Supplementation of coated sodium butyrate relieved weaning stress and reshaped microbial flora in weaned lambs.

Weaning is an important period in the growth and development of lambs. Thus, effectively reducing the occurrence of weaning stress is critical for maintaining lamb production. Coated sodium butyrate has been shown to reduce inflammation, promote intestinal health, and maintain homeostasis. However, the application and potential mechanism of coated sodium butyrate in alleviating weaning stress in lambs are still unclear. To evaluate the effects of coated sodium butyrate on the growth performance, antioxidant capacity, and gut microbiota of weaned lambs, 10 weaned lambs of 21-day-old were randomly divided into two groups: the CON group (basal diet) and the NaB group (basal diet +3 g/kg of coated sodium butyrate). The trial lasted 21 days. The experimental results showed that compared to the CON group, coated sodium butyrate supplementation in the diet significantly increased the average daily weight gain and daily feed intake of lambs (p < 0.05). In addition, compared to the CON group, the addition of coated sodium butyrate also significantly decreased the serum MDA level of lambs (p < 0.05). Notably, the addition of coated sodium butyrate did not have a significant effect on the cecal microbiota, while increasing the diversity of colonic microbiota and promoting the abundance of Lachnospiraceae, Verrucomicrobiota, Akkermansia, Roseburia, and Sinobacteraceae, which are associated with the nutrient absorption of lambs (p < 0.05). These results indicate that dietary supplementation with coated sodium butyrate could promote the growth and antioxidant capacity of weaned lambs and alleviate weaning stress.

Exploring Cr(VI)-induced blood-brain barrier injury and neurotoxicity in zebrafish and snakehead fish, and inhibiting toxic effects of astaxanthin.

Cr(VI) is a common hazardous heavy metal contaminant that seriously endangers human and aquatic animal health. GPX4 was the key enzyme that reduces heavy metal toxicity through inhibiting ferroptosis pathway. Astaxanthin was GPX4 activator that can weaken biological toxicity induced by Cr(VI) exposure. The present study was conducted to evaluate the major role of GPX4 in astaxanthin protects Cr(VI)-induced oxidative damage, blood-brain barrier injury and neurotoxicity in brain-liver axis through inhibiting ferroptosis pathway. In the current study, astaxanthin intervention can effectively alleviate Cr(VI)-induced oxidative stress, blood-brain barrier damage, and neurotoxicity. GPX4 plays a major role in mediating astaxanthin nutritional intervention to reduce ROS and liver non-heme iron accumulation, which would contribute to the reduction of ferroptosis. Meanwhile, astaxanthin maintains the stability of transport receptors and protein macromolecules such as TMEM163, SLC7A11, SLC3A2, FPN1 and GLUT1 in the brain liver axis, promoting substance exchange and energy supply. Moreover, astaxanthin alleviates Cr(VI)-induced neurotoxicity by promoting tight protein expression and reducing blood-brain barrier permeability.

Effect of tandem repeats of antimicrobial peptide CC34 on production of target proteins and activity of Pichia pastoris.

Antimicrobial peptides (AMPs) are attracting attention in the fields of medicine, food, and agriculture because of their broad-spectrum antibacterial properties, low resistance, and low-residue in the body. However, the low yield and instability of the prepared AMP drugs limit their application. In this study, we designed a tetramer of the AMP CC34, constructed and transfected two recombinant expression vectors with pGAPZαA containing a haploid CC34 and tetraploid CC34 (CC34-4js) into Pichia pastoris to explore the effect of biosynthesized peptides. The results showed that CC34 and CC34-4js expression levels were 648.2 and 1105.3 mg/L, respectively, in the fermentation supernatant of P. pastoris. The CC34-4js tetramer showed no antibacterial activity, could be cleaved to the monomer using formic acid, and the hemolytic rate of the polyploid was slightly lower than that of monomeric CC34. The average daily gain, average daily feed intake, feed conversion ratio and immune organ index of rats fed CC34 and CC34-4js showed no differences. In conclusion, CC34-4js exhibited a higher yield and lower hemolysis in P. pastoris than those of CC34. Finally, CC34 and CC34-4js enterokinase lysates showed similar antibacterial activity and both expressed peptides potentially improved the growth performance and organ indices of rats.

