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Purpose To verify the hypothesis that extracellular volume fraction (ECV) and precontrast CT density are the main determinants of washout of hepatocellular carcinoma (HCC) at the equilibrium phase CT. Materials and methods Between 2018 and 2020, patients with surgically resected HCC were recruited who had undergone preoperative 4-phase CT. Those larger than 6 cm were excluded to minimize the possibility of intratumoral hemorrhage or degeneration. Two radiologists reviewed the whole images in consensus and divided cases into washout positive and negative groups. Washout positive group at the equilibrium phase was defined as “HCC showing relatively low density as compared to the surrounding background liver (BGL), irrespective of the presence of early enhancement or fibrous capsule”. Several clinico-pathological and radiological features, including ECV and precontrast CT density, were correlated to the presence of washout, using uni- and multi-variable analyses. Results 27 HCC in 24 patients met the inclusion criteria. 22 (82%) and five HCC belonged to washout positive and negative groups, respectively. Univariable analysis revealed ECV of HCC and BGL, ECV difference between HCC and BGL, and presence of fibrous capsule on the equilibrium phase CT were the significant factors. Multivariable analysis showed ECV of HCC and BGL, and precontrast CT density of BGL, were the independently significant factors related to washout, suggesting washout is more likely observed with lower HCC ECV, higher BGL ECV, and higher BGL precontrast CT density. Conclusion Major determinants of washout of HCC may be ECV of HCC and BGL, and precontrast CT density of BGL.

With age, senescence-associated (SA) CD4+ T cells that are refractory to T cell receptor (TCR) stimulation are increased along with spontaneous germinal center (Spt-GC) development prone to autoantibody production. We demonstrate that CD153 and its receptor CD30 are expressed in SA-T and Spt-GC B cells, respectively, and deficiency of either CD153 or CD30 results in the compromised increase of both cell types. CD153 engagement on SA-T cells upon TCR stimulation causes association of CD153 with the TCR/CD3 complex and restores TCR signaling, whereas CD30 engagement on GC B cells induces their expansion. Administration of an anti-CD153 antibody blocking the interaction with CD30 suppresses the increase in both SA-T and Spt-GC B cells with age and ameliorates lupus in lupus-prone mice. These results suggest that the molecular interaction of CD153 and CD30 plays a central role in the reciprocal activation of SA-T and Spt-GC B cells, leading to immunosenescent phenotypes and autoimmunity., 老化T細胞が自己免疫病や慢性炎症疾患を引き起こすメカニズムを解明 --老化関連疾患克服への新しいアプローチ--. 京都大学プレスリリース. 2022-09-22.

[Purpose] To determine the effects of lower limb ergometer exercise on the spasticity and joint range of motion of the lower extremity and gait function in patients with cerebral palsy and spastic paralysis. [Participants and Methods] This study included 8 participants with cerebral palsy and spastic paralysis (GMFCS levels I to IV) who received care at the outpatient clinic. After a 5-min rest, the lower limb ergometer exercises were performed for 10 min. We measured the participants’ arterial blood pressure, pulse rate, passive range of knee joint extension, muscle tone using the Modified Ashworth scale (MAS) and Modified Tardieu scale (MTS), and 10-m walk test (10MWT). Measurements were collected three times (at baseline before exercise, immediately at the end of exercise, and 5 min after exercise during recovery). [Results] The 10-min lower limb ergometer exercise significantly improved the knee joint extension, MAS and MTS scores, and reduced lower extremity spasticity. Furthermore, it significantly increased the range of knee joint extension and decreased the 10MWT score. [Conclusion] The results showed that the 10-minute lower limb ergometer exercise is beneficial in reducing the spasticity of the lower limb muscles and in increasing the range of motion of knee extension in paraplegic patients with cerebral palsy, suggesting that its implementation in young children could prevent spasticity and enhance motor function.

