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Dive into the research topics where Earl B. Dawson is active.

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Featured researches published by Earl B. Dawson.


Fertility and Sterility | 1992

Effect of ascorbic acid supplementation on the sperm quality of smokers.

Earl B. Dawson; William A. Harris; Melvin C. Teter; Leslie C. Powell

OBJECTIVE To determine the effect of ascorbic acid supplementation on the sperm quality of heavy smokers. DESIGN Microscopic examination of semen for 1 month during supplementation with placebo or ascorbic acid at dose levels of 200 or 1,000 mg/d. SETTING Department of Obstetrics and Gynecology, The University of Texas Medical Branch. PARTICIPANTS Seventy-five men (20 to 35 years old) randomly divided into one of three supplementation groups: placebo, 200 mg and 1,000 mg of ascorbic acid. MAIN OUTCOME Improvement in sperm quality as compared with presupplementation levels and between the three treatment groups. RESULTS The placebo group showed no improvement in sperm quality. The groups receiving ascorbic acid showed improvement in sperm quality with most improvement in the 1,000-mg group. Pearsons correlation showed statistically significant relationships between the weekly group means of serum and seminal plasma ascorbic acid levels and sperm qualities. CONCLUSIONS Ascorbic acid supplementation of heavy smokers in excess of 200 mg/d results in improved sperm quality.


Biological Trace Element Research | 1998

COMPARISON OF SPERM VIABILITY WITH SEMINAL PLASMA METAL LEVELS

Earl B. Dawson; Sherry Ritter; William A. Harris; Douglas R. Evans; Leslie C. Powell

This study compares the semen levels of lead (Pb), cadmium (Cd), and aluminum (Al) in relation to live sperm in semen samples from 64 apparently healthy men. The measured levels were separated into live sperm count tertiles (<25% [18 subjects], 25–50% [26 subjects], and >50% [20 subjects]). The mean ± SD for each group was calculated, and the difference between the means of the high and low tertiles were compared by ANOVA. Significant differences were observed between the high and low live sperm groups for Pb (p < 0.01) and Al (p < 0.05), but not Cd. Spearman’s rank correlation between sperm viability and the semen plasma metal levels showed a direct relation to Mg (p < 0.05). However, there was an inverse relation to lead (p < 0.001), cadmium (p < 0.01), and aluminum (p < 0.01). There was no significant correlation between Ca and Zn. Linear regression between the live sperm counts and semen level of the three metals show that metal levels were inversely correlated with the percentage of live sperm (p < 0.001, <0.01). Apparently, the presence of these metals in the environment and in seminal plasma exerts a toxic effect on sperm.


Journal of The American College of Nutrition | 1999

The Effect of Ascorbic Acid Supplementation on the Blood Lead Levels of Smokers

Earl B. Dawson; Douglas R. Evans; William A. Harris; Melvin C. Teter; William J. McGanity

BACKGROUND The study subjects were 75 adult men (20 to 30 years of age), who smoked one pack of cigarettes per day (minimum) and had no clinical signs of ascorbic acid deficiency or lead toxicity. None had a history of industrial exposure to lead, and the blood-lead levels were anticipated to be below 1.45 micromol/L, the minimum blood level associated with toxicity symptoms. METHODS The men were randomly assigned to three study groups of 25, and each group was provided a four-week supply of one level of daily ascorbic acid supplements (placebo, 200 mg or 1000 mg of ascorbic acid). We measured baseline and weekly serum and urine ascorbic-acid levels as well as blood and urine lead levels. The weekly group means and variations of the measured data were statistically compared by means of ANOVA and Pearsons correlation. RESULTS The serum ascorbic-acid levels of the groups receiving ascorbic acid increased significantly after one week (p< or =.001). There was no effect of placebo or 200 mg ascorbic-acid supplementation on the blood or urine lead levels. However, there was a 81% decrease in blood-lead levels in the 1000 mg ascorbic acid group after one week of supplementation (p< or =.001). CONCLUSIONS Daily supplementation with 1000 mg of ascorbic acid results in a significant decrease of blood-lead levels associated with the general population. Ascorbic acid supplementation may provide an economical and convenient method of reducing blood-lead levels, possibly by reducing the intestinal absorption of lead.


