Production and characterization of murine models of classic and intermediate maple syrup urine disease

Background  

Maple Syrup Urine Disease (MSUD) is an inborn error of metabolism caused by a deficiency of branched-chain keto acid dehydrogenase. MSUD has several clinical phenotypes depending on the degree of enzyme deficiency. Current treatments are not satisfactory and require new approaches to combat this disease. A major hurdle in developing new treatments has been the lack of a suitable animal model.     

Regulation of DAF-2 receptor signaling by human insulin and ins-1, a member of the unusually large and diverse C. elegans insulin gene family

The activity of the DAF-2 insulin-like receptor is required for Caenorhabditis elegans reproductive growth and normal adult life span. Informatic analysis identified 37 C. elegans genes predicted to encode insulin-like peptides. Many of these genes are divergent insulin superfamily members, and many are clustered, indicating recent diversification of the family. The ins genes are primarily expressed in neurons, including sensory neurons, a subset of which are required for reproductive development. Structural predictions and likely C-peptide cleavage sites typical of mammalian insulins suggest that ins-1 is most closely related to insulin. Overexpression of ins-1, or expression of human insulin under the control of ins-1 regulatory sequences, causes partially penetrant arrest at the dauer stage and enhances dauer arrest in weak daf-2 mutants, suggesting that INS-1 and human insulin antagonize DAF-2 insulin-like signaling. A deletion of the ins-1 coding region does not enhance or suppress dauer arrest, indicating a functional redundancy among the 37 ins genes. Of five other ins genes tested, the only other one bearing a predicted C peptide also antagonizes daf-2 signaling, whereas four ins genes without a C peptide do not, indicating functional diversity within the ins family.     

Cloning, expression and functional characterisation of a peroxiredoxin from the potato cyst nematode Globodera rostochiensis

We report the cloning, expression and functional characterisation of a peroxidase belonging to the peroxiredoxin family from the potato cyst nematode Globodera rostochiensis, the first molecule of this type from any nematode parasitic on plants. The G. rostochiensis peroxiredoxin catalyses the breakdown of hydrogen peroxide, but not cumene or t-butyl hydroperoxide, in a trypanosomatid reducing system comprising trypanothione reductase, trypanothione and tryparedoxin. In common with its homologues from Onchocerca volvulus and Brugia malayi, the G. rostochiensis enzyme is present on the surface of invasive and post-infective juveniles despite the apparent lack of a cleavable N-terminal signal peptide. The possibility that the G. rostochiensis peroxiredoxin plays a role in protection of the parasite from plant defence responses is discussed.     

Interlaboratory validation of a CD71-based flow cytometric method (Microflow) for the scoring of micronucleated reticulocytes in mouse peripheral blood

An interlaboratory study was performed to validate an anti-CD71/flow cytometry-based technique for enumerating micronucleated reticulocytes (MN-RETs) in mouse peripheral blood. These experiments were designed to address International Workshop on Genotoxicity Test Procedures validation criteria by evaluating the degree of correspondence between MN-RET measurements generated by flow cytometry (FCM) with those obtained using traditional microscopy-based methods. In addition to these cross-methods data, flow cytometric MN-RET measurements for each blood sample were performed at two separate sites in order to evaluate the reproducibility of data between laboratories. In these studies, groups of male CD-1 mice were treated with vehicle (saline or vegetable oil), a negative control (saline or vegetable oil), or four dose levels of five known genotoxicants (clastogens: cyclophosphamide, benzo[a]pyrene, 5-fluorouracil, methotrexate; aneugen: vincristine sulfate). Exposure occurred on 3 consecutive days via intraperitoneal injection, and blood samples were obtained approximately 24 hr after the final treatment. MN-RET frequencies were determined for each sample based on the analysis of 2,000 (microscopy) and 20,000 (FCM) reticulocytes. Regardless of the method utilized, each genotoxic agent was observed to cause statistically significant increases in the frequency of MN-RETs, and each response occurred in a dose-dependent manner. Spearman's correlation coefficient (rs) for FCM versus microscopy-based MN-RET measurements (nine experiments, 252 paired measurements) was 0.740, indicating a high degree of correspondence between methods. The rs value for all flow cytometric MN-RET measurements performed at the two independent sites was 0.857 (n = 248), suggesting that the automated method is highly transferable between laboratories. Additionally, the flow cytometric system offered advantages relative to microscopy-based scoring, including a greater number of cells analyzed, much faster analysis times, and a greater degree of objectivity. Collectively, data presented in this report suggest that the overall performance of mouse peripheral blood micronucleus tests is enhanced by the use of the flow cytometric scoring procedure.     

Oral tolerance in protein-deprived mice. I. Profound antibody tolerance but impaired DTH tolerance after antigen feeding.

We have examined the effects of protein deprivation on the induction of oral tolerance for systemic antibody and DTH responses to the protein antigen ovalbumin (OVA). Mice were fed 4% or 24% protein diets from weaning and given a single feed of OVA 2 weeks later (short-term deprivation) or after 10 weeks (long-term deprivation). Tolerance for serum antibody responses was more profound in protein-deprived animals than in 24% protein-fed control groups. Conversely, tolerance for DTH responses was impaired in protein-deprived mice. This was demonstrated both for short-term deprivation, where nutritional rehabilitation after OVA feeding was necessary to demonstrate this effect on DTH, and for long-term deprivation. Furthermore, the effect of short-term deprivation on tolerance for DTH responses was similar to that observed after cyclophosphamide pretreatment of OVA-fed mice. Protein deprivation has disparate effects on the humoral and cell-mediated limbs of oral tolerance, and our results support the hypothesis that this regime selectively depletes a population of suppressor T cells responsible for the fine control of DTH tolerance.     

