Massively parallel base editing screens to map variant effects on anti-tumor hallmarks of primary human T cells

Base editing enables generation of single nucleotide variants, but large-scale screening in primary human T cells is limited due to low editing efficiency, among other challenges 1 . Here, we developed a high-throughput approach for high-efficiency and massively parallel adenine and cytosine base-editor screening in primary human T cells. We performed multiple large-scale screens editing 102 genes with central functions in T cells and full-length tiling mutagenesis of selected genes, and read out variant effects on hallmarks of T cell anti-tumor immunity, including activation, proliferation, and cytokine production. We discovered a broad landscape of gain- and loss-of-function mutations, including in PIK3CD and its regulatory subunit encoded by PIK3R1, LCK , AKT1, CTLA-4 and JAK1 . We identified variants that affected several (e.g., PIK3CD C416R) or only selected (e.g. LCK Y505C) hallmarks of T cell activity, and functionally validated several hits by probing downstream signaling nodes and testing their impact on T cell polyfunctionality and proliferation. Using primary human T cells in which we engineered a T cell receptor (TCR) specific to a commonly presented tumor testis antigen as a model for cellular immunotherapy, we demonstrate that base edits identified in our screens can tune specific or broad T cell functions and ultimately improve tumor elimination while exerting minimal off-target activity. In summary, we present the first large-scale base editing screen in primary human T cells and provide a framework for scalable and targeted base editing at high efficiency. Coupled with multi-modal phenotypic mapping, we accurately nominate variants that produce a desirable T cell state and leverage these synthetic proteins to improve models of cellular cancer immunotherapies.

The CD58-CD2 axis is co-regulated with PD-L1 via CMTM6 and shapes anti-tumor immunity

The cell-autonomous balance of immune-inhibitory and -stimulatory signals is a critical process in cancer immune evasion. Using patient-derived co-cultures, humanized mouse models, and single-cell RNA-sequencing of patient melanomas biopsied before and on immune checkpoint blockade, we find that intact cancer cell-intrinsic expression of CD58 and ligation to CD2 is required for anti-tumor immunity and is predictive of treatment response. Defects in this axis promote immune evasion through diminished T cell activation, impaired intratumoral T cell infiltration and proliferation, and concurrently increased PD-L1 protein stabilization. Through CRISPR-Cas9 and proteomics screens, we identify and validate CMTM6 as critical for CD58 stability and upregulation of PD-L1 upon CD58 loss. Competition between CD58 and PD-L1 for CMTM6 binding determines their rate of endosomal recycling over lysosomal degradation. Overall, we describe an underappreciated yet critical axis of cancer immunity and provide a molecular basis for how cancer cells balance immune inhibitory and stimulatory cues.

Profiling Germinal Center-like B Cell Responses to Conjugate Vaccines Using Synthetic Immune Organoids

Glycoengineered bacteria have emerged as a cost-effective platform for rapid and controllable biosynthesis of designer conjugate vaccines. However, little is known about the engagement of such conjugates with naïve B cells to induce the formation of germinal centers (GC), a subanatomical microenvironment that converts naïve B cells into antibody-secreting plasma cells. Using a three-dimensional biomaterials-based B-cell follicular organoid system, we demonstrate that conjugates triggered robust expression of hallmark GC markers, B cell receptor clustering, intracellular signaling, and somatic hypermutation. These responses depended on the relative immunogenicity of the conjugate and correlated with the humoral response in vivo. The occurrence of these mechanisms was exploited for the discovery of high-affinity antibodies against components of the conjugate on a time scale that was significantly shorter than for typical animal immunization-based workflows. Collectively, these findings highlight the potential of synthetic organoids for rapidly predicting conjugate vaccine efficacy as well as expediting antigen-specific antibody discovery.

Combinatorial treatment rescues tumour-microenvironment-mediated attenuation of MALT1 inhibitors in B-cell lymphomas

Activated B-cell-like diffuse large B-cell lymphomas (ABC-DLBCLs) are characterized by constitutive activation of nuclear factor κB driven by the B-cell receptor (BCR) and Toll-like receptor (TLR) pathways. However, BCR-pathway-targeted therapies have limited impact on DLBCLs. Here we used >1,100 DLBCL patient samples to determine immune and extracellular matrix cues in the lymphoid tumour microenvironment (Ly-TME) and built representative synthetic-hydrogel-based B-cell-lymphoma organoids accordingly. We demonstrate that Ly-TME cellular and biophysical factors amplify the BCR-MYD88-TLR9 multiprotein supercomplex and induce cooperative signalling pathways in ABC-DLBCL cells, which reduce the efficacy of compounds targeting the BCR pathway members Bruton tyrosine kinase and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1). Combinatorial inhibition of multiple aberrant signalling pathways induced higher antitumour efficacy in lymphoid organoids and implanted ABC-DLBCL patient tumours in vivo. Our studies define the complex crosstalk between malignant ABC-DLBCL cells and Ly-TME, and provide rational combinatorial therapies that rescue Ly-TME-mediated attenuation of treatment response to MALT1 inhibitors.

Dissecting the treatment-naive ecosystem of human melanoma brain metastasis

Melanoma brain metastasis (MBM) frequently occurs in patients with advanced melanoma; yet, our understanding of the underlying salient biology is rudimentary. Here, we performed single-cell/nucleus RNA-seq in 22 treatment-naive MBMs and 10 extracranial melanoma metastases (ECMs) and matched spatial single-cell transcriptomics and T cell receptor (TCR)-seq. Cancer cells from MBM were more chromosomally unstable, adopted a neuronal-like cell state, and enriched for spatially variably expressed metabolic pathways. Key observations were validated in independent patient cohorts, patient-derived MBM/ECM xenograft models, RNA/ATAC-seq, proteomics, and multiplexed imaging. Integrated spatial analyses revealed distinct geography of putative cancer immune evasion and evidence for more abundant intra-tumoral B to plasma cell differentiation in lymphoid aggregates in MBM. MBM harbored larger fractions of monocyte-derived macrophages and dysfunctional TOX+CD8+ T cells with distinct expression of immune checkpoints. This work provides comprehensive insights into MBM biology and serves as a foundational resource for further discovery and therapeutic exploration.

