A novel class of self-complementary AAV vectors with multiple advantages based on cceAAV lacking mutant ITR

Self-complementary AAV vectors (scAAV) use a mutant inverted terminal repeat (mITR) for efficient packaging of complementary stranded DNA, enabling rapid transgene expression. However, inefficient resolution at the mITR leads to the packaging of monomeric or subgenomic AAV genomes. These noncanonical particles reduce transgene expression and may affect the safety of gene transfer. To address these issues, we have developed a novel class of scAAV vectors called covalently closed-end double-stranded AAV (cceAAV) that eliminate the mITR resolution step during production. Instead of using a mutant ITR, we used a 56-bp recognition sequence of protelomerase (TelN) to covalently join the top and bottom strands, allowing the vector to be generated with just a single ITR. To produce cceAAV vectors, the vector plasmid is initially digested with TelN, purified, and then subjected to a standard triple-plasmid transfection protocol followed by traditional AAV vector purification procedures. Such cceAAV vectors demonstrate yields comparable to scAAV vectors. Notably, we observed enhanced transgene expression as compared to traditional scAAV vectors. The treatment of mice with hemophilia B with cceAAV-FIX resulted in significantly enhanced long-term FIX expression. The cceAAV vectors hold several advantages over scAAV vectors, potentially leading to the development of improved human gene therapy drugs.

B cell focused transient immune suppression protocol for efficient AAV readministration to the liver

Adeno-associated virus (AAV) vectors are used for correcting multiple genetic disorders. Although the goal is to achieve lifelong correction with a single vector administration, the ability to redose would enable the extension of therapy in cases in which initial gene transfer is insufficient to achieve a lasting cure, episomal vector forms are lost in growing organs of pediatric patients, or transgene expression is diminished over time. However, AAV typically induces potent and long-lasting neutralizing antibodies (NAbs) against capsid that prevents re-administration. To prevent NAb formation in hepatic AAV8 gene transfer, we developed a transient B cell-targeting protocol using a combination of monoclonal Ab therapy against CD20 (for B cell depletion) and BAFF (to slow B cell repopulation). Initiation of immunosuppression before (rather than at the time of) vector administration and prolonged anti-BAFF treatment prevented immune responses against the transgene product and abrogated prolonged IgM formation. As a result, vector re-administration after immune reconstitution was highly effective. Interestingly, re-administration before the immune system had fully recovered achieved further elevated levels of transgene expression. Finally, this immunosuppression protocol reduced Ig-mediated AAV uptake by immune cell types with implications to reduce the risk of immunotoxicities in human gene therapy with AAV.

TLR9-independent CD8+ T cell responses in hepatic AAV gene transfer through IL-1R1-MyD88 signaling

Upon viral infection of the liver, CD8+ T cell responses may be triggered despite the immune suppressive properties that manifest in this organ. We sought to identify pathways that activate responses to a neoantigen expressed in hepatocytes, using adeno-associated viral (AAV) gene transfer. It was previously established that cooperation between plasmacytoid dendritic cells (pDCs), which sense AAV genomes by Toll-like receptor 9 (TLR9), and conventional DCs promotes cross-priming of capsid-specific CD8+ T cells. Surprisingly, we find local initiation of a CD8+ T cell response against antigen expressed in ∼20% of murine hepatocytes, independent of TLR9 or type I interferons and instead relying on IL-1 receptor 1-MyD88 signaling. Both IL-1α and IL-1β contribute to this response, which can be blunted by IL-1 blockade. Upon AAV administration, IL-1-producing pDCs infiltrate the liver and co-cluster with XCR1+ DCs, CD8+ T cells, and Kupffer cells. Analogous events were observed following coagulation factor VIII gene transfer in hemophilia A mice. Therefore, pDCs have alternative means of promoting anti-viral T cell responses and participate in intrahepatic immune cell networks similar to those that form in lymphoid organs. Combined TLR9 and IL-1 blockade may broadly prevent CD8+ T responses against AAV capsid and transgene product.

Comprehensive Comparison of AAV Purification Methods: Iodixanol Gradient Centrifugation vs. Immuno-Affinity Chromatography

Recombinant adeno-associated viruses (AAVs) have emerged as a widely used gene delivery platform for both basic research and human gene therapy. To ensure and improve the safety profile of AAV vectors, substantial efforts have been dedicated to the vector production process development using suspension HEK293 cells. Here, we studied and compared two downstream purification methods, iodixanol gradient ultracentrifugation versus immuno-affinity chromatography (POROS™ CaptureSelect™ AAVX column). We tested multiple vector batches that were separately produced (including AAV5, AAV8, and AAV9 serotypes). To account for batch-to-batch variability, each batch was halved for subsequent purification by either iodixanol gradient centrifugation or affinity chromatography. In parallel, purified vectors were characterized, and transduction was compared both in vitro and in vivo in mice (using multiple transgenes: Gaussia luciferase, eGFP, and human factor IX). Each purification method was found to have its own advantages and disadvantages regarding purity, viral genome (vg) recovery, and relative empty particle content. Differences in transduction efficiency were found to reflect batch-to-batch variability rather than disparities between the two purification methods, which were similarly capable of yielding potent AAV vectors.

Breaking membrane barriers to neutralize E. coli and K. pneumoniae virulence with PEGylated branched polyethylenimine

Bacterial infections caused by Gram-negative pathogens, such as those in the family Enterobacteriaceae, are among the most difficult to treat because effective therapeutic options are either very limited or non-existent. This raises serious concern regarding the emergence and spread of multi-drug resistant (MDR) pathogens in the community setting; and thus, creates the need for discovery efforts and/or early-stage development of novel therapies for infections. Our work is directed towards branched polyethylenimine (BPEI) modified with polyethylene glycol (PEG) as a strategy for targeting virulence from Gram-negative bacterial pathogens. Here, we neutralize lipopolysaccharide (LPS) as a barrier to the influx of antibiotics. Data demonstrate that the β-lactam antibiotic oxacillin, generally regarded as ineffective against Gram-negative bacteria, can be potentiated by 600 Da BPEI to kill some Escherichia coli and some Klebsiella pneumoniae. Modification of 600 Da BPEI with polyethylene glycol (PEG) could increase drug safety and improves potentiation activity. The ability to use the Gram-positive agent, oxacillin, against Gram-negative pathogens could expand the capability to deliver effective treatments that simplify, reduce, or eliminate some complicated treatment regimens.

