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Record W7132927866

Ionic and pH homeostasis in metabolically active compartments

2003· dissertation· W7132927866 on OpenAlexaff
Andrzej Jankowski

Bibliographic record

VenueTSpace · 2003
Typedissertation
Language
FieldMedicine
TopicHydrogen's biological and therapeutic effects
Canadian institutionsBank of Canada
Fundersnot available
KeywordsCytosolNADPH oxidaseMembraneHomeostasisDepolarizationEffluxOxygenMembrane potentialOxidative phosphorylation
DOInot available

Abstract

fetched live from OpenAlex

Maintenance of a stable hydrogen ion concentration ([H +]) is important in cells that have high metabolic rates, since they have elevated rates of hydrogen ion generation. One of such model systems are white blood cells, specifically polymorphonuclear leukocytes. These cells represent the very first line of protection against infections. In neutrophils during pathogen-induced oxygen consumption the cytosol concurrently experiences massive H+ generation. Failure to maintain a stable cytosolic pH would result in a decreased oxidative burst, inhibition of cellular migration and lower rates of phagocytosis. These protons can be eliminated either by consumption by buffering components and dismutation reactions or by extrusion across the plasma membrane. Efflux of protons can, in principle, be mediated through a H+ -conductive pathway that is expressed in neutrophils at high levels. The H+ conductance was postulated to be activated primarily by large depolarizations of the plasma membrane. I devised a new method to precisely measure the extent of depolarization of the plasma membrane resulting from neutrophil activation. Using soluble fluorescent probes and spectrofluorimetry, I managed to obtain reproducible measurements of membrane potential (E m = +58 ± 6 mV) in activated human neutrophils. The results suggest that H+-conductance contributes to the acid-base homeostasis during leukocyte activation. The pH regulation in leukocytes is critical also in the phagocytic vacuole. Using improved methods I have confirmed that phagosomal pH in neutrophils is neutral. I have established that the insertion of V-ATPases into the phagosomal membrane was reduced, and that passive proton (equivalent) permeability of the phagosomal membrane increased when the oxidase is active. These observations suggest that neutrophils rely mostly on bacteriostatic activity of reactive oxygen species rather than acidic hydrolazes. Finally, I have developed a novel method targeting a pH-sensitive fluorescent protein specifically to the peroxisomal lumen. This allowed me in detail re-examine the luminal pH of peroxisomes. Based on this non-invasive approach I have identified that peroxisomal pH was 6.9, resembling that of the cytosol. Further examination showed, that peroxisomes do not regulate their pH independently. Their large H+ (equivalents) permeability connects them with the buffer reservoir of the cytoplasm and with the homeostatic mechanisms that control cytosolic pH.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesMeta-epidemiology (narrow), Insufficient payload (model declined to judge)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.653
Threshold uncertainty score1.000

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0010.001
Meta-epidemiology (broad)0.0010.000
Bibliometrics0.0000.001
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0010.001
Insufficient payload (model declined to judge)0.0010.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.029
GPT teacher head0.363
Teacher spread0.334 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

Study designObservational
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations0
Published2003
Admission routes1
Has abstractyes

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