[Posterior scleritis in a dog]. / Posteriore Skleritis bei einem Hund.

Clinical signs, additional diagnostic procedures, treatment, and outcome of a clinically diagnosed posterior scleritis in a male Landseer are reported and discussed in context with the existing literature.

Dacryocystitis in dogs caused by foreign bodies-Diagnosis and therapy in 14 Cases.

OBJECTIVE: To describe foreign bodies (FBs) in the nasolacrimal sac of dogs, the history, and simple diagnostic and therapeutic approaches. Animals studied Fourteen dogs of different breeds, ages, and sexes were presented with unilateral dacryocystitis and had been treated without success for over 1-8 months. PROCEDURES: Patient history, including prior treatment, was obtained from medical records. Slit-lamp examination was performed in all cases (SL 17, Kowa Company Ltd.). Jones tests 1 and/or 2 were performed in 13/14 cases. Dacryocystotomy was initiated with an incision into one canaliculus until the lacrimal sac was exposed and could be explored. After extracting the FB from the nasolacrimal sac, the surgical wound and canaliculus were left open. Aftercare included the administration of antibiotic eye drops with or without dexamethasone and systemic analgesia. RESULTS: All 14 dogs were mesocephalic. Four of them were Dachshunds. Dacryocystotomy revealed plant-related FBs in all cases. The purulent discharge disappeared immediately after removal and did not recur during follow-up. CONCLUSIONS: A simple dacryocystotomy is recommended for dogs with a strong suspicion of a foreign body in the lacrimal drainage system. Dacryocystorhinography appears to be an optional tool in these cases.

Treatment of deep corneal ulcers with porcine small intestinal submusosa using a modified surgical technique in dogs.

Treatment of deep corneal ulcers using small intestinal submucosa (SIS) without corneal sutures in combination with a third eyelid flap seems a promising technical modification. Advantages are a reduction in surgery time and no additional damage of healthy corneal tissue.

Clinical signs of brachycephalic ocular syndrome in 93 dogs.

BACKGROUND: Brachycephalic breeds have anatomical skull changes that are responsible for ocular clinical signs, known as the brachycephalic ocular syndrome (BOS). Their popularity has increased in recent years but the excessive pressure of selection lead to extreme conformation of skull shapes, resulting in facial alterations that can put these dogs' vision at risk. OBJECTIVES: This study aimed to analyse the ocular disorders in a sample of 93 brachycephalic dogs to better characterize the disease complex BOS. MATERIAL AND METHODS: Brachycephalic dogs were submitted to a complete ophthalmological examination. The studied parameters included animal's sex, age and breed, age, ophthalmological tests performed, results of complementary exams, clinical signs, ocular disorders, treatment protocols and their outcomes. Data were organized using Microsoft Office Excel 2007® and statistical analysis was performed with IBM SPSS Statistics 20®. RESULTS: The studied population included 93 brachycephalic dogs 45 males (48%) and 48 females (52%) from different breeds: French Bulldog (n = 38), Shih-Tzu (n = 22), Pug (n = 17), English Bulldog (n = 5), Pekingese (n = 4), Boxer (n = 4) and Boston Terrier (n = 3), aged between 0.2-16 years, median 4.65 years. The most frequent ocular abnormalities were corneal ulcers in 44%, corneal pigmentation in 36%, corneal fibrosis in 25% and entropion in 22% of the animals. There was a higher incidence of corneal pigmentary keratitis in Pugs (53%) and corneal fibrosis in Shih Tzus (36%). The most common surgical techniques were medial canthoplasty in 22%, conjunctival flap in 10% and electroepilation in 7% of the cases, without post-operative complications. CONCLUSIONS: This study contributed to a better characterization of the disease complex brachycephalic ocular syndrome. The percentage of ocular disorders like entropion, corneal pigmentation, fibrosis and ulcers was high, highlighting the importance of a regular ophthalmological check-up, and early diagnosis of the primary disorders. A higher incidence of corneal pigmentation was noticed in Pugs and corneal fibrosis in Shih Tzus, which suggests that some brachycephalic breeds may be predisposed to certain ocular abnormalities. A responsible reproductive strategy should be implemented to avoid undesired transmission of the abnormal traits to the offspring.

