[Effects of pelvic-abdominal mechanics exercises during pregnancy on improving perinatal pelvic floor function in primiparous women].

Objective: To explore the effects of pelvic-abdominal mechanics exercises during pregnancy on improving pelvic floor function in primiparous women during the perinatal period. Methods: A single-center prospective study selected 200 primipara of singleton pregnancies with prenatal care and delivery established at Shanghai Tongren hospital from June 2022 to June 2023 as the study subjects. Participants were divided into two groups: the exercise group (100 cases) and the control group (100 cases) by using a random number table method, five participants dropped out of the study due to reasons such as follow-up failure. Ultimately, the exercise group consisted of 97 cases, while the control group consisted of 98 cases. Participants who engaged in pelvic-abdominal mechanics exercises for at least 3 months, exercising once a week, were included in the exercise group. Those who did not engage in exercise were included in control group. Comparing the two groups in terms of pregnancy discomfort symptoms, delivery outcomes, postpartum pelvic floor electromyography results, postpartum quality of life, and pelvic floor disease incidence. The statistical methods utilized included independent t-test, Pearson chi-square test, Fisher's exact test, and Mann-Whitney U test. Results: In the late stage of pregnancy, the VAS score for low back pain was 5.05±1.22 in the exercise group and 5.47±1.55 in the control group, with a statistically significant difference (t=2.090, P<0.05). The PFDI-20 score was 23.33±8.41 in the exercise group and 25.76±8.34 in the control group, with a statistically significant difference (t=2.026, P<0.05). The PFIQ-7 score was 19.21±7.69 in the exercise group and 26.66±6.19 in the control group, with a statistically significant difference (t=6.851, P<0.05). There was no statistically significant difference in sleep quality and incidence of urinary incontinence between the two groups in late pregnancy (t=1.252, P=0.396, P>0.05). In terms of childbirth outcomes, the exercise group had a vaginal delivery rate of 81.44% (79 cases), while the control group had a rate of 64.28% (63 cases), with a statistically significant difference (χ2=9.022, P<0.05). The duration of the second stage of labor was (42.68±21.38) minutes in the exercise group and (50.54±21.33) minutes in the control group, with a statistically significant difference (t=2.178, P<0.05). At 42 days postpartum, the evaluation of pelvic floor function showed that the vaginal pressure in the exercise group was 62.19±10.04, while in the control group it was 52.68±15.55, with a statistically significant difference (t=-5.074, P<0.05). The MOS grading in the exercise group was 3.82±1.26, whereas in the control group it was 2.34±1.55, with a statistically significant difference (t=-7.355, P<0.05). In terms of the incidence of postpartum pelvic floor disorders, the occurrence of pelvic organ prolapse was 7.22% in the exercise group and 12.24% in the control group, with no statistically significant difference (χ2=1.402, P>0.05). The occurrence rate of stress urinary incontinence was 13.4% in the exercise group and 30.61% in the control group, with a statistically significant difference (P=0.015, P<0.05). Conclusion: Pelvic-abdominal mechanics exercises may have some advantages in reducing symptoms related to perinatal pelvic floor dysfunction, enhancing pelvic floor function, and preventing the occurrence of pelvic floor disease.

Comparison of transcriptome profiles of nucleated red blood cells in cord blood between preterm and full-term neonates.

BACKGROUND: The reactivation of fetal γ-globin expression is an effective strategy for ameliorating the clinical symptoms of ß-hemoglobinopathies. However, the mechanism of globin switching, especially the roles of long non-coding RNAs (lncRNAs) in this process, remains elusive. METHODS: We compared the in vivo transcriptome profiles of nucleated red blood cells (NRBCs) isolated from the umbilical cord blood of preterm and full-term newborns. We collected 75 umbilical cord blood samples and performed qPCR of the candidate genes. RESULTS: In this study, we identified 7,166 differentially expressed protein-coding genes, 3,243 differentially expressed lncRNAs, and 79 differentially expressed microRNAs. Our data show that the Fanconi anemia pathway and the H19/let-7/LIN28B axis may be involved in γ- to ß-globin gene switching. Moreover, we constructed the hub gene network of the differentially expressed transcription factors. Based on qPCR, we found that BCL11A was differentially expressed based on biological sex. We also confirmed that H19 is differentially expressed and established the H19-related network to reveal the potential regulatory mechanisms. CONCLUSION: We present the profiles of the in vivo transcriptome differences of NRBCs between preterm and full-term neonates for the first time, and provide novel research targets for ß-hemoglobinopathies.

