Efficient and fast targeted production of murine models based on ENU mutagenesis

Mice with targeted genetic alterations are the most effective tools for deciphering organismal gene function. We generated an ENU-based parallel C3HeB/FeJ sperm and DNA archive characterized by a high probability to identify allelic variants of target genes as well as high efficiencies in allele retrieval and model revitalization. Our archive size of over 17,000 samples contains approximately 340,000 independent alleles (20 functional mutations per individual sample). Based on an estimated number of approximately 30,000 mouse genes, the parallel sperm/DNA archive should permit the identification and recovery of ten or more alleles per average target gene which translates to a calculated 99% success rate in the discovery of five allelic variants for any given average gene. The low rate of unrelated ENU-induced passenger mutations has no practical impact on the analysis of the allele-specific phenotype at the G3 generation because of dilution and free segregation of such unrelated passenger mutations. To date 39 mouse models representing 33 different genes have been recovered from our archive using in vitro fertilization techniques. The generation time for a murine model heterozygous for a mutation in a gene of interest is less than 2 months, i.e., three to four times faster compared with current embryonic stem-cell-based technologies. We conclude that ENU-based targeted mutagenesis is a powerful tool for the fast and high-throughput production of murine gene-specific models for biomedical research.

Reactions of Perennial Grain Accessions to Four Major Cereal Pathogens of the Great Plains

Methods of disease management used in annual grain crops, especially cultural practices designed to disrupt the disease cycle of a particular pathogen, will not necessarily be applicable to perennial grain crops. Resistance to multiple pathogens, therefore, will clearly be important in disease management. The objective of this research was to evaluate disease resistance in 10 perennial grain accessions (one to two accessions of each: perennial wheat (Thinopyrum sp. × Triticum aestivum), intermediate wheatgrass (Thinopyrum intermedium), perennial rye (Secale montanum), hexaploid triticale (Triticum turgidum × S. montanum), octoploid triticale (Triticum aestivum × S. montanum), tetraploid perennial rye (Secale cereale × S. montanum), and tall wheat-grass (Thinopyrum ponticum)) to tan spot (caused by Pyrenophora tritici-repentis), take-all (caused by Gaeumannomyces graminis var. tritici), wheat streak mosaic, and barley yellow dwarf, four important diseases of the Great Plains. Several of the grasses were resistant to tan spot, barley yellow dwarf, and wheat streak mosaic. Indeed, the wild grasses and perennial donors T. intermedium (including BFPMC1), T. ponticum, and S. montanum, in addition to Permontra, a tetraploid perennial rye, were highly resistant to all three diseases. Additionally, the remaining grasses tested were also more resistant to tan spot than the susceptible wheat control. However, none of the 10 grass accessions appeared highly resistant to take-all, and substantial losses in biomass were observed, although such effects may be moderated under field conditions due to the potential for take-all decline in perennial plantings.

Risk assessment model for venothromboembolism in post-hospitalized patients

AIM

Venothromboembolism (VTE) is an important condition in hospitalized patients accounting for significant morbidity and mortality, and the risk of VTE often continues post-hospitalization. Although risk assessment models have been developed to predict the risk of deep venous thrombosis (DVT) in hospitalized patients, no models have been developed that determine the risk of DVT during the post-hospitalization period. The objective of this study was to create a risk profile using risk factor assessment that could be used to predict which patients are at highest risk of developing DVT within 60 days following hospital discharge.

METHODS

The computerized medical records of 380 patients (190 with DVT and 190 without DVT) who received care from 1995-2002 and were subsequently re-hospitalized within 60 days of discharge were retrospectively reviewed. Univariate and multivariate logistic regression analyses were conducted to identify risk variables related to VTE. A novel risk assessment model was created using risk factors from the logistic regression analyses.

RESULTS

The prevalence of VTE was found to be 93.2% (69/74) in the high-risk category, 52.9% (109/206) in the moderate-risk category, and 12% (12/100) in the low-risk category.

CONCLUSIONS

Once validated, this risk assessment model may be applied to identify patients who may be at increased risk of developing VTE post-hospitalization. Those at high risk should be considered for anticoagulation therapy during the post-hospitalization period. Availability of a risk profile using risk factor assessment to guide decisions related to anticoagulation therapy will have important ramifications relative to patient outcomes including morbidity, mortality, and reductions in VTE-associated cost.

Reduction in Slippage with 11-cm Lap-Band® and Change of Gastric Banding Technique

BACKGROUND

Slippage occurs after 2-18% of gastric bandings performed by the perigastric technique (PGT). We investigated the slippage-rate before and after the introduction of the pars flaccida technique (PFT) and the 11-cm Lap-Band, and the long-term results of the re-operated patients.

