Spatial Network Mapping of Pulmonary Multidrug-Resistant Tuberculosis Cavities Using RNA Sequencing.

Rationale: There is poor understanding about protective immunity and the pathogenesis of cavitation in patients with tuberculosis.Objectives: To map pathophysiological pathways at anatomically distinct positions within the human tuberculosis cavity.Methods: Biopsies were obtained from eight predetermined locations within lung cavities of patients with multidrug-resistant tuberculosis undergoing therapeutic surgical resection (n = 14) and healthy lung tissue from control subjects without tuberculosis (n = 10). RNA sequencing, immunohistochemistry, and bacterial load determination were performed at each cavity position. Differentially expressed genes were normalized to control subjects without tuberculosis, and ontologically mapped to identify a spatially compartmentalized pathophysiological map of the cavity. In silico perturbation using a novel distance-dependent dynamical sink model was used to investigate interactions between immune networks and bacterial burden, and to integrate these identified pathways.Measurements and Main Results: The median (range) lung cavity volume on positron emission tomography/computed tomography scans was 50 cm3 (15-389 cm3). RNA sequence reads (31% splice variants) mapped to 19,049 annotated human genes. Multiple proinflammatory pathways were upregulated in the cavity wall, whereas a downregulation "sink" in the central caseum-fluid interface characterized 53% of pathways including neuroendocrine signaling, calcium signaling, triggering receptor expressed on myeloid cells-1, reactive oxygen and nitrogen species production, retinoic acid-mediated apoptosis, and RIG-I-like receptor signaling. The mathematical model demonstrated that neuroendocrine, protein kinase C-θ, and triggering receptor expressed on myeloid cells-1 pathways, and macrophage and neutrophil numbers, had the highest correlation with bacterial burden (r > 0.6), whereas T-helper effector systems did not.Conclusions: These data provide novel insights into host immunity to Mycobacterium tuberculosis-related cavitation. The pathways defined may serve as useful targets for the design of host-directed therapies, and transmission prevention interventions.

Drug-Penetration Gradients Associated with Acquired Drug Resistance in Patients with Tuberculosis.

RATIONALE: Acquired resistance is an important driver of multidrug-resistant tuberculosis (TB), even with good treatment adherence. However, exactly what initiates the resistance and how it arises remain poorly understood. OBJECTIVES: To identify the relationship between drug concentrations and drug susceptibility readouts (minimum inhibitory concentrations [MICs]) in the TB cavity. METHODS: We recruited patients with medically incurable TB who were undergoing therapeutic lung resection while on treatment with a cocktail of second-line anti-TB drugs. On the day of surgery, antibiotic concentrations were measured in the blood and at seven prespecified biopsy sites within each cavity. Mycobacterium tuberculosis was grown from each biopsy site, MICs of each drug identified, and whole-genome sequencing performed. Spearman correlation coefficients between drug concentration and MIC were calculated. MEASUREMENTS AND MAIN RESULTS: Fourteen patients treated for a median of 13 months (range, 5-31 mo) were recruited. MICs and drug resistance-associated single-nucleotide variants differed between the different geospatial locations within each cavity, and with pretreatment and serial sputum isolates, consistent with ongoing acquisition of resistance. However, pretreatment sputum MIC had an accuracy of only 49.48% in predicting cavitary MICs. There were large concentration-distance gradients for each antibiotic. The location-specific concentrations inversely correlated with MICs (P < 0.05) and therefore acquired resistance. Moreover, pharmacokinetic/pharmacodynamic exposures known to amplify drug-resistant subpopulations were encountered in all positions. CONCLUSIONS: These data inform interventional strategies relevant to drug delivery, dosing, and diagnostics to prevent the development of acquired resistance. The role of high intracavitary penetration as a biomarker of antibiotic efficacy, when assessing new regimens, requires clarification.

Distinct genetic association at the PLCE1 locus with oesophageal squamous cell carcinoma in the South African population.

