Mathematical versus biological reasons for FEV1/FVC dependence on age - a reply to Philip Quanjer (Tomasz Golczewski, 15 August 2012)
Philip Quanjer is right that the ratio FEV1/FVC - like other lung function variables - is nonlinearly dependent on age. It has to be noted that the same 'nonlinearity' can be described mathematically with different formulas. Recently, the exponential formula with the quadratic form in the exponent is 'trendy' but the piecewise linear forms, as those proposed by Quanjer et al in the past [1] and recently by Lubinski and Golczewski [2], is sufficiently nonlinear to describe age-dependence with the same precision as this trendy formula or even better - see Fig.2 in the commented article (particularly if the change point is determined with regression methods together with the other coefficients separately for each lung function variable like in [2]). For this reason, Quanjer's piecewise linear...
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Age dependence of the FEV1/FVC ratio (Philip Quanjer, 01 August 2012)
Gólczewski et al. [1] argue that the FEV1/FVC ratio is age dependent because the FEV1 and FVC are mathematically linked as follows: FEV1 = A¿FVC + C, `without respect to the other factors, including age and height¿. As FVC is age dependent, the authors expect the FEV1/FVC ratio to be also age dependent. Although the FEV1 and FVC are undeniably closely related in healthy subjects, their reasoning is a simplification of the biological determinants of the relationship between FEV1, FVC and the FEV1/FVC ratio. The FVC is determined by a host of factors, including body dimensions, mechanical properties of the thorax, and muscular force, and is therefore age and height dependent. The FEV1 is a portion of the vital capacity that can be inhaled in one second. Whereas it is undoubtedly related to...
read full comment
Adding a sentence to the bottom of the table 1. (Lunyin Yu, 15 December 2011)
Adding the following to the bottom of the table 1. BMC = transplantation of bone marrow cells without shRNA, BMC+S-R = transplantation of bone marrow cells with scrambled shRNA, BMC+ CXCR4 = transplantation of bone marrow cells with CXCR4 shRNA.
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I believe the article would be improved if the authors would substitute Group 1 and Group 2 for: "... ([less than or equal to]50 years old and [greater than or equal to]52 years old..." after initially stating the criteria for each group.
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The differential role of mitochondria in asthmatic lung (Ulaganathan Mabalirajan, 07 September 2010)
This study revealed novel and interesting findings, such as glycolysis and calcium binding in asthmatic early airway response (EAR) in murine OVA model. In addition, they found increased biological activity of mitochondria in asthmatic mice lung during EAR. However, we think that interpretation and discussion related to the mitochondria needs some caution, update and a holistic view. Asthma is a heterogeneous disease and various immune cells and structural cells participate in its pathophysiology. Recent literature has highlighted the importance of mitochondria in asthma pathogenesis. A common finding in asthma is epithelial injury and apoptosis associated with high levels of oxo-nitrosative stress. Mitochondrial dysfunction contributes importantly to this process, leading to large...
read full comment
Comment on: Xu et al. Respiratory Research, 11:107
Circulating endothelial precursors and the hypoxia machinery. Reply to comments (Michele Ciulla, 04 March 2008)
Respiratory ResearchReply to comments December 24, 2007Dear Dr Prakash,Thank you for you interest in our paper that we believe that is the first linking in healthy subjects a simulated altitude [1] with the circulating endothelial precursors and the hypoxia machinery.Your comments give us the opportunity to clarify some aspects.1. In our study we measured the SpotOxygen Saturation of haemoglobin(SpO2)by using a pulseoximeter. Pulseoximetry is the most convenient non-invasive method of monitoring arterial saturation continuously. Although there are many advantages of using pulse oximetry as a tool for monitoring oxygen saturation in arterial blood, there are also potential pitfalls.The pulsatile component of the signal represents the arterial absorption and forms only a small proportion of...
read full comment
Comment on: Ciulla et al. Respiratory Research, 8:58
Re: Effects of normobaric hypoxia on cardiorespiratory parameters and endothelial progenitor cells in peripheral blood in healthy subjects (E Sankaranarayanan Prakash, 14 November 2007)
Ciulla et al are complemented for their investigation of an important research question.From data in Table 1, it is seen that oxygen saturation of hemoglobin is as high as 86.8% (mean value) when alveolar PO2 is as low as 30 mm Hg. Typically, the oxygen saturation of Hb A is expected to be as low as 50% when the arterial PO2 is 30 mm Hg [1]. Were the PAO2 values directly estimated by sampling end tidal alveolar gas? Or were they calculated from the alveolar gas equation? Anyway PaCO2 has not been estimated. In Table 1 (on page 17 of the PDF version), it is mentioned that the concentration of endothelial precursor cells has increased from 0.38 +/- 0.56; [mean (SD)] to 0.65 +/-0.72 cells per microliter. The P value for this difference is noted as 0.016. From calculating a P value with just...
