Skip to content

Gut-Lumen Uricase Physiological Regime — Computational Audit (comp-044)

Question

Does comp-019's conclusion that 5–50 mg/day oral uricase is always in a substrate-limited, flat-dose regime survive when the omitted substrate-occupancy term and a finite active window are applied using the inherited corpus priors?

Verdict

Mechanistic Extrapolation (deterministic consistency audit; inherited inputs): LEGACY UNCONDITIONAL FLAT-DOSE CLASSIFICATION NOT ROBUST TO THE TESTED DIAGNOSTICS; biological gut-sink hypothesis remains OPEN. The prior flat-dose and predicted-ΔSUA results should not guide dose or yield decisions. In the prespecified terminal-ileal clinical-cohort diagnostic, applying 0.59 µM urate, Km 25 µM, and a three-hour window moves all three tested ratios below one before any oxygen, access, or survival penalty. This establishes only that comp-019's unconditional classification was not robust to the tested substrate-occupancy and finite-window diagnostics. It does not identify the true physiological regime, reverse the old conclusion, or establish a sufficient oral dose.

Method summary

comp-044 converts UOX dose and specific activity into an upper-bound urate-degradation capacity, then explicitly applies:

  • Michaelis–Menten substrate occupancy;
  • finite active-window duration;
  • nonmechanistic scenario multipliers for pH/activity, effective oxygen-dependent activity, substrate access, and enzyme survival;
  • the legacy 233 mg/day intestinal-flux denominator, retained only to make the regime comparison legible.

Five named scenarios and a discrete 1,620-cell full-factorial grid per dose are evaluated. Grid occupancy is not treated as probability. No serum-urate change is computed.

The 8.3 U/mg specific activity, Km range, 2–4 hour active-window range, and 233 mg/day denominator are inherited or derived corpus priors. They were not newly primary-source verified for quantitative planning in comp-044. The 0.59 µM input is inherited from a grep-verified extraction of terminal-ileal fluid measurements in a balloon-enteroscopy cohort (Miyazaki et al. 2025, PMCID PMC11877951); it is not a healthy-population baseline. These inputs are adequate for the bounded internal-consistency test, not for selecting a dose.

Key results

Scenario 5 mg 25 mg 50 mg
Legacy 24-hour Vmax 32.3377 161.6886 323.3773
Terminal-ileal clinical-cohort prior: 0.59 µM, Km 25 µM, three hours; no additional penalty 0.0932 0.4660 0.9320
Same prior, with microoxic/access/survival scenario multipliers 0.0035 0.0175 0.0349
50 µM sensitivity case with the same multipliers 0.1011 0.5053 1.0106

Only the ratio-one boundary has direct mass-balance meaning. The other descriptive bins in the artifact are scanning aids. A ratio above one still does not prove complete luminal capture because local replenishment, depletion, diffusion, and reabsorption remain unmodeled.

Terms omitted from the legacy calculation

  1. Substrate occupancy: Under the inherited central inputs, 0.59 µM urate is below the 25 µM Km prior, so applying label Vmax directly overstates modeled capacity.
  2. Time exposure: The prior calculation granted every delivered milligram 24 hours at full activity; comp-044 instead tests the inherited 2–4 hour active-window range.

Oxygen, topology, access, and survival add further uncertainty but were not needed to show that the unconditional flat-dose classification was not robust to the tested diagnostics.

Limitations

  • The fixed-concentration screen is not a dynamic compartmental gut model.
  • The daily-flux denominator and local terminal-ileal clinical-cohort concentration are different kinds of quantities; their comparison is a bounded diagnostic, not physiological closure.
  • The pH, oxygen, access, and survival multipliers are scenario variables and may be correlated.
  • The 50 and 500 µM cases are sensitivity values, not measured human baselines.
  • No renal compensation, intestinal reabsorption, microbial metabolism, genotype-specific supply, or serum-pool dynamics are modeled.
  • The 8.3 U/mg activity, Km range, active-window range, and daily-flux denominator require direct primary-source verification before any quantitative planning use.

Impact on experimental priorities

Oral-UOX dose response remains a feasibility gate. Yield optimization cannot be deprioritized on comp-019's basis, and no current production figure establishes dose sufficiency. Exact configurations must first be built and characterized in the relevant construct-supply work (validation §§1.1, 1.2, and 1.5) or supplied as an exact external configuration. §1.33 then measures local urate, oxygen, configuration-specific activity, peroxide, and persistence. A topology may be nominated only within a controlled host comparison; cross-host results remain configuration-specific. §1.36 safety precedes animal escalation.

Cross-references