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Biomedical subjects

Shaf Keshavjee

Publications and source records attributed to Shaf Keshavjee.

At least 19 recordsLinked to original sources
PubMed2007

Impact of lymph node metastasis on outcome after extrapleural pneumonectomy for malignant pleural mesothelioma.

OBJECTIVES: Extrapleural pneumonectomy is a therapeutic option for selected patients with malignant pleural mesothelioma. The impact of lymph node metastasis on the site of recurrence and the role of mediastinoscopy in the selection of patients for extrapleural pneumonectomy, however, remain unclear. METHODS: We reviewed 50 consecutive patients undergoing extrapleural pneumonectomy for malignant pleural mesothelioma in our institution between January 1993 and March 2005. RESULTS: The median survival was 11 months, with a 3-year survival of 24%. Survival was significantly worse for patients with N2 disease than for those with no lymph node metastasis (median survival 10 months vs 29 months, respectively, P = .005). Patient sex, histologic cell type, stage, and N2 disease, but not mediastinoscopy, had significant impacts on survival according to univariate analysis. In a multivariate analysis, however, only the presence of N2 disease remained a significant predictor of poor outcome. The proportion of patients with N2 disease and the long-term survival was similar regardless of whether preoperative mediastinoscopy yielded a negative result. The initial site of recurrence was determined in 28 patients (locoregional in 10 and distant in 18). The presence of N2 disease had no impact on the site of recurrence. Adjuvant hemithoracic radiation therapy, however, significantly decreased the risk of locoregional recurrence. CONCLUSIONS: The presence of N2 disease negatively affects the prognosis of patients with malignant pleural mesothelioma. Mediastinoscopy, however, seems to have a limited role in patient selection for extrapleural pneumonectomy. Adjuvant hemithoracic radiation therapy but not N2 disease affects the risk of locoregional recurrence.

Adult↗
PubMed2006

Cell-based tissue engineering for lung regeneration.

Emphysema is a chronic lung disease characterized by alveolar enlargement and tissue loss. Tissue engineering represents an attractive potential for regeneration of several organ systems. The complex three-dimensional architectural structure of lung parenchyma requiring connections of alveolar units to airways and the pulmonary circulation makes this strategy less optimistic. In the present study, we used Gelfoam sponge as a scaffold material, supplemented with fetal rat lung cells as progenitors, to explore the potential application of cell-based tissue engineering for lung regeneration in adult rats. After injection into lung parenchyma, the sponge showed porous structures similar to alveolar units. It did not induce severe local inflammatory response. Fetal lung cells in the sponge were able to survive in the adult lung for at least 35 days, determined by CMTMR [5-(and-6)-{[(4-chloromethyl)benzoyl]amino}tetramethylrhodamine] labeling. Proliferation of cells within the sponge was demonstrated in vivo by bromodeoxyuridine (BrdU) labeling. Cells formed "alveolar-like structures" at the border between the sponge and the surrounding lung tissue with positive immunohistochemical staining for epithelial and endothelial cells. Neovascularization of the sponge was demonstrated with India ink perfusion. The sponge degraded after several months. This study suggests that cell-based tissue engineering possesses the potential to regenerate alveolar-like structures, an important step towards our ultimate goal of lung regeneration.

Absorbable Implants↗
PubMed2006

High-volume ventilation induces pentraxin 3 expression in multiple acute lung injury models in rats.

