Macrovascular blood flow and microvascular cerebrovascular reactivity are regionally coupled in adolescence.

Cerebrovascular imaging assessments are particularly challenging in adolescent cohorts, where not all modalities are appropriate, and rapid brain maturation alters hemodynamics at both macro- and microvascular scales. In a preliminary sample of healthy adolescents (n=12, 8-25 years), we investigated relationships between 4D flow MRI-derived blood velocity and blood flow in bilateral anterior, middle, and posterior cerebral arteries and BOLD cerebrovascular reactivity in associated vascular territories. As hypothesized, higher velocities in large arteries are associated with an earlier response to a vasodilatory stimulus (cerebrovascular reactivity delay) in the downstream territory. Higher blood flow through these arteries is associated with a larger BOLD response to a vasodilatory stimulus (cerebrovascular reactivity amplitude) in the associated territory. These trends are consistent in a case study of adult moyamoya disease. In our small adolescent cohort, macrovascular-microvascular relationships for velocity/delay and flow/CVR change with age, though underlying mechanisms are unclear. Our work emphasizes the need to better characterize this key stage of human brain development, when cerebrovascular hemodynamics are changing, and standard imaging methods offer limited insight into these processes. We provide important normative data for future comparisons in pathology, where combining macro- and microvascular assessments may better help us prevent, stratify, and treat cerebrovascular disease.

Whole genome sequencing of Canadian Saccharomyces cerevisiae strains isolated from spontaneous wine fermentations reveals a new Pacific West Coast Wine clade.

Vineyards in wine regions around the world are reservoirs of yeast with oenological potential. Saccharomyces cerevisiae ferments grape sugars to ethanol and generates flavor and aroma compounds in wine. Wineries place a high-value on identifying yeast native to their region to develop a region-specific wine program. Commercial wine strains are genetically very similar due to a population bottleneck and in-breeding compared to the diversity of S. cerevisiae from the wild and other industrial processes. We have isolated and microsatellite-typed hundreds of S. cerevisiae strains from spontaneous fermentations of grapes from the Okanagan Valley wine region in British Columbia, Canada. We chose 75 S. cerevisiae strains, based on our microsatellite clustering data, for whole genome sequencing using Illumina paired-end reads. Phylogenetic analysis shows that British Columbian S. cerevisiae strains cluster into 4 clades: Wine/European, Transpacific Oak, Beer 1/Mixed Origin, and a new clade that we have designated as Pacific West Coast Wine. The Pacific West Coast Wine clade has high nucleotide diversity and shares genomic characteristics with wild North American oak strains but also has gene flow from Wine/European and Ecuadorian clades. We analyzed gene copy number variations to find evidence of domestication and found that strains in the Wine/European and Pacific West Coast Wine clades have gene copy number variation reflective of adaptations to the wine-making environment. The "wine circle/Region B", a cluster of 5 genes acquired by horizontal gene transfer into the genome of commercial wine strains is also present in the majority of the British Columbian strains in the Wine/European clade but in a minority of the Pacific West Coast Wine clade strains. Previous studies have shown that S. cerevisiae strains isolated from Mediterranean Oak trees may be the living ancestors of European wine yeast strains. This study is the first to isolate S. cerevisiae strains with genetic similarity to nonvineyard North American Oak strains from spontaneous wine fermentations.

Quantitative Assessment of Regional Pulmonary Transit Times in Pulmonary Hypertension.

