Evaluation of nasolacrimal fluorescein transit time in ophthalmically normal dogs and nonbrachycephalic cats

OBJECTIVE

To evaluate fluorescein nasolacrimal transit (NLT) times in ophthalmically normal dogs and nonbrachycephalic cats by use of 2 methods of the Jones test.

ANIMALS

73 dogs and 36 cats.

PROCEDURES

Fluorescein dye was applied to the ocular surface of both eyes by means of a wetted fluorescein strip and, in a subsequent test, by administration of a drop of 0.2% fluorescein solution. During each test, the nares were monitored for the appearance of fluorescein for up to 30 minutes after application. Time of fluorescein appearance at the nares was recorded as NLT time. Recorded variables for all study animals included age, reproductive status, body weight, and Schirmer tear test values. For dogs, skull index, snout length, and cephalic conformation were also recorded. Data were grouped for statistical comparisons according to test results.

RESULTS

In both dogs and cats, NLT was faster when the fluorescein solution versus fluorescein strip was used. In cats, none of the recorded variables had a significant effect on NLT, irrespective of the testing method used. In dogs, several variables had a significant effect on NLT, including cephalic conformation, snout length, age, and reproductive status, but these findings varied with testing method and testing group.

CONCLUSIONS AND CLINICAL RELEVANCE

NLT was highly variable in dogs and cats, regardless of testing method used. Assessment of nasolacrimal patency in brachycephalic dogs by use of either method evaluated here is not likely to be clinically useful. In cats, assessment of nasolacrimal patency with the fluorescein drop method was faster and more conclusive than with the fluorescein strip method.

Outcomes of nonsurgical management and efficacy of demecarium bromide treatment for primary lens instability in dogs: 34 cases (1990-2004)

OBJECTIVE

To determine outcome of initial conservative management for primary lens luxation and evaluate topically administered demecarium bromide miotic treatment for prevention of anterior lens luxation, glaucoma, and vision loss in dogs.

DESIGN

Retrospective case series.

ANIMALS

34 dogs with primary lens luxation.

PROCEDURES

Medical records of affected dogs were reviewed for times to anterior luxation, luxation of the lens in the opposite eye, development of glaucoma, and vision loss.

RESULTS

At 4 to 6 weeks and at 3 months after diagnosis of lens instability (subluxation or posterior luxation), 100% (34/34 and 29/29, respectively) of conservatively managed eyes retained vision. At 1 year after diagnosis of lens instability, 80% (16/20) of conservatively managed eyes retained vision, and at 2 years after diagnosis of lens instability, 11 of 19 conservatively treated eyes retained vision. The only significant effect of miotic treatment was to delay anterior lens luxation in eyes with lens instability. Miotic treatment did not significantly affect the time from anterior lens luxation in 1 eye to anterior luxation in the other eye, time to onset of glaucoma, or time to loss of vision in eyes with an unstable lens.

CONCLUSIONS AND CLINICAL RELEVANCE

Prophylactic topically administered miotic treatment may be effective at delaying anterior luxation of an unstable lens in eyes affected by primary lens instability. Conservative medical management of dogs with primary lens instability is a reasonable alternative to surgical removal of a subluxated or posteriorly luxated lens via intracapsular lens extraction.

Duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in clinically normal cats

OBJECTIVE

To determine duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in domestic shorthair (DSH) cats.

ANIMALS

20 clinically normal DSH cats.

PROCEDURES

Baseline corneal touch threshold (CCT) was established by use of a Cochet-Bonnet aesthesiometer. Treatment consisted of a single 50-microL topical application of an ophthalmic preparation of 0.5% proparacaine solution to a randomly selected eye of each cat. The corneal touch threshold was assessed 1 and 5 minutes after application to the cornea and at 5- minute intervals thereafter for 60 minutes.

RESULTS

Corneal sensitivity, as determined by Cochet-Bonnet aesthesiometry, was significantly reduced from baseline for 25 minutes following topical administration of ophthalmic proparacaine. Maximal anesthetic effect lasted 5 minutes.

