Analytical validation of HER2DX genomic test for early-stage HER2-positive breast cancer.

BACKGROUND: HER2DX, a multianalyte genomic test, has been clinically validated to predict breast cancer recurrence risk (relapse risk score), the probability of achieving pathological complete response post-neoadjuvant therapy (pCR likelihood score), and individual ERBB2 messenger RNA (mRNA) expression levels in patients with early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This study delves into the comprehensive analysis of HER2DX's analytical performance. MATERIALS AND METHODS: Precision and reproducibility of HER2DX risk, pCR, and ERBB2 mRNA scores were assessed within and between laboratories using formalin-fixed paraffin-embedded (FFPE) tumor tissues and purified RNA. Robustness was appraised by analyzing the impact of tumor cell content and protocol variations including different instruments, reagent lots, and different RNA extraction kits. Variability was evaluated across intratumor biopsies and genomic platforms [RNA sequencing (RNAseq) versus nCounter], and according to protocol variations. RESULTS: Precision analysis of 10 FFPE tumor samples yielded a maximal standard error of 0.94 across HER2DX scores (1-99 scale). High reproducibility of HER2DX scores across 29 FFPE tumors and 20 RNAs between laboratories was evident (correlation coefficients >0.98). The probability of identifying score differences >5 units was ≤5.2%. No significant variability emerged based on platform instruments, reagent lots, RNA extraction kits, or TagSet thaw/freeze cycles. Moreover, HER2DX displayed robustness at low tumor cell content (10%). Intratumor variability across 212 biopsies (106 tumors) was <4.0%. Concordance between HER2DX scores from 30 RNAs on RNAseq and nCounter platforms exceeded 90.0% (Cohen's κ coefficients >0.80). CONCLUSIONS: The HER2DX assay is highly reproducible and robust for the quantification of recurrence risk, pCR likelihood, and ERBB2 mRNA expression in early-stage HER2-positive breast cancer.

Optimal conditions for high-power, short-duration radiofrequency ablation using a novel, flexible-tipped, force-sensing catheter.

Background: High-power, short-duration (HPSD) radiofrequency ablation (RFA) reduces procedure time; however, safety and efficacy thresholds vary with catheter design. Objective: The study sought to determine optimal HPSD ablation conditions with a novel flexible-tipped, contact force-sensing RFA catheter. Methods: RFA lesions were created in thigh muscle (16 swine) over a range of conditions (51-82 W, 2-40 g, 8-40 mL/min irrigation). An intracardiac study was performed (12 swine) to characterize steam pop thresholds. Lesions were created in a second intracardiac study (14 swine, n = 290 pulmonary vein isolation [PVI] lesions) with combinations of radiofrequency power, duration, and contact force. PVI was tested, animals were sacrificed, and lesions were measured. Results: The likelihood of coagulation formation in the thigh model was <20% when power was ≤79 W, when contact force was ≤40 g, when duration was ≤11 seconds, and when irrigation rates were 8 to 40 mL/min. The impact of contact force on lesion safety and efficacy was more pronounced using HPSD (60 W/8 seconds) compared with conventional ablation (30 W/45 seconds) (P = .038). During PVI, focal atrial lesions ranged in width from 4.2 to 12.5 mm and were transmural 80.8% of the time. PVI was achieved in 13 of 14 veins. Logistic regression identified that the optimal parameters for radiofrequency application were 60 to 70 W with a duration <8 seconds and <15 g contact force. Conclusions: Optimal HPSD lesions with this this flexible-tipped, force-sensing RFA catheter were created at 60 to 70 W for <8 seconds with <15 g contact force. Chronic studies are ongoing to assess radiofrequency parameter refinements and long-term lesion durability using these conditions.

Ocular Involvement in Transfusion Dependent Thalassemia Children.

