[A prospective cohort study on refractive status of schoolchildren in Huangzhong District, Xining City, Qinghai Province]

Objective: To determine the characteristics and progress of the visual acuity and refractive state of schoolchildren in Huangzhong District, Xining City, Qinghai Province in China. Methods: Cohort study. Department of Ophthalmology, Beijing Children's Hospital carried out a cohort study by collecting the visual acuity and refractive state of Grade 1-5 schoolchildren among 16 primary schools in Huangzhong District, Xining City, Qinghai Province in September 2020 and July 2021. Cycloplegic retinoscopy with eye drop which contained tropicamide (0.5%) and phenylephrine hydrochloride (0.5%) was performed in children with low vision(<1.0). Myopia was defined as the spherical equivalent (SE) ≤-0.5 D after cycloplegic retinoscopy. Measurement data was analyzed by t-test and enumeration data was analyzed by χ² test. Multiple linear regression was used to analyze the influencing factors. Results: The 2 489 individuals with repeated tests in two years were included in the follow-up study, among whom the prevalence of myopia was 26.24%(653/2 489) in 2020, while 32.94% (820/2 489)respectively in 2021. The incidence of myopia in one school year from grades 1 to 5 was 11.19%(47/420), 5.44%(21/386), 6.39%(25/391), 11.52%(44/382) and 11.67%(30/257). The average SE of children in all grades in 2021 increased negatively from the previous year (Grade 1 to Grade 5 increased respectively: 0.40 D, 0.69 D, 0.62 D, 0.52 D and 0.37 D). Conclusions: The prevalence of myopia among schoolchildren in Huangzhong District, Xining City, Qinghai Province was relatively high. There were two peaks of myopia incidence in the first, fourth and fifth grades. Female, age, and the baseline of SE were the related influencing factors for myopia progression.

[The clinical features of laryngeal malignant lymphoma with 5 cases reported]

OBJECTIVE

To improve the diagnosis and treatment of laryngeal malignant lymphoma.

METHOD

Clinical features of 5 cases were reported and recent literatures were reviewed.

RESULT

2 cases presented with large ulcerated lesions and their laryngeal structure were destroyed, their prognosis were poor. Another 3 cases were local primary lesions, they were generally associated with a relatively short history of hoarseness and dysphagia and exhibited grey-white neoplasms with preferential involvement in the supraglottic parts of larynx, but non-ulcerated lesions, they were treated with operation and radiotherapy or chemotherapy or combinations. The prognosis were very well after 2 to 6 years follow up.

CONCLUSION

It is important for the local primary lesion to be diagnosed correctly for the treatment and prognosis.

PsaD is required for the stable binding of PsaC to the photosystem I core protein of Synechococcus sp. PCC 6301

The psaC gene product from Synechococcus sp. PCC 7002 and the psaD gene product from Nostoc sp. PCC 8009 were synthesized in Escherichia coli and purified to homogeneity. Incubation of the PsaC apoprotein with the Synechoccus sp. PCC 6301 photosystem I core protein in the presence of FeCl3, Na2S, and beta-mercaptoethanol resulted in a time-dependent transition in the flash-induced absorption change from a 1.2-ms, P700+ FX- back-reaction to a long-lived, P700+ [FA/FB]- back-reaction. ESR studies showed that FB and FA were photoreduced about equally at 19 K, and while the resonances were shifted upfield, they remained as broad as in the free PsaC holoprotein. When the reconstituted complex was purified in a sucrose gradient containing 0.1% Triton X-100, most of the optical absorption transient reverted to that characteristic of the P700+ FX- back-reaction. Addition of purified PsaD to the incubation mixture led to a greater extent of recovery of electron flow to FA/FB for any given concentration of PsaC. ESR studies showed that FA, rather than FB, became the preferred electron acceptor at 19 K; moreover, the resonances moved upfield and sharpened to become nearly identical with those of a control photosystem I complex. When the sample was purified in a sucrose gradient containing 0.1% Triton X-100, the long-lived P700+ [FA/FB]- optical transient remained stable. Analysis by denaturing polyacrylamide gel electrophoresis showed that the PsaC and PsaD proteins had rebound to the photosystem I core. The data indicate that although PsaC can bind loosely, the presence of PsaD leads to a stable, isolatable photosystem I complex which is spectroscopically indistinguishable from the native complex. Since a PsaC1 fusion protein which contains an amino-terminal extension of five amino acids (MEHSM...) does not bind in the absence of PsaD [Zhao, J., et al. (1990) FEBS Lett. 276, 175-180], the N-terminus of the PsaC protein could provide a site of interaction with the photosystem I core. We propose that the binding of PsaC to the PsaA/PsaB heterodimer is potentiated by insertion of the FA/FB clusters into PsaC, and stabilized by the presence of PsaD.

Reconstitution of electron transport in photosystem I with PsaC and PsaD proteins expressed in Escherichia coli

A fusion protein, denoted PsaC1, which contains an amino-terminal extension of five amino acids (MEHSM...) and is derived from an in vitro modified form of the psaC gene of Synechococcus sp. PCC 7002, has been over-expressed in Escherichia coli. The product of the psaD gene of Nostoc sp. PCC 8009 has similarly been over-expressed. The PsaC1 and PsaD proteins can be combined with the photosystem I core protein of Synechococcus sp. PCC 6301 to reconstitute electron transport from P700 to the terminal FA/FB acceptors. Reconstitution was found to be absolutely dependent on reinsertion of the iron-sulfur clusters in the PsaC1 apoprotein and on the presence of the PsaD protein. This implies that the PsaC1 holoprotein does not bind solely to the PsaA/PsaB heterodimer but rather that its interaction with these proteins is mediated through the PsaD protein.

Sequential effects of sodium depletion on photosystem II in Synechocystis

Incubation of Synechocystis PCC 6714 in liquid medium devoid of Na+ results in a light-dependent loss in photosynthetic O2 evolving capacity within 1 h. Photosynthetic activity is fully restored and normal growth resumes after Na+ is supplied to culture medium of depleted cells. If external Na+ is provided as soon as inhibition becomes complete, normal photosynthesis is restored within 3 min. However, if cells are further illuminated for several h under Na+ stress, then full recovery takes much longer, and requires new protein synthesis. Electron transport assays using isolated membranes demonstrate that the immediate inhibition resulting from Na+ depletion involves the O2 evolving site, while the secondary effect requiring new protein synthesis occurs near the reaction center of Photosystem II. Experiments conducted at different pH values and in the absence of inorganic carbon demonstrate that within the short time duration of these experiments Na+ does not inhibit photosynthesis by restricting bicarbonate movement into the cells. These experiments extend previous results with other cyanobacteria which demonstrated that Ca2+ and Na+ stress cause reversible damage at a site near the reaction center of Photosystem II. The damage can be characterized as a primary ion effect at the oxygen evolving site and a secondary photoinhibition near the reaction center of Photosystem II.

Long-term follow-up observations of the therapeutic effect of PVNO on human silicosis

The effect of PVNO treatment on human silicosis was observed in 7 cases over a period of 9 years lasting from 1965 to 1974. The drug was given intramuscularly and by way of inhalation, respectively. The comparison of the radiographs taken before, during and 3 years after the administration of PVNO showed that during treatment the tendency of fibrotic progression was delayed in 4 cases while 2 cases were slightly progressive, and one was markedly progressive, 3 years after discontinuation of the PVNO treatment, only one case remained stable, two cases were slightly and 4 cases markedly progressive. These observations indicate that PVNO treatment may have an effect on the delay and control of silicosis progression in a portion of patients, but after discontinuation of the treatment further progression is possible.