Effects of probiotic administration on the digestibility characteristics and growth performance of finishing beef cattle fed a total mixed ration containing different levels of corn stover.

In this study, we aimed to assess the effects of probiotic administration on the digestibility characteristics and growth performance of finishing beef cattle fed a total mixed ration (TMR) containing different levels of corn stover. One hundred and sixty Simmental × Continental crossbred bulls were randomly allocated to two animal houses (80 bulls each) and randomly assigned four TMR differing in the level of corn stover-high (HCT) and low (LCT)-with or without probiotics in each animal house. Feeding HCT supplemented with probiotics increased (P < 0.05) the apparent digestibility of crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Regardless of probiotic supplementation, the nitrogen intake and fecal nitrogen levels of animals fed HCT were lower than those fed LCT (P < 0.05). Additionally, feeding probiotics increased (P < 0.05) the efficiency of ruminal fermentation, final body weight, and average daily gain (ADG) of animals, with this effect being stronger in animals fed HCT. In conclusion, supplementing probiotics with HCT has a positive effect on the growth of finishing beef cattle, thereby providing economic benefits.

In situ and in vitro evaluation of the bioavailability of rumen-protected methionine with coating prototypes.

Rumen protected amino acids are supplements that can enhance ruminal performance, yet the coating designed to protect the amino acids might also lead to different effects. Methionine is an essential methyl donor to synthesize protein, and little data exists on the effects of coating materials on its bioavailability. The purpose of this study was to estimate the effect of rumen-protected methionine (RPM) coatings with different ratios of acrylic resin IV (AR), ethyl cellulose (EC), and a mixture of AR and EC (AREC). Fifteen RPMs were prepared according to a single factor design, with 5 proportions each of AR, EC, and AREC to DL-methionine (DL-Met). Twelve hybrid small-tailed Han sheep with rumen fistula were utilized to evaluate in situ escape of RPMs, followed by in vitro abomasum-intestinal release of the RPMs. The results showed a regular variation in both ruminal disappearance and gastrointestinal release of RPMs with different coating prototypes and retention time. The RPMs that were EC and AREC coated presented high bioavailability compared to those with AR. Bioavailability of RPMs was optimal with the 2:20 AREC: DL-Met ratio, when the proportion of AR:EC is 1:1. Additionally, RPMs with a 1:3 ratio of AR:EC confirmed the optimum effect for the RPM of 2:20 AREC: DL-Met. In conclusion, an RPM with a lower AREC ratio coating can achieve better bioavailability and is synergistic to those with EC and AR.

Antimicrobial peptide CC34 attenuates intestinal inflammation via downregulation of the NF-κB signaling pathway.

The investigational drug CC34 is a cation peptide with multiple bioactivities. Here, we studied the anti-inflammatory effects of CC34 in lipopolysaccharide (LPS)-treated mouse monocyte-macrophage cells (RAW264.7) and in mice with LPS-induced intestinal inflammation. In vitro, CC34 treatment with less than 50 µg/mL for 24 h did not induce cytotoxicity in RAW264.7 cells. Furthermore, CC34 significantly lowered the levels of select inflammatory cytokines, including TNF-α, IL-1ß, and IL-6. Intracellular levels of reactive oxygen species (ROS) were lower in RAW264.7 cells treated with CC34 + LPS than in cells treated with LPS alone. Additionally, CC34 treatment suppressed iNOS and COX-2 mRNA levels in LPS-treated cells. We also observed that CC34 exerted anti-inflammatory activity by suppressing the phosphorylation of IKKß, IκBα, and NF-κB p65 in vitro. Moreover, CC34 downregulated the release of inflammatory cytokines (TNF-α, IL-1ß, and IL-6) in the jejunum tissue and serum of LPS-treated mice. We also found that the myeloperoxidase (MPO) levels were decreased, and the pathological damages were effectively abated in the jejunum tissue of CC34 + LPS-treated mice. In summary, we demonstrated that CC34 exerted anti-inflammatory activities, associated with the neutralization of LPS, inhibition of ROS, inhibition the NF-κB signaling pathway, and down-regulating the secretion of inflammatory cytokines. Thus, CC34 may represent an effective therapeutic strategy for intestinal inflammation.

