92 CONTINUING TO ‘BE HIP’: ORTHOGERIATRIC SERVICE IMPROVEMENTS IN 2021

Background

Scotland first demonstrated that adherence to nationally agreed hip fracture standards improve patient survival, reduces the duration of admission, and reduces the need for high dependency care. Our study aims to assess adherence to the Irish Hip Fracture Standards (IHFS) in our hospital for 2021 amidst the COVID-19 pandemic, translating to improved clinical outcomes for our patients.

Methods

The IHF database was retrospectively analysed, comparing quarters 1-4 in 2021 with our 2020 results.

Results

IHFS1, patient time to the ward < 4hours, was maintained at 67% in 2021 versus 71% overall in 2020. There was improvement in IHFS2, time to surgery within 48 hours, up to 73% in 2021 versus 66% in 2020. IHFS3 was 4% in 2021 versus 3% overall in 2020. Further improvements were noted for IHFS4, with 95% of patients reviewed by a Geriatrician in 2021 versus 87% in 2020. IHFS5 also improved with 97% of patients receiving a bone health assessment in 2021 versus 87% in 2020. Moreover, IHFS6, improved with 97% of patients undergoing a specialised falls assessment in 2021 versus 87% in 2020.

Conclusion

The improvement in 2021 figures is reflective of the return of redeployed services during the COVID-19 pandemic inclusive of the Orthogeriatric Service, the Fracture Liaison Service Advanced Nurse Practitioner, the Trauma Co-ordinator, and the specialist Orthopaedic ward complete with its Orthopaedic nurses and Multi-Disciplinary Team, and improved Emergency Department pathways. These continued improvements in the IHFS further emphasise that success is dependent on a team that is joined at the hip

258 RISING TO THE CHALLENGE: ORTHOGERIATRIC SERVICE IMPROVEMENT AND COVID-19

Background

Nationally agreed hip fracture standards have contributed to the improvement of outcomes in hip fracture patients. In 2020, our hospital was awarded “The Golden Hip” for achieving highest compliance with Irish Hip Fracture Standards (IHFS) nationally for 2019.

Methods

Data from the Irish Hip Fracture Database (IHFD)was retrospectively analysed to assess our performance in 2020 versus 2019 in hip fracture patients over sixty. Multiple quality improvement interventions were put in place throughout 2019 to ensure improvement in IHFS1-6 compliance: Creation of the Hip Fracture Pathway Subgroup, IHFS 1 Breaches Audit, Orthogeriatric input at Orthopaedic inductions, weekly Multi-disciplinary Team meetings, a Nutritional Hip Fracture Pathway and addition of the Fracture Liaison Service Advanced Nurse Practitioner.

Results

There were 239 hip fracture patients in 2020 vs 249 in 2019. IHFS1 compliance improved with the percentage of patients admitted to the Orthopaedic ward within 4 hours increasing to 71% in 2020 from 56% in 2019. There was improvement in IHFS2-time to surgery &lt;48 hours- 66% in 2020 vs 60% in 2019. IHFS3-pressure ulcer rate-was at the national average, 3% in 2020 vs 2% in 2019. IHFS4 (reviewed by a Geriatrician), IHFS5 (received a bone health assessment) and IHFS6 (received a specialised falls assessment) were lower overall; 87% in 2020 vs 98% in 2019. For all quarters (Q),43% of patients met all IHFS in our hospital in 2020 vs 32% in 2019, resulting in €90,000 in Best Practice Tariff funding.

Conclusion

Lower results for IHFS 4,5 and 6 reflect the arrival of the COVID-19 pandemic which led to redeployment of the Orthogeriatric Service and redeployment of the MDT from end of Q1 to Q3. When services in 2020 were preserved,1 in 2 hip fracture patients met all IHFS, vs 1 in 3 patients in 2019. Despite the pandemic, we continued to achieve the highest level of IHFS compliance nationally, being awarded a second consecutive “Golden Hip” for 2020.

