Search PubMed⌕ Search

Biomedical subjects

B D Culver

Publications and source records attributed to B D Culver.

At least 19 recordsLinked to original sources
PubMed1999

Daily boron intake from the American diet.

Interest in boron as a naturally occurring trace element nutrient from the food supply is increasing. Mounting evidence suggests that boron is essential to human beings. This study explores the major food and beverage contributors of boron and estimates of daily boron intake from the American diet. Previous estimates in the literature of dietary boron consumption are based on limited foods and population segments. In this study we provide a more comprehensive assessment of boron consumption by the US population. A boron nutrient database of 1,944 individual foods was developed. These foods represent 95.3% by weight of all foods consumed in the US Department of Agriculture 1989-1991 Continuing Survey of Food Intakes by Individuals (1989-1991 CSFII). The Boron Nutrient Database (version 1.0) was then linked to the 3-day food records of 11,009 respondents to the 1989-1991 CSFII to generate the average daily boron intake for each person. The weighted 5th percentile, median, mean, and 95th percentile boron intakes, respectively, are 0.43, 1.02, 1.17 and 2.42 mg/day for men; 0.33, 0.83, 0.96 and 1.94 mg/day for women; and 0.40, 0.86, 1.01 and 2.18 mg/day for pregnant women. For vegetarian adults, these intakes are 0.46, 1.30, 1.47 and 2.74 mg/day for men and 0.33, 1.00, 1.29 and 4.18 mg/day for women. The top 2 boron contributors, coffee and milk, are low in boron, yet they make up 12% of the total boron intake by virtue of the volume consumed. Among the top 50 boron contributors, peanut butter, wine, raisins, peanuts, and other nuts are high in boron. As more data become available on daily boron requirements, the results of this study may be used to assess whether Americans' daily intake of boron is adequate.

Animals↗
PubMed1998

Vaginitis.

Explore the source record for details and available documents.

Animals↗
PubMed1998

In vivo percutaneous absorption of boric acid, borax, and disodium octaborate tetrahydrate in humans compared to in vitro absorption in human skin from infinite and finite doses.

Literature from the first half of this century report concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10%, in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percentage dose, with flux and permeability constant (Kp) calculated at 0.009 microgram/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percentage of dose, with flux and Kp calculated at 0.009 microgram/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percentage, with flux and Kp calculated at 0.01 microgram/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. In vitro human skin percentage of doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 micrograms/cm2/h and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05, 0.5, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microliters/cm2 volume. At 2 microliters/cm2 (the in vivo dosing volume), flux decreased some 200-fold to 0.07 microgram/cm2/h and Kp of 1.4 x 10(-6) cm/h, while percentage of dose absorbed was 1.75%. Borax dosed at 5.0%/1000 microliters/cm2 had 0.41% dose absorbed, flux at 8.5 micrograms/cm2/h, and Kp was 1.7 x 10(-4) cm/h. Disodium octaborate tetrahydrate (DOT) dosed at 10%/1000 microliters/cm2 was 0.19% dose absorbed, flux at 7.9 micrograms/cm2/h, and Kp was 0.8 x 10(-4) cm/h. These in vitro results from infinite doses (1000 microliters/cm2) were 1000-fold greater than those obtained in the companion in vivo study. The results from the finite (2 microliters/cm2) dosing were closer (10-fold difference) to the in vivo results. General application of infinite dose percutaneous absorption values for risk assessment is questioned by these results. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin, is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

Adult↗
PubMed1998

A comparison of worker exposure to inhalable and total dust, inorganic arsenic, and borates using two types of particulate sampling assemblies in a borate mining and processing facility.

This study describes a comparison of worker exposure to total and inhalable dust, inorganic As, and borates using two types of particulate sampling assemblies as part of a comprehensive industrial hygiene evaluation in a borate mining and processing facility. Employees were segmented into similar exposure groups (SEG) based on work location within the facility, job classification, and type of chemical agent. Approximately 10% of the employees from each SEG wore two personal sampling devices simultaneously for the purpose of collecting total and inhalable particulate fractions using a closed face, 37-mm mixed cellulose ester matched-weight filters (MMW), and Institute of Occupational Medicine (IOM) sampling assembly. Sample results indicated that the IOM concentrations were consistently higher than the corresponding MMW concentrations for all three agents. An analysis was performed to investigate a relationship between MMW and IOM. The data revealed correlation coefficient values of 0.72, 0.82, and 0.84 for total dust (n = 197), inorganic As (n = 137), and borates (n = 194), respectively. These positive correlation coefficients indicate that the IOM and MMW measurements are consistent with each other, and can be used for predicting exposure levels. The total dust and borate large mean ratios should be considered in developing inhalable fraction-based regulatory standards.