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DiHS/DRESS) is a potentially fatal multiorgan inflammatory disease associated with herpesvirus reactivation and subsequent onset of autoimmune diseases1-4. Pathophysiology remains elusive and therapeutic options are limited. Cases refractory to corticosteroid therapy pose a clinical challenge1,5 and approximately 30% of patients with DiHS/DRESS develop complications, including infections and inflammatory and autoimmune diseases1,2,5. Progress in single-cell RNA sequencing (scRNA-seq) provides an opportunity to dissect human disease pathophysiology at unprecedented resolutions6, particularly in diseases lacking animal models, such as DiHS/DRESS. We performed scRNA-seq on skin and blood from a patient with refractory DiHS/DRESS, identifying the JAK-STAT signaling pathway as a potential target. We further showed that central memory CD4+ T cells were enriched with DNA from human herpesvirus 6b. Intervention via tofacitinib enabled disease control and tapering of other immunosuppressive agents. Tofacitinib, as well as antiviral agents, suppressed culprit-induced T cell proliferation in vitro, further supporting the roles of the JAK-STAT pathway and herpesviruses in mediating the adverse drug reaction. Thus, scRNA-seq analyses guided successful therapeutic intervention in the patient with refractory DiHS/DRESS. scRNA-seq may improve our understanding of complicated human disease pathophysiology and provide an alternative approach in personalized medicine.

Conventional dendritic cells (cDCs) derive from bone marrow (BM) precursors that undergo cascades of developmental programs to terminally differentiate in peripheral tissues. Pre-cDC1s and pre-cDC2s commit in the BM to each differentiate into CD8α + /CD103 + cDC1s and CD11b + cDC2s, respectively. Although both cDCs rely on the cytokine FLT3L during development, mechanisms that ensure cDC accessibility to FLT3L have yet to be elucidated. Here, we generated mice that lacked a disintegrin and metalloproteinase (ADAM) 10 in DCs ( Itgax -cre × Adam10 -fl/fl; ADAM10 ∆DC ) and found that ADAM10 deletion markedly impacted splenic cDC2 development. Pre-cDC2s accumulated in the spleen with transcriptomic alterations that reflected their inability to differentiate and exhibited abrupt failure to survive as terminally differentiated cDC2s. Induced ADAM10 ablation also led to the reduction of terminally differentiated cDC2s, and restoration of Notch signaling, a major pathway downstream of ADAM10, only modestly rescued them. ADAM10 ∆DC BM failed to generate cDC2s in BM chimeric mice with or without cotransferred ADAM10-sufficient BM, indicating that cDC2 development required cell-autonomous ADAM10. We determined cDC2s to be sources of soluble FLT3L, as supported by decreased serum FLT3L concentration and the retention of membrane-bound FLT3L on cDC2 surfaces in ADAM10 ∆DC mice, and by demonstrating the release of soluble FLT3L by cDC2 in ex vivo culture supernatants. Through in vitro studies utilizing murine embryonic fibroblasts, we determined FLT3L to be a substrate for ADAM10. These data collectively reveal cDC2s as FLT3L sources and highlight a cell-autonomous mechanism that may enhance FLT3L accessibility for cDC2 development and survival.

論叢(Article), 坂本恵子:塾講師, 元高校教員

Hair follicles (HFs) function as hubs for stem cells, immune cells, and commensal microbes, which must be tightly regulated during homeostasis and transient inflammation. Here we found that transmembrane endopeptidase ADAM10 expression in upper HFs was crucial for regulating the skin microbiota and protecting HFs and their stem cell niche from inflammatory destruction. Ablation of the ADAM10-Notch signaling axis impaired the innate epithelial barrier and enabled Corynebacterium species to predominate the microbiome. Dysbiosis triggered group 2 innate lymphoid cell-mediated inflammation in an interleukin-7 (IL-7) receptor-, S1P receptor 1-, and CCR6-dependent manner, leading to pyroptotic cell death of HFs and irreversible alopecia. Double-stranded RNA-induced ablation models indicated that the ADAM10-Notch signaling axis bolsters epithelial innate immunity by promoting β-defensin-6 expression downstream of type I interferon responses. Thus, ADAM10-Notch signaling axis-mediated regulation of host-microbial symbiosis crucially protects HFs from inflammatory destruction, which has implications for strategies to sustain tissue integrity during chronic inflammation.