Pentraxin 3 (PTX3) is an acute-phase protein, which can be produced by a variety of tissue cells at the site of infection or inflammation. It plays an important role in innate immunity in the lung and in mediating acute lung injury. The aim of this study was to determine the effect of mechanical ventilation on PTX3 expression in multiple lung injury models. Male Sprague-Dawley rats were challenged with intravenous injection of lipopolysaccharide (LPS) or hemorrhage followed by resuscitation (HS). The animals were then subjected to either relatively higher (12 ml/kg) or lower (6 ml/kg, positive end-expiratory pressure of 5 cmH(2)O) volume ventilation for 4 h. High-volume ventilation significantly enhanced PTX3 expression in the lung, either alone or in combination with LPS or hemorrhage. A significant increase of PTX3 immunohistochemistry staining in the lung was seen in all injury groups. The PTX3 expression was highly correlated with the severity of lung injury determined by blood gas, lung elastance, and wet-to-dry ratio. To determine the effects of HS, LPS, or injurious ventilation (25 ml/kg) alone on PTX3 expression, another group of rats was studied. Injurious ventilation significantly damaged the lung and increased PTX3 expression. A local expression of PTX3 induced by high-volume ventilation, either alone or in combination with other pathological conditions, suggests that it may be an important mediator in ventilator-induced lung injury.

Acute Disease↗
PubMed2006

The effect of gender combinations on outcome in human lung transplantation: the International Society of Heart and Lung Transplantation Registry experience.

BACKGROUND: In the current practice of lung transplantation, donor and recipient genders are neither directly considered nor matched. METHODS: We analyzed the potential effect of gender combinations on survival in 9,651 lung transplant recipients in the International Society of Heart and Lung Transplantation Registry (ISHLT) Registry. We compared the risk of overall and 90-day mortality by using statistical models that accounted for confounding variables. RESULTS: A Kaplan-Meier survival analysis revealed a significant difference of survival among gender combinations (log rank, p = 0.0009). The unadjusted odds ratio (OR) of 90-day mortality was significantly higher in female (F) donors to male (M) recipients (OR, 1.58; 95% confidence interval (CI), 1.22-2.04; p < 0.001) and lower in F to F (OR, 0.742; 95% CI, 0.61-0.90; p = 0.004) compared with the reference category of M to M. After adjusting for size mismatch and diagnosis in the multivariate logistic regression model, the OR of F to M was still statistically significant (F to M OR, 1.52l; 95% CI, 1.04-2.20; p = 0.028; F to F OR, 0.67; 95% CI, 0.53-0.91; p = 0.008) for 90-day mortality. A Cox proportional hazards analysis for overall survival also showed a significantly higher hazard ratio of 1.12 in F to M (95% CI, 1.01-1.23) and a lower hazard ratio of 0.92 in F to F (95% CI, 0.87-0.98). CONCLUSION: ISHLT Lung Transplant Registry data demonstrated a significant risk for F to M. Interestingly, F to F appears to be potentially beneficial in lung transplantation. Gender combinations do appear to significantly impact outcome after lung transplantation.

Adult↗
PubMed2006

Absence of typical unfolded protein response in primary cultured cystic fibrosis airway epithelial cells.

We examined whether the unfolded protein response is activated in cells expressing incorrectly folded cystic fibrosis transmembrane conductance regulator. Airway epithelial cells from three control and three CF patients homozygous for the deltaF508 mutation were tested. There were no differences in protein expression of the pro-apoptotic factor C/EBP homologous protein (CHOP) or the endoplasmic reticulum (ER) chaperone binding Ig protein. Nor were there differences in phosphorylation of protein kinase R-like ER kinase or eukaryotic initiation factor-2alpha, or the splicing of X-box binding protein (XBP)-1. However, CF cells showed increased mRNA expression of CHOP and XBP-1. A proteasome inhibitor increased CHOP expression in CF cells, suggesting that enhanced proteasome activation is responsible for the observed post-transcriptional regulation. Finally, CF cells were resistant to apoptosis, suggesting that post-transcriptional regulation of CHOP prevents apoptosis. While CHOP and XBP-1 mRNA expression is increased in CF cells, the classic UPR is not present.

Activating Transcription Factor 6↗
PubMed2006

Non-utilization of hearts and lungs after consent for donation: a Canadian multicentre study.