Air Pollutants, Occupational↗
PubMed1998

In vivo percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in humans: a summary.

Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry, which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10% in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percent dose, with flux and permeability constant (Kp) calculated at 0.009 microg/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percent dose, with flux and Kp calculated at 0.009 microg/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percent, with flux and Kp calculated at 0.01 microg/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

Administration, Topical↗
PubMed1998

In vitro percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in human skin: a summary.

Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax and disodium octaborate tetrahydrate (DOT) in biological matrices. In vitro human skin percent doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 microg/cm2/h, and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05%, 0.5%, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microL/cm2 volume. At 2 microL/cm2 (the in vivo dosing volume), flux decreased some 200-fold to 0.07 microg/cm2/h and Kp of 1.4 x 10(-6) cm/h, while percent dose absorbed was 1.75%. Borax dosed at 5.0%/1000 microL/cm2 had 0.41 percent dose absorbed, flux at 8.5 microg/cm2/h, and Kp was 1.7 x 10(-4) cm/h. Disodium octaborate tetrahydrate (DOT) dosed at 10%/1000 microL/cm2 was 0.19 percent dose absorbed, flux at 7.9 microg/cm2/h, and Kp was 0.8 x 10(-4) cm/h. These in vitro results from infinite doses (1000 microL/cm2) were a 1000-fold greater than those obtained in the companion in vivo study. The results from the finite (2 microL/cm2) dosing were closer (10-fold difference) to the in vivo results. General application of infinite dose percutaneous absorption values for risk assessment is questioned by these results.

Adult↗
PubMed1994

The relationship of blood- and urine-boron to boron exposure in borax-workers and usefulness of urine-boron as an exposure marker.

Daily dietary-boron intake and on-the-job inspired boron were compared with blood- and urine-boron concentrations in workers engaged in packaging and shipping borax. Fourteen workers handling borax at jobs of low, medium, and high dust exposures were sampled throughout full shifts for 5 consecutive days each. Airborne borax concentrations ranged from means of 3.3 mg/m3 to 18 mg/m3, measured gravimetrically. End-of-shift mean blood-boron concentrations ranged from 0.11 to 0.26 microgram/g; end-of-shift mean urine concentrations ranged from 3.16 to 10.72 micrograms/mg creatinine. Creatinine measures were used to adjust for differences in urine-specific gravity such that 1 ml of urine contains approximately 1 mg creatinine. There was no progressive increase in end-of-shift blood- or urine-boron concentrations across the days of the week. Urine testing done at the end of the work shift gave a somewhat better estimate of borate exposure than did blood testing, was sampled more easily, and was analytically less difficult to perform. Personal air samplers of two types were used: one, the 37-mm closed-face, two-piece cassette to estimate total dust and the other, the Institute of Occupational Medicine (IOM) sampler to estimate inspirable particulate mass. Under the conditions of this study, the IOM air sampler more nearly estimated human exposure as measured by blood- and urine-boron levels than did the sampler that measured total dust.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Incidence of lung cancer by histological type from a population-based registry.

Using data from a population-based registry, the Cancer Surveillance Program of Orange County, we examined patterns in lung cancer incidence by histological type for 1984 in Orange County, CA. Age-adjusted incidence rates per 100,000 population are 66.4 for men and 34.1 for women. Compared to 1983 rates for whites from all SEER areas combined, Orange County incidence rates are lower for men but equal for women. Squamous cell carcinoma incidence shows a strong male predominance [male/female 3.4; 95% confidence interval = (2.6, 4.4)], whereas the male/female incidence ratios for adenocarcinoma [male/female 1.4; 95% confidence interval = (1.1, 1.8)] and small cell carcinoma [male/female = 1.8; 95% confidence interval = 1.3, 2.4)] are closer to unity. Smoking habits were abstracted from medical records for 79% of cases. Only 8% of lung cancer cases (5% of men and 12% of women) with known smoking habits are nonsmokers. Adenocarcinoma is the most common cell type among women smokers and nonsmokers, while squamous cell carcinoma predominates in both male smokers and nonsmokers. Cases who smoked were younger at diagnosis than nonsmokers (P less than 0.001) for each cell type. Despite a greater proportion of nonsmokers, cases with adenocarcinoma were younger at diagnosis compared to small cell carcinoma (P less than 0.01) and squamous cell carcinoma (P less than 0.05). The observed patterns of incidence rates by histological type are not entirely explained by current knowledge of the relationship between smoking and cell type.