β Cell microRNAs Function as Molecular Hubs of Type 1 Diabetes Pathogenesis and as Biomarkers of Diabetes Risk

MicroRNAs (miRNAs) are small non-coding RNAs that play a crucial role in modulating gene expression and are enriched in cell-derived extracellular vesicles (EVs). We investigated whether miRNAs from human islets and islet-derived EVs could provide insight into β cell stress pathways activated during type 1 diabetes (T1D) evolution, therefore serving as potential disease biomarkers. We treated human islets from 10 cadaveric donors with IL-1β and IFN-γ to model T1D ex vivo. MicroRNAs were isolated from islets and islet-derived EVs, and small RNA sequencing was performed. We found 20 and 14 differentially expressed (DE) miRNAs in cytokine- versus control-treated islets and EVs, respectively. Interestingly, the miRNAs found in EVs were mostly different from those found in islets. Only two miRNAs, miR-155-5p and miR-146a-5p, were upregulated in both islets and EVs, suggesting selective sorting of miRNAs into EVs. We used machine learning algorithms to rank DE EV-associated miRNAs, and developed custom label-free Localized Surface Plasmon Resonance-based biosensors to measure top ranked EVs in human plasma. Results from this analysis revealed that miR-155, miR-146, miR-30c, and miR-802 were upregulated and miR-124-3p was downregulated in plasma-derived EVs from children with recent-onset T1D. In addition, miR-146 and miR-30c were upregulated in plasma-derived EVs of autoantibody positive (AAb+) children compared to matched non-diabetic controls, while miR-124 was downregulated in both T1D and AAb+ groups. Furthermore, single-molecule fluorescence in situ hybridization confirmed increased expression of the most highly upregulated islet miRNA, miR-155, in pancreatic sections from organ donors with AAb+ and T1D.

Chemical modification of AAV9 capsid with N-ethyl maleimide alters vector tissue tropism

Although more adeno-associated virus AAV-based drugs enter the clinic, vector tissue tropism remains an unresolved challenge that limits its full potential despite that the tissue tropism of naturally occurring AAV serotypes can be altered by genetic engineering capsid vie DNA shuffling, or molecular evolution. To further expand the tropism and thus potential applications of AAV vectors, we utilized an alternative approach that employs chemical modifications to covalently link small molecules to reactive exposed Lysine residues of AAV capsids. We demonstrated that AAV9 capsid modified with N-ethyl Maleimide (NEM) increased its tropism more towards murine bone marrow (osteoblast lineage) while decreased transduction of liver tissue compared to the unmodified capsid. In the bone marrow, AAV9-NEM transduced Cd31, Cd34, and Cd90 expressing cells at a higher percentage than unmodified AAV9. Moreover, AAV9-NEM localized strongly in vivo to cells lining the calcified trabecular bone and transduced primary murine osteoblasts in culture, while WT AAV9 transduced undifferentiated bone marrow stromal cells as well as osteoblasts. Our approach could provide a promising platform for expanding clinical AAV development to treat bone pathologies such as cancer and osteoporosis. Thus, chemical engineering the AAV capsid holds great potential for development of future generations of AAV vectors.

Dimerization of 600 Da branched polyethylenimine improves β-lactam antibiotic potentiation against antibiotic-resistant Staphylococcus epidermidis and Pseudomonas aeruginosa

Antibiotic resistance is a growing concern in the medical field. Drug-susceptible infections are often treated with β-lactam antibiotics, which bind to enzymes known as penicillin-binding proteins (PBPs). When the PBPs are disabled, the integrity of the cell wall is compromised, leading to cell lysis. Resistance renders β-lactam antibiotics ineffective, and clinicians turn to be more effective, but often more toxic, antibiotics. An alternative approach is combining antibiotics with compounds that disable resistance mechanisms. Previously, we have shown that low-molecular-weight 600 Da branched polyethylenimine restores β-lactam susceptibility to Gram-positive and Gram-negative pathogens with antibiotic resistance. In this study, this approach is extended to the homodimers of 600 Da BPEI that have improved potentiation properties compared to monomers of 600 Da BPEI and 1200 Da BPEI. The homodimers are synthesized by linking two 600 Da BPEI molecules with methylenebisacrylamide (MBAA). The resulting product was characterized with FTIR spectroscopy, ¹ H NMR spectroscopy, checkerboard microbroth dilution assays, and cell toxicity assays. These data show that the 600 Da BPEI homodimer is more effective than 1200 Da BPEI toward the potentiation of oxacillin against methicillin-resistant Staphylococcus epidermidis and the potentiation of piperacillin against Pseudomonas aeruginosa.

Cryptic resolution sites in the vector plasmid lead to the heterogeneities in the rAAV vectors

Recombinant adeno-associated virus (rAAV) vectors carry a cassette of interest retaining only the inverted terminal repeats (ITRs) from the wild-type virus. Conventional rAAV production primarily uses a vector plasmid as well as helper genes essential for AAV replication and packaging. Nevertheless, plasmid backbone related contaminants have been a major source of vector heterogeneity. The mechanism driving the contamination phenomenon has yet to be elucidated. Here we identified cryptic resolution sites in the plasmid backbone as a key source for producing snapback genomes, which leads to the increase of vector genome heterogeneity in encapsidated virions. By using a single ITR plasmid as a model molecule and mapping subgenomic particles, we found that there exist a few typical DNA break hotspots in the vector DNA plasmid backbone, for example, on the ampicillin DNA element, called aberrant rescue sites. DNA around these specific breakage sites may assume some typical secondary structures. Similar to normal AAV vectors, plasmid DNA with a single ITR was able to rescue and replicate efficiently. These subgenomic DNA species significantly compete for trans factors required for rAAV rescue, replication, and packaging. The replication of single ITR contaminants during AAV production is independent of size. Packaging of these species is greatly affected by its size. A single ITR and a cryptic resolution site in the plasmid work synergistically, likely causing a source of plasmid backbone contamination.

