Evaluation of fetal cardiac function in fetal growth restriction via fetal HQ analysis based on two-dimensional STI.

BACKGROUND: Abnormalities of the fetal cardiovascular system caused by fetal growth restriction (FGR) may lead to adverse outcomes. The fetal cardiac function assessment is of great significance for treatment selection and prognostic evaluation of fetuses with FGR. OBJECTIVE: This study aimed to explore the value of fetal HQ analysis based on speckle tracking imaging (STI) to evaluate the global and regional cardiac function of fetuses with early-onset or late-onset FGR. METHODS: From June 2020 to November 2022, 30 pregnant women with early-onset FGR (21-38 gestational weeks) and 30 pregnant women with late-onset FGR (21-38 gestational weeks) in the Department of Ultrasound, Shandong Maternal and Child Health Hospital were enrolled. Also, 60 healthy volunteer pregnant women were enrolled as two control groups according to the principle of matching gestational weeks (21-38 gestational weeks). The fetal cardiac functions, including fetal cardiac global spherical index (GSI), left ventricular ejection fraction (LVEF), fractional area change (FAC) of both ventricles, global longitudinal strain (GLS) of both ventricles, 24-segmental fractional shortening (FS), 24-segmental end-diastolic ventricular diameter (EDD), and 24-segmental spherical index (SI), were assessed using fetal HQ. The standard biological values of fetuses and Doppler blood flow parameters of fetuses and mothers were measured. The estimated fetal weight (EFW) measured by the last prenatal ultrasound was calculated, and the weights of newborns were followed up. RESULTS: Among early FGR, late FGR and total control group, significant differences were found in global cardiac indexes of right ventricle (RV), left ventricle (LV) and GSI. For the segmental cardiac indexes, there are significant differences in three groups except parameter of LVSI. Compared with the control group at the same gestational week, the Doppler indexes including MCAPI and CPR in both the early-onset FGR group and the late-onset FGR group were significantly different. The intra- and inter-observer correlation coefficients of RV FAC, LV FAC, RV GLS, and LV GLS were good. Further, the intra- and inter-observer variability in FAC and GLS was small, as analyzed using the Bland-Altman scatter plot. CONCLUSIONS: Fetal HQ software based on STI showed that FGR affected the global and segmental cardiac function of both ventricles. FGR no matter early-onset or late-onset altered Doppler indexes significantly. The FAC and the GLS had satisfactory repeatability in evaluating fetal cardiac function.

Intraoperative dexmedetomidine-related polyuria: A case report and review of the literature.

Dexmedetomidine-related polyuria has been observed in animal experimental studies, while only limited cases have been reported in humans. Thus, this rare effect is not well recognized. Herein, we report the case of a 26-year-old man who underwent total thyroidectomy and experienced intraoperative dexmedetomidine-related polyuria, which was subsequently resolved using pituitrin. Moreover, we review the current literature on dexmedetomidine-related polyuria and analyze the potential mechanisms of this rare effect.

New Phenylpropanoid Glycosides from Illicium majus and Their Radical Scavenging Activities.

Chemical investigation of the ethanol extract of the branch and leaves of Illicium majus resulted in the isolation of four new phenylpropanoid glycosides (1-4) and one new phenolic glycoside (9), along with 13 known ones. Spectroscopic techniques were used to elucidate the structures of the new isolates such as 3-[(2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-2,3-dihydro-1-benzofuran-5-yl]propyl ß-D-glucopyranoside (1), [(2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-2,3-dihydro-1-benzofuran-3-yl]methyl 2-O-α-L-rhamnopyranosyl-ß-D-glucopyranoside (2), [(2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-2,3-dihydro-1-benzofuran-3-yl]methyl 2-O-α-L-rhamnopyranosyl-ß-D-xylopyranoside (3), 3-[(2R,3S)-3-({[2-O-(4-O-acetyl-α-L-rhamnopyranosyl)-ß-D-xylopyranosyl]oxy}methyl)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-2,3-dihydro-1-benzofuran-5-yl]propyl acetate (4), and 4-(2-hydroxyethyl)phenyl 3-O-ß-D-glucopyranosyl-ß-D-glucopyranoside (9). Free radical scavenging activities of the isolates were elucidated through the DPPH assay method. The most active compounds, 1-O-caffeoyl-ß-D-glucopyranose (17) and soulieana acid 1 (18), exhibited moderate radical scavenging activities (IC50 =37.7±4.4 µM and IC50 =97.2±3.4 µM, respectively). The antibacterial activities of the isolates against Staphylococcus aureus and Escherichia coli were also assessed, and no activity was shown at the measured concentration (<32 µg/mL).