Toxic effects of hexavalent chromium (Cr6+) on bioaccumulation, apoptosis, oxidative damage and inflammatory response in Channa asiatica.

The objective of this study was to evaluate the toxic effects of Cr6+ on bioaccumulation, digestion, immunity, oxidative stress, apoptosis and inflammation-related genes in Channa asiatica. The fish was exposed to waterborne Cr6+ concentrations (0, 0.5, 1.0 and 2.0 mg/L) for 28 and 56 days. Our results demonstrated that the accumulation of Cr6+ in tissues increased in a concentration-dependent manner, and the content in tissue was liver > gill > gut > muscle. Meanwhile, Cr6+ exposure led to a remarkable suppression of digestion, immunity and antioxidant capacity in C. asiatica. Inversely, MDA and PC content were positively correlated with Cr6+ exposure concentration. Furthermore, the expression of genes went up with the increase of waterborne Cr6+ concentration. Among them, HSP90, NF-κB and TNF-α have a sharp increase. These results elucidate that waterborne Cr6+ exposure may induce bioaccumulation, inhibit digestion and immunity, promote oxidative stress and up-regulate the expression of apoptosis and inflammation-related genes in C. asiatica.

Bioflocs attenuates lipopolysaccharide-induced inflammation, immunosuppression and oxidative stress in Channa argus.

The regulation of C/N in aquaculture water is an important means of environmental regulation, of which the most common is bioflocs technology (BFT). Here, an eight-week feeding experiment and a lipopolysaccharide (LPS) challenge test were proceed to investigate the growth, oxidative stress, immunosuppression and GR-NF-κB related genes expression of Channa argus rearing in the BFT. Four groups were set, the control group was a basic diet (C/N = 7.6:1), and the other three groups were adjusted by glucose, which was C/N 10: 1, C/N 15: 1 and C/N 20:1, respectively. And we detected the two-stage test indexes of C. argus before and after the LPS challenge. The results showed that the bioflocs of C/N 15:1 group significantly (P < 0.05) promoted the growth performance. Similarly, the trend of immune enzyme activity was the same before and after LPS challenge, but decreased after challenge (except AKP and IgM). The best group is still treatment C/N 15:1. Liver and intestine SOD, CAT, GPX, ASA and T-AOC levels of juveniles in treatment C/N 15:1 were markedly increased (P < 0.05) compared to control before and after the LPS challenge. Simultaneously, the content of MDA in control group was considerably higher than that in treatment C/N 15:1 (P < 0.05). Furthermore, C/N 15:1 group significantly down-regulated the expression level of pro-inflammatory factors (NF-κB, TNF-α, IL-1ß and IL-8), and up-regulated IκBα, GR, HSP70 and HSP90 expression levels considerably (P < 0.05). Also, intestinal morphology appeared injury in control group, while intestinal integrity was better in treatment C/N 10:1 and C/N 15:1 after challenge. Taken together, these upshot indicated that bioflocs could enhance growth and alleviate C. argus from LPS-induced oxidative stress, immunosuppression and inflammation through restraining GR-NF-κB signaling pathway. The best C/N ratio for alleviating LPS is 15:1.

Multifocal diffractive lens design in ophthalmology.

