High content analysis of in vitro alveolar macrophage responses can provide mechanistic insight for inhaled product safety assessment.

Assessing the safety of inhaled substances in the alveolar region of the lung requires an understanding of how the respired material interacts with both physical and immunological barriers. Human alveolar-like macrophages in vitro provide a platform to assess the immunological response in the airways and may better inform the understanding of a response to an inhaled challenge being adaptive or adverse. The aim of this study was to determine if a morphometric phenotyping approach could discriminate between different inhaled nicotine products and indicate the potential mechanism of toxicity of a substance. Cigarette smoke (CS) and e-liquids extracted into cell culture medium were applied to human alveolar-like macrophages in mono-culture (ImmuONE™) and co-culture (ImmuLUNG™) to test the hypothesis. Phenotype profiling of cell responses was highly reproducible and clearly distinguished the different responses to CS and e-liquids. Whilst the phenotypes of untreated macrophages were similar regardless of culture condition, macrophages cultured in the presence of epithelial cells were more sensitive to CS-induced changes related to cell size and vacuolation processes. This technique demonstrated phenotypical observations typical for CS exposure and indicative of the established mechanisms of toxicity. The technique provides a rapid screening approach to determine detailed immunological responses in the airways which can be linked to potentially adverse pathways and support inhalation safety assessment.

Survival and associated comorbidities in inclusion body myositis.

OBJECTIVE: To evaluate survival and associated comorbidities in inclusion body myositis (IBM) in a population-based, case-control study. METHODS: We utilized the expanded Rochester Epidemiology Project medical records-linkage system, including 27 counties in Minnesota and Wisconsin, to identify patients with IBM, other inflammatory myopathies (IIM), and age/sex-matched population-controls. We compared the frequency of various comorbidities and survival among groups. RESULTS: We identified 50 IBM patients, 65 IIM controls and 294 population controls. Dysphagia was most common in IBM (64%) patients. The frequency of neurodegenerative disorders (dementia/parkinsonism) and solid cancers was not different between groups. Rheumatoid arthritis was the most common rheumatic disease in all groups. A total of 36% of IBM patients had a peripheral neuropathy, 6% had Sjögren's syndrome and 10% had a haematologic malignancy. T-cell large granular lymphocytic leukaemia was only observed in the IBM group. None of the IBM patients had hepatitis B or C, or HIV. IBM patients were 2.7 times more likely to have peripheral neuropathy, 6.2 times more likely to have Sjögren's syndrome and 3.9 times more likely to have a haematologic malignancy than population controls. IBM was associated with increased mortality, with a 10-year survival of 36% from index, compared with 67% in IIM and 59% in population controls. Respiratory failure or pneumonia (44%) was the most common cause of death. CONCLUSIONS: IBM is associated with lower survival, and higher frequency of peripheral neuropathy, Sjögren's syndrome and haematologic malignancies than the general population. Close monitoring of IBM-related complications is warranted.

Incidence and disease burden of chemotherapy-induced peripheral neuropathy in a population-based cohort.

OBJECTIVE: To assess disease burden of chemotherapy-induced peripheral neuropathy (CIPN), which is a common dose-limiting side effect of neurotoxic chemotherapy. Late effects of CIPN may increase with improved cancer survival. METHODS: Olmsted County, Minnesota residents receiving neurotoxic chemotherapy were identified and CIPN was ascertained via text searches of polyneuropathy symptoms in the medical record. Clinical records were queried to collect data on baseline characteristics, risk factors, signs and symptoms of CIPN, medications, impairments and International Classification of Diseases, Ninth Revision (ICD-9) diagnostic codes for all subjects. RESULTS: A total of 509 individuals with incident exposure to an inclusive list of neurotoxic chemotherapy agents between 2006 and 2008 were identified. 268 (52.7%) of these individuals were determined to have CIPN. The median time from incident exposure to first documented symptoms was 71 days. Patients with CIPN received a neuropathy ICD-9 diagnosis in only 37 instances (13.8%). Pain symptoms and use of pain medications were observed more often in patients with CIPN. Five-year survival was greater in those with CIPN (55.2%) versus those without (36.1%). Those with CIPN surviving greater than 5 years (n=145) continued to have substantial impairments and were more likely to be prescribed opioids than those without CIPN (OR 2.0, 1.06-3.69). CONCLUSIONS: Results from our population-based study are consistent with previous reports of high incidence of CIPN in the first 2 years following incident exposure to neurotoxic chemotherapeutic agents, and its association with significant pain symptomatology and accompanied long-term opioid use. Increased survival following exposure to neurotoxic chemotherapy and its long-term disease burden necessitates further study among survivors.