read full comment
Comment on: Ciulla et al. Respiratory Research, 8:58
Re: Pre-natal and post-natal exposure to respiratory infection and atopic diseases development: a historical cohort study. (Roos Maria Desirée Bernsen, 06 July 2006)
We read the interesting study by Zutavern et al (1), approaching the problem of assessing the relationship between (exposure to) infections and allergic diseases in an original way by using population level data as a proxy for individual exposure. Exposure between the start of pregnancy and the first birthday was defined as a high incidence of acute respiratory infections in that period in the region (as reported by physicians to the surveillance system in the former German Democratic Republic). The study population included children (aged 5-14 years) born between 1977 and 1990 in three different regions in the former German Democratic Republic and was assessed between 1992 and 1999. We think, however, that the authors have overlooked an important confounder when adjusting the relationship...
read full comment
adjuvanted vaccines for bird flu counterindicated? (Mary Quijano, 26 November 2005)
Recent research data suggests that the lethality of the H5N1 strain of avian influenza among young healthy adults may be due to its stimulation of an excessive immune response in the epithelial cells of the respiratory system. If this proves to be true, then might it not be counterindicated to provide a lower dose of flu vaccine with adjuvants to stimulate the immune system, as WHO has been proposing to the laboratories producing the vaccines as a solution to inadeqate supplies? The research paper suggests immune suppressors as a possible life saving treatment to those infected with the virus, therefore it would seem stimulating a stronger immune response with adjuvants might be a wrong approach.
read full comment
Comment on: Chan et al. Respiratory Research, 6:135
Correction to Initials on Authors List (W. Alan Mutch, 25 November 2004)
Could you please correct the initials of one of the authors on the web site and on the abstract to agree with the correct initials on the paper.It should read E. K-Y. Walker.Thank you for attention to this request.
read full comment
Comment on: Funk et al. Respiratory Research, 5:22
Competing Interest Statement (W. Alan Mutch, 24 November 2004)
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Latest comments
Mathematical versus biological reasons for FEV1/FVC dependence on age - a reply to Philip Quanjer (Tomasz Golczewski, 15 August 2012)
Philip Quanjer is right that the ratio FEV1/FVC - like other lung function variables - is nonlinearly dependent on age. It has to be noted that the same 'nonlinearity' can be described mathematically with different formulas. Recently, the exponential formula with the quadratic form in the exponent is 'trendy' but the piecewise linear forms, as those proposed by Quanjer et al in the past [1] and recently by Lubinski and Golczewski [2], is sufficiently nonlinear to describe age-dependence with the same precision as this trendy formula or even better - see Fig.2 in the commented article (particularly if the change point is determined with regression methods together with the other coefficients separately for each lung function variable like in [2]). For this reason, Quanjer's piecewise linear... read full comment
Comment on: Gólczewski et al. Respiratory Research, 13:57
Age dependence of the FEV1/FVC ratio (Philip Quanjer, 01 August 2012)
Gólczewski et al. [1] argue that the FEV1/FVC ratio is age dependent because the FEV1 and FVC are mathematically linked as follows: FEV1 = A¿FVC + C, `without respect to the other factors, including age and height¿. As FVC is age dependent, the authors expect the FEV1/FVC ratio to be also age dependent. Although the FEV1 and FVC are undeniably closely related in healthy subjects, their reasoning is a simplification of the biological determinants of the relationship between FEV1, FVC and the FEV1/FVC ratio. The FVC is determined by a host of factors, including body dimensions, mechanical properties of the thorax, and muscular force, and is therefore age and height dependent. The FEV1 is a portion of the vital capacity that can be inhaled in one second. Whereas it is undoubtedly related to... read full comment
Comment on: Gólczewski et al. Respiratory Research, 13:57
Adding a sentence to the bottom of the table 1. (Lunyin Yu, 15 December 2011)
Adding the following to the bottom of the table 1. BMC = transplantation of bone marrow cells without shRNA, BMC+S-R = transplantation of bone marrow cells with scrambled shRNA, BMC+ CXCR4 = transplantation of bone marrow cells with CXCR4 shRNA. read full comment
Comment on: Yu et al. Respiratory Research, 12:21
efficient wording (JULIA PETEET, 12 October 2011)
I believe the article would be improved if the authors would substitute Group 1 and Group 2 for: "... ([less than or equal to]50 years old and [greater than or equal to]52 years old..." after initially stating the criteria for each group. read full comment
Comment on: Carroll et al. Respiratory Research, 11:184
The differential role of mitochondria in asthmatic lung (Ulaganathan Mabalirajan, 07 September 2010)
This study revealed novel and interesting findings, such as glycolysis and calcium binding in asthmatic early airway response (EAR) in murine OVA model. In addition, they found increased biological activity of mitochondria in asthmatic mice lung during EAR. However, we think that interpretation and discussion related to the mitochondria needs some caution, update and a holistic view.
