The Immunology Quality Assessment Proficiency Testing Program for CD3⁺4⁺ and CD3⁺8⁺ lymphocyte subsets: a ten year review via longitudinal mixed effects modeling

Since 1999, the National Institute of Allergy and Infectious Diseases Division of AIDS (NIAID DAIDS) has funded the Immunology Quality Assessment (IQA) Program with the goal of assessing proficiency in basic lymphocyte subset immunophenotyping for each North American laboratory supporting the NIAID DAIDS HIV clinical trial networks. Further, the purpose of this program is to facilitate an increase in the consistency of interlaboratory T-cell subset measurement (CD3(+)4(+)/CD3(+)8(+) percentages and absolute counts) and likewise, a decrease in intralaboratory variability. IQA T-cell subset measurement proficiency testing was performed over a ten-year period (January 2003-July 2012), and the results were analyzed via longitudinal analysis using mixed effects models. The goal of this analysis was to describe how a typical laboratory (a statistical modeling construct) participating in the IQA Program performed over time. Specifically, these models were utilized to examine trends in interlaboratory agreement, as well as successful passing of proficiency testing. Intralaboratory variability (i.e., precision) was determined by the repeated measures variance, while fixed and random effects were taken into account for changes in interlaboratory agreement (i.e., accuracy) over time. A flow cytometer (single-platform technology, SPT) or a flow cytometer/hematology analyzer (dual-platform technology, DPT) was also examined as a factor for accuracy and precision. The principal finding of this analysis was a significant (p<0.001) increase in accuracy of T-cell subset measurements over time, regardless of technology type (SPT or DPT). Greater precision was found in SPT measurements of all T-cell subset measurements (p<0.001), as well as greater accuracy of SPT on CD3(+)4(+)% and CD3(+)8(+)% assessments (p<0.05 and p<0.001, respectively). However, the interlaboratory random effects variance in DPT results indicates that for some cases DPT can have increased accuracy compared to SPT. Overall, these findings demonstrate that proficiency in and among IQA laboratories have, in general, improved over time and that platform type differences in performance do exist.

Vomiting--is this a good indication for CT head scans in patients with minor head injury?

The National Institute for Health and Clinical Excellence head injury guidelines advise CT imaging within 1 h if there is more than one episode of vomiting post-head injury in adults and three or more episodes in children. Since the guideline publication, studies have found that, following head injury, vomiting alone is associated with an abnormal CT head scan in 13-45% of cases. CT head scan requests referred from the emergency department between 1 May 2009 and 30 April 2010 were retrospectively reviewed. Patients with vomiting as the sole indication for an "immediate" CT head scan performed within 1 h were included in the study. Reports produced by experienced neuroradiologists were reviewed and the detection of significant head injury was noted. There were 1264 CT head scans performed during our study period. 151 (124 adults, 27 children) were indicated owing to vomiting following head injury. 5 of the 124 adult scans and 1 of the 27 paediatric scans showed an abnormal finding, giving positive predictive values (PPV) of 4% and 3.7%, respectively. None of these patients required either acute or delayed neurosurgical intervention. In our experience, vomiting alone has a PPV of 4% for significant head injury in adults. However, none of these injuries were serious enough to warrant acute or delayed intervention. Given these findings, vomiting following head injury is a reasonable indication for a CT head scan; however, as none of the patients required acute intervention, we suggest that these scans do not usually need to be performed within 1 h of request.

Cone and rod photoreceptor transplantation in models of the childhood retinopathy Leber congenital amaurosis using flow-sorted Crx-positive donor cells