Elevated expression of CDT1 in childhood acute lymphoblastic leukemia promotes cell proliferation, invasion and migration through activation of EMT.

Acute lymphoblastic leukemia (ALL) is a malignant disease of the hematopoietic system. At present, the mechanism and pathogenesis of ALL have not been fully clarified. This study aimed to illustrate the roles of Cdc10 protein-dependent transcript 1 (CDT1) in ALL. Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) was performed to examine serum levels of CDT1 in childhood ALL patients and healthy volunteers. The interaction between CDT1 expression and prognosis of childhood ALL was analyzed. Meanwhile, expressions of CDT1 in ALL cell lines were determined. Furthermore, CDT1 knockdown model was constructed in ALL cells, and Cell Counting Kit-8 (CCK-8), and Transwell assays were conducted to analyze the effect of CDT1 on the biological functions of ALL cells. Potential mechanism was further explored through detecting the expressions of Epithelial-to-mesenchymal transition (EMT)-related genes. RT-qPCR results indicated that serum level of CDT1 in childhood ALL patients was remarkably higher than that of healthy volunteers. Childhood ALL patients with high expression of CDT1 had lower overall survival rate compared with those expressing low expression of CDT1. CDT1 knockdown remarkably decreased the proliferation and metastasis abilities of pediatric ALL cells. Results of western blot showed that CDT1 might contribute to the malignant progression of childhood ALL via activating EMT. The findings showed that elevated CDT1 facilitated ALL metastasis by promoting EMT, suggesting that CDT1 played a pivotal role in ALL metastasis and may serve as a novel prognostic biomarker and therapeutic target.

Serotypes and Hemagglutinin Gene Sequences of Avibacterium paragallinarum Isolated in Taiwan.

Despite routine vaccine use, sporadic outbreaks of infectious coryza in poultry continue to occur in Taiwan. This study was designed to determine the serotypes and the complete nucleotide sequences of a hemagglutinin gene (HMTp210) of Avibacterium paragallinarum isolated in Taiwan between 1994 and 2017. Hemagglutination inhibition tests showed that these isolates belong to serogroups B and C. Sequence analyses of the HMTp210 gene showed that Taiwanese serogroup B isolates are most similar (94.7%-98.2% identity) to strain FARPER-174 isolated in Peru in 2015. In contrast, Taiwanese serogroup C isolates are most similar (96.3%-99.8% identity) to strain H-18 isolated in Japan in 1976. This is the first report showing the presence of A. paragallinarum of serogroup B in Taiwan. In addition, one Taiwanese isolate showed cross-reactivity with serogroup B and C antisera. This isolate contains a chimeric HMTp210 gene that might result from recombination between serogroups B and C. These findings could be valuable for the epidemiologic study and molecular serotyping of A. paragallinarum.

Serotipos y secuencias de genes de hemaglutinina de Avibacterium paragallinarum aislados en Taiwán. A pesar del uso rutinario de vacunas, en Taiwán continúan ocurriendo brotes esporádicos de coriza infecciosa en avicultura. Este estudio fue diseñado para determinar los serotipos y las secuencias de nucleótidos completas de un gene de hemaglutinina (HMTp210) de Avibacterium paragallinarum aislado en Taiwán entre 1994 y 2017. Las pruebas de inhibición de la hemaglutinación mostraron que estos aislamientos pertenecen a los serogrupos B y C. El análisis de secuencias del gene HMTp210 mostró que los aislamientos del serogrupo B taiwaneses son más similares (94.7% ­98.2% de identidad) a la cepa FARPER-174 aislada en Perú en el año 2015. En contraste, los aislamientos del serogrupo C taiwaneses son más similares (96.3% ­99.8% de identidad) a la cepa H -18 aislada en Japón en 1976. Este es el primer reporte que muestra la presencia de A. paragallinarum del serogrupo B en Taiwán. Además, un aislado taiwanés mostró reactividad cruzada con los antisueros del serogrupo B y C. Este aislado contiene un gene HMTp210 quimérico que podría resultar de la recombinación entre los serogrupos B y C. Estos hallazgos podrían ser valiosos para el estudio epidemiológico y la serotipificación molecular de A. paragallinarum.