Thalassemia is one of the most common haemoglobinopathies in the world. Transfusion dependent thalassemia patients need regular blood transfusion. Repeated blood transfusions lead to iron overloads which can affect various organs in the body including eyes. The present study aims to evaluate the ocular involvements in transfusion dependent thalassemia children and their relationship with duration of the disease and serum ferritin level. This cross-sectional observational study included 46 multi-transfused thalassemia children aged 3-18 years. Detailed ophthalmological examination including visual acuity, slit lamp bio microscopy, direct and indirect ophthalmoscopy was done. Statistical analysis was done using SPSS version (IBM) 23.0. Student's t-test and chi-square (χ²) test was done and p value of <0.05 was considered significant. Out of 46 thalassemia children male were 25(54.3%) and female were 21(45.7%). Mean age of the children was 8.94±5.04 years, mean duration of disease was 7.02±3.5 years and mean serum ferritin level 1543.68±914.43ng/dl. Ocular involvements were detected in 19(41.3%) children. Among them 8(17.39%) children had more than one ocular involvements. The ocular manifestations were decreased visual acuity in 17(36.95%), corneal dryness in 7(15.21%), lens opacity in 6(13.04%), optic disc atrophy in 7(15.21%), peripheral retinal pigmentation in 5(10.86%) and retinal vessels tortuosity in 3(6.52%) children. Higher serum ferritin level and increased duration of the disease were significantly (p<0.001) related with ocular involvement. Various ocular involvements were found in transfusion dependent thalassemia children. Therefore, transfusion dependent thalassemia children should be screened periodically for early detection and proper management of ocular changes.

Safe and effective delivery of high-power, short-duration radiofrequency ablation lesions with a flexible-tip ablation catheter.

Background: High-power, short-duration (HPSD) radiofrequency ablation (RFA) may reduce ablation time. Concerns that catheter-mounted thermocouples (TCs) can underestimate tissue temperature, resulting in elevated risk of steam pop formation, potentially limit widespread adoption of HPSD ablation. Objective: The purpose of this study was to compare the safety and efficacy of HPSD and low-power, long-duration (LPLD) RFA in the context of pulmonary vein isolation (PVI). Methods: An open-irrigated ablation catheter with a contact force sensor and a flexible-tip electrode containing a TC at its distal end (TactiFlexTM Ablation Catheter, Sensor EnabledTM, Abbott) was used to isolate the left pulmonary veins (PVs) in 12 canines with HPSD RFA (50 W for 10 seconds) and LPLD RFA (30 W for a maximum of 60 seconds). PVI was assessed at 30 minutes and 28 ± 3 days postablation. Computed tomographic scans were performed to assess PV stenosis after RFA. Lesions were evaluated with histopathology. Results: A total of 545 ablations were delivered: 252 with LPLD (0 steam pops) and 293 with HPSD RFA (2 steam pops) (P = .501). Ablation time required to achieve PVI was >3-fold shorter for HPSD than for LPLD RFA (P = .001). All 24 PVs were isolated 30 minutes after ablation, with 12/12 LPLD-ablated and 11/12 HPSD-ablated PVs still isolated at follow-up. Histopathology revealed transmural ablations for HPSD and LPLD RFA. No major adverse events occurred. Conclusion: An investigational ablation catheter effectively delivered RFA lesions. Ablation time required to achieve PVI with HPSD with this catheter was >3-fold shorter than with LPLD RFA.

A drug-induced hypotensive challenge to verify catheter-based radiofrequency renal denervation in an obese hypertensive swine model.

OBJECTIVE: Sham-controlled trials provided proof-of-principle for the blood pressure-lowering effect of catheter-based renal denervation (RDN). However, indicators for the immediate assessment of treatment success are lacking. This study sought to investigate the impact of RDN on renal renin arteriovenous difference (renal renin AV-Δ) following a hypotensive challenge (HC). METHODS: Twelve hypertensive Ossabaw swine underwent either combined surgical and chemical (n = 3) or catheter-based RDN (n = 9). A telemetry monitor was implanted to acquire hemodynamic data continuously. Before and after RDN, a sodium nitroprusside-induced HC was performed. Renal renin AV-Δ was calculated as the difference of plasma renin concentrations drawn from the renal artery and vein. RESULTS: In total, complete renal renin AV data were obtained in eight animals at baseline and six animals at baseline and 3 months of follow-up. Baseline renal renin AV-Δ correlated inversely with change in 24-h minimum systolic (- 0.764, p = 0.02), diastolic (r = - 0.679, p = 0.04), and mean (r = - 0.663, p = 0.05) blood pressure. In the animals with complete renin secretion data at baseline and follow-up, the HC increased renal renin AV-Δ at baseline, while this effect was attenuated following RDN (0.55 ± 0.34 pg/ml versus - 0.10 ± 0.16 pg/ml, p = 0.003). Renin urinary excretion remained unchanged throughout the study (baseline 0.286 ± 0.187 pg/ml versus termination 0.305 ± 0.072 pg/ml, p = 0.789). CONCLUSION: Renin secretion induced by HC was attenuated following RDN and may serve as an indicator for patient selection and guide successful RDN procedures.

