[Efficacy and safety of intravitreal dexamethasone implant in diabetic macular edema patients with and without prior vitrectomy: a retrospective cohort study].

Objective: To evaluate the effectiveness and safety of intravitreal dexamethasone implant (IDI) in diabetic macular edema (DME) patients with and without prior vitrectomy. Methods: A retrospective cohort study was conducted on DME patients who received IDI treatment at the Aier Eye Hospital, Beijing from March 2018 to August 2020. Patients were divided into two groups according to whether they had undergone vitrectomy or not. Clinical and follow-up data, including best-corrected visual acuity (BCVA), intraocular pressure (IOP), central macular thickness (CMT), occurrence of ocular and systemic complications, and time to DME recurrence and retreatment, were collected before and after IDI injection at 15 days, 1, 2, 3, and 6 months. Statistical analyses were performed using t-test, Mann-Whitney U-test, χ2 test or Fisher's exact test, and generalized estimating equations. Results: Thirty-six patients (41 eyes) were included, with 19 patients (21 eyes) in the vitrectomy group and 17 patients (20 eyes) in the non-vitrectomy group. Compared with baseline, BCVA of eyes in the vitrectomy group was significantly improved at 15 days after IDI injection, with values of 1.00 (0.52, 1.31) and 0.61 (0.30, 1.00), respectively (Z=-2.10, P=0.036); BCVA of eyes in the non-vitrectomy group was significantly improved at 1 month after IDI injection, with values of 0.76 (0.60, 1.35) and 0.52 (0.10, 0.70), respectively (Z=-2.24, P=0.025). Compared with baseline, CMT of eyes in both groups was significantly reduced at all follow-up time points after 15 days of IDI injection (all P<0.05). In the vitrectomy group, CMT before and 15 days after injection were 487 (438, 661) µm and 389 (340, 553) µm, respectively (Z=-3.45, P<0.001); in the non-vitrectomy group, CMT before and 15 days after injection were 486 (410, 641) µm and 323 (290, 396) µm, respectively (Z=-4.07, P<0.001). There were no statistically significant differences in BCVA and CMT between the two groups at all follow-up time points (all P>0.05). The time to DME recurrence was 3.0 (3.0, 4.0) months in the vitrectomy group and 5.0 (4.0, 5.0) months in the non-vitrectomy group, with no significant difference between the two groups (P=0.675). Four eyes (19.0%) in the vitrectomy group and three eyes (15.0%) in the non-vitrectomy group had high IOP, with no significant difference (P=0.529). No severe ocular or systemic complications were observed in any patients. Conclusions: IDI treatment is safe and effective in DME patients with and without prior vitrectomy, with similar efficacy, but with faster onset of action in patients with prior vitrectomy. There was no significant difference in DME recurrence within 6 months after IDI injection between the two groups.

[Clinical features and significance of coagulation dysfunction in severe fever with thrombocytopenia syndrome].

To analyze the changes of coagulation function in severe fever with thrombocytopenia syndrome (SFTS) and its relationship with thrombocytopenia, and to explore its value as an early predictor of the severity of SFTS. The clinical data of 428 SFTS patients (70 deaths and 358 survivors) admitted to the Department of Infectious Disease at Wuhan Union Hospital from January 2014 to July 2020 were retrospectively analyzed. The differences of coagulation parameters and disseminated intravascular coagulation (DIC) scores between the two groups were compared. The results showed that abnormal coagulation function was commonly presented in SFTS patients. Bleeding was more frequent in mortality group (41.4% vs. 26.5%). The D-dimer levels in mortality patients were significantly higher above normal range. Activated partial thrombin time (APTT) and thrombin time (TT) were significantly prolonged. The levels of prothrombin time (PT), TT, APTT, international standardized ratio (INR) and D-dimer between mortality group and survival group started to separate from day 5-6. The difference of fibrinogen (FIB) level developed on day 7-8, while platelet counts between the two groups were significant different from day 9-10. The mortality rate increased according to the increase of baseline DIC score. When DIC score reached 6, the mortality rate surged to 66.67%. Excessive platelet consumption is mediated by significant coagulation abnormalities during disease course, and coagulation parameters are more sensitive than platelet count as an early predictor of severe SFTS.

[Characteristics of liver function changes in 111 elderly patients with COVID-19 pneumonia].

Objective: To retrospectively analyze the characteristics and influencing factors of liver function changes in 111 elderly patients with COVID-19 pneumonia. Methods: 111 elderly patients with COVID-19 admitted to the Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from February 5 to March 3, 2020 were enrolled. According to the severity of disease and liver function condition, they were divided into severe group (n=40), normal group (n=71), abnormal liver function group (n=86) and normal liver function group (n=25). The indexes related to liver function changes [total bilirubin (TBil), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT)] and related influencing factors were analyzed. Results: Among 111 cases, 86 (77.5%) had abnormal liver function of varying degrees, and 28 (25.2%) had liver injury. The abnormal rates of TBil, AST, ALP and GGT were significantly higher in the severe group than normal group (P<0.05). There were no significant differences in age, ribavirin, glucocorticoid and the application of lopinavir-ritonavir tablets between the abnormal liver function and the normal group (P>0.05). The proportion of male was significantly higher in the abnormal liver function than normal liver function group (P<0.05). Conclusion: Elderly COVID-19 patients have a higher proportion of abnormal liver function, and patients in the severe group are more likely to have higher level of TB, AST, ALP and GGT. The abnormal liver function may be related to the direct viral infection of the liver and the inflammatory immune response of the body after infection in elderly patients.

Pilot-based XPM nonlinearity compensator for CO-OFDM systems.

We experimentally verify that pilot-based nonlinearity compensation is effective for mitigating XPM in CO-OFDM systems, if SPM is compensated first. A 6-dB increase in the nonlinear limit was produced by pilot-based XPM compensation after a single-step SPM compensator in a 400-km link with periodic dispersion compensation. In addition, we use numerical simulations to show that the required bandwidth of the guard-band around the pilot is almost independent of the bandwidth of the data-carrying sidebands. The optimal ratio of pilot to signal power also decreases for higher bandwidth OFDM signals. Therefore, the overhead associated with transmitting the pilot decreases as the bandwidth of the signal increases.

Fiber nonlinearity precompensation for long-haul links using direct-detection optical OFDM.

The use of nonlinearity precompensation in direct-detection optical orthogonal frequency division multiplexed links is investigated by simulation. Because of the presence of a strong optical carrier its performance is poorer than for coherent systems: with compensation the signal quality is found to vary almost periodically across the signal band. We propose and explain the operation of two optical, one electrical and one computational method of removing this periodic variation. Optical filtering of one sideband at the receiver is most effective, but a substantial improvement can be obtained by a simple modification to the precompensation algorithm.