- Email: [email protected]
Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1–18)
Analytica Chimica Acta xxx (2017) 1e4
Contents lists available at ScienceDirect
Analytica Chimica Acta journal homepage: www.elsevier.com/locate/aca
Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18) Dominic J. Hare a, b, * a b
Elemental Bio-imaging Facility, University of Technology Sydney, Broadway, New South Wales 2007, Australia The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
a r t i c l e i n f o Article history: Received 5 February 2017 Received in revised form 20 March 2017 Accepted 21 March 2017 Available online xxx
Contents Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00
I am writing to express concerns regarding the review article 'Bioimaging mass spectrometry of trace elements e recent advance and applications of LA-ICP-MS: A review' by J Sabine Becker and colleagues from 2014 [1]. In my opinion, this review has made some serious and unsubstantiated criticisms of work from our laboratory. Although I was aware of these issues at the time of publication, the increasing number of citations it has received over the past few years has led me to contact Analytica Chimica Acta to correct the misleading information that has now become regularly referenced as a representation of the current state of the art of laser ablationinductively coupled plasma-mass spectrometry (LA-ICP-MS) in the biological sciences. On page 14, the authors refer to our study of changes in brain cobalt levels induced by intermittent hypoxia [2]. The authors write: “Recently the same research group [2] compared brain sections of 5 common mice after 8 weeks of intermittent hypoxyia [sic] versus 6 controls. The elevation of 59Co from 62 to 5600 ng g1 localized to white matter, seems biologically highly non-plausible and may rather originate from a different batch (storage in metallic vessels) of
* Elemental Bio-imaging Facility, University of Technology Sydney, Broadway, New South Wales 2007, Australia. E-mail address: [email protected].
formalin solution used for perfusion and fixation”. I acknowledge that the reported concentrations of cobalt in the long-term intermittent hypoxic (LTIH) mouse brain are particularly high, and we ourselves were surprised at the 93-fold increase compared to animals exposed to sham intermittent hypoxic conditions, and expressed this sentiment in the report. This finding spurred on the additional experiments to understand why such an increase occurred, and these were described at length in the paper. These experiments were entirely ignored by the authors of this review, and the results were dismissed as being “biologically highly non-plausible”. We used our well-established and analyticallyvalidated matrix-matched external calibration method [3,4] and have confidence in the analytical figures reported. Although high, cobalt concentrations within the same order of magnitude have been detected in biological tissue (bovine liver) using a wellvalidated atomic absorption spectroscopy method [5]. As cobalt is an essential cofactor in vitamin B12, which is critical for processes such as one carbon metabolism in the central nervous system [6], we examined several biomarkers of impaired neurological function and vitamin B12 activity in both treatment groups. Increased cobalt concentration coincided with elevated markers of oxidative stress, damage to myelin sheaths and evidence of axonal degeneration, as well as decreased serum methylmalonic acid levels, which are indicative of increased vitamin B12 activity. This substantial evidence supports our hypothesis that long-term intermittent hypoxia increases brain vitamin B12, and that
http://dx.doi.org/10.1016/j.aca.2017.03.042 0003-2670/© 2017 Elsevier B.V. All rights reserved.
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
2
D.J. Hare / Analytica Chimica Acta xxx (2017) 1e4
elevated cobalt levels are not ‘biologically highly non-plausible’. The review authors attempted to explain the increase as potentially having “originate[d] from a different batch (storage in metallic vessels)”. This comment is entirely speculative and essentially suggests that we would be so careless as to store tissue from an experiment specifically designed to assess metal levels in metal containers, and that we had intentionally segregated the experimental groups so that only the LTIH tissue was housed in such vessels. Even if leaching of cobalt from metal containers (which would typically be stainless steel containing only trace levels of cobalt) was a plausible explanation for elevated cobalt levels, would we not also see an increase in iron levels in the treatment group? Indeed, we did measure iron, which showed no statistical difference (t ¼ 1.92; df ¼ 9; P ¼ 0.087) between groups.