Comparison of branch and distally focused main renal artery denervation using two different radio-frequency systems in a porcine model.

OBJECTIVES: Anatomic placement of lesions may impact efficacy of radio-frequency (RF) catheter renal denervation (RDN). However, it is unclear if it is necessary to perform treatments post bifurcation with systems that may provide deeper penetration to achieve successful RDN. METHODS: Sixteen domestic swine (n=16) were randomly assigned to 4 groups: 1) 8 lesions created in the branch arteries using the Spyral catheter (SP8); 2) 8 lesions created in the branch arteries plus 4 lesions created in the main artery using the SP catheter (SP12); 3) 8 lesions created in the main artery using the EnligHTN catheter with the distal position as close as possible to the bifurcation (EN8); and 4) 12 lesions created in the main artery using the EN catheter with the distal position as close as possible to the bifurcation (EN12). RESULTS: Each arm showed statistically significant changes in kidney norepinephrine (NE, ng/g) between treated kidneys vs. untreated contralateral control. There were no statistically significant differences in tissue NE% reductions across each arm based on catheter, anatomic location, & number of lesions (p=0.563): EN8 -74±34%, EN12 -95±3%, SP8 -76±16%, SP12 -82±17% (p=0.496). A total of 46 lesions were measured for lesion depth: EN main (3.3±2.8mm) vs. SP branch (2.0±1.0mm, p=0.039), SP main (2.9±1.6mm) vs. SP branch (p=0.052), and EN main vs. SP main (p=0.337). CONCLUSIONS: Distally-focused main renal artery treatment using the EN system appears to be equally efficacious in reducing tissue NE levels compared with SP treatment in the branches plus main renal arteries, advocating for device-specific procedure execution.

Catheter-based radio-frequency renal nerve denervation lowers blood pressure in obese hypertensive swine model.

OBJECTIVES: Radio-frequency renal denervation (RDN) therapy is under investigation for the treatment of uncontrolled hypertension. Data in hypertensive, drug-naïve large animal models using RDN is limited. METHODS: A cohort of Ossabaw swine (N = 9) was implanted with telemetry monitors, enrolled on a high calorie-feed regimen and randomly assigned to RDN. Blood pressure (BP) data were separated and analyzed according to the following epoch definitions: 24-h (h), most-active-h, light-h, and dark-h. RESULTS: The mean weight increased by 45% from 86.5 ±â€Š2.5 kg at telemetry implant (day 87) to 125.2 ±â€Š4.5 kg at time of RDN therapy (day 227). Hypertension developed in all swine (24-h BP: 169.5/128.3 ±â€Š5.8/5.1 mmHg pre-RDN). RDN resulted in significant reductions in noradrenaline kidney tissue concentration by 63%. Significant BP reductions were documented at 45 days post-RDN in all defined interday epochs, except for the dark-h period. The most pronounced SBP/DBP reduction was 12.4/11.2 mmHg (P < 0.05), observed during the most-active-h period. Animals continued to gain weight after the RDN procedure to the end of the study at 90 days (125.2 ±â€Š4.5-138.5 ±â€Š6.6 kg, P < 0.001). At 90 days post-RDN, the mean 24-h BP returned near pre-RDN baseline values. Given the strong relationship of BP to weight (R = 0.87, P < 0.001), group mean SBP/DBP was normalized by weight resulting in significant and continued reductions at both 45 and 90 days post-RDN across all intradaily epochs. CONCLUSION: Catheter-based RDN, using a multielectrode system, resulted in a significant reduction in 24-h BP in this drug-naïve, hypertensive animal model.

Trans-neuronal transduction of spinal neurons following cortical injection and anterograde axonal transport of a bicistronic AAV1 vector.

Adeno-associated viral (AAV) vectors are one of the most promising gene delivery systems to the central nervous system. We now report, that AAV1 can be used to express transgenes trans-neuronally in neurons distant from the injection site. Specifically, intracortical injection of a bicistronic AAV1 vector trans-neuronally transduced spinal neurons as shown by fluorescence microscopy, the presence of AAV genome and AAV transcript in the contralateral spinal cord. Prior pyramidotomy abolished spinal transduction, confirming anterograde axonal transport of AAV1 in the corticospinal tract. These observations demonstrate the potential of bicistronic AAV1 for trans-neuronal expression of therapeutic transgenes in neurological disorders or reporter genes in connectivity studies.

