[The value of cardiac MRI in the risk stratification in patients with hypertrophic cardiomyopathy]

Objective: To explore the value of cardiac magnetic resonance imaging (CMR) in the risk stratification of hypertrophic cardiomyopathy (HCM). Methods: HCM patients who underwent CMR examination in Fuwai Hospital between March 2012 and May 2013 were retrospectively enrolled. Baseline clinical and CMR data were collected and patient follow-up was performed using telephone contact and medical record. The primary composite endpoint was sudden cardiac death (SCD) or and equivalent event. The secondary composite endpoint was all-cause death and heart transplant. Patients were divided into SCD and non-SCD groups. Cox regression was used to explore risk factors of adverse events. Receiver operating characteristic (ROC) curve analysis was used to assess the performance and the optimal cut-off of late gadolinium enhancement percentage (LGE%) for the prediction of endpoints. Kaplan-Meier and log-rank tests were used to compare survival differences between groups. Results: A total of 442 patients were enrolled. Mean age was (48.5±12.4) years and 143(32.4%) were female. At (7.6±2.5) years of follow-up, 30 (6.8%) patients met the primary endpoint including 23 SCD and 7 SCD equivalent events, and 36 (8.1%) patients met the secondary endpoint including 33 all-cause death and 3 heart transplant. In multivariate Cox regression, syncope(HR=4.531, 95%CI 2.033-10.099, P<0.001), LGE% (HR=1.075, 95%CI 1.032-1.120, P=0.001) and left ventricular ejection fraction (LVEF) (HR=0.956, 95%CI 0.923-0.991, P=0.013) were independent risk factors for primary endpoint; Age (HR=1.032, 95%CI 1.001-1.064, P=0.046), atrial fibrillation (HR=2.977, 95%CI 1.446-6.131, P=0.003),LGE% (HR=1.075, 95%CI 1.035-1.116, P<0.001) and LVEF (HR=0.968, 95%CI 0.937-1.000, P=0.047) were independent risk factors for secondary endpoint. ROC curve showed the optimal LGE% cut-offs were 5.1% and 5.8% for the prediction of primary and secondary endpoint, respectively. Patients were further divided into LGE%=0, 0<LGE%<5%, 5%≤LGE%<15% and LGE%≥15% groups. There were significant survival differences between these 4 groups whether for primary endpoint or secondary endpoint (all P<0.001) and the accumulated incidence of primary endpoint was 1.2% (2/161), 2.2% (2/89), 10.5% (16/152) and 25.0% (10/40), respectively. Conclusion: LGE is an independent risk factor for SCD events as well as all-cause death and heart transplant. LGE is of important value in the risk stratification in patients with HCM.

Infection Characteristics and Physical Prevention Strategy of Panax notoginseng Round Spot Disease Caused by Mycocentrospora acerina

Panax notoginseng round spot disease (PRSD), caused by Mycocentrospora acerina, is the main leaf disease occurring in cultured P. notoginseng. Aiming to find a safe and efficient control method for PRSD, we studied the disease characteristics of PRSD and the optimal growth conditions of M. acerina and evaluated the efficacy of rain-shelter cultivation in PRSD control. Moreover, we described M. acerina based on morphological characterization and molecular analyses (ITS, ACT, LSU, and TEF-1α). The optimum temperature for M. acerina conidial germination was found to be 14 to 22°C. Furthermore, leaf surface wetness for at least 4 h is required for conidial germination, and conidia can successfully infect P. notoginseng when the leaf wetness lasts for more than 8 h. Additionally, rainwater splashing determines the conidial transfection distance, which is less than 2 m. Finally, our study revealed that rain-shelter cultivation is an effective and simple physical prevention strategy to control PRSD, with an average efficacy of up to 100%.

[Distribution and suitable habitats of ticks in the Yangtze River Delta urban agglomeration]

OBJECTIVE

To investigate the current distribution of ticks and predict the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2017, so as to provide insights into tick control and management of tick-borne diseases in these areas.

