Use Of Cryoprotectants In Enhancing Viability Of Probiotic Lactobacillus Strains During Freeze-Drying And Storage

In recent years, probiotics have been considered to be used as feed supplements to improve the health and growth performance of poultry in place of antibiotic growth promoters. This is due to concerns that the rampant use of antibiotic growth promoters in livestock, particularly poultry, may produce adverse effects on humans, such as the development of antibiotic resistant bacteria and production of antibiotic residues in animal products. Unlike probiotics for humans, which are usually kept refrigerated, probiotics for poultry are normally kept in the farm at room temperature, and this may reduce the viability of the micro-organisms used in the probiotics during storage. Cryoprotectants incorporated during freeze drying of the probiotic could enhance the shelf-life of the probiotic micro-organisms. Thus, in this investigation, the main objective was to determine the best combination of cryoprotectants to enhance the viability of Lactobacillus brevis I25 and L. reuteri C10 during freeze-drying by using the response surface methodology (RSM). A five-level, three-variable central composite rotatable design (CCRD) was used to evaluate the interactive effects of skim milk, sucrose and lactose as cryoprotectants, on the viability of L. brevis I25 and L. reuteri C10 during freeze drying. The inputs, log cfu/ml, were derived experimentally and tested by RSM. The models were found to describe adequately the experimental range studied. The optimum combination of cryoprotectants derived via RSM analysis were: 8% skim milk, 22% sucrose, 0.5% lactose for L. brevis I25 and 19.5% skim milk, 1% sucrose, 9% lactose for L. reuteri C10. The actual experimental results on the viability of L. brevis I25 and L. reuteri C10 after freeze-drying were 8.88 and 8.83 log cfu/ml, respectively, under optimum formulation. These values were highly comparable to the predicted values by RSM method of SAS/STAT which were 8.82 log cfu/ml for L. brevis I25 and 8.89 log cfu/ml for L. reuteri C10. The log cfu/ml values for controls (freeze-dried without cryoprotectants) were 7.65 and 7.2 for L. brevis I25 and L. reuteri C10, respectively. During the six month storage study at 4oC and 30oC, the optimum cryoprotectant combination for L. brevis I25 had a very high survival rate at 4oC but not at 30oC. On the other hand, the survival rate of the best combination for L. reuteri C10 was very high at both temperatures during storage. There was 0% residual viability for control culture after 16 weeks of storage for L. brevis I25 at 4oC and after 4 weeks at 30oC. For L. reuteri C10 after 12 and 8 weeks no bacterial growth were detected at 4oC and 30oC, respectively. The organic acids and amylase activity of bacterial cultures were also analysed during storage. The results showed that during storage at 4oC, the acetic acid concentration decreased from 144 mM to 100.25 mM for L. brevis I25 and from 153 mM to 115.6 mM for L. reuteri C10. In the case of lactic acid, the concentration decreased from 294 mM to 215 mM for L. brevis I25 and 205 mM to 124 mM for L. reuteri C10. The concentration of succinic acid also decreased from 2.9 mM to 1.2 mM for L. brevis I25 and from 17 mM to 9.4 mM for L. reuteri C10. There was also a reduction in amylase activity from 0.2 U to 0.11 U for L. brevis I25 and from 0.34 U to 0.18 U for L. reuteri C10. Acid production and amylase activity patterns for both Lactobacillus strains correspond to the survival rate of the bacteria during storage at 30oC

Imaging Modalities Employed in Diabetic Retinopathy Screening: A Review and Meta-Analysis

