Ultrasound biomicroscopic findings of the iridocorneal angle in live healthy and glaucomatous dogs

By using ultrasound biomicroscopy (UBM), the cross-sectional structures of the entire iridocorneal angle (ICA) which are unable to assess with gonioscopic examination were evaluated objectively and quantitatively in live healthy and glaucomatous dogs. The ICAs of normotensive eyes in healthy dogs with normal open angle (NOR), a predisposition to primary closed angle glaucoma (PCAG) (PREDIS) and suffering from unilateral PCAG (UNI), as well as the ICAs of hypertensive eyes with acute and chronic PCAG (ACG and CRG), were assessed. The opening of the ciliary cleft in PREDIS was smaller than that in NOR. In UNI, the opening and area of the ciliary cleft were significantly decreased compared with those of NOR and PREDIS. ACG had widespread structural abnormalities including marked decrease in the ciliary cleft and scleral venous plexus, and a thinner sclera than those in normotensive eyes, whereas the ICA collapsed in CRG with the thinnest sclera. Medical therapy-responsive glaucomatous cases had wider ciliary cleft and scleral venous plexus than unresponsive ones. These findings suggest that the ciliary cleft and scleral venous plexus of the ICA are key structures contributing to not only the pathophysiology of canine glaucoma but also the responsiveness to medical therapy in glaucomatous eyes, and cross-sectional entire structures of the ICA should be evaluated quantitatively with UBM when diagnosing and managing canine glaucoma.     

Schwalbe line's cell in the normal and glaucomatous dog

Objective The canine iridocorneal angle contains an operculum, which is similar to that in nonhuman primates and consists of a peripheral extension of the inner cornea that overlies the anterior‐most portion of the corneoscleral trabecular meshwork. This region contains cells, the Schwalbe line’s (SL) cells, that have been found to have secretory and epithelial characteristics. This region of the iridocorneal angle represents the nonfiltering portion and becomes altered early during spontaneous glaucoma in the Beagle. The present study describes the SL cell for the first time in the dog and changes associated with canine primary open angle glaucoma. Procedures The iridocorneal angles from 18 Beagles with inherited glaucoma (3 months–8 years old) and 17 normal, age‐matched Beagles were placed in 10% buffered formalin for light microscopic evaluation, or 2.5% glutaraldehyde for ultrastructural evaluation. Using at least three fields from each region of the iridocorneal angle (opercular, corneoscleral, and uveal) at ×1000 magnification, trabecular cell nuclei were counted. Results The operculum in the canine iridocorneal angle consisted of the peripheral extension of the corneal endothelium and underlying anterior‐most corneoscleral meshwork, having no direct contact with the angular aqueous plexus. The SL cells associated with operculum‐retained epithelial morphology (polyhedral in shape with rER, Golgi apparatus, and secretory vesicles) in both normal, pre‐and early glaucomatous dogs. In animals with moderate and advanced stages the SL cells often became less epithelial and secretory in appearance. The number of SL cells in normal dogs declined by approximately one‐third by the end of their first year with gradual loss thereafter. In the glaucoma group the decline was more substantial and continuous through the first three years. Conclusions The SL cell is morphologically a distinct cell type within the canine iridocorneal angle that is specifically associated with the nonfiltering portion of the corneoscleral trabecular meshwork. Changes in the SL cells of the glaucomatous dog occurred with regard to age and progression of the disease.     

Relationship of the iridocorneal angle, as measured using ultrasound biomicroscopy, with post-operative increases in intraocular pressure post-phacoemulsification in dogs

Objective  To investigate the relationship of the iridocorneal angle as it appears on ultrasound biomicroscopy (UBM) to increases in IOP post-phacoemulsification in the canine eye.
Animals studied  47 eyes of 28 dogs of various age, sex, and breed.
Methods  The ciliary process and limbus were used as a reference points to measure the angle opening distance (AOD), which was set by multiplying 0.45 by the distance between the ciliary process and limbus (when measured from the ciliary process). Pressure measurements were taken at five set points: Before, immediately post-, one day post-, 1 week post-, and 1 month post-phacoemulsification.
Results  A weak relationship between the AOD and the IOP one day post-phacoemulsification (Intercept: 2.83, Slope: –1.24, P -value: 0.0155) was observed. No relationship immediately post-operative (Intercept: 3.45, Slope: –1.34, P -value: 0.0651), 1 week post-phacoemulsification (Intercept: 2.31, Slope: –0.01, P -value: 0.9829), 1 month post-phacoemulsification (Intercept: 1.85, Slope: –0.49, P -value: 0.1533) was observed. The pre-operative measurements made with UBM were: Distance from limbus to ciliary process (DLCP): (Minimum: 1.152, Maximum: 2.992, Mean: 1.91, SD: 0.468); AOD (Minimum: 0.104, Maximum: 0.764, Mean: 0.40, SD: 0.172).
Conclusions  The relationship between AOD as measured by UBM pre-operatively is weakly associated with IOP pressure elevations at day one post-phacoemulsification. Further study is required prospectively to establish the importance of this relationship. Initial measurements of the canine iridocorneal angle were created, suggesting a method to be used in the future to establish true canine normal measurements.     