BACKGROUND: Pulmonary hypertension (PH) contributes to restricted flow through the pulmonary circulation characterized by elevated mean pulmonary artery pressure acquired from invasive right heart catheterization (RHC). MRI may provide a noninvasive alternative for diagnosis and characterization of PH. PURPOSE: To characterize PH via quantification of regional pulmonary transit times (rPTT). STUDY TYPE: Retrospective. POPULATION: A total of 43 patients (58% female); 24 controls (33% female). RHC-confirmed patients classified as World Health Organization (WHO) subgroups 1-4. FIELD STRENGTH/SEQUENCE: A 1.5 T/time-resolved contrast-enhanced MR Angiography (CE-MRA). ASSESSMENT: CE-MRA data volumes were combined into a 4D matrix (3D resolution + time). Contrast agent arrival time was defined as the peak in the signal-intensity curve generated for each voxel. Average arrival times within a vessel region of interest (ROI) were normalized to the main pulmonary artery ROI (t0 ) for eight regions to define rPTT for all subjects. Subgroup analysis included grouping the four arterial and four venous regions. Intraclass correlation analysis completed for reproducibility. STATISTICAL TESTS: Analysis of covariance with age as covariate. A priori Student's t-tests or Wilcoxon rank-sum test; α = 0.05. Results compared to controls unless noted. Significant without listing P value. ICC ran as two-way absolute agreement model with two observers. RESULTS: PH patients demonstrated elevated rPTT in all vascular regions; average rPTT increase in arterial and venous branches was 0.85 ± 0.15 seconds (47.7%) and 1.0 ± 0.18 seconds (16.9%), respectively. Arterial rPTT was increased for all WHO subgroups; venous regions were elevated for subgroups 2 and 4 (group 1, P = 0.86; group 3, P = 0.32). No significant rPTT differences were found between subgroups (P = 0.094-0.94). Individual vessel ICC values ranged from 0.58 to 0.97. DATA CONCLUSION: Noninvasive assessment of PH using standard-of-care time-resolved CE-MRA can detect increased rPTT in PH patients of varying phenotypes compared to controls. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 3.

Merkel cell polyomavirus small T antigen is a viral transcription activator that is essential for viral genome maintenance.

Merkel cell polyomavirus (MCV) is a small DNA tumor virus that persists in human skin and causes Merkel cell carcinoma (MCC) in immunocompromised individuals. The multi-functional protein MCV small T (sT) activates viral DNA replication by stabilizing large T (LT) and promotes cell transformation through the LT stabilization domain (LTSD). Using MCVΔsT, a mutant MCV clone that ablates sT, we investigated the role of sT in MCV genome maintenance. sT was dispensable for initiation of viral DNA replication, but essential for maintenance of the MCV genome and activation of viral early and late gene expression for progression of the viral lifecycle. Furthermore, in phenotype rescue studies, exogenous sT activated viral DNA replication and mRNA expression in MCVΔsT through the LTSD. While exogenous LT expression, which mimics LT stabilization, increased viral DNA replication, it did not activate viral mRNA expression. After cataloging transcriptional regulator proteins by proximity-based MCV sT-host protein interaction analysis, we validated LTSD-dependent sT interaction with four transcriptional regulators: Cux1, c-Jun, BRD9, and CBP. Functional studies revealed Cux1 and c-Jun as negative regulators, and CBP and BRD9 as positive regulators of MCV transcription. CBP inhibitor A-485 suppressed sT-induced viral gene activation in replicating MCVΔsT and inhibited early gene expression in MCV-integrated MCC cells. These results suggest that sT promotes viral lifecycle progression by activating mRNA expression and capsid protein production through interaction with the transcriptional regulators. This activity is essential for MCV genome maintenance, suggesting a critical role of sT in MCV persistence and MCC carcinogenesis.

Combined modality PET/MR for the detection of severe large vessel vasculitis.

BACKGROUND: Large vessel vasculitis (LVV) can be characterized based on symptom severity, and this characterization helps clinicians decide upon treatment approach. Our aim was to compare the imaging findings of combined modality positron emission tomography/magnetic resonance (PET/MR) and inflammatory markers between severe and non-severe LVV. A retrospective query was performed to identify all patients with LVV who underwent PET/MR at our institution between January 2015 and January 2021. RESULTS: Eleven patients (nine females; age 62.2 ± 16.4 years) underwent 15 PET/MR scans. Positivity was defined by findings indicative of active LVV on each modality: PET positive if vessel metabolic activity > liver metabolic activity; MR positive if wall thickening or contrast enhancement. When positive PET or positive MR findings were considered a positive scan, LVV patients with severe disease (n = 9 scans) showed a higher number of positive scans (n = 9) compared to the number of positive scans in non-severe patients (n = 3) (p < 0.05). The sensitivity and specificity for the detection of severe LVV were 1.00 and 0.50, respectively. When only the presence of both positive PET and positive MR findings were considered a positive scan, inflammatory marker levels were not significantly different between severe and non-severe LVV groups (severe: erythrocyte sedimentation rate (ESR) = 9.8 ± 10.6 mm/h; C-reactive protein (CRP) = 0.6 ± 0.4 mg/dL) (non-severe: ESR = 14.3 ± 22.4 mm/h; CRP = 0.5 ± 0.6 mg/dL). Blood- and liver-normalized maximum standardized uptake values were not significantly different between severe and non-severe patients (1.4 ± 0.3 vs 1.5 ± 0.4; 1.1 ± 0.4 vs 1.0 ± 0.3, respectively). CONCLUSIONS: Because of the differences observed, PET/MR appears to be better suited to facilitate the characterization of LVV as severe or non-severe compared to inflammatory marker measurements and quantitative measurements of metabolic activity. Qualitative assessment of PET and MR positivity by 18F-fluorodeoxyglucose PET/MR may be able to supplement clinical symptoms-based LVV classification decisions and may be helpful when clinical symptoms overlap with other disease processes.

