Utility of systemic voriconazole in equine keratomycosis based on pharmacokinetic-pharmacodynamic analysis of tear fluid following oral administration.

OBJECTIVE: To clarify the detailed pharmacokinetics (PK) of orally administered voriconazole in tear fluid (TF) of horses for evaluating the efficacy of voriconazole secreted into TF against equine keratomycosis. ANIMALS STUDIED: Five healthy Thoroughbred horses. PROCEDURES: Voriconazole was administrated through a nasogastric tube to each horse at a single dose of 4.0 mg/kg. TF and blood samples were collected before and periodically throughout the 24 hours after administration. Voriconazole concentrations in plasma and TF samples were analyzed using liquid chromatography-electrospray tandem-mass spectrometry. The predicted voriconazole concentration in both samples following multiple dosing every 24 hours was simulated by the superposition principle. RESULTS: The mean maximum voriconazole concentrations in plasma and TF were 3.3 µg/mL at 1.5 h and 1.9 µg/mL at 1.6 h, respectively. Mean half-life in both samples were 16.4 and 25.2 h, respectively. The ratio of predicted AUC0-24 at steady state in TF (51.3 µg∙h/mL) to previously published minimum inhibitory concentration (MIC) of Aspergillus and Fusarium species was >100 and 25.7, respectively. CONCLUSIONS: This study demonstrated the detailed single-dose PK of voriconazole in TF after oral administration and simulated the predicted concentration curves in a multiple oral dosing. Based on the analyses of PK-PD, the simulation results indicated that repeated oral administration of voriconazole at 4.0 mg/kg/d achieves the ratio of AUC to MIC associated with treatment efficacy against Aspergillus species. The detailed PK-PD analyses against pathogenic fungi in TF can be used to provide evidence-based medicine for equine keratomycosis.

Molecular cloning and characteristics of a novel zinc finger protein and its splice variant whose transcripts are expressed during spermatogenesis.

Testicular zinc finger protein (TZF) has a zinc finger motif of the Cys2-His2 type and its transcript is expressed predominantly in mouse spermatogenic cells. Using the fragment of TZF as a probe, we isolated the alternative splice variant form (TZF-L) from mouse testis cDNA library. Analysis of the open reading frame of each cDNA indicated that TZF and TZF-L were polypeptides of 942 and 2025 amino acid residues, respectively, and the N-terminal 902 amino acids of TZF-L were identical to those of TZF. The C-terminal region of TZF-L had more a zinc finger motif of the Cys2-His2 type and poly-Glu and poly-Pro regions. The mouse TZF/TZF-L gene spanned >20 kb and consisted of 11 exons. RT-PCR analysis of the expression level of mRNAs for mouse TZF and TZF-L showed that both transcripts are highly expressed in testis and moderately in kidney and ovary. Elevated expression of both transcripts during testicular development in mice was restricted to spermatocytes at the pachytene stage of meiotic prophase. Fusion proteins with GFP also demonstrated the nuclear localization of TZF and TZF-L. These experiments suggest that TZF and TZF-L may act to control the gene activity during spermatogenesis.