Macular density alterations in myopic choroidal neovascularization and the effect of anti-VEGF on it.

AIM: To analyse macular microvascular alterations in myopic choroidal neovascularization (mCNV) and the efficiency of anti-vascular endothelial growth factor (anti-VEGF) therapy for mCNV by optical coherence tomography angiography (OCTA). METHODS: A total of 123 patients were included in this retrospective study, divided into mCNV group, high myopia (HM) group, and normal group at the Affiliated Eye Hospital of Wenzhou Medical University from January 2017 to January 2019. Superficial vessel density, deep capillary density, foveal avascular zone (FAZ) area, A-circularity index (AI) and vessel density around the 300 µm width of the FAZ region density (FD) and the area of choroidal neovascularization (CNV) lesion (only for mCNV group) were measured on 3×3 mm2 OCTA images. FAZ area was corrected for axial length. Central macular thickness (CMT) was measured on OCT in mCNV group. Compared the parameters on OCTA of 3 groups and pre-anti-VEGF and post-anti-VEGF at 1, 2, 3, and 6mo follow-up in mCNV group. RESULTS: There were significant differences among 3 groups in superficial vessel density, deep capillary density and FD (P<0.05). FAZ area in HM group was smaller than normal group (P<0.05), but there was no significant difference between mCNV group and the other two group. AI increased in mCNV group (P<0.05). The mean CMT, area and flow area of CNV lesion decreased after treatment (P<0.05), while vessel density and FAZ didn't change. The mean CMT, area and flow area of CNV lesion statistically decreased after anti-VEGF treatment in mCNV group (P<0.05), while superficial vessel density, deep capillary density and FAZ area, AI and FD didn't change. The mean reduction ratio of lesions was 50.32% (7.07% to 100%). Lesion regression 100% was observed in 2 cases (4.88%). There was a negative correlation between the CNV lesion area and reduction ratio (r=-0.380, P=0.042) and the flow lesion area and reduction ratio (r=-0.402, P=0.030). CONCLUSION: Macular vessel density decreases, FAZ turns smaller and more irregular in mCNV eyes. Anti-VEGF therapy is efficient for mCNV without affecting vessel density and FAZ, but it is unable to completely eliminate CNV lesions in most cases. The bigger mCNV lesions have lower reduction ratio.

Comprehensive evaluation of intravitreal conbercept versus half-dose photodynamic therapy for chronic central serous chorioretinopathy.

AIM: To compare the safety and efficacy of conbercept intravitreal injection and half-dose photodynamic therapy (PDT) in treating chronic central serous chorioretinopathy (CSC). METHODS: This study was retrospective. Thirty-seven patients (37 eyes) with chronic CSC received conbercept injections while 57 patients (57 eyes) were treated with half-dose PDT. All subjects were followed in 6mo. Outcome measures included change in best-corrected visual acuity (BCVA), central macular thickness (CMT), subfoveal choroidal thickness (SFCT), and resolution of subretinal fluid (SRF). RESULTS: There was no adverse event observed in either treatment group. At the 6-month follow-up, 26 eyes (70.3%) in the conbercept group and 54 eyes (94.7%) in the half-dose PDT group (P<0.05) reached full resolution of SRF. The mean logarithm of the minimum angle of resolution (logMAR) BCVA significantly improved (P<0.001) in both treatment groups with better outcome at early phase in the half-dose PDT group (2wk, 1, and 2mo, P<0.05). All subjects experienced significant CMT improvement (P<0.001) with no statistical difference between the two groups (P>0.05). The SFCT also improved in all subjects (P<0.001) with better outcome in the half-dose PDT group (P<0.05). CONCLUSION: Both intravitreal conbercept and half-dose PDT are safe to use in treating chronic CSC. By 6mo, both treatment groups are efficacious in improving BCVA, reducing CMT and SFCT, and resolving SRF in eyes with chronic CSC. Half-dose PDT may show better outcome at initial phase of treatment in chronic CSC. Longer follow-up period is necessary to study for long-term effect and safety.

An embedded system for the automated generation of labeled plant images to enable machine learning applications in agriculture.