Proximal myopathy with focal depletion of mitochondria and megaconial congenital muscular dystrophy are allelic conditions caused by mutations in CHKB.

We recently evaluated two of the original three patients (siblings) diagnosed with Proximal Myopathy with Focal Depletion of Mitochondria. The condition was named for the distinctive pattern of enlarged mitochondria around the periphery of muscle fibres with a complete absence in the middle. These siblings, aged 37 and 40, are cognitively normal with mild non-progressive muscle weakness and a susceptibility to rhabdomyolysis. Both were shown to be compound heterozygotes for novel mutations (c.263C>T + c.950T>A) in CHKB, the gene currently associated with Megaconial Congenital Muscular Dystrophy. Individuals with this condition have early-onset muscle weakness and profound intellectual disability but share the same unique pattern on muscle biopsy as was noted in Proximal Myopathy with Focal Depletion of Mitochondria; focal depletion of mitochondria was surrounded by abnormally large "megaconial" mitochondria. Thus the phenotypic spectrum of CHKB mutations ranges from a congenital muscular dystrophy with intellectual disability to a later-onset non-progressive muscular weakness with normal cognition.

French Osteotomy for Cubitus Varus in Children: A Long-term Study Over 27 Years.

BACKGROUND: Cubitus varus is a cosmetically unacceptable complication of supracondylar fractures of the elbow in children. We have performed the lateral closing wedge (French) osteotomy to correct the varus for 27 years. More complex osteotomies have been described to correct the associated hyperextension and internal rotation deformities and to prevent a prominent lateral condyle. METHODS: We retrospectively reviewed 90 consecutive patients (1986 to 2012). The mean age of the patients at surgery was 8.2 years (3 to 14 y). The varus angle (mean, 21.4 degrees; range, 8 to 40 degrees) was assessed preoperatively with the humero-elbow-wrist angle. The postoperative carrying angle (mean, 10.4 degrees) and the preoperative and postoperative range of movement were assessed clinically. The lateral condylar prominence index (LCPI) was retrospectively measured at union. RESULTS: Eighty-four (93.3%) of the patients had a good or excellent result. Six (6.7%) had a poor result (residual varus, loss of >20 degrees of preoperative range of flexion or extension or a complication necessitating resurgery). There were no neurovascular complications. The mean LCPI was +0.14. CONCLUSIONS: The results of the French osteotomy are comparable with the more technically demanding dome, step-cut translation, and multiplanar osteotomies, with a lower complication rate. The literature reports adequate remodeling of the hyperextension deformity (≤10 y) and the LCPI (≤12 y), and that the internal rotation deformity is well tolerated by the patient. LEVEL OF EVIDENCE: Level IV-case series.

Alpha-sarcoglycanopathy presenting as exercise intolerance and rhabdomyolysis in two adults.

Two patients with exercise-induced myalgias and rhabdomyolysis with myoglobinuria were evaluated with muscle biopsy and comprehensive myopathy next generation sequencing (NGS) gene panels. Genetic analysis revealed homozygosity for two known pathogenic SGCA mutations (R284C in Patient 1 and V247M in Patient 2). Muscle biopsy showed minimal changes with normal immunohistochemistry for α-sarcoglycan. Western blotting showed 27% and 35% of normal α-sarcoglycan immunoreactivity when compared to age matched controls, confirming the diagnosis of α-sarcoglycanopathy in both patients. The sarcoglycan genes should be added to the differential diagnosis for cases that present with rhabdomyolysis, exercise intolerance, and hyperCKemia, even in the absence of muscle weakness or normal α-sarcoglycan immunohistochemistry. Work-up of patients with these types of non-specific presentation may be best facilitated through the use of non-specific NGS myopathy panels.

Interictal scalp electroencephalography and intraoperative electrocorticography in magnetic resonance imaging-negative temporal lobe epilepsy surgery.