Retinal degenerative disease causing loss of photoreceptor cells is the leading cause of untreatable blindness in the developed world, with inherited degeneration affecting 1 in 3000 people. Visual acuity deteriorates rapidly once the cone photoreceptors die, as these cells provide daylight and colour vision. Here, in proof-of-principle experiments, we demonstrate the feasibility of cone photoreceptor transplantation into the wild-type and degenerating retina of two genetic models of Leber congenital amaurosis, the Crb1^rd8/rd8 and Gucy2e^−/− mouse. Crx-expressing cells were flow-sorted from the developing retina of CrxGFP transgenic mice and transplanted into adult recipient retinae; CrxGFP is a marker of cone and rod photoreceptor commitment. Only the embryonic-stage Crx-positive donor cells integrated within the outer nuclear layer of the recipient and differentiated into new cones, whereas postnatal cells generated a 10-fold higher number of rods compared with embryonic-stage donors. New cone photoreceptors displayed unambiguous morphological cone features and expressed mature cone markers. Importantly, we found that the adult environment influences the number of integrating cones and favours rod integration. New cones and rods were observed in ratios similar to that of the host retina (1:35) even when the transplanted population consisted primarily of cone precursors. Cone integration efficiency was highest in the cone-deficient Gucy2e^−/− retina suggesting that cone depletion creates a more optimal environment for cone transplantation. This is the first comprehensive study demonstrating the feasibility of cone transplantation into the adult retina. We conclude that flow-sorted embryonic-stage Crx-positive donor cells have the potential to replace lost cones, as well as rods, an important requirement for retinal disease therapy.

Assessment of magnification of digital pelvic radiographs in total hip arthroplasty using templating software

INTRODUCTION

Templating of pelvic radiographs traditionally involved using implant-company provided acetates which assumed a magnification of 115-120%. With the introduction of digital imaging, many departments are becoming filmless. Templating software has been designed to allow on-screen templating of digital images. Knowledge of the true magnification of the image is required for accurate measurement.

PATIENTS AND METHODS

Fifty consecutive postoperative pelvic radiographs were analysed using templating software. The implanted component was measured using an assumed magnification factor of 115%. The template image was then reset to the known component size, and the magnification factor was adjusted until the template covered the true component.

RESULTS

An assumed magnification factor of 115% oversized the acetabular component by a mean of 6 mm (three component sizes) in all 50 components. The mean true magnification in our department was 127%.

CONCLUSIONS

Validation of the true magnification produced by a radiology department using templating software is a simple and reproducible technique. It is recommended to all departments using digital images and templating software. Assumption of a magnification factor of 115% risks oversizing components by 6 mm.

Development of full-thickness macular hole despite previous posterior vitreous detachment and vitrectomy for retinal detachment: two cases

PURPOSE

To report the delayed development of idiopathic full-thickness macular hole in eyes with previously documented complete posterior vitreous detachment that were vitrectomized during surgery for rhegmatogenous retinal detachment.

METHODS

Two interventional case reports with serial color fundus photographs and optical coherence tomography scans.

RESULTS

Case 1: A 62-year-old man underwent vitrectomy, cryoretinopexy, and intraocular gas tamponade for rhegmatogenous retinal detachment associated with a complete posterior vitreous detachment. Three years later, he developed a full-thickness macular hole in the same eye. Peeling of the inner limiting membrane and gas tamponade resulted in complete closure of the macular hole with improvement in visual acuity. Case 2: A 70-year-old man presented with a macula-off inferior retinal detachment and counting fingers vision. Vitrectomy, cryoretinopexy to a single tear, and gas tamponade was successful and acuity improved to 6/9. He subsequently developed retinal redetachment associated with a new retinal tear and was treated by further vitrectomy and gas. He developed a full-thickness macular hole in the same eye 2 years later with acuity dropping to 1/60.

CONCLUSIONS

Macular hole formation may occur in the context of vitrectomized eyes. These observations support the hypothesis that anteroposterior vitreomacular traction, while traditionally implicated, is not always essential for the development of macular holes.

Multiple antigenic peptides facilitate generation of anti-prion antibodies

Recent reports have demonstrated the ability of anti-prion antibodies to inhibit PrPSc propagation. Due to the relatively poor immunogenic properties of both PrPC and PrPSc, the generation of anti-prion antibodies still causes a significant problem in the development of immunotherapeutic strategies. This study examines the potential of multiple antigenic peptides (MAPs) to raise an antibody response to prion derived sequences in mice. The MAP was constructed of a four spiked ring. Two spikes containing human or mouse derived prion amino acid sequences and two spikes containing the universally promiscuous tetanus toxoid sequence (aa 830-844) which was used to assist T-cell-dependent B-cell antibody production. Following vaccinations with the MAP or MAP plus adjuvant, sera were taken and antibody titres assessed. The MAP containing only the mouse sequence failed to elicit a significant antibody response. MAPs containing human prion sequences elicited antibody production to the corresponding prion sequence. Further analysis also demonstrated that these peptides were able to generate antibody responses that recognize conserved human and mouse sequences. These homologous sequences contain the heralded PrPSc specific sequence 'Tyr-Tyr-Arg' and therefore these MAPs may have some therapeutic potential.

