# Volume Seven — theories 1-6 (new file)
THEORIES = [
{
 "n": 1,
 "slug": "barrier-fails-at-a-phase-transition",
 "field": "Dermatology & Skin Barrier",
 "kind": "Skin biophysics",
 "title": "The Barrier Fails at a Phase Transition",
 "claim": "Skin barrier function collapses when the intercellular lipids undergo a phase transition rather than when the layer thins, so permeability should change sharply at a critical temperature and hydration, and emollients should work by shifting that transition.",
 "dek": "Barrier creams are formulated to add oil. The barrier may care about which phase the oil is in.",
 "evidence": [
   ("Fine tuning of the skin barrier has been linked to a low-temperature lipid chain transition, with barrier properties changing at the transition rather than gradually with lipid amount.",
    "https://www.sciencedirect.com/science/article/pii/S0022202X23024004", "Journal of Investigative Dermatology"),
   ("The phase behaviour of skin-barrier lipids has been characterised by combined experiment and simulation, which locates the transition and shows that permeability depends on the phase rather than only on composition.",
    "https://www.sciencedirect.com/science/article/pii/S0006349524004776", "Biophysical Journal"),
 ],
 "tension": "Barrier function is modelled as a diffusion problem through a lipid layer, with permeability proportional to thickness and lipid composition. That model explains slow changes and misses the abrupt ones, and formulation is guided by composition rather than by phase.",
 "theory": [
   "The stratum corneum lipids form ordered lamellae. In the ordered phase, water diffuses slowly along a tortuous path; in the disordered phase, the path is shorter and permeability rises sharply.",
   "Because a phase transition is cooperative, the change is abrupt at a critical temperature or hydration rather than gradual. That makes barrier failure a threshold phenomenon, and it predicts that two skins with the same lipid composition but different phase states will differ in permeability.",
   "The prediction is that transepidermal water loss should change discontinuously with temperature at the transition, and that emollients which shift the transition temperature should improve barrier function without changing lipid quantity.",
   "The formulation consequence is that phase behaviour, not oil content, should be the design target, and that a product which disorders the lipids can make the barrier worse while feeling better."
 ],
 "prior": ("Composition-and-thickness barrier models",
           "Those models make permeability a function of how much lipid is present. This makes it a function of which phase the lipid is in, which predicts abrupt changes that composition cannot explain."),
 "predictions": [
   ("P1", "Water loss should change discontinuously at the lipid transition temperature."),
   ("P2", "Emollients shifting the transition should improve barrier function at constant lipid content."),
   ("P3", "Skins matched on composition but differing in phase should differ in permeability."),
 ],
 "refute": "Permeability changing smoothly with composition and thickness, with no discontinuity at the transition, would leave the diffusion model adequate.",
 "change": "It would make phase behaviour the formulation target in dermatology.",
 "sources": [
   ("Skin barrier fine tuning through low-temperature lipid chain transition — JID", "https://www.sciencedirect.com/science/article/pii/S0022202X23024004"),
   ("Phase behaviour of skin-barrier lipids — Biophysical Journal", "https://www.sciencedirect.com/science/article/pii/S0006349524004776"),
 ],
},
{
 "n": 2,
 "slug": "wounds-heal-by-current",
 "field": "Dermatology & Skin Barrier",
 "kind": "Wound healing",
 "title": "Wounds Heal by Current",
 "claim": "Wound healing is driven by an endogenous electric field rather than by chemical gradients alone, so healing rate should be predicted by the wound current and accelerated by applied fields, and drugs that block epithelial ion transport should delay closure.",
 "dek": "A cut shorts out the skin's battery. The current that flows may be the signal that says where to crawl.",
 "evidence": [
   ("Electric fields have been characterised as a key signal in wound healing, with epithelial cells migrating directionally in response to the field that arises when the epithelium is breached.",
    "https://www.sciencedirect.com/science/article/pii/S209669112100090X", "Electric field in wound healing"),
   ("Sedentary keratinocytes at the wound edge migrate into the wound guided by the endogenous electric field, which is a directional cue that chemical gradients alone do not supply.",
    "https://pesquisa.bvsalud.org/fiocruz/?lang=pt&q=au:%22Pullar,%20Christine%20E%22", "Keratinocyte electrotaxis"),
 ],
 "tension": "Wound healing is modelled with chemical gradients: growth factors, cytokines, and chemotaxis. Those factors are real and they do not explain directionality at the wound edge, because a diffusing factor has no inherent polarity once the source is distributed along the margin.",
 "theory": [
   "Intact epithelium maintains a transepithelial potential. When it is breached, current flows out of the wound, creating a steady field whose direction points into the wound and whose magnitude falls with distance.",
   "Cells migrate up the field. The field therefore provides a vector that chemistry cannot, and the rate of closure should scale with the field strength rather than with the concentration of any single factor.",
   "The prediction is that healing rate should correlate with wound current better than with cytokine levels, that applied fields should accelerate closure, and that blocking ion transport should slow it even when growth factors are normal.",
   "The clinical consequence is that electrical stimulation, which has been used empirically for decades, would have a mechanism and a dosing rationale, and that dressings should be designed not to short the field."