IMPORTANCE: Scalp electroencephalography (EEG) and intraoperative electrocorticography (ECoG) are routinely used in the evaluation of magnetic resonance imaging-negative temporal lobe epilepsy (TLE) undergoing standard anterior temporal lobectomy with amygdalohippocampectomy (ATL), but the utility of interictal epileptiform discharge (IED) identification and its role in outcome are poorly defined. OBJECTIVES: To determine whether the following are associated with surgical outcomes in patients with magnetic resonance imaging-negative TLE who underwent standard ATL: (1) unilateral-only IEDs on preoperative scalp EEG; (2) complete resection of tissue generating IEDs on ECoG; (3) complete resection of opioid-induced IEDs recorded on ECoG; and (4) location of IEDs recorded on ECoG. DESIGN, SETTING, AND PARTICIPANTS: Data were gathered through retrospective medical record review at a tertiary referral center. Adult and pediatric patients with TLE who underwent standard ATL between January 1, 1990, and October 15, 2010, were considered for inclusion. Inclusion criteria were magnetic resonance imaging-negative TLE, standard ECoG performed at the time of surgery, and a minimum follow-up of 12 months. Univariate analysis was performed using log-rank time-to-event analysis. Variables reaching significance with log-rank testing were further analyzed using Cox proportional hazards. MAIN OUTCOMES AND MEASURES: Excellent or nonexcellent outcome at time of last follow-up. An excellent outcome was defined as Engel class I and a nonexcellent outcome as Engel classes II through IV. RESULTS: Eighty-seven patients met inclusion criteria, with 48 (55%) achieving an excellent outcome following ATL. Unilateral IEDs on scalp EEG (P = .001) and complete resection of brain regions generating IEDs on baseline intraoperative ECoG (P = .02) were associated with excellent outcomes in univariate analysis. Both were associated with excellent outcomes when analyzed with Cox proportional hazards (unilateral-only IEDs, relative risk = 0.31 [95% CI, 0.16-0.64]; complete resection of IEDs on baseline ECoG, relative risk = 0.39 [95% CI, 0.20-0.76]). Overall, 25 of 35 patients (71%) with both unilateral-only IEDs and complete resection of baseline ECoG IEDs had an excellent outcome. CONCLUSIONS AND RELEVANCE: Unilateral-only IEDs on preoperative scalp EEG and complete resection of IEDs on baseline ECoG are associated with better outcomes following standard ATL in magnetic resonance imaging-negative TLE. Prospective evaluation is needed to clarify the use of ECoG in tailoring temporal lobectomy.

Activated MHC-mismatched T helper-1 lymphocyte infusion enhances GvL with limited GvHD.

DLI is traditionally used to provide graft-versus-leukemia (GvL) effects when given to patients relapsing post-hematopoietic cell transplantation (HCT). However, it is often associated with significant GvHD and has only modest efficacy against acute leukemias. Therefore, novel cellular therapies are needed to improve the outcome of high-risk or relapsed leukemia patients following HCT. Activated T helper-1 (aTh-1) lymphocytes are CD4(+)CD25(+)CD40L(+)CD62L(lo) effector memory cells that produce large amounts of IFN-γ and TNF-α. We demonstrate that post-transplant adoptive aTh-1 cell therapy enhances GvL with limited GvHD in an MHC-mismatched murine BMT model. aTh-1 infusions result in superior leukemia-free survival when compared with unstimulated splenocytes (SC), purified CD4(+) T-cells and T-cell-enriched SC. aTh-1 cells display cytotoxicity against A20 leukemia cells in vitro and persist in vivo for at least 2 months following adoptive transfer. Furthermore, in contrast to unstimulated SC, aTh-1 cell infusion is associated with only transient, mild suppression of donor-derived hematopoiesis. aTh-1 cell therapy is safe, effective and warrants further investigation as an alternative to DLI.

[MED12 gene mutations in women with uterine myoma].

Uterine leiomyoma (UL) is a benign and most common tumor that affects 20-45% of women of fertile age. In this study, we analyzed the MED12 second exon nucleotide sequence from 15 DNA samples extracted from LM of 15 subjects with uterine leiomyoma and 15 DNA samples extracted from peripheral blood leukocytes of the same female subjects. It was shown that somatic mutations in the MED12 gene occur in 73% of cases with deletions of varying sizes and missense mutations being most common at codon 44. Mutations in the MED12 gene could play an indirect role in leiomyoma progression by modifying the activity of other genes that encode proteins involved in growth and tumor progression.

Quantitative assessment of chronic lung disease of infancy using computed tomography.

