Clinical study on the application of dexamethasone and cyclosporine/dimethyl sulfoxide combination eye drops in the initial therapy of chronic superficial keratitis in dogs.

PURPOSE: To assess the initial therapy of chronic superficial keratitis (CSK) in dogs with the use of dexamethasone and cyclosporine/ dimethyl sulfoxide combination eye drops. METHODS: The study was conducted on 41 dogs - 16 males and 25 females, aged 2 to 9 years, diagnosed with CSK. The disease was treated with two kinds of eye drops containing 0.1% dexamethasone and 0.75% cyclosporine in combination with 30% DMSO, administered three times a day. Prior to the treatment and after 5 weeks of therapy, depigmentation of the third eyelid margin, corneal neovascularization and pigmentation were assessed. The percentage of the corneal surface afflicted with inflammatory processes was calculated with the use of IsoCalc.com's Get Area software for CorelDRAW12. RESULTS: The administered therapy resulted in a significant decrease in the mean number of quadrants affected by corneal neovascularization in the right eye from 2.63 prior to treatment to 0.24 after treatment (p⟨0.001), and the left eye from 2.66 to 0.59 (p⟨0.001), respectively. Mean corneal surface afflicted with inflammatory processes was statistically significantly reduced from 53.5% to 26.3% (p⟨0.001) in the case of right corneas, and from 54.5% to 30.2% (p⟨0.001) in the case of left corneas. Of 77 corneas diagnosed with pigmentation, pigmentation reduction was observed in 54 and pigmentation increase in 27. CONCLUSIONS: Using dexamethasone and cyclosporine/DMSO combination eye drops proved to be a viable initial therapy against CSK, which facilitates reduction of inflammatory processes and neovascularization atrophy, but in many cases does not inhibit the progress of pigmentation.

Epigenetic regulation of the MGMT and hMSH6 DNA repair genes in cells resistant to methylating agents.

We investigated the relationship between DNA cytosine methylation and the expression of two genes associated with resistance to DNA methylation damage. Variants of RajiMex- cells acquired resistance to N-methyl-N-nitrosourea by either reactivating a previously silent O6-methylguanine-DNA methyltransferase (MGMT) gene or by repressing the hMSH6 mismatch repair gene. DNA sequencing and measurements of mRNA and enzyme levels revealed that MGMT activity was not correlated with methylation of the core MGMT promoter. Treatment with the demethylating agent 5-azadeoxycytidine reduced MGMT mRNA and enzyme levels, indicating that methylation of some nonpromoter sequences may be required for MGMT gene expression. In contrast, both hMSH6 mRNA and protein levels were increased by 5-azadeoxycytidine treatment of an N-methyl-N-nitrosourea-resistant variant that did not express detectable hMSH6, which implies that this gene was transcriptionally silenced by cytosine methylation. This could be substantiated by in vitro modification of the CpG sites in the hMSH6 promoter with restriction methylase M.SssI, which abolished the transcription of a reporter gene under its control in a transient transfection assay. Taken together, our data show that treatment with chemical methylating agents alters gene expression patterns through increased CpG methylation of genomic DNA, and thereby permits the emergence and selection of clones that are resistant to these agents due to increased repair or tolerance of O6-methylguanine.

Influence of LY 300164, an antagonist of AMPA/kainate receptors, on the anticonvulsant activity of clonazepam.

LY 300164 [7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo(4, 5H)-2,3-benzodiazepine], an antagonist of AMPA/kainate receptors, at 5 mg/kg exerted a significant anticonvulsant effect, as regards seizure and afterdischarge durations in amygdala-kindled seizures in rats. At lower doses, LY 300164 did not exert anticonvulsant activity. Clonazepam alone (0.003-0.1 mg/kg) significantly diminished seizure severity, seizure and afterdischarge durations. Coadministration of LY 300164 (2 mg/kg) with clonazepam (0.001 mg/kg) resulted in the significant anticonvulsant activity. Seizure severity score, seizure and afterdischarge durations were reduced from 5 to 4, from 32.6 s to 12.3 s, and 42.7 s to 23.2 s. LY 300164 (2 mg/kg), clonazepam (0.001-0.1 mg/kg) and the combination of clonazepam (0.001 mg/kg) with LY 300164 (2 mg/kg) did not affect long-term memory evaluated in the passive avoidance task in rats. LY 300164 (at the subprotective dose of 2 mg/kg) significantly potentiated the anticonvulsant action of clonazepam against maximal electroshock but not against pentylenetetrazol-induced convulsions in mice. The results indicate that blockade of glutamate-mediated events at AMPA/kainate receptors may differently affect the protection offered by clonazepam, which seems dependent upon the model of experimental seizures.

Reduced inhibitory effect of somatostatin on the exocrine function of the pancreas and on serum insulin (IRI) levels in chronic relapsing pancreatitis.

In 3 healthy men and 4 healthy women, and in 5 men and 2 women with confirmed chronic relapsing pancreatitis (CRP) the inhibitory effect of somatostatin cn pancreatic exocrine function and insulin secretion stimulated with pancreozymin and secretin was determined. In all 7 patients with CRP the volume of pancreatic juice and the bicarbonate and amylase and protein output after stimulation were lower than in healthy subjects, and somatostatin had a reduced inhibitory effect on both the basal secretion and particularly on the pancreozymin-secretin-stimulated secretion. A similarly lower inhibitory effect of somatostatin on the secretin-pancreozymin induced increase in blood insulin (IRI) level was observed in these patients. The presented data suggest that the damaged pancreas reacts less effectively not only to the stimuli enhancing its exocrine and endocrine secretory activity, but also to the stimuli inhibiting this activity. This observation may be of practical value for the evaluation of the functional efficiency of the pancreas.