MRA of the Supraaortic Vasculature: Comparison of Gadobutrol and Gadoterate Meglumine at 1.5 T.

BACKGROUND: Gadobutrol (GB) and gadoterate meglumine (GM) are contrast agents used for contrast-enhanced magnetic resonance angiography (CEMRA). Supraaortic vasculature (SAV) CEMRAs are used to evaluate stroke risk and neurologic symptoms. There is a need to compare the SAV CEMRA image quality obtained with GB and GM. PURPOSE: To intra-individually compare MRA images obtained with equimolar GB and GM at 1.5 T in the SAV. STUDY TYPE: Prospective, crossover. POPULATION: Twenty-eight subjects (54 ± 13 years; 17 female). FIELD STRENGTH/SEQUENCE: 1.5 T; three-dimensional (3D) gradient recalled echo. ASSESSMENT: Quantitative image quality was measured by normalized signal intensity (SIn ) [SIn  = SI blood/SD blood] and contrast ratio (CR) [CR = SI blood/SI muscle], determined by an observer (JWC) with 1 year of vascular imaging experience. Three radiologists (AS, PA, and MU) with (5, 5, and 6 years of) vascular imaging experience evaluated image quality by Likert-scale ratings (of image impression, wall conspicuity, and artifact absence). STATISTICAL TESTS: SIn and CR were compared with paired t-tests or Wilcoxon signed-rank tests and Bland-Altman plots. Qualitative ratings were compared with Wilcoxon signed-rank test. RESULTS: No significant difference in SIn was found between GB and GM. CRs with GB were significantly higher than GM at the right common carotid (6.9 ± 2.5 vs. 4.8 ± 1), left internal carotid (7.3 ± 2 vs. 4.4 ± 1.2), right internal carotid (7.7 ± 2.2 vs. 5 ± 1.1), and left vertebral (6.6 ± 2.2 vs. 4.5 ± 1.1) arteries. Bland-Altman plots showed relatively greater differences between GB and GM at higher CRs and SIn s. GM showed significantly higher artifact than GB (3.56 ± 0.52 vs. 3.36 ± 0.46) and significantly lower overall image quality (10.73 ± 1.45 vs. 11.26 ± 1.58) at the left vertebral artery. DATA CONCLUSION: At 1.5 T and equimolar demonstration, GB (0.1 mL/kg, i.e., 0.1 mmol/kg) showed higher CRs in the SAV compared to GM (0.2 mL/kg, i.e., 0.1 mmol/kg) at most vessels. Subjective image quality was not significantly different between the two agents for most vessels. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Spontaneous surface adsorption of aqueous graphene oxide by synergy with surfactants.