Multiscale engineering of immune cells and lymphoid organs

Immunoengineering applies quantitative and materials-based approaches for the investigation of the immune system and for the development of therapeutic solutions for various diseases, such as infection, cancer, inflammatory diseases and age-related malfunctions. The design of immunomodulatory and cell therapies requires the precise understanding of immune cell formation and activation in primary, secondary and ectopic tertiary immune organs. However, the study of the immune system has long been limited to in vivo approaches, which often do not allow multidimensional control of intracellular and extracellular processes, and to 2D in vitro models, which lack physiological relevance. 3D models built with synthetic and natural materials enable the structural and functional recreation of immune tissues. These models are being explored for the investigation of immune function and dysfunction at the cell, tissue and organ levels. In this Review, we discuss 2D and 3D approaches for the engineering of primary, secondary and tertiary immune structures at multiple scales. We highlight important insights gained using these models and examine multiscale engineering strategies for the design and development of immunotherapies. Finally, dynamic 4D materials are investigated for their potential to provide stimuli-dependent and context-dependent scaffolds for the generation of immune organ models.

Ex vivo synthetic immune tissues with T cell signals for differentiating antigen-specific, high affinity germinal center B cells

Most antigen discovery and vaccine development aimed at driving functional B cell responses rely on mouse immunizations studies. To date, there is no 3D ex vivo immune tissues, which are capable of driving antigen-specific B cell responses to rapidly determine the humoral immunogenicity of antigens, understand the role of extracellular matrix in humoral immunity, and generate high affinity antibody responses. This can be attributed to the complexity of B cell differentiation and affinity maturation process in the germinal center (GC) reaction, which makes these highly specialized cells susceptible to rapid apoptosis ex vivo. We have previously reported immune tissues that show ex vivo GC-like response, however in a non-antigen specific manner. Here, we report a maleimide (MAL)-functionalized polyethylene glycol (PEG)-based designer immune tissues that modulate B cell differentiation and enriches antigen-specific GC B cells in the presence of T-cell like signals. With the 3D synthetic immune tissue platform, we assessed various hydrogel design parameters to control ex vivo GC reaction. Using an Ezh2fl/fl Cγ1-cre transgenic mouse model, we demonstrated ex vivo IgG1 antibody class switching. Using immune tissues developed from a B1-8hi mutant mouse that represents a recombined antibody variable region derived from a 4-hydroxy-3-nitrophenylacetyl (NP) hapten binding antibody (B1-8), we demonstrate antigen specificity and selective enrichment of antigen-specific B cells with high affinity at both cell surface and secreted levels in integrin ligand-dependent manner. The ex vivo antigen-specific platform technology offers use in scientific understanding of immunobiology, matrix immunology, and in biotechnology applications, ranging from the antigen testing, vaccine development, and generation of antibodies against diseases.

Integrating perioperative medicine with anaesthesia in India: Can the best be achieved? A review

Integrating perioperative medicine with anaesthesia is the need of the hour. Evolution of a new superspeciality called perioperative anaesthesia can improve surgical outcomes by quality perioperative care and guarantee imminent escalation of influence and power for anaesthesiologists. All original peer-reviewed manuscripts pertaining to surgery-specific perioperative surgical home models involving preoperative, intraoperative and postoperative initiatives spanning the past 5 years have been reviewed using PubMed and Google Scholar. Whether the perioperative surgical home model is feasible or still a distant dream in the Indian perspective has been analysed.

Saline conditions alter morpho-physiological intensification in purslane (Portulaca oleracea l.)

In this study, primary investigations of selected cultivar of purslane named as Tall Green under articular salinity stress were evaluated to understand the basic concept of different mechanisms of physiological attributes which will play an important role for molecular and proteomic level research. The evaluation of morphological and physiological attributes under 0 mM (without salt addition) 100 mM and 200 mM salt stress changed dramatically. The results showed high salt stress at 200 mM significantly decreasing the morphological attributes and performance of leaves, stems, and roots. At moderate salt stress levels, 100 mM, the ratio of Fv/Fm slightly increased compared to high stress. In addition, salt stress significantly decreased the total chlorophyll content (chl a+b) at 200 mM. The relative water content percentage was high at 0 mM. Moreover, the electrolyte leakage (EL) significantly increased with increasing salinity stress compared to control 0 mM.

Creating artificial lymphoid tissues to study immunity and hematological malignancies

PURPOSE OF REVIEW

The specialized microenvironments of lymphoid tissue affect immune cell function and progression of disease. However, current animal models are low throughput and a large number of human diseases are difficult to model in animals. Animal models are less amenable to manipulation of tissue niche components, signalling pathways, epigenetics, and genome editing than ex vivo models. On the other hand, conventional 2D cultures lack the physiological relevance to study precise microenvironmental interactions. Thus, artificial tissues are being developed to study these interactions in the context of immune development, function, and disease.

RECENT FINDINGS

New bone marrow and lymph node models have been created to, respectively, study microenvironmental interactions in hematopoiesis and germinal center-like biology. These models have also been extended to understand the effect of these interactions on the progression and therapeutic response in leukemia, multiple myeloma, and lymphoma.

SUMMARY

3D in-vitro immune models have elucidated new cellular, biochemical, and biophysical interactions as potential regulatory mechanisms, therapeutic targets, or biomarkers that previously could not be studied in animal models and conventional 2D cultures. Incorporation of advanced biomaterials, microfluidics, genome editing, and single-cell analysis tools will enable further studies of function, driver mutations, and tumor heterogeneity. Continual refinement will help inform the development of antibody and cell-based immunotherapeutics and patient-specific treatment plans.

A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering

In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom-up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N-isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm-PDMS substrates optimal for VSMC attachment. To allow long-term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm-PDMS surfaces were further modified with 3-aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single-layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single-layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.

Cellular self-assembly and biomaterials-based organoid models of development and diseases

Organogenesis and morphogenesis have informed our understanding of physiology, pathophysiology, and avenues to create new curative and regenerative therapies. Thus far, this understanding has been hindered by the lack of a physiologically relevant yet accessible model that affords biological control. Recently, three-dimensional ex vivo cellular cultures created through cellular self-assembly under natural extracellular matrix cues or through biomaterial-based directed assembly have been shown to physically resemble and recapture some functionality of target organs. These "organoids" have garnered momentum for their applications in modeling human development and disease, drug screening, and future therapy design or even organ replacement. This review first discusses the self-organizing organoids as materials with emergent properties and their advantages and limitations. We subsequently describe biomaterials-based strategies used to afford more control of the organoid's microenvironment and ensuing cellular composition and organization. In this review, we also offer our perspective on how multifunctional biomaterials with precise spatial and temporal control could ultimately bridge the gap between in vitro organoid platforms and their in vivo counterparts.