Adenoma↗
PubMed1988

Immune response in shipyard workers with x ray abnormalities consistent with asbestos exposure.

The association of cellular and humoral immune responses with asbestos exposure was studied in two groups of 150 workers each from a shipyard population and compared with a population of Red Cross blood donors. One of the shipyard groups had both chest x ray evidence of asbestos exposure and work assignments that necessitated direct handling of asbestos. The other shipyard group had normal chest x ray films and no job assignments involving the direct handling of asbestos. Cellular immune responses studied were mitogen activation and measures of T helper and T suppressor cells. Humoral immune measures were IgG, IgA, and IgM. In shipyard workers with asbestos related x ray abnormalities there was a significant increase in pokeweed mitogen stimulation. In both shipyard groups compared with Red Cross blood donors were found (1) significantly higher IgG and IgA levels and (2) greater numbers of T helper and T suppressor cells; because of the disproportionately large number of T suppressor cells, Th/Ts ratios were lower than in the Red Cross controls. Observations of differences in humoral and cellular immune response may point the way to the early diagnosis of the clinical manifestation of asbestos related disease.

Asbestos↗
PubMed1986

Anti-HTLV III ELISA and Western blot testing in a blood donor population: implications for donor notification.

We have evaluated the western blot (WB) test for distinguishing anti-HTLV III ELISA-positive donors who have likely been exposed to HTLV III from those that are false positives. Of 1,955 donors, 26 were positive for anti-HTLV III by ELISA testing. Only 6 (23%) were positive by WB: 5 of these 6 were male homosexuals with multiple partners and 5 of 6 had low Th/Ts ratios. The WB-positive donors gave the highest absorbance values in the anti-HTLV III ELISA assay. The immunologic abnormalities in the WB-positive donors suggest that they should be notified of their test results. We conclude that basing a donor notification policy on WB results is the optimum public health strategy for blood banks at the present time.

Antibodies, Viral↗
PubMed1985

A study of multiple biological markers in twins.

Genetic and environmental influences on the phenotypic expressions of several biological markers were studied in 18 monozygous (MZ) and 8 dizygous (DZ) twin pairs. Zygosity was determined using ABO, Rh, and HLA. The biomarkers studied included: T & B lymphocytes, suppressor and helper T lymphocytes (T gamma, T mu), T cell (PHA) mitogen activation (MA), serum immunoglobulins (IgA, IgM, and IgG), plasma carcinoembryonic antigen (CEA), aryl-hydrocarbon hydroxylase (AHH) and sister chromatid exchange (SCE) in lymphocytes. Temporal variation of markers over a 6-month period was not significant. The mean absolute differences between levels from first and second blood draws were less than one standard deviation. Variability associated with age was not significant. Females had higher levels of T lymphocytes than males. A gender related association was observed for the IgM immunoglobulin test: females had a higher mean level of IgM. Smoking was found to influence the levels of SCE, T helper lymphocytes and mitogen activation. The variability of these biomarkers within and between twin pairs was quantified. Immunoglobulin levels, particularly that of IgM, showed statistically greater similarity within MZ twins than within DZ twins. Several other markers suggested heritability.

Adult↗
PubMed1982

Subclinical effects of chronic increased lead absorption--a prospective study. Part IV. Evaluation of heme synthesis effects.

The effects of lead exposure on heme synthesis in workers with subclinical responses and in controls were evaluated. delta-Aminolevulinic acid dehydratase (ALA-d) correlated significantly with blood lead levels in the control group but not with those in the exposed group. Free erythrocyte protoporphyrin correlated significantly with blood lead levels in the exposed group but not with those in the controls and was found to be a good indicator of blood lead history among exposed persons. Hemoglobin values determined at initial employment were not statistically different from those determined during the baseline test for a group of 12 workers with a maximum blood lead level of 86 micrograms/100 ml during their exposure history. The effect such heme inhibition may have on other body functions is uncertain.