[Impact of high temperature on sperm function: An update].

Spermatogenesis and sperm maturation are closely related to temperature and require a temperature slightly lower than the normal body temperature. Therefore, high temperature is an important external factor affecting sperm function, and the studies on the underlying mechanisms are of great significance for the treatment of male infertility, improvement of in vitro sperm preservation and further elucidation of spermatogenesis and sperm maturation. It is known currently that the influence of high temperature on sperm involves genetic material, morphology, survival rate, motility and fertility, most of which have been found in various species and may be attributed to the conserved common process or common substances in spermatogenesis and maturation. An overwhelming majority of the influencing factors produce negative effects and a very few have positive ones, and their action mechanisms are mostly unknown. This review summarizes the results of current studies on the effect of high temperature on spermatogenesis and sperm maturation and on the sperm function in various species.

Modified Posterior Short-Segment Pedicle Screw Instrumentation for Lumbar Burst Fractures with Incomplete Neurological Deficit.

PURPOSE: We have introduced a method of modified posterior short-segment pedicle screw fixation and evaluated its clinical effects in treating lumbar burst fractures with incomplete neurological deficits. METHODS: The data from 22 patients with lumbar burst fracture and incomplete neurological deficits who had undergone modified posterior short-segment instrumentation with Schanz screw fixation from January 2012 to February 2018 in our clinic were evaluated in the present retrospective study. All Schanz screws were implanted in an oblique downward direction into the vertebrae above and below the injured vertebra (insertion depth, 90%-100%). The implants were removed ∼1 year after surgery. Neurological function, back pain, anterior and posterior body height ratio, kyphosis angle, percentage of canal compromise, fracture severity, and treatment-related complications were evaluated. RESULTS: Technical success was achieved in all 22 patients. No infection, instrument loosening or failure, or breakage was observed. Statistically significant improvements with regard to the anterior body height (P < 0.05) and posterior body height (P < 0.05) ratios, kyphosis angle, and percentage of canal compromise (P < 0.05) were observed at 1 week postoperatively or the final follow-up visit. No correction loss had occurred at the final follow-up examination. Postoperatively, all patients with neurological deficits had functional improvement equivalent to ≥1 grade on the American Spinal Injury Association impairment scale and fracture union. Back pain was greatly improved postoperatively. CONCLUSIONS: Short-segment Schanz screw fixation implanted in an oblique downward direction seems to be a promising method for lumbar burst fractures with incomplete neurological deficits because it provided good clinical and radiographic outcomes.

[The Research Advancement and Conception of the Deep-underground Medicine].

The 21th century is the century of exploring and utilizing the underground space. In the future, more and more people will spend more and more time living or/and working in the underground space. However,we know little about the effect on the health of human caused by the underground environment. Herein,we systematically put forward the strategic conception of the deep-underground medicine,in order to reveal relative effects and mechanism of the potential factors in the deep underground space on human's physiological and psychological healthy,and to work out the corresponding countermeasures. The original deep-underground medicine includes the following items. ①To model different depth of underground environment according to various parameters (such as temperature,radiation,air pressure, rock,microorganism), and to explore their quantitative character and effects on human health and mechanism. ② To study the psychological change, maintenance of homeostasis and biothythm of organism in the deep underground space. ③ To learn the association between psychological healthy of human and the depth, structure, physical environment and working time of underground space. ④ To investigate the effect of different terrane and lithology on healthy of human and to deliberate their contribution on organism growth. ⑤ To research the character and their mechanism of growth,metabolism,exchange of energy,response of growth, aging and adaptation of cells living in deep underground space. ⑥ To explore the physiological feature,growth of microbiome and it's interaction with host in the deep underground space. ⑦ To develop deep-underground simulation space, the biologically medical technology and equipments. As a research basis,a deep-underground medical lab under a rock thickness of about 1 470 m has been built,which aims to operate the research of the effect on living organism caused by different depth of underground environment.