The spontaneous adsorption of graphene oxide (GO) sheets at the air-water interface is explored using X-ray reflectivity (XRR) measurements. As a pure aqueous dispersion, GO sheets do not spontaneously adsorb at the air-water interface due to their high negative surface potential (-60 mV) and hydrophilic functionality. However, when incorporated with surfactant molecules at optimal ratios and loadings, GO sheets can spontaneously be driven to the surface. It is hypothesised that surfactant molecules experience favourable attractive interactions with the surfaces of GO sheets, resulting in co-assembly that serves to render the sheets surface active. The GO/surfactant composites then collectively adsorb at the air-water interface, with XRR analysis suggesting an interfacial structure comprising surfactant tailgroups in air and GO/surfactant headgroups in water for a combined thickness of 30-40 Å, depending on the surfactant used. Addition of too much surfactant appears to inhibit GO surface adsorption by saturating the interface, and low loadings of GO/surfactant composites (even at optimal ratios) do not show significant adsorption indicating a partitioning effect. Lastly, surfactant chemistry is also a key factor dictating adsorption capacity of GO. The zwitterionic surfactant oleyl amidopropyl betaine causes marked increases in GO surface activity even at very low concentrations (≤0.2 mM), whereas non-ionic surfactants such as Triton X-100 and hexaethyleneglycol monododecyl ether require higher concentrations (ca. 1 mM) in order to impart spontaneous adsorption of the sheets. Anionic surfactants do not enhance GO surface activity presumably due to like-charge repulsions that prevent co-assembly. This work provides useful insight into the synergy between GO sheets and molecular amphiphiles in aqueous systems for enhancing the surface activity of GO, and can be used to inform system formulation for developing water-friendly, surface active composites based around atomically thin materials.

Transient Sox9 Expression Facilitates Resistance to Androgen-Targeted Therapy in Prostate Cancer.

PURPOSE: Patients with metastatic prostate cancer are increasingly presenting with treatment-resistant, androgen receptor-negative/low (AR-/Low) tumors, with or without neuroendocrine characteristics, in processes attributed to tumor cell plasticity. This plasticity has been modeled by Rb1/p53 knockdown/knockout and is accompanied by overexpression of the pluripotency factor, Sox2. Here, we explore the role of the developmental transcription factor Sox9 in the process of prostate cancer therapy response and tumor progression. EXPERIMENTAL DESIGN: Unique prostate cancer cell models that capture AR-/Low stem cell-like intermediates were analyzed for features of plasticity and the functional role of Sox9. Human prostate cancer xenografts and tissue microarrays were evaluated for temporal alterations in Sox9 expression. The role of NF-κB pathway activity in Sox9 overexpression was explored. RESULTS: Prostate cancer stem cell-like intermediates have reduced Rb1 and p53 protein expression and overexpress Sox2 as well as Sox9. Sox9 was required for spheroid growth, and overexpression increased invasiveness and neural features of prostate cancer cells. Sox9 was transiently upregulated in castration-induced progression of prostate cancer xenografts and was specifically overexpressed in neoadjuvant hormone therapy (NHT)-treated patient tumors. High Sox9 expression in NHT-treated patients predicts biochemical recurrence. Finally, we link Sox9 induction to NF-κB dimer activation in prostate cancer cells. CONCLUSIONS: Developmentally reprogrammed prostate cancer cell models recapitulate features of clinically advanced prostate tumors, including downregulated Rb1/p53 and overexpression of Sox2 with Sox9. Sox9 is a marker of a transitional state that identifies prostate cancer cells under the stress of therapeutic assault and facilitates progression to therapy resistance. Its expression may index the relative activity of the NF-κB pathway.

Worm-like micelles and vesicles formed by alkyl-oligo(ethylene glycol)-glycoside carbohydrate surfactants: The effect of precisely tuned amphiphilicity on aggregate packing.

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Recent work has produced a promising molecular candidate for the formation of viscoelastic worm-like micellar solutions: a tri(ethylene glycol)-linked oleyl-ß-D-glucoside surfactant (GlcC18:1) exhibited near ideal Maxwell behavior at low concentrations (2.9 wt%) without additives at room temperature. Here, fourteen surfactants have been synthesized with structural variations based around GlcC18:1. Each contain an oligo(ethylene glycol) linker of varying length (2, 3, 4, 6 EO units) between a carbohydrate head-group (glucose, galactose, mannose, maltose, lactose, cellobiose) and a cis-unsaturated alkyl tail-group (oleyl, linoleyl, erucyl). The aqueous adsorption kinetics and self-assembly of these surfactants was explored using tensiometry and small-angle neutron scattering (SANS), respectively. With SANS we observed the formation of worm-like micelles for four surfactants, and vesicles for two surfactants which exhibited behavior similar to insoluble lipids. We also observed temperature-induced micellar elongation due to dehydration of the oligo(ethylene glycol) linker, resulting in a further three surfactants forming worm-like micelles at 50 °C. Worm-like micellar fluids were further characterized using rheology to reveal two surfactants with vastly superior viscoelastic properties compared to GlcC18:1, with >2 orders of magnitude increase in viscosity and >3 orders of magnitude increase in stress relaxation time. These results provide insight into structure-function relationships for non-ionic surfactants and demonstrate a class of designed amphiphiles with a special propensity for forming viscoelastic worm-like micellar solutions at low concentrations.