Subgenomic particles in rAAV vectors result from DNA lesion/break and non-homologous end joining of vector genomes

Recombinant adeno-associated virus (rAAV) vectors have been developed for therapeutic treatment of genetic diseases. Current rAAV vectors administered to affected individuals often contain vector DNA-related contaminants. Here we present a thorough molecular analysis of the configuration of non-standard AAV genomes generated during rAAV production using single-molecule sequencing. In addition to the sub-vector genomic-size particles containing incomplete AAV genomes, our results showed that rAAV preparations were contaminated with multiple categories of subgenomic particles with a snapback genome (SBG) configuration or a vector genome with deletions. Through CRISPR and nuclease-based modeling in tissue culture cells, we identified that a potential mechanism leading to formation of non-canonical genome particles occurred through non-homologous end joining of fragmented vector genomes caused by genome lesions or DNA breaks present in the host cells. The results of this study advance our understanding of AAV vectors and provide new clues for improving vector efficiency and safety profiles for use in human gene therapy.

Fast & High Throughput LC-MS Characterization, and Peptide Mapping of Engineered AAV Capsids Using LC-MS/MS

Adeno-associated virus (AAV) has emerged as a leading platform for gene therapy. With the skyrocketing rate of AAV research and the prevalence of many new engineered capsids being investigated in preclinical and clinical trials, capsid characterization plays a vital role in serotype confirmation and quality control. Further, peptide mapping the capsid proteins might inevitably be a future requirement by regulatory agencies since it is a critical step in good manufacturing practice (GMP) for biotherapeutic characterization. To overcome many challenges that traditional methods like SDS-PAGE and western blots carry, liquid chromatography and mass spectrometry (LC-MS) allows high resolution and sensitivity with great accuracy in characterizing the AAV capsid proteins. Our optimized LC-MS method provides quick sample preparation, a fast and high-throughput 4-min run, and high sensitivity, which allows for very efficient characterization of wild-type and engineered capsids. This study also reports the usage of LC-MS/MS peptide mapping of AAV capsid proteins to determine the most accessible lysine residues targeted by chemical modifications. Our detailed protocols are anticipated to promote the development and discovery of AAV variants with high accuracy and efficiency.

Genomic Designs of rAAVs Contribute to Pathological Changes in the Livers and Spleens of Mice

Recombinant AAV (rAAV) gene therapy is being investigated as an effective therapy for several diseases including hemophilia B. Reports of liver tumor development in certain mouse models due to AAV treatment and genomic integration of the rAAV vector has raised concerns about the long-term safety and efficacy of this gene therapy. To investigate whether rAAV treatment causes cancer, we utilized two mouse models, inbred C57BL/6 and hemophilia B Balb/C mice (HemB), to test if injecting a high dose of various rAAV8 vectors containing or lacking hFIX transgene, a Poly-A sequence, or the CB or TTR promoter triggered liver fibrosis and/or cancer development over the course of the 6.5-month study. We observed no liver tumors in either mouse cohort regardless of rAAV treatment through ultrasound imaging, gross anatomical assessment at sacrifice, and histology. We did, however, detect differences in collagen deposition in C57BL/6 livers and HemB spleens of rAAV-injected mice. Pathology reports of the HemB mice revealed many pathological phenomena, including fibrosis and inflammation in the livers and spleens across different AAV-injected HemB mice. Mice from both cohorts injected with the TTR-hFIX vector demonstrated minimal adverse events. While not tumorigenic, high dose of rAAVs, especially those with incomplete genomes, can influence liver and spleen health negatively that could be problematic for cementing AAVs as a broad therapeutic option in the clinic.

Chemical Modifications of the Capsid for Redirecting and Improving the Efficacy of Adeno-Associated Virus Vectors

Adeno-associated virus (AAV) vector-directed gene therapy is one of the most exciting modalities of biotechnology as more applications enter clinical stage. Although AAV vectors generally feature low toxicity, high stability, and long-lasting transgene expression, potential challenging issues of AAV include high vector dose, limited tissue tropism, and the host immune response and inflammation, which are all related to the capsid protein. To overcome these challenges, various strategies have been developed to engineer AAV capsids. Apart from widely employed genetic engineering of capsid protein, powerful and versatile chemical modification strategies are underexploited. This minireview summarizes recent advances and our perspectives for future direction in AAV capsid chemical modification to enhance its therapeutic use for gene therapy.

Dual-Function Potentiation by PEG-BPEI Restores Activity of Carbapenems and Penicillins against Carbapenem-Resistant Enterobacteriaceae

The rise of life-threatening carbapenem-resistant Enterobacteriaceae (CRE) infections has become a critical medical threat. Some of the most dangerous CRE bacteria can produce enzymes that degrade a wide range of antibiotics, including carbapenems and β-lactams. Infections by CRE have a high mortality rate, and survivors can have severe morbidity from treatment with toxic last-resort antibiotics. CRE have mobile genetic elements that transfer resistance genes to other species. These bacteria also circulate throughout the healthcare system. The mobility and spread of CRE need to be curtailed, but these goals are impeded by having few agents that target a limited range of pathogenic CRE species. Against CRE possessing the metallo-β-lactamase NDM-1, Klebsiella pneumoniae ATCC BAA-2146 and Escherichia coli ATCC BAA-2452, the potentiation of meropenem and imipenem is possible with low-molecular weight branched polyethylenimine (600 Da BPEI) and its poly(ethylene glycol) (PEG)ylated derivative (PEG-BPEI) that has a low in vivo toxicity. The mechanism of action is elucidated with fluorescence assays of drug influx and isothermal calorimetry data showing the chelation of essential Zn2+ ions. These results suggested that 600 Da BPEI and PEG-BPEI may also improve the uptake of antibiotics and β-lactamase inhibitors. Indeed, the CRE E. coli strain is rendered susceptible to the combination of piperacillin and tazobactam. These results expand the possible utility of 600 Da BPEI potentiators, where previously we have demonstrated the ability to improve antibiotic efficacy against antibiotic resistant clinical isolates of Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis.

