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Biomedical subjects

H M Solomon

Publications and source records attributed to H M Solomon.

At least 37 records · Page 2Linked to original sources
PubMed1994

Comparative effects of neutron irradiation and X irradiation on the embryonic development of the rat.

Our aim was to compare the dose-response relationship for the embryotoxic effects of 0.43 MeV neutrons with those of 240 kVp X rays after in utero exposures during early organogenesis in the rat. At 9.5 days after conception, pregnant rats were exposed to 0.025 to 0.35 Gy 0.43 MeV neutrons at a dose rate of 0.04 to 0.07 Gy/h. Comparable biological effects were produced using 0.50 to 2.05 Gy 240 kVp X rays. Neutron irradiation produced a greater proportion of offspring with very low body weight than with malformations when compared to X rays. There were no embryotoxic effects observed at neutron exposures of 0.025, 0.049, 0.079, 0.10, 0.15 and 0.20 Gy or X-ray exposures of 0.50 and 0.96 Gy. Taken together, the results suggest that the mechanisms by which neutron irradiation affects embryonic development may, in part, be both quantitatively and qualitatively different from those by which X irradiation affects development. These results support the generalization that the embryo exhibits a nonlinear response to increasing doses of ionizing radiations during the period of early organogenesis.

Abnormalities, Radiation-Induced↗
PubMed1994

Effects of dose and dose protraction on embryotoxicity of 14.1 MeV neutron irradiation in rats.

The embryotoxic effects of neutron radiation on rodent embryos are documented, but there is disagreement about the dose-response relationship and the impact of protracting the dose. Pregnant rats were exposed to total absorbed doses of 0.15 to 1.50 Gy 14.1 MeV neutrons on day 9.5 after conception, coincident with the most sensitive stage of embryonic development for the induction of major congenital malformations. In general terms, the incidence of embryotoxic effects increased with increasing total absorbed dose. However, the dose-response relationship differed depending on the parameter of embryotoxicity chosen, namely, intrauterine death, malformations or very low body weight. In a second study, embryos were exposed to a single embryotoxic absorbed dose (0.75 Gy) administered at a range of dose rates, from 0.10 to 0.50 Gy/h. The results offer no evidence that protraction of this selected dose significantly increased or decreased the incidence or pattern of embryotoxicity of the neutron exposure used in this study. The results do not support the hypothesis of a linear dose-response relationship for the effects of prenatal neutron irradiation that contribute to embryotoxicity for total absorbed doses of 0.15 to 1.50 Gy.

Abnormalities, Radiation-Induced↗
PubMed1993

Methyl methacrylate: inhalation developmental toxicity study in rats.

Methyl methacrylate (99.9% pure) was administered by vapor inhalation exposure to five groups (27 rats/group) of presumed pregnant rats (Crl:CD) at concentrations of 0 (control), 99, 304, 1,178, and 2,028 ppm for 6 hr/day on days 6-15 of gestation (G). Maternal body weight, feed consumption, and clinical signs were recorded throughout gestation. Dams were euthanized on day 20 G. Each uterus was weighed and corpora lutea, implantation sites and resorptions were counted. The number of fetuses per litter were counted and their location within the uterus recorded. All fetuses were weighed, sexed and examined for external and skeletal alterations. One half of the fetuses from each litter were examined for visceral alterations. No treatment-related deaths were noted at any concentration tested. Treatment-related effects on maternal body weight and feed consumption were noted at all exposure levels. The decreases in maternal body weight at 99 and 304 ppm were minimal and transient since they returned to control values by the next weighing period. When exposure was discontinued, body weight gain and feed consumption in all exposure groups returned to control values. There were no treatment-related changes in the number of litters produced or in the mean number per litter of corpora lutea, implantations, resorptions, live or dead fetuses, or sex ratio. Fetal body weights were similar between the control and treated groups. There were no treatment-related increases in the type or incidence of external, visceral, or skeletal malformations, developmental variations, or variations indicative of retarded development. Exposure to methyl methacrylate concentrations up to 2,028 ppm resulted in no embryo or fetal toxicity or malformations even at exposure levels that resulted in maternal toxicity.

Administration, Inhalation↗
PubMed1992

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International System of Units↗
PubMed1992

Rapid diagnosis of Brucella melitensis in blood: some operational characteristics of the BACT/ALERT.

A clinical isolate of Brucella melitensis was detected in a blood culture with the BACT/ALERT after an incubation period of 2.8 days. Dilution studies revealed an inverse linear relationship between the log of the initial concentration of the organism and the time to detection of a positive result. Reproducibility studies demonstrated a mean detection time of 48 +/- 1 h in 8 of 10 replicates seeded with a stock containing 10(2) CFU/ml.