STATEMENT OF SIGNIFICANCE

Several notable reviews have highlighted PSC-derived organoids and 3D aggregates, including embryoid bodies, from a development and cellular assembly perspective. The focus of this review is to highlight the materials-based approaches that cells, including PSCs and others, adopt for self-assembly and the controlled development of complex tissues, such as that of the brain, gut, and immune system.

Modular Immune Organoids with Integrin Ligand Specificity Differentially Regulate Ex Vivo B Cell Activation

Germinal centers are dynamic structures within lymphoid tissues, which develop once B cells receive activating signals from surrounding immune cells. Germinal center B cells are small in number, heterogeneous, and prone to rapid apoptosis unless selected by the body to form memory B cells. Despite extensive research in the B cell differentiation process, the role of the lymphoid niche, in particular integrin ligands, in the development of early germinal center-like phenotype remains unclear. Here, we report a biomaterials-based modular immune organoid that enables development of early germinal-center phenotype in an integrin ligand-specific manner. We demonstrate the differential role of integrin α4β1- and αvβ3-binding ligands in the induction of GL7+ (GC-like) and GL7- (non-GC-like) phenotype in differentiating B cells while in the presence of CD40 ligand and interleukin-4. We further demonstrate the role of integrin ligand specificities in clustering of β3 integrin and B cell receptor on the surface of differentiated B cells in 3D organoids as compared to the classic 2D cocultures. The study demonstrates that biomaterials-based immune organoids represent an ex vivo platform technology, which recapitulates certain aspects of GC biology to understand the process of B cell differentiation and induction of immunological responses. This platform is particularly useful in understanding the role of selective biomolecular signals and the temporal dependency of immune responses to these signals.

Ceric-induced grafting of acrylonitrile onto sodium alginate: kinetics and mechanism and effects of the reaction medium

The kinetic scheme of free radical graft copolymerization of acrylonitrile (AN) onto sodium alginate, using ceric ammonium nitrate as an initiator, has been proposed and equations relating the values of Rp, Rr and Rh are also suggested. The results have been found to be in good agreement with the proposed mechanism. The per cent grafting of AN onto sodium alginate has also been determined as a function of composition of the mixed solvents comprising methanol: water, ethanol: water, n-propanol:water and n-butanol: water systems. The reaction medium has been found to play an important role in graft copolymerization. The results of the effect of the reaction medium on grafting are also discussed.

Outcome of treatment of nonunion tibial shaft fracture by intramedullary interlocking nail augmentated with autogenous cancellous bone graft

To assess results of operative treatment of non union fracture shaft of Tibia by intramedullary interlocking nail augmented with autogenous cancellous bone graft in our setup. A total of 25 nonunion tibial shaft fractures were evaluated among which 20 cases were male and 5 female with the mean age 31.84 years. Hypertrophic non-union were 14 and atrophic non union were 11. Upper one third of tibial diaphysis was involved in 4 cases, middle one third in 14 cases and lower one third in 7 cases. In all cases open reduction, interlocking nailing and autogenous cancellous bone graft was applied. The mean follow up was one year. Mean time for healing was 8.08 months. Mean operation time was 110 minutes (range 70 to 160 minutes). Satisfactory results (excellent and good) were achieved in 88% cases and unsatisfactory (fair and poor) results in 12% cases. This operative treatment option appears to have a high success rate and should be considered in nonunion of tibial diaphysis.

Outcome of Minimal Invasive Percutaneous Plate Osteosynthesis in closed fractures of distal tibia

Background: The limited soft tissue, subcutaneous location and poor vascularity render the dista tibial fractures very challenging. Treatment of distal tibial fractures using minimally invasive percutaneous plate osteosynthesis technique may minimise damage to soft tissues and vascular integrity of bony fragments, leaving comminuted fragments out of the mechanical construct, preserving soft tissues with limited operative exposure. Objective: To assess the outcome of patients treated with minimally invasive percutaneous plate osteosynthesis technique for closed distal tibial fractures. Methods: The study included total of 30 patients (24males and 6females) with close distal tibia fracture, which were treated with distal tibia locking plate using minimally invasive percutaneous plate osteosynthesis technique. Results: The mean ages of the patient were 44.23 years (30 to58 years). Patients were followed up at 2 weeks, 6weeks, 12weeks, 24weeks and 1 year after the operation and evaluated clinically and radiologically. Among 30 pateints, all fractures went to union. The mean American orthopaedic foot and ankle score was 89.23% (SD-3.92). There was 2case of superficial infection and 3 case of plate impingement with no intraoperative complication and mortality rates. Conclusion: Minimally invasive percutaneous plate osteosynthesis is an effective technique for the management of distal tibial fractures. It is minimally invasive, though technically demanding, but preserves the biological environment by preserving the soft tissue with better outcome in terms of radiological union and functional outcome. Journal of College of Medical Sciences-Nepal, 2013, Vol-9, No-2, 38-44 DOI: http://dx.doi.org/10.3126/jcmsn.v9i2.9686

Diaphyseal femoral fractures in children treated with titanium elastic nail system

Femur fractures are common long bone injuries in children which account for less than 2% of all paediatric fractures. Although these fractures are dramatic and disabling injuries for the child and parent, the good part is that they unite rapidly with minimal complications if aligned well. Various methods have been used successfully to treat these fractures, but they differ in their stability and potential for complications. The aim of our study was to see the outcome of titanium elastic nailing system in diaphyseal femoral fracture in children. The study included total of 30 children's (19 boys and 11 girls) of diaphyseal femoral fracture treated with titanium elastic nailing system and they were followed up at 2, 6, 12 and 24 weeks. The average duration of callus formation was 3.5 weeks with radiological union mean time of 9.5 weeks. Full weight bearing was possible in a mean time of 10 weeks. According to flynn's scoring criteria, excellent and good results were in 24 cases (80%) and 6 cases (20%) respectively. The nail irritation was present in 3 childrens and there was no post operative infection, physeal injury and implant failure. Titanium elastic nail is a safe and satisfactory mode of treatment and is relatively easy to perform in disphyseal fracture of femur in children. It avoids the chances of physeal injury, infection and offers rapid healing.