Positive-Parity Linear-Chain Molecular Band in

An inelastic excitation and cluster-decay experiment ^{2}H(^{16}C,^{4}He+^{12}Be or ^{6}He+^{10}Be)^{2}H was carried out to investigate the linear-chain clustering structure in neutron-rich ^{16}C. For the first time, decay paths from the ^{16}C resonances to various states of the final nuclei were determined, thanks to the well-resolved Q-value spectra obtained from the threefold coincident measurement. The close-threshold resonance at 16.5 MeV is assigned as the J^{π}=0^{+} band head of the predicted positive-parity linear-chain molecular band with (3/2_{π}^{-})^{2}(1/2_{σ}^{-})^{2} configuration, according to the associated angular correlation and decay analysis. Other members of this band were found at 17.3, 19.4, and 21.6 MeV based on their selective decay properties, being consistent with the theoretical predictions. Another intriguing high-lying state was observed at 27.2 MeV which decays almost exclusively to ^{6}He+^{10}Be(∼6 MeV) final channel, corresponding well to another predicted linear-chain structure with the pure σ-bond configuration.

Relationship of Peripheral Lymphocyte Subsets and Skeletal Muscle Mass Index in Sarcopenia: A Cross-Sectional Study.

OBJECTIVES: Lymphocytes can affect the proliferation and migration of muscle satellite cells, which may be associated with reduced muscle mass in patients with sarcopenia. The present study aimed to further enrich understandings of the changes of blood lymphocytes and explore the relationship between peripheral lymphocyte subsets and muscle mass in patients with sarcopenia. DESIGN: A cross-sectional study. SETTING: Geriatrics department of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. METHODS: Eighty-five subjects were enrolled in this study, and were divided into two groups: the sarcopenia group (n=60) and the non-sarcopenia group (n=25). The diagnosis of sarcopenia was based on the diagnostic criteria updated by the Asian Working Group for Sarcopenia (AWGS) in 2014. Complete blood count, peripheral lymphocyte subsets, and body composition of all patients were measured. RESULTS: Skeletal muscle mass index (SMI) was negatively correlated with CD4+CD28null T lymphocytes in peripheral blood in patients with sarcopenia. CONCLUSION: The result of our study may point out the role of CD4+CD28null T lymphocytes in the pathogenesis of sarcopenia.

Polaronic effect in the x-ray absorption spectra of La1-x Ca x MnO3 manganites.

X-ray absorption spectroscopy (XAS) is performed to study changes in the electronic structures of colossal magnetoresistance (CMR) and charged ordered (CO) La1-x Ca x MnO3 manganites with respect to temperature. The pre-edge features in O and Mn K-edge XAS spectra, which are highly sensitive to the local distortion of MnO6 octahedral, exhibit contrasting temperature dependence between CMR and CO samples. The seemingly counter-intuitive XAS temperature dependence can be reconciled in the context of polarons. These results help identify the most relevant orbital states associated with polarons and highlight the crucial role played by polarons in understanding the electronic structures of manganites.

Metaraminol use during spinal anaesthesia for caesarean section: a meta-analysis of randomised controlled trials.

INTRODUCTION: During caesarean section, the use of a vasopressor is often required to achieve haemodynamic stability of the parturient. Metaraminol is a vasopressor used in this context in some countries. However, the differences between metaraminol and other vasopressors remain unclear. METHODS: A search of the PubMed, Cochrane Library, and Embase databases was performed to identify randomised controlled trials comparing the use of metaraminol with other vasopressors during spinal anaesthesia at caesarean section. The selected studies were subjected to meta-analysis and risk-of-bias assessment. RESULTS: Four randomised, controlled trials met the selection criteria and 409 parturients who underwent an elective caesarean section were included in this meta-analysis. The quality of these trials was good. Metaraminol was associated with higher umbilical arterial pH (standardised mean difference [SMD] 0.82, 95% CI 0.01 to 1.62, P=0.05); a lower incidence of fetal acidosis (RR 0.08, 95% CI 0.01 to 0.63, P=0.02); and a lower incidence of nausea or vomiting (RR 0.16, 95% CI 0.04 to 0.57, P=0.0005) than was ephedrine. Metaraminol resulted in higher umbilical arterial pH (SMD 0.42, 95% CI 0.15 to 0.68, P=0.002) but a higher incidence of reactive hypertension (RR 1.80, 95% CI 1.32 to 2.46, P=0.0002) than did phenylephrine. CONCLUSION: The results of this study showed that for spinal anaesthesia at elective caesarean section, metaraminol may be a more suitable vasopressor than ephedrine and its effects are at least not inferior to those of phenylephrine.