Design and Antiproliferative Evaluation of Novel Sulfanilamide Derivatives as Potential Tubulin Polymerization Inhibitors.

A series of sulfanilamide-1,2,3-triazole hybrids were designed by a molecular hybridization strategy and evaluated for antiproliferative activity against three selected cancer cell lines (MGC-803, MCF-7 and PC-3). The detailed structure-activity relationships for these sulfanilamide-1,2,3-triazole hybrids were investigated. All these sulfanilamide-1,2,3-triazole hybrids exhibited moderate to potent activity against all cell lines. In particular 4-methyl-N-((1-(3-phenoxybenzyl)-1H-1,2,3-triazol-4-yl)methyl)benzenesulfonamide (11f) showed the most potent inhibitory effect against PC-3 cells, with an IC50 value of 4.08 µM. Furthermore, the tubulin polymerization inhibitory activity in vitro of compound 11f was 2.41 µM. These sulfanilamide hybrids might serve as bioactive fragments for developing more potent antiproliferative agents.

Clinical characteristics and prognosis of primary Waldeyer's ring and lymph node diffuse large B-cell lymphoma in the rituximab era.

This study was to compare the clinical characteristics and prognosis of Waldeyer's ring diffuse large B-cell lymphoma (WR-DLBCL) and lymph node DLBCL (LN-DLBCL) in the rituximab era. Before propensity score-matched (PSM), WR-DLBCL group shows more favorable clinical characteristics than LN-DLBCL group. After PSM, there was no significant difference in the response rate and survivals between them. The 5-year PFS and OS rates were 65.0% and 78.6% for WR-DLBCL group, respectively, and 53.7% and 66.1% for LN-DLBCL group, respectively. In WR-DLBCL group, ECOG score, Ann Arbor stage, B symptoms and IPI were associated with poor PFS and OS. In LN-DLBCL group, ECOG score, Ann Arbor stage, LDH, and IPI were significant factors to PFS and OS. Multivariate analysis showed that Ann Arbor stage was the only significant factor to PFS for WR-DLBCL group, for LN-DLBCL group, Ann Arbor stage and IPI were independent factors to PFS, LDH was the only significant factor to OS. WR-DLBCL was associated with more favorable clinical characteristics compared with LN-DLBCL, whereas, WR involvement itself did not have a real favorable prognostic significance. The PFS and OS of DLBCL were largely dependent on other prognostic factors such as Ann Arbor stage, LDH or IPI.

Association between neutrophil-to-lymphocyte ratio and differentiated thyroid cancer: a meta-analysis.

The association between neutrophil-to-lymphocyte ratio (NLR) and differentiated thyroid cancer (DTC) is undecided. To rectify this question, we conducted a systematic meta-analysis based on 7 prospective cohort studies published between 2013 and 2015, comprising 7349 patients. Six of these cohorts included pretreatment (baseline) NLR data for patients with thyroid nodules. The meta-analysis of these 6 cohorts showed that the NLR of patients with DTC (4617 cases) was statistically similar to patients with benign nodules only (1666 cases), with a mean difference (MD) of 0.19 (95% CI: -0.09 to 0.46; I2 = 93%; P < 0.001). No significant difference in NLR was found between patients with DTC and patients with benign nodules. Two studies addressed an association between NLR and papillary thyroid carcinoma in patients stratified by age <45 and ≥45 years (496 and 891 cases, respectively); the pooled MD was 0.09 (95% CI: -0.37 to 0.55; I2 = 92.2%, P < 0.001). An elevated NLR seems not a reliable indicator of progressing DTC in patients with goiters, and there was no difference in NLR between patients aged <45 years and those aged ≥45 years. Well-designed and large-scale investigations are warranted to understand the value of NLR in the prognosis of DTC.

Dendritic cells induce Tc1 cell differentiation via the CD40/CD40L pathway in mice after exposure to cigarette smoke.