Multifocal diffractive lenses are used widely in ophthalmology. This paper provides a general mathematical formula to summarize various multifocal diffractive lens designs and introduces a novel, design: the subzonal multifocal diffractive (SMUD) lens. Analytical and numerical methods of SMUD lens design are elaborated in detail. A number of trifocal and quadrifocal SMUD lens designs of high diffraction efficiency are presented. Fresnel zone spacing factors are introduced to take into account the incidence of a converging or diverging beam and the curvature of the substrate on which the diffractive surface is created. Apodization and ophthalmic astigmatism correction related to diffractive lenses are also discussed.

The optimization of fermentation conditions for Pichia pastoris GS115 producing recombinant xylanase.

Xylanase is a member of an important family of enzymes that has been used in many biotechnological processes. However, the overall cost of enzyme production has been the main problem in the industrial application of enzymes. To obtain maximum xylanase production, statistical approaches based on the Plackett-Burman design and response surface methodology were employed. The results of the statistical analyses demonstrated that the optimal conditions for increased xylanase production were the following: inoculum size, 3.8%; maize meal, 4.5%; histidine, 0.6%; methanol, 1%; culture volume, 20%; bean pulp, 30 g L-1; and Tween-80, 0.8%; and pH 5.0. Verification of the optimization demonstrated that 3273 U mL-1 xylanase was observed under the optimal conditions in shake flask experiments. SDS-PAGE results showed that the size of xylanase protein was about 23 kDa. The results showed that the xylanase produced by fermentation came from Aspergillus Niger by MALDI-TOF-MS. The optimized medium resulted in 2.1- and 1.4-fold higher the activity of xylanase compared with the unoptimized medium (the main nutrients are maize meal and bean pulp) and laboratory medium (the main nutrients are yeast extract and peptone), respectively. The optimization of fermentation conditions is an effective means to reduce production cost and improve xylanase activity.

Amelioration of hexavalent chromium-induced bioaccumulation, oxidative stress, tight junction proteins and immune-related signaling factors by Allium mongolicum Regel flavonoids in Ctenopharyngodon idella.

Chromium (Cr) is the most common heavy metal and that becomes toxic when present at higher concentrations in aquatic environments. Allium mongolicum Regel flavonoids (AMRF) has been documented to possess detoxification, antioxidant and anti-inflammatory properties. The aim of this study was to explore the potential of dietary AMRF and Cr exposure on bioaccumulation, oxidative stress, and immune response in Ctenopharyngodon idella. After acclimation, 360 fish were randomly distributed into six groups. The fish were fed with diets supplemented with Cr and/or AMRF for 4 weeks (28 days), the Cr concentrations were 0, 120, and 240 mg/kg and the concentrations of AMRF were 0 or 40 mg/kg, respectively. The results shown that Cr accumulation in the kidney, liver, spleen, intestine and gill were significantly increased following Cr exposure, dietary AMRF supplementation attenuated the increased in Cr accumulation. Dietary AMRF supplementation significantly reduced the levels of malondialdehyde (MDA) and protein carbonyl (PC) in liver, spleen and gill compared with the same Cr dose groups. When fish were supplemented with AMRF significantly increased lysozyme activity (LZM), complement 3 (C3) in kidney and intestine compared with the same Cr dose groups. Serum glutamic oxalate transaminase (GOT) and glutamic pyruvate transaminase (GPT) were significantly increased following exposure to Cr. Dietary AMRF supplementation significantly decreased GOT and GPT activity in the serum. In addition, AMRF supplementation can decrease the expression of inflammatory (NF-κB p65, TNF-α and IL-1ß) and increased the expression of tight junction proteins (occludin and ZO-1) following Cr exposure in C. idella. These results indicate that AMRF has the potential to alleviate the effects of Cr toxicity in C. idella.

Therapeutic Potential of Trp-Rich Engineered Amphiphiles by Single Hydrophobic Amino Acid End-Tagging.