Rich liquid crystal phase behavior of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants.

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Herein, we explore the phase behavior of seven novel carbohydrate-based surfactants (CBS) containing a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8-18) and cis-unsaturated (C18:1) alkyl chains. At high aqueous concentrations, these glycolipid-like surfactants transition into a variety of lyotropic liquid crystalline phases following an expected concentration phase sequence: hexagonal (H1) → bicontinuous cubic (V1) → lamellar (Lα). Using polarizing light microscopy (PLM), a binary (surfactant-water) phase diagram for each surfactant was constructed across a temperature range (25-80 °C) revealing thermotropic behavior and a broadening of liquid crystal phase regions with increasing alkyl chain length. There was also a significant difference between saturated and unsaturated alkyl chains, due to the cis-unsaturated 'statistical bend' lowering the melting point. Small-angle X-ray scattering (SAXS) measurements were performed to characterize the liquid crystal phases, identifying highly-ordered p6m,Ia3d, and Lα crystallographic space-groups with up to 7 resolved Bragg peaks, likely due to the highly anisometric nature of the TEG-linked surfactants. The phases were shown to be more numerous and exhibited greater thermal-stability compared to well-characterized alkyl glucoside surfactants lacking an oligoethylene spacer in the literature. Finally, the characteristic dimensions of each phase were determined to enable visualization of the internal microstructures, providing insight into the impact of molecular shape and the distribution of hydro-philicity/phobicity on the formation and stability of liquid crystalline mesophases.

The effects of small molecule organic additives on the self-assembly and rheology of betaine wormlike micellar fluids.

A model zwitterionic surfactant, oleyl amidopropyl betaine (OAPB), that spontaneously forms viscoelastic wormlike micelles in aqueous solution is mixed with a variety of structurally diverse organic additives. By systematically varying the nature of these additives, insight into the effects of their aromaticity and polarity on the bulk assembly and fluid behaviour of these micelles is gained by the complementary use of small-angle neutron scattering and viscosity measurements. Inclusion of non-polar additives causes the wormlike aggregates to transition into microemulsions above a critical additive concentration; the precise partitioning within the micelle is determined using contrast variation. Alternatively, polar additives do not appear to cause evolution from the wormlike structure, but instead influence the fluid rheology, with some serving to significantly increase viscosity above that of the pure surfactant solution. Addition of these molecules is accompanied by an increase in fluid viscosity when the oxygenated group of the additive is resonance stabilised or acidic. This effect is thought to be a result of surfactant-additive synergism, in which charge screening of the surfactant head-groups causes stronger attractions between molecules, increasing the scission energy of the micelles (i.e. reducing their ability to break apart and reform). Further doping of acidic additives past a critical concentration causes phase separation of the wormlike mixtures. According to ultra-small-angle neutron scattering measurements, the incorporation of all additives (polar or non-polar, aromatic or non-aromatic) results in the formation of 'branched' wormlike networks. These findings emphasise the significant impact of impurities or additives on the properties of aqueous wormlike micellar systems formed by zwitterionic surfactants, and could also inform selection of solutes for controlling fluid rheology.

Wormlike micelle formation of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants: Structure-function relationships and rheology.

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Here, seven novel carbohydrate based surfactants (CBS) have been synthesized that contain a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8-18) and unsaturated (C18:1) alkyl chains. The aqueous adsorption and self-assembly of these surfactants was explored using tensiometry and small- and ultra-small-angle neutron scattering (SANS and USANS). With SANS we observed elongation from spherical to cylindrical micelles with increasing alkyl chain length. C16 and C18 chains exhibited pronounced Krafft points, yet formed worm-like micelles as single components upon heating to 43 and 48 °C respectively. The introduction of mono-unsaturation in the form of a C18:1 chain reduced the Krafft point and gave a surfactant that produced worm-like micelles in water without additives at room temperature. We also observed micellar elongation for C12 and C14 chains at 50 °C due to dehydration of the TEG linker. The room temperature worm-like micelles were further characterized using rheo-SANS and rheology, revealing the C18:1 surfactant to exhibit near ideal Maxwell behavior at low concentrations (2.9 wt.%). These results provide insight into structure-function relationships for CBS, and demonstrate a promising molecular candidate for the formation of viscoelastic worm-like micellar solutions.