METHODS

Between Dec 1996 and Feb 2004, 360 patients with a mean BMI of 44 kg/m2 were operated. The PGT (n=168) and PFT9.75 (n=15) groups received the 9.75-cm Lap-Band, and the PFT11 group (n=177) received the new 11-cm Lap-Band. Follow-up rate was 99%.

RESULTS

Slippage occurred in a total of 31 patients from all groups (PGT, n=28, or 17%; PFT9.75, n=1, or 7%; PFT11, n=2, or 1%). Average yearly re-operation rate for slippage in the first 3 years postoperatively was 3.8%, 2.2% and 0.9%, respectively. Laparoscopic re-banding was necessary for posterior (n=19) or lateral (n=12) slippage. The late postoperative course after re-banding was: uneventful 58%, weight regain 35% and/or esophageal motility disorder 23%, secondary band intolerance 20%, and one persistent posterior slippage. 8 patients (26%) needed biliopancreatic diversion.

CONCLUSION

Since the introduction of the PFT and the 11-cm Lap-Band, we observed a significant reduction in slippage rate and no posterior slippage. Re-banding had a less favorable long-term result than did first-procedure banding.

Validation of dynamic heart models obtained using non-linear registration for virtual reality training, planning, and guidance of minimally invasive cardiac surgeries

Current minimally invasive techniques for beating heart surgery are associated with three major limitations: the shortage of realistic and safe training methods, the process of selecting port locations for optimal target coverage from X-rays and angiograms, and the sole use of the endoscope for instrument navigation in a dynamic and confined 3D environment. To supplement the current surgery training, planning and guidance methods, we continue to develop our Virtual Cardiac Surgery Planning environment (VCSP) -- a virtual reality, patient-specific, thoracic cavity model derived from 3D pre-procedural images. In this work, we create and validate dynamic models of the heart and its components. A static model is first generated by segmenting one of the image frames in a given 4D data set. The dynamics of this model are then extracted from the remaining image frames using a non-linear, intensity-based registration algorithm with a choice of six different similarity metrics. The algorithm is validated on an artificial CT image set created using an excised porcine heart, on CT images of canine subjects, and on MR images of human volunteers. We found that with the appropriate choice of similarity metric, our algorithm extracts the motion of the epicardial surface in CT images, or of the myocardium, right atrium, right ventricle, aorta, left atrium, pulmonary arteries, vena cava and epicardial surface in MR images, with a root mean square error in the 1 mm range. These results indicate that our method of modeling the motion of the heart is easily adaptable and sufficiently accurate to meet the requirements for reliable cardiac surgery training, planning, and guidance.

[Autoantibodies against islet cell antigens and type 1 diabetes after treatment with interferon-alpha]

BACKGROUND AND OBJECTIVE

The aim of this study was to study the appearance of autoantibodies against islet cells and the development of type 1 diabetes in patients with chronic hepatitis C during interferon treatment.

PATIENTS AND METHODS

74 patients (24 women, 50 men, mean age: 46 years) with HCV infection were treated with interferon, ribavirin and amantadin versus placebo, after they had failed to previous interferon therapy in a prospective, randomised trial. At the end of treatment period anti-islet cell autoantibodies (anti-GAD, anti IA-2), anti-insulin antibodies, TSH, anti-thyroid autoantibodies (TPO, thyreoglobulin, TSH-receptor antibodies) were measured.

RESULTS

In two patients, GAD autoantibodies were found, but both patients were negative for IA-2 and insulin antibodies. One of the patients developed type 1 diabetes five months after start of treatment. In this patient, the anti-GAD titer was initial 0 U/ml (normal: < 1.2). The titer raised to 52,2 U/ml after the interferon monotherapy. During the second interferon treatment (in combination) the titer raised from initial 41,1 U/ml to 59,6 U/ml. The anti-GAD titer of the second patient was 0 U/ml before treatment and raised to 1,7 U/ml. This patient did not develop a type 1 diabetes.

CONCLUSION

Type 1 diabetes is a rare but serious complication of interferon therapy. Repetitive treatment seems to facilitate this complication. Screening for islet antibodies before a second therapy could be useful.

Augmented reality laser projection device for surgery

We have developed an augmented reality system capable of projecting preoperative plans directly onto a patient using rapidly scanned laser beams. Projected contours can typically represent cut paths, tumors or delineate boundaries of interest. The system can be used as part of, or a replacement for, conventional robotic Telesurgery systems. Because the graphics are projected, there is no degradation in surgeon's view due to optical components interposed between the surgeon's eye and the patient. This system has been designed to work with a common infrared 3D camera system used in image-guided surgery, and projects both visible and infrared beams. The IR beam enables surface digitization functions to be carried out using the camera. The clinical accuracy is in the range required by CAS procedures, around 1-2mm. The device will be particularly useful for executing precise preoperative plans and for teleconsultation applications, where planned or live consultations can be efficiently communicated to a less skilled local caregiver.