End-tagging with a single hydrophobic residue contributes to improve the cell selectivity of antimicrobial peptides (AMPs), but systematic studies have been lacking. Thus, this study aimed to systematically investigate how end-tagging with hydrophobic residues at the C-terminus and Gly capped at the N-terminus of W4 (RWRWWWRWR) affects the bioactivity of W4 variants. Among all the hydrophobic residues, only Ala end-tagging improved the antibacterial activity of W4. Meanwhile, Gly capped at the N-terminus could promote the helical propensity of the end-tagged peptides in dodecylphosphocholine micelles, increasing their antimicrobial activities. Of these peptides, GW4A (GRWRWWWRWRA) showed the best antibacterial activity against the 19 species of bacteria tested (GMMIC = 1.86 µM) with low toxicity, thus possessing the highest cell selectivity (TIall = 137.63). It also had rapid sterilization, good salt and serum resistance, and LPS-neutralizing activity. Antibacterial mechanism studies showed that the short peptide GW4A killed bacteria by destroying cell membrane integrity and causing cytoplasmic leakage. Overall, these findings suggested that systematic studies on terminal modifications promoted the development of peptide design theory and provided a potential method for optimization of effective AMPs.

Grape Seed Proanthocyanidin Affects Lipid Metabolism via Changing Gut Microflora and Enhancing Propionate Production in Weaned Pigs.

BACKGROUND: It is not clear whether dietary grape seed proanthocyanidin (GSP) affects mammalian lipid metabolism via the gut microbiota. OBJECTIVE: The aim of this study was to evaluate the contribution of the gut microbiota to the effect of dietary GSP. METHODS: This study was divided into 3 separate experiments using Duroc × Landrace × Yorkshire pigs (50% male) weaned at day 28 and then fed the same basal diet (NC). In Experiment 1, 90 pigs were fed NC or NC with 250 mg GSP/kg (GSP) or 400 mg betaine/kg [positive control (PC)] for 28 d. In Experiment 2, 30 pigs were fed NC, GSP, or GSP with antibiotics (GSP + Abx) diets for 14 d. In Experiment 3, pigs were fed NC, NC plus 1 g sodium propionate/kg (SP), or NC plus 1 g sodium butyrate/kg (SB) diet for 14 d. Serum biochemical indexes, SCFA concentrations, and microbial composition were determined. RESULTS: In Experiment 1, compared with the GSP group, visceral adipocyte area was higher in the NC (28.6%) and PC (18.2%) groups (P ≤ 0.05). Colonic propionate and butyrate concentrations were 30.2% and 3.6% higher in the GSP group than in the NC group, respectively (P ≤ 0.05). In Experiment 2, compared with the GSP group, the NC group had a 108% higher Firmicutes to Bacteroidetes ratio and had 50.4%, 61.2%, and 82.3% lower abundance of Akkermansia, Alistipes, and Bacteroides, respectively (P ≤ 0.05); antibiotics removed these effects of GSP. In Experiment 3, serum peptide YY was 19.5% higher in the SP group than in the NC group (P ≤ 0.05), and it did not differ between the SB and NC groups (P > 0.05). CONCLUSIONS: GSP affected lipid metabolism in weaned pigs, which is associated with changed gut microbiota and enhanced microbial propionate production. These findings provide potential mechanisms for GSP intake to improve lipid metabolism.

Sodium Phenylbutyrate Ameliorates Inflammatory Response Induced by Staphylococcus aureus Lipoteichoic Acid via Suppressing TLR2/NF-κB/NLRP3 Pathways in MAC-T Cells.

This study aimed to investigate the anti-inflammatory properties of sodium phenylbutyrate (SPB) against Staphylococcus aureus (S. aureus) lipoteichoic acid (LTA)-stimulated bovine mammary alveolar (MAC-T) cells. Quantitative PCR was performed to examine the effect of SPB on inflammatory cytokines and host defense peptide (HDP) gene expression. Western blot wanalysis was used to detect the effect of SPB on the TLR2/NF-κB/NLRP3 signaling pathway. The results showed that SPB significantly suppressed the expression of TNF-α, IL-1ß, IL-6; meanwhile, the markedly decreased expression of LTA-stimulated TLR2, NLRP3, ASC, caspase-1, and IL-1ß, and the inhibited IkBα and p65 phosphorylation were also observed. However, increased TAP and Bac5 expression in LTA-stimulated MAC-T cells was further detected. In summary, these results suggest that SPB ameliorates the inflammatory response induced by S. aureus LTA via suppressing the TLR2/NF-κB/NLRP3 signaling pathway, which indicates that SPB may be a potential agent for the treatment of bovine mastitis.

