Histamine

evidence_access

Primary full text

experimental_model

Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays.

limitations

Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

The same histidine-derived messenger can activate a distinct receptor route.

primary_references

Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 226–232

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. · source_derived_draft · unverified_draft

## histidine-h1-activation The same histidine-derived messenger can activate a distinct receptor route. Histamine-bound human H1 receptor was resolved with an engineered Gq-family protein complex, with binding and functional mutagenesis supporting ligand recognition and coupling. Model: Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. Limitations: Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response. Evidence access: Primary full text Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

evidence_access

Primary full text

experimental_model

Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays.

limitations

Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

The same histidine-derived messenger can activate a distinct receptor route.

primary_references

Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 234–240

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. · source_derived_draft · unverified_draft

## histidine-h2-activation The same histidine-derived messenger can activate a distinct receptor route. Histamine-bound human H2 receptor was resolved with an engineered Gs-family protein complex, with binding and functional mutagenesis supporting ligand recognition and coupling. Model: Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. Limitations: Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response. Evidence access: Primary full text Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

evidence_access

Primary full text

experimental_model

Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays.

limitations

Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

The same histidine-derived messenger can activate a distinct receptor route.

primary_references

Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 242–248

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. · source_derived_draft · unverified_draft

## histidine-h3-activation The same histidine-derived messenger can activate a distinct receptor route. Histamine-bound human H3 receptor was resolved with an engineered Gi-family protein complex, with binding and functional mutagenesis supporting ligand recognition and coupling. Model: Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. Limitations: Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response. Evidence access: Primary full text Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

evidence_access

Primary full text

experimental_model

Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays.

limitations

Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

The same histidine-derived messenger can activate a distinct receptor route.

primary_references

Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 250–256

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. · source_derived_draft · unverified_draft

## histidine-h4-activation The same histidine-derived messenger can activate a distinct receptor route. Histamine-bound human H4 receptor was resolved with an engineered Gi-family protein complex, with binding and functional mutagenesis supporting ligand recognition and coupling. Model: Engineered human receptor complexes produced in insect cells, cryo-EM and HEK293 binding/G-protein assays. Limitations: Structural stabilization, chimeric/mini G proteins and recombinant cells differ from native tissues; receptor engagement is not proof that oral histidine produces this response. Evidence access: Primary full text Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

evidence_span

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experimental_model

Crystallography of recombinant human diamine oxidase and inhibitor complexes

exposure

Native structure and inhibitor binding

limitations

Copper/TPQ dependence is molecular evidence, not a trial of copper for histamine intolerance; DAO activity can have multiple determinants.

nutrient_topic

Copper research collection; topical membership is not evidence of a direct dietary effect. · Copper

organism

Human AOC1 expressed in insect cells

plain_language

Related copper enzymes process different amines.

primary_references

[copper-p19764817] Structure and inhibition of human diamine oxidase. (2009). https://pubmed.ncbi.nlm.nih.gov/19764817/ DOI: 10.1021/bi9014192

tissue_or_cell_type

Purified protein

Copper: transport, cuproenzymes, deficiency, excess and nutrient interactions (2026-09-17) · lines 1027–1038

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Crystallography of recombinant human diamine oxidase and inhibitor complexes · source_derived_draft · unverified_draft

### copper-aoc1-histamine-specificity Human diamine oxidase has a substrate pocket adapted to diamines including histamine, distinct from that of AOC3. Condition category: normal nutrient_topic: Copper research collection; topical membership is not evidence of a direct dietary effect. plain_language: Related copper enzymes process different amines. organism: Human AOC1 expressed in insect cells tissue_or_cell_type: Purified protein experimental_model: Crystallography of recombinant human diamine oxidase and inhibitor complexes limitations: Copper/TPQ dependence is molecular evidence, not a trial of copper for histamine intolerance; DAO activity can have multiple determinants. exposure: Native structure and inhibitor binding evidence_span: {"source_cache": "artifacts/copper-research/19764817.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9a01d0dba5caec8a33a77fdbe7190d7a05bdd6e691a570a890eb6b19d4c692b6", "start_char": 0, "end_char": 1343, "text_sha256": "9a01d0dba5caec8a33a77fdbe7190d7a05bdd6e691a570a890eb6b19d4c692b6"} [copper-p19764817] Structure and inhibition of human diamine oxidase. (2009). https://pubmed.ncbi.nlm.nih.gov/19764817/ DOI: 10.1021/bi9014192

experimental_model

Recombinant engineered human HDC; crystallography and enzyme assays

exposure

Recombinant HDC enzyme-activity assays.

limitations

Engineered soluble HDC construct; histamine release and allergy outcomes were not tested.

nutrient_topic

Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6

organism

Homo sapiens

plain_language

Activated B6 supports histamine synthesis.