Oesophageal squamous cell carcinoma (OSCC) has a high prevalence in the Black and Mixed Ancestry populations of South Africa. Recently, three genome-wide association studies in Chinese populations identified five new OSCC susceptibility loci, including variants at PLCE1, C20orf54, PDE4D, RUNX1 and UNC5CL, but their contribution to disease risk in other populations is unknown. In this study, we report testing variants from these five loci for association with OSCC in the South African Black (407 cases and 849 controls) and Mixed Ancestry (257 cases and 860 controls) populations. The RUNX1 variant rs2014300, which reduced risk in the Chinese population, was associated with an increased risk of OSCC in the Mixed Ancestry population [odds ratio (OR) = 1.33, 95% confidence interval (CI) = 1.09-1.63, P = 0.0055], and none of the five loci were associated in the Black population. Since PLCE1 variants increased the risk of OSCC in all three Chinese studies, this gene was investigated further by sequencing in 46 Black South Africans. This revealed 48 variants, 10 of which resulted in amino acid substitutions, and much lower linkage disequilibrium across the PLCE1 locus than in the Chinese population. We genotyped five PLCE1 variants in cases and controls, and found association of Arg548Leu (rs17417407) with a reduced risk of OSCC (OR = 0.74, 95% CI = 0.60-0.93, P = 0.008) in the Black population. These findings indicate several differences in the genetic contribution to OSCC between the South African and Chinese populations that may be related to differences in their genetic architecture.

Remodeling leads to distinctly more intimal hyperplasia in coronary than in infrainguinal vein grafts.

BACKGROUND: Flow patterns and shear forces in native coronary arteries are more protective against neointimal hyperplasia than those in femoral arteries. Yet, the caliber mismatch with their target arteries makes coronary artery bypass grafts more likely to encounter intimal hyperplasia than their infrainguinal counterparts due to the resultant slow flow velocity and decreased wall stress. To allow a site-specific, flow-related comparison of remodeling behavior, saphenous vein bypass grafts were simultaneously implanted in femoral and coronary positions. METHODS: Saphenous vein grafts were concomitantly implanted as coronary and femoral bypass grafts using a senescent nonhuman primate model. Duplex ultrasound-based blood flow velocity profiles and vein graft and target artery dimensions were correlated with dimensional and histomorphologic graft remodeling in large, senescent Chacma baboons (n = 8; 28.1 ± 4.9 kg) during a 24-week period. RESULTS: At implantation, the cross-sectional quotient (Q(c)) between target arteries and vein grafts was 0.62 ± 0.10 for femoral grafts vs 0.17 ± 0.06 for coronary grafts, resulting in a dimensional graft-to-artery mismatch 3.6 times higher (P < .0001) in coronary grafts. Together with different velocity profiles, these site-specific dimensional discrepancies resulted in a 57.9% ± 19.4% lower maximum flow velocity (P = .0048), 48.1% ± 23.6% lower maximal cycling wall shear stress (P = .012), and 62.2% ± 21.2% lower mean velocity (P = .007) in coronary grafts. After 24 weeks, the luminal diameter of all coronary grafts had contracted by 63%, from an inner diameter of 4.49 ± 0.60 to 1.68 ± 0.63 mm (P < .0001; subintimal diameter: -41.5%; P = .002), whereas 57% of the femoral interposition grafts had dilated by 31%, from 4.21 ± 0.25 to 5.53 ± 1.30 mm (P = .020). Neointimal tissue was 2.3 times thicker in coronary than in femoral grafts (561 ± 73 vs 240 ± 149 µm; P = .001). Overall, the luminal area of coronary grafts was an average of 4.1 times smaller than that of femoral grafts. CONCLUSIONS: Although coronary and infrainguinal bypass surgery uses saphenous veins as conduits, they undergo significantly different remodeling processes in these two anatomic positions.

Knitted nitinol represents a new generation of constrictive external vein graft meshes.