Fertility and Sterility | 1979

Apparent Effect of Ascorbic Acid Medication on Semen Metal Levels

William A. Harris; Thaddeus E. Harden; Earl B. Dawson

The apparent effect of ascorbic acid therapy for nonspecific spermagglutination on semen levels of ascorbic acid as well as macro- and micrometals was determined in 20 men (ages 25 to 38). Pretreatment diagnosis was based on infertility and relatively low ratings in sperm density, motility, motility index, and semen volume, and were associated with large numbers of abnormal sperm, sperm precursors, and leukocytes. The pretreatment levels of ascorbic acid, sodium, iron, potassium, zinc, manganese, lead, magnesium, and copper were measured in each patients semen and compared with levels following 60 days of dietary vitamin C supplementation (1.0 gm/day). Analysis of the vitamin C preparation prescribed revealed that each subject was given an impure ascorbic acid medication to supplement a normal diet. Therefore, the significant increases in levels of ascorbic acid and metals in semen following therapy could not be attributed to ascorbic acid alone, nor, similarly, the improved physical parameters of each subjects semen following therapy; no apparent spermagglutination and restored fertility may be due to the interaction of ascorbic acid with cations found in semen.


Archives of Environmental Health | 1999

Third-Trimester Amniotic Fluid Metal Levels Associated with Preeclampsia

Earl B. Dawson; Douglas R. Evans; John Nosovitch

Studies of maternal amniotic fluid and serum at delivery have revealed the presence of toxic metals or deficiencies of essential metals associated with high-risk pregnancy. Essential and toxic metal levels were studied in 29 preeclamptic and 101 normal pregnancies. The authors grouped the samples according to the following gestation ages: 33-36 wk (48 normal and 10 preeclamptic) and 37-40 wk (53 normal and 19 preeclamptic). The metals studied were calcium, magnesium, zinc, selenium, copper, cadmium, and lead. Comparisons of the 33-36-wk gestation group showed significant differences between normal and preeclamptic amniotic fluid in levels of lead, calcium, magnesium, zinc, and selenium. There were also significant differences in levels of magnesium, copper, zinc, cadmium, and lead during the gestation period of 37-40 wk. The changes observed in calcium and lead levels were consistent with the results of animal studies in which investigators have found depressed calcium transport associated with subacute or chronic lead poisoning, resulting in a physical syndrome similar to preeclampsia.


Clinical Toxicology | 1982

Effects of Hemodialysis and Dimercaprol in Acute Dichromate Poisoning

Eileen N. Ellis; Ben H. Brouhard; Robert E. Lynch; Earl B. Dawson; Ronald Tisdell; Myron M. Nichols; Felix Ramirez

A 22-month-old infant died after ingesting sodium dichromate his father had brought from work. Treatment included folic acid and dimercaprol administration, hemodialysis, and exchange transfusion. To evaluate this treatment, four dogs were hemodialyzed after receiving intravenous sodium dichromate: their dialyzer chromate clearance was similar to their renal chromate clearance and their dialyzer chromate clearance was not significantly different before or after dimercaprol administration. This and other cases in the literature indicate that although chromate poisoning is often fatal, supportive care, forced diuresis, and chelating agents may be helpful. Hemodialysis may be required if renal failure occurs. Awareness of toxicity and prevention remain the most important approaches.


Biological Trace Element Research | 2000

Seminal plasma trace metal levels in industrial workers.

Earl B. Dawson; Douglas R. Evans; William A. Harris; Leslie C. Powell

This study compares the seminal plasma trace metal levels of hospital workers with groups of industrial workers in a petroleum refinery, smelter, and chemical plant. The metals measured were the essential metals (copper, zinc, nickel, cobalt, and manganese) and the toxic metals (lead, cadmium, and aluminum). The group mean±SE metal level for each group (50 subjects per group) was calculated, and the statistical significance of the group mean differences of the industrial groups with the hospital group (control) was determined by the Student’s t-test.The differences observed in the smelter group were increased copper and zinc (p≤0.001) and decreased nickel, cobalt, and manganese (p≤0.001,≤0.01). The refinery group differences were increased copper, zinc, and nickel (p≤0.001) but decreased cobalt and manganese (p≤0.001). The chemical group differences were increased zinc (p≤0.001) and decreased cobalt (p≤0.001). The seminal plasma levels of the toxic metals lead and aluminum were increased in each of the industrial groups (p≤0.001). Concurrent differences were (1) decreased accumulation of nickel, cobalt, and manganese in the smelter group, (2) decreased cobalt and managanese in the refinery group, and (3) only decreased cobalt in the chemical group.


