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E H Allen

Publications and source records attributed to E H Allen.

At least 19 recordsLinked to original sources
PubMed1988

Californium-252 plasma desorption mass spectrometry of aminoglycoside antibiotics.

This paper presents mass spectral data of eleven aminoglycoside antibiotics by using californium-252 plasma desorption (252Cf PD) mass spectrometry. This mass spectral data could be used to develop a confirmatory method for monitoring aminoglycoside antibiotic residues isolated from food products of animal origin. Mass spectra were determined by applying time-of-flight 252Cf PD mass spectrometry to eleven aminoglycoside antibiotics, namely: neomycin, kanamycin, paromomycin, tobramycin, apramycin, streptomycin, dihydrostreptomycin, amikacin, netilmicin, sisomicin and gentamicins. All eleven antibiotics yielded positive ion spectra. These hydrophilic antibiotics were derivitized to extractable chromopheric compounds. All but two antibiotics (streptomycin and dihydrostreptomycin) yielded nitrophenyl derivatives and spectra were obtained in both negative and positive ion modes. Derivatized aminoglycosides produced cation and anion spectra with quasimolecular ions corresponding to [M + H]+., M+, [M - H]-., [M + Na]+, [M + K]+ and M-. or [M - H]- and M-. or [M - H]-. Underivatized antibiotics were best examined in the positive ion mode. 252Cf PD mass spectrometry consistently produced very strong molecular or quasimolecular ions for all aminoglycoside antibiotics.

Aminoglycosides↗
PubMed1986

Reducing the effect of chemiluminescence on the efficiency of extracting 14C-neomycin from fortified kidney tissue as measured by a liquid scintillation system.

Extraction efficiency was monitored, using 14C-neomycin and liquid scintillation counting, during development of a procedure to isolate neomycin from fortified kidney tissue. Chemiluminescence caused 119% false positive recovery at 0.16 ppm neomycin (1260 disintegrations/min (dpm) activity). However, the contribution of chemiluminescence to false positive recovery was negligible above 8 ppm neomycin (63,000 dpm activity). To reduce chemiluminescence, fortified kidney tissue was extracted with saline by homogenization, mixed with Protosol at 70 degrees C for 1 h, cooled 5 min at 4 degrees C and neutralized with acetic acid. The digest was mixed with Aquasol and incubated 1 h at 47 degrees C, followed by equilibration for 2 h in the counter. The procedure allows reliable monitoring of extraction efficiency down to about 407 dpm activity from 14C-neomycin (0.05 ppm) with maximum chemiluminescence of about 4%.

Animals↗
PubMed1983

Reference serum pepsinogen concentrations in dairy cattle.

Serum samples from 27 yearling heifers and 50 lactating cows were analyzed for pepsinogen concentration. Concentrations were 44 +/- 12 (SD) ng of pepsinogen/ml (2,200 mU of tyrosine/ml) of serum for the yearling heifers and 20 +/- 8 ng/ml (1,400 mU of tyrosine/ml) for the lactating cows. These initial data indicate that a yearling calf, grazing on pasture, with a serum pepsinogen concentration greater than 68 ng/ml (2,900 mU of tyrosine/ml) should be examined for ostertagiasis.

Animals↗
PubMed1982

Comparative pharmacokinetics of chlortetracycline in milk-fed versus conventionally fed calves.

Plasma and tissue concentration and pharmacokinetics of chlortetracycline (CTC) was determined in milk-fed and conventionally fed Holstein calves. A two-compartment open model was used after a single intravenous dose (11 mg CTC/kg body weight). There were no significant differences between dietary treatments. The drug was rapidly distributed from plasma into the peripheral compartment but was slowly eliminated, with detectable concentration of CTC continuing for 72 h after dosing. A single-compartment model was used after a single oral dose (22 mg CTC/kg body weight). All but four of the kinetic parameters were significantly different for the two dietary treatments. Milk-fed calves had a larger area under the plasma level curve, a larger fraction of the dose absorbed, a smaller volume of distribution and a smaller overall body clearance rate. Estimated recovery of CTC in the urine of the milk-fed calves was greater, regardless of route of administration. The concentration of CTC in tissues following an oral dose was greatest in kidney, followed by liver, heart, skeletal muscle, spleen and brain. Tissue depletion of CTC closely paralleled the decline in plasma concentration.

Administration, Oral↗
PubMed1982

Selected blood chemistry and hematologic characteristics in milk-fed and conventionally fed calves.