The aims of this study were to determine whether infants and toddlers with chronic lung disease of infancy (CLDI) have smaller airways and lower lung density compared with full-term healthy controls. Multi-slice computed tomography (CT) chest scans were obtained at elevated lung volumes during a brief respiratory pause in sedated infants and toddlers; 38 CLDI were compared with 39 full-term controls. For CLDI subjects, gestational age at birth ranged from 25 to 29 weeks. Airway size was measured for the trachea and the next three to four generations into the right lower lobe; lung volumes and tissue density were also measured. The relationship between airway size and airway generation differed between the CLDI and full-term groups; the sizes of the first and second airway generations were larger in the shorter CLDI than in the shorter full-term subjects. The increased size in the airways in the CLDI subjects was associated with increasing mechanical ventilation time in the neonatal period. CLDI subjects had a greater heterogeneity of lung density compared with full-term subjects. Our results indicate that quantitative analysis of multi-slice CT scans at elevated volumes provides important insights into the pulmonary pathology of infants and toddlers with CLDI.

Subclinical atherosclerosis, airflow obstruction and emphysema: the MESA Lung Study.

Airflow obstruction is an independent risk factor for cardiovascular events in the general population. The affected vascular bed and contribution of emphysema to cardiovascular risk are unclear. We examined whether an obstructive pattern of spirometry and quantitatively defined emphysema were associated with subclinical atherosclerosis in the carotid, peripheral and coronary circulations. The Multi-Ethnic Study of Atherosclerosis recruited participants aged 45-84 yrs without clinical cardiovascular disease. Spirometry, carotid intima-media thickness (IMT), ankle-brachial index (ABI) and coronary artery calcium (CAC) were measured using standard protocols. Percentage of emphysema-like lung was measured in the lung windows of cardiac computed tomography scans among 3,642 participants. Multiple linear regression was used to adjust for cardiac risk factors, including C-reactive protein. Decrements in forced expiratory volume in 1 s (FEV(1)) and FEV(1)/forced vital capacity ratio were associated with greater internal carotid IMT, particularly among smokers (p=0.03 and p<0.001, respectively) whereas percentage emphysema was associated with reduced ABI regardless of smoking history (p=0.004). CAC was associated with neither lung function (prevalence ratio for the presence of CAC in severe airflow obstruction 0.99, 95% CI 0.91-1.07) nor percentage emphysema. An obstructive pattern of spirometry and emphysema were associated distinctly and independently with subclinical atherosclerosis in the carotid arteries and peripheral circulation, respectively, and were not independently related to CAC.

The effect of percutaneous pin fixation in the treatment of distal femoral physeal fractures.

Distal femoral physeal fractures in children have a high incidence of physeal arrest, occurring in a mean of 40% of cases. The underlying nature of the distal femoral physis may be the primary cause, but other factors have been postulated to contribute to the formation of a physeal bar. The purpose of this study was to assess the significance of contributing factors to physeal bar formation, in particular the use of percutaneous pins across the physis. We reviewed 55 patients with a median age of ten years (3 to 13), who had sustained displaced distal femoral physeal fractures. Most (40 of 55) were treated with percutaneous pinning after reduction, four were treated with screws and 11 with plaster. A total of 40 patients were assessed clinically and radiologically after skeletal maturity or at the time of formation of a bar. The remaining 15 were followed up for a minimum of two years. Formation of a physeal bar occurred in 12 (21.8%) patients, with the rate rising to 30.6% in patients with high-energy injuries compared with 5.3% in those with low-energy injuries. There was a significant trend for physeal arrest according to increasing severity using the Salter-Harris classification. Percutaneous smooth pins across the physis were not statistically associated with growth arrest.

Exploration of the volumetric composition of human lung cancer nodules in correlated histopathology and computed tomography.

Gaining a complete and comprehensive understanding of lung cancer nodule histological compositions and how these tissues are represented in radiological data is important not only for expanding the current knowledge base of cancer growth and development but also has potential implications for classification standards, radiological diagnosis methods and for the evaluation of treatment response. In this study we generate large scale histological segmentations of the cancerous and non-cancerous tissues within resected lung nodules. We have implemented a processing pipeline which allows for the direct correlation between histological data and spatially corresponding computed tomography data. Utilizing these correlated datasets we evaluated the statistical separation between Hounsfield Unit (HU) histogram values for each tissue type. The findings of this study revealed that lung cancer nodules contain a complex intermixing of cellular tissue types and that trends exist in the relationship between these tissue types. It was found that the mean Hounsfield Unit values for isolated lung cancer nodules imaged with computed tomography, had statistically significantly different values for non-solid bronchoalveolar carcinoma, solid cancerous tumor, blood, and inactive fibrotic stromal tissue.