primary_references

[komori-2012-hdc] Structural Study Reveals That Ser-354 Determines Substrate Specificity on Human Histidine Decarboxylase (2012). https://pmc.ncbi.nlm.nih.gov/articles/PMC3436558/ DOI: 10.1074/jbc.M112.381897

tissue_or_cell_type

Purified recombinant protein; no intact tissue

Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1047–1057

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant engineered human HDC; crystallography and enzyme assays · source_derived_draft · unverified_draft

### b6-neuro-hdc-histamine Recombinant human HDC catalyzes PLP-dependent histidine decarboxylation to histamine. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Activated B6 supports histamine synthesis. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant engineered human HDC; crystallography and enzyme assays limitations: Engineered soluble HDC construct; histamine release and allergy outcomes were not tested. exposure: Recombinant HDC enzyme-activity assays. [komori-2012-hdc] Structural Study Reveals That Ser-354 Determines Substrate Specificity on Human Histidine Decarboxylase (2012). https://pmc.ncbi.nlm.nih.gov/articles/PMC3436558/ DOI: 10.1074/jbc.M112.381897

evidence_access

Primary abstract

experimental_model

Human mast-cell cultures; 1–100 micromolar pretreatment.

limitations

Do not assign the analog’s animal or calcium results to luteolin.

nutrient_topic

Luteolin collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Luteolin / 3′,4′,5,7-tetrahydroxyflavone

plain_language

Related flavones have different potencies.

primary_references

The novel flavone tetramethoxyluteolin is a potent inhibitor of human mast cells. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25498791/ · DOI 10.1016/j.jaci.2014.10.032

Luteolin: metabolism, immune signaling, redox chemistry and cross-nutrient mechanisms (2026-09-19) · lines 388–394

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human mast-cell cultures; 1–100 micromolar pretreatment. · source_derived_draft · unverified_draft

## luteolin-mast-histamine Related flavones have different potencies. Luteolin reduced stimulated histamine release from human LAD2 mast cells; tetramethoxyluteolin was more potent. Model: Human mast-cell cultures; 1–100 micromolar pretreatment. Limitations: Do not assign the analog’s animal or calcium results to luteolin. Evidence access: Primary abstract The novel flavone tetramethoxyluteolin is a potent inhibitor of human mast cells. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25498791/ · DOI 10.1016/j.jaci.2014.10.032

evidence_access

Primary abstract

experimental_model

Human basophilic leukemia KU812 cells; 15-minute pretreatment, PMA 20 nM plus A23187 1 micromolar.

limitations

Sludge-derived research material is not a dietary ingredient recommendation. This does not establish human allergy treatment or direct calcium chelation.

nutrient_topic

Fulvic acid collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · Fulvic acid (heterogeneous humic fraction)

plain_language

One preparation reduced triggered mediator release.

primary_references

Microarray analysis of immediate-type allergy in KU812 cells in response to fulvic acid. · 2011 · https://pubmed.ncbi.nlm.nih.gov/21331654/ · DOI 10.1007/s10616-010-9333-6

Fulvic acid: mixture identity, mineral chemistry, signaling and cross-nutrient mechanisms (2026-09-19) · lines 108–114

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human basophilic leukemia KU812 cells; 15-minute pretreatment, PMA 20 nM plus A23187 1 micromolar. · source_derived_draft · unverified_draft

## fulvic-acid-histamine One preparation reduced triggered mediator release. SS-FA at 0.1-10 micrograms/mL reduced PMA/calcium-ionophore-induced histamine release from KU812 cells. Model: Human basophilic leukemia KU812 cells; 15-minute pretreatment, PMA 20 nM plus A23187 1 micromolar. Limitations: Sludge-derived research material is not a dietary ingredient recommendation. This does not establish human allergy treatment or direct calcium chelation. Evidence access: Primary abstract Microarray analysis of immediate-type allergy in KU812 cells in response to fulvic acid. · 2011 · https://pubmed.ncbi.nlm.nih.gov/21331654/ · DOI 10.1007/s10616-010-9333-6

evidence_access

Primary abstract

experimental_model

Human cord-blood-derived mast cells; 15-minute pretreatment, 0.01–100 micromolar tested.

limitations

No oral allergy trial; reduced phosphorylation is not direct kinase inhibition.

nutrient_topic

Myricetin collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Myricetin

plain_language

The allergic response involves multiple independently recorded steps.

primary_references

Flavonols inhibit proinflammatory mediator release, intracellular calcium ion levels and protein kinase C theta phosphorylation in human mast cells. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15912140/ · DOI 10.1038/sj.bjp.0706246

Myricetin: metabolism, immune signaling, redox chemistry and cross-nutrient mechanisms (2026-09-19) · lines 420–426