272 PHYSIOTHERAPISTS' EXPERIENCES OF WORKING IN RESIDENTIAL CARE IN THE REPUBLIC OF IRELAND DURING COVID-19

Background

COVID-19 was officially declared a pandemic in March 2020. Social distancing and visiting restrictions were introduced in Irish residential care units in March 2020. The impact of COVID-19 and associated restrictions on physiotherapists working in residential care in the Republic of Ireland (ROI) is unknown. This study aimed to explore the experience of physiotherapists working in residential care units in the ROI during the COVID-19 pandemic.

Methods

A qualitative phenomenological study design was used. Physiotherapists working in residential care units were invited to participate in one-to-one semi-structured interviews from December 2021 to March 2022. Participants were recruited via purposive and snowball sampling. Data were analysed using reflexive thematic analysis by two independent reviewers.

Results

Seven one-to-one semi-structured interviews were conducted among five female and two male physiotherapists. Four major themes emerged: (i) service adaptation (ii) communication (iii) physical and emotional impact of COVID-19 pandemic on staff and (iv) physical and emotional impact of COVID-19 pandemic on residents. A number of subthemes were identified under each theme. Participants experienced changes in service delivery including redeployment, reduced resident contact and social distancing. These changes resulted in innovation, mainly through telehealth. Participants felt communication from managers could be improved through clarity regarding protocol changes. The pandemic stimulated enhanced inter-professional communication among physiotherapists. Some participants contracted COVID-19 resulting in residual physical impairments. Participants were affected emotionally through the increased stress experienced due to COVID-19 restrictions. Residents experienced isolation due to visiting restrictions. Due to reduced physiotherapy input participants observed reduced physical functioning among residents.

Conclusion

COVID-19 and its associated restrictions had a profound impact on physiotherapists working in residential care units as well as on residents. The extent of this impact is only beginning to emerge. Planning for future pandemics should consider the long-term physical and emotional consequences of restrictions on both physiotherapists and residents.

Evidence of degradation of hair corticosterone in museum specimens

Researchers increasingly rely on non-invasive physiological indices, such as glucocorticoid (GC) levels, to interpret how vertebrates respond to changes in their environment. Recently, hair GCs have been of particular interest, because they are presumed stable over long periods of storage, which may facilitate the study of large-scale spatial and temporal patterns of stress in mammals. In the current study, we evaluated the stability of hair corticosterone levels in museum specimens, and the potential effects of different museum curation treatments. Using deer mouse (Peromyscus maniculatus) specimens collected from Vancouver Island (11 sites, 82 individuals) over 76 years, we found that specimens collected earlier in the 20th century had lower hair corticosterone than more recently collected specimens. These results suggest that hair hormone levels may not be stable over decades of storage time. We then subjected hair samples collected from white-footed mouse (Peromyscus leucopus, n = 36) to 3 different museum curation treatments, and found that borax lowered hair corticosterone levels relative to control samples, but air drying samples, or treating them with turpentine had no effect. Our results present a source of concern for the use of museum specimens for hair hormone analysis, and for studying long term trends in glucocorticoid levels.

Combined use of modulated ultrasound and electric current stimulation for diabetic foot ulcers: a case series

OBJECTIVE

Diabetic foot ulcers (DFUs) are a significant challenge in wound care practice. Our aim was to evaluate the combined use of of two therapies, ultrasound and electrostimulation, in the treatment of DFUs.

METHOD

This study employed a prospective, non-comparative, case series design, undertaken in a podiatry-led diabetic foot clinic, in an acute hospital setting, in an urban location in Ireland. We recruited patinets with hard-to-heal DFUs who were treated twice a week with combined modulated ultrasound and electric current stimulation.

RESULTS

We recruited seven patients with eight chronic DFUs. A mean wound size reduction of 71% was achieved and there were no adverse reactions to the therapy.