Gut microbiota correlates with fiber and apparent nutrients digestion in goose.

To explore the relationship among the level of fiber, gut microbiota, and nutritional substances, we applied the next generation sequencing technology for the identification of the composition and structure of microbiota in the gastrointestinal tract. In this study, a total of 25 phyla and 298 genera were identified from the gastrointestinal tract; Firmicutes, Bacteroidetes, and Proteobacteria were the predominant phyla. The ability of cecum in carbohydrate metabolism was significantly higher than that of the gizzard and ileum (P < 0.05). The bacterial community structure in various stages of the development of the cecum was different. In the different growth stages of cecum, the increase in the microbiota structure of the fiber level elevates the ability of carbon hydration. Second, the apparent metabolic rates of the other nutrients were affected by the fiber and period except for acid detergent fiber (P < 0.05); the apparent utilization rate of the nutrients increased with time. However, with the increase in the fiber level, the apparent utilization of nutrients was initially increased, followed by a decrease. Therefore, a correlation was established between the fiber level and gastrointestinal microbiota and apparent nutrient utilization rate of the 3 phyla. Our results suggest that the fiber level and growth stages could impact the composition of gut microbiota.

Effects of different amylose to amylopectin ratios on rumen fermentation and development in fattening lambs.

OBJECTIVE: The objective of this experiment was to examine the effects of different amylose/amylopectin ratios on rumen fermentation and development of fattening lambs. METHODS: Forty-eight 7-day-old male Small-tailed Han sheep×Northeast fine wool sheep were randomly assigned to four treatments of dietary amylose/amylopectin ratios (0.12, 0.23, 0.24, and 0.48 in tapioca starch, corn starch, wheat starch and pea starch diets, respectively). Three lambs from each treatment were slaughtered at 21, 35, 56, and 77 days of age to determine the rumen fermentation and development. RESULTS: Compared with tapioca starch diet, the pea starch diet significantly increased the concentration of ammonia nitrogen in the ruminal fluid of lambs but significantly decreased the bacterial protein content. At 56 and 77 d, the rumen propionate concentration tended to be greatest in the tapioca starch group than in other groups. The rumen butyrate concentration was the greatest in lambs fed on pea starch compared with those fed on other starch diets. Furthermore, the pea starch diet significantly stimulated rumen development by increasing the papillae height, width and surface area in the rumen ventral or dorsal locations in lambs. However, different amylose/amylopectin ratios diets did not significantly affect the feed intake, body weight, average daily gain, the relative weight and capacity of the rumen in lambs with increasing length of trial periods. CONCLUSION: Lambs early supplemented with a high amylose/amylopectin ratio diet had favourable morphological development of rumen epithelium, which was not conducive to bacterial protein synthesis.

Separation of motile sperm for in vitro fertilization from frozen-thawed bull semen using progesterone induction on a microchip.