Comparison of three rebound tonometers in normal and glaucomatous dogs

Objective

The objectives of the study were to compare intraocular pressure (IOP) readings across a wide range and obtained via three rebound tonometers in ADAMTS10-mutant Beagle-derived dogs with different stages of open-angle glaucoma (OAG) and normal control dogs and to investigate the effect of central corneal thickness (CCT).

Animals Studied

Measurements were performed on 99 eyes from 50 Beagle-derived dogs with variable genetics—16 non-glaucomatous and 34 with ADAMTS10-OAG. Seventeen OAG eyes were measured twice—with and without the use of IOP-lowering medications.

Procedures

IOP was measured in each eye using three tonometers with their “dog” setting—ICare® Tonovet (TV), ICare® Tonovet Plus® (TVP), and the novel Reichert® Tono-Vera® Vet (TVA)—in randomized order. CCT was measured with the Accutome® PachPen. Statistical analyses included one-way ANOVA, Tukey pairwise comparisons, and regression analyses of tonometer readings and pairwise IOP-CCT Pearson correlations (MiniTab®).

Results

A total of 116 IOP measurements were taken with each of the three tonometers. When comparing readings over a range of ~7–77 mmHg, mean IOPs from the TV were significantly lower compared with TVP (−4.6 mmHg, p < .001) and TVA (−3.7 mmHg, p = .001). We found no significant differences between TVA and TVP measurements (p = .695). There was a moderate positive correlation between CCT and IOP for TVA (r = 0.53, p < .001), TVP (r = 0.48, p < .001), and TV (r = 0.47, p < .001).

Conclusions

Our data demonstrate strong agreement between TVP and TVA, suggesting that the TVA may similarly reflect true IOP values in canines. CCT influenced IOP measurements of all three tonometers.     

Structure and presumptive function of the iridocorneal angle of the West Indian manatee (Trichechus manatus), short-finned pilot whale (Globicephala macrorhynchus), hippopotamus (Hippopotamus amphibius), and African elephant (Loxodonta africana)

The iridocorneal angles of prepared eyes from the West Indian manatee, short-finned pilot whale, hippopotamus and African elephant were examined and compared using light microscopy. The manatee and pilot whale demonstrated capacity for a large amount of aqueous outflow, probably as part of a system compensating for lack of ciliary musculature, and possibly also related to environmental changes associated with life at varying depths. The elephant angle displayed many characteristics of large herbivores, but was found to have relatively low capacity for aqueous outflow via both primary and secondary routes. The hippopotamus shared characteristics with both land- and water-dwelling mammals; uveoscleral aqueous outflow may be substantial as in the marine mammals, but the angular aqueous plexus was less extensive and a robust pectinate ligament was present. The angles varied greatly in size and composition among the four species, and most structures were found to be uniquely suited to the habitat of each animal.     

Effects of oral isosorbide and glycerol on intraocular pressure,serum osmolality,and blood glucose in normal dogs