CONCLUSION

The results of this small case series indicate that combined modulated ultrasound and electric current stimulation offers promise as an adjunct therapy for DFUs. Further large scale trials are now warranted.

A STUDY OF THE IMAGE QUALITY OF COMPUTED TOMOGRAPHY ADAPTIVE STATISTICAL ITERATIVE RECONSTRUCTED BRAIN IMAGES USING SUBJECTIVE AND OBJECTIVE METHODS

The recent reintroduction of iterative reconstruction in computed tomography has facilitated the realisation of major dose saving. The aim of this article was to investigate the possibility of achieving further savings at a site with well-established Adaptive Statistical iterative Reconstruction (ASiR™) (GE Healthcare) brain protocols. An adult patient study was conducted with observers making visual grading assessments using image quality criteria, which were compared with the frequency domain metrics, noise power spectrum and modulation transfer function. Subjective image quality equivalency was found in the 40-70% ASiR™ range, leading to the proposal of ranges for the objective metrics defining acceptable image quality. Based on the findings of both the patient-based and objective studies of the ASiR™/tube-current combinations tested, 60%/305 mA was found to fall within all, but one, of these ranges. Therefore, it is recommended that an ASiR™ level of 60%, with a noise index of 12.20, is a viable alternative to the currently used protocol featuring a 40% ASiR™ level and a noise index of 11.20, potentially representing a 16% dose saving.

A Quantitative Measure of Field Illumination

In this paper, we describe a statistically based algorithm to quantify the uniformity of illumination in an optical light microscopy imaging system that outputs a single quality factor (QF) score. The importance of homogeneous field illumination in quantitative light microscopy is well understood and often checked. However, there is currently no standard automatic quantitative measure of the uniformity of the field illumination. Images from 89 different laser-scanning confocal microscopes (LSCMs), which were collected as part of an international study on microscope quality assessment, were used as a "training" set to build the algorithm. To validate the algorithm and verify its robustness, images from 33 additional microscopes, including LSCM and wide-field (WF) microscopes, were used. The statistical paradigm used for developing the quality scoring scale was a regression approach to supervised learning. Three intensity profiles across each image-2 corner-to-corner diagonals and a center horizontal-were used to generate pixel-intensity data. All of the lines passed through the center of the image. The intensity profile data then were converted into a single-field illumination QF score in the range of 0-100, with 0 having extreme variation, and therefore, essentially unusable, and 100 having no deviation, i.e., straight lines with a constant uniform intensity. Empirically, a QF ≥ 83 was determined to be the minimum acceptable value based on manufacturer acceptance tests and reasonably achievable values. This new QF is an invaluable metric to ascertain objectively and easily the uniformity of illumination quality, provide a traceable reference for monitoring field uniformity over time, and make a direct comparison among different microscopes. The QF can also be used as an indicator of system failure and the need for alignment or service of the instrument.

Transcriptional dysregulation of inflammatory/immune pathways after active vaccination against Huntington's disease

Immunotherapy, both active and passive, is increasingly recognized as a powerful approach to a wide range of diseases, including Alzheimer's and Parkinson's. Huntington's disease (HD), an autosomal dominant disorder triggered by misfolding of huntingtin (HTT) protein with an expanded polyglutamine tract, could also benefit from this approach. Individuals can be identified genetically at the earliest stages of disease, and there may be particular benefits to a therapy that can target peripheral tissues in addition to brain. In this active vaccination study, we first examined safety and immunogenicity for a broad series of peptide, protein and DNA plasmid immunization protocols, using fragment (R6/1), and knock-in (zQ175) models. No safety issues were found. The strongest and most uniform immune response was to a combination of three non-overlapping HTT Exon1 coded peptides, conjugated to KLH, delivered with alum adjuvant. An N586-82Q plasmid, delivered via gene gun, also showed ELISA responses, mainly in the zQ175 strain, but with more variability, and less robust responses in HD compared with wild-type controls. Transcriptome profiling of spleens from the triple peptide-immunized cohort showed substantial HD-specific differences including differential activation of genes associated with innate immune responses, absence of negative feedback control of gene expression by regulators, a temporal dysregulation of innate immune responses and transcriptional repression of genes associated with memory T cell responses. These studies highlight critical issues for immunotherapy and HD disease management in general.

