Single-Cell Transcriptional Profile Construction of Rat Pituitary Glands before and after Sexual Maturation and Identification of Novel Marker Spp1 in Gonadotropes.

The mammalian pituitary gland drives highly conserved physiological processes such as somatic cell growth, pubertal transformation, fertility, and metabolism by secreting a variety of hormones. Recently, single-cell transcriptomics techniques have been used in pituitary gland research. However, more studies have focused on adult pituitary gland tissues from different species or different sexes, and no research has yet resolved cellular differences in pituitary gland tissue before and after sexual maturation. Here, we identified a total of 15 cell clusters and constructed single-cell transcriptional profiles of rats before and after sexual maturation. Furthermore, focusing on the gonadotrope cluster, 106 genes were found to be differentially expressed before and after sexual maturation. It was verified that Spp1, which is specifically expressed in gonadotrope cells, could serve as a novel marker for this cell cluster and has a promotional effect on the synthesis and secretion of follicle-stimulating hormone. The results provide a new resource for further resolving the regulatory mechanism of pituitary gland development and pituitary hormone synthesis and secretion.

Evolution of optical properties and electronic structures: band gaps and critical points in MgxZn1-xO (0 ≤ x ≤ 0.2) thin films.

MgxZn1-xO (ZMO) thin films with tunable Mg content were deposited by atomic layer deposition (ALD) on silicon substrates at 190 °C. The elemental and structural properties were acquired by X-ray photoelectron spectroscopy, transmission electron microscopy, atomic force microscopy and X-ray diffraction. Spectroscopic ellipsometry measurements were performed to reveal the evolution of the dielectric functions and critical points in the ZMO thin films by point-by-point fit in the photon energy range of 1.2-6.0 eV. The dependence of the dielectric functions on doping content is clearly demonstrated and physically explained. The critical point energies and the types of interband optical transitions were extracted from standard lineshape analysis of the second derivatives of the dielectric functions. The critical point features were discussed in terms of band structure modification and structural homogeneity arisen by introducing the Mg dopant into the films. Controlling these transitions by changing the doping content will be of practical significance in emerging ZMO-based thin-film photonic and optoelectronic devices.

Bone marrow-derived mesenchymal stem cells induced by inflammatory cytokines produce angiogenetic factors and promote prostate cancer growth.

BACKGROUND: Prostate is susceptible to infection and pro-inflammatory agents in a man's whole life. Chronic inflammation might play important roles in the development and progression of prostate cancer. Mesenchymal stem cells (MSCs) are often recruited to the tumor microenvironment due to local inflammation. We have asked whether stimulation of MSCs by pro-inflammatory cytokines could promote prostate tumor growth. The current study investigated the possible involvement of MSCs stimulated by pro-inflammatory cytokines in promotion and angiogenesis of prostate cancer through relative pathway in vitro and in vivo. METHODS: A syngeneic mouse model of C57 was established. The murine prostate cancer cells (RM-1) mixing with MSCs treated with tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) or vehicle were subcutaneously injected into C57 mice. Tumor volume of C57 mouse model was estimated and serum level of platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) was test by Enzyme-linked Immunosorbent Assay (ELISA). A hen egg test-chorioallantoic membrane (HET-CAM) assay was applied to test the effect of conditioned media of stimulated MSCs in chorioallantoic membrane angiogenesis. Short interfering RNA (siRNA) knocked down either hypoxia-inducible factor-1alpha (HIF-1α) or nuclear factor-erythroid-2-related factor 2 (NRF2) were employed. mRNA of PDGF and VEGF in MSCs, as well as NRF2 and HIF-1α was test by Real time polymerase chain reaction (PCR) analyses. Protein expression levels of PDGF and VEGF from conditioned medium, NRF2, HIF-1α, as well as PDGF and VEGF in MSCs were detected by Western blot analysis. RESULTS: MSCs treated with TNF-α and IFN-γ promote tumor growth in C57 syngeneic mouse model, correlating with increased serum level of PDGF, VEGF. HET-CAM assay shows the angiogenic effect of conditioned medium of MSCs pre-treated with the pro-inflammatory cytokines. mRNA and protein levels of two pro-angiogenic factors (PDGF and VEGF) and key hypoxia regulators (HIF-1α and NRF2) in MSCs were induced after MSCs' pretreatment. siRNA knockdown either HIF-1α or NRF2 results reduction of PDGF and VEGF expression. CONCLUSIONS: MSCs stimulated by pro-inflammatory cytokines increase the expression of PDGF and VEGF via the NRF2-HIF-1α pathway and accelerate prostate cancer growth in mice.

