Edwin A. Knecht
National Institute for Occupational Safety and Health
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Featured researches published by Edwin A. Knecht.
Reproductive Toxicology | 1995
James S. Kesner; Edwin A. Knecht; Edward F. Krieg
Urinary reproductive hormones afford specific and sensitive evaluation of female reproductive potential in epidemiologic and clinical settings. The goal of this study was to characterize the stability of urinary luteinizing hormone, follicle stimulating hormone, estrone 3-glucuronide, pregnanediol 3-glucuronide, and creatinine during storage as functions of time, temperature, and additives. After 2 weeks with no additives, activity of the four analytes, relative to initial concentrations, ranged from 91.9 to 102.8% at 4 degrees C, 35.1 to 89.6% at 25 degrees C, and 7.5 to 66.9% at 37 degrees C. Antimicrobial additives did not consistently improve stability. Analyte activity for samples stored with no additives for 24 weeks at -80 degrees C ranged from 69.0 to 101.2%. Glycerol and bovine serum albumin improved analyte stability; activity ranged from 91.1 to 106.3%. Other additives were ineffective. These results reveal conditions for storing reproductive hormone analytes in urine during epidemiologic field studies.
Steroids | 1994
James S. Kesner; Edwin A. Knecht; Edward F. Krieg; Georff Barnard; Heikki Mikola; Fortune Kohen; Mohamed Mutwahar Gani; John Coley
Competitive time-resolved fluoroimmunoassays (FIAs) were developed for measuring 1,3,5(10)-estratrien-3-ol-17-one glucosiduronate (estrone 3-glucuronide, E(1)3G) and 5 beta-Pregnane-3 alpha,20 alpha-diol 3-glucosiduronate (pregnanediol 3-glucuronide, Pd3G) in unextracted urine. The assays are specific, detect 0.98 ng E(1)3G/mL and 0.035 microgram Pd3G/mL, measure 102.8 +/- 2.0% of E(1)3G and 93.6 +/- 2.9% of Pd3G added, and exhibit between and within assay coefficients of variation, respectively, of 5.3% and 7.1% for E(1)3G and 6.8% and 7.8% for Pd3G. The urine matrix does not interfere with the assay. Urinary steroid glucuronide profiles measured by these FIAs conform to those of urinary steroid glucuronides and serum estradiol and progesterone measured by other established immunoassays. These FIAs afford the advantages of non-radioisotopic procedures and urine sample collection (convenience, non-invasiveness, integration of pulsatile secretion) to evaluate menstrual function in epidemiological, medical, and athletic populations.
Analytica Chimica Acta | 1994
James S. Kesner; Edwin A. Knecht; Edward F. Krieg
Abstract The goal of this effort was to develop and validate non-radioisotopic immunoassays for measuring luteinizing hormone and follicle stimulating hormone in unextracted urine. Towards this goal, commercial time-resolved immunofluorometric assays (IFMAs) were modified. Validation demonstrated that the resultant assays were specific, sensitive, accurate, and precise. Urine matrix was shown not to interfere with the assay. Gonadotropin profiles generated using these assays conformed to those measured in urine and serum by other established immunoassays. These IFMAs afford the collective advantages of non-radioisotopic procedures and urine sample collection (convenience, noninvasiveness, integration of pulsatile secretion), plus the superior sensitivity and specificity of IFMAs. Applications include epidemiology and medicine.
Journal of Occupational and Environmental Medicine | 2002
Elizabeth A. Whelan; Barbara Grajewski; Emily Wood; Lorna Kwan; Mimi Nguyen; Teresa M. Schnorr; Edwin A. Knecht; James S. Kesner
Flight attendants (FAs) may be at risk of adverse reproductive outcomes. We investigated the feasibility of biomonitoring studies in this mobile workforce. Forty-five female FAs and 26 female teachers (referents) collected daily urine and saliva samples for one menstrual cycle, provided daily diary data for approximately three months, and wore a wrist monitor to measure sleep disruption. A transport system enabled FAs to store samples while traveling. Overall, participation rates were low (37%) but of those recruited, over 90% of FAs and teachers completed the biomonitoring cycle. Data collection and sample integrity were not diminished by travel. Study methods resulted in good compliance and high quality data. It is possible to conduct studies of menstrual cycle function, sleep disruption, and circadian rhythm disruption in a mobile workforce potentially exposed to reproductive hazards.