The treatment of trigger thumb in children: conservative or surgical?

The trigger thumb is an uncommon condition in infants and children which occurs due to pathology of flexor pollicis longus or A1 pulley. The objectives in our study were to determine the treatment outcome of trigger thumb. The study included total of 45 patients (24 males and 21 females) with trigger thumb. The mean age of onset was 28.5 months (3 months -7 years). There was overall success rate of 72.41% following conservative treatment and the success rate appears to be higher in the younger age group. The outcome of children who underwent surgery was 91.66% with recurrence rate of 8.33% and superficial wound infection rate of 4.16%. Our study suggests that surgery is not urgent, postponing surgery does not interfere with the result, trying conservative methods to get a higher chance of recovery is reasonable before the elective surgery. So conservative approach should be adopted in treating trigger thumb.

Comparative study in surgical outcome of intracapsular fracture neck of femur in active elderly patients treated with hemiarthroplasty with Austin Moore's and bipolar prosthesis

Fracture neck of femur is most commonly encountered fractures in elderly population. Hemiarthroplasty is generally considered to be the treatment of choice in most active elderly patients. However, there is inadequate evidence to support the choice between unipolar or bipolar prosthesis. This study was conducted to analyze the outcome regarding pain, hip function, complication and acetabular erosion in patients randomly selected and treated with Austin Moore's or Bipolar hemiarthroplasty in our setup. The study included total of 40 patients (17 males and 23 females) with intracapsular neck of femur fractures with mean age of 67 years (55-85 years). 20 patients each were treated with Hemiarthroplasty using Austin Moore's and Bipolar prosthesis. The patients were followed up at intervals of 2 weeks, 6 weeks, 24 weeks and 1 year after the operation and evaluated clinically and radiologically. There were no significant differences between the groups regarding complication. The Harris hip score were 81.95% (SD - 2.99) in Austin Moore's hemiarthroplasty and 79.15% (SD - 2.94) in Bipolar hemiarthroplasty (p = 0.812), whereas acetabular erosion was 20.05% in Austin Moore's hemiarthroplasty and 5% in Bipolar hemiarthroplasty (p = 0.758) with no mortality seen during lyear follow up. The intracapsular neck of femur fracture in active elderly patients treated with Austin Moore's hemiarthroplasty had better outcome regarding pain and hip function whereas high acetabular erosion compared to patients treated with Bipolar hemiarthroplasty though the difference is statistically insignificant.

Outcome of pertrochantric fracture of the femur treated with proximal femoral locking compression plate

Pertrochantric femoral fractures are one of the most common fracture in old patients with variety of complications. However fixing Pertrochantric femoral fractures properly is clinically challenging. We report the outcome of pertrochantric femoral fractures treated with Proximal Femoral Locking Compression Plate (PFLCP) using Minimal Invasive Percutaneous Plate Osteosynthesis (MIPPO) techniques which were evaluated clinically by Harris hip score and radiologically for a union at fracture site and implant related complication. The study included total of 33 patients (20 males and 13 females) with Pertrochantric femoral fractures. The mean ages of the patients were 57 years (23-88 years). Pertrochantric femoral fractures included both Intertrochantric and Subtrochantric femoral fractures. Patients were followed up at 2 weeks, 6 weeks, 3 months, 6 months and 1 year after the operation. Among the 33 patients, the union rate was 95% (31 patients). However there were 1 case of implant breakage and 1 case of non union. According to Harris Hip score the excellent and good results were 87.87% with no mortality during 1 year follow up period. The PFLCP can be feasible alternative to the treatment of Pertrochantric femoral fractures by providing biological healing and mechanical stability with limited occurrence of complications.

Staple versus locking compression plate fixation after lateral closing wedge high tibial osteotomy

PURPOSE

To compare the results of staple versus locking compression plate fixation after closing wedge high tibial osteotomy.

METHODS

A group of 23 patients (24 knees) who underwent box high tibial osteotomy and staple fixation was compared with another group of 19 patients (22 knees) who underwent a similar procedure but with locking compression plate fixation. Both groups were followed up for 3 years. The range of movement, Hospital for Special Surgery (HSS) Knee Score, time to full weight bearing, incidence of delayed union, femorotibial angle, and stage of osteoarthritis were compared.

RESULTS

At 6 months after the operation, the median HSS score and the proportion of patients with excellent or good scores were significantly higher in the locking compression plate than the staple fixation group (76 vs 62, p=0.003; 75% vs 42%, p=0.0354), but not at one and 3 years. The range of movement was significantly greater in the locking compression plate fixation group in the short term (6 weeks, 3 and 6 months), but not after one year. The median time to full weight bearing was significantly shorter in the locking compression plate fixation group (86 vs 116 days, p<0.001). There were fewer delayed unions in the locking compression plate fixation group but not significantly (1 vs 5, p=0.198), possibly because of the small numbers involved. There was no difference, within the limits of measurement error, in the femorotibial angle or correction loss between the 2 groups.

CONCLUSION

Locking compression plate fixation obviates the use of plaster casts, enables early mobilisation and bone union, and reduces the numbers with delayed union and the time to full weight bearing. Longer-term studies are needed to evaluate its effect on revarisation and arthropathy.

In vivo expression of myosin essential light chain using plasmid expression vectors in regenerating frog skeletal muscle

It is well established that mutations in specific structural elements of the motor protein myosin are directly linked to debilitating diseases involving malfunctioning striated muscle cells. A potential way to study the relationship between myosin structure and function is to express exogenous myosin in vivo and determine contractile properties of the transgenic muscle cells. However, in vivo expression of functional levels of contractile proteins using transient transgenesis in skeletal muscle has not been demonstrated. Presently, we used in vivo gene transfer to express high levels of full-length myosin light chain (MLC) in skeletal muscle fibers of Rana pipiens. Anterior tibialis (AT) muscles were injected with cardiotoxin to cause degeneration and then injected at various stages of regeneration with plasmid expression vectors encoding full-length MLC1(f). In fibers from the most robustly transfected muscles 3 weeks after plasmid injections, trans-MLC1(f) expression averaged 22-43% of the endogenous MLC1(f). Trans-MLC1(f) expression was the same whether a small epitope tag was placed on the C- or N-terminus and was highly variable along individual fibers. Confocal microscopy of skinned fibers showed correct sarcomeric incorporation of trans-MLC1(f). The expression profile of myosin heavy chain isoforms 21 days after transfection was similar to normal AT muscle. These data demonstrate the feasibility of using in vivo gene transfer to probe the structural basis of contractile protein function in skeletal muscle. Based on these promising results, we discuss how further improvements in the level and consistency of myosin transgene expression may be achieved in future studies, and the therapeutic potential of plasmid gene transfer in regenerating muscle.