Updated incidence rates and risk factors of esophageal cancer in Nan'ao Island, a coastal high-risk area in southern China.

Esophageal cancer (EC) is one of the most common cancers in China. The purpose of this study was to investigate the updated incidence rates and risk factors of EC in Nan'ao Island, where the EC incidence rate was chronically the highest in southern China. To calculate the annual incidence rate, data on 338 EC cases from Nan'ao Cancer Registry system diagnosed during 2005-2011 were collected. A case-control study was conducted to explore the EC risk factors. One hundred twenty-five alive EC patients diagnosed during 2005-2011 and 250 controls were enrolled into the case-control study. A pre-test questionnaire on demography, dietary factors, drinking water treatment, and behavioral factors was applied to collect information of all participants. The average EC incidence rates during 2005-2011 were 66.09/105, 94.62/105, 36.83/105 for both genders, males and females, respectively, in Nan'ao Island. The EC incidence rate in males was 2.40- to 4.55-fold higher than that in females in the period from 2006 to 2011 (P < 0.05). Considering the onset age, males tend to be much younger than females and reached peak incidence rate at a younger age (P < 0.05). Drinking water treatment by filter (odds ratio [OR] = 0.28, 95% confidence interval [95% CI] = 0.13-0.58) and fruit consumption (OR = 0.55, 95% CI = 0.32-0.94) reduced the risk for EC. On the contrary, the pickled vegetables consumption (OR = 2.64, 95% CI = 1.46-4.76) and liquor drinking (OR = 2.32, 95% CI = 1.21-4.44) increased the risk for EC. These results may be of importance for future research on EC etiology and prevention strategies.

Streptomyces tremellae sp. nov., isolated from a culture of the mushroom Tremella fuciformis.

A novel actinomycete strain, designated Js-1T, was isolated from Tremella fuciformis collected from Gutian, Fujian Province, in southeastern China. The taxonomic status of this strain was determined by a polyphasic approach, which demonstrated that the novel strain was a member of the genus Streptomyces. The cell walls of this strain were found to contain ll-diaminopimelic acid, muramic acid and glycine. An analysis of whole-cell hydrolysates revealed that no characteristic sugar was present. The key identified menaquinones were MK-9 (H6) and MK-9 (H8), while the diagnostic polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylmethylethanolamine and phosphatidylglycerol. The main cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, C16 : 0 and iso-C16 : 0. An analysis of an almost complete 16S rRNA gene sequence showed that the strain shared the highest levels of sequence similarity with Streptomyces sannanensisKC-7038T (97.87 %), Streptomyces hebeiensis YIM 001T (97.84 %), Streptomyces pathocidini NBRC 13812T (97.80 %), Streptomyces cocklensis BK168T (97.25 %), Streptomyces coerulescens NBRC 12758T (97.12 %), Streptomyces aurantiogriseus NBRC 12842T (97.06 %) and Streptomyces rimosussubsp. rimosus ATCC 10970T (97.04 %). The DNA G+C content of the genomic DNA of strain Js-1T was 70.1 mol%. Furthermore, DNA-DNA hybridization tests revealed that the relatedness values between strain Js-1T and the most closely related species ranged from 15.10 to 47.20 %. Based on its phenotypic and genotypic characteristics, strain Js-1T (=CCTCC M 2011365T=JCM 30846T) is considered to represent a novel species within the genus Streptomyces, which we classified as Streptomycestremellae sp. nov.

The thickness-dependent band gap and defect features of ultrathin ZrO2 films studied by spectroscopic ellipsometry.

The band gap and defect features of ultrathin ZrO2 films with varying thicknesses have been investigated by spectroscopic ellipsometry through the point-by-point data inversion method. The ε2-sprectra in the 3-6 eV range are extracted based on an optical model consisting of a Si substrate/effective ZrO2 film/air ambient structure where the effective ZrO2 film is a combination of interfacial layers and ZrO2. Evident widening of the band gap with a reducing size is observed when the effective ZrO2 films are below a critical thickness, somewhere between 8.80 nm and 17.13 nm. This is due to quantum-confinement and amorphous effects. Moreover, the sub-band-gap defects at interfacial layers and in bulk ZrO2 are identified and present strong thickness dependence as well. The interfacial defects at 3.26, 4.13, 4.43, and 4.77 eV mainly exist below the critical thickness and exhibit a significant suppression with increasing film thickness. The bulk defects at 4.15 eV and 4.46 eV dominate in ZrO2 films once they are over the critical thickness. The evolution of the band gap and defects is closely related to variance in the electronic structure of amorphous ZrO2. Our results may be helpful in understanding controversial problems concerning the size effect on ultrathin high-k oxide films and exploring the further miniaturization of electronic devices based on them.