[The genetic factors of non-response to anti-vascular endothelial growth factor therapy].

The response to anti-vascular endothelial growth factor (VEGF) treatment is variable. It is generally measured in terms of changes in correlated functional and/or anatomical outcomes, and patients are then classified as optimal response, poor response and non-response. The precise cause of non-response remains undetermined. A variety of factors could account for poor or non-response to anti-VEGF therapy, such as age, baseline vision, disease course, lesion characteristics and genomic polymorphism. At the present time, many studies on the genetic factors of non-response or poor response to anti-VEGF treatment mainly focus on VEGF genes (VEGF-A, VEGFR-2), complement factor H (CFH), age-related maculopathy susceptibility 2 (LOC387715/ARMS2), high temperature factor A-1 (HTRA1), interleukin-related gene (IL-8 rs4073) and so forth. It is still worthy of further investigations that how to assess genetic reasons for non-response or poor response, so that we can provide individualized treatment sequences and predict the response to anti-VEGF therapy. (Chin J Ophthalmol, 2018, 54:873-878).

Syncope caused by complete heart block and ventricular arrhythmia as early manifestation of systemic lupus erythematosus in a pregnant patient: a case report.

Systemic lupus erythematosus (SLE) can affect all heart structures including the conduction system, with either reversible or permanent derangement. However, only a few cases of adult SLE and complete atrioventricular (AV) block have been reported. We describe a young pregnant woman who initially presented with complete AV block on electrocardiography before the diagnosis of SLE. Syncope subsequently developed during the postpartum period due to frequent nonsustained polymorphic ventricular tachycardia, suggesting lupus myocarditis. The ventricular arrhythmia was successfully treated by intravenous corticosteroids, lidocaine and implantation of a permanent pacemaker. This may represent the first report of complete AV block with polymorphic ventricular tachycardia, which was identified before the other clinical features of SLE fully manifested. SLE should be considered if a patient presents with complete AV block without other clinical features. It may warn for early diagnosis and appropriate treatment of SLE including lupus-related heart disease.

[Reproductive health status of female workers in a railway system and possible influencing factors].

Objective: To investigate the reproductive health status of female workers in a railway system and possible influencing factors. Methods: From January to June, 2016, a cross-sectional epidemiological investigation was performed to collect 2 165 female workers aged 17-55 years. A women's health questionnaire was used to collect the data on their occupation and health, and their reproductive health status was analyzed. Results: The female workers exposed to occupational hazards had significantly higher incidence rates of gynecological diseases, abnormal menstruation, and infertility than those not exposed to such hazards (χ(2)=32.29, 12.42, and 4.23, respectively, all P<0.05) . There were significant differences in the incidence rates of gynecological diseases, abnormal menstruation, adverse pregnancy outcomes, and pregnancy complications between the female workers with different working forms and states (χ(2)=17.19, 23.03, 200.65, and 21.28, respectively, all P<0.05) . There were significant differences in the incidence rates of gynecological diseases, abnormal menstruation, and pregnancy complications between the female workers with different behavioral habits (χ(2)=15.65, 36.23, and 25.35, respectively, all P<0.05) . The logistic regression analysis showed that exposure to occupational hazards, married state, medium-grade professional title or above, work in shifts, sitting for a long time, standing for a long time, and video operation were risk factors for gynecological diseases, and the prevalence rate of gynecological diseases increased with age. Exposure to occupational hazards, night shifts, staying up late, and sitting for a long time were risk factors for abnormal menstruation. Exposure to occupational hazards was a risk factor for infertility. Medium-grade professional title or above was a risk factor for adverse pregnancy outcomes. Married state, medium-grade professional title or above, standing for a long time, and high mobility in job form and state were risk factors for pregnancy complications. Conclusion: Exposure to occupational hazards, job form and state, and unhealthy behavioral habits may affect reproductive health status in female workers in the railway system.

Nonlinear Ultrafast Spin Scattering in the Skyrmion Phase of Cu_{2}OSeO_{3}.

Ultrafast x-ray scattering studies of the topological Skyrmion phase in Cu_{2}OSeO_{3} show the dynamics to be strongly dependent on the excitation energy and fluence. At high photon energies, where the electron-spin scattering cross section is relatively high, the excitation of the topological Skyrmion phase shows a nonlinear dependence on the excitation fluence, in contrast to the excitation of the conical phase which is linearly dependent on the excitation fluence. The excitation of the Skyrmion order parameter is nonlinear in the magnetic excitation resulting from scattering during electron-hole recombination, indicating different dominant scattering processes in the conical and Skyrmion phases.