Cell mediated immune responses against human prion protein

Vaccination approaches that may provide protection against the abnormal form of prion protein (PrPSc) have recently focused on the ability of antibodies to prevent PrPSc propagation. Progress has been hampered due to the difficulty in generating antibody responses in wild type mice, which is believed to be a consequence of T cell tolerance to the normal form of prion protein (PrPC). The problem of tolerance can be avoided using transgenic mice unable to express PrPC. This study examines active PrP specific T cell responses that can be produced in PrP null (PrP 0/0) mice using simple peptide vaccination procedures. Spleenocytes recovered from vaccinated PrP 0/0 mice were tested in vitro for their specificity with T cell recognition demonstrated through a proliferative response to the peptide. Analysis of mRNA also indicates the stimulation of a heterogenous population of T cells with an increase in cytokines and cytotoxicity associated mRNA. Responsive T cells were expanded using a T cell cloning procedure and demonstrated an ability to recognize the mature human prion protein. These clones may potentially be used to negate the problem of T cell tolerance in wild type mice.

An immune response after intraocular administration of an adenoviral vector containing a beta galactosidase reporter gene slows retinal degeneration in the rd mouse

BACKGROUND/AIMS

Retinal degenerations are a leading cause of blindness for which there are currently no effective treatments. This has stimulated interest in the investigation of gene therapy strategies for these diseases in a variety of animal models. A number of attempts have been made to prevent photoreceptor loss in the rd mouse model of retinal degeneration using adenoviral vectors containing either a copy of the missing functional gene or a gene encoding either a neurotrophic factor or an antiapoptotic factor. The authors have previously demonstrated that intraocular administration of an adenoviral vector containing a beta galactosidase gene (AV.LacZ) results in an immune response to viral gene products and beta galactosidase. Here the effect of the immune response on retinal degeneration is examined.

METHODS

Juvenile rd mice were injected intravitreally with AV.LacZ and a proportion were depleted of either CD4+ or CD8+ T cells or both. Control animals were injected with PBS. The mice were sacrificed 10 and 20 days post-injection and their eyes embedded in paraffin wax and sectioned.

RESULTS

10 days after intravitreal injection of AV.LacZ, the outer nuclear layer contains an average of 2.5 rows compared with 1.5 in PBS injected animals (p<0.005). The protective effect of AV.LacZ is negated by immune suppression and does not extend beyond 20 days.

CONCLUSION

An immune response to vector and transgene products is able to slow degeneration in the rd mouse. This phenomenon should be taken into account when analysing the degeneration in the rd mouse following gene transfer.

Some practical issues in the design, monitoring and analysis of a sequential randomized trial in pressure sore prevention

A sequential double blind (assessor and patient) triangular design was used to compare the incidence of pressure sores following elective major surgery among patients lying on a standard foam mattress with those on a dry visco-elastic polymer pad during their operation. A total of 446 patients were recruited into the trial between 1994 and 1996. Interim analyses were carried out after 181 patients were entered into the trial and then subsequently after approximately every 100 patients recruited. The trial unexpectedly reached a stopping boundary at the first interim analysis, however the Independent Data Monitoring Committee recommended continuation of the trial. They were concerned that there was a need for a larger definitive trial and about an apparent treatment by centre interaction. They required a substudy to be undertaken to further validate the subjective endpoint, and that further sensitivity analyses of the main trail endpoint should be carried out in the second interim analysis. The trial was stopped at the third interim analysis when again a stopping boundary was crossed indicating that the gel pad was associated with significantly fewer pressure sores than the standard mattress (log odds ratio -0.7, (95 per cent confidence interval (CI), -1.28, -0.11), p=0.02) (estimate CI, p-value adjusted for group sequential conduct). The design, monitoring and analysis of this trial will be presented as an example of the practical problems or non-problems encountered for the local hospitals, for the trials unit, for the data monitoring committee and for the funding committee.