[Expression and Clinical Significance of Exosome Component 4 in Newly Diagnosed Patients with Diffuse Large B-Cell Lymphoma].

OBJECTIVE: To explore the expression of Exosome Component 4（EXOSC4） in the tissues of newly diagnosed patients with diffuse large B-cell lymphoma (DLBCL) and its clinical significance. METHODS: The expression of EXOSC4 protein in the tissues of 181 newly diagnosed DLBCL patients was analyzed by immunohistochemical staining. Clinical data were collected. The correlation between EXOSC4 protein expression in the tissues of newly diagnosed DLBCL patients and clinical features were analyzed and its prognostic significance. RESULTS: The positive rate of EXOSC4 protein expression was 68.51% in the tissues of 181 newly diagnosed DLBCL patients. These patients were divided into two groups, with 44 cases in high expression group and 137 cases in low expression group. There were no significant differences in age, gender, B symptoms, serum lactate dehydrogenase (LDH) level, Eastern Cooperative Oncology Group (ECOG) score, Ann Arbor stage, extranodal disease, International Prognostic Index (IPI) score, National Comprehensive Cancer Network IPI (NCCN-IPI) score, and cell origin between the two groups (P>0.05). Cox multivariate regression analysis showed that high EXOSC4 protein expression in tissues was an independent poor prognostic factor for OS and PFS in newly diagnosed DLBCL patients (all P<0.05). K-M survival analysis showed that newly diagnosed DLBCL patients with high EXOSC4 protein expression had significantly shorter overall survival (OS) and progression free survival (PFS) than those patients with low EXOSC4 protein expression (all P<0.05). CONCLUSION: High EXOSC4 protein expression in tissues of newly diagnosed DLBCL patients is an independent poor prognostic factor for survival.

Dexmedetomidine as an adjunct to peripheral nerve blocks in pediatric patients.

BACKGROUND: Combining local anesthetics with dexmedetomidine (DEX) for nerve blocks has been tested and confirmed as an alternative technique to strengthen analgesia in adults, but the evidence supported this proposal in pediatrics was not convincing enough. Thus, we intend to conduct a meta-analysis to make an appraisal of the effects of DEX as a local anesthetic adjuvant on peripheral nerve blocks in children. METHODS: The analysis has been registered on https://www.crd.york.ac.uk/prospero/ with the registration number CRD42021254029 on June 10th, 2021. PubMed, Ovid MEDLINE, Embase and Cochrane central register were searched for the randomized controlled trials (RCTs) that are relevant to child/pain/DEX or block up to April 30, 2021. RESULTS: Eight RCTs were included for data analysis. The pooled results showed a significantly reduced number of patients who required postoperative analgesics within DEX groups [odds ratio = 0.1, 95% confidence interval (CI) 0.03-0.32, P < 0.001]. And DEX significantly prolonged the duration of analgesia of local anesthetics in the meantime [standardized mean difference (SMD) = 4.93, 95% CI 3.02-6.83, P < 0.001]. Nevertheless, adding DEX as an adjunct to local anesthetics would significantly decrease heart rate (SMD = - 0.95, 95% CI - 1.45 to - 0.45, P < 0.001) and increase sedation score (SMD = 1.6, 95% CI 0.53-2.66, P = 0.003) simultaneously. CONCLUSIONS: Adding DEX as an adjunct to peripheral nerve blocks can prolong analgesia until postoperative 8 hours in pediatric patients. However, the benefits should be weighed against the increasing risk of bradycardia and sedation in critical children.

Anti-hyperglycaemic effect of labdane diterpenes isolated from the rhizome of Amomum maximum Roxb., an edible plant in Southwest China.