Angiogenesis QTL on Mouse Chromosome 8 Colocalizes with Differential β-Defensin Expression

Identification of genetic factors that modify complex traits is often complicated by gene-environment interactions that contribute to the observed phenotype. In model systems, the phenotypic outcomes quantified are typically traits that maximize observed variance, which in turn, should maximize the detection of quantitative trait loci (QTL) in subsequent mapping studies. However, when the observed trait is dependent on multiple interacting factors, it can complicate genetic analysis, reducing the likelihood that the modifying mutation will ultimately be found. Alternatively, by focusing on intermediate phenotypes of a larger condition, we can reduce a model's complexity, which will, in turn, limit the number of QTL that contribute to variance. We used a novel method to follow angiogenesis in mice that reduces environmental variance by measuring endothelial cell growth from culture of isolated skin biopsies that varies depending on the genetic source of the tissue. This method, in combination with a backcross breeding strategy, is intended to reduce genetic complexity and limit the phenotypic effects to fewer modifier loci. We determined that our approach was an efficient means to generate recombinant progeny and used this cohort to map a novel s.c. angiogenesis QTL to proximal mouse chromosome (Chr.) 8 with suggestive QTL on Chr. 2 and 7. Global mRNA expression analysis of samples from parental reference strains revealed β-defensins as potential candidate genes for future study.

The maternal autoimmune environment affects the social behavior of offspring

Autism spectrum disorders (ASD) are neurodevelopmental disorders with unknown etiology. BTBR-T(+)tf/J (BTBR) mice, a mouse strain with behaviors that resemble autism and with elevated levels of anti-brain antibodies (Abs), have enhanced activation of peripheral B cells and CD4(+) T cells and an expanded percentage of CD4(+) T cells expressing Vβ6 chains. The CD4(+)CD25(+)Vβ6(+) and Vβ6-splenic cells of BTBR mice have elevated levels of IL-4, IFN-γ and IL-17, but there appears to be no preferential CD4(+) T subset skewing/polarization. The high level of IgG production by BTBR B cells was dependent on T cells from BTBR mice. The CD4(+) T cells of BTBR mice, especially those expressing Vβ6 become spontaneously activated and expanded in an autoimmune-like manner, which occurred in both BTBR and B6 hosts that received an equal number of BTBR and B6 bone marrow cells. BTBR mice also have an elevated percentage of peripheral blood neutrophils, which may represent their elevated inflammatory state. B6 offspring derived from B6 dams that were gestationally injected with purified IgG from sera of BTBR mice, but not IgG of B6 mice, developed significantly impaired social behavior. Additionally, B6 offspring that developed in BTBR dams had impaired social behavior, while BTBR offspring that developed in B6 dams had improved social behavior. All of the immunological and behavioral parameters of BTBR mice were compared with those of B6 mice, which have relatively normal behaviors. The results indicate maternal Abs and possibly other maternal influences affect the social behavior of offspring.

Longitudinal study of aortic isthmus Doppler in appropriately grown and small-for-gestational-age fetuses with normal and abnormal umbilical artery Doppler

OBJECTIVE

To establish reference ranges using longitudinal data for aortic isthmus (AoI) Doppler indices in appropriate-for-gestational-age (AGA) fetuses and to document the longitudinal trends in a cohort of small-for-gestational-age (SGA) fetuses with normal umbilical artery Doppler and in fetuses with intrauterine growth restriction (IUGR) and abnormal umbilical artery Doppler.