METHODS

All publications pertaining to tick and pathogen distribution in the Yangtze River Delta urban agglomeration were retrieved, and the geographical location of tick distribution was extracted. The effects of 19 climatic factors on the distribution of ticks were examined using the jackknife method, including the mean temperature of the wettest quarter, precipitation of the coldest quarter, mean temperature of the driest quarter, maximum temperature of the warmest month, precipitation of the driest month, minimal temperature of the coldest month, annual precipitation, mean daily temperature range, precipitation seasonality, annual temperature range, temperature seasonality, annual mean temperature, mean temperature of the warmest quarter, precipitation of the wettest quarter, isothermality, mean temperature of the coldest quarter, precipitation of the wettest month, precipitation of the driest quarter and precipitation of the warmest quarter. The distribution of ticks was analyzed in 2020 using the maximum entropy (MaxEnt) model, and the potential suitable habitats of ticks were predicted in 2070 using the MaxEnt model based on climatic data.

RESULTS

A total of 380 Chinese and English literatures were retrieved, and 148 tick distribution sites were extracted, with 135 sites included in the subsequent analysis. There were 7 genera (Haemaphysalis, Rhipicephalus, Ixodes, Dermacentor, Boophilus, Hyalomma and Amblyomma) and 27 species of ticks detected in the Yangtze River Delta urban agglomeration. The climatic factors affecting the distribution of ticks in the Yangtze River Delta urban agglomeration mainly included the mean temperature of the wettest quarter and the precipitation of the coldest quarter, with 26.1% and 23.6% contributions to tick distributions. The high-, medium- and low-suitable habitats of ticks were 20 337.08, 40 017.38 km² and 74 931.43 km² in the Yangtze River Delta urban agglomeration in 2020, respectively. The climate changes led to south expansion of the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2070, and the total areas of suitable habitats of ticks was predicted to increase by 18 100 km². In addition, the high-, medium- and low-suitable habitats of ticks were predicted to increase to 24 317.84, 45 283.02 km² and 83 766.38 km² in the Yangtze River Delta urban agglomeration in 2070, respectively.

CONCLUSIONS

Multiple tick species are widespread in the Yangtze River Delta urban agglomeration, and the future climate changes may lead to expansion of tick distribution in these areas.

Aberrations in peripheral inflammatory cytokine levels in substance use disorders: a meta-analysis of 74 studies

AIMS

To characterize the peripheral inflammatory cytokine profile in people with substance use disorders (SUDs).

DESIGN

Systematic review and meta-analysis.

SETTING

Clinical studies that evaluated peripheral blood inflammatory cytokine levels in patients with SUDs and healthy controls PARTICIPANTS: SUD patients and healthy controls.

MEASUREMENTS

PubMed and Web of Science were systematically searched for relevant studies. Two investigators independently selected studies and extracted data. A total of 77 articles were included in the meta-analysis, containing 5649 patients with SUDs and 4643 healthy controls. Data were pooled using a random-effects model by the Comprehensive Meta-Analysis version 2 software.

FINDINGS

Concentrations of interleukin (IL)-6) in 32 studies, tumor necrosis factor (TNF)-α in 28 studies, IL-10 in 20 studies, IL-8 in 17 studies, C-reactive protein in 14 studies, IL-4 in 10 studies, IL-12 in seven studies, monocyte chemoattractant protein (MCP)-1 in 6 studies, TNF-receptor 2 (TNF-R2) in four studies and granulocyte-macrophage colony-stimulating factor (GM-CSF) in three studies were significantly higher in patients with SUDs compared with healthy controls, while concentrations of leptin in 14 studies were significantly lower in patients with SUDs compared with healthy controls. The findings were inconclusive for the associations between interferon-γ, IL-1β, IL-2, IL-1 receptor antagonist (IL-1RA), transforming growth factor (TGF)-β1, G-CSF, C-C motif chemokine 11, TGF-α and SUDs.

CONCLUSIONS

People with substance use disorders (SUDs) appear to have higher peripheral concentrations of IL-4, IL-6, IL-8, IL-10, IL-12, TNF-α, C-reactive protein, MCP-1, TNF-R2 and GM-CSF and lower peripheral concentrations of leptin than people without SUDs. This strengthens the view that SUD is accompanied by an inflammatory response.