Fertility and Sterility | 2002
Susan R. Reutman; Grace K. Lemasters; James S. Kesner; Rakesh Shukla; Edward F. Krieg; Edwin A. Knecht; James E. Lockey
OBJECTIVE To compare urinary levels of reproductive hormones in African American and Caucasian women. DESIGN Cross-sectional study. SETTING Ten United States Air Force (USAF) bases. PATIENT(S) African American (n = 33) and Caucasian (n = 65) women of reproductive age from a larger study of USAF women (n = 170). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Urinary endocrine end points: follicular luteinizing hormone (LH), preovulatory LH, level of LH surge peak, early follicular follicle stimulating hormone (FSH), follicular LH:FSH ratio, midluteal FSH, FSH rise before menses, early follicular estrone 3-glucuronide (E(1)3G), midfollicular E(1)3G, periovulatory E(1)3G peak, midluteal E(1)3G, early follicular pregnanediol 3-glucuronide (Pd3G), follicular Pd3G, rate of periovulatory Pd3G increase, E(1)3G:Pd3G on the day of luteal transition, slope of E(1)3G:Pd3G, and midluteal Pd3G. RESULT(S) Relative to Caucasians, African American women had significantly lower follicular phase LH:FSH ratios (mean +/- SD: 0.7 +/- 0.4 vs. 1.0 +/- 0.6), lower follicular phase Pd3G levels (1.0 +/- 0.5 vs. 1.2 +/- 0.8 microg/mg creatinine), and lower rates of periovulatory Pd3G increase (0.5 +/- 0.7 vs. 1.0 +/- 1.2 microg/mg creatinine). CONCLUSION(S) Findings of this analysis should be considered preliminary evidence of racial differences in hormone levels. Future studies are needed to determine whether these differences have clinical significance.
The Journal of Allergy and Clinical Immunology | 1988
Raymond E. Biagini; David I. Bernstein; J.S. Gallagher; William J. Moorman; Edwin A. Knecht; A.Wayne Smallwood; I. Leonard Bernstein
Four groups of four Macaca fascicularis monkeys were administered 10 consecutive weekly subcutaneous injections of 2 mg aluminum hydroxide plus one of the following: 200 micrograms of phthalic anhydride (PA)-monkey serum albumin (PA-MSA, group 1); 200 micrograms of PA dissolved in ethanol-saline (EtOH-sal, group 2); 200 micrograms of MSA (group 3); or EtOH-sal alone (group 4). Direct intracutaneous tests to PA-MSA, PA-EtOH-sal, MSA, and EtOH-sal were applied at biweekly intervals throughout the course of the immunization. Serum-specific IgG to PA-MSA and specific IgE to PA-MSA were determined at 2-week intervals according to the ELISA and RAST methods, respectively. The prevalence of cutaneous sensitivity to PA-MSA in the PA-MSA-immunized group (group 1) was significantly greater after 4 and 6 (p less than 0.01) and 8 and 10 (p less than 0.05) weeks, compared with the other treatment groups. Significantly elevated (p less than 0.01) PA-MSA-specific IgG was also observed in monkeys in group 1 compared with the other treatment groups. No significant changes in PA-MSA RAST or total IgE were observed in any group during the study. These results indicate that parenteral sensitization to PA in subhuman primates requires the presence of new antigenic determinants formed by PA on protein carriers.
Archives of Environmental Health | 1989
Raymond E. Biagini; William J. Moorman; Edwin A. Knecht; John C. Clark; I.L. Bernstein
Nine adult male Cynomolgus monkeys (Macaca fascicularis) were exposed for 10 min to 2.55 +/- 0.03 ppm formaldehyde (HCHO; mean +/- standard error of the mean, SEM) generated from formalin with a newly developed HCHO challenge system. The generation system was capable of producing highly stable HCHO vapor concentrations with fluctuations of HCHO concentrations of less than +/- 5%. The experimental design included pre-exposure methacholine challenge to determine if responses to HCHO were associated with pre-existing bronchial hyperreactivity. Significant changes in average pulmonary flow resistance (RL) were observed (compared to control RL values) at 2 (p less than 0.01), 5 (p less than 0.01), and 10 min (p less than 0.005) post-HCHO challenge. Pre-challenge RL values (mean +/- SEM) were 11.3 +/- 1.4 cm H2O.l/s, while at 2, 5, and 10 min after HCHO challenge, values were 16.1 +/- 2.1, 16.9 +/- 2.8 and 20.0 +/- 3.4 cm H2O.l/s, respectively. Methacholine challenge data suggest that reactions to HCHO tend to be greater in monkeys hyperreactive to methacholine, but the relationship does not reach statistical significance in this small series of animals. These data indicate that significant pulmonary function deficits occur immediately after challenge with 2.55 ppm HCHO vapor in monkeys.
Computers in Biology and Medicine | 1999
Edward F. Krieg; James S. Kesner; Edwin A. Knecht
An algorithm for detecting features of the cycles of the gonadotropic and ovarian hormones in women is described. The algorithm can detect hormone peaks and normal cycles defined in terms of the peaks in sequences of measurements that have an arbitrary starting point in the menstrual cycle and are of arbitrary length. The algorithm makes use of fuzzy set theory and is optimized using signal detection theory.
Environmental Health Perspectives | 2002
Susan R. Reutman; Grace K. Lemasters; Edwin A. Knecht; Rakesh Shukla; James E. Lockey; G. Edward Burroughs; James S. Kesner
Human Reproduction | 1998
James S. Kesner; Edwin A. Knecht; Edward F. Krieg; Allen J. Wilcox; John F. O'Connor