PEGylation of Polyethylenimine Lowers Acute Toxicity while Retaining Anti-Biofilm and β-Lactam Potentiation Properties against Antibiotic-Resistant Pathogens

Bacterial biofilms, often impenetrable to antibiotic medications, are a leading cause of poor wound healing. The prognosis is worse for wounds with biofilms of antimicrobial-resistant (AMR) bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), and multi-drug resistant Pseudomonas aeruginosa (MDR-PA). Resistance hinders initial treatment of standard-of-care antibiotics. The persistence of MRSA, MRSE, and/or MDR-PA often allows acute infections to become chronic wound infections. The water-soluble hydrophilic properties of low-molecular-weight (600 Da) branched polyethylenimine (600 Da BPEI) enable easy drug delivery to directly attack AMR and biofilms in the wound environment as a topical agent for wound treatment. To mitigate toxicity issues, we have modified 600 Da BPEI with polyethylene glycol (PEG) in a straightforward one-step reaction. The PEG-BPEI molecules disable β-lactam resistance in MRSA, MRSE, and MDR-PA while also having the ability to dissolve established biofilms. PEG-BPEI accomplishes these tasks independently, resulting in a multifunction potentiation agent. We envision wound treatment with antibiotics given topically, orally, or intravenously in which external application of PEG-BPEIs disables biofilms and resistance mechanisms. In the absence of a robust pipeline of new drugs, existing drugs and regimens must be re-evaluated as combination(s) with potentiators. The PEGylation of 600 Da BPEI provides new opportunities to meet this goal with a single compound whose multifunction properties are retained while lowering acute toxicity.

Expanding the Spectrum of Antibiotics Capable of Killing Multidrug-Resistant Staphylococcus aureus and Pseudomonas aeruginosa

Infections from antibiotic-resistant Staphylococcus aureus and Pseudomonas aeruginosa are a serious threat because reduced antibiotic efficacy complicates treatment decisions and prolongs the disease state in many patients. To expand the arsenal of treatments against antimicrobial-resistant (AMR) pathogens, 600-Da branched polyethylenimine (BPEI) can overcome antibiotic resistance mechanisms and potentiate β-lactam antibiotics against Gram-positive bacteria. BPEI binds cell-wall teichoic acids and disables resistance factors from penicillin binding proteins PBP2a and PBP4. This study describes a new mechanism of action for BPEI potentiation of antibiotics generally regarded as agents effective against Gram-positive pathogens but not Gram-negative bacteria. 600-Da BPEI is able to reduce the barriers to drug influx and facilitate the uptake of a non-β-lactam co-drug, erythromycin, which targets the intracellular machinery. Also, BPEI can suppress production of the cytokine interleukin IL-8 by human epithelial keratinocytes. This enables BPEI to function as a broad-spectrum antibiotic potentiator, and expands the opportunities to improve drug design, antibiotic development, and therapeutic approaches against pathogenic bacteria, especially for wound care.

Overcoming Multidrug Resistance and Biofilms of Pseudomonas aeruginosa with a Single Dual-Function Potentiator of β-Lactams

Clinicians prescribe hundreds of millions of β-lactam antibiotics to treat the majority of patients presenting with bacterial infections. Patient outcomes are positive unless resistant bacteria, such as Pseudomonas aeruginosa (P. aeruginosa), are present. P. aeruginosa has both intrinsic and acquired antibiotic resistance, making clinical management of infection a real challenge, particularly when these bacteria are sequestered in biofilms. These problems would be alleviated if, upon the initial presentation of bacterial infection symptoms, clinicians were able to administer an antibiotic that kills both susceptible and otherwise resistant bacteria and eradicates biofilms. As the most common class of antibiotics, β-lactams could be used in a new drug if the leading causes of β-lactam antibiotic resistance, permeation barriers from lipopolysaccharide, efflux pumps, and β-lactamase enzymes, were also defeated. Against P. aeruginosa and their biofilms, the potency of β-lactam antibiotics is restored with 600 Da branched polyethylenimine (600 Da BPEI). Checkerboard assays using microtiter plates demonstrate the potentiation of piperacillin, cefepime, Meropenem, and erythromycin antibiotics. Growth curves demonstrate that only a combination of 600 Da BPEI and piperacillin produces growth inhibition against antibiotic resistant P. aeruginosa. Scanning electron microscopy (SEM) was used to confirm that the combination treatment leads to abnormal P. aeruginosa morphology. Data collected with isothermal titration calorimetry and fluorescence spectroscopy demonstrate a mechanism of action in which potentiation at low concentrations of 600 Da BPEI reduces diffusion barriers from lipopolysaccharides without disrupting the outer membrane itself. Coupled with the ability to overcome a reduction in antibiotic activity created by biofilm exopolymers, targeting anionic sites on lipopolysaccharides and biofilm exopolysaccharides with the same compound provides new opportunities to counter the rise of multidrug-resistant infections.

Low-Molecular-Weight Branched Polyethylenimine Potentiates Ampicillin against MRSA Biofilms

Methicillin-resistant Staphylococcus aureus (MRSA) infections pose a serious threat worldwide. MRSA is the predominant species isolated from medical-device-related biofilm infections and chronic wounds. Its ability to form biofilms grants it resistance to almost all antibiotics on the market. Answering the call for alternative treatments, our lab has been investigating the efficacy of 600 Da branched polyethylenimine (BPEI) as a β-lactam potentiator against bacterial biofilms. Our previous study showed promise against methicillin-resistant Staphylococcus epidermidis biofilms. This study extends our previous findings to eradicate a more virulent pathogen: MRSA biofilms. Microtiter minimum biofilm eradication concentration models, crystal violet assays, and electron microscopy images show synergistic effects between BPEI and ampicillin as a two-step mechanism: step one is the removal of the extracellular polymeric substances (EPS) to expose individual bacteria targets, and step two involves electrostatic interaction of BPEI with anionic teichoic acid in the cell wall to potentiate the antibiotic.

BPEI-Induced Delocalization of PBP4 Potentiates β-Lactams against MRSA

With its high morbidity rate and increasing resistance to treatment, methicillin-resistant Staphylococcus aureus (MRSA) is a grave concern in the medical field. In methicillin-susceptible strains, β-lactam antibiotics disable the penicillin binding proteins (PBPs) that cross-link the bacterial cell wall. However, methicillin-resistant strains have PBP2a and PBP4, which continue enzymatic activity in the presence of β-lactam antibiotics. The activity of PBP2a and PBP4 is linked to the presence of wall teichoic acid (WTA); thus, WTA has emerged as a target for antibiotic drug discovery. In this work, we disable WTA in situ using its anionic phosphodiester backbone to attract cationic branched polyethylenimine (BPEI). Data show that BPEI removes β-lactam resistance in common MRSA strains and clinical isolates. Fluorescence microscopy was used to investigate this mechanism of action. The results indicate that BPEI prevents the localization of PBP4 to the cell division septum, thereby changing the cellular morphology and inhibiting cell division. Although PBP4 is not required for septum formation, proper cell division and morphology require WTA; BPEI prevents this essential function. The combination of BPEI and β-lactams is bactericidal and synergistic. Because BPEI allows us to study the role of WTA in the cell wall without genetic mutation or altered translocation of biomolecules and/or their precursors, this approach can help revise existing paradigms regarding the role of WTA in prokaryotic biochemistry at every growth stage.

