Biomedical subjects

D Bauman

Publications and source records attributed to D Bauman.

At least 19 recordsLinked to original sources

PubMed2001

Vaccenic acid feeding increases tissue levels of conjugated linoleic acid and suppresses development of premalignant lesions in rat mammary gland.

The objective of this report was to determine whether vaccenic acid (t11-18:1) is converted efficiently to conjugated linoleic acid (c9,t11-18:2, CLA) in rats via the delta 9-desaturase reaction and, if so, whether vaccenic acid could substitute for CLA as an anticancer agent. In Study 1, rats were fed 1%, 2%, or 3% vaccenic acid in their diet, and tissue levels of CLA and CLA metabolites were determined in liver and mammary gland. In general, concentrations of CLA and CLA metabolites increased proportionately with an increase in vaccenic acid intake, at least up to the 2% dose level. Beyond this dose, there was clearly a plateauing effect. Thus vaccenic acid concentration increased from an undetectable level in the control to 78.5 nmol/mg lipid in the liver of rats fed a 2% vaccenic acid diet. This was accompanied by an increase in CLA from 2.3 to 33.6 nmol/mg lipid. These changes were also mirrored in the mammary gland, where increases in vaccenic acid (from 27.5 to 163.2 nmol/mg lipid) and CLA (from 17.8 to 108.9 nmol/mg lipid) were similarly observed. Vaccenic acid at 2% produced a CLA concentration in the mammary gland that was historically associated with a positive response in tumor inhibition based on our past experience. This provided the basis for selecting 2% vaccenic acid in Study 2, which was designed to evaluate its efficacy in blocking the development of premalignant lesions in the rat mammary gland. In this experiment, formation of histologically identifiable pathology due to intraductal proliferation of terminal end bud cells of mammary epithelium was used as the end point of analysis at 6 wk after carcinogen administration. Treatment with vaccenic acid reduced the total number of these premalignant lesions by approximately 50%. We hypothesize that the anticancer response to vaccenic acid is likely to be mediated by its endogenous conversion to CLA via delta 9-desaturase.

8,11,14-Eicosatrienoic Acid↗

PubMed2000

Sexual harassment in dentistry: experiences of Virginia dental hygienists.

PURPOSE: The purpose of this study was to determine if dental hygienists in the Commonwealth of Virginia experienced sexual harassment while employed in oral health care settings. Other interests were to determine if dental hygienists experienced sexual harassment, to what extent they felt professionally prepared to respond to unwanted sexual behaviors; did they perceive sexual harassment as a problem in the oral health care environment; and was attrition from their employment associated with sexual harassment. METHODS: A questionnaire, Sexual Harassment in the Dental Hygiene Profession, designed by the author, was used in this research. A list of currently licensed and registered dental hygienists was obtained from the Virginia Board of Dental Examiners and the questionnaire was sent to 540 randomly selected registered Virginia dental hygienists. Two weeks after the initial mailing, a second questionnaire was sent to non-respondents. The survey elicited data on experience, management, and personal opinions relative to sexual harassment, as well as demographic information. Results were analyzed using frequencies, percentages, and the chi-square test of association. RESULTS: Two hundred eighty-five surveys (53%) were returned and useable. Findings revealed that 54% of the responding dental hygienists experienced sexual harassment. Of these, 50% experienced sexual harassment four or more years ago, 23% one to three years ago and 28% within the last year; these categories were mutually exclusive. The perpetrators of the harassment were reported to be either male dentists (73%) or male clients (45%). Less than 10% reported being harassed by women. While 70% of the sexually harassed respondents indicated that filing formal complaints was an effective strategy for managing sexual harassment, less than 1% actually did so. Of all dental hygienists (harassed or not), 90% did not receive training in their dental education to manage sexual harassment, and 85% would like the American Dental Hygienists' Association to develop model guidelines and policies. Demographic characteristics were typical of practicing dental hygienists in Virginia; 99% female, 96% Caucasian, and 86% married with a mean age of 40 years. CONCLUSION: Information about managing sexual harassment needs to be incorporated into the dental hygiene curricula. This curriculum addition should include information on identifying sexual harassment incidents, strategies for controlling unacceptable behavior, the legal rights of employees, and the process of filing a formal complaint. Dental hygienists need to identify sexual harassment behaviors and receive prevention training though continuing education courses. Furthermore, the American Dental Hygienists Association and the American Dental Association need to collaboratively develop guidelines and policies for dentists and dental hygienists regarding the management of sexual harassment in the oral health care setting.

