[Using artificial intelligence as an initial triage strategy in diabetic retinopathy screening program in China]

Objective: To investigate the diagnostic accuracy and efficiency of an artificial intelligence (AI) triaging model in a diabetic retinopathy (DR) screening program. Methods: A DR screening program was conducted in Kashi City and Kizilsu Kirghiz Autonomous Prefecture of the Xinjiang Uyur Autonomous Region from May to July 2018, and 8 005 patients with diabetes mellitus were included. Fundus images, one centered at optic disc and one centered at macula, were taken for both eyes. A previously validated AI algorithm was applied as the first step to identify the patients with all 4 images. If the images were classified as gradable and negative DR, an AI-generated report was immediately provided without sending to manual grading, and 1/3 of these patients were randomly sampled for manual grading and quality control (group A). For the patients with at least one image classified as ungradable or positive for any DR, all images were sent for manual grading (group B). Finally, 300 patients were randomly selected from group A and group B respectively for accuracy assessment, where the patients and their images were classified by a specialist panel for referral DR (pre-proliferative DR, or proliferative DR, and/or diabetic macular edema). Results: Among 8 005 patients for DR screening [including 3 220 males and 4 785 females, aged (58.3±10.6) years], after AI triaging, 5 267 (65.8%) potentially received reports from AI system and 2 738 (34.2%) required manual grading. In group A, the accuracy and specificity of AI classification and manual grading on referral DR were all 100%. In group B, the accuracy of AI and manual grading were 75.8% and 90.3%, respectively, while the sensitivity of AI and manual grading was 100% and 79.1%, respectively. Conclusion: AI alleviates 60% of the workload of manual grading without missing any referral patients with the aid of the current AI triaging model.

Many Analysts, One Data Set: Making Transparent How Variations in Analytic Choices Affect Results

Twenty-nine teams involving 61 analysts used the same data set to address the same research question: whether soccer referees are more likely to give red cards to dark-skin-toned players than to light-skin-toned players. Analytic approaches varied widely across the teams, and the estimated effect sizes ranged from 0.89 to 2.93 ( Mdn = 1.31) in odds-ratio units. Twenty teams (69%) found a statistically significant positive effect, and 9 teams (31%) did not observe a significant relationship. Overall, the 29 different analyses used 21 unique combinations of covariates. Neither analysts’ prior beliefs about the effect of interest nor their level of expertise readily explained the variation in the outcomes of the analyses. Peer ratings of the quality of the analyses also did not account for the variability. These findings suggest that significant variation in the results of analyses of complex data may be difficult to avoid, even by experts with honest intentions. Crowdsourcing data analysis, a strategy in which numerous research teams are recruited to simultaneously investigate the same research question, makes transparent how defensible, yet subjective, analytic choices influence research results.

Antibacterial polyurethane nanocomposites using chlorhexidine diacetate as an organic modifier

Polymer nanocomposites (NCs) are hypothesised to have enhanced barrier properties compared with pristine polymer, allowing more sustained drug release from the materials. In these NC systems active agents are typically incorporated into the polymer matrix and the release kinetics are theoretically perturbed by well dispersed nanoparticle inclusions. An alternative approach is to exploit active agent interactions with the nanoinclusion. In the proposed NC system, the driving hypothesis is that active agents can have dual functionality, acting as both drug and dispersant. Polyurethane-montmorillonite (PEU-MMT) NCs were prepared in which the antimicrobial agent chlorhexidine diacetate (CHX) was evaluated as an organic modifier for silicate dispersion. CHX was incorporated at various concentrations through organic modification of MMT or within the bulk polymer. X-ray diffraction and transmission electron microscopy analysis suggested that intercalated and partially exfoliated NCs were achieved, with better dispersion occurring in the presence of free CHX within the bulk. Tensile testing results showed that variations in the level of organic modification and nanoparticle loading modulated the mechanical properties. Material stiffness increased with nanoparticle loading relative to pristine PEU, and the ultimate properties decreased with nanoparticle and free CHX incorporation. Antibacterial activity against Staphylococcus epidermidis was significant in materials with higher exchanged MMT and NCs containing free CHX, for which 2-log reductions in adherent bacteria were found after 24h. CHX was successfully used to modulate the material properties in its dual role as a dispersant and antimicrobial agent, suggesting that alternative biocides of similar structure may behave comparably within PEU-MMT NC systems.