Antibiofilm Synergy of β-Lactams and Branched Polyethylenimine against Methicillin-Resistant Staphylococcus epidermidis

Microbial biofilms are ubiquitous in nature, and they pose a serious threat to public health. Staphylococcus epidermidis is the most common clinical isolate from healthcare- and medical device-related biofilm infections. No antibiotic currently on the market can eradicate pathogenic biofilms, which contain complex defense mechanisms composed of slimelike extracellular polymeric substances. Understanding the need to develop alternative approaches, we examine 600 Da branched polyethylenimine (BPEI) against methicillin-resistant Staphylococcus epidermidis (MRSE) biofilms. Here, a microtiter biofilm model is used to test the synergistic effects between the two components of our combination treatment: BPEI and β-lactam antibiotics. Electron microscopy was used to confirm the growth of MRSE biofilms from the model. Minimum biofilm eradication concentration assays, crystal violet assays, and biofilm kill curves suggest that BPEI exhibits antibiofilm activity and can potentiate β-lactams to eradicate MRSE biofilms.

Cationic Branched Polyethylenimine (BPEI) Disables Antibiotic Resistance in Methicillin-Resistant Staphylococcus epidermidis (MRSE)

Staphylococcus epidermidis is one of the most prevalent prokaryotic species on human skin and mucosal membranes that constitute the commensal flora. S. epidermidis has become one of the most common causes of primary bacteremia. Infections are difficult to diagnose because the pathogen has natural niches on human skin and the ability to adhere to inanimate surfaces via biofilms. Alarmingly, S. epidermidis has acquired resistance to many antibiotics, which presents a danger to human health. Known as methicillin-resistant S. epidermidis (MRSE), most clinical isolates of MRSE in North America exhibit β-lactam resistance primarily due to the presence of mecA, a gene that bestows β-lactam antibiotic resistance in a manner similar to methicillin-resistant Staphylococcus aureus (MRSA). MecA encodes for expression of penicillin-binding protein 2a (PBP2a), which is absent in β-lactam susceptible strains of S. epidermidis. We can disable this resistance factor in MRSE with 600-Da branched polyethylenimine (BPEI). Cationic BPEI targets anionic wall teichoic acid (WTA), an essential cofactor for proper functioning of PBP2a. We found that BPEI synergizes the activity of β-lactam antibiotics against MRSE. Growth curves suggest that the combination of BPEI and oxacillin is bactericidal. Electron micrographs indicate abnormalities in the cellular septa and cell walls of treated samples. Therefore, first-line clinical treatments can be effective against MRSE when used in combination with BPEI.

Targeting Wall Teichoic Acid in Situ with Branched Polyethylenimine Potentiates β-Lactam Efficacy against MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) is a medical concern. Here, we show that branched polyethylenimine (BPEI), a nontoxic, cationic polymer, restores MRSA's susceptibility to β-lactam antibiotics. Checkerboard assays with MRSA demonstrated synergy between BPEI and β-lactam antibiotics. A time-killing curve showed BPEI to be bactericidal in combination with oxacillin. BPEI did not potentiate efficacy with vancomycin, chloramphenicol, or linezolid. When exposed to BPEI, MRSA increased in size and had difficulty forming septa. BPEI electrostatically binds to wall teichoic acid (WTA), a cell wall anionic polymer of Gram-positive bacteria that is important for localization of certain cell wall proteins. Lack of potentiation in a WTA knockout mutant supports the WTA-based mechanism. These data suggest that BPEI may prevent proper localization of cell wall machinery by binding to WTA; leading to cell death when administered in combination with β-lactam antibiotics. Negligible in vitro toxicity suggests the combination could be a viable treatment option.

Follicular thyroid carcinoma with insular component: a retrospective case study, immunohistochemical analysis and literature review

This is a retrospective case study of a 61-year-old woman diagnosed with follicular thyroid carcinoma. The patient underwent thyroidectomy for the treatment of goitre after being admitted for shortness of breath. Microscopic and immunohistochemical studies were performed, which confirmed follicular carcinoma of the thyroid with an insular component. We also conducted a review of the literature on this uncommon entity.

Van der Woude syndrome: dentofacial features and implications for clinical practice

BACKGROUND

Van der Woude syndrome (VWS) is the most common clefting syndrome in humans. It is characterized by the association of congenital lower lip fistulae with cleft lip and/or cleft palate. VWS individuals have a high prevalence of hypodontia. Although caused by a single gene mutation, VWS has variable phenotypic expression. This study aimed to describe the range of clinical presentations in 22 individuals with VWS to facilitate its diagnosis.

METHODS

A retrospective study of 22 patients with a diagnosis of VWS was undertaken at the Australian Craniofacial Unit (ACFU) in Adelaide. Three extended families with affected members were included in the study cohort.

RESULTS

The overall prevalence of lip pits in this study cohort was 86%. Cleft phenotypes included bilateral cleft lip and palate (32%); unilateral cleft lip and palate (32%); submucous cleft palate (23%); and isolated cleft hard and soft palate (9%). Missing permanent teeth were reported in 86% of affected individuals.

CONCLUSIONS

Submucous cleft palate in VWS may go undiagnosed if the lower lip pits are not detected. Associated hypodontia and resultant malocclusions will also require management by a dental team.

The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOLMaster

BACKGROUND

Axial length and anterior chamber depth have been measured clinically using conventional ultrasound biometry. Recently, a non-contact device has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device.

METHODS

The axial length and anterior chamber depth were measured by two practitioners on a group of young subjects using the IOLMaster followed by a conventional ultrasound biometer operated by a third practitioner. The accommodation was controlled in ultrasound biometry through a full correction on the non-measured eye and a distant fixation target.

RESULTS

There was good repeatability and accuracy of axial length assessment. The mean difference between the IOLMaster and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster and the difference was not significant. The anterior chamber depth was repeatable but was shown to be deeper than the ultrasound results. The mean difference in anterior chamber depth between the IOLMaster and ultrasound biometry was 0.15 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggested that the former device is not measuring the axial anterior chamber depth.