Macrophages (MΦ) play a vital role in tissue homeostasis, but their functions in skin hypodermis, a common site of Staphylococcus aureus (S. aureus) infection, remains largely unexplored. Using flow-cytometry, bulk RNA-seq and single-cell RNA-seq, two MΦ subsets with distinct transcriptomes were uncovered. Both MΦ subsets relied on colony stimulating factor 1 (CSF1) receptor signaling for their survival. Single-cell RNA-seq of non-immune cells identified fibroblasts (FB) as a major source of dermal and hypodermal CSF1. Analysis of dermal and hypodermal stromal cells transcriptomes revealed Tek (encoding Tie2) in hypodermal FB as a potential driver for skin layer-specific ablation of CSF1. Tek-cre x Csf1-floxed mice (Csf1ΔTek) displayed a striking post-natal ablation of hypodermal MΦ associated with an alteration of the collagen network and increased accumulation of hyaluronic acid (HA). Generation of a ligand-receptor map identified candidate genes involved in hypodermal MΦ-FB crosstalk. Among which, depletion of insulin-like growth factor 1 (IGF1) from MΦ in Csf1r-cre x Igf1-floxed (Igf1ΔCsf1r) recapitulated the alteration of the ECM observed in absence of hypodermal MΦ. Interestingly, upon injecting S. aureus into the hypodermis, Csf1ΔTek and Igf1ΔCsf1r mice displayed striking reduction of the cellulitis phenotype as compared to WT mice. Pre-injection of HA attenuated cellulitis in WT mice, suggesting that deposition of HA in the absence of MΦ or MΦ-derived IGF1 conferred host protection against S. aureus. Thus, while hypodermal MΦ critically maintained ECM homeostasis, this provided a niche for S. aureus infection, highlighting implications for novel therapeutic strategies in S. aureus soft-tissue infections.

A 70-year-old woman has been followed up for chronic hepatitis C and hepatocellular carcinoma which had been successfully controlled by several sessions of radiofrequency ablation. A small cystic lesion in segment IV associated with adjacent intrahepatic duct dilatation was firstly noted 4 years before on MR imaging, which showed gradual increase in size and significant interval change in the MRI signal intensity of the cystic content on the follow-up examinations. The mass finally reached 4 cm in its largest dimension, associated with slightly enhancing thickened wall, suggesting its neoplastic nature. The mass was surgically resected and a final diagnosis of mucinous cystic neoplasm (MCN) of the liver was made. MCN is usually considered to have no communication with intrahepatic duct, but in this particular case, the communication with the biliary duct was suggested from its early stage of the lesion, which would be the cause of peculiar chronological change in MR appearance.

Purpose To clarify clinico-radiological factors for high-risk esophago-gastric varices (EGV), including extracellular volume fraction (ECV) of the liver, pancreas, and the spleen. Methods Between 2014 and 2018, 70 chronic liver disease patients who underwent 4-phase CT of the upper abdomen and either of upper gastrointestinal tract endoscopy, or actual treatment for bleeding EGV, within three months after CT, were retrospectively included. Patients were subdivided into high-risk EGV group (HRG), who had high-risk endoscopic findings or actual hemostatic treatments, and non-high-risk EGV group (NHRG). ECV of the liver, pancreas, and the spleen was measured on the ECV map generated from routine diagnostic CT data, and additional clinico-radiological factors including direct visualization of EGV on portal venous phase CT, were correlated to HRG, using both univariable and multivariable analyses. Results There were 8 and 62 patients in HRG, and NHRG, respectively. None had symptoms related to EGV at the time of CT examinations. Univariable analysis revealed splenic volume, liver and splenic ECVs, and EGV visualization on portal venous phase CT, as significant factors. Multivariable analysis suggested that EGV visualization, splenic ECV, and splenic volume were independently significant factors. Using these three factors, sensitivity/specificity/positive predictive value/negative predictive value/accuracy = 100/85/40/100/87% were obtained with partition model analysis. Conclusions High-risk EGV can be predicted with acceptable accuracy using routine diagnostic CT data including splenic ECV.

Ultrasonography in a 60-year-old man with chronic hepatitis C (CHC) demonstrated multiple hyperechoic nodules. Radiological investigations did not reveal any signs of malignancy. However, magnetic resonance chemical shift imaging showed multiple focal fatty changes in the liver. Urinary levels of uroporphyrin and coproporphyrin were elevated, and we made a diagnosis of porphyria cutanea tarda. Direct-acting antivirals, ledipasvir/sofosbuvir, were initiated for CHC, which led to sustained viral response, resolution of the liver nodules, and normalization of urinary porphyrin. Hepatitis C virus infection can cause porphyria cutanea tarda with multiple hyperechoic liver nodules, which might be cured by direct-acting antivirals.