Another unsubstantiated speculative reason for cobalt increase presented by the review was infiltration from the “formalin solution used for perfusion and fixation”. We have experimentally shown that transition metals universally leach out of, not in to, brain tissue during fixation and cryopreservation [7]. Unpublished data from our group has identified that cobalt is prone to this effect, retaining only 18.4 ± 1.6% of the brain's original cobalt content after prolonged fixation and cryoprotection. I also stress that in our study, both sham and LTIH brains underwent identical sample preparation steps. The claim that the increase could be “isobaric interferences at m/ z ¼ 59 may it be 40Ar18O1Hþ or 28Si31Pþ resulting from ablating glass under the sections of the treated group” is, again, baseless and incorrect. As is clear from the paper in question, experimental
Fig. 1. Sample order (a) and quantitative iron (b), copper (c) and zinc (d) maps in the mouse brain. Reprinted with permission from Hare et al. [9]. Copyright 2012 American Chemical Society.
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
D.J. Hare / Analytica Chimica Acta xxx (2017) 1e4
parameters for all imaging experiments were identical, regardless of treatment group. Additionally, the energy fluence of 0.8 J cm2 is well below the threshold required to ablate silicate glass (minimum threshold ¼ 2.4 J cm2 [8]). Considering the authors' reputation in laser ablation, it is surprising that they included this clearly incorrect statement. Taken together, all these critical points were conveniently ignored by Becker and colleagues, as they clearly did not fit the narrative they wished to present and entirely excluded the biological context of the study, which is essential if this unique analytical technique is to be fully accepted in medical research. My second major concern regarding this review appears on page 15, when the authors critique our 2012 Analytical Chemistry paper [9]: “[a]ll sections from one slide where [sic] ablated together in a single run, which further comprised three measurements of a standard series, with a non-specified number of line-scans at non specified time points. Therefore, in the series of resulting concentration maps discontinuations between the three slides are clearly discernable [sic]”. Again, the authors have taken it upon themselves to interpret our published data while conveniently ignoring the context to fit their own narrative. As is explained in the paper in question, standards were run three times over a consecutive 158-h experiment, and Becker and colleagues note that three slides of samples were analysed. It is not a major leap of logic for readers to recognise that standards were run for each ablated slide. Regarding discontinuations being clearly discernible, we assume the reviewers are referring to Fig. 2 in the original manuscript (reproduced here as Fig. 1), and it would seem that they have simply misinterpreted the order of samples, which are marked in panel A. We clearly state in our paper that standards were used for external calibration and was measured three times “to monitor and correct for signal drift” [9]. The authors of this review state that “[a]t the edges of the sections displayed concentrations are artificially high due pixel wise division by the unsmoothed 13C image exhibiting low pixel values at the edges due to partial volume effects.” Again, the interpretation of our data is
3
incorrect; if this effect was indeed due to an “unsmoothed 13C image”, would we not see the same effect for all three measured analytes? Simple inspection of Fig. 1 shows this is not the case. Finally, Becker and colleagues write “[a]lthough the 3D reconstruction was not convincing, this work enables a comprehensive understanding of the architecture of Fe and Cu throughout the mouse brain e Zn had obviously been partially washed out e and deserves online accessibility.” I appreciate and agree with the authors regarding the need for online accessible resources (the full anatomical metal atlas is available as electronic supplementary information for the paper in question), and my group has gone on to drastically improve our three-dimensional reconstruction methods [10]. I am, however, again troubled to see a completely unsubstantiated comment made with no supporting evidence, this time referring to zinc being “partially washed out”. We acknowledge, and have (as mentioned previously) experimentally demonstrated [7] that a degree of metals are lost during sample preparation, but a simple consultation of the literature would make the authors aware that some of the highest zinc concentrations appear in the cerebral neocortex, and histochemical stains used for identifying ionic zinc (Fig. 2a) show the same pattern of zinc distribution as we presented (Fig. 2b). In fact, their very own previous work (Fig. 2c and d; slightly posterior to Fig. 2b) [11,12] shows the same neuroanatomical distribution. In summary, it concerns me that this work is continued to be used as a reference for biological applications of LA-ICP-MS, considering the clear misinterpretation of work from our laboratory. At the very least I believe the authors should issue an erratum and reassess or even retract the sections in question so as to ensure that the rigorous work from myself and my peers, which was subject to the level of peer review expected of original research papers, does not continue to be misrepresented in this way. In the meantime, I direct researchers using LA-ICP-MS imaging in the biosciences to the more balanced review by Pozebon et al. [13] (as well as their very recent follow-up review [14]) when describing
Fig. 2. (a) Timm's histochemical stain for zinc (II) ions in the rat brain [15]. Reprinted with permission from Cell Press (Copyright 2003). (b) Quantitative zinc distribution at a similar anatomical level measured using LA-ICP-MS from our laboratory. Reprinted with permission from the American Chemical Society (Copyright 2012) [9]. (c) and (d) Similar quantitative images of zinc in the mouse brain produced in the laboratory of Becker and colleagues. (c) is reprinted (adapted) from Matusch et al. [12] with permission from the American Chemical Society (Copyright 2012). (d) is reprinted (adapted) from Matusch et al. [11] with permission from Springer (Copyright 2010).
