Pyrimethamine levels in sera, cerebrospinal fluid(CSF), and ventricular fluid were measured by using reversed-phase high-pressure liquid chromatography. The specimens were from 37 infants receiving pyrimethamine for treatment of suspect or proven congenital toxoplasmosis. Pyrimethamine half-life in serum was 64 ± 12 h when determined by study of terminal-phase kinetics of samples obtained from nine babies. This half-life was significantly different (P = 0.008) from the pyrimethamine half-life (33 ± 12 h) determined by terminal-phase kinetics for two babies of the same age taking phenobarbital. Serum pyrimethamine levels at various intervals after dosages of pyrimethamine were also lower for infants receiving phenobarbital. Levels measured in sera from babies taking the same dose of pyrimethamine throughout their first year of life did not appear to vary significantly over time or at different ages (P > 0.05). Mean + standard deviation serum levels 4 h after a pyrimethamine dose were 1.297 ± 0.54 pg/ml for babies taking 1 mg of pyrimethamine per kg of body weight daily and 0.7 + 0.26 ,ug/ml for babies taking 1 mg/kg each Monday, Wednesday, and Friday. Levels in CSF were approximately 10 to 25% of concomitant levels in serum. Serum folate levels for infants who took 0.64 to 1.7 mg leukovorin per kg ranged from 33 to 663 ng/ml. To determine whether the levels of pyrimethamine in serum and CSF of treated infants were in a range that affected the most virulent, rapidly replicating, and standard laboratory strain of Toxoplasma gondii, effects of various concentrations of pyrimethamine and sulfadiazine on replication of T. gondii in vitro were assessed. The levels of the antimicrobial agents effective in vitro were in the range of levels of pyrimethamine achieved in sera and CSF. Although folinic acid could inhibit the therapeutic effect of pyrimethamine and sulfadiazine in vitro, inhibition was noted only at levels (.4,800 ng/ml) that were considerably higher than the folate levels found in the treated infants' sera.Pyrimethamine is a critical part of therapy for babies with congenital toxoplasmosis (15). It is also important in therapy of infants with human immunodeficiency virus infection who also have toxoplasmic encephalitis (16). Data concerning pharmacokinetics of this agent in infants and children are greatly needed, as there are no data available to guide rational selection of pyrimethamine dosage for such patients. MATERIALS AND METHODSPatients and sampling strategy. Sera were obtained from infants between the ages of 10 days and 1.5 years. The infants were receiving pyrimethamine for treatment of suspect or definite congenital toxoplasmosis. These sera were obtained in accordance with National Institutes of Health guidelines concerning human subjects, which includes informed consent from parents and guardians. In some instances, when cerebrospinal fluid (CSF) or cerebral ventricular fluid were available, these samples were also studied. In the feasibility phase of this study a recommendation was * Correspond...

Reasons for performing study: Intracytoplasmic sperm injection (ICSI) is used to produce foals from otherwise infertile mares and from stallions with limited sperm stores, but requires expensive equipment and is technically demanding. Methods to transport oocytes to ICSI laboratories would allow collection of oocytes by the referring veterinarian and enable greater application of this technique. Objectives: This study was conducted to evaluate protocols that could be used to transport immature and maturing oocytes for ICSI. Study design: In vitro experiment. Methods: Oocytes were recovered by transvaginal ultrasound-guided follicular aspiration either from dominant follicles 24 h after deslorelin administration (dominant stimulated follicle [DSF]), or from subordinate (immature) follicles at the same time. To mimic transport, DSF oocytes were incubated overnight under differing conditions before ICSI; immature oocytes were placed in varying conditions overnight before in vitro maturation, followed by ICSI. The rate of blastocyst production was compared among treatments. Results: Blastocysts were produced in all groups. Dominant stimulated follicle oocytes held in sealed tubes in pre-equilibrated control maturation medium maintained at 37°C yielded blastocyst development equal to that obtained for control incubated oocytes (70%). Dominant stimulated follicle oocytes held similarly in a warm passive device yielded poor blastocyst development (10%). Immature oocytes held for one or 2 nights in modified M199 medium, or for one night in commercial embryo holding solution, in air at room temperature, yielded 35-37% blastocyst development per injected oocyte. Conclusions: A commercially available medium can be used for shipping immature oocytes at room temperature with good resulting blastocyst rates. Better blastocyst rates per oocyte are obtained from DSF oocytes; however, these require maintenance at 37°C and as they are already maturing at the time of collection, are more sensitive to delays. This new, practical information supporting transport of both immature and DSF oocytes for ICSI may allow wider use of this procedure.

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Optimising the developmental potential of immature equine oocytes and invitro-produced (IVP) embryos was explored through modifications of established media and holding temperature. In Experiment 1, delaying spontaneous resumption of meiosis through the process of simulated physiological oocyte maturation with the addition of the adenylate cyclase activator forskolin (50µM) and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (100µM) to overnight holding medium before maturation improved blastocyst production (P<0.05). In Experiment 2, the blastocyst production rate was increased significantly when cumulin (100ng mL−1) was added to the overnight holding or culture media (P<0.05). In Experiment 3, immature oocytes held overnight at 16°C before maturation had improved developmental competence than those held at 20°C and 5°C (P<0.05). There was no difference between maturation rates, but blastocyst formation per cleaved oocyte was significantly greater in oocytes held overnight at 16°C than at 20°C or 5°C. Furthermore, blastocyst formation per recovered oocyte and per fertilised oocyte was greater when oocytes were held before maturation at 16°C than at 5°C (P<0.05). In Experiment 4, the addition of sodium ascorbate (AC; 50µg mL−1) to the maturation and/or culture media of oocytes and IVP embryos did not improve blastocyst production, but did appear to lower cleavage rates compared with oocytes and embryos cultured without AC.