Evaluation of tumorigenic risk of tissue-engineered oral mucosal epithelial cells by using combinational examinations.

Recently, oral mucosal epithelial cells were proposed as a cell source of the autologous cell transplant therapy for corneal trauma or disease. The question addressed is to know if the biological conditions of grafting could induce certain cellular, molecular, and genetic alterations that might increase the risk of mutations and possibly of cellular transformation. Recent progress in cancer research enables us to depict the generation mechanisms and basic characteristics of human cancer cells from molecular, cytological, and biological aspects. The aim of this study is to evaluate the risk of tumorigenicity of the oral mucosal epithelial culture process in order to mitigate that risk, if any, before clinical application. Oral mucosal epithelial cells from three different human donors were investigated by combinational examinations to detect possible tumorigenic transformation. We investigated (i) clonogenic and karyology types, (ii) the validation of proliferation rate, (iii) the epithelial-mesenchymal transition, (iv) anchorage-independent growth potential, and (v) tumorigenicity on nude mice. Results show that the culture process used in this study presents no risk of tumorigenicity.

Role of aquaporin-1 in trabecular meshwork cell homeostasis during mechanical strain.

Aquaporin-1 (AQP1) channels are expressed by trabecular meshwork (TM) and Schlemm's canal cells of the conventional outflow pathway where fluid movement is predominantly paracellular, suggesting a non-canonical role for AQP1. We hypothesized that AQP1 functions to protect TM cells during periods of mechanical strain. To test this idea, primary cultures of confluent human TM cells on Bioflex membranes were exposed to static and cyclic stretch for 8 and 24h using the Flexcell system. AQP1 expression in TM cells was assessed by SDS-PAGE and Western blot using anti-AQP1 IgGs. AQP1 protein bands were analyzed using densitometry and normalized to beta-actin expression. Cell damage was monitored by measuring lactate dehydrogenase (LDH) and histone deacetylase appearance in conditioned media. Recombinant expression of AQP1 in TM cell cultures was facilitated by transduction with adenovirus. Results show that AQP1 expression significantly increased 2-fold with 10% static stretch and 3.5-fold with 20% static stretch at 8h (n=4, p<0.05) and 24h (n=6, p<0.05). While histone deacetylase levels were unaffected by treatments, release of LDH from TM cells was the most profound at the 20% static stretch level (n=4, p<0.05). Significantly, cells were refractory to the 20% static stretch level when AQP1 expression was increased to near tissue levels. Analysis of LDH release with respect to AQP1 expression revealed an inverse linear relationship (r(2)=0.7780). Taken together, AQP1 in human TM appears to serve a protective role by facilitating improved cell viability during conditions of mechanical strain.

Decreased platelet expression of myosin regulatory light chain polypeptide (MYL9) and other genes with platelet dysfunction and CBFA2/RUNX1 mutation: insights from platelet expression profiling.

We have reported on a patient with thrombocytopenia, impaired platelet aggregation, secretion, phosphorylation of pleckstrin and myosin light chain (MLC), and GPIIb-IIIa activation, associated with a heterozygous mutation in transcription factor CBFA2 (core binding factor A2, RUNX1 or AML1). To obtain insights into the abnormal platelet mechanisms and CBFA2-regulated genes, we performed platelet expression profiling in four control subjects and the patient using the Affymetrix U133 GeneChips. In the patient, 298 probe sets were significantly downregulated at least 2-fold. MLC regulatory polypeptide (MYL9 gene) was decreased approximately 77-fold; this is an important finding because agonist-stimulated MLC phosphorylation is decreased in patient platelets. Genes downregulated > or = 5-fold include those involving calcium binding proteins (CABP5), ion transport (sodium/potassium/Ca exchanger, SLC24A3), cytoskeletal/microtubule proteins (erythrocyte membrane protein band 4.1-like 3, EPB41L3; tropomyosin 1, TPM1; tubulin, alpha 1, TUBA1), signaling proteins (RAB GTPase activating protein 1-like, RABGAP1L; beta3-endonexin, ITGB3 BP) and chemokines (platelet factor 4 variant 1, PF4V1; chemokine CXCL5, CXCL5). These and other downregulated genes are relevant to the patient's platelet defects in function and production. These studies provide the first proof of concept that platelet expression profiling can be applied to obtain insights into the molecular basis of inherited platelet defects.