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
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D.J. Hare / Analytica Chimica Acta xxx (2017) 1e4
the current capabilities of this technology. Acknowledgements Dr Hare is supported by a National Health and Medical Research Council Career Development Fellowship (APP1122981), with additional support from Agilent Technologies. He is also supported by an Australian Research Council Linkage Project (LP120200081) with Agilent Technologies and ESI. The Florey Institute of Neuroscience and Mental Health acknowledge the Operational Infrastructure Support from the Victorian State Government. References [1] J.S. Becker, A. Matusch, B. Wu, Bioimaging mass spectrometry of trace elements e recent advance and applications of LA-ICP-MS: a review, Anal. Chim. Acta 835 (2014) 1e18. [2] S.C. Veasey, J. Lear, Y. Zhu, J.B. Grinspan, D.J. Hare, S. Wang, D. Bunch, P.A. Doble, S.R. Robinson, Long-term intermittent hypoxia elevates cobalt levels in the brain, Sleep 36 (2013) 1471e1481. [3] D.J. Hare, J. Lear, D. Bishop, A. Beavis, P.A. Doble, Protocol for production of matrix-matched brain tissue standards for imaging by laser ablationinductively coupled plasma-mass spectrometry, Anal. Methods 5 (2013) 1915e1921. [4] D.J. Hare, B. Reedy, R. Grimm, S. Wilkins, I. Volitakis, J.L. George, R.A. Cherny, A.I. Bush, D.I. Finkelstein, P. Doble, Quantitative elemental bio-imaging of Mn, Fe, Cu and Zn in 6-hydroxydopamine induced Parkinsonism mouse models, Metallomics 1 (2009) 53e58. brega, Acid [5] G.L. Donati, C.C. Nascentes, A.R.A. Nogueira, M.A.Z. Arruda, J.A. No extraction and cloud point preconcentration as sample preparation strategies for cobalt determination in biological materials by thermospray flame furnace atomic absorption spectrometry, Microchem. J. 82 (2006) 189e195. [6] E. Reynolds, Vitamin B12, folic acid, and the nervous system, Lancet Neurol. 5 (2006) 949e960.