OBJECTIVE: Constriction of vein grafts with braided external nitinol meshes had previously led to the successful elimination of neointimal tissue formation. We investigated whether pulse compliance, smaller kink-free bending radius, and milder medial atrophy can be achieved by knitting the meshes rather than braiding, without losing the suppressive effect on intimal hyperplasia. METHODS: Pulse compliance, bending stiffness, and bending radius, as well as longitudinal-radial deformation-coupling and radial compression, were compared in braided and knitted nitinol meshes. Identical to previous studies with braided mesh grafts, a senescent nonhuman primate model (Chacma baboons; bilateral femoral interposition grafts/6 months) mimicking the clinical size mismatch between vein grafts and runoff arteries was used to examine the effect of knitted external meshes on vein grafts: nitinol mesh-constricted (group 1); nitinol mesh-constricted and fibrin sealant (FS) spray-coated for mesh attachment (group 2); untreated control veins (group 3), and FS spray-coated control veins (group 4). RESULTS: Compared with braided meshes, knitted meshes had 3.8-times higher pulse compliance (3.43 ± 0.53 vs 0.94 ± 0.12%/100 mm Hg; P = .00002); 30-times lower bending stiffness (0.015 ± 0.002 vs 0.462 ± 0.077 Nmm(2); P = .0006); 9.2-times narrower kink-free bending radius (15.3 ± 0.4 vs 140.8 ± 22.4 mm; P = .0006), and 4.3-times lower radial narrowing caused by axial distension (18.0% ± 1.0% vs 77.0% ± 3.7%; P = .00001). Compared with mesh-supported grafts, neointimal tissue was 8.5-times thicker in group I (195 ± 45 µm) vs group III (23.0 ± 21.0 µm; P < .001) corresponding with a 14.3-times larger neointimal area in group I (4330 ± 957 × 103 µm(2)) vs group III (303 ± 221× 103 µm(2); P < .00004). FS had no significant influence. Medial muscle mass remained at 43.4% in knitted meshes vs the 28.1% previously observed in braided meshes. CONCLUSION: Combining the suppression of intimal hyperplasia with a more physiologic remodeling process of the media, manifold higher kink-resistance, and lower fraying than in braided meshes makes knitted nitinol an attractive concept in external vein graft protection.

Utilization of shape memory in external vein-graft meshes allows extreme diameter constriction for suppressing intimal hyperplasia: a non-human primate study.

OBJECTIVE: Constrictive external Nitinol meshes have been shown to suppress neointimal tissue formation and preserve endothelial integrity in vein grafts. As this mitigating effect increased with the degree of constriction, we investigated whether extreme constriction was possible without leading to detrimental luminal encroachment. METHODS: A senescent non-human primate model (Chacma baboons/bilateral femoral interposition grafts) mimicking the clinical size-mismatch between vein grafts and run-off arteries was used. Control grafts were either untreated (group 1) or spray-coated with fibrin glue (group 2). Nitinol meshes constricting the lumen by 90% (group 4). Anastomotic size mismatch at implantation was expressed as quotient of cross-sectional area of run-off artery to vein graft (Q(C)). RESULTS: At 6 months, all vein grafts without mesh support showed thick eccentric layers of neointimal tissue (group 1: 348 +/- 130 microm [Q(C) median at implant 0.19]; group 2: 318 +/- 142 microm [Q(C) median at implant 0.17]). Fibrin glue-spraying had no effect. In contrast, neointimal tissue was absent in all mesh-supported grafts (P < .007 in all cases) both at 6 weeks/6 months (group 3: 7.5 +/- 8.8 mum and 2.5 +/- 4.4 microm [Q(C) median at implant 1.47]; group 4: 1.3 +/- 0.6 microm and 3.8 +/- 5.6 microm [Q(C) median at implant 3.09]). Except for mild tissue buckling (fold height <356 microm) in one group 3 graft, none of the mesh-constricted grafts showed wall folds. Endothelial coverage was only complete in the mesh-supported groups (100% in group 3 and 4 vs 85 +/- 14%; P < .023 in group 1). Fibrin glue alone (52 +/- 48%) did not preserve endothelialization of control grafts (P < .38). CONCLUSION: Extreme vein graft constriction using external Nitinol meshes is possible without detrimental tissue buckling. Although moderate constriction was found to be sufficient for mitigating diffuse intimal hyperplasia and endothelial detachment, extreme constriction may occasionally be required to eliminate luminal irregularities.

Patient and tumour characteristics as prognostic markers for oesophageal cancer: a retrospective analysis of a cohort of patients at Groote Schuur Hospital.