A lack of sufficient training data, both in terms of variety and quantity, is often the bottleneck in the development of machine learning (ML) applications in any domain. For agricultural applications, ML-based models designed to perform tasks such as autonomous plant classification will typically be coupled to just one or perhaps a few plant species. As a consequence, each crop-specific task is very likely to require its own specialized training data, and the question of how to serve this need for data now often overshadows the more routine exercise of actually training such models. To tackle this problem, we have developed an embedded robotic system to automatically generate and label large datasets of plant images for ML applications in agriculture. The system can image plants from virtually any angle, thereby ensuring a wide variety of data; and with an imaging rate of up to one image per second, it can produce lableled datasets on the scale of thousands to tens of thousands of images per day. As such, this system offers an important alternative to time- and cost-intensive methods of manual generation and labeling. Furthermore, the use of a uniform background made of blue keying fabric enables additional image processing techniques such as background replacement and image segementation. It also helps in the training process, essentially forcing the model to focus on the plant features and eliminating random correlations. To demonstrate the capabilities of our system, we generated a dataset of over 34,000 labeled images, with which we trained an ML-model to distinguish grasses from non-grasses in test data from a variety of sources. We now plan to generate much larger datasets of Canadian crop plants and weeds that will be made publicly available in the hope of further enabling ML applications in the agriculture sector.

Improved event positioning in a gamma ray detector using an iterative position-weighted centre-of-gravity algorithm.

An iterative position-weighted centre-of-gravity algorithm was developed and tested for positioning events in a silicon photomultiplier (SiPM)-based scintillation detector for positron emission tomography. The algorithm used a Gaussian-based weighting function centred at the current estimate of the event location. The algorithm was applied to the signals from a 4 × 4 array of SiPM detectors that used individual channel readout and a LYSO:Ce scintillator array. Three scintillator array configurations were tested: single layer with 3.17 mm crystal pitch, matched to the SiPM size; single layer with 1.5 mm crystal pitch; and dual layer with 1.67 mm crystal pitch and a ½ crystal offset in the X and Y directions between the two layers. The flood histograms generated by this algorithm were shown to be superior to those generated by the standard centre of gravity. The width of the Gaussian weighting function of the algorithm was optimized for different scintillator array setups. The optimal width of the Gaussian curve was found to depend on the amount of light spread. The algorithm required less than 20 iterations to calculate the position of an event. The rapid convergence of this algorithm will readily allow for implementation on a front-end detector processing field programmable gate array for use in improved real-time event positioning and identification.

Gene cassette arrays, antibiotic susceptibilities, and clinical characteristics of Acinetobacter baumannii bacteremic strains harboring class 1 integrons.

BACKGROUND AND PURPOSE: Acinetobacter baumannii isolates containing class 1 integrons belong to different clones, but only a few strains are successful at causing infection. This study was conducted to compare the characteristics among these clones with different epidemicity. METHODS: Eighty eight bacteremic isolates of A. baumannii were collected in a medical center in Taiwan during a 3-year period. The gene cassettes and antibiotic susceptibilities of the bacterial isolates were delineated and the patients' characteristics were compared. RESULTS: Class 1 integrons were detected in 75 isolates (85.2%). Most of the isolates belonged to 2 major clones, but only 1 of the 2 clones caused outbreaks in several hospitals in Taiwan. Restriction analyses of variable regions of the integron revealed identical gene cassettes among isolates within the same clone. The cassette arrays of the 3 clones were aacA4, catB8, aadA1 (clone I, epidemic clone); dhfr XII, unknown open reading frame (orfF), aadA2 (clone II, endemic clone); and aacC1, 2 unknown open reading frames (orfX, orfX'), aadA1a (clone III). The epidemic and endemic strains were multidrug resistant, but the former presented a higher resistance rate to ampicillin-sulbactam. Infections with epidemic strains were significantly associated with prior use of cephalosporins, but didn't contribute to a higher mortality rate. CONCLUSIONS: Judicious use of cephalosporins and rapid identification using the integron typing method might be helpful for the prevention of further spread of strains with epidemic potential.

Non-typhoidal Salmonella bacteremia in adults.

