Use of extendable total femoral replacements in children with malignant bone tumors

Although rarely required, extendable reconstruction devices for replacing the entire femur offer children with malignant bone tumors the opportunity of a nearly normal development by overcoming an expected leg length discrepancy. Femoral integrity can be restored, allowing most patients to walk without the use of aids. There are no data available to provide evidence regarding long term results and morbidity in such patients. Six patients (range 2-12 years of age), three with osteogenic osteosarcoma and three with Ewing's sarcoma, were treated between 1988 and 1996 with custom made Stanmore extendable prosthetic total femoral replacements. One patient died 12 months after surgery because of complications relating to pulmonary metastasis. The remaining five patients were observed between 2.7 and 8.9 years (average, 5 years). No tumor recurrence has been recorded and no amputation has been performed. All surviving patients underwent an average of 9.4 operative procedures (range, 4-16 procedures) including 6.4 extension procedures (range, 3-10 procedures), and one prosthetic revision (range, 0-3 procedures). Five revisions in two patients were necessary because of infection, loosening of the prosthesis, mismatch between femoral head and acetabulum, or full extension of the extending mechanism. The functional results were measured in accordance with the Musculoskeletal Tumor Society rating score, with an average result of 77.3%. Total femoral replacement in a growing individual achieves good functional results yet has various risks for an uncertain outcome. Careful selection of the patient and realistic appraisal of the long term prospects are essential for successful treatment.     

The use of tailed octamer primers for cycle sequencing

Studies have been carried out on the use of octamer oligonucleotides tailed with different base analogues as primers in cycle sequencing reactions. 5-Nitroindole tails improved the performance as primers of a number of octamers. A tail length of three or four 5-nitroindole residues significantly increased the sequencing signal intensity for almost all primers. The use of incomplete libraries of tailed octamer primers for primer walking is discussed.     

Indium-111-DTPA-folate as a potential folate-receptor-targeted radiopharmaceutical

Indium-111-labeled diethylenetriamine pentaacetic acid (DTPA)-folate was evaluated as a radiopharmaceutical for targeting tumor-associated folate receptors. METHODS: Athymic mice were subcutaneously inoculated with approximately 1.8 x 10(6) folate receptor-positive KB (human nasopharyngeal carcinoma) cells, yielding 0.2- to 0.6-g tumors in 15 days, at which time (111)In-DTPA-folate, (111)In-DTPA or (111)In-citrate was administered by intravenous injection. RESULTS: The (111)In-DTPA-folate conjugate afforded marked tumor-specific (111)In deposition in vivo using this mouse model. The involvement of the folate receptor in mediating tumor uptake of (111)In-DTPA-folate was demonstrated by the blocking of tumor uptake by coadministration of free folic acid (intravenous). The (111)In-DTPA-folate also shows folate receptor-mediated uptake and retention in the kidneys, presumably reflecting radiotracer binding to folate receptors of the proximal tubules. In control experiments, the (111)In-citrate radiopharmaceutical precursor was also shown to afford significant tumor uptake of (111)In, but with much poorer tumor-to-background tissue contrast than that obtained with (111)In-DTPA-folate. Unconjugated (111)In-DTPA showed no tumor affinity. CONCLUSION: Indium-111-DTPA-folate appears suitable as a radiopharmaceutical for targeting tumor-associated folate receptors.     

Alterations in intestinal barrier function do not predispose to translocation of enteric bacteria in gastroenterologic patients

The potential of electrospray mass spectrometry (ESMS) for the sequencing of glycopeptides was evaluated using quadrupole time-of-flight (QTOF) technology in the MS/MS mode. The location of O-glycosylation sites was possible in the positive ion (+) mode by detection of prominent y- and b-fragment ions from the underivatized TAP25-2 [T1APPAHGVT9S10APDT14RPAPGS20T21APPA], an overlapping sequence of MUC1 tandem repeats which had been glycosylated in vitro by two GalNAc residues in the positions T9 and T21. The high mass resolution and accuracy of QTOF-(+)ESMS allowed reliable structural assignments. The reduced complexity of the fragment spectra and the higher signal-to-noise ratio render QTOF-(+)ESMS an alternative mass spectrometric approach to the identification of O-glycosylation sites when compared with sequencing by post-source decay matrix-assisted laser desorption/ionization MS. Diagnostic ions from the N-terminus in the b-series offered direct evidence, which was supported by indirect evidence from the C-terminus ions of the y-series. The higher glycosylated GalNAc2-substituted fragments were mainly observed as multiply ionized species.     