 ],
 "prior": ("Chemotaxis-led healing models",
           "Those models explain attraction but not direction. This explains direction with a field, which predicts acceleration from applied current and delay from ion-transport blockade."),
 "predictions": [
   ("P1", "Healing rate should correlate with wound current better than with cytokine levels."),
   ("P2", "Applied fields should accelerate closure."),
   ("P3", "Ion-transport blockade should delay healing at normal growth factor levels."),
 ],
 "refute": "Healing rate independent of field strength at controlled chemistry would leave chemotaxis in charge.",
 "change": "It would give electrical stimulation a mechanism and a dose, and change dressing design.",
 "sources": [
   ("Electric field: a key signal in wound healing", "https://www.sciencedirect.com/science/article/pii/S209669112100090X"),
   ("Keratinocyte electrotaxis at the wound edge — publication record", "https://pesquisa.bvsalud.org/fiocruz/?lang=pt&q=au:%22Pullar,%20Christine%20E%22"),
 ],
},
{
 "n": 3,
 "slug": "acne-is-sebum-flux",
 "field": "Dermatology & Skin Barrier",
 "kind": "Sebaceous biology",
 "title": "Acne Is a Sebum Flux Problem",
 "claim": "Acne is driven by sebum production rate rather than by bacterial colonisation, so sebum suppression should be the primary intervention and antibiotics should be understood as adjuncts that work partly through anti-inflammatory effects.",
 "dek": "Acne is treated with antibiotics and blamed on a bacterium. The bacterium may be a passenger in a duct that is running too rich.",
 "evidence": [
   ("The primary role of sebum in the pathophysiology of acne vulgaris has been reviewed together with its therapeutic relevance, placing sebum production upstream of colonisation and inflammation.",
    "https://www.tandfonline.com/doi/full/10.1080/09546634.2023.2296855", "Journal of Dermatological Treatment"),
   ("Sebum amount and composition change the follicular environment, which is the mechanism by which a flux change could drive the condition rather than a bacterial change.",
    "https://www.tandfonline.com/doi/full/10.1080/09546634.2023.2296855", "Sebum and follicular environment"),
 ],
 "tension": "Acne is framed as a bacterial disease, and antibiotics are the mainstay. Resistance is rising, and the response to antibiotics is often faster than the change in bacterial load would predict, which suggests the drug is acting on something other than the bacterium.",
 "theory": [
   "Sebaceous glands deliver sebum into a narrow follicle. When production is high, the follicle becomes relatively hypoxic and the sebum composition shifts, which creates the environment in which colonisation and inflammation occur.",
   "If flux is upstream, then the bacterium is a consequence rather than a cause. That predicts that sebum suppression should work regardless of bacterial strain, and that antibiotics should work partly through anti-inflammatory action rather than through killing.",
   "The prediction is that sebum production rate should predict disease severity better than bacterial load, and that interventions lowering flux should outperform antibiotics in the long run while resistance rises.",
   "The practical consequence is that sebum measurement should guide treatment, and that antibiotic courses should be short and adjunctive rather than the foundation."