Amomum maximum Roxb. rhizome is a fork medicine mainly used in South and Southeast Asia. In present study, the hypoglycaemic effects of the ethanolic extract of A. maximum rhizome were demonstrated both on α-glucosidase assay in vitro and streptozotocin (STZ)-induced postprandial hyperglycaemia in mice. Furthermore, six labdane diterpenes, amoxanthin A (1), ottensinin (2), coronarin D (3), coronarin D methyl ether (4), isocoronarin D (5), and zerumin (6), were isolated from its ethyl acetate sub-fraction with the guidance of α-glucosidase inhibitory activity. Among these compounds, 2 and 6 exhibited significant inhibitory effect on α-glucosidase, as well as on STZ-induced high postprandial blood glucose levels in mice. Additionally, molecular docking analysis revealed that 2 and 6 could firmly bind to the active sites of α-glucosidase. These results suggest that compounds 2 and 6 are the main anti-hyperglycaemic agents present in A. maximum, which may demonstrate potential beneficial effects in diabetes management.

N,N-Bis(quinolin-8-yl)-2,2'-[(1,3,4-thia-diazole-2,5-di-yl)bis-(sulfanedi-yl)]diacetamide monohydrate.

In the title compound, C(24)H(18)N(6)O(2)S(3)·H(2)O, the thia-diazole ring makes dihedral angles of 78.00 (13) and 77.27 (13)° with the quinoline ring systems. In the crystal, mol-ecules are linked into a two-dimensional network by O-H⋯O and C-H⋯O hydrogen bonds.

N,N'-Di-8-quinolyladipamide.

The complete molecule of the title compound, C(24)H(22)N(4)O(2), is generated by a crystallographic inversion centre located at the mid-point of the central C-C bond. The quinoline ring system and the hexyl chain are both essentially planar, and the dihedral angle between them is 46.30 (2)°. Intra-molecular N-H⋯N and C-H⋯O hydrogen bonds form five- and six-numbered rings, respectively. The crystal packing is stabilized by short C-H⋯O inter-actions.

[Analysis on the volatile oil of Xinhui Pericarpium Citri Reticulatae in different years by GC/MS].

OBJECTIVE: To analyze the difference of the volatile oil of Xinhui Pericarpium Citri Reticulatae in different years. METHODS: The components and contents of the volatile oil of Xinhui Pericarpium Citri Reticulatae were analyzed in different years by GC/MS. RESULTS: The components and contents of the volatile oil of Xinhui Pericarpium Citri Reticulatae changed along with the years. CONCLUSION: With the years' extension, the components of the volatile oil changed slowly during 3 years but quickly after 3 years, a few new components appeared evenly, So there's relevance between using old Xinhui Pericarpium Citri Reticulatae and its component changing.

On-table extubation in neonates undergoing anoplasty: an experience of anesthetic management on the concept of fast-tracking anesthesia: A pilot study.

Fast-track anesthesia (FTA) is difficult to achieve in neonates due to immature organ function and high rates of perioperative events. As a high-risk population, neonates require prolonged postoperative mechanical ventilation, which may lead to contradictions in cases where neonatal intensive care unit resources and ventilator facilities are limited. The choice of anesthesia strategy and anesthetic can help achieve rapid postoperative rehabilitation and save hospitalization costs. The authors describe their experience with maintaining spontaneous breathing in neonates undergoing anoplasty without opioids or muscle relaxants.This retrospective chart review included neonates who underwent anoplasty in the authors' institution. Twelve neonates who underwent the procedure with atomized 5% lidocaine topical anesthesia around the glottis, combined with sevoflurane sedation and caudal anesthesia facilitating tracheal intubation without opioid and muscle relaxant comprised the FTA group. Ten neonates who underwent the intervention with routine anesthesia techniques in the same period comprised the control group (group C).The surgical success rate in the FTA group was 91.7%. There were no severe complications related to lidocaine administered around the glottis. Extubation time was significantly shorter in the FTA group than in group C (4 [2.5, 5.2] vs 81.5 [60.6, 96.8], respectively; P < .01). The duration of stay in the surgical intensive care unit (SICU) was longer in group C than in the FTA group (2 [2.0, 2.6] vs 1 [0.9, 2.0], respectively; P = .006,). A statistically significant lower rate of extubation-cough was noted after endotracheal tube removal in the FTA group compared with group C (18% vs 90%, respectively; P < .001). There was no difference in the duration of anesthesia or hospitalization costs between the 2 groups. No neonates required re-intubation after extubation.On-table extubation via 5% atomized lidocaine topical anesthesia around the glottis for tracheal intubation combined with sevoflurane sedation and caudal anesthesia without opioid and muscle relaxant was feasible in neonates undergoing anoplasty. This reduced time to extubation, length of SICU stay and saved resources. A similar trend in cost savings was also found; nevertheless, more studies are needed to confirm these results.