Adult↗

PubMed1999

Conjugated linoleic acid-enriched butter fat alters mammary gland morphogenesis and reduces cancer risk in rats.

Conjugated linoleic acid (CLA) is a potent cancer preventive agent in animal models. To date, all of the in vivo work with CLA has been done with a commercial free fatty acid preparation containing a mixture of c9,t11-, t10,c12- and c11,t13-isomers, although CLA in food is predominantly (80-90%) the c9,t11-isomer present in triacylglycerols. The objective of this study was to determine whether a high CLA butter fat has biological activities similar to those of the mixture of free fatty acid CLA isomers. The following four different endpoints were evaluated in rat mammary gland: 1) digitized image analysis of epithelial mass in mammary whole mount; 2) terminal end bud (TEB) density; 3) proliferative activity of TEB cells as determined by proliferating cell nuclear antigen immunohistochemistry; and 4) mammary cancer prevention bioassay in the methylnitrosourea model. It should be noted that TEB cells are the target cells for mammary chemical carcinogenesis. Feeding butter fat CLA to rats during the time of pubescent mammary gland development reduced mammary epithelial mass by 22%, decreased the size of the TEB population by 30%, suppressed the proliferation of TEB cells by 30% and inhibited mammary tumor yield by 53% (P < 0.05). Furthermore, all of the above variables responded with the same magnitude of change to both butter fat CLA and the mixture of CLA isomers at the level of CLA (0.8%) present in the diet. Interestingly, there appeared to be some selectivity in the uptake or incorporation of c9,t11-CLA over t10,c12-CLA in the tissues of rats given the mixture of CLA isomers. Rats consuming the CLA-enriched butter fat also consistently accumulated more total CLA in the mammary gland and other tissues (four- to sixfold increases) compared with those consuming free fatty acid CLA (threefold increases) at the same dietary level of intake. We hypothesize that the availability of vaccenic acid (t11-18:1) in butter fat may serve as the precursor for the endogenous synthesis of CLA via the Delta9-desaturase reaction. Further studies will be conducted to investigate other attributes of this novel dairy product.

Animals↗

PubMed1991

Temporomandibular joint dysfunction syndrome: a close association with systemic joint laxity (the hypermobile joint syndrome)

Sixty-two patients admitted for elective reconstructive surgery of the temporomandibular joint (TMJ) and eight seen as outpatients with a chief complaint of TMJ dysfunction during the same time interval were evaluated for possible etiologic factors contributing to the disease. All hospitalized patients had severe, end-stage degenerative changes within the TMJ, whereas outpatients had less severe disease and did not require surgery. TMJ dysfunction in some patients was said to be a result of established causes including bruxism, malocclusion, and trauma. No patient in this series had evidence of a systemic inflammatory polyarthritis. Of the 70 patients, 38 (54%) met criteria, based on those of Carter and Wilkinson, as modified by Beighton et al., sufficient to warrant a diagnosis of the hypermobile joint syndrome. Five patients had classic Ehlers-Danlos syndrome and therefore were not patients with "benign hypermobility," and an additional two cases were described as "marfanoid" and as possible Ehlers-Danlos syndrome, respectively. Radiographs showed TMJ hyperextensibility in four hypermobile patients. Long-term surgical outcome was identical in the hypermobile and nonhypermobile groups. The incidence of hypermobility in this series is strikingly higher than the expected incidence in an otherwise population. Magnetic resonance images of the TMJs on separate groups of asymptomatic normal and hypermobile women identified excessive anterior movement in the hypermobile group, together with abnormal anterior disk position in some. We hypothesize that hypermobility within the TMJ may cause accelerated disk destruction and degenerative disease.