Asthma is a heterogeneous disease and various immune cells and structural cells participate in its pathophysiology. Recent literature has highlighted the importance of mitochondria in asthma pathogenesis. A common finding in asthma is epithelial injury and apoptosis associated with high levels of oxo-nitrosative stress. Mitochondrial dysfunction contributes importantly to this process, leading to large... read full comment
Comment on: Xu et al. Respiratory Research, 11:107
Circulating endothelial precursors and the hypoxia machinery. Reply to comments (Michele Ciulla, 04 March 2008)
Respiratory ResearchReply to comments December 24, 2007Dear Dr Prakash,Thank you for you interest in our paper that we believe that is the first linking in healthy subjects a simulated altitude [1] with the circulating endothelial precursors and the hypoxia machinery.Your comments give us the opportunity to clarify some aspects.1. In our study we measured the SpotOxygen Saturation of haemoglobin(SpO2)by using a pulseoximeter. Pulseoximetry is the most convenient non-invasive method of monitoring arterial saturation continuously. Although there are many advantages of using pulse oximetry as a tool for monitoring oxygen saturation in arterial blood, there are also potential pitfalls.The pulsatile component of the signal represents the arterial absorption and forms only a small proportion of... read full comment
Comment on: Ciulla et al. Respiratory Research, 8:58
Re: Effects of normobaric hypoxia on cardiorespiratory parameters and endothelial progenitor cells in peripheral blood in healthy subjects (E Sankaranarayanan Prakash, 14 November 2007)
Ciulla et al are complemented for their investigation of an important research question.From data in Table 1, it is seen that oxygen saturation of hemoglobin is as high as 86.8% (mean value) when alveolar PO2 is as low as 30 mm Hg. Typically, the oxygen saturation of Hb A is expected to be as low as 50% when the arterial PO2 is 30 mm Hg [1]. Were the PAO2 values directly estimated by sampling end tidal alveolar gas? Or were they calculated from the alveolar gas equation? Anyway PaCO2 has not been estimated. In Table 1 (on page 17 of the PDF version), it is mentioned that the concentration of endothelial precursor cells has increased from 0.38 +/- 0.56; [mean (SD)] to 0.65 +/-0.72 cells per microliter. The P value for this difference is noted as 0.016. From calculating a P value with just... read full comment
Comment on: Ciulla et al. Respiratory Research, 8:58
Re: Pre-natal and post-natal exposure to respiratory infection and atopic diseases development: a historical cohort study. (Roos Maria Desirée Bernsen, 06 July 2006)
We read the interesting study by Zutavern et al (1), approaching the problem of assessing the relationship between (exposure to) infections and allergic diseases in an original way by using population level data as a proxy for individual exposure. Exposure between the start of pregnancy and the first birthday was defined as a high incidence of acute respiratory infections in that period in the region (as reported by physicians to the surveillance system in the former German Democratic Republic). The study population included children (aged 5-14 years) born between 1977 and 1990 in three different regions in the former German Democratic Republic and was assessed between 1992 and 1999. We think, however, that the authors have overlooked an important confounder when adjusting the relationship... read full comment
Comment on: Zutavern et al. Respiratory Research, 7:81
adjuvanted vaccines for bird flu counterindicated? (Mary Quijano, 26 November 2005)
Recent research data suggests that the lethality of the H5N1 strain of avian influenza among young healthy adults may be due to its stimulation of an excessive immune response in the epithelial cells of the respiratory system. If this proves to be true, then might it not be counterindicated to provide a lower dose of flu vaccine with adjuvants to stimulate the immune system, as WHO has been proposing to the laboratories producing the vaccines as a solution to inadeqate supplies? The research paper suggests immune suppressors as a possible life saving treatment to those infected with the virus, therefore it would seem stimulating a stronger immune response with adjuvants might be a wrong approach. read full comment
Comment on: Chan et al. Respiratory Research, 6:135
Correction to Initials on Authors List (W. Alan Mutch, 25 November 2004)
Could you please correct the initials of one of the authors on the web site and on the abstract to agree with the correct initials on the paper.It should read E. K-Y. Walker.Thank you for attention to this request. read full comment
Comment on: Funk et al. Respiratory Research, 5:22
Competing Interest Statement (W. Alan Mutch, 24 November 2004)
See below. read full comment
Comment on: Funk et al. Respiratory Research, 5:22