The reuse of treated wastewater for agricultural purposes in Nicaragua; Central America

The first subsurface flow wetland (SSFW) system for about 1,000 PE, was constructed in Nicaragua in 1996 to apply this technology in the form of an integral project, combining the treatment of domestic wastewater with its reuse for crop production in small and medium size communities. The SSFW-effluent meets all standards established in the national regulations for wastewater reuse in agriculture, except for faecal coliforms, existent at an average concentration of 7 x 10(4) MPN/100 ml. A conventional surface irrigation method was used to irrigate different crop species selected to establish their risk of contamination. To judge the potential health risk for consumers and farmers, samples of vegetables and fruits harvested in the dry seasons of the years 1997 to 2002, were analyzed for the presence of pathogenic microorganisms like faecal coliforms, salmonella and shigella. In addition, a yield comparison between crops irrigated with well water using chemical fertilizers, and crops irrigated with the effluent of the SSFW-system was made, to analyze the economical benefits of the wastewater reuse.

Capping, splicing, and 3' processing are independently stimulated by RNA polymerase II: different functions for different segments of the CTD

Capping, splicing, and cleavage/polyadenylation of pre-mRNAs are interdependent events that are all stimulated in vivo by the carboxy-terminal domain (CTD) of RNA Pol II. We show that the CTD independently enhances splicing and 3' processing and that stimulation of splicing by enhancers is facilitated by the CTD. We provide evidence that stimulation of 3' processing by the CTD requires contact with the 50-kD subunit of the cleavage stimulation factor, CstF. Overexpression of the CTD-binding domain of CstF p50 had a dominant-negative effect on 3' processing without disrupting the CstF complex. The CTD comprises 52 heptad repeats. The CTD carboxyl terminus including heptads 27-52 supported capping, splicing, and 3' processing but the amino terminus supported only capping. We conclude that the CTD independently stimulates all three major pre-mRNA processing steps and that different regions of the CTD can serve distinct functions in pre-mRNA processing.

The association of bone mineral density with vitamin D receptor gene polymorphisms

A recent meta-analysis of 16 publications suggested that bone mineral density (BMD) is not associated with vitamin D receptor (VDR) gene polymorphism (VDRGP) at the 0.05 significance level when a study with genotyping mistakes is excluded. We wished to determine whether 'positive' findings supporting the BMD-VDRGP association may be explained by chance, and what factors affect the outcomes of these studies. Seventy-five articles and abstracts on the association of VDRGP with BMD and related skeletal phenotypes published before January 1997 were identified. Twenty-three of 67 (34.3%) studies on spinal BMD and 22 of 51 (43.1%) on femoral neck BMD had found a BMD-VDRGP association at p < 0.05, significantly (p = 7 x 10(-14) for spinal BMD, p = 9 x 10(-16) for hip BMD) higher than the expected 5% false positive rate under the null hypothesis of 'no association'. 'Positive' results were more frequently observed in studies on females before the menopause than those on females after the menopause (p < 0.02) or on male and female subjects combined (p < 0.05) when skeletal phenotypes at any bone sites were considered. The 'positive rate' among studies was also influenced by the age range of subjects studied and by the inclusion of subjects with osteoporosis. It is concluded that: (1) BMD is associated with VDRGP with high levels of confidence and (2) non-genetic factors and genetic heterogeneity interfere with the detection of the effects of VDRGP on bone phenotypes.

5'-Capping enzymes are targeted to pre-mRNA by binding to the phosphorylated carboxy-terminal domain of RNA polymerase II

We have investigated the role of the RNA Polymerase II (Pol II) carboxy-terminal domain (CTD) in mRNA 5' capping. Transcripts made in vivo by Pol II with a truncated CTD had a lower proportion of capped 5' ends than those made by Pol II with a full-length CTD. In addition, the enzymes responsible for cap synthesis, RNA guanylyltransferase, and RNA (guanine-7)-methyltransferase bound directly to the phosphorylated, but not to the nonphosphorylated, form of the CTD in vitro. These results suggest that: (1) Pol II-specific capping of nascent transcripts in vivo is enhanced by recruitment of the capping enzymes to the CTD and (2) capping is co-ordinated with CTD phosphorylation.