Objective To evaluate and compare the effects of oral isosorbide and glycerol on intraocular pressure (IOP), serum osmolality (SOSM), and blood glucose (BG) in normal dogs. Methods Ten normal dogs were administered an oral dose of either isosorbide (1.5 g/kg), glycerol (1.5 g/kg) or control (water, 2 mL/kg) in a double blind protocol. Prior to dosing, baseline IOP, SOSM, and BG were measured in all dogs. IOP was subsequently evaluated every 30 min for 6 h post‐dosing. BG and SOSM were reassessed at times 1, 2, 4, and 6 h post‐dosing. After 1‐week washout periods, every dog was subject to each of the three treatments. The dogs were held NPO for 4 h after dosing. Results The maximal decrease in IOP was 17% by 1 h and 13.5% by 30 min after glycerol and isosorbide administration, respectively. However, the overall changes in IOP were not significant when compared to the controls. SOSM increased above baseline after dosing with glycerol but decreased after isosorbide, which difference was significant at 1, 2, and 4 h post‐administration. BG significantly increased after administration of glycerol relative to the control but was not significantly affected by isosorbide. Conclusions Neither glycerol nor isosorbide significantly affected IOP when compared to the control. However, glycerol induced significant elevations in both BG relative to the control and SOSM relative to isosorbide.     

Evaluation of the distance between Schwalbe’s line and the anterior lens capsule as a parameter for the correction of ultrasound biomicroscopic values of the canine iridocorneal angle

Objective To determine whether the distance between Schwalbe’s line (the peripheral termination of Descemet’s membrane, i.e., the borderline between the cornea and sclera) and the anterior lens capsule (SLD) is an applicable parameter for correcting raw ultrasound biomicroscopic values of the canine iridocorneal angle (ICA) and to establish a comparative system for the ICA values in different canine breeds with varied body sizes/weights. Animal studied The dogs were divided into four groups based on body weight (BW): <4 kg, 4–8 kg, 8–20 kg, and >20 kg, and 180 normotensive eyes were studied. Procedures The ICA microstructure was examined by ultrasound biomicroscopy (UBM) using 40‐MHz probes in dogs with or without anesthesia/sedation. Linear regression analysis and correlation coefficients were evaluated between SLD or SLD² and UBM measurements; subsequently, noncorrected and SLD‐corrected UBM values were statistically assessed. Results Significant linear correlations were detected between SLD and the ciliary cleft width, the minimum distance between the angle recess and the scleral venous plexus, and the scleral thickness. Positive linear correlations were also demonstrated between SLD² and the ciliary cleft area as well as the scleral venous plexus area. Raw UBM measurements were corrected by using a ratio with SLD on the distance or SLD² on the area. Although noncorrected UBM measurements increased with canine BW, SLD‐corrected UBM values remained similar with no significant statistical differences in any of the dogs. Conclusions Correction with SLD would be clinically useful for comparing UBM measurements of the ICA in dogs with different body sizes/weights.     

Pectinate ligament dysplasia and narrowing of the iridocorneal angle associated with glaucoma in the English Springer Spaniel

Objective The aim of the study was to evaluate if tonometry and gonioscopy could serve as predictors of later glaucoma development in the English Springer Spaniel, a breed prone to developing primary glaucoma. Animals studied Gonioscopy was performed on 279 English Springer Spaniel dogs, 119 males and 160 females, with clinically normal eyes. In addition, 14 dogs, five males and nine females were examined for glaucoma. Results A positive relation between pectinate ligament dysplasia (PLD) and narrowing of the relative width of the ciliary cleft (RWOCC) and also between PLD, RWOCC and age was demonstrated. The prevalence of PLD was 25.5%, which is higher than in other breeds reported. A positive association was demonstrated between PLD and glaucoma, as well as between narrowing of the RWOCC and glaucoma. Glaucoma was not observed in dogs with normal appearance of the iridocorneal angle. English Springer Spaniels related to dogs with glaucoma show more narrowing of the RWOCC and more PLD than unrelated dogs. Conclusion This study demonstrates the positive association between PLD and glaucoma, between narrowing of the iridocorneal angle and glaucoma and the effect of age on the iridocorneal angle. Mating of dogs with normal iridocorneal angles appears to reduce the presence and degree of abnormal appearance of the iridocorneal angle in the offspring. However, breeding only dogs with normal iridocorneal angles without consideration of their relationship to dogs with glaucoma is not a guarantee for preventing glaucoma in the offspring.     