 ],
 "prior": ("Bacterial-pathogenesis models",
           "Those models make colonisation the cause. This makes sebum flux the cause and colonisation a consequence, which explains why antibiotics work faster than the bacterial change."),
 "predictions": [
   ("P1", "Sebum production rate should predict severity better than bacterial load."),
   ("P2", "Sebum suppression should work across strains."),
   ("P3", "Antibiotic response should exceed what the bacterial change explains."),
 ],
 "refute": "Severity tracking bacterial load at controlled sebum flux would restore the bacterial account.",
 "change": "It would make sebum the target and shorten antibiotic courses.",
 "sources": [
   ("The primary role of sebum in the pathophysiology of acne vulgaris", "https://www.tandfonline.com/doi/full/10.1080/09546634.2023.2296855"),
 ],
},
{
 "n": 4,
 "slug": "caries-is-a-ph-threshold",
 "field": "Dentistry & Oral Biology",
 "kind": "Oral microbiology",
 "title": "Caries Is a Threshold, Not a Dose",
 "claim": "Dental caries occurs only below a critical plaque pH that depends on the saturation of calcium and phosphate, so caries risk should be predicted from the pH threshold and the mineral saturation rather than from sugar exposure or bacterial counts.",
 "dek": "Sugar is counted in grams. The tooth responds to a number on the pH scale.",
 "evidence": [
   ("The caries process has been described as beginning when dietary sugar is metabolised by acidogenic bacteria in the biofilm, with the resulting pH drop driving demineralisation of enamel.",
    "https://jada.ada.org/article/S0002-8177%2814%2963879-4/fulltext", "Journal of the American Dental Association"),
   ("The process is reversible while the pH recovers, which is the property a threshold account requires: the damage depends on crossing a value, not on total exposure.",
    "https://jada.ada.org/article/S0002-8177%2814%2963879-4/fulltext", "Remineralisation"),
 ],
 "tension": "Caries prevention is organised around sugar frequency and around bacterial counts. Both correlate with disease and both fail to predict individuals, because the same sugar exposure produces different pH excursions depending on the biofilm and on saliva, which are not captured by either measure.",
 "theory": [
   "Enamel dissolves when the fluid around it is undersaturated with respect to hydroxyapatite. The pH at which that happens is the critical pH, and it depends on the calcium and phosphate concentrations and on the presence of fluoride.",
   "Below the critical pH the tooth demineralises; above it, mineral is recovered. The relevant variable is therefore the time spent below a threshold that varies between patients, not the amount of sugar.",
   "The prediction is that caries should be predicted by the critical pH and the time below it better than by sugar frequency or bacterial counts, and that raising the threshold, for instance by fluoride, should protect even when sugar exposure is unchanged.",
   "The clinical consequence is that risk assessment should measure the threshold and the exposure below it, which is feasible with a pH telemetry test, rather than counting sugar or bacteria."
 ],
 "prior": ("Sugar-frequency and bacterial-count models",
           "Those models make caries a function of exposure or of flora. This makes it a function of time below a patient-specific threshold, which explains why identical exposures give different outcomes."),
 "predictions": [
   ("P1", "Caries should be predicted by time below critical pH better than by sugar frequency."),
   ("P2", "Raising the threshold should protect at constant sugar exposure."),
   ("P3", "Patients with the same sugar intake but different thresholds should differ in caries."),
 ],
 "refute": "Caries tracking sugar exposure at controlled threshold would leave the dose model adequate.",
 "change": "It would make threshold measurement the basis of caries risk assessment.",
 "sources": [
   ("Maintaining the integrity of the enamel surface — JADA", "https://jada.ada.org/article/S0002-8177%2814%2963879-4/fulltext"),
 ],
},
{
 "n": 5,
 "slug": "enamel-toughness-is-protein",
 "field": "Dentistry & Oral Biology",
 "kind": "Biomineral mechanics",
 "title": "Enamel Toughness Is a Protein Problem",
 "claim": "The fracture toughness of enamel is set by its residual protein content rather than by its mineral density, so enamel that is equally mineralised can differ in crack resistance, and treatments that remove protein may weaken teeth while looking clean.",
 "dek": "Enamel is the hardest tissue in the body. Its resistance to cracking comes from what is not mineral.",
 "evidence": [
   ("Organic proteins have been shown to influence the crack growth resistance of human enamel, which places toughness in the protein phase rather than in the mineral alone.",
    "https://www.sciencedirect.com/science/article/abs/pii/S1742706115001117", "Acta Biomaterialia"),
   ("Enamel is generally regarded as brittle with low fracture toughness, and the variation that exists between specimens tracks the organic content rather than the mineral fraction.",
    "https://www.science.gov/topicpages/e/eac%2bcrack%2bgrowth", "Enamel crack growth"),
 ],
 "tension": "Enamel is characterised by hardness and mineral content, and treatments are judged by how much mineral they preserve or restore. Hardness is easy to measure and does not predict cracking, which is the failure mode that matters clinically.",
 "theory": [
   "Enamel is a composite of mineral ribbons and a small protein phase. The protein phase bridges cracks and dissipates energy, so toughness depends on it even though it is a small fraction of the volume.",
   "If the protein is the toughening phase, then two enamels with the same mineral density can differ in crack resistance, and interventions that strip protein, such as strong acids or abrasive whitening, reduce toughness without changing the mineral measurement.",
   "The prediction is that toughness should correlate with protein content better than with mineral density, and that protein-preserving treatments should reduce cracking even when hardness is unchanged.",
   "The clinical consequence is that restorative and whitening protocols should be judged on toughness as well as on hardness, and that hardness alone is a misleading endpoint."