To assess whether extracellular volume fraction (ECV) calculated from iodine(-blood) density images (I-B) of dual-energy liver CT (DECT) equilibrium phase data (EqD) is useful in estimating the degree of liver fibrosis. Consecutive 52 patients with chronic liver disease who underwent fast kV switching DECT and liver MR elastography (MRE) were retrospectively enrolled. Iodine(-water) density images (I-W) and I-B generated from EqD and ECV were calculated. As blood pools, abdominal aorta (Ao) and suprahepatic inferior vena cava (IVC) were chosen, and, therefore, 4 types of ECV (ECVI-W Ao, ECVI-W IVC, ECVI-B Ao, ECVI-B IVC) were obtained. ECV was also calculated using conventional method (ECVconv Ao). The correlation coefficients (R2 or rho) of these five ECVs versus liver stiffness (MRE) or pathologically proven fibrosis grades were compared. As for correlation with liver stiffness, R2 for ECVconv.Ao, ECVI-W Ao, ECVI-B Ao, ECVI-W IVC, and ECVI-B IVC, were 0.26, 0.34, 0.44, 0.39, and 0.52, respectively (all p

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DiHS/DRESS) is a potentially fatal multiorgan inflammatory disease associated with herpesvirus reactivation and subsequent onset of autoimmune diseases

A 61-year-old man with chronic hepatitis B and a history of alcohol overconsumption was admitted to our hospital for the scrutiny of multiple echogenic liver nodules. CT and hepatobiliary phase of gadoxetate-enhanced MR imaging revealed no nodular lesions. Quantitative fat fraction images and R2* map of MR imaging suggested homogeneous steatosis and uneven iron deposition in the liver, namely moderately and severely elevated R2* values at the nodules and surrounding background liver, respectively. Biopsy specimens showed macrovesicular fatty liver and less iron deposition at the echogenic nodules, and microvesicular fatty change and more prominent iron deposition at the surrounding liver tissue. The patient's urinary uroporphyrin level was elevated, and the final diagnosis of porphyria cutanea tarda was made. In patients with history of excessive alcohol intake or viral hepatitis, echogenic nodules on ultrasonography along with radiological evidence of absence of space occupying lesions, and presence of excessive intrahepatic fat and iron, might suggest a possible diagnosis of porphyria cutanea tarda.

Purpose: To elucidate whether any differences are present in the stiffness map obtained with a multiscale direct inversion algorithm (MSDI) vs that with a multimodel direct inversion algorithm (MMDI), both qualitatively and quantitatively. Materials and Methods: The MR elastography (MRE) data of 37 consecutive patients who underwent liver MR elastography between September and October 2014 were retrospectively analyzed by using both MSDI and MMDI. Two radiologists qualitatively assessed the stiffness maps for the image quality in consensus, and the measured liver stiffness and measurable areas were quantitatively compared between MSDI and MMDI. Results: MMDI provided a stiffness map of better image quality, with comparable or slightly less artifacts. Measurable areas by MMDI (43.7 ± 17.8 cm2) was larger than that by MSDI (37.5 ± 14.7 cm2) (P < 0.05). Liver stiffness measured by MMDI (4.51 ± 2.32 kPa) was slightly (7%), but significantly less than that by MSDI (4.86 ± 2.44 kPa) (P < 0.05). Conclusion: MMDI can provide stiffness map of better image quality, and slightly lower stiffness values as compared to MSDI at 3T MRE, which radiologists should be aware of.

To clarify the details of homogeneously enhancing lesions on contrast-enhanced ultrasonography (CEUS) and also to elucidate whether their differential diagnosis is possible. Seventy-three homogeneously enhancing lesions on CEUS were retrospectively selected. Two radiologists first assessed conventional US findings alone in consensus to differentiate malignant vs. benign lesions. Then, qualitative and quantitative CEUS findings were analyzed to determine the useful findings for the differential diagnosis. Determined CEUS findings were applied to the indeterminate lesions based on conventional US findings to see whether CEUS can improve the diagnostic performance. There were 42 cancers (58 %) out of 73. Sensitivity and specificity using conventional US findings alone were 91 and 55 %, respectively. Among the CEUS findings tested, multivariate analysis revealed only the type 3 enhancement pattern, which indicates a larger enhancing area than the precontrast hypoechoic lesion, was related to malignancy (p