PURPOSE: To identify reasons why hearts and lungs from consented adult organ donors are not transplanted and identify changes in practice aimed at increasing their utilization rates. A greater potential may exist in Canada to improve utilization rates for hearts and lungs given their comparatively suboptimal rates (kidneys 85%, livers 84%, hearts 35% and lungs 23% reported in 2001). METHODS: Four Canadian organ procurement organizations participated. All adult organ donation cases for the calendar year 2002 were reviewed and included if consent for organ donation was obtained. An organ donation framework was established to highlight key areas where organs are lost from the transplantation stream. Organ donor cases were analyzed through this framework. RESULTS: A utilization rate of 39% (42/107) for heart and 28% (29/105) for lung donors was found, comparable to Canadian and international rates. Organ function was the most frequently cited reason for non-utilization, followed by donor characteristics and logistical issues. Suggestions for alternate management, potentially resulting in organ utilization, were made in 20 of 65 (31%) hearts and 28 of 156 (18%) lungs. Variable practices, around consent for individual organs and offering of organs consented, remained significant barriers to successful transplantation. CONCLUSION: Target areas for changes in practice included consenting and offering of all organs. Management of "marginal" organs should include resuscitation and reevaluation thus allowing potential organ rescue and utilization. Although there is considerable pressure to increase organs for transplantation, any such mechanism will not be judged successful unless recipient graft survival rates remain acceptable.

Adult↗
PubMed2006

Mycobacterium abscessus infections in lung transplant recipients: the international experience.

BACKGROUND: The clinical significance of Mycobacterium abscessus infection in the lung transplant population is not well understood. METHODS: An international survey was performed to determine the incidence and clinical outcomes of M abscessus infections before and after lung transplantation. RESULTS: Thirty-one (50%) of the 62 transplant centers affiliated with the International Society of Heart and Lung Transplantation responded to the survey. Of 5,200 transplants performed, 17 patients (0.33%) (M/F, 12:5) were identified with M abscessus after transplantation. Two patients had respiratory colonization before lung transplantation. Post-transplantation M abscessus infections occurred in the pulmonary allograft in 12, in skin/soft tissue in 3, or both in 2. Median time to diagnosis after transplantation was 18.5 months (range, 1-111 months). Therapies included multiple antibiotics in 16, surgical débridement in 2, interferon-gamma in 1, or no therapy owing to presumed colonization in 1. Eleven (73%) of 16 treated patients had a radiologic or microbiologic response to treatment. Concurrent infections were common, with Aspergillus (n = 8) and Pseudomonas aeruginosa (n = 5) most frequently seen. Death in 2 patients was attributed to M abscessus. Ten of 17 patients are alive and considered cured. CONCLUSIONS: M abscessus infection in the lung transplant recipient is uncommon and challenging; however, successful treatment can occur. Prolonged combination anti-microbial therapy is required for pulmonary involvement, and surgical débridement is recommended for cutaneous lesions. Concurrent infections are common and may contribute to mortality in this immunosuppressed population.

Adult↗
PubMed2006

Toll-like receptor and cytokine gene expression in the early phase of human lung transplantation.

BACKGROUND: Innate immunity is the first line of host defense against invading microorganisms, which is mediated by specific pathogen recognition molecules called toll-like receptors (TLRs). TLRs can also recognize endogenous "danger" signals, resulting in cytokine production and activation of the adaptive immune system. We hypothesized that gene expression of TLRs during lung transplantation may be affected by the donor condition and the ischemia-reperfusion process, which may subsequently influence graft function. METHODS: Lung biopsies from 14 patients were collected before and after reperfusion, and mRNA levels of TLRs, cytokines (interleukin [IL]-1beta, IL-6, IL-8, IL-10 and interferon-gamma) and heat-shock protein 70 (HSP70) were measured by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In cold-preserved donor lungs, all TLRs (except TLR3) showed significant correlations with one another and also with the cytokines examined. Expression of several TLRs and cytokines correlated with the intubation time of donors. TLR4 gene expression correlated closely with IL-8 before and after reperfusion (p </= 0.01). After reperfusion, HSP70 mRNAs increased significantly (p < 0.05). CONCLUSIONS: Differential expression levels of TLRs and cytokine genes likely reflect the inflammatory status of lung grafts; correlation of TLR genes with cytokine genes and clinical conditions implicates a potential role of TLRs in early graft responses.