Dacryops with extensive lacrimal and maxillary bone defects in four dogs.

OBJECTIVE: To describe and discuss ventromedial orbital lacrimal gland or duct cysts (dacryops) in dogs with extensive bone defects based on their symptoms, results of diagnostic imaging and histopathological examination, and therapy and discuss their potential origin based on the morphology. ANIMALS STUDIED: Four dogs of different breeds, age, and sex were presented with a unilateral round, slow growing, indolent, and non-tender process ventromedial to the nasal canthus of the eye. PROCEDURES: Transverse computed tomography showed a low-density, non-contrast-enhancing cystic process ventromedial to the globe with extensive defects in the lacrimal and maxillary bones in all cases. The cystic character of the structure was confirmed by the aspiration of the brownish fluid without cellular and microbiological contents. For treatment, the cystic fluid was aspirated, and the sclerosing agent polidocanol was injected in three cases. Cystorhinostomy (nasal marsupialisation) was performed in one case as the first choice and in another case following failure of sclerotherapy. Histopathological examination of the cyst walls was performed in two cases and confirmed the diagnosis of dacryops. RESULTS: Follow-up between 2 and 18 months showed no recurrence and very good to excellent cosmetic results. CONCLUSIONS: Aberrant lacrimal gland or duct tissue with secondary development of dacryops should be included in the differential diagnoses of ventromedial orbital cysts. Large cysts near the lacrimal drainage system with extensive bone defects in dogs should be treated by nasal marsupialization. Treatments such as evacuation of the cyst and inducing sclerosis (sclerotherapy) should be reserved for exceptional cases.

The use of a combined sliding skin graft and a free labial mucocutaneous graft for reconstruction of the equine upper eyelid after full-thickness excision of a melanoma.

A melanoma of the upper eyelid was resected in a gray warmblood gelding. A full functional eyelid could be obtained by completion a sliding skin graft with a free labial mucocutaneous graft transplantation to restore the mucocutaneous junction and to decrease the risk of postoperative trichiasis.

Tear glucose, creatinine, and urea nitrogen concentrations in cats with normal or increased plasma concentrations.

OBJECTIVE: The aim of the study was to determine the lacrimal fluid (LF) contents of glucose, urea nitrogen, and creatinine in cats. ANIMAL STUDIED: A total of 96 cats were included in the study. PROCEDURE: Venous blood and LF samples were collected. For LF sampling, three small polyurethane sponges were placed in the ventral fornix of both eyes. Both LF and plasma concentrations of glucose, urea nitrogen, and creatinine were quantitatively analyzed and compared. RESULT: Glucose (n = 40) and urea nitrogen concentrations (n = 42) measured in LF from both eyes highly correlated. While there was a very strong correlation (ρ = 0.97) between urea nitrogen concentrations in blood plasma and the corresponding tear levels (with the median LF urea nitrogen being 109% of that measured in plasma), the LF glucose concentrations were significantly lower than the corresponding plasma concentrations (with only 13% of the blood glucose concentration detected in the LF). The creatinine concentrations in tears were much lower than those in plasma, and LF creatinine was detectable in only 12/48 cats (25%). Hence, a comparison of the LF creatinine concentrations between both eyes or with the corresponding plasma creatinine concentration was not possible. CONCLUSION: Measurement of LF urea nitrogen concentrations in cats appears to be reliable and might have potential clinical utility. Measurement of LF glucose concentrations is less reliable but may still be useful in some cats. Creatinine is not reliably detected in the LF in cats. Further studies determining clinical utility of LF metabolites in cats and other companion animals are warranted.

Superior orbitectomy and chemotherapy in a dog with frontal sinus squamous cell carcinoma: a case report and review of the literature.

A superior orbitectomy can be a challenging but accomplishable surgical option in dogs with a tumor which involves the dorsal bony part of the orbit. The procedure described in this report can be vision-sparing and life prolonging even in a case of an aggressive growing frontal sinus squamous cell carcinoma.

Combining crystallography and EPR: crystal and solution structures of the multidomain cochaperone DnaJ.