Bench-scale biofilter for removing ammonia from poultry house exhaust

A bench-scale biofilter was evaluated for removing ammonia (NH3) from poultry house exhaust. The biofilter system was equipped with a compost filter to remove NH3 and calcium oxide (CaO) filter to remove carbon dioxide (CO2). Removal of NH3 and CO2 from poultry house exhaust could allow treated air with residual heat to be recirculated back into the poultry house to conserve energy during winter months. Apart from its use as a plant nutrient, NH3 removal from poultry house exhaust could lessen the adverse environmental impacts of NH3 emissions. Ammonia and CO2 were measured daily with gas detector tubes while temperatures in the poultry pen and compost filter were monitored to evaluate the thermal impact of the biofilter on treated air. During the first 37 days of the 54-day study, exhaust air from 33 birds housed in a pen was treated in the biofilter; for the final 17 days, NH3-laden exhaust, obtained by applying urea to the empty pen was treated in the biofilter. The biofilter system provided near-complete attenuation of a maximum short-term NH3 concentration of 73 ppm. During the last 17 days, with a mean influent NH3 concentration of 26 ppm, the biofilter provided 97% attenuation. The CaO filter was effective in attenuating CO2. Compared with a biofilter sized only for NH3 removal, an oversized biofilter would be required to provide supplemental heat to the treated air through exothermic biochemical reactions in the compost. The biofilter could conserve energy in poultry production and capture NH3 for use as plant nutrient. Based on this study, a house for 27,000 broilers would require a compost filter with a volume of approximately 34 m3.

Sarcomere number regulation maintained after immobilization in desmin-null mouse skeletal muscle

The serial sarcomere number of skeletal muscle changes in response to chronic length perturbation. The role of the intermediate filament desmin in regulating these changes was investigated by comparing the architectural adaptations of the tibialis anterior, extensor digitorum longus (EDL) and soleus from wild-type mice with those of homozygous desmin knockout mice after hindlimb immobilization. After 28 days, serial sarcomere number increased significantly in the lengthened wild-type tibialis anterior (by approximately 9 %) and EDL (by approximately 17 %). Surprisingly, muscles from desmin knockout mice also experienced significant serial remodeling, with the serial sarcomere number of the tibialis anterior increasing by approximately 10 % and that of the EDL by approximately 27 %. A consistent result was observed in the shortened soleus: a significant decrease in sarcomere number was observed in the muscles from both wild-type (approximately 26 %) and knockout (approximately 12 %) mice. Thus, although desmin is not essential for sarcomerogenesis or sarcomere subtraction in mouse hindlimb muscles, the results do suggest subtle differences in the nature of sarcomere number adaptation. We speculate that desmin may play a role in regulating the optimal arrangement of sarcomeres within the muscle or in sensing the magnitude of the immobilization effect itself.

Chronic rhinosinusitis: allergy and sinus computed tomography relationships

The management of chronic or recurrent rhinosinusitis problems is multifaceted and should include consideration of contributory and potentially correctable medical and anatomic factors. To date, the relationship between allergy and rhinosinusitis has not been clearly defined. The purpose of this study is to improve understanding of the relative roles of perennial and seasonal allergens in the cause of chronic rhinosinusitis. A retrospective review of 200 consecutive patients was carried out on patients who had chronic rhinosinusitis refractory to medical therapy and who subsequently underwent functional endoscopic sinus surgery. All of these patients had allergy testing for common perennial and seasonal inhalant allergens before surgery. Each patient had sinus CT imaging before undergoing the surgery. The CT scans of each patient were staged according to a validated, standardized grading system by investigators blinded to allergic profile. Allergy testing indicated that 84% of all patients tested positive for allergies. Moreover, 60% of all patients had significant allergic sensitivity; 52% of all patients had multiple allergen sensitivities. Furthermore, there was a predominance of perennial allergens, especially house dust mite over seasonal allergens. The vast majority of our patients undergoing functional endoscopic sinus surgery had concomitant allergy. This study highlights the potential contribution of perennial allergies to the development of rhinosinusitis. Given this direction, future studies may reveal that in the care of patients with perennial allergic rhinitis, early intervention with identification of the offending allergen(s), and subsequent treatment through avoidance, pharmacotherapy, and/or immunotherapy may help in the prevention of recurrent and chronic rhinosinusitis.

Laser in situ keratomileusis to correct residual myopia and astigmatism after radial keratotomy

PURPOSE

To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) in selected post-radial-keratotomy (RK) eyes with residual myopia and astigmatism.

SETTING

TLC-The Brea Laser Eye Center, Brea, California, USA.

METHODS

Nine eyes of 6 patients who had had RK but had residual myopia and/or astigmatism had LASIK. All RK eyes had 8 radial incisions, were more than 1 year post-RK, had no epithelial inclusion cysts or corneal disease, and had had no subsequent ocular surgery. Follow-up was a minimum of 13 months, at which time uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, cycloplegic refraction, keratometry, central and peripheral pachymetries, intraocular pressure, and a subjective assessment of visual function were obtained.

RESULTS

At the last follow-up, the mean spherical equivalent (SE) was -0.156 diopter (D) +/- 0.174 (SD). All eyes treated for distance vision had a UCVA of 20/25 or better. No patient lost BCVA. No intraoperative or postoperative complications occurred. Seven eyes had morning and evening measurements. The mean change in manifest SE from morning to evening was -0.143 D. Six of the 7 eyes (86%) had 0 to 1 Snellen line change in UCVA from morning to evening. The subjective questionnaire revealed a high degree of satisfaction with overall vision, minimal glare, and less fluctuation in daily vision than before LASIK.