Objectives To assess whether extracellular volume fraction (ECV) obtained from routine liver CT equilibrium phase data utilizing new subtraction algorithm is useful in estimating the degree of liver fibrosis. Materials and methods Consecutive 41 patients, 21 men and 20 women, with chronic liver diseases who underwent quadri-phase liver CT and MR elastography within 3 months were retrospectively enrolled. Subtraction image of unenhanced from equilibrium phase (240 s) images using conventional and new algorithms were made. We firstly assessed the quality of these subtraction algorithms using patients in whom anatomical misregistration between the two image sets were prominent. Then, ECVs were calculated using both subtraction data sets (ECV-convSub, and ECV-newSub, respectively). ECV were also calculated by traditional manual method (ECV-man). Correlation coefficients of 3 types of ECV were compared using liver stiffness (kPa) as measured by MR elastography and pathologically proven fibrosis grades as reference standards. Results For eleven patients with prominent anatomical misregistration between the unenhanced and equilibrium phases, new algorithm provided significantly better subtraction images than the conventional one (p = 0.001, Wilcoxon’s signed rank test). As for correlation with liver stiffness, R2 for ECV-man, ECV-convSub, and ECV-newSub, were 0.57, 0.59, and 0.66, respectively (all p Conclusion ECV-newSub showed better correlation to liver stiffness and pathological fibrosis grades than ECV-convSub and ECV-man, which could be a reliable biomarker of liver fibrosis obtained from routine clinical diagnostic imaging data, where equilibrium phase delay time was set at 240 s.

The purpose of this study was to measure the aerodynamic force acting upon a soccer ball spun in a wind-tunnel test. In particular, we prepared two types of spinning soccer balls (air and motor types), measured the aerodynamic force on each, and examined the validity of the measurement method. In the case of the air-type spinning ball, the ball was made to spin by applying compressed air from an air compressor via an air duster. In the case of the motor-type spinning ball, a motor was placed at the middle inside the ball, and the ball was then automatically spun. First, both the air- and motor-type spinning balls demonstrated very strong spin-parameter ( Sp ) dependence with respect to drag during spinning. In addition, the side-force coefficient showed signs of linear increase as Sp increased in the motor-type spinning ball, whereas it increased along a slight curve in the air-type spinning ball. In particular, a negative Magnus effect was observed in the motor-type spinning ball when the Reynolds number was approximately 2.0 × 10 5 and Sp was approximately 0.14 (-0.007) and when the Reynolds number was approximately 2.2 × 10 5 and Sp was approximately 0.13 (-0.005).

PURPOSE We retrospectively evaluated the incidence and related factors of obliteration of the lower bile duct after oral administration of contrast medium (OCM) probably resulting from its regurgitation into the biliary system (OCMRB) as observed on images of MR cholangiopancreatography (MRCP). METHODS We retrospectively analyzed 305 MRCP images in 278 patients obtained between February 2010 and March 2011 using negative OCM with 1.0- and 1.5-tesla clinical units. OCMRB was defined as positive when visualization of the common bile duct was clear on precontrast 2-dimensional (2D) MRCP but obliterated on postcontrast 3-dimensional (3D) MRCP. Two abdominal radiologists reviewed all images in consensus. The incidence of OCMRB was correlated to various clinicoradiological factors. RESULTS We observed OCMRB on 11 MRCP images in 10 patients (3.6%). Among various clinicoradiological factors, the presence of juxtapapillary diverticula, pneumobilia, and history of intervention to the papilla were suggested as significant factors related to positive OCMRB with multivariate analysis (P < 0.05). CONCLUSION OCMRB occurs in about 4% of the patients who undergo MRCP, typically in those with juxtapapillary diverticula, pneumobilia, and history of papillary intervention. Acquisition of MRCP images before OCM may secure visualization of the common bile duct in these patients.