Effects of soybean isoflavones on the growth performance, intestinal morphology and antioxidative properties in pigs

Soybean meal is rich in soybean isoflavones, which exhibit antioxidant, anti-inflammatory, antiviral and anticancer functions in humans and animals. This study was conducted to investigate the effects of soybean isoflavones on the growth performance, intestinal morphology and antioxidative properties in pigs. A total of 72 weaned piglets (7.45 ± 0.13 kg; 36 males and 36 females) were allocated into three treatments and fed corn-soybean meal (C-SBM), corn-soy protein concentrate (C-SPC) or C-SPC supplemented with equal levels of the isoflavones found in the C-SBM diet (C-SPC + ISF) for a 72-day trial. Each treatment had six replicates and four piglets per replicate, half male and half female. On day 42, one male pig from each replicate was selected and euthanized to collect intestinal samples. The results showed that compared to pigs fed the C-SPC diet, pigs fed the C-SBM and C-SPC + ISF diets had higher BW on day 72 (P < 0.05); pigs fed the C-SBM diet had significantly higher average daily gain (ADG) during days 14 to 28 (P < 0.05), with C-SPC + ISF being intermediate; pigs fed the C-SBM diet tended to have higher ADG during days 42 to 72 (P = 0.063), while pigs fed the C-SPC + ISF diet had significantly higher ADG during days 42 to 72 (P < 0.05). Moreover, compared to pigs fed the C-SPC diet, pigs fed the C-SBM diet tended to have greater villus height (P = 0.092), while pigs fed the C-SPC + ISF diet had significantly greater villus height (P < 0.05); pigs fed the C-SBM and C-SPC + ISF diets had significantly increased villus height-to-crypt depth ratio (P < 0.05). Compared with the C-SPC diet, dietary C-SPC + ISF tended to increase plasma superoxide dismutase activity on days 28 (P = 0.085) and 42 (P = 0.075) and reduce plasma malondialdehyde (MDA) content on day 42 (P = 0.089), as well as significantly decreased jejunal mucosa MDA content on day 42 (P < 0.05). However, no significant difference in the expression of tight junction genes among the three groups was found (P > 0.05). In conclusion, our results suggest that a long-term exposure to soybean isoflavones enhances the growth performance, protects the intestinal morphology and improves the antioxidative properties in pigs.

Reconstructing the Perceived Faces from Brain Signals without Large Number of Training Samples. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020;2020:1108-1111. [PMID: 33018180 DOI: 10.1109/embc44109.2020.9176684]

Reconstructing the perceived faces from brain signals has become a promising work recently. However, the reconstruction accuracies rely on a large number of brain signals collected for training a stable reconstruction model, which is really time consuming, and greatly limits its application. In our current study, we develop a new framework that can efficiently perform high-quality face reconstruction with only a small number of brain signals as training samples. The framework consists of three mathematical models: principle component analysis (PCA), linear regression (LR) and conditional generative adversarial network (cGAN). We conducted a functional Magnetic Resonance Imaging (fMRI) experiment in which two subjects' brain signals were collected to test the efficiency of our proposed method. Results show that we can achieve state-of-the-art reconstruction performance from brain signals with a very limited number of fMRI training samples.

Exosomes from patients with major depression cause depressive-like behaviors in mice with involvement of miR-139-5p-regulated neurogenesis

Exosomal microRNAs (miRNAs) have been suggested to participate in the pathogenesis of neuropsychiatric diseases, but their role in major depressive disorder (MDD) is unknown. We performed a genome-wide miRNA expression profiling of blood-derived exosomes from MDD patients and control subjects and revealed the top differentially expressed exosomal miRNA, i.e. hsa-miR-139-5p (upregulation), had good performance to differentiate between MDD patients and controls. Tail vein injection of blood exosomes isolated from MDD patients into normal mice caused their depressive-like behaviors as determined by the forced swimming, tail suspension, and novelty suppressed feeding tests, and injection of blood exosomes isolated from healthy volunteers into unpredictable mild stress (CUMS)-treated mice alleviated their depressive-like behaviors. CUMS mice also showed significantly increased blood and brain levels of exosomal miR-139-5p. Furthermore, the depressive-like behaviors in CUMS-treated mice were rescued by intranasal injection of miR-139-5p antagomir, suggesting that increased exosomal miR-139-5p levels may mediate stress-induced depression-like behavior in mice. Both exosome treatment and miR-139-5p antagomir treatment increased hippocampal neurogenesis in the CUMS-treated mice, and treatment of exosome from MDD patients decreased hippocampal neurogenesis in the normal mice. The role of miR-139-5p in neurogenesis was validated by in vitro experiments, demonstrating that miR-139-5p is a negative regulator for neural stem cell proliferation and neuronal differentiation. Our findings together suggest that exosomes from patients with major depression caused depressive-like behaviors in mice with involvement of miR-139-5p-regulated neurogenesis. Therefore, exosomal miRNAs are promising targets for the diagnosis and treatment of MDD.

