ABSTRACT
All stellar-mass black holes have hitherto been identified by X-rays emitted from gas that is accreting onto the black hole from a companion star. These systems are all binaries with a black-hole mass that is less than 30 times that of the Sun1-4. Theory predicts, however, that X-ray-emitting systems form a minority of the total population of star-black-hole binaries5,6. When the black hole is not accreting gas, it can be found through radial-velocity measurements of the motion of the companion star. Here we report radial-velocity measurements taken over two years of the Galactic B-type star, LB-1. We find that the motion of the B star and an accompanying Hα emission line require the presence of a dark companion with a mass of [Formula: see text] solar masses, which can only be a black hole. The long orbital period of 78.9 days shows that this is a wide binary system. Gravitational-wave experiments have detected black holes of similar mass, but the formation of such massive ones in a high-metallicity environment would be extremely challenging within current stellar evolution theories.
ABSTRACT
AIM: To study the effects of danhong huayu koufuye (DHK) on fasting blood glucose (FBG) and diabetic retinopathy (DR) in streptozotocin (STZ)-induced type 1 diabetic rats to facilitate the rational usage of this drug. METHODS: Diabetic rats were induced by injection of a single dose of STZ intraperitoneally at 50mg/kg. Flash electroretinogram (FERG) and oscillatory potentials (OPs) were used to measure retinal function. The microvascular perfusion of ears was performed to study the microcirculation in rats. FBG, body-weight, and 24-h urine volume, water intake and diet intake were also assessed. RESULTS: DHK had no effect on FBG in normal rats. However, STZ + DHK group were significantly different from those of Model and moved toward those of normal control. It reversed the increase in diet intake (P≤0.05 vs model control) and the loss in body-weight (P≤0.05 vs model control) in diabetic rats. DHK decreased the FBG of diabetic rats by 25.6% (P≤0.05) and 37.9% (P≤0.01) after 14 and 21 days administration as compared with the model control, respectively. Moreover, DHK significantly increased the FERG b-wave amplitude by 80% (P≤0.05 vs model control) and decreased the FERG b-wave latency by 15.3% (P≤0.01 vs model control) after 24 days administration. The OP(1) and OP(2) amplitudes in DHK group were 2.6 (P≤0.01) and 2.0 (P≤0.01) times of model group after 24 days of DHK treatment, respectively. At the same time, OP1 and OP2 latencies in DHK group reduced by 16.0% (P≤0.001) and 14.7% (P≤0.001) as compared with the model control, respectively. Furthermore, the microvascular perfusion of DHK group was 2.4 times of model group (P≤0.001) after 21 days administration. CONCLUSION: DHK had no effect on normal FBG. But it had antihyperglycemic activity, and had a preventive and therapeutic effect on DR in diabetic rats.