Immune cells and epithelium form sophisticated barrier systems in symbiotic relationships with microbiota. Evidence suggests that immune cells can sense microbes through intact barriers, but regulation of microbial commensalism remain largely unexplored. Here, we uncovered spatial compartmentalization of skin-resident innate lymphoid cells (ILCs) and modulation of sebaceous glands by a subset of RORγt(+) ILCs residing within hair follicles in close proximity to sebaceous glands. Their persistence in skin required IL-7 and thymic stromal lymphopoietin, and localization was dependent on the chemokine receptor CCR6. ILC subsets expressed TNF receptor ligands, which limited sebocyte growth by repressing Notch signaling pathway. Consequently, loss of ILCs resulted in sebaceous hyperplasia with increased production of antimicrobial lipids and restricted commensalism of Gram-positive bacterial communities. Thus, epithelia-derived signals maintain skin-resident ILCs that regulate microbial commensalism through sebaceous gland-mediated tuning of the barrier surface, highlighting an immune-epithelia circuitry that facilitates host-microbe symbiosis.

The purpose of this study was to clarify the fundamental mechanism of a goalkeeper's (GK) diving motion according to the height and distance of the shot. We performed an experiment in which 11 university GKs participated. Their average height was 178.4cm (SD = 6.2), and average mass was 71.2kg (SD = 2.5). They were asked to dive toward and touch balls set at three different heights (2.2 m from the ground, 1.22 m from the ground, and safety mat height) located a short or a long distance (1.83 m and 3.50 m, respectively) from the GK. Kinematics and kinetic data were recorded using a three-dimensional motion analysis system (VICON; Oxford Metrix, 250frames/s) and two force platforms (9281A, Kistler Inc. 9287B, Kistler Inc., 1000Hz). By examining the GKs’ diving motions, we calculated the position of center of gravity (CG), joint angle, ground reaction force (GRF) and joint torque. The results indicated that the magnitude of the GRF under both legs and the direction of the GRF under the ball-side (BS) leg differed with the ball height. We also found that a higher dive by the GKs corresponded to a larger counter-movement of the contralateral-side (CS) leg and more exertion of extension torques at the hip and foot for take-off compared to those in lower dives (p < .05). Furthermore, there were differences in timing of extension of the BS leg.These findings suggest that during the take-off part of the diving motion of a GK, depending on the ball height the CS leg controls the magnitude of power and the BS leg controls both the magnitude and the direction of power in order for the GK to dive directly towards the ball.

A comparative study of the ball-kicking motion for the instep kick of female and male athletes was conducted by using an optical motion capture system. The results showed that the thigh and shank energies were lower overall for female athletes, and that the average thigh-to-shank energy ratio was significantly lower for female athletes than for male athletes (p < 0.05). This suggests that female athletes may have poorer thigh-to-shank energy transfer techniques than do male athletes. Furthermore, a forward dynamics simulation was performed to examine the impact of the vertical force component of the hip joint on the swing velocity. As the vertical translational force increased during a forward swing, the swing velocity also tended to increase. Therefore, accelerating the hip joint of the kicking leg in the vertical direction during the forward swing of the instep motion may be assumed to increase the swing velocity. Such hip acceleration is one of the technical elements that could be improved to increase ball velocity in female athletes.

Typically, soccer balls are constructed with 32 pentagonal and hexagonal panels. More recently Teamgeist and Jabulani balls have 14 and 8 panels, respectively, with dramatically different panel shapes and designs from conventional balls. The latest model called Cafusa, made with 32 panels, has been adopted by many soccer leagues. However, there are few studies on the aerodynamic characteristics of these balls. This study examined the trajectory and aerodynamic characteristics of soccer balls constructed with different numbers and shapes of panels. Results of wind tunnel tests indicated that the aerodynamic forces varied significantly according to the number of panels. They were also substantially different by the panel orientation of the balls and their rotation. The results for points of impact showed that the ball trajectory changes dramatically according to panel orientation, suggesting that panel orientation has significant effects on the flight of the balls. Furthermore, the panel shapes, rather than the numbers, are considered to affect the flight trajectory because balls with the same number of panels varied depending on their panel shape and orientation.

Soccer balls differing in surface material and number of panels were analysed, and a kick-robot equipped with a dynamometer was used to measure the impulsive force at the time of impact. Cafusa had the smallest maximum impulsive force, whereas Jabulani had a larger impulse than all other balls at each tested speed. These results presumably relate to the flexibility of the surface material and structural characteristics of each ball. One reason why Jabulani has the highest impulse may be that the machine-stitched composition of its inner layer is stiffer than the strips of cloth stuck together in Cafusa.