Non-canonical activation of hedgehog in prostate cancer cells mediated by the interaction of transcriptionally active androgen receptor proteins with Gli3.

Hedgehog (Hh) is an oncogenic signaling pathway that regulates the activity of Gli transcription factors. Canonical Hh is a Smoothened- (Smo-) driven process that alters the post-translational processing of Gli2/Gli3 proteins. Though evidence supports a role for Gli action in prostate cancer (PCa) cell growth and progression, there is little indication that Smo is involved. Here we describe a non-canonical means for activation of Gli transcription in PCa cells mediated by the binding of transcriptionally-active androgen receptors (ARs) to Gli3. Androgens stimulated reporter expression from a Gli-dependent promoter in a variety of AR + PCa cells and this activity was suppressed by an anti-androgen, Enz, or by AR knockdown. Androgens also upregulated expression of endogenous Gli-dependent genes. This activity was associated with increased intranuclear binding of Gli3 to AR that was antagonized by Enz. Fine mapping of the AR binding domain on Gli2 showed that AR recognizes the Gli protein processing domain (PPD) in the C-terminus. Mutations in the arginine-/serine repeat elements of the Gli2 PPD involved in phosphorylation and ubiquitinylation blocked the binding to AR. ß-TrCP, a ubiquitin ligase that recognizes the Gli PPD, competed with AR for binding to this site. AR binding to Gli3 suppressed its proteolytic processing to the Gli3 repressor form (Gli3R) whereas AR knockdown increased Gli3R. Both full-length and truncated ARs were able to activate Gli transcription. Finally, we found that an ARbinding decoy polypeptide derived from the Gli2 C-terminus can compete with Gli3 for binding to AR. Exogenous overexpression of this decoy suppressed Gli transcriptional activity in PCa cells. Collectively, this work identifies a novel pathway for non-canonical activation of Hh signaling in PCa cells and identifies a means for interference that may have clinical relevance for PCa patients.

Self-Assembly of Long-Chain Betaine Surfactants: Effect of Tailgroup Structure on Wormlike Micelle Formation.

Long-chain amidopropyl betaines are known for their ability to self-assemble into viscoelastic wormlike micellar structures. Here, we explore the effect of tailgroup molecular architecture on this process, comparing five molecules, each with C18 chains but different levels of unsaturation and branching. The surfactants are synthesized from stearic, oleic, linoleic, linolenic, and isostearic acids. The self-assembly of these molecules in aqueous solutions is explored using small- and ultra-small-angle neutron scattering (SANS and USANS). It is seen that optimum wormlike micelle formation is achieved for the oleic-chained surfactant, and the alignment of self-assembled structures is further explored using rheo-SANS. The more highly unsaturated molecules form rodlike micelles, whereas the stearic-tailed molecule shows a pronounced Krafft point and the isostearic-chained surfactant is entirely water-insoluble. These results demonstrate the critical importance of tailgroup geometry on surfactant properties and self-assembly for this industrially important class of surfactants.

Influence of hydration and starch digestion on the transient rheology of an aqueous suspension of comminuted potato snack food.

Oral processing of most foods is inherently destructive: solids are broken into particles before reassembly into a hydrated bolus while salivary enzymes degrade food components. In order to investigate the underlying physics driving changes during oral processing, we capture the transient rheological behaviour of a simulated potato chip bolus during hydration by a buffer with or without α-amylase. In the absence of amylase and for all oil contents and solids weight fractions tested, we find a collapse of the transient data when graphed according to simple Fickian diffusion. In the presence of amylase, we find effects on the transient and pseudo steady state bolus rheology. Within the first minute of mixing, the amylase degrades only ≈6% of the starch but that leads to an order of magnitude reduction in the bolus elasticity, as compared to the case without amylase. Thus, for an in vitro bolus, only a small amount of starch needs to be digested to have a large impact on the bolus rheology very soon after mixing.