Introduction: Urbanization has caused dramatic changes in lifestyle, and these rapid transitions have led to an increased risk of noncommunicable diseases, such as type 2 diabetes. In terms of cost-effectiveness, screening for diabetic retinopathy is a critical aspect in diabetes management. The aim of this study was to review the imaging modalities employed for retinal examination in diabetic retinopathy screening. Methods: The PubMed and Web of Science databases were the main sources used to investigate the medical literature. An extensive search was performed to identify relevant articles concerning “imaging”, “diabetic retinopathy” and “screening” up to 1 June 2021. Imaging techniques were divided into the following: (i) mydriatic fundus photography, (ii) non-mydriatic fundus photography, (iii) smartphone-based imaging, and (iv) ultrawide-field imaging. A meta-analysis was performed to analyze the performance and technical failure rate of each method. Results: The technical failure rates for mydriatic and non-mydriatic digital fundus photography, smartphone-based and ultrawide-field imaging were 3.4% (95% CI: 2.3–4.6%), 12.1% (95% CI: 5.4–18.7%), 5.3% (95% CI: 1.5–9.0%) and 2.2% (95% CI: 0.3–4.0%), respectively. The rate was significantly different between all analyzed techniques (p < 0.001), and the overall failure rate was 6.6% (4.9–8.3%; I2 = 97.2%). The publication bias factor for smartphone-based imaging was significantly higher than for mydriatic digital fundus photography and non-mydriatic digital fundus photography (b = −8.61, b = −2.59 and b = −7.03, respectively; p < 0.001). Ultrawide-field imaging studies were excluded from the final sensitivity/specificity analysis, as the total number of patients included was too small. Conclusions: Regardless of the type of the device used, retinal photographs should be taken on eyes with dilated pupils, unless contraindicated, as this setting decreases the rate of ungradable images. Smartphone-based and ultrawide-field imaging may become potential alternative methods for optimized DR screening; however, there is not yet enough evidence for these techniques to displace mydriatic fundus photography

Imaging Modalities Employed in Diabetic Retinopathy Screening: A Review and Meta-Analysis

Introduction: Urbanization has caused dramatic changes in lifestyle, and these rapid transitions have led to an increased risk of noncommunicable diseases, such as type 2 diabetes. In terms of cost-effectiveness, screening for diabetic retinopathy is a critical aspect in diabetes management. The aim of this study was to review the imaging modalities employed for retinal examination in diabetic retinopathy screening. Methods: The PubMed and Web of Science databases were the main sources used to investigate the medical literature. An extensive search was performed to identify relevant articles concerning “imaging”, “diabetic retinopathy” and “screening” up to 1 June 2021. Imaging techniques were divided into the following: (i) mydriatic fundus photography, (ii) non-mydriatic fundus photography, (iii) smartphone-based imaging, and (iv) ultrawide-field imaging. A meta-analysis was performed to analyze the performance and technical failure rate of each method. Results: The technical failure rates for mydriatic and non-mydriatic digital fundus photography, smartphone-based and ultrawide-field imaging were 3.4% (95% CI: 2.3–4.6%), 12.1% (95% CI: 5.4–18.7%), 5.3% (95% CI: 1.5–9.0%) and 2.2% (95% CI: 0.3–4.0%), respectively. The rate was significantly different between all analyzed techniques (p < 0.001), and the overall failure rate was 6.6% (4.9–8.3%; I2 = 97.2%). The publication bias factor for smartphone-based imaging was significantly higher than for mydriatic digital fundus photography and non-mydriatic digital fundus photography (b = −8.61, b = −2.59 and b = −7.03, respectively; p < 0.001). Ultrawide-field imaging studies were excluded from the final sensitivity/specificity analysis, as the total number of patients included was too small. Conclusions: Regardless of the type of the device used, retinal photographs should be taken on eyes with dilated pupils, unless contraindicated, as this setting decreases the rate of ungradable images. Smartphone-based and ultrawide-field imaging may become potential alternative methods for optimized DR screening; however, there is not yet enough evidence for these techniques to displace mydriatic fundus photography

Production of a Solvent, Detergent, and Thermotolerant Lipase by a Newly Isolated Acinetobacter sp. in Submerged and Solid-State Fermentations

The lipase production ability of a newly isolated Acinetobacter sp. in submerged (SmF) and solid-state (SSF) fermentations was evaluated. The results demonstrated this strain as one of the rare bacterium, which is able to grow and produce lipase in SSF even more than SmF. Coconut oil cake as a cheap agroindustrial residue was employed as the solid substrate. The lipase production was optimized in both media using artificial neural network. Multilayer normal and full feed forward backpropagation networks were selected to build predictive models to optimize the culture parameters for lipase production in SmF and SSF systems, respectively. The produced models for both systems showed high predictive accuracy where the obtained conditions were close together. The produced enzyme was characterized as a thermotolerant lipase, although the organism was mesophile. The optimum temperature for the enzyme activity was 45°C where 63% of its activity remained at 70°C after 2 h. This lipase remained active after 24 h in a broad range of pH (6–11). The lipase demonstrated strong solvent and detergent tolerance potentials. Therefore, this inexpensive lipase production for such a potent and industrially valuable lipase is promising and of considerable commercial interest for biotechnological applications