OBJECTIVES: In addition to the high incidence of squamous carcinoma of the oesophagus among South African men, the neoplasm is also characterized by an exceptionally latent course and poor prognosis. The aim of this study was to review a cohort of patients with carcinoma of the oesophagus presenting to the Groote Schuur Hospital, Cape Town and evaluate patient and tumour characteristics for their role as prognostic markers for survival. METHODS: Information on patients was extracted from a database established and maintained over a 30-year period. Information for the analysis included patient demographics, clinical symptoms at presentation, tumour characteristics and treatment decisions. Statistical analyses were performed using GraphPad Prism 5 applying chi-square and Kaplan-Meier tests. RESULTS: Data were available on 1868 patients. The majority of patients were Black African men and the predominant histology was squamous cell carcinoma. There were significant differences (P < 0.05) in the survival of patients with respect to race (P < 0.001), performance status (P < 0.001), weight loss (P = 0.001) and prior tuberculosis diagnosis (P = 0.007). Tumour characteristics that were significantly associated with survival were histological type, tumour size and site. Gender, prior cancer, smoking status and tumour-related pain did not show significant association with survival in patients with oesophageal cancer. Only 19.8% of the patients were candidates for potentially curative treatment. CONCLUSIONS: This analysis shows that there are prominent patient and tumour characteristics that are significantly associated with survival with respect to oesophageal carcinoma. The inclusion of these factors in the initial assessment of patients may assist with appropriate treatment decisions.

Resurgence of therapeutically destitute tuberculosis: amalgamation of old and newer techniques.

Most of thoracic surgery developed as a result of efforts to treat tuberculosis (TB). The role of surgical therapy has declined but the role of surgery in TB still remains in situations like diagnostic difficulties, persistent sputum positive state despite therapy and complications and sequel like haemoptysis, destroyed or bronchiectatic lungs or empyema with or without broncho-pleural fistula (BPF). Various procedures have a role according to the indication. Some of the procedures have become obsolete but lobectomy, pneumonectomy, thoracoplasty, decortication and open window thoracostomy continue to be relevant. Recent published series have demonstrated mortality ranging from 0% to 3.1%. Surgery for complications and sequel of pulmonary TB still remain an important intervention for alleviation of human misery.

Aspergilloma and the surgeon.

Aspergillus fungus is a ubiquitous saprophyte that is the causative organism for the development of an aspergilloma. The most common species causing an aspergilloma is the Apergillus fumigatus. An aspergilloma is a conglomeration of mucus, inflammatory cells and altered blood elements. Aspergillomas typically form in pre-existing lung pathology, most notably and commonly in old healed tuberculosis cavities. They are classified into simple and complex types that have clinical relevance. Symptoms are very variable and it is not uncommon to incidentally find a lung aspergilloma. In most case series, the most common presenting symptom is haemoptysis which varies from mild to catastrophic bleeds. Given the limited information about the natural history of the disease, there is unfortunately no recognised factor or variable which can predict how an aspergilloma will manifest itself, hence the manner of treatment is a still a topic of debate among treating physicians. The mainstay of treatment is surgical intervention and medical options although disappointing at the current stage, require further investigation in light of the newer available anti-fungal agents. The need for surgical intervention is however not as clear-cut as one would like, since many patients have multiple co-morbidities and other diffuse or focal lung pathology, making the decision process indeterminate in certain instances. In this review, we focus on the different surgical options available for the management of aspergilloma across variable clinical settings, and we propose an approach to its management.

The medical and surgical treatment of drug-resistant tuberculosis.

Multi drug-resistant tuberculosis (MDR-TB) and extensively drug-resistant TB (XDR-TB) are burgeoning global problems with high mortality which threaten to destabilise TB control programs in several parts of the world. Of alarming concern is the emergence, in large numbers, of patients with resistance beyond XDR-TB (totally drug-resistant TB; TDR-TB or extremely drug resistant TB; XXDR-TB). Given the burgeoning global phenomenon of MDR-TB, XDR-TB and TDR-TB, and increasing international migration and travel, healthcare workers, researchers, and policy makers in TB endemic and non-endemic countries should familiarise themselves with issues relevant to the management of these patients. Given the lack of novel TB drugs and limited access to existing drugs such as linezolid and bedaquiline in TB endemic countries, significant numbers of therapeutic failures are emerging from the ranks of those with XDR-TB. Given the lack of appropriate facilities in resource-limited settings, such patients are being discharged back into the community where there is likely ongoing disease spread. In the absence of effective drug regimens, in appropriate patients, surgery is a critical part of management. Here we review the diagnosis, medical and surgical management of MDR-TB and XDR-TB.