Alopecia in a novel mouse model RCO3 is caused by mK6irs1 deficiency

Reduced coat 3 (Rco3) is a new spontaneous autosomal recessive mutation with defects in hair structure and progressive alopecia. Here we describe chromosomal mapping and molecular identification of the Rco3 mutation. The murine Rco3 locus maps to a 2-Mb interval on chromosome 15 encompassing the keratin type II gene cluster. Recently, mK6irs1 was described as a type II keratin expressed in Henle's and Huxley's layer of the murine inner root sheath. Genomic sequencing revealed a 10-bp deletion in exon 1 of mK6irs1 resulting in a frameshift after 58 amino acid residues and, therefore, the absence of 422 carboxy-terminal amino acid residues containing the complete alpha-helical rod domain. Henle's and Huxley's layers show no immunoreactivity with mK6irs1-specific antibodies and the absence of intermediate filament formation in electron microscopic images. These results indicate that the expression of functional mK6irs1 is indispensable for intermediate filament formation in the inner root sheath and highlights the importance of the keratinization of the inner root sheath in the normal formation of the hair shaft.

Long-term growth arrest of PUVA-treated fibroblasts in G2/M in the absence of p16INK4a, p21CIP1or p53

Premature aging of the skin is a prominent side-effect of psoralen photoactivation, a therapy used for different skin disorders. Recently, we demonstrated that treatment of fibroblasts with 8-methoxypsoralen and ultraviolet A irradiation resulted in growth arrest with morphological and functional changes reminiscent of replicative senescence. To further elucidate the underlying molecular mechanisms, we analysed the cell-cycle phases of the growth-arrested fibroblasts. After PUVA treatment, fibroblasts arrested in G2/M, in contrast to spontaneously senesced fibroblasts arresting in a cell-cycle phase with many features similar to G1. To address the role of the cell-cycle controlling genes p16(INK4a), p21(CIP1) and p53, we analysed the expression of these genes. p16(INK4a), p21(CIP1) and p53 protein levels increased substantially with different time kinetics in growth-arrested fibroblasts. Because p16(INK4a), p21(CIP1) and p53 are involved in replicative senescence, we applied the PUVA regimen to fibroblasts deficient in either of these genes. p16(INK4a), p21(CIP1) and p53 null mutant fibroblast strains underwent growth arrest with a senescent phenotype similar to wild-type human fibroblasts. Based on these results, we propose that redundant or alternate pathways are involved in the response of dermal fibroblasts to PUVA treatment resulting in a phenocopy of replicative senescence in vitro.

A mouse model for cystinuria type I

Cystinuria, one of the most common inborn errors of metabolism in humans, accounts for 1-2% of all cases of renal lithiasis. It is caused by defects in the heterodimeric transporter system rBAT/b0,+AT, which lead to reduced reabsorption of cystine and dibasic amino acids through the epithelial cells of the renal tubules and the intestine. In an N-ethyl-N-nitrosourea mutagenesis screen for recessive mutations we identified a mutant mouse with elevated concentrations of lysine, arginine and ornithine in urine, displaying the clinical syndrome of urolithiasis and its complications. Positional cloning of the causative mutation identified a missense mutation in the solute carrier family 3 member 1 gene (Slc3a1) leading to an amino acid exchange D140G in the extracellular domain of the rBAT protein. The mouse model mimics the aetiology and clinical manifestations of human cystinuria type I, and is suitable for the study of its pathophysiology as well as the evaluation of therapeutic and metaphylactic approaches.

Population requirement for primary knee replacement surgery: a cross-sectional study

OBJECTIVES

To determine the population requirement for total knee replacement (TKR) in England.

METHODS

Population-based study using an age/sex-stratified random sample of 28 080 individuals aged 35 yr and over. Incident disease was estimated from prevalence by statistical modelling. The New Zealand priority criteria for major joint replacement were used for case selection.

RESULTS

Patients with knee disease were less likely than those with equally severe hip disease to have been referred to a specialist, to have consulted an orthopaedic surgeon or to be on a waiting list for joint replacement. The estimated annual requirement of TKRs in England, based on New Zealand Scores alone, was 55,800 (95% CI 40 700-70,900), contrasting sharply with an annual provision of 29,300 actually observed. However, in contrast to previously reported hip replacement data, when patient willingness to undergo surgery was considered, this estimate decreased considerably.

CONCLUSIONS

There appears to be an underprovision of TKR in England. This may be due in part to differences in perception of disease severity and likely response to surgery between patients and general practitioners on one hand, and rheumatologists and orthopaedic surgeons on the other.