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human cord-blood-derived mast cells; 15-minute pretreatment, 0.01–100 micromolar tested. · source_derived_draft · unverified_draft

## myricetin-mast-histamine The allergic response involves multiple independently recorded steps. Myricetin inhibited anti-IgE-stimulated histamine release from cultured human cord-blood mast cells. Model: Human cord-blood-derived mast cells; 15-minute pretreatment, 0.01–100 micromolar tested. Limitations: No oral allergy trial; reduced phosphorylation is not direct kinase inhibition. Evidence access: Primary abstract Flavonols inhibit proinflammatory mediator release, intracellular calcium ion levels and protein kinase C theta phosphorylation in human mast cells. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15912140/ · DOI 10.1038/sj.bjp.0706246

dose

Tartrazine 0.1-1 mM with calcium ionophore A23187

duration

Maximum augmentation with 0-5 min preincubation

evidence_access

Primary PubMed abstract; unrecovered method details explicitly retained.

evidence_scope

literature_reviewed; source-specific experimental curation

experimental_model

Purified rat peritoneal mast cells

limitations

The ionophore interaction cannot be generalized to every mast-cell stimulus; higher concentrations had a small inhibitory effect.

nutrient_topic

Tartrazine food-colorant chapter; nutrient, drug and peptide interactions retain their models and limits. · Tartrazine

organism

Purified rat peritoneal mast cells

plain_language

Tartrazine at 0.1-1 mM augmented A23187-triggered histamine release in the rat mast-cell assay.

primary_references

The effect of tartrazine on histamine release from rat peritoneal mast cells. (1984). https://pubmed.ncbi.nlm.nih.gov/6204951/ DOI: 10.1016/0192-0561(84)90021-3

route

In vitro preincubation and challenge

tissue

Calcium-ionophore-triggered histamine release

Tartrazine: mechanisms, molecular forms and cross-actor connections (2026-09-20) · lines 468–477

Original AI-assisted curation of eighteen primary studies. Study-specific citations, negative findings and limitations retained. Not publisher full text. · supports · Purified rat peritoneal mast cells · source_derived_draft · unverified_draft

## tartrazine-mast-cell-augmentation Tartrazine at 0.1-1 mM augmented A23187-triggered histamine release in the rat mast-cell assay. Model/species: Purified rat peritoneal mast cells Tissue: Calcium-ionophore-triggered histamine release Exposure: Tartrazine 0.1-1 mM with calcium ionophore A23187 Route: In vitro preincubation and challenge Duration: Maximum augmentation with 0-5 min preincubation Limits: The ionophore interaction cannot be generalized to every mast-cell stimulus; higher concentrations had a small inhibitory effect. Primary reference: The effect of tartrazine on histamine release from rat peritoneal mast cells. (1984). https://pubmed.ncbi.nlm.nih.gov/6204951/ DOI: 10.1016/0192-0561(84)90021-3 Access: Primary PubMed abstract; unrecovered method details explicitly retained.

dose

Tartrazine 10 micromolar-10 mM with compound 48/80 or egg-albumin challenge

duration

Acute release assay; antigen inhibition strongest with simultaneous addition

evidence_access

Primary PubMed abstract; unrecovered method details explicitly retained.

evidence_scope

literature_reviewed; source-specific experimental curation

experimental_model

Purified rat peritoneal mast cells

limitations

Secretagogue and timing alter the response. This is not a demonstration of spontaneous histamine release or a human allergic mechanism.

nutrient_topic

Tartrazine food-colorant chapter; nutrient, drug and peptide interactions retain their models and limits. · Tartrazine

organism

Purified rat peritoneal mast cells

plain_language

Tartrazine inhibited compound-48/80- and antigen-triggered histamine release from rat peritoneal mast cells.

primary_references

The effect of tartrazine on histamine release from rat peritoneal mast cells. (1984). https://pubmed.ncbi.nlm.nih.gov/6204951/ DOI: 10.1016/0192-0561(84)90021-3

route

In vitro co-exposure

tissue

Secretagogue-induced histamine release

Tartrazine: mechanisms, molecular forms and cross-actor connections (2026-09-20) · lines 457–466

Original AI-assisted curation of eighteen primary studies. Study-specific citations, negative findings and limitations retained. Not publisher full text. · supports · Purified rat peritoneal mast cells · source_derived_draft · unverified_draft

## tartrazine-mast-cell-inhibition Tartrazine inhibited compound-48/80- and antigen-triggered histamine release from rat peritoneal mast cells. Model/species: Purified rat peritoneal mast cells Tissue: Secretagogue-induced histamine release Exposure: Tartrazine 10 micromolar-10 mM with compound 48/80 or egg-albumin challenge Route: In vitro co-exposure Duration: Acute release assay; antigen inhibition strongest with simultaneous addition Limits: Secretagogue and timing alter the response. This is not a demonstration of spontaneous histamine release or a human allergic mechanism. Primary reference: The effect of tartrazine on histamine release from rat peritoneal mast cells. (1984). https://pubmed.ncbi.nlm.nih.gov/6204951/ DOI: 10.1016/0192-0561(84)90021-3 Access: Primary PubMed abstract; unrecovered method details explicitly retained.