ARHGEF10 knockout inhibits platelet aggregation and protects mice from thrombus formation.

Essentials ARHGEF10 single-nucleotide polymorphism provides risk of ischemic and atherothrombotic stroke. The role of ARHGEF10 in platelet function was examined using ARHGEF10 knockout mice. ARHGEF10 deficiency inhibits platelet function and arterial thrombus formation. ARHGEF10 knockout protects mice from stroke-induced infarction. SUMMARY: Background ARHGEF10, a member of the Rho guanine nucleotide exchange factor (GEF) family, stimulates Rho GTPases. Rho GTPases have been reported to regulate a variety of cellular behaviors, such as cell polarity, cytoskeletal organization, and gene transcription. ARHGEF10 single-nucleotide polymorphisms are linked to the risk of ischemic stroke. However, the role of ARHGEF10 in platelet function remains unknown. Objective To examine the role of ARHGEF10 in platelet function. Methods ARHGEF10-/- were generated. We examined the in vitro and in vivo effects of ARHGEF10 knockout on platelet function and arterial thrombosis formation. Results ARHGEF10-/- mice had normal platelet counts, but showed altered aggregation in response to thrombin, collagen, ADP, protease-activated receptor-4 peptide, and U46619 stimulation. ARHGEF10 knockout influenced platelet spreading on fibrinogen-coated surfaces, and caused the platelets to show less lamellipodia-like extension than wild-type platelets. ARHGEF10 knockout also inhibited platelet clot retraction induced by thrombin stimulation. ARHGEF10 knockout resulted in prolonged tail bleeding time and inhibited the stable thrombus formation induced by FeCl3 in the carotid artery. Conclusions ARHGEF10 serves as an important regulator in platelet shape change, spreading, and aggregation. Moreover, ARHGEF10 also plays an important role in arterial thrombosis formation.

Graphene Q-switched distributed feedback fiber lasers with narrow linewidth approaching the transform limit.

A compact all-in-line graphene-based distributed feedback Bragg-grating fiber laser (GDFB-FL) with narrow linewidth of hundreds kHz is demonstrated and investigated in this study. Performing as an optical saturable absorber, graphene oscillates the initially kHz linewidth DFB-FL, and generates high-quality passively Q-switched pulses. Pumped with a 980 nm continuous-wave laser, the Q-switched GDFB-FL observes ~1 µs pulse durations, with pulse energies up to ~10 nJ and approaching the transform limit. The peak power is ~600 times higher than the original DFB-FL laser. By optimizing the cavity design and the graphene material, it is predicted that fast Q-switched pulses with more than MHz repetition rates and sub-100 ns pulse durations are achievable. Such transform-limited Q-switched GDFB-FLs with narrow linewidth of sub-MHz have long coherence length, good tunability, stability, compactness and robustness, with potential impact in optical coherent communications, metrology and sensing.

[Study of survival factors of oral squamous cell carcinoma].

Objective: To explore the survival factors for oral squamous cell carcinoma(OSCC). Methods: A total of 492 patients with OSCC were recruited from the First Affiliated Hospital of Fujian Medical University from June 2003 to December 2014. Then, 456 cases were included in the present study according to inclusion and exclusion criteria. Clinical and follow-up data were collected to evaluate survival factors of OSCC. Survival rates were calculated using the Kaplan-Meier method and compared using the Log-rank test. The Cox proportional hazards regression model was used to estimate the hazard ratio(HR)and 95% confidence intervals(CI)of survival factors. We also stratified by TNM Classification of Malignant Tumours stage and BMI to assess the association between treatments and OSCC outcomes. Results: The age of the recruited patients was(57.89±11.61)years, and the proportions in TNM stages Ⅰ, Ⅱ, Ⅲ, and Ⅳ were 14.0%(64), 23.7%(108), 16.1%(73)and 42.5%(194), respectively. The multivariate Cox regression indicated that the HR(95% CI)of the increase to mortality risk associated with stage T2-T3, T4(T1 as reference), stage N2-N3(N0 as reference), poormoderate differentiation, BMI<18.5 kg/m2(compared with BMI 18.5-23.9 kg/m2), alcohol consumption ≥20 g/d(compared with no alcohol)before treatment were 2.69(1.21-5.95), 3.40(1.54-7.53), 2.65(1.17-6.00), 2.56(1.39-4.71), 2.00(1.15-3.50), 2.09(1.11-3.93), and 1.68(1.03-2.73), respectively. The stratification analysis demonstrated that, compared with surgery alone, surgery combined with radiotherapy reduced the mortality risk of stage Ⅲ-Ⅳ, HR(95% CI)0.33(0.12-0.93). Surgery combined with chemoradiotherapy reduced the mortality risk of OSCC with normal BMI, HR(95% CI)were 0.39(0.17-0.87). Conclusions: Clinical stage and histological grade are survival factors for patients with OSCC.