Approach to a solid solitary pulmonary nodule in two different settings-"Common is common, rare is rare".

A new solid solitary pulmonary nodule (SPN) is a common feature in the daily practice of physicians, pulmonologists and thoracic surgeons. The etiology and consequently the diagnostic approach is very different in various parts of the world. Identification of malignant nodules is the universal goal to proceed to a potential curable therapy. In countries with a low incidence of inflammatory disease and a high incidence of lung cancer the diagnostic work up includes a positron emission tomography (PET) scan or PET-computer tomography (CT) as a main pillar. In countries with a high incidence of inflammatory and infectious disease and a low incidence in lung cancer this diagnostic work up needs to be adapted. In these settings a PET scan has a limited role and tissue diagnosis, whether with a trans-thoracic, trans-bronchial biopsy or a video-assisted wedge resection is the most targeted approach to determine or exclude malignancy. The evaluation of a solid SPN in the two different situations is outlined in our algorithm. Recommendations stress the value of clinical judgement in different settings, determination of probabilities of malignancy, cost-effective use of diagnostic tools and evaluation of various management alternatives according to the risk profile and the patients preferences.

Protective constriction of coronary vein grafts with knitted nitinol.

OBJECTIVES: Different flow patterns and shear forces were shown to cause significantly more luminal narrowing and neointimal tissue proliferation in coronary than in infrainguinal vein grafts. As constrictive external mesh support of vein grafts led to the complete suppression of intimal hyperplasia (IH) in infrainguinal grafts, we investigated whether mesh constriction is equally effective in the coronary position. METHODS: Eighteen senescent Chacma baboons (28.8 ± 3.6 kg) received aorto-coronary bypass grafts to the left anterior descending artery (LAD). Three groups of saphenous vein grafts were compared: untreated controls (CO); fibrin sealant-sprayed controls (CO + FS) and nitinol mesh-constricted grafts (ME + FS). Meshes consisted of pulse-compliant, knitted nitinol (eight needles; 50 µm wire thickness; 3.4 mm resting inner diameter, ID) spray attached to the vein grafts with FS. After 180 days of implantation, luminal dimensions and IH were analysed using post-explant angiography and macroscopic and histological image analysis. RESULTS: At implantation, the calibre mismatch between control grafts and the LAD expressed as cross-sectional quotient (Qc) was pronounced [Qc = 0.21 ± 0.07 (CO) and 0.18 ± 0.05 (CO + FS)]. Mesh constriction resulted in a 29 ± 7% reduction of the outer diameter of the vein grafts from 5.23 ± 0.51 to 3.68 ± 0 mm, significantly reducing the calibre discrepancy to a Qc of 0.41 ± 0.17 (P < 0.02). After 6 months of implantation, explant angiography showed distinct luminal irregularities in control grafts (ID difference between widest and narrowest segment 74 ± 45%), while diameter variations were mild in mesh-constricted grafts. In all control grafts, thick neointimal tissue was present [600 ± 63 µm (CO); 627 ± 204 µm (CO + FS)] as opposed to thin, eccentric layers of 249 ± 83 µm in mesh-constricted grafts (ME + FS; P < 0.002). The total wall thickness had increased by 363 ± 39% (P < 0.00001) in CO and 312 ± 61% (P < 0.00001) in CO + FS vs 82 ± 61% in ME + FS (P < 0.007). CONCLUSIONS: In a senescent non-human primate model for coronary artery bypass grafts, constrictive, external mesh support of saphenous veins with knitted nitinol prevented focal, irregular graft narrowing and suppressed neointimal tissue proliferation by a factor of 2.5. The lower degree of suppression of IH compared with previous infrainguinal grafts coincided with a lesser reduction of calibre mismatch in the coronary grafts.