BACKGROUND AND PURPOSE: Very few studies have examined prognostic factors in adult patients with non-typhoidal Salmonella (NTS) bacteremia. The purpose of this study was to identify the prognostic factors of these patients. METHODS: A total of 79 episodes of NTS bacteremia were identified in 73 patients between January 2001 and December 2003. Susceptibilities to various antimicrobials were determined using disk-diffusion tests and National Committee for Clinical Laboratory Standards criteria. Multiple logistic regression was used to evaluate the relationship between patients' characteristics and covariates of mortality. RESULTS: There were only 5 episodes (6%) of gastroenteritis, two of which were due to Salmonella septicemia contracted abroad. Potentially predisposing factors were identifiable in 51 episodes (65%). Infections in 24 patients (30%) were due to serogroup B Salmonella and in 22 patients (28%), to serogroup C Salmonella. A logistic regression analysis selected two variables as independently influencing prognosis: coma (p=0.006) and septic shock (p=0.002). CONCLUSIONS: Thus, most adult patients with NTS bacteremia do not develop gastroenteritis. Patients in shock or coma have poor prognosis, and susceptibility to third-generation cephalosporins, cefepime, and carbapenem is high.

Risk factors for central venous catheter-related infections in general surgery.

BACKGROUND AND PURPOSE: Central venous catheter (CVC) infection is a common problem during hospitalization and nosocomial bloodstream infection in these patients is associated with increased morbidity, mortality, and health care cost. This prospective study examined the risk factors of CVC-related infections. METHODS: During a 6-month period, a total of 281 patients who underwent central venous catheterization after general surgery were enrolled. RESULTS: The mean duration from CVC insertion to the development of infection was 7.12 days. The rate of bloodstream infection without isolation of the same organism from the catheter was 1.4% (4/281). The rate of catheter-related bloodstream infection was 6.0% (17/281). The rate of catheter bacteremia, defined as positive culture from a catheter blood sample in a patient without signs of infection, was 8.5% (24/281). The incidence of catheter-related bloodstream infection was 7.5/1000 catheter-days. Risk factors for catheter-related infection on univariate analysis included place of insertion (operating room or surgical ward), total parenteral nutrition (TPN), more than 3 tubings, and duration of catheterization. TPN was a significant risk factor in the logistic regression analysis. CONCLUSIONS: Established infection control guidelines should be rigorously observed with regard to catheter use and various risk factors controlled to prevent the occurrence of CVC-related infection, especially in patients receiving TPN.

Clinical characteristics and risk factors for attributable mortality in Enterobacter cloacae bacteremia.

BACKGROUND AND PURPOSE: Enterobacter spp. have emerged as an important cause of nosocomial bacteremia. The purpose of this study was to delineate the clinical, laboratory and microbiologic features that may influence prognosis of Enterobacter cloacae and enable a stratification of those patients at high risk of mortality. METHODS: This retrospective study reviewed 108 episodes of E. cloacae bacteremia occurring over a 2-year period (November 2001 to October 2003) at Taipei Veterans General Hospital. Univariate analysis were performed to demonstrate the relation of possible risk factors to death attributable to E. cloacae bacteremia. RESULTS: Ninety-three episodes (86.1%) were hospital-acquired. The most common portal of entry was the genitourinary tract (17.9%) followed by the gastrointestinal tract (15.1%). Underlying diseases associated with E. cloacae bacteremia were neoplastic diseases (42 episodes, 38.9%), diabetes mellitus (20 episodes, 18.5%) and chronic renal failure (18 episodes, 16.7%). The overall mortality rate was 42.6%, and E. cloacae bacteremia-attributable mortality occurred in 22 patients (20.9%). Factors significantly correlated with death attributable to bacteremia were older age, a higher medium number of underlying diseases, hemoglobin <10 g/dL, serum C-reactive protein >10 mg/dL, hypoalbuminemia, disseminated intravascular coagulation, septic shock, respiratory failure, renal failure (creatinine >2 mg/dL) and delayed clinical response after initiation of antibiotic therapy. CONCLUSIONS: Antibiotic-resistant isolates and appropriate empirical antibiotic use were not independent predictors of mortality in this study. The condition of patients at onset of symptoms and presence of underlying diseases appear to be important predictors mortality from E. cloacae bacteremia.