CONCLUSION

Laser in situ keratomileusis is safe and efficacious for reducing residual myopia and astigmatism in properly selected RK patients.

Nontraumatic nasal septal abscesses in the immunocompromised: etiology, recognition, treatment, and sequelae

Proper management of a nasal septal abscess requires prompt diagnosis, adequate surgical drainage, and antibiotics to prevent the potentially dangerous spread of infection and the development of severe functional and cosmetic sequelae. Most septal abscesses are the result of trauma to the nose with septal hematoma and subsequent infection. We present our experience with nasal septal abscesses in five immunocompromised patients without history of nasal trauma. All patients were treated with surgical drainage and antibiotics. The infections in four patients resolved, whereas in the fifth, the infection led to death. We report these cases to depict alternate etiologies of nasal septal abscess, particularly in the immunocompromised patient. Our review illustrates the wide spectrum of disease presentation, provides treatment strategies, and emphasizes the potentially catastrophic sequelae of this disease when unrecognized. With the growing number of immunocompromised individuals, it is important to recognize the potential for immunocompromise to influence the development of septal abscess.

Transmucosal fine-needle aspiration diagnosis of intraoral and intrapharyngeal lesions

OBJECTIVES

The effectiveness of fine-needle aspiration biopsy (FNAB) for the diagnosis of neck, thyroid, and salivary gland masses is well documented. Very few reports explore the potential of an intraoral FNAB approach for the diagnosis of submucosal lesions. We describe our technique and present case examples of pertinent differential diagnostic entities. We recommend an expanded role for FNAB of the oral cavity and oropharynx.

STUDY DESIGN

Retrospective review.

METHODS

A uniform technique was employed for transmucosal FNAB of 76 patients with intraoral masses. In applicable cases, cytology results were compared with traditional biopsy methods and permanent histopathologic specimens for accuracy.

RESULTS

Our experience demonstrates the high sensitivity (93%) and specificity (86%) of intraoral FNAB when compared with biopsy by conventional means. FNAB provides distinct advantages for the cytologic diagnosis of submucosal lesions, which may be difficult to reach and adequately sample through conventional biopsy. FNAB of the tonsil and tonsillar fossa provides a safe and effective means of diagnosing both lymphoma and squamous cell cancer. Transmucosal FNAB via the mouth led to rapid diagnosis of a number of benign and malignant lesions. Applying this uniform FNAB technique, we had no significant complications.

CONCLUSION

We recommend transmucosal FNAB as an effective means for highly accurate diagnosis of submucosal lesions of the oral cavity and oropharynx.

CLINICAL RELEVANCE

Traditional biopsy techniques in the oral cavity may require anesthesia and may have diagnostic difficulties, particularly for submucosal lesions. Transmucosal FNAB overcomes these shortcomings by providing a minimally invasive means to rapid diagnosis of intraoral lesions.

Transverse/sigmoid sinus dural arteriovenous fistulas presenting as pulsatile tinnitus

OBJECTIVE/HYPOTHESIS

Transverse/sigmoid sinus dural arteriovenous fistula (TSDAVF) is a diagnostically elusive entity that is critical for the otologist to account for, when confronted by pulsatile tinnitus in the face of normal otoscopy. Left untreated, TSDAVF may result in catastrophic outcome. We have previously proposed a grading system specifically for TSDAVF based on venous restrictive disease. Our objective was to assess the validity of this grading system for clinical severity and therapeutic outcome.

METHODS

Through a retrospective review of 41 patients with TSDAVF, we evaluated clinical presentation, diagnostic evaluation, therapy, and outcome. Patients were classified into four grades based on the severity of venous restrictive disease as determined by superselective angiography. Our treatment algorithm combined compression therapy, transarterial embolization, and for more severe grades, surgery.

RESULTS

Pulsatile tinnitus was the chief complaint of all the patients in this series, and of 90% of all cases of TSDAVF treated at our institution. While angiography remains the gold standard, magnetic resonance imaging/magnetic resonance arteriography is far superior to computed tomography scanning in detecting dural arteriovenous fistulas. As normal venous outflow gives way to aberrant cortical venous drainage in higher grades, there is a dramatically increased risk for adverse consequences with therapeutic intervention. Using our treatment algorithm, 82% of patients achieved clinical resolution of symptoms. Half of these patients had complete angiographic obliteration of their TSDAVF.

CONCLUSIONS

The TSDAVF-specific grading system for the severity of venous restrictive disease is reflective of clinical presentation, fundamental in planning treatment, and predictive of therapeutic outcome.

Facial nerve surgery in the 19th and early 20th centuries: The evolution from crossover anastomosis to direct nerve repair

The historical aspects of facial nerve (FN) anatomy and of Bell's palsy have long been favorite topics of otologic historians. Little attention has been paid, however, to the evolution of FN surgery, a subject with a remarkably rich and engaging history. In the early 13th century, Roland, an Italian surgeon, used a red hot iron to coapt severed nerve endings. In the 17th century, Ferrara, another Italian, sutured injured nerves with tortoise tendon dipped in hot red wine. It was not until the late 19th century that peripheral nerve suture became a subject of serious scientific study. Although it is ironic, the course of events suggests that the evolution of FN repair was greatly stimulated by the development of the modern mastoid operation. Whereas the simple mastoid operation practiced by Wilde (1853) and others carried little risk of FN injury, more adventuresome procedures such as radical mastoidectomy (Kessel, 1885) carried a much greater risk. The abundance of iatrogenic palsies during this era undoubtedly did much to motivate surgeons to seek a better means of restoring facial animation. Most surgeons would be surprised to learn that crossover anastomoses predated direct nerve repair by nearly half a century. In 1879, the German surgeon Drobnik performed the first facial-spinal accessory anastomosis. Over the next two decades, numerous articles were written (most notably by Sir Charles Balance and Harvey Cushing) on crossovers between the FN and cranial nerves IX, X, XI, and XII. Although a few tentative attempts at reapproximating severed FNs took place in the first two decades of this century, it was not until 1925 that an actual suture repair of an intratemporal injury was undertaken. This feat was first accomplished by the famous hand surgeon Sterling Bunnell and shortly thereafter by the otolaryngologist Robert Martin. The evolution of FN surgery in the days predating the operating microscope is a rich tapestry of colorful personalities and clashing egos, which saw promising advances relegated to obscurity and some previously obscure techniques become progressively more promising.