METHODS

AoI Doppler reference ranges were established from longitudinal data on 72 AGA singleton fetuses. Reliability of AoI Doppler flow measurements at two different sites and reproducibility between two operators was reviewed. A prospective longitudinal study of AoI Doppler indices in 48 SGA fetuses with normal umbilical artery Doppler and 10 IUGR fetuses was performed.

RESULTS

The AoI pulsatility index (PI) and peak systolic velocity (PSV) in AGA fetuses showed a significant increase with gestational age. Analysis of intra- and interoperator variability revealed no significant mean difference in measurements of AoI-PI or AoI-PSV. Observations of AoI-PI and AoI-PSV from SGA fetuses did not differ significantly from those of AGA or IUGR fetuses. Retrograde flow in the AoI did not predate changes in the ductus venosus in IUGR fetuses.

CONCLUSIONS

Reference ranges for fetal AoI Doppler parameters in AGA fetuses constructed using longitudinal data are consistent with those obtained from cross-sectional data. The AoI Doppler parameters in SGA fetuses did not differ from those in AGA fetuses. Preterm IUGR fetuses did not manifest alterations in AoI-PI or AoI-PSV prior to changes in biophysical profile or ductus venosus Doppler. Further large-scale prospective studies are needed to determine whether AoI Doppler parameters are of any value in timing delivery or reducing adverse neurodevelopmental outcome.

Food safety and products from aquaculture

Aquaculture is currently one of the fastest growing food production systems in the world with production increasing at an average rate of 9.6% per year over the past decade. As world fish stocks are reaching the limits of exploitation, we shall rely to a far greater extent on products from aquaculture as food sources of high nutritional value. Approximately 90% of global aquaculture production is based in Asia, where it provides an important source of dietary animal protein of the region and income for millions of small-scale farmers. Commercial aquaculture contributes significantly to the economies of many producing countries, where highly valued species are a major source of foreign. Many different aquaculture systems exist world wide, ranging from small family-sized fish ponds to intensive cage culture industries as used in salmon fishing. There has been an expansion in the use of integrated farming systems, especially in Asia, where animal and human faeces are used to fertilise ponds. This paper will review global aquaculture systems used in the production of finfish and crustaceans and will focus on potential hazards arising from biological contamination of products that pose risks to public health.

IL-10 is pathogenic during the development of coxsackievirus B4-induced chronic pancreatitis

Using a mouse model of coxsackievirus B4 (CVB4-V)-induced chronic pancreatitis, we investigated whether cytokines are involved in the progression of acute disease to chronic inflammatory disease. We show that IL-10 contributed to the development of chronic pancreatitis since acute disease resolved when IL-10 was absent or when IL-10 signaling was disrupted. We explored the underlying mechanisms by which IL-10 affected disease progression, using a novel approach to assess immunological events occurring in situ. Multiple markers that define functional innate immune responses and functional T cell responses were monitored over the course of CVB4-V infection of wild-type and IL-10 knockout mice, using a multiplex transcriptional profiling approach. We show that high levels of IL-10 early during infection were associated with delayed innate and T cell responses. Furthermore, high IL-10 production correlated with altered kinetics of T regulatory responses indicating a disruption in the balance between effector and regulatory T cell responses.

Prevalence of drug-resistant and nonsubtype B HIV strains in antiretroviral-naïve, HIV-infected individuals in New York State