Adult↗
PubMed1991

Developmental toxicity of dimethylacetamide by inhalation in the rat.

Dimethylacetamide (DMAC) is a widely used industrial solvent. It has been reported to be teratogenic when given to rats by injection or following dermal application. Most of these studies employed large single doses and did not examine both the fetal and the maternal response. In this study, groups of pregnant Crl:CD rats were exposed to 32, 100, or 282 ppm DMAC by inhalation for 6 hr/day from Days 6 through 15 of gestation (day on which copulation plug was detected was termed Day 1G). A control group of chambered pregnant rats was exposed simultaneously to air only. All female rats were euthanized on Day 21G. At 282 ppm, both maternal weight gain during the exposure period and fetal weight were significantly decreased and accompanied by a significant dose-response trend. These effects were not seen in rats inhaling either 32 or 100 ppm. Fetal resorptions were not increased in any of the groups exposed to DMAC. Fetal incidences of external, visceral, or skeletal variations and malformations were similar between the test and control groups. Therefore, both fetal and maternal toxicity were noted at 282 ppm and the no-observed adverse-effect level under these experimental conditions was 100 ppm for both the dam and the conceptus. DMAC was not demonstrated to produce malformations in the rat fetus even at a level that was toxic to the dam.

Abnormalities, Drug-Induced↗
PubMed1985

Quantitative buffy coat analysis. A hematologic screen applicable to the selection of apheresis donors.

Quantitative buffy coat analysis was performed on samples of venous blood with the QBC (Clay Adams Division of Becton Dickinson, Rutherford, NJ) Hematology System and the results for platelet counts, white blood cell counts, and microhematocrits were compared with those obtained by reference methods. At the established cut-off, values for apheresis donors the with-in run reproducibility (CV) of the platelet count was 6.8%; of the white blood cell count, 8.6%; and of the microhematocrit, 1.75%. Over the range of values studied, the platelet count showed the poorest correlation with the reference method (R = 0.72023) and the greatest dispersion of QBC values at a given reference value. Correlation coefficients for QBC and reference methods for white blood cell counts and hematocrits were 0.88887 and 0.89778, respectively. Predicted ranges of reference values for platelet counts and white blood cell counts, based on QBC measurements, were too wide at lower levels of the normal range to be clinically meaningful. When used in a screening mode to determine if results from apheresis donors exceeded specific cut-off values, the QBC system performed well as determined by high predictive values for results above the selected cut-offs. Misclassification errors with the QBC system were more likely to result in rejection of acceptable donors than acceptance of those with low platelet or white cell counts.

Blood Cell Count↗
PubMed1977

Collaborative study of a method for the detection of Clostridium botulinum and its toxins in foods.

The mouse toxicity and protection technique for the detection and identification of Clostridium botulinum and its toxins in foods was collaboratively studied by 11 laboratories. Each laboratory received 4 samples of cream of mushroom soup; 2 contained spores and toxin of C. botulinum type A, 1 contained spores and toxin of C. botulinum type E, and 1 contained spores of C. sporogenes. The media used were cooked meat medium (beef heart or chopped liver broth) and trypticase peptone glucose yeast extract broth with trypsin. The results indicate that this method has a high degree of repeatability and reproducibility. All 11 laboratories correctly identified the toxins and the nontoxic sample in the food and detected and identified the viable spores in the samples by means of the subsequent cultures. This method has been adopted as official first action.

Biological Assay↗
PubMed1977

Quantitative gas-chromatographic flame-ionization method for chloramphenicol in human serum.

We describe a flame-ionization gas-chromatographic procedure for determination of the potentially toxic antibiotic, chloramphenical, in serum. The serum (500 mul) is extracted into ethyl acetate and nonpolar impurities are subsequently partitioned into hexane. The drug is chromatographed as its bis-trimethylsilyl derivative, with the analog thiamphenicol as the internal standard. Within-run precision (CV) is 4.4% at a serum concentration of 41 mg/liter and 9.2% at a concentration of 5 mg/liter. Over a six-month period, the run-to-run variation was 5.1% at 40 mg/liter (n = 24). Results by the gas-chromatographic method compared well with those by an established colorimetric procedure; mean concentrations for the comparison samples in the two procedures were 18.4 mg/liter and 17.6 mg/liter, respectively (n = 27), with a coefficient of correlation of 0.998. The gas-chromatographic method is more precise and specific than classical microbiological procedures and is suitable for routine therapeutic monitoring of serum chloramphenicol concentrations.