Perioperative management of von Willebrand's disease in otolaryngologic surgery

von Willebrand's disease (VWD) is the most common hereditary bleeding disorder. Unchecked or improperly managed, VWD-associated hemorrhage can lead to catastrophic surgical outcome. Based on the authors' recent experience with 21 procedures in 12 patients, a contemporary protocol for successful perioperative management of VWD in otolaryngologic surgery is presented. In patients with VWD type 1 or 2a, desmopressin, a synthetic vasopressin analog, is administered both pre- and postoperatively to release von Willebrand factor (VWF) from storage sites. In type 2b or 3, a factor VIII concentrate rich in VWF is administered. In addition, a 10- to 14-day course of intravenous and/or oral Amicar (Immunex Corp., Seattle, WA) may be prescribed postoperatively. Intraoperatively, the surgical laser is used to further decrease blood loss and augment hemostasis. This medical and surgical protocol minimizes the risk of hemorrhage and of transfusion-related complications through the judicious use of preoperative and postoperative coagulation replacement products. Using these guidelines in a variety of otolaryngologic cases, the authors have had no bleeding complications at their institution.

Misexpression of chick Vg1 in the marginal zone induces primitive streak formation

In the chick embryo, the primitive streak is the first axial structure to develop. The initiation of primitive streak formation in the posterior area pellucida is influenced by the adjacent posterior marginal zone (PMZ). We show here that chick Vg1 (cVg1), a member of the TGFbeta family of signalling molecules whose homolog in Xenopus is implicated in mesoderm induction, is expressed in the PMZ of prestreak embryos. Ectopic expression of cVg1 protein in the marginal zone chick blastoderms directs the formation of a secondary primitive streak, which subsequently develops into an ectopic embryo. We have used cell marking techniques to show that cells that contribute to the ectopic primitive streak change fate, acquiring two distinct properties of primitive streak cells, defined by gene expression and cell movements. Furthermore, naive epiblast explants exposed to cVg1 protein in vitro acquire axial mesodermal properties. Together, these results show that cVg1 can mediate ectopic axis formation in the chick by inducing new cell fates and they permit the analysis of distinct events that occur during primitive streak formation.

Implants in rhinoplasty

A variety of materials have been employed in rhinoplasty for augmentation and reconstruction. While autogenous tissue remains the mainstay of nasal implants and are the clear choice for structural and augmentation grafting of the nasal tip, limited availability and unpredictable resorption or remodeling have made homologous and synthetic implants important considerations for dorsal augmentation grafting. This section discusses categories of graft materials, their physical properties, harvesting and preparation technique, and advantages and disadvantages. An algorithm for nasal implants for specific indications in support and augmentation is presented.

Acoustic neuroma surgery: outcome analysis of patient-perceived disability

OBJECTIVE

Numerous studies have investigated the outcome of acoustic neuroma (AN) treatment using classical medical measures. In an effort to describe the long-term lifestyle consequences of AN removal from the patient's perspective, patients filled out detailed questionnaires concerning their functional status.

STUDY DESIGN

This was a retrospective survey.

SETTING

This study was performed at a tertiary referral center.

PATIENTS

A total of 130 late postoperative acoustic neuroma patients were surveyed a minimum of 6 months following surgery (average, 39 months). Survey response rate was 65% (130/200).

MAIN OUTCOME MEASURES

The main outcome measures were the patient's perception of their hearing, balance, facial expression, and eye function in relation to its impact upon the activities of daily life. A comparison of pretreatment with long-term posttreatment functional levels.

RESULTS

When asked to designate their "most significant" symptom, hearing loss was by far most prevalent (61.3%), followed by balance troubles (14.3%) and facial weakness (10.1%). The relatively low incidence of facial weakness as the patient's dominant complaint was somewhat surprising. When considering the incidence of each symptom, women were more likely to complain of facial weakness, dry eye, and headache, whereas men had a marginally higher incidence of hearing loss and imbalance. Patient age had no apparent influence upon either the distribution or severity of symptomatic complaints. Both hearing in the tumor ear and overall auditory function (e.g., the ability to understand in a restaurant) tended to worsen following surgery. One finding, which was both unanticipated and intriguing, was the improvement in sound localization ability reported by 57% of patients following surgery. Although the proportion of patients complaining of frequent tinnitus increased postoperatively, the number of patients who found the tinnitus troublesome decreased markedly. In terms of balance function, only 31% preoperatively and 15% postoperatively described themselves as free of balance difficulties. An aid to ambulation (e.g., cane, walker) was needed in five patients (4%) preoperatively, two of whom regained the ability to walk independently following tumor removal.

CONCLUSIONS

These functional outcome data provide much useful information to both patient and clinician to consider when contemplating the optimal course of AN management. Although virtually all acoustic neuroma patients have some degree of persistent symptoms over the long-term, the data indicates that most of these are attributable to the tumor itself as opposed to the after effects of its surgical removal. The relatively slight differences between preoperative and late postoperative symptom profiles was a rather unanticipated finding. As the degree of disability tends to increase with larger tumor sizes, these data tend to support a policy of early intervention.

Socioeconomic impact of acoustic neuroma surgery

OBJECTIVE

This study aimed to assess the impact of acoustic neuroma (AN) surgery on socioeconomic function.

STUDY DESIGN

This study was a retrospective postal survey.

SETTING

The study was performed at a tertiary referral center.

PATIENTS

One hundred thirty late postoperative AN patients were surveyed a minimum of 6 months after surgery (average 39 months). The survey response rate was 65% (130 of 200).

MAIN OUTCOME MEASURES

These included effect of AN surgery on employability, income, activities of daily living, social involvement, and psychological well-being.

RESULTS

When comparing preoperative occupational status with latest follow-up, 2 of 125 (1.6%) became unemployed from their usual occupations. An additional 15 of 125 (12%) retired, attributing their retirement to the effects of the tumor itself (3), an aftermath of surgery (2), and causes unrelated to their AN (10). After AN removal, two formerly unemployed patients became employed. Among those remaining employed, there was no significant impact of surgery on either income or work responsibility. Return to normal activity was gradual: < or = 6 weeks, 31%; < or = 3 month, 64%; and < or = 6 months, 84%. Among activities of daily living, the tasks most often impaired (both before and after tumor removal) were ladder climbing and night driving, whereas dressing and bathing were seldom problematic. Overall, patients reported a minor decline in ability to perform routine daily activities after tumor removal. Social function (contact with friends, community involvement, and participation in sports) changed little after surgery. The incidence of both stress and depression decreased slightly after tumor removal.