Hsp70 chaperones assist in a large variety of protein-folding processes in the cell. Crucial for these activities is the regulation of Hsp70 by Hsp40 cochaperones. DnaJ, the bacterial homologue of Hsp40, stimulates ATP hydrolysis by DnaK (Hsp70) and thus mediates capture of substrate protein, but is also known to possess chaperone activity of its own. The first structure of a complete functional dimeric DnaJ was determined and the mobility of its individual domains in solution was investigated. Crystal structures of the complete molecular cochaperone DnaJ from Thermus thermophilus comprising the J, GF and C-terminal domains and of the J and GF domains alone showed an ordered GF domain interacting with the J domain. Structure-based EPR spin-labelling studies as well as cross-linking results showed the existence of multiple states of DnaJ in solution with different arrangements of the various domains, which has implications for the function of DnaJ.

Suspected macular degeneration in a captive Western lowland gorilla (Gorilla gorilla gorilla).

The case of a 31-year-old captive female Western lowland gorilla (Gorilla gorilla gorilla) with decreased near vision but good distance vision is presented. Examination of the fundus revealed drusen-like bodies in the macula presumably because of an age-related macular degeneration (AMD).

Many of the functional differences between acetohydroxyacid synthase (AHAS) isozyme I and other AHASs are a result of the rapid formation and breakdown of the covalent acetolactate-thiamin diphosphate adduct in AHAS I.

Acetohydroxy acid synthase (AHAS; EC 2.2.1.6) is a thiamin diphosphate (ThDP)-dependent decarboxylase-ligase that catalyzes the first common step in the biosynthesis of branched-chain amino acids. In the first stage of the reaction, pyruvate is decarboxylated and the reactive intermediate hydroxyethyl-ThDP carbanion/enamine is formed. In the second stage, the intermediate is ligated to another 2-ketoacid to form either acetolactate or acetohydroxybutyrate. AHAS isozyme I from Escherichia coli is unique among the AHAS isozymes in that it is not specific for 2-ketobutyrate (2-KB) over pyruvate as an acceptor substrate. It also appears to have a different mechanism for inhibition by valine than does AHAS III from E. coli. An investigation of this enzyme by directed mutagenesis and knowledge of detailed kinetics using the rapid mixing-quench NMR method or stopped-flow spectroscopy, as well as the use of alternative substrates, suggests that two residues determine most of the unique properties of AHAS I. Gln480 and Met476 in AHAS I replace the Trp and Leu residues conserved in other AHASs and lead to accelerated ligation and product release steps. This difference in kinetics accounts for the unique specificity, reversibility and allosteric response of AHAS I. The rate of decarboxylation of the initially formed 2-lactyl-ThDP intermediate is, in some AHAS I mutants, different for the alternative acceptors pyruvate and 2-KB, putting into question whether AHAS operates via a pure ping-pong mechanism. This finding might be compatible with a concerted mechanism (i.e. the formation of a ternary donor-acceptor:enzyme complex followed by covalent, ThDP-promoted catalysis with concerted decarboxylation-carboligation). It might alternatively be explained by an allosteric interaction between the multiple catalytic sites in AHAS.

Oculocardiac reflex in a dog caused by a choroidal melanoma with orbital extension.

A 7 yr old mixed-breed dog was presented with a choroidal melanoma of the left eye that had penetrated the sclera, producing an orbital mass. Bradycardia was detected on auscultation. The bradycardia resolved after exenteration of the orbit and was therefore presumed to be associated with the oculocardiac reflex.

Significant catalytic roles for Glu47 and Gln 110 in all four of the C-C bond-making and -breaking steps of the reactions of acetohydroxyacid synthase II.