Dendritic cells and CD8(+) T cells participate in the pathology of chronic obstructive pulmonary disease, including emphysema, but little is known of the involvement of the CD40/CD40L pathway. We investigated the role of the CD40/CD40L pathway in Tc1 cell differentiation induced by dendritic cells in a mouse model of emphysema, and in vitro. C57BL/6J wild-type and CD40(-/-) mice were exposed to cigarette smoke (CS) or not (control), for 24 wk. In vitro experiments involved wild-type and CD40(-/-) dendritic cells treated with CS extract (CSE) or not. Compared with the control groups, the CS mice (both wild type and CD40(-/-)) had a greater percentage of lung dendritic cells and higher levels of major histocompatability complex (MHC) class I molecules and costimulatory molecules CD40 and CD80. Relative to the CS CD40(-/-) mice, the CS wild type showed greater signs of lung damage and Tc1 cell differentiation. In vitro, the CSE-treated wild-type cells evidenced more cytokine release (IL-12/p70) and Tc1 cell differentiation than did the CSE-treated CD40(-/-) cells. Exposure to cigarette smoke increases the percentage of lung dendritic cells and promotes Tc1 cell differentiation via the CD40/CD40L pathway. Blocking the CD40/CD40L pathway may suppress development of emphysema in mice exposed to cigarette smoke.

Localization of Anterosuperior Point of Transverse-sigmoid Sinus Junction Using a Reference Coordinate System on Lateral Skull Surface.

BACKGROUND: During craniotomies using the transpetrosal-presigmoid approach, exposure of the sigmoid sinus remains an essential but hazardous step. In such procedures, accurate localization of the anterosuperior point of the transverse-sigmoid sinus junction (ASTS) is very important for reducing surgical morbidity. This study aimed to create an accurate and practical method for identifying the ASTS. METHODS: On the lateral surfaces of 40 adult skulls (19 male skulls and 21 female skulls), a rectangular coordinate system was defined to measure the x and y coordinates of two points: the ASTS and the squamosal-parietomastoid suture junction (SP). With the coordinate system, the distribution characteristics of the ASTS were statistically analyzed and the differences between the ASTS and SP were investigated. RESULTS: For ASTS-x, significant differences were found in different sides (P = 0.020); the ASTS-x in male skulls was significantly higher on the right side (P = 0.017); there was no significant difference between the sides in female skulls. There were no significant differences in gender or interaction of gender and side for ASTS-x, and for ASTS-y, there were no significant differences in side, gender, or interaction of gender and side. For both sides combined, the mean ASTS-x was significantly higher than the mean SP-x (P = 0.003) and the mean ASTS-y was significantly higher than the mean SP-y (P = 0.011). CONCLUSIONS: This reference coordinate system may be an accurate and practical method for identifying the ASTS during presigmoid craniotomy. The SP might be difficult to find during presigmoid craniotomy and, therefore, it is not always a reliable landmark for defining the ASTS.

Oridonin suppress cell migration via regulation of nonmuscle myosin IIA.

Oridonin, which is isolated from Chinese herb Rabdosia rubescens (Hemsl.) Hara, has been implicated in regulation of tumor cell migration and invasion. In this study, treatment with oridonin enhanced the phosphorylation of myosin regulatory light chain (T18/S19) that regulates the ATPase activity of myosin IIA. Meanwhile, stress fibers were significantly more prominent after oridonin incubation, which impaired cell migration in transwell migration assays. All of these effects may be caused by the decreased interaction between myosin IIA and myosin phosphatase complex, but not kinases. Our data provide clear evidence of this novel pharmacological function for oridonin in treating cancer cell migration.

Relativistic baryonic jets from an ultraluminous supersoft X-ray source.

The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Hα emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1's soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.

[Correlation of TLR2 and TLR4 gene polymorphisms with the susceptibility and recurrence of condyloma acuminatum].