Smooth and flat phase-locked Kerr frequency comb generation by higher order mode suppression.

High-Q microresonator is perceived as a promising platform for optical frequency comb generation, via dissipative soliton formation. In order to achieve a higher quality factor and obtain the necessary anomalous dispersion, multi-mode waveguides were previously implemented in Si3N4 microresonators. However, coupling between different transverse mode families in multi-mode waveguides results in periodic disruption of dispersion and quality factor, and consequently causes perturbation to dissipative soliton formation and amplitude modulation to the corresponding spectrum. Careful choice of pump wavelength to avoid the mode crossing region is thus critical in conventional Si3N4 microresonators. Here, we report a novel design of Si3N4 microresonator in which single-mode operation, high quality factor, and anomalous dispersion are attained simultaneously. The novel microresonator is consisted of uniform single-mode waveguides in the semi-circle region, to eliminate bending induced mode coupling, and adiabatically tapered waveguides in the straight region, to avoid excitation of higher order modes. The intrinsic quality factor of the microresonator reaches 1.36 × 10(6) while the group velocity dispersion remains to be anomalous at -50 fs(2)/mm. With this novel microresonator, we demonstrate that broadband phase-locked Kerr frequency combs with flat and smooth spectra can be generated by pumping at any resonances in the optical C-band.

Selective interlayer ferromagnetic coupling between the Cu spins in YBa2Cu3O7-x grown on top of La0.7Ca0.3MnO3.

Studies to date on ferromagnet/d-wave superconductor heterostructures focus mainly on the effects at or near the interfaces while the response of bulk properties to heterostructuring is overlooked. Here we use resonant soft x-ray scattering spectroscopy to reveal a novel c-axis ferromagnetic coupling between the in-plane Cu spins in YBa2Cu3O7-x (YBCO) superconductor when it is grown on top of ferromagnetic La0.7Ca0.3MnO3 (LCMO) manganite layer. This coupling, present in both normal and superconducting states of YBCO, is sensitive to the interfacial termination such that it is only observed in bilayers with MnO2 but not with La0.7Ca0.3O interfacial termination. Such contrasting behaviors, we propose, are due to distinct energetic of CuO chain and CuO2 plane at the La0.7Ca0.3O and MnO2 terminated interfaces respectively, therefore influencing the transfer of spin-polarized electrons from manganite to cuprate differently. Our findings suggest that the superconducting/ferromagnetic bilayers with proper interfacial engineering can be good candidates for searching the theorized Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state in cuprates and studying the competing quantum orders in highly correlated electron systems.

A low-phase-noise 18 GHz Kerr frequency microcomb phase-locked over 65 THz.

Laser frequency combs are coherent light sources that simultaneously provide pristine frequency spacings for precision metrology and the fundamental basis for ultrafast and attosecond sciences. Recently, nonlinear parametric conversion in high-Q microresonators has been suggested as an alternative platform for optical frequency combs, though almost all in 100 GHz frequencies or more. Here we report a low-phase-noise on-chip Kerr frequency comb with mode spacing compatible with high-speed silicon optoelectronics. The waveguide cross-section of the silicon nitride spiral resonator is designed to possess small and flattened group velocity dispersion, so that the Kerr frequency comb contains a record-high number of 3,600 phase-locked comb lines. We study the single-sideband phase noise as well as the long-term frequency stability and report the lowest phase noise floor achieved to date with -130 dBc/Hz at 1 MHz offset for the 18 GHz Kerr comb oscillator, along with feedback stabilization to achieve frequency Allan deviations of 7 × 10(-11) in 1 s. The reported system is a promising compact platform for achieving self-referenced Kerr frequency combs and also for high-capacity coherent communication architectures.