[7] D.J. Hare, J.L. George, L. Bray, I. Volitakis, A. Vais, T.M. Ryan, R.A. Cherny, A.I. Bush, C.L. Masters, P.A. Adlard, P.A. Doble, D.I. Finkelstein, The effect of paraformaldehyde fixation and sucrose cryoprotection on metal concentration in murine neurological tissue, J. Anal. Atomic Spectrom. 29 (2014) 565e570. €fner, N. Griga, C. Theiss, A. Mermillod-Blondin, [8] M. Grehn, T. Seuthe, M. Ho M. Eberstein, H. Eichler, J. Bonse, Femtosecond-laser induced ablation of silicate glasses and the intrinsic dissociation energy, Opt. Mater. Express 4 (2014) 689e700. [9] D.J. Hare, J.K. Lee, A.D. Beavis, A. van Gramberg, J. George, P.A. Adlard, D.I. Finkelstein, P.A. Doble, Three-dimensional atlas of iron, copper, and zinc in the mouse cerebrum and brainstem, Anal. Chem. 84 (2012) 3990e3997. [10] B. Paul, D.J. Hare, D.P. Bishop, C. Paton, V.T. Nguyen, N. Cole, M.M. Niedwiecki, E. Andreozzi, A. Vais, J.L. Billings, L. Bray, A.I. Bush, G. McColl, B.R. Roberts, P.A. Adlard, D.I. Finkelstein, J. Hellstrom, J.M. Hergt, J.D. Woodhead, P.A. Doble, Visualising mouse neuroanatomy and function by metal distribution using laser ablation-inductively coupled plasma-mass spectrometry imaging, Chem. Sci. 6 (2015) 5383e5393. €glinger, M.K.-H. Scha €fer, [11] A. Matusch, C. Depboylu, C. Palm, B. Wu, G.U. Ho J.S. Becker, Cerebral bioimaging of Cu, Fe, Zn, and Mn in the MPTP mouse model of Parkinson's disease using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), J. Am. Soc. Mass Spectrom. 21 (2010) 161e171. [12] A. Matusch, L.S. Fenn, C. Depboylu, M. Klietz, S. Strohmer, J.A. McLean, J.S. Becker, Combined elemental and biomolecular mass spectrometry imaging for probing the inventory of tissue at a micrometer scale, Anal. Chem. 84 (2012) 3170e3178. [13] D. Pozebon, G.L. Scheffler, V.L. Dressler, M.A.G. Nunes, Review of the applications of laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) to the analysis of biological samples, J. Anal. Atomic Spectrom. 29 (2014) 2204e2228. [14] D. Pozebon, V.L. Dressler, G.L. Scheffler, Recent applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for biological sample analysis: a follow-up review, J. Anal. Atomic Spectrom. (2017), http:// dx.doi.org/10.1039/C7JA00026J (in press). [15] A.I. Bush, The metallobiology of Alzheimer's disease, Trends Neurosci. 26 (2003) 207e214.
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
Contents lists available at ScienceDirect
Analytica Chimica Acta journal homepage: www.elsevier.com/locate/aca
Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18) Dominic J. Hare a, b, * a b
Elemental Bio-imaging Facility, University of Technology Sydney, Broadway, New South Wales 2007, Australia The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
a r t i c l e i n f o Article history: Received 5 February 2017 Received in revised form 20 March 2017 Accepted 21 March 2017 Available online xxx
Contents Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00
I am writing to express concerns regarding the review article 'Bioimaging mass spectrometry of trace elements e recent advance and applications of LA-ICP-MS: A review' by J Sabine Becker and colleagues from 2014 [1]. In my opinion, this review has made some serious and unsubstantiated criticisms of work from our laboratory. Although I was aware of these issues at the time of publication, the increasing number of citations it has received over the past few years has led me to contact Analytica Chimica Acta to correct the misleading information that has now become regularly referenced as a representation of the current state of the art of laser ablationinductively coupled plasma-mass spectrometry (LA-ICP-MS) in the biological sciences. On page 14, the authors refer to our study of changes in brain cobalt levels induced by intermittent hypoxia [2]. The authors write: “Recently the same research group [2] compared brain sections of 5 common mice after 8 weeks of intermittent hypoxyia [sic] versus 6 controls. The elevation of 59Co from 62 to 5600 ng g1 localized to white matter, seems biologically highly non-plausible and may rather originate from a different batch (storage in metallic vessels) of
* Elemental Bio-imaging Facility, University of Technology Sydney, Broadway, New South Wales 2007, Australia. E-mail address: [email protected].