CONCLUSIONS

The economic, social, and psychological impact of AN and its surgical management appears to be relatively minor, with few individuals having life altering consequences.

Structural changes in oocyte nucleoli of Xenopus laevis during oogenesis and meiotic maturation

Immunoelectron microscopy with anti-nucleolin defined substructures within the multiple nucleoli of biosynthetically active stage II-III oocytes and within the nucleoli of relatively quiescent stage VI oocytes of Xenopus laevis. Dense fibrillar components (DFCs) of nucleoli from stage II-III oocytes consisted of nucleolonemas that radiated from a continuous DFC sheath surrounding fibrillar centers (FCs). Discernible granular regions (GRs) were absent in these same nucleoli. Conversely, stage VI oocyte nucleoli displayed compacted DFCs and prominent GRs. Immunofluorescence microscopy then tracked fibrillarin, nucleolin, and condensed DNA through oogenesis and into progesterone-induced meiotic maturation and nuclear breakdown. In stage II-III oocyte nucleoli, fibrillarin was enriched near the FC-DFC boundaries, while nucleolin was distributed throughout these same DFCs. Both proteins were enriched within the compacted DFCs of stage VI oocyte nucleoli. Staining with (DAPI) 4',6-diamidino-2-phenylindole showed condensed DNA within nucleolar FCs of both stage II-III and stage VI oocyte. Upon nuclear breakdown, we found fibrillarin and nucleolin in small particles and in the surrounding cytoplasm. Although we saw no trace of fibrillarin or nucleolin in nuclear remnants prepared just minutes later, DAPI-stained particles remained within these preparations, thus suggesting that FCs were at least slow to disassemble.

An extended study: protective effects of nerve growth factor in neomycin-induced auditory neural degeneration

Intracochlear survival of auditory neurons is thought to be a factor contributing to the success of cochlear implantations. Damage to the cochlear end-organ is frequently associated with loss of neurites in the osseous spiral lamina. The authors have previously reported a model for long-term intracochlear administration of pharmacologic agents using a technique and device analogous to a cochlear implant. These studies suggest that nerve growth factor (NGF) protects the auditory nerve from the immediate neurotoxic effects of neomycin. The intent of the present investigation is to determine whether NGF can protect auditory neural elements from neomycin-induced degeneration after several weeks have elapsed between the neomycin perfusion and the administration of NGF. Neomycin was infused over 24 hours through an indwelling, intracochlear cannula attached to a mini osmotic pump to unilaterally destroy the cochlear end-organ. The pump perfused the cochlea with artificial perilymph for 2 weeks. Then, the pump reservoirs were surgically replaced; the new reservoirs delivered either NGF or artificial perilymph for an additional 2 weeks. Spiral ganglion cell densities were measured along Rosenthal's canal in the basal, middle, and apical cochlear turns. This investigation revealed that NGF prevented auditory nerve degeneration over the 2-week period, when compared to controls, and that the protective effect was greatest in the neural elements closest to the source of NGF.

Enhanced preservation of the auditory nerve following cochlear perfusion with nerve growth factors

Survival of auditory neurons in the cochlea is thought to be an important factor in the success of cochlear implantations. Damage to the cochlear end-organ often produces loss of dendrites in the osseous spiral lamina. The authors have established a method that delivers water soluble pharmacologic agents to the cochlea using a mini osmotic pump with a polyethylene cannula that is inserted into the scala tympani via cochleostomy. The cannula is filled with an ototoxic agent, neomycin, that destroys the end-organ over the first 24 hours after insertion. Nerve growth factor (NGF), or a control substance, is placed in the pump reservoir and is pumped into the cochlea over a 2-week period. In this study, auditory nerve fibers in the osseous spiral lamina were counted in the apical, middle, and basal turns of the cochlea in 16 guinea pigs. At each location, fiber counts were significantly higher when neomycin was followed by perfusion with NGF, than when it was followed by infusion with control substances. The study demonstrates that NGF confers some protection against ototoxic induced degeneration of the auditory nerve in vivo.

A model for long-term intracochlear administration of pharmacologic agents

A technique is described that provides a method to study the effects of intracochlear pharmacologic agents on the degenerating auditory nerve. The model involves implanting a guinea pig with an osmotic minipump that allows slow perfusion of the cochlea over a period of hours to days with up to two water soluble substances. Neomycin and horseradish peroxidase, whose histopathologic effects on the cochlea are well known, are used in the present study to validate the efficacy of the system.

Doubting atopy?

Sera of 37 patients attending the allergic clinic and of 10 normal healthy non-allergic controls were collected and in a double blind manner they were tested using phadiatop RIA for differentiation of patient's symptoms as due to atopy or otherwise without performing other troublesome investigations. It is an easy, less time consuming and reliable technique.

Post-thaw storage at 4 degrees C of previously frozen red cells with retention of 2,3-DPG

Fresh human blood was collected in CPD, frozen by either the Meryman or the Valeri high glycerol technique, and stored at -80 degrees C. Later the red cells were thawed, deglycerolized by the appropriate technique and resuspended in either saline-glucose wash solution or an additive solution containing ascorbate-2-phosphate, adenine, glucose (dextrose), mannitol and sodium phosphate. The cells were stored at 4-6 degrees C for 21 days and assayed weekly for ATP, 2,3-DPG, pH, P50, glucose utilization and lysis. The additive solution maintained red cell 2,3-DPG at fresh blood levels for 3 weeks and maintained ATP levels sufficiently well to suggest good red cell viability for 21 days. There was no difference in results between the Meryman or the Valeri freezing methods if sodium phosphate was used with the saline-glucose wash solution in the Valeri method. If this additive solution is coupled with sterile deglycerolization techniques, 3 weeks of post-thaw red cell preservation would be practical. Using this additive solution would make frozen blood a reasonable source of red cells for emergency needs in both military and civilian blood banking.