Prediction of serum ionized calcium concentration by use of serum total calcium concentration in dogs

OBJECTIVE: To determine whether total serum calcium (tCa) or adjusted tCa concentrations accurately predict ionized calcium (iCa) status in dogs. SAMPLE POPULATION: 1,633 canine serum samples. PROCEDURE: The tCa concentration was adjusted for total protein (TP) or albumin concentration by use of published equations. Correlations between iCa and tCa or adjusted tCa, tCa and TP, and tCa and albumin were calculated. Diagnostic discordance between tCa or adjusted tCa and iCa was determined. Diagnostic discordance in predicting iCa was also determined for 490 dogs with chronic renal failure (CRF). Sensitivity, specificity, positive and negative predictive values, and positive and negative diagnostic likelihood ratios were calculated for tCa, tCa adjusted forTP, and tCa adjusted for albumin. RESULTS: Diagnostic discordance was 27% when tCa concentration was used to predict iCa status. Use of adjusted tCa increased diagnostic discordance to approximately 37% for all dogs and 55% for dogs with CRF. Positive predictive value and positive diagnostic likelihood ratios were poor when tCa concentration was used to predict iCa status. The tCa concentration overestimated normocalcemia and underestimated hypocalcemia. Adjusted tCa overestimated hypercalcemia and underestimated hypocalcemia. CONCLUSIONS AND CLINICAL RELEVANCE: Adjusted tCa or tCa concentrations are unacceptable for predicting iCa status in dogs. Use of adjustment equations is not recommended. Direct measurement of iCa concentration is necessary for accurate assessment of calcium status. Use of tCa or adjusted tCa concentrations to predict iCa status in dogs could cause serious mistakes in diagnosis and case management, especially in dogs with CRF.     

In vitro germination of Paphiopedilum seed on a completely defined medium

Seed germination and seedling survival of Paphiopedilum cultured aseptically for 8 months in darkness or in the light varied with seed source, culture medium and incubation environment. In the light, germination was best and nearly equal on Burgeff EG-1, Thomale GD, and Norstog media, but more seedlings survived on Burgeff EG-1. Comparing incubation environments, the best germination and seedling survival occurred in the dark on either Norstog or Thomale GD, suggesting that increased production of Paphiopedilum from seed may require germination and early seedling growth in darkness. Since the Norstog medium is completely defined, it can be used to determine which organic constituents are vital for asymbiotic germination and growth of Paphiopedilum.     

Phloem transport of xenobiotics in Ricinus communis var. Gibsonii

Whole plants of Ricinus communis var. Gibsonii were used to study the mobility of some xenobiotics in the phloem. Solutions of ¹⁴C- or ³⁵S-labelled test compounds were introduced directly into the hollow petiole of a leaf that was exporting assimilates. Translocation was monitored by collecting phloem exudate from an incision in the stem bark beneath the treated leaf. Using [³H]sucrose as an internal standard, qualitative and quantitative results were obtained for a variety of model compounds, including herbicides, fungicides and a nematicide.     

Apple fruit-set: evidence for a specific role of seeds

An extract of immature Wealthy apple seeds, containing substances with gibberellin activity, was applied to unpollinated blossoms of the same variety, resulting in the production of mature seedless fruits. The implications with respect to the normal process of fruit-set are discussed.     

Residues of the insecticides phorate and methomyl in mint hay and oil

Since mint oil is used as a flavouring agent for foods and cosmetics, pesticide residues in the oil are undesirable. The residual behaviour of two pesticides, phorate and methomyl, was studied as replacements for chlorinated hydrocarbon pesticides which leave residues in the oil. Phorate applications of 1.1 kg/ha resulted in oil residues of 0.24 mg/kg total phorate in Oregon samples and 1.69 mg/kg in Washington samples. Less than 1% of the residues in the hay distilled with the oil. Mint oil undergoes a 100- to 1000-fold dilution in commercial use with a corresponding reduction of residues in the final product. No residues of methomyl were found in the oil, even with hay residues as high as 5.34 mg/kg. Residues in hay decreased to half of initial levels in 2 to 4 days, independently of use conditions. It was concluded that the proposed use of phorate or methomyl for control of mint pests does not present a residue hazard. Details of the analytical methods used are also presented.     

Survival of Phytophthora infestans in Surface Water

ABSTRACT Coverless petri dishes with water suspensions of sporangia and zoospores of Phytophthora infestans were embedded in sandy soil in eastern Washington in July and October 2001 and July 2002 to quantify longevity of spores in water under natural conditions. Effects of solar radiation intensity, presence of soil in petri dishes (15 g per dish), and a 2-h chill period on survival of isolates of clonal lineages US-8 and US-11 were investigated. Spores in water suspensions survived 0 to 16 days under nonshaded conditions and 2 to 20 days under shaded conditions. Mean spore survival significantly increased from 1.7 to 5.8 days when soil was added to the water. Maximum survival time of spores in water without soil exposed to direct sunlight was 2 to 3 days in July and 6 to 8 days in October. Mean duration of survival did not differ significantly between chilled and nonchilled sporangia, but significantly fewer chilled spores survived for extended periods than that of nonchilled spores. Spores of US-11 and US-8 isolates did not differ in mean duration of survival, but significantly greater numbers of sporangia of US-8 survived than did sporangia of US-11 in one of three trials.