The Effect of Estrogen Replacement Therapy on Alzheimer's Disease and Parkinson's Disease in Postmenopausal Women: A Meta-Analysis

Background: Estrogen replacement therapy (ERT) is a common treatment method for menopausal syndrome; however, its therapeutic value for the treatment of neurological diseases is still unclear. Epidemiological studies were performed, and the effect of postmenopausal ERT on treating neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD), was summarized through a meta-analysis.

Methods: Twenty-one articles were selected using a systematic searching of the contents listed on PubMed and Web of Science before June 1, 2019. Epidemiological studies were extracted, and relevant research data were obtained from the original articles based on the predefined inclusion criteria and data screening principles. The Comprehensive Meta-Analysis Version 2 software was used to pool effective size, test heterogeneity, conduct meta-regression and subgroup analysis, and to calculate publication bias.

Results: Our results showed that ERT significantly decreased the risk of onset and/or development of AD [odds ratio (OR): 0.672; 95% CI: 0.581–0.779; P < 0.001] and PD (OR: 0.470; 95% CI: 0.368–0.600; P < 0.001) compared with the control group. A subgroup and meta-regression analysis showed that study design and measure of effect were the source of heterogeneity. Age, sample size, hormone therapy ascertainment, duration of the treatment, or route of administration did not play a significant role in affecting the outcome of the meta-analysis.

Conclusion: We presented evidence here to support the use of estrogen therapy for the treatment of AD and PD.

Hybridization Dynamics in CeCoIn_{5} Revealed by Ultrafast Optical Spectroscopy

We investigate the quasiparticle dynamics in the prototypical heavy fermion CeCoIn_{5} using ultrafast optical pump-probe spectroscopy. Our results indicate that this material system undergoes hybridization fluctuations before the establishment of heavy electron coherence, as the temperature decreases from ∼120  K (T^{†}) to ∼55  K (T^{*}). We reveal that the anomalous coherent phonon softening and damping reduction below T^{*} are directly associated with the emergence of collective hybridization. We also discover a distinct collective mode with an energy of ∼8  meV, which may be experimental evidence of the predicted unconventional density wave. Our findings provide important information for understanding the hybridization dynamics in heavy fermion systems.

Serum Exosome-Derived miR-139-5p as a Potential Biomarker for Major Depressive Disorder

BACKGROUND

MicroRNAs (miRs) have been suggested to be biomarkers to inform the diagnosis of major depressive disorder (MDD). We have previously shown that exosome-derived miR-139-5p had potential in differentiating between patients with MDD and healthy control (HC) subjects.

MATERIALS AND METHODS

To validate the potential of exosome-derived miR-139-5p as a biomarker for MDD, here we recruited 30 patients with MDD and 30 HC subjects, and used TaqMan probes to detect serum exosomal miR-139-5p levels.

RESULTS

The data showed that patients with MDD had significantly increased exosomal miR-139-5p levels when compared with controls. Correlation analysis suggested that sex, age, and body mass index did not significantly affect blood exosomal miR-139-5p levels in the tested subjects. The ROC curve showed that serum-derived miR-139-5p had reasonable performance in discriminating patients with MDD and HC subjects, with a sensitivity of 0.867 and specificity of 0.767, and the AUC was 0.807.

DISCUSSION

Taken together, these results demonstrated that patients with MDD were accompanied by significantly increased blood exosomal miR-139-5p levels, and exosomal miR-139-5p is a promising biomarker for the diagnosis of MDD.