Prospective epidemiologic evaluation of laboratory animal allergy among university employees

OBJECTIVES: Evaluation of incidence and risk factors for development of laboratory animal allergy (LAA) among new hires previously unexposed to lab animals. METHODS: Baseline, 6-month and yearly follow-up, questionnaires, pulmonary functions, and methacholine challenges were collected from 98 never-before occupationally exposed and 90 control laboratory researchers. The two groups were followed between 6 and 36 months. RESULTS: At baseline, there were no differences in atopy, pulmonary functions, or methacholine reactivity between the two groups. The incidence of work-related asthma was comparable in the two groups, approximately 2.5% at 6 months and 4.5% at 24 months. The rate of decline in FEV1 was statistically significantly greater in the animal-exposed than nonanimal-exposed workers, and animal-exposed smokers' FEV1 declined significantly more rapidly than any other groups'. CONCLUSION: Despite the low incidence of laboratory-animal allergy and work-related asthma in this group, this study corroborates previously described interaction between smoking and animal exposure.     

Membrane targeting of p21-activated kinase 1 (PAK1) induces neurite outgrowth from PC12 cells

Rho-family GTPases regulate cytoskeletal dynamics in various cell types. p21-activated kinase 1 (PAK1) is one of the downstream effectors of Rac and Cdc42 which has been implicated as a mediator of polarized cytoskeletal changes in fibroblasts. We show here that the extension of neurites induced by nerve growth factor (NGF) in the neuronal cell line PC12 is inhibited by dominant-negative Rac2 and Cdc42, indicating that these GTPases are required components of the NGF signaling pathway. While cytoplasmically expressed PAK1 constructs do not cause efficient neurite outgrowth from PC12 cells, targeting of these constructs to the plasma membrane via a C-terminal isoprenylation sequence induced PC12 cells to extend neurites similar to those stimulated by NGF. This effect was independent of PAK1 ser/thr kinase activity but was dependent on structural domains within both the N- and C-terminal portions of the molecule. Using these regions of PAK1 as dominant-negative inhibitors, we were able to effectively inhibit normal neurite outgrowth stimulated by NGF. Taken together with the requirement for Rac and Cdc42 in neurite outgrowth, these data suggest that PAK(s) may be acting downstream of these GTPases in a signaling system which drives polarized outgrowth of the actin cytoskeleton in the developing neurite.     

Technical and economic feasibility of reusing disposable perfusion cannulas

OBJECTIVE(S): The reuse of disposable devices is a potential source of significant cost savings to hospitals. Venous and arterial perfusion cannulas under new and reused conditions were selected to identify the clinical, safety, technical, logistic, and economic issues that must be addressed to realize these savings. METHODS: Single- and dual-stage venous and arterial cannulas from two manufacturers were tested when new, after initial clinical use, and after a single clinical use plus up to nine simulated reuses. Reuse was simulated by end-to-end bending, coupling and uncoupling of the connectors, and by two 1-hour soaks in plasma at 4 degrees and 40 degrees C, respectively. Cannulas were decontaminated and then processed by a peracetic acid-based liquid chemical sterilization system after each use/reuse. Sterilization was validated by eliminating Bacillus subtilis spores from the cannulas on each of five consecutive cycles. Cannulas were tested for physical changes, functional integrity, biocompatibility, and in vivo performance in sheep. A cost analysis was also performed. RESULTS: Sterilization was successfully achieved. Mechanical changes were less than 20% on all variables studied and were undetectable by experienced cardiac surgeons in selective evaluation. No clinically important differences were found between new and reused cannulas, even after nine simulated reuses. Reusing cannulas four times would reduce the cost per procedure from $53 to $19 (64%). CONCLUSIONS: Preliminary data suggest that the perfusion cannulas tested can be safely and efficaciously used five times. Limited reuse of these disposable cannulas is technically feasible and cost-effective. Cannula reuse would result in a small incremental savings; however, with more expensive devices and higher-volume sterilization procedures, the savings could be considerably greater. This program provides a model for evaluation of other single-use medical devices for reuse.     

Bilateral neuropathologic changes in a child with hemimegalencephaly

Evaluation of a 7-month-old girl with developmental delay and intractable seizures revealed hemispheric asymmetry and an enlarged right cerebral hemisphere. Because of a history of seizures refractory to medical therapy, she was admitted for right hemispherectomy, but died of complications of surgery. Postmortem brain examination revealed asymmetric enlargement of the right cerebral hemisphere but no gross abnormalities in the left hemisphere. Microscopic examination demonstrated bilateral neuropathologic changes consistent with severe cortical dysplasia in the right cerebral hemisphere and mild cortical dysplasia in the left. Although white matter abnormalities in the unaffected hemisphere have been reported in hemimegalencephaly, bilateral cortical abnormalities, not reported previously in patients with hemimegalencephaly, may account for the varied clinical outcome with medical therapy or after hemispherectomy.