肺炎支原体对大鼠气管平滑肌细胞损害作用的研究

采用贴片法进行大鼠气管平滑肌细胞的培养，将不同稀释度的肺炎支原体培养液接种于单层细胞中孵育。对次日收集的细胞上清液进行肺炎支原体的PCR反应检测，结果为阳性，而冲洗液反应阴性，表明支原体对细胞具有较强的粘附性；接种后7d内观察到细胞产生明显病变，部分细胞发生崩解、脱落。MTT法检测结果表明支原体使细胞活性明显降低，其致细胞死亡率随滴度增高而增加，提示肺炎支原体对大鼠气管平滑肌可产生很强的致病性，使呼吸道受到严重损伤。本研究为探讨肺炎支原体致病作用机制及新药筛选与评价提供一种新的方法。     

Ultrasonographic measurement of caudal vena cava to aorta ratios for determination of volume depletion in normal beagle dogs

A noninvasive method for quantifying hydration status would be helpful for clinical management and for research applications in dogs. This prospective, experimental, pilot study aimed to assess the feasibility of ultrasonographic measurement of the caudal vena cava to aorta ratio as a method for quantifying volume depletion in dogs. In 12 normal beagle dogs, furosemide was administered intravenously at a dose of 1 mg/kg, every 2 h, for 8 h, to induce consecutive volume depletion. Every 30 min after administration, ultrasonographic images of the caudal vena cava and aorta, and physical and biological parameters related to dehydration were acquired. On transverse and longitudinal planes of caudal vena cava and aorta images, the height and area of the caudal vena cava and aorta were measured to calculate the caudal vena cava/aorta ratios. All images were acquired by approaching from the right intercostal space with the dogs in left lateral recumbency. A negative correlation was present between the percentage of weight loss in dogs and all four investigated caudal vena cava/aorta ratios (transverse plane width of the caudal vena cava [TW]/aorta; transverse plane height of caudal vena cava [TH]/aorta; longitudinal plane area of the caudal vena cava [TA]/aorta; and longitudinal plane maximal height of the caudal vena cava [L]/aorta). Significant differences (P < 0.001) were seen between dogs with and without clinical signs of dehydration for all caudal vena cava/aorta ratios. Findings indicated that ultrasonographic caudal vena cava/aorta ratios are feasible methods for quantifying volume depletion and for use as an adjunct to standard subjective methods for estimating hydration status in dogs.     

Extraction and characterization of collagens from yak rumen smooth muscle

This study reports an effective method using enzymatic methods to extract collagen from yak rumen smooth muscle. The enzymatic extraction methods were optimized by response surface methodology. Additionally, the properties of the extracted collagen were analyzed by Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry (MS). The results showed that the optimal conditions were as follows: the pepsin addition was 0.95%, the enzymatic hydrolysis time was 21 hr, and the solid‐to‐solvent ratio was 1:11. Under these conditions, the collagen extraction rate could reach 3.62/100 g. The results of FT‐IR revealed that the amide A, amide B, amide I, amide II, and amide III bands of the collagen appeared at 3,293.18, 3,068.18, 1654.94, 1,540.58, and 1,236.58 cm^?1, respectively. The MS identified seven types of collagen, which were type I, type III, type IV, type V, type VI, type VIII, and type XII. The results demonstrated that the enzymatic method can extract collagen from yak rumen smooth muscle with a considerably high yield and can preserve the intact structure of the collagen.     

Effect of glucocorticoid administration on adrenal gland size and sonographic appearance in beagle dogs

Our aim was to evaluate the influence of glucocorticoids on the adrenal gland using ultrasonography. Eleven healthy beagles were used in a prospective placebo-controlled study. All dogs received hydrocortisone at 10 mg/kg twice a day per os for 4 months or a gelatin capsule twice a day per os as a placebo. Clinical and endocrinologic examination of the dogs and ultrasonographic evaluation of adrenal echogenicity, shape, and measurement of the length and height of the cranial and caudal pole were performed at baseline (TO), at 1 (T1) and 4 months (T4) after the beginning of treatment, and 2 months after the end of the treatment including 1 month of tapering and 1 month without treatment (T6). The dogs were assigned randomly to the glucocorticoid (n = 6) and placebo groups (n = 5). At T1, the difference between the two groups for the height of the cranial and caudal pole was not ultrasonographically remarkable despite a statistically significant difference (P = 0.0165 and P = 0.0206). Decreased height and length of entire gland were observed at T4 (P < 0.0001, P = 0.0015, and P = 0.0035, respectively). Percentages of atrophy were variable between dogs. Both adrenal glands regained normal size and shape 1 month after cessation of glucocorticoid administration. As not all dogs developed marked adrenal gland atrophy and the degree of atrophy varied widely between individuals, ultrasonography cannot be the technique of choice to detect iatrogenic hypercortisolism. Ultrasonographic changes are reversible within 1 month after the end of glucocorticoid administration.