In situ bioconversion of coconut oil via coconut solid state fermentation by Geotrichum candidum ATCC 34614

Coconut base solid state fermentation was carried out by Geotrichum candidum ATCC 34614 for in situ coconut oil bioconversion. Coconut oil, which contains highly saturated medium chain triglycerides, was partially bioconverted into a combination of medium chain diglycerides, medium chain monoglycerides and medium chain fatty acids by this fungus lipolytic activity. The product demonstrated improved aroma, flavor, thermal behavior and antibacterial activity. Maximum triglycerides conversion (76.5 %) occurred at 40 % moisture content and 50 % oil content after 25 days of incubation. Bioconverted coconut oil revealed as much as 95 % antibacterial activity as well as altered thermal characteristic towards lower melting and higher crystallization points. The fermented culture also revealed highly fruity and flora notes which contained five main short- and medium-chain esters known as aromatic compounds. The present study established the possibility of using G. candidum ATCC 34614 in coconut solid culture for bioconversion of coconut oil, which improves the fermented product characteristics

Comparison Study of the Two Biometers Based on Swept-Source Optical Coherence Tomography Technology

This research aimed to investigate the potential differences in the parameters, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), flat keratometry (Kf), steep keratometry (Ks), mean keratometry (Km), astigmatism, white-to-white (WTW) distance, acquired rate, and intraocular lens (TOL) power, between the two swept-source optical coherence tomography (SS-OCT) biometers, the ANTERION (biometer A) and IOLMaster 700 (biometer B). In a prospective observational comparative case series study, we enrolled 198 eyes undergoing cataract surgery. The AL, CCT, ACD, LT, Kf, Ks, Km, astigmatism, WTW, acquired rate, and IOL power were assessed. McNemar tests compared the acquired rate, and the paired sample t-test compared the quantitative measurement results between the groups. Nineteen eyes were excluded owing to missing AL data for either biometer. Finally, data from 179 eyes were analyzed. Between the two devices, no significant difference was found in AL, astigmatism magnitude, J0, and J45, while significant differences existed in CCT, ACD, LT, Kf, Ks, Km, WTW, astigmatism axis, and IOL power; no statistical significance was found in the AL acquired rate (biometer A, 90.9% and biometer B, 93.9%). Approximately 65.4% of eyes demonstrated >= 0.5-D difference in IOL power between the two biometers. In conclusion, the two biometers showed significant differences in all measurements (CCT, ACD, LT, K, WTW, astigmatism axis, and IOL power), except for AL.Peer reviewe

Semi‐Automated Quantification of Retinal and Choroidal Biomarkers in Retinal Vascular Diseases: Agreement of Spectral‐Domain Optical Coherence Tomography with and without Enhanced Depth Imaging Mode

Background: We compared with and without enhanced depth imaging mode (EDI) in semi-automated quantification of retinal and choroidal biomarkers in optical coherence tomography (OCT) in patients with diabetic retinopathy (DR) or retinal vein occlusion (RVO) complicated by macular edema. We chose to study three OCT biomarkers: the numbers of hyperreflective foci (HF), the ellipsoid zone reflectivity ratio (EZR) and the choroidal vascularity index (CVI), all known to be correlated with visual acuity changes or treatment outcomes. Methods: In a single examination, one eye of each patient (n = 60; diabetic retinopathy: n = 27, retinal vein occlusion: n = 33) underwent macular 870 nm spectral domain-OCT (SD-OCT) B-scans without and with EDI mode. Semi-automated quantification of HF, EZR and CVI was applied according to preexisting published protocols. Paired Student’s t-test or Wilcoxon rank-sum test was used to test for differences in subgroups. Intraclass correlation coefficient (ICC) and Bland–Altman plots were applied to describe the agreement between quantification in EDI and conventional OCT mode. The effect of macular edema on semi-automated quantification was evaluated. Results: For the entire cohort, quantification of all three biomarkers was not significantly different in SD-OCT scans with and without EDI mode (p > 0.05). ICC was 0.78, 0.90 and 0.80 for HF, EZR and CVI. The presence of macular edema led to significant differences in the quantification of hyperreflective foci (without EDI: 80.00 ± 33.70, with EDI: 92.08 ± 38.11; mean difference: 12.09, p = 0.03), but not in the quantification of EZR and CVI (p > 0.05). Conclusion: Quantification of EZR and CVI was comparable whether or not EDI mode was used. In conclusion, both retinal and choroidal biomarkers can be quantified from one single 870 nm SD-OCT EDI image