Citrobacter koseri septicaemia in a holstein calf.

A 4-day-old male Holstein calf with dull mentation, nystagmus and blindness was humanely destroyed and subject to necropsy examination. Gross lesions included severe suppurative meningitis characterized by diffuse cloudy thickening of the meninges, bilateral hypopyon and fibrinosuppurative polyarthritis affecting the hocks. Citrobacter koseri was isolated from the meninges, ocular fluid, synovial fluid, spleen and small intestine. Microscopically, there was neutrophilic and histiocytic meningitis with intralesional bacilli, endophthalmitis, neutrophilic splenitis and multiple renal microabscesses. Failure of passive transfer of colostrum was confirmed. This appears to be the first characterization of septicaemia in a calf caused by C. koseri, with lesions comparable with those described in human neonates.

"It could probably help someone else but not me": a feasibility study of a snack programme offered to meals on wheels clients.

OBJECTIVES: Community-based services, such as Meals on Wheels (MOW), allow older adults to remain in their homes for as long as possible. Many MOW recipients experience decreased appetite that limits intake at mealtimes. This pilot study aimed to determine the feasibility of providing high protein high energy snacks to improve nutrient intakes of MOW clients in a regional centre of New South Wales, Australia. PARTICIPANTS: A convenience sample of 12 MOW clients. INTERVENTION: Participants received snacks five times a week, in addition to their usual MOW order, for four weeks. MEASUREMENTS: Nutritional status was assessed using the Mini Nutritional Assessment tool. Pre-post changes in dietary intake were assessed using a diet history and food frequency questionnaire. Qualitative interviews conducted in clients' homes were digitally recorded, transcribed verbatim, and themes identified. RESULTS: Post-intervention, there was a trend for an increased energy (mean = +415kJ (SD=1477) /day) and protein (+7.2 (±14.06) g/day) intake. MNA scores significantly increased (P= 0.036) and proportion of respondents categorised as 'malnourished' or 'at risk of malnutrition' decreased from 17% to 8%, and 67% to 25%, respectively (P <0.05). Mean body weight increased from 67.1 (±14.3) to 67.8 (±14.8) (P= 0.008), while Body Mass Index (BMI) increased by a mean of 0.78 (±1.16) kg/m2 (P = 0.039). Only half of participants indicated interest in continuing with the program. Reasons included the role of snacks serving as a reminder to eat, as well as their perceived nutritional value. Identified barriers included perceived lack of need for additional food, ability to self-provide such items, and a perceived adequate health status. CONCLUSION: Provision of an additional daily mid-meal snack may be a useful addition to existing MOW services, for improved energy and protein intakes. However, not all MOW clients at risk of malnutrition perceived the snacks to be beneficial to them.

Efficient gene expression from integration-deficient lentiviral vectors in the spinal cord.

Gene transfer to spinal cord cells may be crucial for therapy in spinal muscular atrophy, amyotrophic lateral sclerosis and spinal cord injury. Lentiviral vectors are efficient for transduction of a variety of cells, but like all integrating vectors they pose a risk of insertional mutagenesis. Integration-deficient lentiviral vectors (IDLVs) remain episomal but retain the transduction efficiency of standard integrating lentiviral vectors, particularly when the episomes are not diluted out through repeated cell division. We have now applied IDLVs for transduction of spinal cord in vitro, in explants and in vivo. Our results demonstrate similar efficiency of eGFP expression from integrating lentiviral vectors and IDLVs in most cell types analyzed, including motor neurons, interneurons, dorsal root ganglia (DRG) neurons and astroglia. IDLV-mediated expression of pro-glial-cell-derived neurotrophic factor (Gdnf) rescues motor neuron cultures from death caused by removal of exogenous trophic support. IDLVs also mediate efficient RNA interference in DRG neuron cultures. After intraparenchymal injection in the rat and mouse cervical and lumbar regions in vivo, transduction is mainly neuronal, with both motor neurons and interneurons being efficiently targeted. These results suggest that IDLVs could be efficient and safer tools for spinal cord transduction in future therapeutic strategies.

Corticospinal tract transduction: a comparison of seven adeno-associated viral vector serotypes and a non-integrating lentiviral vector.