Genome-Wide, Integrative Analysis Implicates Exosome-Derived MicroRNA Dysregulation in Schizophrenia

Genetic variants conferring risk for schizophrenia (SCZ) have been extensively studied, but the role of posttranscriptional mechanisms in SCZ is not well studied. Here we performed the first genome-wide microRNA (miRNA) expression profiling in serum-derived exosome from 49 first-episode, drug-free SCZ patients and 46 controls and identified miRNAs and co-regulated modules that were perturbed in SCZ. Putative targets of these SCZ-affected miRNAs were enriched strongly for genes that have been implicated in protein glycosylation and were also related to neurotransmitter receptor and dendrite (spine) development. We validated several differentially expressed blood exosomal miRNAs in 100 SCZ patients as compared with 100 controls by quantitative reverse transcription-polymerase chain reaction. The potential regulatory relationships between several SCZ-affected miRNAs and their putative target genes were also validated. These include hsa-miR-206, which is the most upregulated miRNA in the blood exosomes of SCZ patients and that previously reported to regulate brain-derived neurotrophic factor expression, which we showed reduced mRNA and protein levels in the blood of SCZ patients. In addition, we found 11 miRNAs in blood exosomes from the miRNA sequence data that can be used to classify samples from SCZ patients and control subjects with close to 90% accuracy in the training samples, and approximately 75% accuracy in the testing samples. Our findings support a role for exosomal miRNA dysregulation in SCZ pathophysiology and provide a rich data set and framework for future analyses of miRNAs in the disease, and our data also suggest that blood exosomal miRNAs are promising biomarkers for SCZ.

Serum Oxidative Stress Marker Levels in Unmedicated and Medicated Patients with Schizophrenia

Oxidative stress has been suggested to be involved in schizophrenia, but studies have demonstrated inconsistent results on oxidative stress marker level/activity in patients with schizophrenia. In order to clarify the circulating oxidative stress marker level/activity in patients with schizophrenia, this study recruited 80 schizophrenia patients (40 first-episode, drug-free and 40 chronically medicated patients) and 80 controls to analyze serum activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC), and levels of lipid peroxidation marker malondialdehyde (MDA) in schizophrenia patients, and whether they associate with the severity of the disease. We showed that only serum GSH-Px activity was significantly reduced in unmedicated patients with schizophrenia when compared with control subjects, whereas the other three analyzed oxidative stress markers did not show significant differences between cases and controls. Moreover, our results demonstrated that chronic medication increased GSH-Px activity and MDA levels in patients with schizophrenia, but reduced SOD activity in the patients. We also found that short-term antipsychotic treatments on the patients with schizophrenia reduced the SOD activity. Correlation analyses indicated that the oxidative stress marker activity/level is not significantly associated with the severity of schizophrenia, except that SOD level correlated with PANSS positive score significantly. Taken together, the data from the present study suggested that the dysfunctions of oxidative stress markers in patients with schizophrenia were mainly caused by antipsychotics, emphasizing increased oxidative stress as a potential side effect of antipsychotics on the patients.

Cloning and functional characterization of the HbSYR1 gene encoding a syntaxin-related protein in Tibetan hulless barley (Hordeum vulgare L. var. nudum HK. f.)

Tibetan barley is a staple food for the natives of Qinghai-Tibet Plateau. Drought causes a reduction in barley production. In this study, the full-length cDNA of a gene encoding a syntaxin-associated protein was cloned from the leaves of a drought-resistant variety of barley, "Himalaya 10"; its expression was evaluated during drought stress and rehydration via real-time PCR. The cloned HbSYR1 cDNA sequence was 1300 bp in length, and included an 840-bp open reading frame that encoded 279 amino acids. Sequence analysis predicted the molecular weight of the encoded protein to be 42.08 kDa, with an isoelectric point of 4.98. ScanProsite analysis showed that the HbSYR1 protein contained a SNARE family characteristic motif, five casein kinase II phosphorylation sites, two N-glycosylation sites, four protein kinase C phosphorylation sites, and two N-myristoylation sites. The TMHMM prediction program indicated that the protein does not contain a transmembrane transfer ribbon. According to the SignalP 3.0 server, this protein does not contain a signal peptide, and is not a secretory protein. Instead, this protein was suggested to be localized in the cytoplasm, as predicted by the protein subcellular localization prediction tool (PSORT). Our results indicated that HbSYR was induced by drought stress and rehydration, and was determined to be a key gene for drought resistance and water retention in barley.