CONCLUSIONS

The IOLMaster is a non-contact 'optical' A-scan which is simple to use and good for axial length assessment. The anterior chamber depth assessment should be further evaluated.

The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOLMaster

BACKGROUND

Axial length and anterior chamber depth have been measured clinically using conventional ultrasound biometry. Recently, a non-contact device has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device.

METHODS

The axial length and anterior chamber depth were measured by two practitioners on a group of young subjects using the IOLMaster followed by a conventional ultrasound biometer operated by a third practitioner. The accommodation was controlled in ultrasound biometry through a full correction on the non-measured eye and a distant fixation target.

RESULTS

There was good repeatability and accuracy of axial length assessment. The mean difference between the IOLMaster and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster and the difference was not significant. The anterior chamber depth was repeatable but was shown to be deeper than the ultrasound results. The mean difference in anterior chamber depth between the IOLMaster and ultrasound biometry was 0.15 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggested that the former device is not measuring the axial anterior chamber depth.

CONCLUSIONS

The IOLMaster is a non-contact 'optical' A-scan which is simple to use and good for axial length assessment. The anterior chamber depth assessment should be further evaluated.

Digital measurement of torsional eye movement due to postural change and its effect on reading performance

PURPOSE

Posture induced torsional eye movements have rarely been investigated. The current study made use of digital imaging technology to measure the cycloduction resulting from postural change. The effect of cycloduction on reading performance was also investigated.

METHODS

Thirty subjects were recruited and pictures of the right eye were captured using a digital camera at three postures, i.e. sitting, 90 degrees tilted to the right and 90 degrees tilted to the left. With the identification of a conjunctival landmark, torsional eye movement was measured. The subjects were then required to read a custom designed near chart while in those three postures, the reading card being rotated 90 degrees clockwise or 90 degrees anti-clockwise, to match with the tilting of the head. The reproducibility of the torsional eye movement and reading performance measure was determined in 12 of those 30 subjects.

RESULTS

Incycloduction was induced when tilting to the right and excycloduction when tilting to the left. This method was found to be reproducible with the 95% confidence limits of 0.80 degrees between visits. The mean incycloduction induced was 6.50 degrees (SD 1.51 degrees ) and 6.41 degrees (SD 1.46 degrees ) for excycloduction. No significant difference in amount was demonstrated (paired t-test: t = 0.624, P = 0.538). No significant difference was found in the reading scores at various postures (Repeated measures ANOVA: df = 2, F = 1.881, P = 0.162).

CONCLUSIONS

The results presented here demonstrate that we have developed an objective and instantaneous method with good precision, which could be applied in other studies that require the measurement of torsional eye movements. The induced cycloduction did not affect the reading performance.

Molecular biology of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the predominant histologic subtype of esophageal cancer and characterized by high mortality rate and geographic differences in incidence. With the advances in the field of molecular biology, our understanding of the pathogenesis, epidemiology and behavior of ESCC continues to evolve. The recent development includes research in etiopathogenesis (viruses and cancer susceptibility genes), keratins, tumor related genes (oncogenes, tumor suppressor genes, genes involved in metastasis and apoptosis genes), proliferation-related factors (nuclear proteins, flow cytometry/morphometry, argyrophilic nucleolar organizer region) and factors related to metastases (cell adhesion molecules and enzymes related to degradation of extracellular matrix). There are ranges of molecular techniques potentially available to complement the traditional approaches in the management of ESCC. On the other hand, critics are needed in the interpretation and translation of these research findings from laboratories to clinics. Further investigations, education and collaborations between the various scientific and clinical disciplines are important to successful application of these molecular findings aiming at improving management of patients with ESCC.

A preliminary study on the ocular blood flow (OBF) of Hong Kong Chinese

The Ocular Blood Flow (OBF) Tonometer is an objective instrument to measure the Pulsatile Ocular Blood Flow (POBF), Pulse Amplitude (PA) and Pulse Rate (PR). It also provides the minimum intraocular pressure (IOPmin) simultaneously. This preliminary study applied the OBF Tonometer on 74 Hong Kong Chinese. They had their POBF measured followed by the Goldmann Applanation Tonometer (GAT). The OBF tonometer overestimates the IOP slightly. The average POBF result was smaller (661.2 microliters/min) than the previous studies. The effect of myopia of our sample (mean spherical equivalent -4.27 D) could be one of the contributing factors. Other factors include age and racial difference. Twenty-two subjects had their POBF measured again by the same practitioner and different practitioner for the reproducibility variation assessments. The POBF, PA and IOPmin were found to be repeatable between sessions. The POBF "norm" in Hong Kong Chinese needs to be established from a larger sample size and from a comparison on an age and refraction matched Caucasian group.

The characteristics of near prism induced fixation disparity curve in Hong Kong Chinese

The characteristics of prism induced fixation disparity curve at near were studied in 56 asymptomatic young adult Hong Kong Chinese (average age 21 years). The percentage distribution of types of fixation disparity curves was found to be similar to some previous studies, with a higher prevalence of Type I curve (64.3%), followed by Type II (28.6%) and Type III (7.1%) curves. No Type IV curve was revealed from the sample. Two modified measurement approaches were applied to study the effect of measurement techniques on the parameters of fixation disparity curve obtained. A thorough description of the techniques was given. Although a significant difference in the x- and y-intercepts was obtained between different methods, the curve type and slope were not affected. The average y-intercepts (fixation disparity) were 2.72 min of arc and 3.54 min of arc from two methods respectively. Forty-one subjects had x-intercept (associated phoria) found from the curve. The average values were 2.42 delta base-out and 3.54 delta base-out from two methods respectively.

The aging effect on corneal curvature and the validity of Javal's rule in Hong Kong Chinese

PURPOSE

The current study compared the central corneal curvature and the refractive error of Hong Kong Chinese to study the validity of Javal's rule.

METHODS

Subjects without corneal pathology were recruited at different age ranges. Their refractive error and the corneal curvature were measured and compared for the right eye only. Two instruments were used for the measurement of corneal curvature including a conventional Bausch & Lomb (B&L) keratometer and a computer-assisted videokeratoscope (TMS-1).