CONCLUSIONS AND CLINICAL RELEVANCE

As determined by Cochet-Bonnet aesthesiometry, duration of anesthetic effects on the cornea induced by a single topical application of an ophthalmic preparation of 0.5% proparacaine solution in DSH cats is considerably shorter than the reported duration of corneal anesthesia in dogs.

Molecular characterization of mtDNA depleted and repleted NT2 cell lines

Transmitochondrial cytoplasmic hybrids (cybrids) enable functional assessment of mitochondrial DNA (mtDNA)-encoded proteins. Cybrid production often utilizes cell lines depleted of endogenous mtDNA (rho0 cells), and a number of suitable rho0 cell lines exist for this purpose. We now provide molecular data characterizing an NT2 human teratocarcinoma rho0 cell line, as well as NT2 cybrid derivatives. NT2 rho0 cells contained no detectable mtDNA on a sensitive PCR assay. Eight weeks after exogenous mtDNA transfer cybrids showed no evidence of endogenous mtDNA reversion, and heteroplasmic ratios of a single nucleotide substitution roughly reflected that of the blood samples used to repopulate their mtDNA.

Mitochondrial DNA depletion analysis by pseudogene ratioing

The mitochondrial DNA (mtDNA) depletion status of rho(0) cell lines is typically assessed by hybridization or polymerase chain reaction (PCR) experiments, in which the failure to hybridize mtDNA or amplify mtDNA using mtDNA-directed primers suggests thorough mitochondrial genome removal. Here, we report the use of an mtDNA pseudogene ratioing technique for the additional confirmation of rho0 status. Total genomic DNA from a U251 human glioma cell line treated with ethidium bromide was amplified using primers designed to anneal either mtDNA or a previously described nuclear DNA-embedded mtDNA pseudogene (mtDNApsi). The resultant PCR product was used to generate plasmid clones. Sixty-two plasmid clones were genotyped, and all arose from mtDNApsi template. These data allowed us to determine with 95% confidence that the resultant mtDNA-depleted cell line contains less than one copy of mtDNA per 10 cells. Unlike previous hybridization or PCR-based analyses of mtDNA depletion, this mtDNApsi ratioing technique does not rely on interpretation of a negative result, and may prove useful as an adjunct for the determination of rho0 status or mtDNA copy number.

Biochemical analysis of cybrids expressing mitochondrial DNA from Contursi kindred Parkinson's subjects

Complex I activity is reduced in cytoplasmic hybrid (cybrid) cell lines that contain mitochondrial DNA (mtDNA) from sporadic Parkinson's disease (PD) patients. This implies that mtDNA aberration occurs in sporadic PD. To assess the integrity of mtDNA in autosomal dominant PD arising from mutation of the alpha-synuclein gene, we transferred mitochondrial genes from PD-affected members of the Italian-American Contursi kindred to cells previously depleted of their endogenous mtDNA. Unlike cybrid cell lines expressing mtDNA from persons with sporadic or maternally inherited PD, the resultant Contursi cybrid lines did not manifest complex I deficiency, indicating that in Contursi PD mtDNA integrity is relatively preserved. Compared to control cybrids, however, Contursi cybrid lines did show some evidence of oxidative stress. For reasons that are unclear, at least a limited amount of mtDNA damage may nevertheless develop in PD patients with alpha-synuclein mutation.

Mitochondrial dysfunction in cybrid lines expressing mitochondrial genes from patients with progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a neurodegenerative movement disorder of unknown etiology. We hypothesized that mitochondrial DNA (mtDNA) aberration could occur in this disease and contribute to its pathogenesis. To address this we created transmitochondrial cytoplasmic hybrid (cybrid) cell lines expressing mitochondrial genes from persons with PSP. The presence of cybrid mtDNA aberration was screened for by biochemical assay of mitochondrial gene products. Relative to a control cybrid set, complex I activity was reduced in PSP cybrid lines (p<0.005). Antioxidant enzyme activities were elevated in PSP cybrid lines. These data suggest that mtDNA aberration occurs in PSP, causes electron transport chain pathology, and can produce oxidative stress. Further study of mitochondrial dysfunction in PSP may yield insights into why neurodegeneration occurs in this disease.