New triterpenoids and PTP1B inhibitory constituents of Pseudolarix amabilis.

Six new triterpenoids, pseudolarins A-F (1-6), were isolated from the twigs of Pseudolarix amabilis, together with four known triterpenoids (7-10) and five known diterpenoids (11-15). Their structures were determined by extensive spectroscopic analysis, and the absolute configuration of 1 was assigned by single-crystal X-ray diffraction. Compound 1 is a 3,4:9,10-diseco-cycloartane triterpenoid possessing an unprecedented 5/5/7/6/5/6/5 ring system. Compounds 1, 5, 7, 9-11, and 13 showed inhibition against protein tyrosine phosphatase 1B (PTP1B) in vitro.

Real-time ultrasonic assessment of progressive proteoglycan depletion in articular cartilage.

The loss of proteoglycan (PG) is regarded as one of the early signs of osteoarthritis (OA), thus observing the progress of PG loss would be useful for the early detection of OA. In this study, high-frequency ultrasound was used to monitor and analyze the trypsin-induced progressive degeneration in articular cartilage. Full thickness cartilage-bone specimens (n = 10) prepared from normal bovine patellae were digested using 0.25% trypsin solution for different periods of time to evaluate the dynamics of the digestion process. The trypsin penetration front was observed in M-mode image, which was acquired using a nominal 50 MHz focused transducer. The transient speed of the digestion process was estimated from the image. The digestion fraction, which represents the ratio of the digestion depth to the total cartilage thickness, was estimated from ultrasound data and histology sections. With ultrasound, the digestion fraction observed in the 10 specimens ranged from 64% to 99% and was correlated to that measured by histology (R(2) > or = 0.63, p < 0.05). It was found that the digestion speed decreased nonlinearly with depth from 0.61 +/- 0.16 microm/s (mean +/- SD) in the superficial zone to 0.04 +/- 0.02 microm/s in a region located at 70% of the cartilage thickness in depth. The relationship between the digestion depth and the exposure duration in trypsin could be described using a third order polynomial function. The full thickness of digested and undigested tissues was also measured using caliper, estimated from ultrasound data and histology sections, and compared. These findings indicate that ultrasound could provide useful information about the trypsin-induced progressive PG depletion in articular cartilage. Therefore, ultrasound represents a useful tool to evaluate the dynamics of models of OA in vitro in cartilage specimens in a research environment and this would ultimately help the in vitro examination of articular cartilage for research related to model of OA from the early stages of tissue degradation.

Continuous monitoring of sonomyography, electromyography and torque generated by normal upper arm muscles during isometric contraction: sonomyography assessment for arm muscles.

The aim of this study is to demonstrate the feasibility of using the continuous signals about the thickness and pennation angle changes of muscles detected in real-time from ultrasound images, named as sonomyography (SMG), to characterize muscles under isometric contraction, along with synchronized surface electromyography (EMG) and generated torque signals. The right biceps brachii muscles of seven normal young adult subjects were tested. We observed that exponential functions could well represent the relationships between the normalized EMG root-mean-square (RMS) and the torque, the RMS and the muscle deformation SMG, and the RMS and the pennation angle SMG for the data of the contraction phase, with exponent coefficients of 0.0341 +/- 0.0148 (Mean SD), 0.0619 +/- 0.0273, and 0.0266 +/- 0.0076, respectively. In addition, the preliminary results also demonstrated linear relationships between the normalized torque and the muscle deformation as well as the pennation angle with the ratios of 9 .79 +/- 3.01 and 2.02 +/- 0.53, respectively. The overall mean R2 for the regressions was approximately 0.9 and the overall mean relative root mean square error (RRMSE) smaller than 15%. The potential values of SMG together with EMG to provide a more comprehensive assessment for the muscle functions should be further investigated with more subjects and more muscle groups.

[Identification of Pericarpium Citri Reticulatae from different years using FTIR].