Acetohydroxy acid synthase (AHAS) is a thiamin diphosphate (ThDP)-dependent enzyme that catalyzes the first common step in the biosynthesis of branched-chain amino acids, condensation of pyruvate with a second 2-ketoacid to form either acetolactate or acetohydroxybutyrate. AHAS isozyme II from Escherichia coli is specific for pyruvate as the first donor substrate but exhibits a 60-fold higher specificity for 2-ketobutyrate (2-KB) over pyruvate as an acceptor substrate. In previous studies relying on steady state and transient kinetics, substrate competition and detailed analysis of the distribution of intermediates in the steady-state, we have identified several residues which confer specificity for the donor and acceptor substrates, respectively. Here, we examine the roles of active site polar residues Glu47, Gln110, Lys159, and His251 for elementary steps of catalysis using similar approaches. While Glu47, the conserved essential glutamate conserved in all ThDP-dependent enzymes whose carboxylate is in H-bonding distance of the ThDP iminopyrimidine N1', is involved as expected in cofactor activation, substrate binding, and product elimination, our studies further suggest a crucial catalytic role for it in the carboligation of the acceptor and the hydroxyethyl-ThDP enamine intermediate. The Glu47-cofactor proton shuttle acts in concert with Gln110 in the carboligation. We suggest that either the transient oxyanion on the acceptor carbonyl is stabilized by H-bonding to the glutamine side chain, or carboligation involves glutamine tautomerization and the elementary reactions of addition and protonation occur in a concerted manner. This is in contrast to the situation in other ThDP enzymes that catalyze a carboligation, such as, e.g., transketolase or benzaldehyde lyase, where histidines act as general acid/base catalysts. Our studies further suggest global catalytic roles for Gln110 and Glu47, which are engaged in all major bond-breaking and bond-making steps. In contrast to earlier suggestions, Lys159 has a minor effect on the kinetics and specificity of AHAS II, far less than does Arg276, previously shown to influence the specificity for a 2-ketoacid as a second substrate. His251 has a large effect on donor substrate binding, but this effect masks any other effects of replacement of His251.

Valine 375 and phenylalanine 109 confer affinity and specificity for pyruvate as donor substrate in acetohydroxy acid synthase isozyme II from Escherichia coli.

Acetohydroxy acid synthase (AHAS) is a thiamin diphosphate-dependent enzyme that catalyzes the condensation of pyruvate with either another pyruvate molecule (product acetolactate) or 2-ketobutyrate (product acetohydroxybutyrate) as the first common step in the biosynthesis of branched-chain amino acids in plants, bacteria, algae, and fungi. AHAS isozyme II from Escherichia coli exhibits a 60-fold higher specificity for 2-ketobutyrate (2-KB) over pyruvate as acceptor, which was shown to result from a stronger hydrophobic interaction of the ethyl substituent of 2-KB with the side chain of Trp464 in multiple, apparently committed steps of catalysis. Here, we have elucidated the molecular determinants conferring specificity for pyruvate as the sole physiological donor substrate. Structural studies and sequence alignments of the POX subfamily of ThDP enzymes that act on pyruvate indicate that a valine and a phenylalanine hydrophobically interact with the methyl substituent of pyruvate. Kinetic and thermodynamic studies on AHAS isozyme II variants with substitutions at these positions (Val375Ala, Val375Ile, and Phe109Met) were carried out. While Val375 variants exhibit a slightly reduced k(cat) with a moderate increase of the apparent K(M) of pyruvate, both substrate affinity and k(cat) are significantly compromised in AHAS Phe109Met. The specificity for 2-ketobutyrate as acceptor is not altered in the variants. Binding of acylphosphonates as analogues of donor substrates was analyzed by circular dichroism spectroscopy and stopped-flow kinetics. While binding of the pyruvate analogue is 10-100-fold compromised in all variants, Val375Ala binds the 2-KB analogue better than the wild type and with higher affinity than the pyruvate analogue, suggesting steric constraints imposed by Val375 as a major determinant for the thermodynamically favored binding of pyruvate in AHAS. NMR-based intermediate analysis at steady state reveals that a mutation of either Val375 or Phe109 is detrimental for unimolecular catalytic steps in which tetrahedral intermediates are involved, such as substrate addition to the cofactor and product liberation. This observation implies Val375 and Phe109 to not only conjointly mediate substrate binding and specificity but moreover to ensure a proper orientation of the donor substrate and intermediates for correct orbital alignment in multiple transition states.

Development of feline microsatellites and SNPs for evaluating primary cataract candidate genes as cause for cataract in Angolan lions (Panthera leo bleyenberghi).

