Controversies in chronic kidney disease staging

In 2002, a new chronic kidney disease staging system was developed by the US National Kidney Foundation. The classification system represented a new conceptual framework for the diagnosis of chronic kidney disease (moving to a schema based on disease severity defined by the glomerular filtration rate). While the introduction of the staging system stimulated significant clinical and research interest in kidney disease, there has been vigorous debate on its merits. This mini-review aims to summarise the recent controversies that have been raised since the introduction of the new classification.     

Controversies over stem cell research

Much interest and effort has focused on the therapeutic potential of stem cell technology to treat presently intractable diseases. However, this scientific promise has been accompanied by important issues, including ethical hurdles, political policies and dilemmas concerning cell-source selection (embryonic versus adult stem cells). Although the contribution of stem cells to medical research seems enormous, many countries now face complex ethical and regulatory questions, which could represent a significant limitation to medical progress and could take years to overcome.     

Paleodemography: Critiques and Controversies

Recent criticism of paleodemographic methods (Bocquet-Appel and Masset 1982) has centered on biases introduced by the nature of reference samples and the population-specificity of techniques for estimating age in skeletal remains. This paper examines five key arguments concerning this bias and alleged imprecision from the perspective of life table analysis. The results of our simulation and statistical analyses indicate that the criticism leveled by Bocquet-Appel and Masset is extreme. Imprecision in age indicators applied to older adults remains a problem, however, as does interobserver error.     

Controversies in patient selection for liver transplantation.

A variety of specific conditions often stimulate controversy regarding candidacy for liver transplantation. We review the published experience with liver transplantation for alcoholic liver disease, fulminant and chronic hepatitis B, and hepatocellular carcinoma and transplantation in older subjects. Liver transplantation for alcoholic liver disease and in subjects older than 60 years is becoming less controversial because recent data demonstrate that these patients have excellent survival and good quality of life after transplantation. Only 10% to 15% of persons with alcoholism return to drinking after transplantation, and most do so only transiently. Liver transplantation for patients with hepatitis B virus infection or primary liver cancer is more problematic because recurrent disease is common in both conditions. After transplantation for chronic hepatitis B, 80% to 90% of patients have reinfection of the allograft and long-term survival is 45% to 50%. Patients receiving transplants for hepatocellular carcinoma have only 20% to 30% long-term survival, but these survivors are cured of malignancy. Data are presented to support continued liver transplantation for chronic hepatitis B and hepatocellular carcinoma; however, patients must be selected based on factors that predict a favorable outcome, and experimental therapies should be employed to explore ways to improve the existing survival rates.     

Mapping Intravascular Ultrasound Controversies in Interventional Cardiology Practice

Intravascular ultrasound is a catheter-based imaging modality that was developed to investigate the condition of coronary arteries and assess the vulnerability of coronary atherosclerotic plaques in particular. Since its introduction in the clinic 20 years ago, use of intravascular ultrasound innovation has been relatively limited. Intravascular ultrasound remains a niche technology; its clinical practice did not vastly expand, except in Japan, where intravascular ultrasound is an appraised tool for guiding percutaneous coronary interventions. In this qualitative research study, we follow scholarship on the sociology of innovation in exploring both the current adoption practices and perspectives on the future of intravascular ultrasound. We conducted a survey of biomedical experts with experience in the technology, the practice, and the commercialization of intravascular ultrasound. The collected information enabled us to map intravascular ultrasound controversies as well as to outline the dynamics of the international network of experts that generates intravascular ultrasound innovations and uses intravascular ultrasound technologies. While the technology is praised for its capacity to measure coronary atherosclerotic plaque morphology and is steadily used in clinical research, the lack of demonstrated benefits of intravascular ultrasound guided coronary interventions emerges as the strongest factor that prevents its expansion. Furthermore, most of the controversies identified were external to intravascular ultrasound technology itself, meaning that decision making at the industrial, financial and regulatory levels are likely to determine the future of intravascular ultrasound. In light of opinions from the responding experts'', a wider adoption of intravascular ultrasound as a stand-alone imaging modality seems rather uncertain, but the appeal for this technology may be renewed by improving image quality and through combination with complementary imaging modalities.     

COPD diagnosis related to different guidelines and spirometry techniques

Background

Several studies have indicated that one of the most potent mediators involved in pulmonary vascular remodeling is vascular endothelial growth factor (VEGF). This study was designed to determine whether airway VEGF level reflects pulmonary vascular remodeling in patients with bronchitis-type of COPD.

Methods

VEGF levels in induced sputum were examined in 23 control subjects (12 non-smokers and 11 ex-smokers) and 29 patients with bronchitis-type of COPD. All bronchitis-type patients performed exercise testing with right heart catheterization.

Results

The mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) after exercise were markedly increased in all bronchitis-type patients. However, both parameters after exercise with breathing of oxygen was significantly lower than in those with breathing of room air. To attenuate the effect of hypoxia-induced pulmonary vasoconstriction during exercise, we used the change in mPAP or PVR during exercise with breathing of oxygen as a parameter of pulmonary vascular remodeling. Change in mPAP was significantly correlated with VEGF level in induced sputum from patients with chronic bronchitis (r = 0.73, p = 0.0001). Moreover, change in PVR was also correlated with VEGF level in those patients (r = 0.57, p = 0.003).

Conclusion

A close correlation between magnitude of pulmonary hypertension with exercise and VEGF level in bronchitis-type patients could be observed. Therefore, these findings suggest the possibility that VEGF level in induced sputum is a non-invasive marker of pulmonary vascular remodeling in patients with bronchitis-type of COPD.     

Exercise-induced bronchoconstriction alters airway nitric oxide exchange in a pattern distinct from spirometry

Exhaled nitric oxide (NO) is altered in asthmatic subjects with exercise-induced bronchoconstriction (EIB). However, the physiological interpretation of exhaled NO is limited because of its dependence on exhalation flow and the inability to distinguish completely proximal (large airway) from peripheral (small airway and alveolar) contributions. We estimated flow-independent NO exchange parameters that partition exhaled NO into proximal and peripheral contributions at baseline, postexercise challenge, and postbronchodilator administration in steroid-naive mild-intermittent asthmatic subjects with EIB (24-43 yr old, n = 9) and healthy controls (20-31 yr old, n = 9). The mean +/- SD maximum airway wall flux and airway diffusing capacity were elevated and forced expiratory flow, midexpiratory phase (FEF(25-75)), forced expiratory volume in 1 s (FEV(1)), and FEV(1)/forced vital capacity (FVC) were reduced at baseline in subjects with EIB compared with healthy controls, whereas the steady-state alveolar concentration of NO and FVC were not different. Compared with the response of healthy controls, exercise challenge significantly reduced FEV(1) (-23 +/- 15%), FEF(25-75) (-37 +/- 18%), FVC (-12 +/- 12%), FEV(1)/FVC (-13 +/- 8%), and maximum airway wall flux (-35 +/- 11%) relative to baseline in subjects with EIB, whereas bronchodilator administration only increased FEV(1) (+20 +/- 21%), FEF(25-75) (+56 +/- 41%), and FEV(1)/FVC (+13 +/- 9%). We conclude that mild-intermittent steroid-naive asthmatic subjects with EIB have altered airway NO exchange dynamics at baseline and after exercise challenge but that these changes occur by distinct mechanisms and are not correlated with alterations in spirometry.