American Journal of Obstetrics and Gynecology | 1969

Pregnancy in the adolescent

William J. McGanity; Harry M. Little; Ann Fogelman; Lequida Jennings; Evelyn Calhoun; Earl B. Dawson

Abstract Basic descriptive data concerning the obstetric, socioeconomic, educational, nutritional, and biochemical information have been obtained from over 800 adolescent pregnant women who sought prenatal care at the University of Texas Medical Branch Hospitals. The mean nutrient intake with the exception of calcium and iron met or exceeded the Recommended Dietary Allowances of the National Research Council (1964). Biochemical assessment revealed significant deprivation of iron, vitamins A and C, and riboflavin. Clear differences between nonwhite and white segments of the population were found in the hematologic levels. Implications are discussed for the educational, social, health, and related nutritional preparation of these young mothers in our community.


Biological Trace Element Research | 2000

Blood cell lead, calcium, and magnesium levels associated with pregnancy-induced hypertension and preeclampsia

Earl B. Dawson; Douglas R. Evans; Randall Kelly; James W. Van Hook

This study compares the red blood cell (Rbc) levels of lead (Pb), calcium (Ca), and magnesium (Mg) in relation to blood pressure in 39 pregnant women in the third trimester of pregnancy. The study population included 20 women with normal pregnancies, 15 with mild hypertension, and 4 with severe hypertension and preeclampsia. The mean±SD for each group was calculated and the difference between the means of the normotensive and the other groups were compared by analysis of variance. Significant differences from normal to the preeclamptic pregnancies were in (1) elevated Rbc Pb (p≤0.001), (2) lower Rbc Ca (p≤0.001), and (3) lower Rbc Mg/Pb ratio (p≤0.0001). Pearson’s rank correlation between blood pressure showed a direct relation to the Rbc Pb level (p≤0.01) and an inverse relation to the Rbc Ca and Mg/Pb ratio (p≤0.004,≤0.007). Apparently, prenatal blood pressure is directly proportional to Rbc Pb content and related or modified by Rbc Ca and Mg.


American Journal of Obstetrics and Gynecology | 1990

Vitamin E levels in premenstrual syndrome

C. James Chuong; Earl B. Dawson; Edward R. Smith

To determine whether changes in peripheral vitamin E levels are associated with symptoms of premenstrual syndrome, 10 patients with premenstrual syndrome and 10 control subjects were studied. They gave blood at 2- or 3-day intervals throughout three menstrual cycles. The vitamin E was measured by fluorometry after hexane extraction and luteinizing hormone was measured by radioimmunoassay. In the control group, vitamin E values were 854 +/- 45 micrograms/dl (mean +/- SE) during the luteal phase and 925 +/- 55 micrograms/dl during the follicular phase. No significant changes were noted between the two values. In the patients with premenstrual syndrome, the values were 849 +/- 53 micrograms/dl during the luteal phase, which was not significantly different from 858 +/- 48 micrograms/dl during the follicular phase. No significant changes were noted between the control group and the patients with premenstrual syndrome in either the luteal or the follicular phase. Vitamin E deficiency in patients with premenstrual syndrome was not shown by peripheral vitamin E levels in our study.

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William J. McGanity

University of Texas Medical Branch

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Douglas R. Evans

University of Texas Medical Branch

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Leslie C. Powell

University of Texas Medical Branch

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R.R. Clark

University of Texas Medical Branch

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C. James Chuong

University of Texas Medical Branch

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Edward R. Smith

Boston Children's Hospital

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Melvin C. Teter

University of Texas Medical Branch

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Chuong Cj

University of Texas Medical Branch

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H.A. Croft

University of Texas Medical Branch

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