The C-terminal domain of RNA polymerase II couples mRNA processing to transcription

Messenger RNA is produced by RNA polymerase II (pol II) transcription, followed by processing of the primary transcript. Transcription, splicing and cleavage-polyadenylation can occur independently in vitro, but we demonstrate here that these processes are intimately linked in vivo. We show that the carboxy-terminal domain (CTD) of the pol II large subunit is required for efficient RNA processing. Splicing, processing of the 3' end and termination of transcription downstream of the poly(A) site, are all inhibited by truncation of the CTD. We found that the cleavage-polyadenylation factors CPSF and CstF specifically bound to CTD affinity columns and copurified with pol II in a high-molecular-mass complex. Our demonstration of an association between the CTD and 3'-processing factors, considered together with reports of a similar interaction with splicing factors, suggests that an mRNA 'factory' exists which carries out coupled transcription, splicing and cleavage-polyadenylation of mRNA precursors.

A survey of the feline leukaemia virus in Singapore

In this survey for the presence of the feline leukaemia virus (FeLV) in the Singapore domestic cat population, the sera of two different groups of unvaccinated mainly short haired cats which were over 6 months old were sampled. The FeLV enzyme-linked immunoadsorbent assay (ELISA) diagnostic test kit was used to detect the presence of the FeLV group specific (gs) antigens in the blood of cats. Of the 345 clinically healthy cats surveyed, 34 sera (9.9%) were found to be positive and of the group of 123 cats with clinical signs such as chronic wasting, marked by anaemia, anorexia and lethargy, 33 sera (26.8%) were found to be positive. From the time of diagnosis of a viraemia, 70% of cats will die within 20 months. The results are therefore indicative that annually a small proportion of cats in the local environment will die from a FeLV infection. This survey reflects the natural distribution of an infectious oncovirus in a susceptible host population which is unaffected by any control programme to interfere with the normal sequence of events of host virus interactions.

Decreased formation of aqueous humour in insulin-dependent diabetic patients

The rate of aqueous humour formation was measured by fluorophotometry in 34 insulin-dependent diabetic patients and 12 non-diabetic controls to determine whether or not aqueous flow in diabetics differed from that of normal controls, and whether or not aqueous flow among diabetics was correlated with the stage of retinopathy. Diabetic patients were divided into three groups based on the degree of retinopathy; group I without retinopathy, group II with minimal to moderate non-proliferative retinopathy, and group III with proliferative retinopathy. Aqueous flow (mean, SD) in diabetic patients was: 1.55 (0.32) microliter/min in group I, 1.51 (0.47) microliter/min in group II, and 1.26 (0.39) microliter/min in group III. No statistically significant difference was found among these three diabetic groups. Aqueous flow in the non-diabetic controls was 2.18 (0.40) microliter/min, and this was statistically significantly greater than in each of the diabetic groups. Intraocular pressure, age, duration of diabetes, haemoglobin A1C, and blood glucose levels had no significant effect on aqueous flow in diabetic patients.

Expression of three recombinant homodimeric isoforms of PDGF in Saccharomyces cerevisiae: evidence for difference in receptor binding and functional activities

Three recombinant homodimeric isoforms of platelet-derived growth factor (PDGF) were produced and purified in milligram quantities by expression of PDGF A- and B-chains in yeast cells. Structural analysis of the purified short and long variants of PDGF-AA (PDGF-AAS and PDGF-AAL) and PDGF-BB showed that they had been properly processed and assembled into dimers. PDGF-AAS and PDGF-AAL were found to bind only to the PDGF A-type receptor on human fibroblasts, with affinities of 0.1 and 0.2 nM, respectively. PDGF-BB bound to cells with A- and B-type receptors and to cells with B-type receptor only with affinities of 0.6 nM in both cases. Each fibroblast appeared to express about 4-5 times more B-type receptors than A-type receptors. The maximal mitogenic response to PDGF-BB of human fibroblasts was almost 2-fold higher than that induced by either of the two PDGF-AA forms. The three isoforms of PDGF also stimulated growth in soft agar of human fibroblasts with PDGF-BB inducing a higher maximal response.

Structure of a mouse submaxillary messenger RNA encoding epidermal growth factor and seven related proteins

The structure of the messenger RNA (mRNA) encoding the precursor to mouse submaxillary epidermal growth factor (EGF) was determined from the sequence of a set of overlapping complementary DNA's (cDNA). The mRNA is unexpectedly large, about 4750 nucleotide bases, and predicts the sequence of preproEGF, a protein of 1217 amino acids (133,000 molecular weight). The EGF moiety (53 amino acids) is flanked by polypeptide segments of 976 and 188 amino acids at its amino and carboyxl termini, respectively. The amino terminal segment of the precursor contains seven peptides with sequences that are similar but not identical to EGF.