NJ cluster analysis of the SnRK2, PYR/PYL/RCAR, and ABF genes in Tibetan hulless barley

The abscisic acid (ABA) signaling pathway is known as one of the most important signaling pathways in plants and is mediated by multiple regulators. The genes SnRK2, PYR/PYL/RCAR, and ABF are relevant to both ABA-dependent and -independent signaling pathways. To elucidate the profile of these genes from Tibetan hulless barley (Hordeum vulgare L. var. nudum Hook. f.), we collected available sequences from RNA-Seq data, together with NCBI data from five other model plant species (Arabidopsis thaliana, Brachypodium distachyon, Oryza sativa, Populus trichocarpa, and Sorghum bicolor). Gene trees of SnRK2, PYR/PYL/RCAR, and ABF were constructed using a neighbor joining (NJ) method. For all genes, we identified a dominant group in which all six species were represented. Three, four, and five groups were found in the NJ trees of SnRK2, PYR/PYL/RCAR, and ABF, respectively. For each gene, Tibetan hulless barley was divided into three groups. Our analyses indicated that Tibetan hulless barley was associated with B. distachyon. The NJ cluster analysis also suggested that Tibetan hulless barley was affiliated with S. bicolor (SnRK2), A. thaliana (PYR/PYL/RCAR), and O. sativa (ABF). These results illustrate a diverse expression of genes SnRK2, PYR/PYL/RCAR, and ABF, and suggest a relationship among the six species studied. Collectively, our characterization of the three components of the ABA signaling pathway may contribute to improve stress tolerance in Tibetan hulless barley.

Efficacy of intra-arterial neoadjuvant chemotherapy through the superior epigastric artery in the treatment of locally advanced triple negative breast cancer

Triple negative breast cancer (TNBC) is associated with aggressive behaviour and poor prognosis, but has limited treatment options. To explore novel and effective therapies against TNBC, we retrospectively analyzed the efficacy of neoadjuvant intra-arterial chemotherapy through the superior epigastric artery in the treatment of locally advanced TNBC. Fifty-one locally advanced TNBC patients who received this neoadjuvant therapy from Mar 2001 to Mar 2012 were included in this study. The superior epigastric artery was selected for cannulation to deliver chemotherapy drugs. The regimen for intra-arterial chemoinfusion consisted of 75 mg/m2 epirubicin and 75 mg/m2 docetaxel. Clinical and pathological tumor responses, disease free survival (DFS), overall survival (OS), and toxicity profiles were recorded and retrospectively analyzed. In 51 patients treated with neoadjuvant intra-arterial chemoinfusion through the superior epigastric artery, the overall response rate (ORR) was 84.3%; 16 patients achieved pathological complete response (pCR). Following surgical treatment and adjuvant chemotherapy, 5-year DFS and OS were 72.4% and 75.9%, respectively, in the study population. In addition, this neoadjuvant approach showed favorable toxicity profiles. Moreover, patients who achieved pCR showed a superior survival outcome compared with those who did not. Cox regression analysis indicated that Ki-67 expression is an independent predictor for DFS and OS. Our results suggest that intra-arterial chemotherapy through the superior epigastric artery has great therapeutic potential for the treatment of locally advanced TNBC. This approach merits further clinical evaluation and may become a novel therapeutic option for locally advanced TNBC.

[A 5 year surveillance of blindness in Yilong Commune, Yian County, Heilongjiang Province]

A sample of 35,404 people in Yilong Commune, Yian County, Heilongjiang Province, has been under surveillance since 1985 when the primary eye care system was established. In 1985, there were 52 blind people, representing a blindness prevalence of 0.15%; in 1990, the figure was reduced to 44, representing a prevalence of 0.12%. During the 5 years in between, the original 52 blind people were reduced by 15, while, from 22 cases of blinding eye diseases, 14 new cases of blindness arose, of whom 7 cases were cured. The incidence of blindness was 0.09/1000. The new cases of blindness were mainly elderly people and children, and the blinding diseases were glaucoma, cataract and congenital/hereditary diseases.

[The methodology and focus in blindness prevention from an epidemiologic point of view]

The present main causes of blindness in China are senile cataract, primary glaucoma' trachoma and corneal infections, and 80% of the blind are over 50 years of age, 75% become blind before 10 or after 50 years of age, and among 40% of the blind, the interval between visual loss in both eyes was over 1 year. The authors are of the opinion that the focus of efforts for blindness prevention should be directed to patients over 50 years of age, and particularly those of unilateral blindness, so as to prevent them from becoming bilaterally blind.