Adult↗
PubMed2006

The early responses of VEGF and its receptors during acute lung injury: implication of VEGF in alveolar epithelial cell survival.

INTRODUCTION: The function of the vascular endothelial growth factor (VEGF) system in acute lung injury (ALI) is controversial. We hypothesized that the role of VEGF in ALI may depend upon the stages of pathogenesis of ALI. METHODS: To determine the responses of VEGF and its receptors during the early onset of ALI, C57BL6 mice were subjected to intestinal ischemia or sham operation for 30 minutes followed by intestinal ischemia-reperfusion (IIR) for four hours under low tidal volume ventilation with 100% oxygen. The severity of lung injury, expression of VEGF and its receptors were assessed. To further determine the role of VEGF and its type I receptor in lung epithelial cell survival, human lung epithelial A549 cells were treated with small interference RNA (siRNA) to selectively silence related genes. RESULTS: IIR-induced ALI featured interstitial inflammation, enhancement of pulmonary vascular permeability, increase of total cells and neutrophils in the bronchoalveolar lavage (BAL), and alveolar epithelial cell death. In the BAL, VEGF was significantly increased in both sham and IIR groups, while the VEGF and VEGF receptor (VEGFR)-1 in the lung tissues were significantly reduced in these two groups. The increase of VEGF in the BAL was correlated with the total protein concentration and cell count. Significant negative correlations were observed between the number of VEGF or VEGFR-1 positive cells, and epithelial cells undergoing cell death. When human lung epithelial A549 cells were pre-treated with 50 nM of siRNA either against VEGF or VEGFR-1 for 24 hours, reduced VEGF and VEGFR-1 levels were associated with reduced cell viability. CONCLUSION: These results suggest that VEGF may have dual roles in ALI: early release of VEGF may increase pulmonary vascular permeability; reduced expression of VEGF and VEGFR-1 in lung tissue may contribute to the death of alveolar epithelial cells.

Animals↗
PubMed2006

Gene therapy in lung transplantation.

Lung transplantation is effective life-saving therapy for the treatment of a variety of end-stage lung diseases. However, the application of lung transplantation is hindered by multiple factors such as the shortage of organ donors, early graft failure and chronic graft dysfunction. These problems are related to various lung injuries before and after transplantation including donor brain-death-related lung injury, ischemia, reperfusion and immune-mediated injuries. Gene transfection presents a potential molecular therapeutic solution to modify the transplanted organ such that it is better able to deal with these obstacles. In fact, in many ways lung transplantation is an ideal situation for gene therapy in that: 1) the targeted injuries are predictable (e.g. IR injury), 2) only transient gene expression is needed in many instances, 3) the immunosuppressive regimen necessary to prevent rejection of the transplanted organ attenuates vector-induced inflammation and the immune response to the vectors or the transgene products, and thus effectively augments and prolongs gene expression; 4) the anatomical structure of the lung enables trans-airway access and local gene delivery - as well as re-transfection. A number of issues need to be considered to develop a strategy of gene delivery in lung transplantation: administration route (intra-airway, trans-vascular, intravenous, intramuscular), timing (donor in-vivo, ex-vivo organ transfection or recipient), vector selection and gene selection. Based on our work and the work of others, over the last decade, we present the state of art of in gene therapy in lung transplantation and exciting future directions in the field.

Administration, Inhalation↗
PubMed2005

TNFalpha-induced long pentraxin PTX3 expression in human lung epithelial cells via JNK.