Environmental Exposure↗
PubMed1980

Pulmonary disease in workers exposed to papain: clinico-physiological and immunological studies.

Of the twenty-three employees at a pharmaceutical plant manufacturing a new product containing papain, twelve had respiratory symptoms of cough, wheezing, dyspnoea, or chest paint. Most were studied with in-depth interviews by a doctor, extensive pulmonary function tests, and immunoserological tests for IgE and precipitating antibodies specific for papain, as well as total IgE antibodies to common natural allergens. There were significant correlates (all P values < 0.05) between the presence of specific IgE antibodies to papain and decreases of FEV1, FEF75--85, TLC, RV, and response to bronchodilators as percentage change from baseline for all spirographic flow rates. Atopic workers developed pulmonary symptoms and antipapain antibodies significantly sooner after papain exposure than did the others. Duration of exposure had no effect on symptomatology, pulmonary function, or immunological response. However, those judged to have the greatest amount of dust exposure per work-day had significantly more pulmonary symptoms (P < 0.005). Papain produced lung diseases by acting as an inhalant allergen rather than a proteolytic enzyme. Papain is a potent sensitizer in humans for the production of respiratory disease. The pulmonary reactions, based on physiological data, seem to involve small airways, alveolar, and interstitial lung tissue in an inflammatory rather than destructive manner, and thus resemble bronchitis and interstitial lung disease rather than pulmonary emphysema or typical bronchial asthma.

Adult↗
PubMed1980

Subclinical effects of chronic increased lead absorption--a prospective study. III. Neurologic findings at follow-up examination.

Neurologic examination, nerve conduction testing and electro-oculographic testing have been performed at a baseline examination and a follow-up examination in a group of lead workers with blood lead levels predominantly between 60 and 80 micrograms/dl and in a group of control workers. A statistically significant decreased saccade accuracy measurement in the lead workers compared to the controls was found at both examinations. No other simple test or pattern of findings differentiated between the lead workers and the controls, and the biological significance of the lower saccade accuracy is not clear. Nerve conduction measurements do not appear to be a satisfactory method of detecting subclinical neurologic effects of lead exposure.

Humans↗
PubMed1979

Subclinical effects of chronic increased lead absorption--a prospective study. II. Results of baseline neurologic testing.

This report summarizes the results of baseline neurologic testing in a group of apparently healthy workers from a secondary lead smelter and a group of controls from nearby aluminum processing plants. The test battery included a standard neurologic examination nerve conduction measurements, quantitative oculomotor function tests and detailed audiologic studies. Lead workers and controls were intermixed so that the examiners were unaware of the status of any individual being tested. Although the lead workers reported significantly more neurologic symptoms than the controls, relatively few differences were found on quantitative neurologic testing. Decreased deep tendon reflexes occured more frequently in the lead workers than in the controls (22% vs. 11%) but the difference was of borderline significance (p=0.06) and other signs of peripheral neuropathy occurred with equal frequency in both groups. The mean motor conduction velocity and sensory latency measurements were not significantly different in the lead workers and in the controls and, of the six oculomotor function measurements, only the mean accuracy of saccadic eye movements was significantly (p less than 0.01) different in the two groups. High frequency hearing loss occurred with equal frequency and severity in both groups, consistent with the level of noise exposure in the lead and control plants.

Absorption↗
PubMed1979

Subclinical effects of chronic increased lead absorption--a prospective study. I. Study design and analysis of symptoms.

Seventy workers exposed to lead for at least one year and 35 control workers have been enrolled in a prospective study of possible neurologic effects of chronic lead absorption at or below the current standard of 80 microgram per 100 ml whole blood. The study design is described in detail. Initial results of analysis of lead-related symptoms from baseline studies indicate few differences between the exposed and nonexposed workers. The majority of differences were for central nervous system (CNS) symptoms and muscle or joint pain. Little correlation was found between symptom reporting and indices of lead absorption. The evidence suggests that factors other than lead absorption itself may be important in symptom reporting.

Absorption↗