The corticospinal tract (CST) is extensively used as a model system for assessing potential therapies to enhance neuronal regeneration and functional recovery following spinal cord injury (SCI). However, efficient transduction of the CST is challenging and remains to be optimised. Recombinant adeno-associated viral (AAV) vectors and integration-deficient lentiviral vectors are promising therapeutic delivery systems for gene therapy to the central nervous system (CNS). In the present study the cellular tropism and transduction efficiency of seven AAV vector serotypes (AAV1, 2, 3, 4, 5, 6, 8) and an integration-deficient lentiviral vector were assessed for their ability to transduce corticospinal neurons (CSNs) following intracortical injection. AAV1 was identified as the optimal serotype for transducing cortical and CSNs with green fluorescent protein (GFP) expression detectable in fibres projecting through the dorsal CST (dCST) of the cervical spinal cord. In contrast, AAV3 and AAV4 demonstrated a low efficacy for transducing CNS cells and AAV8 presented a potential tropism for oligodendrocytes. Furthermore, it was shown that neither AAV nor lentiviral vectors generate a significant microglial response. The identification of AAV1 as the optimal serotype for transducing CSNs should facilitate the design of future gene therapy strategies targeting the CST for the treatment of SCI.

Evaluation of a novel ECG lead placement method in telemetered freely moving cynomolgus monkeys: assessment of an intravascular biopotential lead.

INTRODUCTION: ECG is considered as a critical biomarker of cardiac safety pharmacology. ECG signal quality is essential for accurate interval quantification and automated arrhythmia detection. METHODS: We evaluated ECG signal quality over a 6 month period from 15 cynomolgus monkeys with radiotelemetry transmitters using biopotential leads where the negative lead was inserted in the jugular vein and advanced to the superior vena cava (intravascular lead) and the positive lead was placed on the diaphragm at the apex of the heart (diaphragmatic lead). Signal noise and signal-to-noise ratio from this implantation methodology were compared with signals obtained from animals with subcutaneous ECG lead. Macroscopic pathology and histopathology associated with the intravascular lead were evaluated at 6 months post-implantation in six monkeys. RESULTS: The ECG morphology obtained with the intravascular/diaphragmatic lead placement was comparable to conventional subcutaneous ECG (emulating Lead II) but presented higher amplitudes (P-wave +50.0%; R-wave +30.0%). Signal noise showed a circadian cycle of changes in magnitude for subcutaneous ECG leads that was not observed with this method. The intravascular/diaphragmatic lead placement presented a higher signal-to-noise ratio than subcutaneous ECG leads. No macroscopic abnormality was observed to be associated with the intravascular lead. Mild thickening of the intima/subintima with mild intimal proliferation of the cranial vena cava surrounding the intravascular lead were noted at histopathological examination. DISCUSSION: The intravascular/diaphragmatic ECG lead placement in cynomolgus monkeys provided reduced signal noise and elevated P-QRS-T amplitudes. The intravascular lead was well tolerated and appeared suitable for chronically instrumented cardiovascular safety pharmacology studies. Further assessments would be warranted to evaluate the potential of this methodology in other species.

Combined cardiopulmonary assessments with implantable telemetry device in conscious freely moving cynomolgus monkeys.

Female cynomolgus monkeys were surgically implanted with telemetry transmitters recording ECG (DII), arterial pressure, physical activity, body temperature, and tidal volume. Respiratory rate (RR) and tidal volume (TV) were monitored simultaneously with the telemetry transmitter using impedance. Impedance-based monitoring of RR and TV by telemetry correlated with controlled TV and with pneumotachometer (>98%) in restrained animals. Control drugs with cardiovascular and respiratory effects, including saline, medetomidine (0.01, 0.02 and 0.04mg/kg) and cocaine (0.5, 1.0 and 1.5mg/kg) were administered intravenously. An averaging epoch of 5min was used for analysis of respiratory data. Medetomidine induced significant respiratory depression with decrease in RR and TV in freely moving animals while cocaine increased TV, RR and minute ventilation (MV) with concomitant increase in heart rate when compared with time matched values from saline-treated animals. The onset, duration and magnitude of cardiovascular and respiratory changes were correlated. This highlights the dependency of the cardiovascular and respiratory systems. The use of cardiopulmonary monitoring can allow continuous monitoring including during night time when variability of respiratory parameters is lower. Monitoring of cardiovascular and respiratory parameters in the same animals could also help to decrease the number of animals used in research.

Australia's national trends in the incidence of Type 1 diabetes in 0-14-year-olds, 2000-2006.