OBJECTIVE: To explore the correlation of the gene polymorphisms of Toll-like receptor 2 ( TLR2) and TLR4 with the susceptibility and recurrence of condyloma acuminatum (CA). METHODS: Using Snapshot, we detected the gene polymorphisms of TLR2 597(T/C), 1350(T/C), 15607(A/G), and 2258(G/A) and TLR4 896(A/G) and 1196(C/T) in the peripheral blood of 140 CA patients and 105 HPV-negative controls. We made comparisons between the CA patients and controls as well as between the cases of recurrent CA and those of non-recurrence at 6 months after treatment. RESULTS: There were 72, 48, and 20 cases of genotype TT, TC, and CC of TLR2 597 (T/C), respectively, in the CA patients, as compared with 71, 31, and 3 cases in the controls. The gene frequency of mutant C was 31. 43% in the patients, significantly higher than 17.62% in the controls (χ2 = 12.04, P < 0.01), and it was 38.68% in the recurrent cases, remarkably higher than 27.01% in the non-recurrent cases (χ2 = 4.16, P < 0.05). There were 74, 49, and 17 cases of genotype TT, TC, and CC of TLR2 1350( T/C), respectively, in the CA patients, as compared with 73, 29, and 3 cases in the controls. The gene frequency of mutant C was 29. 64% in the patients, significantly higher than 16. 67% in the controls (χ2 =11.05, P < 0.01), and it was 36.79% in the recurrent cases, markedly higher than 25. 29% in the non-recurrent cases (χ2 = 4.18, P < 0.05). There were 44, 66, and 30 cases of genotype AA, AG, and GG of TLR2 15607(A/G), respectively, in the CA patients, as compared with 26, 58, and 21 cases in the controls. There was no significant difference in the gene frequencies of mutant G between the two groups (χ2 = 0.33, P > 0.05). No mutant genes of TLR2 2508 (G/A) or TLR4 896(A/G) and 1196(C/ T) were detected in either the CA patients or the controls. Linkage disequilibrium analysis showed a tight linkage between TLR2 597 (T/C) and 1350(T/C) (D' = 1, r2 = 0.93). CONCLUSION: TLR2 597(T/C) is tightly linked to 1350(T/C), which is correlated with both the susceptibility and the recurrence of condyloma acuminatum.

Pilomatrix carcinoma on the left side of the parotid region: A case report and review of the literature.

Pilomatrix carcinoma (PC) is a rare neoplasm, particularly in the parotid region. Thus, it is easily misdiagnosed and an optimal treatment regimen has not yet been established. The present study reports the case of a 43-year-old female who presented with a PC of the parotid region and reviews the associated published literature. The patient underwent three surgical excisions prior to the tumor being completely removed, and was misdiagnosed four times prior to the correct diagnosis. Once the tumor was completely removed, the patient received radiation therapy (RT). At the 2-year follow-up, the patient remained free of local recurrence and metastasis. To the best of our knowledge, only 3 cases of PC on the parotid region have been reported. Although an optimal treatment regimen has not been established, surgery with wide margins is recommended, with RT and chemotherapy producing mixed results.

Sesquiterpenes from the fruits of Illicium jiadifengpi and their anti-hepatitis B virus activities.

Two new compounds, 2S-hydroxyl-jiadifenolide (1) and jiadifenlactone acid (2), and eight known compounds were isolated from the fruits of Illicium jiadifengpi. Their structures were analysed using several spectroscopic techniques, including 1D-, 2D-NMR and HR-ESI-MS experiments. The anti-hepatitis B virus (HBV) activities of the isolates were evaluated via HBV transfection of the Hep G2.2.15 cell line. The inhibitory rates of the most active compounds, compounds 4 and 5, on the HBeAg and HBsAg expression were 28.85±3.15% and 17.53±1.81% and 37.93±2.74% and 23.47±9.52% at concentrations of 64.94µM and 61.35µM, respectively.

Electrochemical performance and detection of 8-Hydroxy-2'-deoxyguanosine at single-stranded DNA functionalized graphene modified glassy carbon electrode.

8-Hydroxy-2'-deoxyguanosine (8-OH-dG) is the most abundant oxidative product of DNA and it is also considered to be a biomarker of oxidative DNA damage. In this work, a novel biosensor was fabricated by combining the biocompatibility of single-stranded DNA (ss-DNA) and the excellent conductivity of graphene nanosheets (GNs). The biosensor showed high electrocatalytic activity to the oxidation of 8-OH-dG. The sensitivities were 13.23 (±0.03)µA µM(-1), 5.827 (±0.008) µA µM(-1) and 3.086 (±0.005) µA µM(-1) in the concentration ranges of 0.0056-1.155 µM, 1.155-11.655 µM and 11.655-36.155 µM, respectively. The detection limit was 0.875 nM (S/N=3). Furthermore, the electrochemical behavior of 8-OH-dG was also investigated in detail in the presence of uric acid. And the results showed that uric acid had interference with the trace detection of 8-OH-dG. But it can be eliminated completely by uricase. The as-prepared ss-DNA/GNs/GCE will be promising for the detection of 8-OH-dG in real samples.