Investigation on Non-Segmentation Based Algorithms for Microvasculature Quantification in OCTA Images

Optical Coherence Tomography Angiography (OCTA) is an imaging modality that provides three-dimensional information of the retinal microvasculature and therefore promises early diagnosis and sufficient monitoring in ophthalmology. However, there is considerable variability between experts analysing this data. Measures for quantitative assessment of the vasculature need to be developed and established, such as fractal dimension. Fractal dimension can be used to assess the complexity of vessels and has been shown to be independently associated with neovascularization, a symptom of diseases such as diabetic retinopathy. This investigation assessed the performance of three fractal dimension algorithms: Box Counting Dimension (BCD), Information Dimension (ID), and Differential Box Counting (DBC). Two of those, BCD and ID, rely on previous vessel segmentation. Assessment of the added value or disturbance regarding the segmentation step is a second aim of this study. The investigation was performed on a data set composed of 9 in vivo human eyes. Since there is no ground truth available, the performance of the methods in differentiating the Superficial Vascular Complex (SVC) and Deep Vascular Complex (DVC) layers apart and the consistency of measurements of the same layer at different time-points were tested. The performance parameters were the ICC and the Mann-Whitney U tests. The three applied methods were suitable to tell the different layers apart and showed consistent values applied in the same slab. Within the consistency test, the non-segmentation-based method, DBC, was found to be less accurate, expressed in a lower ICC value, compared to its segmentation-based counterparts. This result is thought to be due to the DBC’s higher sensitivity when compared to the other methods. This higher sensitivity might help detect changes in the microvasculature, like neovascularization, but is also more likely prone to noise and artefacts

Comparison of Mean Corneal Power of Annular Rings and Zones Using Swept-Source Optical Coherence Tomography

This study aims to investigate differences in the mean corneal power of annular zones (corneal power measured over the inner annular zone of difference diameters) and rings (corneal power measured over a ring of different diameters) centered on the corneal apex using the swept-source optical coherence tomography technique. The mean anterior axial curvature (AAC), posterior axial curvature (PAC), and total corneal power (TCP) centered on the corneal apex with the annular rings (0-2 mm, 2-4 mm, 4-6 mm, and 6-8 mm) and zones were assessed using the ANTERION device. The paired-sample t-test was used for data comparison. For the 0-2 mm comparison, the AAC, PAC, and TCP values of rings and zones were interchangeable. For the 2-4 mm comparison, the AAC of the rings was lower than that of the zones (p = 0.004), and the TCP values of the rings were higher than that of the zones (p < 0.001). For the 4-6 mm comparison, the AAC of the rings was lower than that of the zones (p < 0.001), and the PAC and TCP values of the rings were higher than that of the zones (both p < 0.001). For the 6-8 mm comparison, the AAC of the rings was lower than that of the zones (p < 0.001), and the PAC and TCP values of the rings were higher than that of the zones (both p < 0.001). Comparisons between AAC and TCP in each sub-region showed significant differences both in the rings (p < 0.001) and the zones (p < 0.008). Differences in the AAC, PAC, and TCP measured at different diameters (2-4 mm, 4-6 mm, and 6-8 mm) of the rings and zones, centered on the corneal apex, should be noticed in clinical practice. As the diameter increases, the difference between the rings and the zones in terms of AAC, PAC, and TCP increase as well. Clinicians should also pay attention to differences between AAC and TCP for the rings and the zones within the same annular region.Peer reviewe