formalin solution used for perfusion and fixation”. I acknowledge that the reported concentrations of cobalt in the long-term intermittent hypoxic (LTIH) mouse brain are particularly high, and we ourselves were surprised at the 93-fold increase compared to animals exposed to sham intermittent hypoxic conditions, and expressed this sentiment in the report. This finding spurred on the additional experiments to understand why such an increase occurred, and these were described at length in the paper. These experiments were entirely ignored by the authors of this review, and the results were dismissed as being “biologically highly non-plausible”. We used our well-established and analyticallyvalidated matrix-matched external calibration method [3,4] and have confidence in the analytical figures reported. Although high, cobalt concentrations within the same order of magnitude have been detected in biological tissue (bovine liver) using a wellvalidated atomic absorption spectroscopy method [5]. As cobalt is an essential cofactor in vitamin B12, which is critical for processes such as one carbon metabolism in the central nervous system [6], we examined several biomarkers of impaired neurological function and vitamin B12 activity in both treatment groups. Increased cobalt concentration coincided with elevated markers of oxidative stress, damage to myelin sheaths and evidence of axonal degeneration, as well as decreased serum methylmalonic acid levels, which are indicative of increased vitamin B12 activity. This substantial evidence supports our hypothesis that long-term intermittent hypoxia increases brain vitamin B12, and that
http://dx.doi.org/10.1016/j.aca.2017.03.042 0003-2670/© 2017 Elsevier B.V. All rights reserved.
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
2
D.J. Hare / Analytica Chimica Acta xxx (2017) 1e4
elevated cobalt levels are not ‘biologically highly non-plausible’. The review authors attempted to explain the increase as potentially having “originate[d] from a different batch (storage in metallic vessels)”. This comment is entirely speculative and essentially suggests that we would be so careless as to store tissue from an experiment specifically designed to assess metal levels in metal containers, and that we had intentionally segregated the experimental groups so that only the LTIH tissue was housed in such vessels. Even if leaching of cobalt from metal containers (which would typically be stainless steel containing only trace levels of cobalt) was a plausible explanation for elevated cobalt levels, would we not also see an increase in iron levels in the treatment group? Indeed, we did measure iron, which showed no statistical difference (t ¼ 1.92; df ¼ 9; P ¼ 0.087) between groups.
Another unsubstantiated speculative reason for cobalt increase presented by the review was infiltration from the “formalin solution used for perfusion and fixation”. We have experimentally shown that transition metals universally leach out of, not in to, brain tissue during fixation and cryopreservation [7]. Unpublished data from our group has identified that cobalt is prone to this effect, retaining only 18.4 ± 1.6% of the brain's original cobalt content after prolonged fixation and cryoprotection. I also stress that in our study, both sham and LTIH brains underwent identical sample preparation steps. The claim that the increase could be “isobaric interferences at m/ z ¼ 59 may it be 40Ar18O1Hþ or 28Si31Pþ resulting from ablating glass under the sections of the treated group” is, again, baseless and incorrect. As is clear from the paper in question, experimental
Fig. 1. Sample order (a) and quantitative iron (b), copper (c) and zinc (d) maps in the mouse brain. Reprinted with permission from Hare et al. [9]. Copyright 2012 American Chemical Society.
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
D.J. Hare / Analytica Chimica Acta xxx (2017) 1e4
parameters for all imaging experiments were identical, regardless of treatment group. Additionally, the energy fluence of 0.8 J cm2 is well below the threshold required to ablate silicate glass (minimum threshold ¼ 2.4 J cm2 [8]). Considering the authors' reputation in laser ablation, it is surprising that they included this clearly incorrect statement. Taken together, all these critical points were conveniently ignored by Becker and colleagues, as they clearly did not fit the narrative they wished to present and entirely excluded the biological context of the study, which is essential if this unique analytical technique is to be fully accepted in medical research. My second major concern regarding this review appears on page 15, when the authors critique our 2012 Analytical Chemistry paper [9]: “[a]ll sections from one slide where [sic] ablated together in a single run, which further comprised three measurements of a standard series, with a non-specified number of line-scans at non specified time points. Therefore, in the series of resulting concentration maps discontinuations between the three slides are clearly discernable [sic]”. Again, the authors have taken it upon themselves to interpret our published data while conveniently ignoring the context to fit their own narrative. As is explained in the paper in question, standards were run three times over a consecutive 158-h experiment, and Becker and colleagues note that three slides of samples were analysed. It is not a major leap of logic for readers to recognise that standards were run for each ablated slide. Regarding discontinuations being clearly discernible, we assume the reviewers are referring to Fig. 2 in the original manuscript (reproduced here as Fig. 1), and it would seem that they have simply misinterpreted the order of samples, which are marked in panel A. We clearly state in our paper that standards were used for external calibration and was measured three times “to monitor and correct for signal drift” [9]. The authors of this review state that “[a]t the edges of the sections displayed concentrations are artificially high due pixel wise division by the unsmoothed 13C image exhibiting low pixel values at the edges due to partial volume effects.” Again, the interpretation of our data is