evidence_access

Primary full text

experimental_model

Recombinant human receptor mutagenesis and G-protein dissociation assays.

limitations

Do not label H2 as exclusively Gs-coupled; chimera-supported structure and native Gq signaling are distinct evidence types.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

A receptor can use more than one signaling partner, with separable structural requirements.

primary_references

Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 258–264

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Recombinant human receptor mutagenesis and G-protein dissociation assays. · source_derived_draft · unverified_draft

## histidine-h2-coupling-selectivity A receptor can use more than one signaling partner, with separable structural requirements. Human H2 receptor W222A/V mutations abolished measured Gs activation while retaining Gq responses; the structural Gq complex used a G-alpha-s/q chimera. Model: Recombinant human receptor mutagenesis and G-protein dissociation assays. Limitations: Do not label H2 as exclusively Gs-coupled; chimera-supported structure and native Gq signaling are distinct evidence types. Evidence access: Primary full text Structural basis of ligand recognition and activation of the histamine receptor family. · 2024 · https://pubmed.ncbi.nlm.nih.gov/39333117/ · DOI 10.1038/s41467-024-52585-y

evidence_access

Primary abstract

experimental_model

Purified recombinant human enzyme; ternary structures and steady-state kinetics.

limitations

A shared SAM requirement does not prove clinically important methyl depletion from histamine turnover.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

Histamine disposal connects to the cellular methyl-donor system.

primary_references

Two polymorphic forms of human histamine methyltransferase: structural, thermal, and kinetic comparisons. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11566133/ · DOI 10.1016/s0969-2126(01)00643-8

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 210–216

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified recombinant human enzyme; ternary structures and steady-state kinetics. · source_derived_draft · unverified_draft

## histidine-hnmt-methylation Histamine disposal connects to the cellular methyl-donor system. Human HNMT methylates histamine using SAM; structural complexes locate histamine and the reaction product SAH at the enzyme. Model: Purified recombinant human enzyme; ternary structures and steady-state kinetics. Limitations: A shared SAM requirement does not prove clinically important methyl depletion from histamine turnover. Evidence access: Primary abstract Two polymorphic forms of human histamine methyltransferase: structural, thermal, and kinetic comparisons. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11566133/ · DOI 10.1016/s0969-2126(01)00643-8

evidence_access

Primary abstract

experimental_model

Human recombinant enzyme comparison.

limitations

Results paragraph reports increased Km; the abstract conclusion says lowered Km. Numerical results are retained as a source wording discrepancy, not two independent experiments. No clinical symptom prediction.

nutrient_topic

L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Histidine

plain_language

A common enzyme variant changed the measured reaction kinetics.

primary_references

Two polymorphic forms of human histamine methyltransferase: structural, thermal, and kinetic comparisons. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11566133/ · DOI 10.1016/s0969-2126(01)00643-8

L-Histidine: supply, catabolism, histamine, receptors and cross-nutrient mechanisms (2026-09-19) · lines 218–224

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human recombinant enzyme comparison. · source_derived_draft · unverified_draft

## histidine-hnmt-variant A common enzyme variant changed the measured reaction kinetics. Recombinant Ile105 HNMT had about 16 percent lower specific activity and higher apparent Km for SAM and histamine than Thr105 across 25-45 degrees C. Model: Human recombinant enzyme comparison. Limitations: Results paragraph reports increased Km; the abstract conclusion says lowered Km. Numerical results are retained as a source wording discrepancy, not two independent experiments. No clinical symptom prediction. Evidence access: Primary abstract Two polymorphic forms of human histamine methyltransferase: structural, thermal, and kinetic comparisons. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11566133/ · DOI 10.1016/s0969-2126(01)00643-8

evidence_access

Primary abstract

experimental_model

Mouse cerebral ischemia with Hdc knockout.

limitations

Preclinical intervention; not stroke treatment guidance.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Protection in this model did not require histamine synthesis.

primary_references

Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 460–466

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse cerebral ischemia with Hdc knockout. · source_derived_draft · unverified_draft

## carnosine-ischemia-hdc Protection in this model did not require histamine synthesis. Carnosine treatment reduced infarct size in both wild-type and histidine-decarboxylase-null mice after permanent MCAO. Model: Mouse cerebral ischemia with Hdc knockout. Limitations: Preclinical intervention; not stroke treatment guidance. Evidence access: Primary abstract Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021