The Pericarpium Citri Reticulatae from different years were analyzed and identified by Fourier Transform Infrared Spectroscopy (FTIR) and method of relative coefficience compare in this paper. The evidence indicated that the main constituent of the alcoholic extract of Pericarpium Citri Reticulatae was hesperidin, the FTIR spectra of the alcoholic extract of Pericarpium Citri Reticulatae ranged among 2 851, 1 716 and 1 516 cm(-1), and the peak had the obvious tendency to increase while the times prolonged, moreover its second derivative spectra also made corresponding changes among 1 734, 1 517 and 1 276 cm(-1). Compared to the alcoholic extract of Pericarpium Citri Reticulatae in 1 year, their relative coefficience decreased gradually when the years increased. According to the fingerprint character of the alcoholic extract of Pericarpium Citri Reticulatae, it meant that accomplished with the time extended, the hesperidin was increasing, meanwhile, some organic acid and ester were increasing too. Above all, it was proved that FTIR was a fast and simple method to identify the Pericarpium Citri Reticulatae in different years.

Male accessory breast cancer on the abdominal wall: a case report and literature review.

BACKGROUND: Accessory breast cancer is very rare, particularly in men. Male accessory breast cancer on the abdominal wall has not been documented in the scientific literature so far. We describe a case of male accessory breast cancer on the abdominal wall. CASE PRESENTATION: We describe a male patient suffering a swelling and erosive, enlarged, and hardened abdominal wall mass with pain due to abdominal wall accessory breast cancer. The patient had no obvious disease history, and the initial clinical symptom was a small mass on the abdominal wall. B-ultrasound revealed a solid subcutaneous nodule in the right abdomen with a size of ~2.8 × 2.5 × 1.5 cm. The abdominal wall tumor resection was performed with local anesthesia. Pathological testing revealed a grade II infiltrating ductal carcinoma derived from the accessory mammary gland (right abdominal wall) with neuroendocrine characteristics, showing ER (100% strong positive), PR (100% strong positive), HER-2 (-), ki67 (40% positive), Syn (+), CgA (+), and GCDFP15 (+). CONCLUSION: Nonaxillary accessory breast cancer in males is very rare, with no obvious clinical manifestations, and could be easily ignored. This disease requires great attention from clinicians.

Surface Treatment with Non-thermal Humid Argon Plasma as a Treatment for Allergic Contact Dermatitis in a Mouse Model.

Cold plasma generated at atmospheric pressure has attracted intense interest in biomedical applications, particularly as an antimicrobial treatment. Here we report the therapeutic effect of humidified cold argon plasma on allergic contact dermatitis (ACD) in a mouse model. Treatment was carried out with different gas compositions: argon gas containing small amounts of either N2, O2, or H2O. The best effect was obtained using humid plasma (H2O addition), where the ACD symptoms decreased after one or two 1-min plasma treatments. Even for severe ACD with ulcers and crust formation, the humid plasma-treated mice recovered faster than the control group. Histopathological analysis by H&E-staining showed enhanced epithelialization with formation of collagen and hair follicles in the affected skin after humid plasma exposure. The therapeutic ability of the humid argon plasma discharge was proposed to be induced by reactive oxygen species (HxOy) transported from the discharge zone, which are adhesive and accumulate on the skin surface, penetrating the subcutis to eliminate inflammation. However, in treatments using plasma with addition of oxygen or nitrogen (without water) the active gaseous species are blocked due to poor adhesion to and penetration into the dry ACD skin, with correspondingly poor treatment effects. The enhanced in vivo healing in ACD mice indicate the non-thermal humid plasma could be a potential alternative approach for therapy of ACD and other inflammatory skin diseases.

A novel method to obtain modulus image of soft tissues using ultrasound water jet indentation: a phantom study.

The alteration of tissue stiffness is generally known to be associated with pathological changes. Ultrasound indentation is one of the methods that can be used to assess the mechanical properties of the soft tissues. It uses a flat-ended ultrasound transducer to directly contact the tissue to sense tissue deformation under an applied load. This paper introduced a novel noncontact ultrasound indentation system using water jet compression. The key idea was to utilize a water jet as the indenter as well as the coupling medium for propagation of the ultrasound beam. High frequency focused ultrasound (20 MHz) was used to measure the indentation deformation at a microscopic level. It has been demonstrated that the system could effectively assess the tissue-mimic phantoms with different stiffness. Water jet coupling allows the system to conduct C-scan on soft tissues rapidly and conveniently. By applying different pressures while taking C-scan sequences, the modulus images of the phantoms could be obtained based on the applied pressure and the phantom deformation and thickness. This paper presented the preliminary results on gel phantoms. The spatial resolution, the contrast resolution of the measurements and the reproducibility of the results were also discussed.