Metabolic consequences of 5-year growth hormone (GH) therapy in children treated with GH for idiopathic short stature. Genentech Collaborative Study Group.

In a multicenter study the metabolic effects of 5 yr of GH therapy in children with idiopathic short stature were evaluated. Patients received 0.3 mg/kg.week recombinant human GH. Of the 121 patients who entered the study, data for 62 were analyzed at the final 5 yr point. Routine laboratory determinations were available for all 62 subjects at the 5 yr point. Special laboratory determinations, such as postprandial glucose and insulin, were available for only a subset of patients. Mean insulin-like growth factor I levels rose to 283 +/- 101 micrograms/L, within the normal range using age-appropriate reference standards. T4, cholesterol, triglycerides, blood chemistries, and blood pressure showed no significant changes during the 5-yr period. Mean baseline and 2-h postprandial glucose levels remained unchanged. Both fasting and postprandial insulin levels rose substantively from low normal levels to the normal range (median, 4.9-43 mU/L). Mean hemoglobin A1c levels remained within the normal range throughout the study. In summary, careful monitoring has not revealed any currently discernible metabolic side-effects of clinical significance after GH therapy in this 5-yr study of children with idiopathic short stature.

Graphite furnace atomic absorption spectrophotometric determination of 4-hydroxy-3-nitrobenzenearsonic acid, other organic arsenicals, and inorganic arsenic in finished animal feed.

4-Hydroxy-3-nitrobenzenearsonic acid (roxarsone) is administered in animal feed as a growth stimulant over a concentration range of 25-50 ppm. The drug is extracted from 5 g feed with 200 mL aqueous 1.0% ammonium carbonate solution and 5 min of mechanical shaking. Undissolved feed particles are allowed to settle and 1.0 mL aliquot of extract is diluted with 9.0 mL 15% methanol solution. This solution is subjected to sample atomization by a graphite furnace and arsenic detection by atomic absorption spectrophotometry (AAS). Roxarsone recovery from nonmedicated commercial feed fortified at 25 ppm was 103.6% with a relative standard deviation (RSD) of 4.0%. Recovery for 50 ppm fortification was 104.5% (RSD 4.3%). Roxarsone assay results by furnace AAS were compared with results by the current AOAC spectrophotometric method and the AOAC total arsenic method. Results by the 3 methods compare well. The procedure was also used to determine other organic arsenicals and inorganic arsenic in laboratory-fortified feed samples; these recoveries were essentially theoretical.

High pressure liquid chromatographic determination of nifursol in finished feeds.

Nifursol is extracted from feed with acetonitrile, and then washed with carbon disulfide to remove feed interferences. An aliquot is concentrated, diluted with 5% NaCl solution, filtered, and then subjected to high pressure liquid chromatography on a strong anion exchange column, using 365 nm photometric detection. The average recovery of nifursol from fortified feed samples was 100.6% with an average coefficient of variation of 3.5%. The nifursol determination is not subject to interference from the other commonly used nitrofurans.

Atomic absorption spectrophotometric determination of dibutyltin dilaurate in finished feeds: collaborative study.

Dibutyltin dilaurate is administered in the feed as an active drug for the removal of large roundworms, cecal worms, and several species of tapeworms from chickens and turkeys. The drug is extracted from finished feed with warm CHCl3, the CHCl3 extract is filtered, and a 25 ml aliquot is concentrated in the presence of methanol until all traces of CHCl3 are removed. The methanol solution is diluted and filtered to remove feed interferences, and then aspirated into an atomic absorption spectrophotometer with a triple-slot burner head, using an air/acetylene flame. The instrument response to tin at 286.3 nm is recorded. Recoveries of 100.5-101.9% tin were obtained for laboratory-prepared feeds. This method was collaboratively studied. The average recovery for dibutyltin dilaurate from 3 feed samples for 8 collaborators was 98.3% with an average coefficient of variation of 5.83%. The method has been adopted as official first action.

Atomic absorption spectrophotometric determination of 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone) in premixes.

Roxarsone (4-hydroxy-3-nitrobenzenearsonic acid) is extracted from the premix with aqueous 1% ammonium carbonate. The extract is filtered, diluted, and analyzed by atomic absorption spectrophotometry, using an air-acetylene flame and an arsenic electrodeless discharge lamp. The instrument response of the sample is compared to that of a standard solution of arsenic trioxide. Recoveries range from 99.7. to 100.4% and coefficients of variation range from 0.35 to 0.63%.

Gas-liquid chromatographic determination of nifursol in frozen turkey tissues to ten parts per billion.

Nifursol (3,5-dinitrosalicylic acid (5-nitrofurfurylidene) hydrazide) is extracted into ethyl acetate from 10 g tissue in the presence of sodium sulfate. Tissue interferences are removed from the tissue extract by washing with petroleum ether after the extract has been transferred into an aqueous solution by evaporation of ethyl acetate. The drug is hydrolyzed under acid conditions to form 5-nitro-2-furaldehyde (5NF). After partition of 5NF from the aqueous phase into benzene the extract is further cleaned up on a Florisil column. The 5NF is eluted from the Florisil column with benzeneethyl acetate. Electron capture gas-liquid chromatography of a 10 mul injection of the concentrated column eluate is the determinative step. Quantitation is accomplished by comparison of the peak height of the sample to the peak height of the standard which is carried through the method simultaneously. Studies of method performance on turkey muscle, liver, kidney, and skin tissues fortified to contain 10 ppb nifursol show a recovery range of 87.4-95.0% and a coefficent of variation range of 5.7-11.2%.