Biology subjects

Shintani, S. A.

Publications and source records attributed to Shintani, S. A..

4 recordsLinked to original sources

bioRxiv2026

Chaotic internal dynamics coexist with a stable temporal scaffold in a mesoscale sarcomere model informed by high-resolution recordings

During hyperthermal sarcomeric oscillations (HSOs), serial sarcomeres differ in amplitude and phase. Their fast length changes can cancel in total length, while changing relative amplitudes can move the best phase arrangement. Each model node represented one sarcomere. I tested two requirements: correct amplitude-to-sarcomere pairing and timely phase adjustment. Lower normalized residuals meant better cancellation; subtracting the minimum set by the current amplitudes isolated the part that phase adjustment could remove. Correct pairing reduced the 95th percentile of this avoidable part relative to amplitude-blind or misassigned inputs in all 20 prespecified conditions. Dynamic adjustment outperformed the best of 13 fixed arrangements in all 12 conditions with target periods of at least four HSO cycles, but only 2/8 faster conditions. A ratio of target-change time to model response time almost perfectly ranked dynamic wins above fixed wins in held-out and speed-limit tests (AUC 0.976 and 0.996), although the best cutoff differed among condition families. Replaying measured amplitude histories from five sarcomeres in seven cardiomyocytes gave a median avoidable residual of 0.000802, about 1/78 of the lowest fixed-strategy median, and outperformed three fixed strategies in 7/7 cells. Returning each history to its source sarcomere gave the lowest residual among all 120 assignments in every cell. Observed phase motion favored the predicted direction relative to the circular-shift median in 5/7 cells; the prespecified cell-level test gave P=0.1094. Within this reduced model, dynamic phase balancing requires correct node-specific information and sufficient response time. The study establishes this conditional model capacity and identifies native phase dynamics as the next mechanochemical test.

biophysics↗

bioRxiv2026

Repeatable quantum-hardware execution of a fast local-topology surrogate for hyperthermal sarcomeric oscillations

Cardiac contraction depends on sarcomeres acting locally, but a beating cardiomyocyte is not a perfectly uniform lattice: neighbouring sarcomeres can rapidly rephase while the cell keeps a slower rhythm. Hyperthermal sarcomeric oscillations (HSOs), a warmed-cardiomyocyte phenomenon previously identified at the sarcomere level, provide a compact experimental case of this mesoscale coordination problem. I recast the experimentally defined five-sarcomere HSO topology as a four-qubit quantum-hardware state space: four neighbouring-pair phase relations define 16 basis states, each state is evolved with a short nearest-neighbour two-step Trotter kernel, and IBM EstimatorV2 reads out physiology-linked diagonal observables. These readouts retain the HSO meanings of pattern persistence, one-link reconfiguration, anti-phase-rich occupancy, mismatch placement, and a topology-derived synchrony proxy (Stopo). The locked control_base lane acted as a reproducible hardware anchor. Across three independent 4096-shot candidate panels it produced weighted stay 0.8395 {+/-} 0.0016, single-link fraction 0.9134 {+/-} 0.0049, anti-phase-rich occupancy 0.4517 {+/-} 0.0019, transition edge proxy 0.5437 {+/-} 0.0016, and Stopo 0.2954{+/-}0.0002. Candidate panels then used the same lane as a model-family stress test. The overmixed reference marked a high-transition boundary, with transition mass 0.3837 {+/-} 0.0313, single-link fraction 0.8248 {+/-} 0.0198, and anti-phase-rich occupancy 0.4302 {+/-} 0.0036. The edge-like representative edge_candidate_alt3 occupied an intermediate hardware regime, with transition mass 0.2781{+/-}0.0038 and anti-phase-rich occupancy 0.4447{+/-}0.0020, while preserving statewise ordering for anti-phase-rich occupancy and Stopo. A fixed-prior closed-unitary bound placed the anti-phase-rich ceiling at 0.4642, below the biological HSO reference of 0.509, indicating model headroom rather than hardware readout failure. Thus the device functions as a hardware-aware physiological testbed: HSO-like coordination is constrained local reconfiguration, whereas excessive mixing erodes one-link and anti-phase-rich readouts. Significance statementThis study starts from a concrete living-cell phenomenon rather than from an abstract small circuit. Hyperthermal sarcomeric oscillations are warmed-cardiomyocyte sarcomere dynamics in which a beat-scale rhythm persists while neighbouring sarcomeres rapidly redistribute phase. I map a five-sarcomere HSO segment to a four-qubit nearest-neighbour topology and read it out with physiology-linked observables rather than a generic circuit score. The central result is repeatable hardware execution of biologically meaningful local-state observables, and the physiological message is that HSO local grammar is constrained one-link-dominated rephasing, not maximal mixing or simple global synchrony.

biophysics↗

bioRxiv2026

A shared rephasing compass reveals structured local mismatch placement during hyperthermal sarcomeric oscillations