Adolescent↗

PubMed1987

Circular dichroism and magnetic circular dichroism spectra of chlorophylls a and b in nematic liquid crystals. II. Magnetic circular dichroism spectra.

Absorption and magnetic circular dichroism (MCD) spectra are reported for chlorophyll (Chl) a and Chl b dissolved in nematic liquid crystal solvents. The spectra were measured with the dye molecules oriented uniaxially along the direction of. the magnetic field and measuring light beam. It is significant that under such conditions the MCD spectra recorded in the wavelength region of the Q and Soret bands of the chlorophyll are essentially unchanged with respect to rotation of the sample cell around this axis, even though there is almost complete orientation of the chlorophyll molecules by the liquid crystals. The MCD spectra of Chl a and b in the nematic liquid crystal solvents used in this study are surprisingly similar to the spectra obtained under isotropic conditions. These results illustrate an important technique with which to examine the optical spectra of dyes oriented in liquid crystal matrices in which the anisotropic effects can be reduced the negligible proportions by the application of a strong magnetic field parallel to the direction of the measuring light beam. The first deconvolution calculations are reported that describe the deconvolution of pairs of absorption and MCD spectra, in the Q and B band regions, for both Chl a and b. The spectral analysis to obtain quantitative estimates of transition energies was accomplished by carrying out detailed deconvolution calculations in which the both the absorption and MCD spectral envelopes were fitted with the same number of components; each pair of components had the same hand centres and bandwidth values. This procedure resulted in an assignment of each of the main transitions in the absorption spectra of both Chl a and b. Chl a is clearly monomeric, with Qy, Qx, By and Bx located at 671, 582, 439 and 431 nm, respectively. Analysis of the spectral data for Chl b located Qy, By and Bx, at 662, 476 and 464 nm, respectively.

Journal Article↗

PubMed1986

Obesity, non-protein-bound estradiol levels, and distribution of estradiol in the sera of breast cancer patients.

This study attempted to determine the relationship of nutritional status, menopausal status, presence of breast cancer, stage of disease, and tumor estrogen receptor levels to percent non-protein-bound estradiol (%NPBE) and percent distribution of estradiol on sex hormone-binding globulin (SHBG) and albumin in breast cancer patients and control patients. Normal-weight controls had significantly lower %NPBE compared with overweight controls and normal-weight and overweight breast cancer patients. There was a significant shift in the percent distribution of estradiol from SHBG to albumin in breast cancer patients, independent of body weight. Elevated %NPBE and abnormal percent estradiol distribution on albumin persisted after mastectomy and were unrelated to menopausal status, presence and stage of disease, and tumor estrogen receptor levels. These results show that breast cancer patients have increased exposure to unbound circulating estradiol and an increased percentage of estradiol bound to albumin, which may influence the availability of estradiol, considering its low binding affinity to albumin. Because these abnormalities persist after mastectomy, the current results may be important in developing dietary intervention protocols that correct %NPBE and abnormal estradiol distribution on binding proteins.

Adult↗

PubMed1980

Dichroism and polarized fluorescence of chlorophyll a, chlorophyll c and bacteriochlorophyll a dissolved in liquid crystals.

Three photosynthetic pigments were studied: chlorophyll a, chlorophyll c and bacteriochlorcphyll a in nematic liquid crystal matrixes. The polarized absorption and fluorescence spectra as a function of the electric field have been measured. From the polarized components of the absorption A( parallel) and A( perpendicular) of the pigments in liquid crystals two reduced components A(x) and A(y) are calculated (x and y are the direction of the axis which is going through the second, fourth pyrrol rings, and the first, third rings, respectively). From these results the orientation of chlorophylls in liquid crystals and the configuration of the transition moments in the skeleton of the pigment molecules were determined.

Journal Article↗

PubMed1980