AIMS: To determine the national incidence of Type 1 diabetes in children aged 0-14 years and examine trends in incidence between 2000 and 2006 by age, sex and calendar year. METHODS: Case ascertainment was from the Australian National Diabetes Register, a prospective population-based incidence register established in 1999, with two sources of ascertainment: the National Diabetes Services Scheme and the Australasian Paediatric Endocrine Group's state-based registers. Denominator data were from the Australian Bureau of Statistics. RESULTS: There were 6350 new cases of Type 1 diabetes (3323 boys and 3027 girls). Case ascertainment was 97.1% complete using the capture-recapture method. The mean adjusted incidence rate for 2000-2006 was 21.6 per 100,000 person-years [95% confidence interval (CI) 21.0, 22.1], and increased from 19.8 in 2000 to 23.4 per 100,000 in 2006, an average increase of 2.8% (95% CI 1.5, 4.1) per year. Mean incidence for the 7-year period increased with age, and was significantly higher in boys aged 0-4 years and 10-14 years than in girls of the same age. CONCLUSIONS: The incidence of Type 1 diabetes among 0-14-year-olds in Australia is very high compared with available data from many other countries. The rate of increase observed globally in the last decade has continued well into this decade in Australia. The rising incidence cannot be explained by changes in genetic susceptibility; there is an urgent need to examine the environmental factors that have contributed to this increase. The findings of this study also have important implications for resource planning.

Complement C5 regulates the expression of insulin-like growth factor binding proteins in chronic experimental allergic encephalomyelitis.

Complement activation plays a central role in autoimmune demyelination. To explore the possible effects of C5 on post-inflammatory tissue repair, we investigated the transcriptional profile induced by C5 in chronic experimental allergic encephalomyelitis (EAE) using oligonucleotide arrays. We used C5-deficient (C5-d) and C5-sufficient (C5-s) mice to compare the gene expression profile and we found that 390 genes were differentially regulated in C5-s mice as compared to C5-d mice during chronic EAE. Among them, a group of genes belonging to the family of insulin-like growth factor binding proteins (IGFBP) and transforming growth factor (TGF)-beta3 were found most significantly differentially regulated by C5. The dysregulation of these genes suggests that these proteins might be responsible for the gliosis and lack of remyelination seen in C5-d mice with chronic EAE.

Complement activation in autoimmune demyelination: dual role in neuroinflammation and neuroprotection.

Multiple sclerosis and its animal model experimental allergic encephalomyelitis are inflammatory demyelinating diseases of the central nervous system mediated by activated lymphocytes, macrophages/microglia and the complement system. Complement activation and the C5b-9 terminal complex contribute to the pathogenesis of these diseases through its role to promote demyelination. C5b-9 was also shown to protect oligodendrocytes from apoptosis both in vitro and in vivo. Our findings indicate that activation of complement and C5b-9 assembly plays a pro-inflammatory role in the acute phase, but may also be neuroprotective.

Neuronal overexpression of tissue-type plasminogen activator does not enhance sensory axon regeneration or locomotor recovery following dorsal hemisection of adult mouse thoracic spinal cord.

CNS axons rarely regenerate spontaneously back to original targets following spinal cord injury (SCI). Neuronal expression of the serine protease tissue-type plasminogen activator (tPA) enhances axon growth in vitro and following PNS injury. Here we test the hypothesis that neuronal overexpression of tPA in adult transgenic mice promotes CNS axon regeneration and functional recovery following SCI. Adult wild-type and transgenic mouse spinal cords were subjected to dorsal hemisection at the level of the T10/T11 vertebrae. PCR confirmed incorporation of the transgene. Immunolabeling revealed overexpression of tPA in transgenic mice in neurons, including large-diameter neurons in lumbar dorsal root ganglia that contribute axons to the dorsal columns. Immunolabeling also revealed the presence of tPA protein within axons juxtaposing the injury site in transgenics but not wild types. In situ zymography revealed abundant enzymatic activity of tPA in gray matter of thoracic spinal cords of transgenics but not wild types. Rotorod locomotor testing revealed no differences between groups in locomotor function up to 21 days postinjury. Transganglionic tracer was injected into the crushed right sciatic nerve 28 days postinjury, and mice were killed 3 days later. There was no evidence for regrowth of ascending dorsal column sensory axons through or beyond the injury site. In conclusion, despite neuronal overexpression of tPA in injured neurons of transgenics, neither locomotor recovery nor regeneration of ascending sensory axons was observed following thoracic dorsal hemisection.