The duration of HIV infection is usually unknown for most patients entering into HIV care. Data on the frequency at which resistance mutations are detected in these patients are needed to support practical guidance on the use of resistance testing in this clinical situation. Furthermore, little is known about HIV subtype diversity in much of the United States. Therefore, we analyzed the prevalence of drug resistance mutations and nonsubtype B strains of HIV among antiretroviral-naïve individuals presenting for HIV care in New York State between September 2000 and January 2004. Sequences were obtained using a commercial HIV genotyping assay. Seventeen of 151 subjects (11.3%; 95% confidence interval 7.2%-17.3%) had at least one drug-resistance mutation, including 5 subjects with fewer than 200 CD4(+) T cells, indicative of advanced infection. Nucleoside reverse transcriptase inhibitor, non-nucleoside reverse transcriptase inhibitor, and protease inhibitor resistance mutations were detected in 6.6%, 5.3%, and 0.7% of subjects, respectively. Subjects from New York City-based clinics were less likely to have resistant virus than subjects from clinics elsewhere in New York State. Nonsubtype B strains of HIV were detected in 9 (6.0%) individuals and were associated with heterosexual contact. Two nonsubtype B strains from this cohort also carried drug-resistance mutations. These data indicate that drug-resistant virus is frequently detected in antiretroviral-naïve individuals entering HIV care in New York State. Furthermore, a diverse set of nonsubtype B strains were identified and evidence suggests that nonsubtype B strains, including those carrying drug-resistance mutations, are being transmitted in New York State.

Stress and dress: investigating the relationship between social anxiety and appearance management among gay and straight men

This research project explores the relationship between social anxiety and appearance management behaviors (AMB), including both routine and non-routine, among gay and straight men and women. Prior research had found links between AMB and stress (Reilly & Rudd, 2002), stress and (perceived) discrimination (Lee, 1997; Savin-Williams, 1994), and sexual orientation and weight (Brand, Rothblum, & Solom, 1992). An argument is made that links stress with AMB using the foundation of Social Comparison Theory (Festinger, 1954) as a guide. Research questions investigated were: (1) Is there a correlation between stress and AMB; (2) Is there a significant difference between body mass indices of men and women of differing sexual orientations; (3) How do AMB differ between those with gay and straight orientations; and (4) How do AMB differ between men and women? Using a survey design, a questionnaire was posted on the Internet. Measures included the Rudd/Lennon Appearance Management Scale of Routine and Risky Behaviors and the Liebowitz Social Anxiety Scale. A total of 365 usable forms were completed. Results show that social anxiety is positively correlated with non-routine AMB, or behaviors that carry some risk. Gay and straight participants differed on the routine AMB they practiced. Men and women differed on the non-routine or risky AMB they practiced or would consider practicing. Implications are discussed and further research is suggested.

The Y chromosome gr/gr subdeletion is associated with male infertility

Men with Y chromosome (Yq) AZFc deletions lack all copies of the DAZ gene and have severe spermatogenic failure. A recently described gr/gr subdeletion of AZFc removes two of four copies of DAZ. To better understand the relative frequencies of AZFc and gr/gr deletions and their associated phenotypes, we analysed two large groups of infertile men. A total of 788 men from the Monash Male Infertility (MMI) database with a range of fertility disorders showed similar overall prevalences of AZFc (2.5%) and gr/gr deletions (3.4%). There was no association of gr/gr deletions with sperm density. In 234 control men of known or presumed fertility, only one gr/gr deletion was found. In a further 599 consecutive men presenting for assisted reproductive technologies, we detected 13 (2.2%) AZFc deletions and 28 (4.7%) gr/gr deletions. All AZFc deletions were seen with sperm densities <5 million/ml but again the gr/gr deletion occurred with similar frequency across all sperm density categories. These data show that gr/gr deletions are significantly associated with infertility in the Australian population (P = 0.0015) but not exclusively with reduced sperm density suggesting a complex interaction with other factors important for male fertility. Vertical transmission of gr/gr deletions from father to son by ICSI was demonstrated in four cases. Analysis of 130 ICSI-conceived sons revealed no de novo gr/gr deletions indicating that ICSI is not a risk factor. The data suggest that testing for gr/gr deletions should be considered in the routine genetic assessment of men with idiopathic infertility.

Investigation of chromosome 2q in osteoarthritis of the hand: no significant linkage in a Tasmanian population

BACKGROUND

Previous studies have suggested a strong genetic component to osteoarthritis (OA), especially that of the hand, and three linkage studies have suggested the existence of susceptibility loci in disparate regions of chromosome 2q.