Long pentraxin 3 (PTX3), an acute-phase protein, is a newly clarified mediator for innate immunity and inflammation. As a soluble pattern recognition receptor, it has a nonredundant role in antifungal infection. Overexpression of PTX3 worsens acute lung injury. The lung epithelium is a critical factor in defense against pulmonary pathogens; it is also involved in acute inflammatory responses related to tissue injury. However, very little is known about how PTX3 is regulated in the lung epithelium. In this study, we found that i.v. injection of LPS induced PTX3 expression in rat lung alveolar epithelium. Using human lung cell lines and primary epithelial cells, we found that PTX3 expression was significantly up-regulated by TNF-alpha in a time- and dose-dependent manner, but not by LPS. Pretreatment with either actinomycin D or cycloheximide abolished TNF-alpha-induced PTX3 expression, indicating the requirement for both transcriptional and translational regulation. The TNF-alpha-induced PTX3 expression was blocked by SP600125, a JNK-specific inhibitor, but not by the inhibitors against NF-kappaB, ERKs, or p38 MAPK. Knockdown of either JNK1 or JNK2 with small interfering RNA also significantly reduced the regulated PTX3 expression. Thus, lung epithelial cells appear to be a major local source for PTX3 production, which could be induced in vivo from these cells by LPS or other inflammatory stimuli, and may be an important mediator for host defense and tissue damage. The importance of the JNK pathway for the regulated PTX3 expression may be a potential target for its regulation in the lung.

Animals↗
PubMed2005

Activation of mitogen-activated protein kinases during human lung transplantation.

BACKGROUND: Ischemia-reperfusion is one of the unavoidable steps in lung transplantation; it is associated with acute inflammatory responses and cell death. The intracellular signal transduction mechanisms of these events are largely unknown. We hypothesize that activation of mitogen-activated protein kinases (MAPKs) is one of the important signaling events during human lung transplantation. METHODS: Lung tissue biopsies were performed on 15 patients undergoing transplantation: after cold ischemic preservation; after warm ischemia (implantation); and after 1- or 2-hour reperfusion. The phosphorylation status of MAPK isoforms (ERK, p38-MAPK and JNK) was examined by Western blotting. RESULTS: Phosphorylation of ERK was dramatically increased during the first 2 hours of reperfusion. Phosphorylation of JNK also significantly increased at lower levels. In contrast, phosphorylation of p38 showed no significant changes. CONCLUSIONS: We speculate that the rapid and sustained activation of ERK and JNK during the early reperfusion period may contribute to acute inflammatory responses and cell death of lung grafts.

Adolescent↗
PubMed2005

CFTR DeltaF508 mutation has minimal effect on the gene expression profile of differentiated human airway epithelia.

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial chloride channel regulated by phosphorylation. Most of the disease-associated morbidity is the consequence of chronic lung infection with progressive tissue destruction. As an approach to investigate the cellular effects of CFTR mutations, we used large-scale microarray hybridization to contrast the gene expression profiles of well-differentiated primary cultures of human CF and non-CF airway epithelia grown under resting culture conditions. We surveyed the expression profiles for 10 non-CF and 10 DeltaF508 homozygote samples. Of the 22,283 genes represented on the Affymetrix U133A GeneChip, we found evidence of significant changes in expression in 24 genes by two-sample t-test (P < 0.00001). A second, three-filter method of comparative analysis found no significant differences between the groups. The levels of CFTR mRNA were comparable in both groups. There were no significant differences in the gene expression patterns between male and female CF specimens. There were 18 genes with significant increases and 6 genes with decreases in CF relative to non-CF samples. Although the function of many of the differentially expressed genes is unknown, one transcript that was elevated in CF, the KCl cotransporter (KCC4), is a candidate for further study. Overall, the results indicate that CFTR dysfunction has little direct impact on airway epithelial gene expression in samples grown under these conditions.

Cell Differentiation↗