RESULTS

Subjects age ranged from 21 years to 77 years were recruited and were categorized into five groups according to age. The Bausch & Lomb keratometer was found to provide corneal information similar to that from the TMS-1. The corneal astigmatism was found to change from with-the-rule to against-the-rule with advancing age. The spectacle astigmatism followed a similar trend. There was a hyperopic shift in the spherical component of the refractive error with aging as well. A regression equation: Spectacle astigmatism = 0.93 (Corneal astigmatism) + (-0.58D x 90) was found, which is similar to the simplified Javal's rule. There was a shift of 1.03D in hyperopia (spherical equivalent) for each decade.

CONCLUSIONS

Both the corneal and spectacle astigmatism demonstrated a shift from with-the-rule to against-the-rule with age. The simplified Javal's rule is more suitable for predicting the spectacle astigmatism from corneal astigmatism in Hong Kong Chinese.

Could a cycloplegic agent be replaced by a fogging or a corrective lens in the biometric measurement of the crystalline lens?

This study investigated whether a fogging or a corrective lens could be used to replace a cycloplegic agent in the ultrasonic measurement of crystalline lens thickness in myopia. A group of 28 Hong Kong Chinese adults with myopia was recruited. The crystalline lens thickness of the examined eye was measured by A-scan ultrasonography while the fixating eye was in one of three conditions: fog (+2.00 D fogging lens), full corrective lens, or cycloplegia (50 minutes after instillation of 1% cyclopentolate HCl). We found that the mean lens thickness was significantly different between the three conditions in our myopic subjects. The mean crystalline lens thickness under fogging and corrective lens conditions was significantly greater than the cycloplegic condition by 0.09 mm and 0.11 mm, respectively. The 95% limits of agreement compared to cycloplegia (fogging: -0.32 to +0.14; corrective: -0.35 to +0.13) showed marked intersubject variability, indicating that there is a risk of overestimating the lens thickness when substituting cycloplegia with either a fogging or a corrective lens.

The corneal-thickness profile in Hong Kong Chinese

PURPOSE

This study investigated the topographic corneal thickness in four groups of Hong Kong Chinese.

METHODS

The corneal thickness was determined with an ultrasound pachometer mounted on a X-Y plate. A head rest was used to reduce further any movement from the subject during the measurement. After the central cornea was measured, the peripheral cornea was determined on nasal, temporal, superior, and inferior regions, 2 and 5 mm from the corneal center.

RESULTS

The corneal thickness was not significantly different between the right and left eyes. For the right eye, there was no significant thickness difference for the four quadrants at a midperipheral and peripheral region, respectively. There was a general thinning of the corneal thickness at all regions from aging but no difference between the genders.

CONCLUSION

The corneal thickness in our subjects was similar to that in other studies. The mean central corneal thickness varied from 541.7 (m to 560.8 microm, dependent on age. This study provides some information for the future studies of Chinese corneal thickness.

Ret oncogene activation in papillary thyroid carcinoma: prevalence and implication on the histological parameters

The Ret proto-oncogene is known to be rearranged in papillary carcinoma of the thyroid. The aim of this study was to investigate the in situ expression of Ret mRNA in thyroid tumors. Formalin-fixed, paraffin-embedded tissue specimens from 45 thyroid lesions were examined by in situ hybridization using manual capillary action technology (MicroProbe Staining System) and a 52-base synthetic biotinylated oligonucleotide probe complementary to the tyrosine-kinase domain of Ret proto-oncogene. The clinicopathological features of these patients with thyroid lesions also were noted. Ret was noted in 17 (43%) of 40 papillary carcinomas. In contrast, none of the three follicular carcinomas, follicular adenoma, nodular hyperplasia, and normal thyroids, showed evidence of Ret mRNA. Our results showed that, in papillary thyroid carcinoma, there is an important role of Ret activation. The Ret staining could be a useful marker for papillary carcinoma.

The effect of an artificially-elevated intraocular pressure on corneal thickness in Chinese eye

We measured the central corneal thickness and the applanation intraocular pressure (IOP) on 45 Hong Kong Chinese. There was no obvious relationship between these two parameters, as different from other literatures. It could be due to either a limited number of subjects with a high IOP level (only six subjects with IOP > or = 22 mmHg), or Chinese has a thicker central cornea in general. The mean central cornea of our subjects was thicker (566 +/- 36 microns) than some previous findings. Thirty subjects had their intraocular pressure further increased by adopting a 40 degrees head-down posture. Their IOP and topographic corneal thickness were measured again. There was no significant change in the central corneal thickness even though the IOP was elevated by 11.7 mmHg. However the nasal cornea demonstrated a thinning effect (by some 18 microns) during the IOP elevation but it returned to the pre-inverted level after returning to a sitting posture for 5 min. Further investigation with more corneal regions being measured would be valuable to evaluate the in vivo effect of IOP elevation from glaucoma attack on corneal thickness.

Does the change of anterior chamber depth or/and episcleral venous pressure cause intraocular pressure change in postural variation?

PURPOSE

Previous studies have found that the intraocular pressure (IOP) variation from postural change is due to the obstruction of aqueous outflow by an increase in episcleral venous pressure. This study investigated if any shift of anterior lens position from postural variation would be another contributing factor.

METHODS

Thirty-three Chinese subjects were recruited with their IOP and anterior chamber depth (ACD) measured in the sitting, supine, and prone postures. The IOP was measured using a Pulsair 2000 noncontact tonometer and ACD with a Nidek US-2000 EchoScan unit.

RESULTS

The highest IOP was obtained in the prone position and this value was significantly different from the IOP obtained in other postures, whereas there was no significant difference in ACD.

CONCLUSIONS

Because no significant variation in ACD was demonstrated, the prone and supine IOP variation could be due to something other than the change in lens position. However, a higher IOP in the prone position rather than in the supine position also suggests that it is not merely the episcleral venous pressure causing the IOP change. Investigation of the entire iris profile at different postures would be more informative in future studies.

Measurement of posterior corneal asphericity on Hong Kong Chinese: a pilot study

The posterior corneal p-value and apical radius of 60 Hong Kong Chinese were assessed. The values were derived based on the information of the anterior corneal topography and the corneal thickness in different regions. The mean posterior corneal apical radius along the horizontal meridian was 6.51 mm (SD +/- 0.40 mm) and the p-value was 0.34 (SD +/- 0.38). The apical radius is greater while the p-value is smaller than a previous study using a similar principle. This may indicate a flatter posterior cornea and greater peripheral flattening in Hong Kong Chinese. No significant difference between the nasal and temporal corneal thickness, nasal and temporal posterior p-value and apical radius was demonstrated. The right and left eyes were also similar in different ocular parameters apart from a smaller anterior corneal p-value on the right eye (R eye: 0.70 +/- 0.13; L eye: 0.67 +/- 0.12), but the difference may not be significant clinically. The method used here is simple and the generation of posterior corneal topography is informative.