Neighboring sarcomeres during hyperthermal sarcomeric oscillations (HSOs) are not perfectly synchronous, yet their local nonuniformity is organized rather than random. Earlier reanalyses of the same continuous five-sarcomere recordings showed that local reconfiguration is dominated by minimal Hamming-1/one-link updates and that fast cycles can be aligned onto a shared rephasing compass whose clearest physiological translation is mismatch-pocket placement along the observed chain. Here we integrate those results with reduced-geometry analysis that asks how the same minimal update is internally distributed within the chain. Using seven living neonatal rat cardiomyocytes recorded at 500 frames/s, we converted each fast HSO cycle into one local coordination summary, extracted event-centered internal pre-to-post sarcomere-length change patterns after subtraction of the instantaneous five-sarcomere mean, and retained exact directed one-link transitions together with mismatch-pocket context. Continuous reduced-plane trajectories were geometrically complex, and total event displacement was not identical to redistribution span. Cross-cell alignment again revealed a common rephasing order, and aligned position most strongly predicted edge-biased mismatch placement. Reduced geometry added a distinct mesoscale layer: route classes formed an ordered redistribution-span axis from compact to broad internal redistribution, and even when exact one-link transition and pocket context were matched, events still separated into compact and extended redistribution profiles. Across common matched groups, the extended family showed broader span in 8 of 9 groups (median span difference +0.423; paired Wilcoxon P = 0.027). These findings support a structured-mismatch view of HSOs: the observed five-sarcomere chain reuses the same minimal local reconfiguration through more than one internal redistribution route. Significance statementCardiac contraction must transform noisy local events into a stable beat. This study shows that local nonuniformity in living cardiomyocytes is structured at more than one mesoscale level. A shared rephasing compass organizes where a mismatch pocket tends to sit along an observed five-sarcomere chain, and reduced geometry shows that the same minimal local update can still be internally packaged through more than one redistribution route. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/714639v2_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@12d255corg.highwire.dtl.DTLVardef@efbdaborg.highwire.dtl.DTLVardef@18d5224org.highwire.dtl.DTLVardef@10bc489_HPS_FORMAT_FIGEXP M_FIG Graphical abstract. An observed fast HSO window is condensed into cycle-wise local phase summaries. A topology-based circular coordinate and cross-cell alignment yield a shared rephasing compass. The clearest primary readout of that compass is mismatch-pocket placement along the observed five-sarcomere chain, whereas reduced geometry adds a secondary descriptive layer in which route packaging is ordered from compact to broad redistribution span. C_FIG

biophysics↗

bioRxiv2026

Constrained neighboring-sarcomere phase topology shapes mean HSO amplitude in living cardiomyocytes

How neighboring sarcomeres redistribute timing while a cardiomyocyte continues to beat, and whether that coordination during warming-induced hyperthermal sarcomeric oscillations (HSOs) is random or structured, remain unresolved. We reanalyzed sarcomere-length recordings from five consecutive sarcomeres in each of seven living neonatal rat cardiomyocytes and represented each valid time point by the four neighboring-pair phase relations that define a 16-state local phase network. During HSOs, the fraction of time with trackable local phase relations increased from 0.298 before warming to 0.956 (paired Wilcoxon P = 0.0156), enabling direct analysis of local reconfiguration. Successive local states were almost always connected by Hamming-1 edges, meaning that only one neighboring-pair relation changed at a time (34/35, 97.1%, before warming; 216/230, 93.9%, during HSOs). HSOs also increased occupancy of anti-phase-rich states with three or more anti-phase neighboring pairs (0.254 to 0.509, P = 0.0156). These results indicate that HSOs do not reflect unstructured local disorder but a constrained neighboring-sarcomere phase topology. As a complementary cycle-level analysis within the same HSO window, we then asked how the observed fast amplitude of the valid-sarcomere mean trace relates to local amplitude and synchrony measured from the same valid sarcomeres. For each cycle, Yvalid, the peak-to-peak HSO amplitude of the valid-sarcomere mean trace, was closely approximated by the product of mean local HSO amplitude (A) and weighted synchrony (Rw; pooled r = 0.992, normalized mean squared error = 0.015, {beta}1 = 0.948, {beta}0 {approx} 0). A simple state-derived synchrony factor computed from the local phase patterns showed a modest positive association with Rw (cell-adjusted {beta} = 0.197, P = 0.0165), providing a bridge between the binary local-state description and the continuous synchrony summary. In blocked cross-validation, the A x Rw summary was markedly more parsimonious than an additive current-state alternative (pooled normalized mean squared error 0.0138 vs 0.1006), whereas simple history terms changed error only marginally. Thus, the main result is a constrained local phase topology during HSOs, and A x Rw serves as a descriptive cycle-level summary of the mean fast signal in the same observed segment, with local amplitude and synchrony as its two components.

biophysics↗