3
incorrect; if this effect was indeed due to an “unsmoothed 13C image”, would we not see the same effect for all three measured analytes? Simple inspection of Fig. 1 shows this is not the case. Finally, Becker and colleagues write “[a]lthough the 3D reconstruction was not convincing, this work enables a comprehensive understanding of the architecture of Fe and Cu throughout the mouse brain e Zn had obviously been partially washed out e and deserves online accessibility.” I appreciate and agree with the authors regarding the need for online accessible resources (the full anatomical metal atlas is available as electronic supplementary information for the paper in question), and my group has gone on to drastically improve our three-dimensional reconstruction methods [10]. I am, however, again troubled to see a completely unsubstantiated comment made with no supporting evidence, this time referring to zinc being “partially washed out”. We acknowledge, and have (as mentioned previously) experimentally demonstrated [7] that a degree of metals are lost during sample preparation, but a simple consultation of the literature would make the authors aware that some of the highest zinc concentrations appear in the cerebral neocortex, and histochemical stains used for identifying ionic zinc (Fig. 2a) show the same pattern of zinc distribution as we presented (Fig. 2b). In fact, their very own previous work (Fig. 2c and d; slightly posterior to Fig. 2b) [11,12] shows the same neuroanatomical distribution. In summary, it concerns me that this work is continued to be used as a reference for biological applications of LA-ICP-MS, considering the clear misinterpretation of work from our laboratory. At the very least I believe the authors should issue an erratum and reassess or even retract the sections in question so as to ensure that the rigorous work from myself and my peers, which was subject to the level of peer review expected of original research papers, does not continue to be misrepresented in this way. In the meantime, I direct researchers using LA-ICP-MS imaging in the biosciences to the more balanced review by Pozebon et al. [13] (as well as their very recent follow-up review [14]) when describing
Fig. 2. (a) Timm's histochemical stain for zinc (II) ions in the rat brain [15]. Reprinted with permission from Cell Press (Copyright 2003). (b) Quantitative zinc distribution at a similar anatomical level measured using LA-ICP-MS from our laboratory. Reprinted with permission from the American Chemical Society (Copyright 2012) [9]. (c) and (d) Similar quantitative images of zinc in the mouse brain produced in the laboratory of Becker and colleagues. (c) is reprinted (adapted) from Matusch et al. [12] with permission from the American Chemical Society (Copyright 2012). (d) is reprinted (adapted) from Matusch et al. [11] with permission from Springer (Copyright 2010).
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042
4
D.J. Hare / Analytica Chimica Acta xxx (2017) 1e4
the current capabilities of this technology. Acknowledgements Dr Hare is supported by a National Health and Medical Research Council Career Development Fellowship (APP1122981), with additional support from Agilent Technologies. He is also supported by an Australian Research Council Linkage Project (LP120200081) with Agilent Technologies and ESI. The Florey Institute of Neuroscience and Mental Health acknowledge the Operational Infrastructure Support from the Victorian State Government. References [1] J.S. Becker, A. Matusch, B. Wu, Bioimaging mass spectrometry of trace elements e recent advance and applications of LA-ICP-MS: a review, Anal. Chim. Acta 835 (2014) 1e18. [2] S.C. Veasey, J. Lear, Y. Zhu, J.B. Grinspan, D.J. Hare, S. Wang, D. Bunch, P.A. Doble, S.R. Robinson, Long-term intermittent hypoxia elevates cobalt levels in the brain, Sleep 36 (2013) 1471e1481. [3] D.J. Hare, J. Lear, D. Bishop, A. Beavis, P.A. Doble, Protocol for production of matrix-matched brain tissue standards for imaging by laser ablationinductively coupled plasma-mass spectrometry, Anal. Methods 5 (2013) 1915e1921. [4] D.J. Hare, B. Reedy, R. Grimm, S. Wilkins, I. Volitakis, J.L. George, R.A. Cherny, A.I. Bush, D.I. Finkelstein, P. Doble, Quantitative elemental bio-imaging of Mn, Fe, Cu and Zn in 6-hydroxydopamine induced Parkinsonism mouse models, Metallomics 1 (2009) 53e58. brega, Acid [5] G.L. Donati, C.C. Nascentes, A.R.A. Nogueira, M.A.Z. Arruda, J.A. No extraction and cloud point preconcentration as sample preparation strategies for cobalt determination in biological materials by thermospray flame furnace atomic absorption spectrometry, Microchem. J. 82 (2006) 189e195. [6] E. Reynolds, Vitamin B12, folic acid, and the nervous system, Lancet Neurol. 5 (2006) 949e960.