OBJECTIVE

To examine for linkage to 2q in a Tasmanian population of women and men with familial hand OA.

METHODS

Hand OA (distal interphalangeal, carpometacarpal, and Heberden's nodes) was assessed by a combination of hand photographs and radiographs. A non-parametric linkage (NPL) analysis was performed on chromosome 2q of 69 members in 22 families with severe distal interphalangeal joint OA using Genehunter. A quantitative trait linkage analysis of a larger group of 456 members in 68 families was also performed using SOLAR.

RESULTS

The maximum non-parametric linkage score was 1.05 (p=0.15) at marker IL1R1, close to the centromere. All components of hand OA scores had significant heritability in this dataset (28%-35%, all p<0.001). Despite this, the quantitative trait analysis (after adjustment for age and, where appropriate, sex) yielded maximum LOD scores of 0.90 for Heberden's nodes (both sexes combined), and 1.19 for carpometacarpal OA score (women only).

CONCLUSIONS

These results do not provide confirmation of linkage on chromosome 2q in the larger white population with hand OA. They suggest that there are regional variations in the genetic cause of hand OA and that other loci not on 2q may be important in this disease.

Antibodies highly effective in SCID mice during infection by the intracellular bacterium Ehrlichia chaffeensis are of picomolar affinity and exhibit preferential epitope and isotype utilization

Although often considered to be ineffective against intracellular bacteria, Abs, in the absence of lymphocytes, have been shown previously to protect SCID mice from lethal infection by the obligate intracellular bacterium Ehrlichia chaffeensis, even when administered well after infection has been established. To identify characteristics of Abs that are critical for host defense during this intracellular infection, a panel of Ehrlichia-specific mAbs was generated and analyzed. Among 100 Abs recovered, 39 recognized an amino-terminal hypervariable region of an outer membrane protein (OMP), demonstrating that the OMPs are both antigenically variable and immunodominant. A subset of 16 representative OMP-specific Abs was further examined to identify characteristics that were essential for in vivo efficacy. The highly effective Abs recognized a linear epitope within the first hypervariable region of OMP-1g. Only IgG were found to be effective, and among the effective IgG, the following hierarchy was observed: IgG2a > IgG3 = IgG2b. The most striking characteristics of the highly effective Abs were their picomolar binding affinities and long binding t(1/2). Thus, although epitope recognition and isotype use may contribute to efficacy, high affinity may be a critical characteristic of Abs that can act effectively during this intracellular bacterial infection.

Evidence for functionally significant polymorphism of human glutamate cysteine ligase catalytic subunit: association with glutathione levels and drug resistance in the National Cancer Institute tumor cell line panel

Glutamate-cysteine ligase (GCL) is the first and rate-limiting enzyme involved in the biosynthesis of glutathione (GSH). The GCL heterodimer is encoded by two genes: GLCLC, which directs synthesis of the catalytic subunit, and GLCLR, which encodes the regulatory subunit. We have previously identified a polymorphic GAG/CTC trinucleotide repeat within the 5' untranslated region of GLCLC. Here we report the further characterization of GLCLC polymorphism and the existence of five GLCLC alleles as defined by the trinucleotide repeat, which exhibits a range of 4 to 10 uninterrupted repeats. Significant variation in GLCLC allele frequencies was observed in four different ethnic populations examined. Interindividual variation in the capacity to produce GSH due to GLCLC polymorphism is hypothesized to influence the cellular response to environmental toxicants and chemotherapeutic agents. To test this hypothesis, the 60 tumor cell lines of the National Cancer Institute drug screening panel were genotyped for the GLCLC trinucleotide repeat, and the association of GLCLC genotype with GSH levels and drug sensitivity/resistance data was examined. Here we demonstrate an association between certain GLCLC alleles and GSH levels and/or drug sensitivity, providing evidence that suggests polymorphism of human GLCLC is functionally significant.