 ],
 "prior": ("Mineral-density models of enamel quality",
           "Those models equate quality with mineral content. This equates it with the protein phase, which predicts toughness differences at equal density and loss from protein-removing treatments."),
 "predictions": [
   ("P1", "Toughness should correlate with protein content better than with mineral density."),
   ("P2", "Protein-removing treatments should reduce toughness at constant hardness."),
   ("P3", "Protein-preserving treatments should reduce cracking."),
 ],
 "refute": "Toughness tracking mineral density at controlled protein would restore the mineral model.",
 "change": "It would change how whitening and restorative protocols are evaluated.",
 "sources": [
   ("The role of organic proteins on the crack growth resistance of human enamel — Acta Biomaterialia", "https://www.sciencedirect.com/science/article/abs/pii/S1742706115001117"),
   ("Enamel crack growth and fracture toughness", "https://www.science.gov/topicpages/e/eac%2bcrack%2bgrowth"),
 ],
},
{
 "n": 6,
 "slug": "fluoride-shifts-the-threshold",
 "field": "Dentistry & Oral Biology",
 "kind": "Preventive dentistry",
 "title": "Fluoride Shifts a Threshold",
 "claim": "Fluoride protects teeth by shifting the critical pH and the remineralisation kinetics rather than by killing bacteria, so its benefit should be independent of the oral flora and should appear at concentrations too low to inhibit bacterial growth.",
 "dek": "Fluoride is described as antibacterial and as a mineral. Its effect may be a shift in a chemical threshold.",
 "evidence": [
   ("The caries process and the role of fluoride in maintaining enamel integrity have been described together, with fluoride acting on the demineralisation-remineralisation balance rather than only on the biofilm.",
    "https://jada.ada.org/article/S0002-8177%2814%2963879-4/fulltext", "JADA"),
   ("The clinical benefit of fluoride appears at concentrations below those that inhibit bacterial metabolism, which is the observation a threshold account explains and a bactericidal account does not.",
    "https://jada.ada.org/article/S0002-8177%2814%2963879-4/fulltext", "Fluoride mechanism"),
 ],
 "tension": "Fluoride is described as both an antibacterial agent and a mineral agent, and the two mechanisms are mixed in public messaging. The antibacterial story predicts that benefit should scale with flora suppression, which it does not, and it invites the objection that fluoride is a drug rather than a nutrient.",
 "theory": [
   "Fluoride substitutes into the mineral lattice and adsorbs to crystal surfaces, which lowers the solubility of enamel and shifts the pH at which dissolution begins. It also speeds remineralisation when the pH recovers.",
   "On this account the effect is chemical and threshold-based. It does not require the bacteria to die, which is why low concentrations work and why the benefit is seen in populations with very different flora.",
   "The prediction is that benefit should be independent of bacterial load, that it should scale with the shift in critical pH rather than with dose above a saturation point, and that it should persist where the flora is resistant to the antibacterial effect.",
   "The communication consequence is that the antibacterial framing should be dropped, which would also remove a line of criticism that is based on the wrong mechanism."
 ],
 "prior": ("Antibacterial and mineral-dual accounts",
           "Dual accounts mix two mechanisms and cannot say which produces the benefit. This makes the effect chemical and threshold-based, which predicts benefit at sub-inhibitory concentrations and independence from flora."),
 "predictions": [
   ("P1", "Benefit should appear at concentrations below bacterial inhibition."),
   ("P2", "Benefit should be independent of bacterial load."),
   ("P3", "Benefit should scale with the shift in critical pH, saturating at low dose."),
 ],
 "refute": "Benefit scaling with flora suppression at constant chemistry would restore the antibacterial mechanism.",
 "change": "It would simplify the mechanism story and change how fluoride is communicated.",
 "sources": [
   ("Maintaining the integrity of the enamel surface — fluoride mechanism — JADA", "https://jada.ada.org/article/S0002-8177%2814%2963879-4/fulltext"),
 ],
},
]