[Analysis of the incidence and reasons of the same-day cancellation of non-cataract ophthalmic ambulatory surgery].

Objective: To investigate the incidence and reasons of the same-day cancellation of non-cataract ophthalmic ambulatory surgery, and to provide a basis for further improvement of the medical quality of ophthalmic ambulatory surgery. Methods: The data of the appointment for ophthalmic ambulatory surgeries from December 1, 2020 to November 30, 2021, including the patient's general condition, disease diagnosis, proposed surgical arrangement, anesthesia method and the completion of the surgeries, were collected through the electronic medical record management system in Beijing Tongren Hospital, Capital Medical University. The total number and incidence of cancelled surgeries registered in the surgical center were analyzed, the incidence of cancelled surgeries of different ages, sexes, subspecialty surgical types, anesthesia methods, patient sources were analyzed, and the reasons for surgical cancellation were further analyzed. Results: A total of 10, 595 non-cataract ophthalmic day surgeries were applied, of which 827 were temporarily cancelled on the day of surgery, with a cancellation rate of 7.8%. The difference in the same-day surgery cancellation rate at different ages was statistically significant (P<0.001), of which the surgery cancellation rate in toddler and infants was the lowest, which was 2.1% (23/1 110) and 3.4% (2/59), respectively, while the surgery cancellation rate was the highest in elderly patients over 75 years old, at 10.4% (48/462). There was a statistically significant difference in surgical cancellation rates among different sub-specialties (P<0.001), with the lowest surgical cancellation rate in the tumor sub-specialty at 4.5% (33/732), while the corneal sub-specialty had the highest surgical cancellation rate at 14.3% (40/280), followed by the plastic sub-specialty with 11.8% (153/1 297). There were no statistically significant differences in the rate of surgical cancellation between different sexes, anesthesia methods or patients' home address (all P>0.05). The most common reason for same-day surgery cancellation was the absence of the patient on the day of surgery (49.7%, 479/827), followed by changes in the patient's general condition (18.4%, 152/827), and inadequate preoperative preparation (6.0%, 50/827). 64.3% (532/827) of the same-day surgical cancellations were considered to have been avoided by enhancing preoperative communication, consultation and management. Conclusions: The same-day cancellation rate of ambulatory surgery in non-cataract ophthalmology is 7.8%, of which the cancellation rate in elderly patients and in less invasive surgery are higher. The absence of the patient on the same day and the change of the patient's condition are the main reasons for the cancellation of surgery on the same day, and most of them are avoidable.

Regulation of CO on heterocyst differentiation and nitrate uptake in the cyanobacterium Anabaena sp. PCC 7120.

AIMS: The aim of the present investigation was to study the effects of different inorganic carbon and nitrogen sources on nitrate uptake and heterocyst differentiation in the culture of cyanobacterium Anabaena sp. PCC 7120. METHODS AND RESULTS: Anabaena was cultivated in media BG11 containing combined nitrogen and supplementary NaHCO3 or CO2. Cell growth, heterocyst differentiation, nitrate reductase (NR, EC 1.7.7.2), glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) and NO uptake were analysed. The cells cultivated in BG11(0) medium with aeration were taken as reference. Experimental results showed that the differentiation frequency of heterocysts when the cells were cultivated with elevated CO2 was higher than that of the cells grown with air or bicarbonate. Heterocysts appeared unexpectedly when CO2 was introduced into the medium containing nitrate. However, no heterocysts emerged when CO2 was added to medium containing NH or urea, or when NaHCO3 was supplied to the medium with nitrate. Both nitrate uptake rate and nitrate reduction enzyme activity were depressed by the supplement of CO2 to the culture. The activity of G6PDH was enhanced with the increase in heterocyst differentiation frequency. CONCLUSION: CO2 might compete with NO for energy and electrons in the uptake process and CO2 appears favoured. This led to a high intracellular C/N ratio and a relative N limitation. So the process of heterocyst differentiation was activated to supplement nitrogen uptake. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provided an attractive possibility to form more heterocysts by rapid growth of Anabaena cells cultivated in the medium containing nitrate in order to increase nitrogen fixation and hydrogen production.

[Photoautotrophic cultivation of Synechococcus sp. PCC7002 in photobioreactor].

The Photoautotrophic cultivation of Synechococcus sp. PCC 7002 in a 15 L-airlift photobioreactor was carried out. The changes of light intensity with cell density and optical length in the cultivation system were investigated. Based on experimental results, the light attenuation could be described by I = I0exp [-(-0.0239 + 0.0777 OD750).L]. The effects of the variations of light intensity, CO2 concentration in gas inlet and culture temperature on the growth of cells during the cultivation process have also been studied. The optimized condition was determined and a high dry cell density of 3.4 g/L was obtained. The volumetric productivity reached 0.57 g/(L.d) under the optimized condition.

The effects of immobilization on the biochemical, physiological and morphological features of Anabaena azollae.

Anabaena azollae, a presumptive isolate from Azolla filiculoides, was immobilized in polyurethane foam, hydrophilic polyvinyl foam and alginate. When viewed by low-temperature scanning electron microscopy a thick mucilage layer covered the surface of both cells and matrix; this closely resembles the mode of attachment of the symbiont Anabaena in the Azolla leaf cavity. The heterocyst frequency of the immobilized A. azollae doubled relative to free-living cells and reached a level of 14-17%. Immobilization induced increases in both hydrogen production via nitrogenase or hydrogenase and in the rates and stabilization of acetylene reduction (N2-fixation). Ammonia production by immobilized cells with L-methionine-D,L-sulfoximine (MSX) is greater than that of freeliving cells. Immobilized cells without MSX were, however, able to excrete ammonium at lower rates thus emulating the characteristic of the symbiotic cyanobacteria (A. azollae) in the leaf cavity of Azolla.

[Mixotrophic cultivation of Synechocystis sp. 6803: influences of light intensity and glucose].

The growth characteristics and the effects of glucose and light on the growth of Synechocystis sp. PCC6803 under mixotrophic conditions have been investigated. An exponential growth phase had been observed before glucose was consumed. The results showed that both of light intensity and glucose concentration had obvious effects on the mixotrophic growth of Synechocystis sp. PCC6803: the specific growth are decreased with the increase of glucose concentration at light; the specific growth rate and biomass/glucose yield increased with light intensity, ranging from 15-55 microE.m-2.s-1; when light intensity was higher than 55 microE.m-2.s-1, light saturation appeared.