Primary cataracts (CAT) are characterized as any form of opacities of the eye lenses and are not accompanied by other diseases. CAT may impair vision depending on their size, location, and their state of progression. In order to investigate the cause of congenital or juvenile CAT in inbred Angolan lions kept in German zoos, we analyzed the genomic sequences of 4 crystalline genes CRYAA, CRYAB, CRYBB2, and CRYBB1. In addition, 10 CAT candidate genes (GJA3, LIM2, CRYGA, CRYGB, CRYGC, CRYGD CRYGS, BFSP2, CRYBA4, and CRYBB1) were analyzed using adjacent microsatellites. We identified 10 single nucleotide polymorphisms in the Angolan lion crystalline genes and 9 segregating microsatellites. Nonparametric and parametric linkage analyses did not reveal any linkage between one of the analyzed markers and CAT. So, we concluded that these genes can be excluded as causative for the familial primary cataract phenotype in these Angolan lions.

Surgical removal of a dermoid cyst from the bony part of the nasolacrimal duct in a Scottish highland cattle heifer.

The ophthalmologic, radiologic and surgical findings of a 2-year-old Scottish Highland Cattle heifer with a dermoid cyst within the bony part of the nasolacrimal duct and the successful treatment are presented.

Glyoxylate carboligase lacks the canonical active site glutamate of thiamine-dependent enzymes.

Thiamine diphosphate (ThDP), a derivative of vitamin B1, is an enzymatic cofactor whose special chemical properties allow it to play critical mechanistic roles in a number of essential metabolic enzymes. It has been assumed that all ThDP-dependent enzymes exploit a polar interaction between a strictly conserved glutamate and the N1' of the ThDP moiety. The crystal structure of glyoxylate carboligase challenges this paradigm by revealing that valine replaces the conserved glutamate. Through kinetic, spectroscopic and site-directed mutagenesis studies, we show that although this extreme change lowers the rate of the initial step of the enzymatic reaction, it ensures efficient progress through subsequent steps. Glyoxylate carboligase thus provides a unique illustration of the fine tuning between catalytic stages imposed during evolution on enzymes catalyzing multistep processes.

Factors affecting intraocular pressure in lions.

The aim of this study was to conduct a detailed analysis of the relationship between age and intraocular pressure (IOP) in lions. Tonometry was conducted in 33 lions aged 5 days to 80 months. Age was significantly associated with IOP (P<0.005). Mean IOP was 12.8+/- and 23.9+/-4.1 mmHg in lions < or =1 year old and >1 year old, respectively. IOP linearly rose with age during the first 20 months of life, plateaued until approximately 40 months, and then gradually declined (r=0.85). Age-related changes in IOP were highly correlated with ultrasonographic measurements of intraocular dimensions (r > or = 0.72), and may be a determinant factor in developmental ocular growth. The dramatic rise in IOP of young lions is similar to that observed in children, but has not been previously demonstrated in animals. Significant IOP differences between lion sub-species were also demonstrated.

The catalytic cycle of a thiamin diphosphate enzyme examined by cryocrystallography.

Enzymes that use the cofactor thiamin diphosphate (ThDP, 1), the biologically active form of vitamin B(1), are involved in numerous metabolic pathways in all organisms. Although a theory of the cofactor's underlying reaction mechanism has been established over the last five decades, the three-dimensional structures of most major reaction intermediates of ThDP enzymes have remained elusive. Here, we report the X-ray structures of key intermediates in the oxidative decarboxylation of pyruvate, a central reaction in carbon metabolism catalyzed by the ThDP- and flavin-dependent enzyme pyruvate oxidase (POX)3 from Lactobacillus plantarum. The structures of 2-lactyl-ThDP (LThDP, 2) and its stable phosphonate analog, of 2-hydroxyethyl-ThDP (HEThDP, 3) enamine and of 2-acetyl-ThDP (AcThDP, 4; all shown bound to the enzyme's active site) provide profound insights into the chemical mechanisms and the stereochemical course of thiamin catalysis. These snapshots also suggest a mechanism for a phosphate-linked acyl transfer coupled to electron transfer in a radical reaction of pyruvate oxidase.