Myocilin-associated exosomes in human ocular samples.

Mutations in myocilin result in ocular hypertension, likely due to decreased drainage of aqueous humor through the trabecular meshwork. Since less myocilin is found in the aqueous humor of those with disease-causing mutations, understanding myocilin's role in the aqueous humor is of clinical importance. Recently, myocilin was shown to exit cultured trabecular meshwork cells in association with shed vesicles called exosomes. To examine relevance of this finding in a physiological setting, the present study examined three different types of ocular samples for the presence of myocilin-associated exosomes. Using differential centrifugation steps, we found myocilin associated with exosomes isolated from effluent collected from human anterior segments in organ culture and aqueous humor obtained from human cadaveric eyes or from patients undergoing excisional surgery. Similar to results with cultured cells, myocilin associated predominately with exosomes in fresh samples, appeared mostly soluble at later times, and had biochemical properties (density of 1.13-1.19 g/ml in linear sucrose gradient) similar to those characteristics of exosomes. These data indicate that exosomes are present and may facilitate the transport of myocilin into the extracellular space of human ocular cells.

Recombinant NY-ESO-1 cancer antigen: production and purification under cGMP conditions.

The cancer-testis antigen, NY-ESO-1, has been engineered into a bacterial expression plasmid which incorporates a His6-tag. The plasmid was transfected into E. coli strain BL21 and Master and Working cell banks generated from this expression system. Three 15-litre fermentations were performed under cGMP (code of Good Manufacturing Practice) conditions and the crude NY-ESO-1 tagged protein isolated as solubilised inclusion bodies. A three-step cGMP chromatography process (immobilised metal affinity, anion exchange, and hydrophobic interaction) was utilised to purify the protein. The purified NY-ESO-1 is being used in early stage human cancer vaccine trials in Australia and the U.S.A.

Double-elevating osteotomy for late-presenting infantile Blount's disease: the importance of concomitant lateral epiphysiodesis.

We reviewed 34 knees in 24 children after a double-elevating osteotomy for late-presenting infantile Blount's disease. The mean age of patients was 9.1 years (7 to 13.5). All knees were in Langenskiöld stages IV to VI. The operative technique corrected the depression of the medial joint line by an elevating osteotomy, and the remaining tibial varus and internal torsion by an osteotomy just below the apophysis. In the more recent patients (19 knees), a proximal lateral tibial epiphysiodesis was performed at the same time. The mean pre-operative angle of depression of the medial tibial plateau of 49 degrees (40 degrees to 60 degrees ) was corrected to a mean of 26 degrees (20 degrees to 30 degrees ), which was maintained at follow-up. The femoral deformity was too small to warrant femoral osteotomy in any of our patients. The mean pre-operative mechanical varus of 30.6 degrees (14 degrees to 66 degrees ) was corrected to 0 degrees to 5 degrees of mechanical valgus in 29 knees. In five knees, there was an undercorrection of 2 degrees to 5 degrees of mechanical varus. At follow-up a further eight knees, in which lateral epiphysiodesis was delayed beyond five months, developed recurrent tibial varus associated with fusion of the medial proximal tibial physis.

Three-dimensional path planning for virtual bronchoscopy.

Multidetector computed-tomography (MDCT) scanners provide large high-resolution three-dimensional (3-D) images of the chest. MDCT scanning, when used in tandem with bronchoscopy, provides a state-of-the-art approach for lung-cancer assessment. We have been building and validating a lung-cancer assessment system, which enables virtual-bronchoscopic 3-D MDCT image analysis and follow-on image-guided bronchoscopy. A suitable path planning method is needed, however, for using this system. We describe a rapid, robust method for computing a set of 3-D airway-tree paths from MDCT images. The method first defines the skeleton of a given segmented 3-D chest image and then performs a multistage refinement of the skeleton to arrive at a final tree structure. The tree consists of a series of paths and branch structural data, suitable for quantitative airway analysis and smooth virtual navigation. A comparison of the method to a previously devised path-planning approach, using a set of human MDCT images, illustrates the efficacy of the method. Results are also presented for human lung-cancer assessment and the guidance of bronchoscopy.