Postoperative evaluation of patients following ophthalmic surgery

We have used telemedicine to support the postoperative evaluation of patients who have had ophthalmic surgery. Mobile telemedicine workstations connected using three ISDN lines have enabled us to review patients at an outreach clinic on the first postoperative day. Video slit-lamp images of the patient are captured by a trained ophthalmic nurse at the outreach clinic and viewed by surgeons at Moorfields Eye Hospital in central London during live teleconsultations. During the study period, over 80 teleconsultations were carried out on postoperative cataract, trabeculectomy and combined procedures. Preliminary results are very encouraging. Although 8 (33%) of 24 patients were anxious about being involved in the teleconsultation, 20 (83%) had confidence in the system and only one (4%) found the experience unacceptable.

Persistent expression of mitogenic/transforming factors at the site of failed orthopaedic implants: the impact on immune reactivity

The response to wear particles from orthopaedic implants can lead to inflammation, osteolytic lesions, and aseptic loosening. To gain an insight into the development of this pathogenetic process, immunohistochemical techniques were used to identify the expression and tissue distribution of the potent cell mitogen epidermal growth factor (EGF), and the epidermal growth factor receptor (EGF-R) at the site of bone erosion in 30 patients with clinically failed orthopaedic implants. The results showed a large proportion of the macrophage subsets (Mphi) which expressed EGF and EGF-R, also contained wear particles, indicating their expression is a consequence of Mphi phagocytosis of implant material. The surface membrane expression of EGF-R on fusing Mphi suggests its presence is fundamental to the formation of bone-resorbing multi-nucleated giant cells, and the development of osteolysis. Additionally, there is increasing evidence of the long-term systemic spread of wear particles and their accumulation at distal sites including lymph nodes, liver, and spleen. Elevated expression of mitogenic factors in response to wear particles may result in deviation from normal cell growth and regulation, resulting in changes to immune cell function. Such potential transformations at distal sites are clinically significant, as alterations to the patient's immune system may result in acute divergence from normal immune cell responses.

Care plan for documenting pharmacist activities

At a 393-bed hospital, a pharmaceutical care plan was developed and tested in a surgical intensive care unit (SICU). The trial care plan was developed and implemented with the following objectives: to integrate clinical and distributive elements of patient information in a care plan; to add new monitoring and intervention parameters to the pharmacy profile; and to assess and refine the care plan for implementation in other areas of the institution. One pharmacist performed and documented care for 10 patients in the SICU. The pharmacist planned appropriate drug administration schedules, noted appropriate indications for each medication ordered, established appropriate outcomes, monitored for drug-drug or drug-food interactions and allergies, recorded interventions and averted adverse drug reactions, and recorded the amount of time required for care according to disease state. Pharmacist involvement with medication administration and monitoring seemed to prevent many adverse effects and drug interactions. Because of the diversity of the patient population, there was substantial variation in the time spent on care. A trial pharmaceutical care plan in a surgical intensive care unit was useful for documenting pharmacists' productivity and effectiveness.

Pyrochlores. IV. Crystallographic and Mössbauer studies of A2FeSbO7 pyrochlores

The lattice parameters and the quadrupole splittings of the room-temperature Mössbauer spectra of the cubic A2FeSbO7 pyrochlores (A = Sm, Eu, Gd, Tb, Y, Er, Lu) have been found to vary linearly with the Templeton–Dauben radii of the A3+ ions. The variation of the quadrupole splitting can be correlated with the positional parameter of the majority oxygen atom, x(O2), which determines the degree of distortion of the BO6 octahedron in cubic A2B2O7 pyrochlores. An increase of 0.1 Å in r(A3+) corresponds to a decrease of ca. 0.20 mm/s in the quadrupole splitting in the A2FeSbO7 series, and to an estimated increase of ca. 0.005 in x(O2). The isomer shift and quadrupole splitting at room temperature are typical of Fe3+(high spin) in octahedral coordination of relatively high distortion. Y2FeSbO7 at 4.2°K was found to exhibit magnetic order with a hyperfine magnetic field of approximately 400 kOe. An attempt to prepare a cubic La2FeSbO7, pyrochlore by the standard procedure was not successful.