Giant cell tumor of bone express p63.

p63 contributes to skeletal development and tumor formation; however, little is known regarding its activity in the context of bone and soft tissue neoplasms. The purpose of this study was to investigate p63 expression in giant cell tumor of bone and to determine whether it can be used to discriminate between other giant cell-rich tumors. Seventeen cases of giant cell tumor of bone were examined to determine the cell type expressing p63 and identify the isoforms present. Total RNA or cell protein was extracted from mononuclear- or giant cell-enriched fractions or intact giant cell tumor of bone and examined by RT-PCR or western blot, respectively. Immunohistochemistry was used to evaluate p63 expression in paraffin embedded sections of giant cell tumor of bone and in tumors containing multinucleated giant cells, including: giant cell tumor of tendon sheath, pigmented villonodular synovitis, aneurysmal bone cyst, chondroblastoma, and central giant cell granuloma. The mononuclear cell component in all cases of giant cell tumor of bone was found to express all forms of TAp63 (alpha, beta, and gamma), whereas only low levels of the TAp63 alpha and beta isoforms were detected in multinucleated cells; DeltaNp63 was not detected in these tumors. Western blot analysis identified p63 protein as being predominately localized to mononuclear cells compared to giant cells. This was confirmed by immunohistochemical staining of paraffin-embedded tumor sections, with expression identified in all cases of giant cell tumor of bone. Only a proportion of cases of aneurysmal bone cyst and chondroblastoma showed p63 immunoreactivity whereas it was not detected in central giant cell granuloma, giant cell tumor of tendon sheath, or pigmented villonodular synovitis. The differential expression of p63 in giant cell tumor of bone and central giant cell granuloma suggest that these two tumors may have a different pathogenesis. Moreover, p63 may be a useful biomarker to differentiate giant cell tumor of bone from central giant cell granuloma and other giant cell-rich tumors, such as giant cell tumor of tendon sheath and pigmented villonodular synovitis.     

Real-time nucleic acid sequence-based amplification using molecular beacons for detection of enterovirus RNA in clinical specimens

Real-time nucleic acid sequence-based amplification (NASBA) using molecular beacon technology (NASBA-beacon) was compared to standard NASBA with postamplification hybridization using electrochemiluminescently labeled probes (NASBA-ECL) for detection of enteroviruses (EV) in 133 cerebrospinal fluid and 27 stool samples. NASBA-ECL and NASBA-beacon were similar in sensitivity, detecting 55 (100%) and 52 (94.5%) EV-positive samples, respectively. There were no false positives. Both NASBA assays were significantly more sensitive than culture. Real-time NASBA-beacon reagents and equipment rental were more expensive than those for NASBA-ECL; however, time to result was shortened by 1.5 h, hands-on time was reduced by 25 min, and the assay was much simpler for technologists to learn and perform.     

Increasing transplant mass results in long-term allograft survival and recovery from transplant vasculopathy

Late allograft rejection due to transplant vasculopathy continues to be a major clinical problem. Increasing the ratio of donor transplant size to recipient weight has been shown to reduce the incidence of late allograft failure. Using a murine pancreas transplant model we have tested the hypothesis that increasing the donor transplant size in a recipient can promote long-term allograft survival by promoting recovery from transplant vasculopathy. Recipients of an allograft that showed extensive vasculopathy were transplanted with a second donor transplant. The effect of the second allograft on the vasculopathy present in the first graft was measured. Transplanting a second allograft reversed all signs of ongoing rejection, including transplant vasculopathy, resulting in long-term survival of the first graft. Vasculopathy was only reversed if the first and second grafts were from the same mouse strain, suggesting an antigen-specific mechanism. However, the recovery of the first graft was not associated with antigen-specific peripheral tolerance.     

End-stage renal disease and race: an overview and perspective

The epidemiology of end-stage renal disease (ESRD) in the United States is reviewed. Hypertension and diabetes as etiologic factors in ESRD in minorities are discussed, as is the question of a familial ESRD. It is hypothesized that diuretics as sole antihypertensive therapy in blacks may in the long term result in chronic volume contraction, increased sympathetic stimulation, and therefore, decreased renal function. As such, a rational basis for the long-term use of diuretics as the sole antihypertensive therapeutic in blacks becomes questionable at best.     

Substance P-immunoreactive nerves in the rat kidney

Previously published data have indicated that in the rat, unlike other species examined, the kidney is not supplied by sensory nerves containing substance P (SP). As part of a study of reflex control of renal function in the rat, we have now reassessed this situation. Many fine, varicose, SP-immunoreactive nerve fibers were found in the wall of the proximal ureter and the renal pelvis, and around the larger renal blood vessels. Sparser populations of similar nerves were also seen running close to proximal and distal tubules in the renal cortex. Occasional fibers were seen at the margins of the glomeruli. Our findings suggest that sensory nerves containing SP may carry sensory information of several types from the rat kidney.