selection.

Division site selection in Escherichia coli requires that the MinD protein interact with itself and with MinC and MinE. MinD is a member of the NifH-ArsA-Par-MinD subgroup of ATPases. The MinE-MinD interaction results in activation of MinD ATPase activity in the presence of membrane vesicles.

Mapping the MinE site involved in interaction with the MinD division site selection protein of Escherichia coli.

Interactions between the MinD and MinE proteins are required for proper placement of the Escherichia coli division septum. The site within MinE that is required for interaction with MinD was mapped by studying the effects of site-directed minE mutations on MinD-MinE interactions in yeast two-hybrid and three-hybrid experiments. This confirmed that the MinE N-terminal domain is responsible for the interaction of MinE with MinD.

Division site selection in Escherichia coli involves dynamic redistribution of Min proteins within coiled structures that extend between the two cell poles.

The MinCDE proteins of Escherichia coli are required for proper placement of the division septum at midcell. The site selection process requires the rapid oscillatory redistribution of the proteins from pole to pole. We report that the three Min proteins are organized into extended membrane-associated coiled structures that wind around the cell between the two poles.

Membrane localization of MinD is mediated by a C-terminal motif that is conserved across eubacteria, archaea, and chloroplasts.

MinD is a widely conserved ATPase that has been demonstrated to play a pivotal role in selection of the division site in eubacteria and chloroplasts. It is a member of the large ParA superfamily of ATPases that are characterized by a deviant Walker-type ATP-binding motif. MinD localizes to the cytoplasmic face of the inner membrane in Escherichia coli, and its association with the inner membrane is a prerequisite for membrane recruitment of the septation inhibitor MinC.

Division site placement in E.coli: mutations that prevent formation of the MinE ring lead to loss of the normal midcell arrest of growth of polar MinD membrane domains.

The MinE protein functions as a topological specificity factor in determining the site of septal placement in Escherichia coli. MinE assembles into a membrane-associated ring structure near midcell and directs the localization of MinD and MinC into a membrane- associated polar zone that undergoes a characteristic pole-to-pole oscillation cycle. Single (green fluorescent protein) and double label (yellow fluorescent protein/cyan fluorescent protein) fluorescence labeling experiments showed that mutational alteration of a site on the alpha-face of MinE led to a failure to assemble the MinE ring, associated with loss of the ability to support a normal pattern of division site placement.