Chloramphenicol↗
PubMed1977

Micro-scale anticonvulsant assay with use of nitrogen/phosphorus detector and on-column methylation compared with a macro-scale procedure involving flame-ionization detection.

We report a modified micro-scale gas-chromatographic procedure for determining phenobarbital, primidone, and diphenylhydantoin in serum with use of a nitrogen/phosphorus detector. Serum, 20 mul, is extracted into chloroform, the solvent is evaporated, and the residue dissolved in dilute (32 mmol/liter) trimethylanillinium hydroxide, which yields the methyl-derivatives of the drugs upon on-column injection. Within-run precision (CV) for the three drugs was 1.0, 2.1, and 1.4+, respectively, at concentrations of 19.2, 13.2, and 18.9 mg/liter; run-to-run precision at these concentrations was 4.4, 3.8, and 2.8%. Comparison of the 20-mul micro-scale procedure (y) with our conventional, flame-ionization macro-scale procedure (x), in which on-column methylation is used and which requires 1 ml of serum, gave the following respective results: y = 1.01 X -- 0.16 mg/liter, r = 0.992, y = 1.02 X + 0.29 mg/liter, r = 0.973; and y = 0.96x + 0.04 mg/liter, r = 0.996.

Anticonvulsants↗
PubMed1976

Kinetic determination of serum haptoblobin with a centrifugal analyzer.

We describe a method for determining haptoglobin with a centrifugal analyzer that is based on haptoglobin combining stoichiometrically with hemoglobin to form a complex that has peroxidase-like activity proportional to the quantity of haptoglobin present. Under assay conditions, unbound hemoglobin exhibits only a small fraction of the total peroxidase activity. Activity is measured colorimetrically at 405 nm after reaction with o-dianisdine and ethyl hydrogen peroxide. The procedure is standardized by saturating aknown amount of hemoglobin with a serum whose hemoglobin binding capacity exceeds the amount of hemoglobin in the assay system. The mean and mean within-run precision of our method, determined by performing 17 replicate assays of both a pooled normal serum and a 10-fold dilution of the serum, was 1.13 g/liter (CV, 2.9%), and 106 mg/liter (cv, 5.8%), respectively. The 95 percentile estimate of the normal range by our method is 0.45-1.85 g/liter hemoglobin binding capacity. When results by our automated method were compared to those by a manual method [Scand. J. Clin. Lab. 2nvest. 18, 80 (1965)], the slope of the unweighted linear least-squares regression line was .970 the y-intercept 26 mg/liter, and the correlation coefficient .995.

Autoanalysis↗
PubMed1976

Gas-chromatographic micro-scale procedure for theophylline, with use of a nitrogen-sensitive detector.

We report a micro-scale procedure for determination of theophylline by use of gas chromatography with nitrogen-sensitive detection. The procedure requires only 10 mul of serum, plasma, or saliva. This sample size makes the determination especially appropriate for monitoring in a pediatric population. With the sample volume used, background interference is equivalent to about 0.1 mg/liter and 0.5 mg of theophylline per liter can easily be measured. The new method correlates well with our earlier flame ionization gas-chromatographic procedure that required 1 ml of sample [Clin. Chem. 21, 1038 (1975)]. The selectiviey of the nitrogen detector allows a simplified extraction procedure. Between-run precision (CV) is 2.8% at a theophylline concentration of 14.8 mg/liter.

Caffeine↗
PubMed1976

Gas-chromatographic determination of 5-fluorocytosine in human serum.

We describe a sensitive and precise gas-chromatographic method, in which cytosine is used as the internal standard, for determination of an antifungal agent, 5-fluorocytosine, in serum. The trimethylsilyl derivative of this drug is well separated from the internal standard and from normal serum constituents. Amphotericin B does not interfere with the determination of 5-fluorocytosine. The lower limit of detection for 5-fluorocytosine is 1 mg/liter when 200 mul of serum is analyzed. Within-run precision (CV), established by analysis of 10 replicates, was 4.5% at a concentration of 19.9 mg/liter. Twenty-five serum samples were analyzed for 5-fluorocytosine by a microbiological assay and by the gas-chromatographic method. Mean value observed with the bioassay was 78.5 mg/liter and with our procedure was 69.4 mg/liter. When values for our assay were regressed against values for the bioassay, slope of the least-squares line was 0.85, intercept was 2.7 mg/liter, and r was 0.93.

Chromatography, Gas↗