Neurons And Glial Cells Count: A Reasonable After Under- Followed By Overestimation

Discussion in 'Digestion, Gut Flora' started by Amazoniac, Oct 12, 2019.

  1. Amazoniac

    Amazoniac Member

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    Dear microbial marionettes,

    One of these links has been posted elsewhere, but I figured that they was interesting enough to deserve a topic. If you prefer accuracy or feel that my interpretation in prolactinese is an insult that you don't have to put up with, ignore it and read from the source instead (they have interesting germs regardless if you're into microbiology):

    - Are We Really Vastly Outnumbered? Revisiting the Ratio of Bacterial to Host Cells in Humans
    - Revised Estimates for the Number of Human and Bacteria Cells in the Body

    It's really, really, reeeally important for you to verify the expotent, 12 is different than 13, which in turn is different than 14, consequently 14 is not the same as 12, and 11 is 12 minus 1. But the cyst is that they went from neglecting to overestimating these counts, possibly not out of distraction:

    "Bacteria are found in many parts of the human body primarily on the external and internal surfaces, including the gastrointestinal tracts, skin, saliva, oral mucosa, and conjunctiva. The vast majority of commensal bacteria reside in the colon, with previous estimates of about 10^14 bacteria (Savage, 1977), followed by the skin, which is estimated to harbor ∼10^12 bacteria (Berg, 1996). Less than 10^12 bacteria populate the rest of the body (Berg, 1996, Tannock, 1995). Within the alimentary tract, the colon is the dominant contributor to the total bacterial population, while the stomach and small intestine make negligible contributions. As a result, the colon is the focus for estimating the number of bacteria in the body. Almost all recent papers in the field of gut microbiota directly or indirectly rely on a single paper (Savage, 1977) discussing the overall number of bacteria in the gut. Interestingly, review of the original paper (Savage, 1977) demonstrates that it actually cites another paper for the estimate (Luckey, 1972). The citation lineage for a few representative cases, tracking back to the original calculation, is illustrated in Figure 1A. The progenitor paper performed an order-of-magnitude estimate by assuming 10^11 bacteria per gram and 1 L (or about 1 kg) of alimentary tract capacity. The estimate, performed by Luckey in 1972, is an illuminating example of a back-of-the-envelope estimate, which was elegantly performed, yet was probably never meant to serve as the cornerstone reference number to be cited decades later."​

    10^11/g and about 1000 g adds the 3 orders of magnetism to it. They focus on the large brain because it's by far the major site:

    "Bacteria overwhelmingly outnumber eukaryotes and archaea in the human microbiome by 2–3 orders of magnitude [7,8]. We therefore sometimes operationally refer to the microbial cells in the human body as bacteria. The diversity in locations where microbes reside in the body makes estimating their overall number daunting. Yet, once their quantitative distribution shows the dominance of the colon as discussed below, the problem becomes much simpler. The vast majority of the bacteria reside in the colon, with previous estimates of about 10^14 bacteria [2], followed by the skin, which is estimated to harbor ~10^12 bacteria [9]."

    "Table 1 shows typical order of magnitude estimates for the number of bacteria that reside in different organs in the human body. The estimates are based on multiplying measured concentrations of bacteria by the volume of each organ [9,10]. Values are rounded up to give an order of magnitude upper bound."

    "Although the bacterial concentrations in the saliva and dental plaque are high, because of their small volume the overall numbers of bacteria in the mouth are less than 1% of the colon bacteria number. The concentration of bacteria in the stomach and the upper 2/3 of the small intestine (duodenum and jejunum) is only 10^3–10^4 bacteria/mL, owing to the relatively low pH of the stomach and the fast flow of the content through the stomach and the small intestine [10]. Table 1 reveals that the bacterial content of the colon exceeds all other organs by at least two orders of magnitude. Importantly, within the alimentary tract, the colon is the only substantial contributor to the total bacterial population, while the stomach and small intestine make negligible contributions."​

    Deduction one-zero-one: if the gut is considered one of our brains and it contains cells, what are these specific cells?

    This summarizes their revision to get the ratio down to near 1 (rather than being outnumbered by factors):

    upload_2019-10-12_11-18-51.png

    The divergence in cell count between non-self to self lessons once you consider a more realistic volume for large brain and a better picture of our cell count.

    I think it's unfair for them to use humans as denominator because when you compare our appropriated neurons and glial cells in our secondary brain to those residing in our primary brain, it's clear who's charge, we can consider ourselves marionettes.

    upload_2019-10-12_11-19-11.png
    upload_2019-10-12_11-19-26.png

    They estimated a total human cell count of 30×10^12, with 0.6% being neurons and glial cells in our secondary brain, something like 1.8×10^11 [or 2× their 8.5×10^10]. Now compare it with 3.8×10^13.

    I don't believe we (the oppressed minority) are dumber as they imply:

    upload_2019-10-12_11-20-15.png

    That's adsurb, we don't need anatomy on our side, we can make better use of our fewer cognitive cells to win this sex war once and for all. To all men reading this, use fine chocolate to attract the victims and fill it with cascara sagrada, meanwhile abstain from defecation (or in other words, practice nocrap) because it's a viable way to increase neurons, glial cells, and so intelligence:

    "An adult human is reported to produce on average 100–200 grams of wet stool per day [18]. The colonic transit time is negatively correlated with the daily fecal output, and its normal values are about 25–40 hours [18,19]. By multiplying the daily output and the colon transit time, we thus get a volume estimate of 150–250 mL, which is somewhat lower than but consistent with the values above, given the uncertainties and very crude estimate that did not account for water in the colon that is absorbed before defecation. To summarize, the volume of colon content as evaluated by recent analyses of MRI images is in keeping with previous estimates and fecal transit dynamics. Values for a reference adult man averaged 0.4 L (standard error of the mean [SEM] 17%, coefficient of variation [CV] 25%), which will be used in calculations []. Following a typical meal, the volume changes by about 10% [15], while each defecation event reduces the content by a quarter to a third [18]."

    "From the total colon content of about 0.4 kg and a bacteria mass fraction of about one-half [21,24], we get a contribution of about 0.2 kg (wet weight) from bacteria to the overall mass of the colon content. Given the dominance of bacteria in the colon over all other microbiota populations in the body, we conclude that there is about 0.2 kg of bacteria in the body overall. Given the water content of bacteria, the total dry weight of bacteria in the body is about 50–100g. This value is consistent with a parallel alternative estimate for the total mass of bacteria that multiplies the average mass of a gut bacterium of about 5 pg (wet weight, corresponding to a dry weight of 1–2 pg, see S1 Appendix) with the updated total number of bacteria. We note that this empirically observed average gut bacterium is several times bigger than the conveniently chosen “standard” 1 μm3 volume and 1 pg wet mass bacterium often referred to in textbooks. The total bacteria mass we find represents about 0.3% of the overall body weight, significantly updating previous statements that 1%–3% of the body mass is composed of bacteria or that a normal human hosts 1–3 kg of bacteria [25]."​

    upload_2019-10-12_11-20-29.png
     
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