[7] D.J. Hare, J.L. George, L. Bray, I. Volitakis, A. Vais, T.M. Ryan, R.A. Cherny, A.I. Bush, C.L. Masters, P.A. Adlard, P.A. Doble, D.I. Finkelstein, The effect of paraformaldehyde fixation and sucrose cryoprotection on metal concentration in murine neurological tissue, J. Anal. Atomic Spectrom. 29 (2014) 565e570. €fner, N. Griga, C. Theiss, A. Mermillod-Blondin, [8] M. Grehn, T. Seuthe, M. Ho M. Eberstein, H. Eichler, J. Bonse, Femtosecond-laser induced ablation of silicate glasses and the intrinsic dissociation energy, Opt. Mater. Express 4 (2014) 689e700. [9] D.J. Hare, J.K. Lee, A.D. Beavis, A. van Gramberg, J. George, P.A. Adlard, D.I. Finkelstein, P.A. Doble, Three-dimensional atlas of iron, copper, and zinc in the mouse cerebrum and brainstem, Anal. Chem. 84 (2012) 3990e3997. [10] B. Paul, D.J. Hare, D.P. Bishop, C. Paton, V.T. Nguyen, N. Cole, M.M. Niedwiecki, E. Andreozzi, A. Vais, J.L. Billings, L. Bray, A.I. Bush, G. McColl, B.R. Roberts, P.A. Adlard, D.I. Finkelstein, J. Hellstrom, J.M. Hergt, J.D. Woodhead, P.A. Doble, Visualising mouse neuroanatomy and function by metal distribution using laser ablation-inductively coupled plasma-mass spectrometry imaging, Chem. Sci. 6 (2015) 5383e5393. €glinger, M.K.-H. Scha €fer, [11] A. Matusch, C. Depboylu, C. Palm, B. Wu, G.U. Ho J.S. Becker, Cerebral bioimaging of Cu, Fe, Zn, and Mn in the MPTP mouse model of Parkinson's disease using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), J. Am. Soc. Mass Spectrom. 21 (2010) 161e171. [12] A. Matusch, L.S. Fenn, C. Depboylu, M. Klietz, S. Strohmer, J.A. McLean, J.S. Becker, Combined elemental and biomolecular mass spectrometry imaging for probing the inventory of tissue at a micrometer scale, Anal. Chem. 84 (2012) 3170e3178. [13] D. Pozebon, G.L. Scheffler, V.L. Dressler, M.A.G. Nunes, Review of the applications of laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) to the analysis of biological samples, J. Anal. Atomic Spectrom. 29 (2014) 2204e2228. [14] D. Pozebon, V.L. Dressler, G.L. Scheffler, Recent applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for biological sample analysis: a follow-up review, J. Anal. Atomic Spectrom. (2017), http:// dx.doi.org/10.1039/C7JA00026J (in press). [15] A.I. Bush, The metallobiology of Alzheimer's disease, Trends Neurosci. 26 (2003) 207e214.
Please cite this article in press as: D.J. Hare, Commentary: Comments regarding Becker et al. (Analytica Chimica Acta, 835, 2014, 1e18), Analytica Chimica Acta (2017), http://dx.doi.org/10.1016/j.aca.2017.03.042