The effect of an artificially elevated intraocular pressure on the central corneal curvature

Twenty-three optometry students with normal corneal condition were recruited. The intraocular pressure and central corneal curvature of the right eye were measured in a sitting and a 30 degrees head-down posture. The mean (standard deviation) IOPs before and during posture change were 15.6 (2.4) mmHg and 22.1 (2.3) mmHg respectively. This 6.5 mmHg mean rise in IOP was found to be statistically significant which is similar to the results from previous studies. The mean changes in radius of corneal curvature and the orientation of the axis of the vertical principal meridian were 0.02 mm (SD 0.025 mm) and 2.4 degrees (SD 10.4 degrees) respectively. No significant variation was demonstrated on these keratometric results due to the 30 degrees head-down posture. The maximum change in radius of curvature was only 0.055 mm for one subject. Perhaps this amount of pressure rise was not sufficient enough to distort the corneal surface centrally. Another possibility could be an even distribution of the elevated pressure around the cornea, or the distribution of pressure is not even but could not be revealed by a conventional keratometer.

A pilot study on the measurement of central posterior corneal radius in Hong Kong Chinese using Purkinje image technique

The central posterior corneal radius was measured by assessing the first and second Purkinje images produced from a modified keratometer. This method was initially assessed by measuring five PMMA lens buttons with back surface radii from 6.2 mm to 7.0 mm. It was reasonably accurate when compared with the measurements made using a conventional radiuscope. The technique was found to be repeatable for human subjects measured on three separate occasions. The mean central posterior corneal radii from a group of 30 Hong Kong Chinese were 6.64 mm (SE 0.05 mm) and 6.39 mm (SE 0.05 mm) along the horizontal and vertical meridians respectively. These results are similar to previous studies using a similar technique. The posterior corneal radii were found to be similar for right and left eyes and there were no gender differences.

Effect of naturally occurring visual acuity differences between two eyes in stereoacuity

Stereoacuity was measured in 30 subjects with a naturally occurring visual acuity (VA) difference between the eyes. The stereoacuity was measured by a modified Howard's apparatus using the staircase method and VA was measured with log MAR charts. Stereoacuity was worse in subjects with a large VA difference between the two eyes; the correlation between stereoacuity and VA difference was significant (r = 0.76, P < 0.001). Neither the VA of the worse eye nor of the better eye contributed to the reduction in stereoacuity. The deterioration was more obvious if VA difference between the two eyes was one line or more (correlation coefficient, r= 0.88, P < 0.001). This study also reinforces the use of a > or = 70% stereothreshold when attempt stereoacuity results to compare with other studies.

Application of a modified keratometer in the study of corneal topography on Chinese subjects

A corneal topography study was carried out on Hong Kong Chinese subjects using a modified keratometer. The Chinese corneal topography measured by this modified keratometer was similar to other studies using the Wesley-Jessen Photo Electronic Keratoscopy (PEK) System 2000. The mean p-values along the horizontal meridian and the vertical meridian were 0.82 and 0.87, respectively. A negative correlation was found between the p-value and the central corneal radius along the horizontal meridian which may indicate that a steeper central cornea will have a greater p-value. However, the correlation coefficient of 0.56 was not too certain for this conclusion to be drawn. A difference of 0.04 was found between the horizontal p-value and the vertical p-value, which may be a result of the tight lid tension along the vertical meridian. This modified keratometer can be considered as an inexpensive instrument for the study of corneal topography.

A hand-held keratometer

Using model eyes the sensitivity to orientation of an Alcon hand-held autokeratometer was assessed after calibration with steel balls. It was concluded that the keratometer should be used in a vertical position (6:00/12:00) in order for axis references to be accurate. Corneal curvature of optometry students was measured using the autokeratometer and a Bausch and Lomb keratometer. The results showed that the autokeratometer was similar to the Bausch and Lomb keratometer in measuring the vertical and horizontal principal meridians, and the axis of the vertical principal meridian. This hand-held keratometer is useful for screening purposes and measuring corneas of infants.

Derivation of corneal flattening factor, p-value

A mathematical equation was derived to calculate the corneal p-value based on the central and peripheral corneal radii and the corresponding semichord diameters. The calculation was simplified by a computer program written using GWBASIC. The accuracy of corneal p-value generated from this program was checked with Douthwaite's modified keratometer with good correlation. This program could be used to find out the corneal p-value and apical radius ro for any topographic keratometer which only provides central and peripheral radii without any information of the p-value and apical radius.

Three month study of changes in the cornea after computer-determined and conventionally-determined contact lens fitting

The conventional rigid-lens fitting method uses fluorescein to assess the tear layer beneath a trial lens on the corneal surface. A more advanced technique, which uses a computer program to determine the back surface specifications of a contact lens from a pre-set tear layer thickness, has been studied. No significant difference was found in terms of corneal physiological changes between the conventionally determined contact lenses and computer-determined contact lenses after a three-month wearing period. The results suggest that there is little difference in the two methods of fitting. However, the computer determined method was found to be more efficient in terms of chair time, and also can aid inexperienced rigid lens practitioners to select the appropriate lens back surface curves.

Rigid lens fitting made easier using a modified keratometer

After simple modification, a keratometer can measure both the central and peripheral regions of the cornea. The apical radius and p-value of the cornea can be determined with this information using a computer program. This computer program suggests lens parameters similar to those chosen by conventional methods in rigid lens fitting. The computerized fitting method is also applicable to Chinese subjects.

Sudden death associated with cardiac inflammatory pseudotumour

We report a case of cardiac inflammatory pseudotumour which we believe caused sudden death in a previously healthy 55-year-old Chinese female. The features of inflammatory pseudotumours are briefly reviewed. Cardiac lesions are very rare, have only been reported in children before, and have not been associated with sudden death.

Adult onset nemaline myopathy

A 47-year-old man had symptoms of nemaline myopathy for approximately 1 year. There were marked elevations of creatine kinase, a feature not previously described. Examination of the nervous system at autopsy failed to reveal any abnormalities.