This study presents a novel method for the separation of motile sperm from non-progressive motile and immotile sperm and in vitro Fertilization (IVF). This separation of bull sperm was accomplished by inducing chemotaxis along a progesterone release agent in a 7.5-mm microchannel microchip composed of a biocompatible polydimethysiloxane layer and a glass gradient. The selected sperm was applied directly for IVF. In the first experiment, we tested the effect of different lengths of microchannnel (5mm, 7.5mm and 10mm) on quality parameter of separated sperm. The results showed that separated sperm using 7.5-mm microchannel chip were improved in sperm motility, swimming velocity, and beat frequency compared with other groups. In the second experiment, a medium containing sperm from swim-up method and outlet reservoir of our 7.5-mm microchannel chip was collected and mitochondrial activity of the sperm was determined by fluorescence microscopy. The sperm from the microchip had higher mitochondria activity (47.6%±6.0%) than the sperm from the swim-up method (23.6%±4.7%) (P<0.05). There were significant differences in rate of acrosome intactness between the swim-up method and the microchip (36.0%±4.1% vs. 66.8±2.1%, respectively, P<0.05). In the third experiment, we compared sperm penetration in the microchip-IVF system with a standard IVF method (droplet-IVF). The microchip-IVF group had the highest percentages of oocytes penetrated (82.2%±1.6% vs. 63.5%±2.4%) and monospermic oocytes (67.8%±3.4% vs. 42.4%±1.5%). In addition, early developmental competence of oocytes to the blastocyst stage was higher when the oocytes were inseminated in the microchip-IVF system compared with those inseminated in a standard droplet-IVF system. These results demonstrate that our microchip based on a sperm chemotaxis system is useful for motile sperm separation from frozen-thawed bull semen for IVF. Therefore, the optimized microchip system provides a good opportunity to sort motile bull sperm for IVF.

Temperatures of the Ocular Surface, Lid, and Periorbital Regions of Sjögren's, Evaporative, and Aqueous-Deficient Dry Eyes Relative to Normals.

PURPOSE: To compare the temperatures of the ocular surface, eyelid, and periorbital skin in normal eyes with Sjögren's syndrome (SS) eyes, evaporative dry eyes (EDE), and aqueous deficient dry eyes (ADDE). METHODS: 10 eyes were analyzed in each age-matched group (normal, SS, EDE, and ADDE). A noninvasive infrared thermal camera captured two-dimensional images in three regions of interest (ROI) in each of three areas: the ocular surface, the upper eyelid, and the periorbital skin within a controlled environmental chamber. Mean temperatures in each ROI were calculated from the videos. Ocular surface time-segmented cooling rates were calculated over a 5-s blink interval. RESULTS: Relative to normal eyes, dry eyes had lower initial central OSTs (SS -0.71°C, EDE -0.55°C, ADDE -0.95°C, KW P<.0001) and lower central upper lid temperatures (SS -0.24°C, ADDE -0.51°C, and EDE -0.54°C, KW P<.0001). ADDE eyes had the lowest initial central OST (P<.0001), while EDE eyes had the lowest central lid temperature and lower periorbital temperatures (P<.0001). Over the 5-s interblink interval, the greatest rate of temperature loss occurred following eyelid opening, but varied by group (normals -0.52, SS -0.73, EDE -0.63, and ADDE -0.75°C/s). The ADDE group also had the most substantial heat loss over the 5-s interblink interval (-0.97°C). CONCLUSIONS: Differences in OST may be related to thermal differences in lids and periorbita along with an altered tear film. Thermography of the ocular surface, lids, and surrounding tissues may help to differentiate between different etiologies of dry eye.

Thermal analysis of dry eye subjects and the thermal impulse perturbation model of ocular surface.

In this study, we explore the usage of ocular surface temperature (OST) decay patterns to distinguished between dry eye patients with aqueous deficient dry eye (ADDE) and meibomian gland dysfunction (MGD). The OST profiles of 20 dry eye subjects were measured by a long-wave infrared thermal camera in a standardized environment (24 °C, and relative humidity (RH) 40%). The subjects were instructed to blink every 5 s after 20 âˆ¼ 25 min acclimation. Exponential decay curves were fit to the average temperature within a region of the central cornea. We find the MGD subjects have both a higher initial temperature (p < 0.022) and a higher asymptotic temperature (p < 0.007) than the ADDE subjects. We hypothesize the temperature difference among the subpopulations is due to tear volume and heat transfer mechanisms. To study the validity of our claim, we develop a mathematical model, referred to as the thermal impulse perturbation (TIP) model. We conclude that long-wave-infrared thermal imaging is a plausible tool in assisting with the classification of dry eye patient.