Production of a fragment of glycoprotein G of herpes simplex virus type 2 and evaluation of its diagnostic potential.

INTRODUCTION: Herpes simplex virus type 2 (HSV-2) is the most common cause of genital herpes. Glycoprotein G (gG) is a prototype antigen for type-specific serodiagnosis distinguishing between HSV type 1 (HSV-1) and HSV-2 infections. As immunological diagnosis kits for accurate differentiation between HSV-1 and HSV-2 antibodies can be expensive, there is a need to develop a convenient, sensitive, specific and cost-effective serodiagnostic kit. METHODS: We successfully expressed a fragment of gG comprising residues 321-580 of HSV-2 with histidine tag (gG(321-580His)) in a Bac-to-Bac baculovirus expression system, which had an antigenicity similar to its native counterpart. An indirect enzyme-linked immunosorbent assay (ELISA) was developed using gG(321-580His) as the diagnostic antigen and evaluated by comparison with a commercial HerpeSelect 2 ELISA immunoglobulin G kit as reference. RESULTS: In testing 318 field serum samples, the diagnostic relative sensitivity and specificity of the developed gG(321-580His)-ELISA test in qualitative comparison with the commercial kit were 93.81% and 96.74%, respectively, and the accuracy was 94.65%. CONCLUSION: The study indicates that gG(321-580His) has a high diagnostic potential for HSV-2 virus serodiagnosis in humans.

A new sesquiterpene lactone from the fruits of Illicium henryi.

AIM: To study the chemical constituents of the fruits of Illicium henryi. METHOD: Chromatographic separations on silica gel, Sephadex LH-20 gel and MCI gel were used to isolate the compounds. The structures were elucidated based on extensive spectroscopic data analyses. RESULTS: Seven compounds were obtained and their structures were identified as 10-benzoyl-cycloparvifloralone (1), cycloparvifloralone (2), 2α-hydroxycycloparviforalone (3), henrylactone B (4), merrillianone (5), henrylactone C (6) and 7, 14-ortholactone- 3-hydroxyfloridanolide (7). CONCLUSION: Compound 1 is a new sesquiterpene lactone. The tested compounds showed weak anti-HBV activities on HBV surface antigen (HBsAg) secretion and HBV e antigen (HBeAg) secretion using Hep G2.2.15 cell line.

Puzzling accretion onto a black hole in the ultraluminous X-ray source M 101 ULX-1.

There are two proposed explanations for ultraluminous X-ray sources (ULXs) with luminosities in excess of 10(39) erg s(-1). They could be intermediate-mass black holes (more than 100-1,000 solar masses, M sun symbol) radiating at sub-maximal (sub-Eddington) rates, as in Galactic black-hole X-ray binaries but with larger, cooler accretion disks. Alternatively, they could be stellar-mass black holes radiating at Eddington or super-Eddington rates. On its discovery, M 101 ULX-1 had a luminosity of 3 × 10(39) erg s(-1) and a supersoft thermal disk spectrum with an exceptionally low temperature--uncomplicated by photons energized by a corona of hot electrons--more consistent with the expected appearance of an accreting intermediate-mass black hole. Here we report optical spectroscopic monitoring of M 101 ULX-1. We confirm the previous suggestion that the system contains a Wolf-Rayet star, and reveal that the orbital period is 8.2 days. The black hole has a minimum mass of 5 M sun symbol, and more probably a mass of 20 M sun symbol-30 M sun symbol, but we argue that it is very unlikely to be an intermediate-mass black hole. Therefore, its exceptionally soft spectra at high Eddington ratios violate the expectations for accretion onto stellar-mass black holes. Accretion must occur from captured stellar wind, which has hitherto been thought to be so inefficient that it could not power an ultraluminous source.