Effects of diet and age on selected blood chemistry and hematologic characteristics were studied in 20 Holstein bull calves. Milk-fed calves (treatment 1) were maintained exclusively on a milk-replacer diet. Conventionally fed calves (treatment 2) were provided a calf-starter diet and alfalfa hay beginning at 2 wk of age and were weaned from milk replacer at 7 wk of age. Blood samples were collected by jugular puncture from all animals just before the morning feeding at 6, 7, 9, and 11 wk of age. Milk-fed calves had greater glucose concentration in blood serum. Urea nitrogen of blood increased in conventionally fed calves from 6 through 11 wk and decreased in milk-fed calves. Hemoglobin concentration and packed cell volume decreased in calves receiving milk-replacer diet. Total protein and albumin concentrations were greater in the conventionally fed group. Treatment differences also existed for calcium and cholesterol concentrations and in alkaline phosphatase activity.

Aging↗
PubMed1982

Method for determining serum pepsinogen concentration, using pepsin standards and ultraviolet absorbance.

A simplification of the traditional hemoglobin methods for determining serum pepsinogen concentration was developed. In this method, 10% trichloroacetic acid solution was added to control samples, and hemoglobin substrate was added to controls and active enzyme samples; standards and samples were incubated for 18 hours, the proteins in the active tubes were precipitated with trichloroacetic acid and removed by filtration, and the absorbances of the supernatant of each standard and sample at 280 nm were measured. The major differences between this method and other methods for determining pepsinogen values are that the preacidification of serum with hydrochloric acid was eliminated, the incubation period was reduced to 18 hours (down from 24 hours), the relative pepsinogen concentration was determined by measuring the concentration of hydrolysis products, using ultraviolet, rather than visible absorbance, and a pepsin standard curve was used to determine the serum pepsinogen concentration. Comparison of freshly prepared pepsinogen and pepsin standard curves indicated that the pepsinogen preparations were slightly more active than the pepsin preparations (on a weight-to-weight basis) on the same substrate. Pepsin standards are used because they are more stable than pepsinogen standards. Three linear standard curve ranges were used: O 10 to 100, 50 to 300, and 100 to 500 ng of pepsinogen/ml of serum. The use of pepsin standard curves permits some variability of the incubation conditions without altering the results. For best results, the hemoglobin substrate solution should be prepared daily. This method may be useful in diagnosing ostertagiasis.

Animals↗
PubMed1978

The radiological changes in infections of the spine and their diagnostic value.

This study describes the early radiological changes which occur in infections of the spine, by examination of the initial radiographs in 45 patients with proven spinal infection. The commonest radiological change in infection of the spine was a symmetrical lesion involving the adjacent surfaces of two vertebrae, with a variable degree of reduction in height of the disc space. A paravertebral abscess was a common associated finding. No radiological pattern was completely reliable in distinguishing tuberculous from non-tuberculous infections, but in white patients the formation of new bone strongly suggested a pyogenic lesion. The presence or absence of a paravertebral abscess was not helpful in distinguishing the variety of infection.

Adolescent↗
PubMedDate not supplied

Dental treatment needs among hospitalized adult mental patients.

This survey determines the dental care needs of hospitalized adults with psychiatric and mental disorders. Comprehensive clinical and radiographic oral examinations, conducted on 33% of the patients in a large state mental hospital, found that extensive unmet needs existed in this population. The major requirements were for prophylaxis, calculus removal, and periodontal therapy. The patients' needs varied depending on several demographic factors, including length of hospitalization and psychiatric diagnoses.

Adult↗
PubMedDate not supplied

Determination of neomycin in animal tissues, using ion-pair liquid chromatography with fluorometric detection.

A liquid chromatographic (LC) method is described for the determination of neomycin in animal tissues. Tissues are homogenized in 0.2M potassium phosphate buffer (pH 8.0); the homogenate is centrifuged, and the supernate is heated to precipitate the protein. The heat-deproteinated extract is acidified to pH 3.5-4 and directly analyzed by LC. The LC method consists of an ion-pairing mobile phase, a reverse phase ODS column, post-column derivatization with o-phthalaldehyde reagent, and fluorometric detection. The LC method uses paromomycin as an internal standard, and separates neomycin from streptomycin or dihydrostreptomycin because they have different retention times. The LC column separates neomycin in 25 min; the detection limit is about 3.5 ng neomycin. The overall recovery of neomycin from kidney tissues spiked at 1-30 ppm was 96% with a 9.0% coefficient of variation. The method was also applied to muscle tissue.

Aminoglycosides↗
PubMedDate not supplied

Overview of physical-chemical methods for determining aminoglycoside antibiotics in tissues and fluids of food-producing animals.

A survey of literature is presented dealing with physical-chemical methods for the detection and quantitation of aminoglycoside antibiotics (gentamicin, streptomycin, dihydrostreptomycin, and neomycin) that are used in food-producing animals. Recent developments in cleanup and determinative procedures, particularly liquid chromatography, for these compounds in fluids and tissues are emphasized. Little research has been done on residues in tissues compared with other biological matrices. This review also covers the chemistry, general characteristics, tolerances, and withdrawal times for the approved uses of these antibiotics in animals that are used for food.

Aminoglycosides↗