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Health aspects, Physiological aspects, Research, Control, Hyperlipoproteinemia -- Health aspects, Cholesterol -- Physiological aspects, Low cholesterol diet -- Research, Blood cholesterol -- Control, and Low-cholesterol diet -- Research

Both cholesterol and saturated fat in the diet have been linked to increased risk of coronary artery disease. Dietary cholesterol and saturated fat appear to contribute to heart disease by raising blood cholesterol. The elevated circulating cholesterol may adhere to the inner walls of the coronary arteries, slowing or blocking blood flow. While dietary cholesterol is only found in animal foods such as meat, eggs and dairy products, saturated fat may be found in animal or vegetable foods. Persons who wish to reduce their risk of heart disease are usually advised to make several changes in their diet: reduce cholesterol, reduce saturated fat, and increase fiber. The 58 participants followed a low-saturated-fat, high-fiber diet throughout the 12 weeks. To this background diet were added nine eggs per week for the first four weeks, zero eggs for the second four weeks and nine eggs per week for the last four weeks. Eggs were used as a source of cholesterol. The participants' blood cholesterol levels did not change significantly when the number of eggs was changed from nine to zero and back to nine. The subjects showed no consistent evidence of 'hyperresponse', defined as a greater than average increase in blood cholesterol in response to a given increase in dietary cholesterol. It is concluded that once a person is eating a low-saturated-fat, high-fiber diet, reducing dietary cholesterol to below 400 mg per day provides little additional benefit in terms of lowering blood cholesterol. A cholesterol intake of 400 mg per day is considered moderate and was provided in the diet containing nine eggs per week. When subjects added zero eggs to the background diet they consumed 90 mg cholesterol per day.

This study tested the performance optimality hypothesis of action identification theory in the context of self-presentation. Optimal performance is said to occur when a personally easy action is identified in relatively high level terms (i.e., the action's goals and likely effects) or a personally difficult action is identified in relatively low level terms (i.e., the action's mechanical details). To test this idea with respect to self-presentation, subjects were asked to describe themselves to either a difficult-to-impress or an easy-to-impress stranger in advance of a get-acquainted conversation with him or her. Subjects were induced to think about the self-description task in either high level terms (e.g., demonstrating their personality) or low level terms (e.g., smiling when appropriate). Support for the optimality hypothesis was obtained in subjects' self-reports of their self-presentation effectiveness and in observers' evaluations of subjects. Discussion centered on the manifestation of self-presentation nonoptimality in the early stages of relationship formation.

Data from 12 US case-control studies of ovarian cancer, conducted during the period 1956–1986 and representing some 3, 000 cases and 10,000 controls, were pooled and reanalyzed. Separate analyses were conducted for four subgroups of the pooled data: invasive epithelial ovarian cancers in white women; epithelial ovarian cancers of low malignant potential in white women, epithelial ovarian cancers in black women, and nonepithelial ovarian cancers. This paper gives a brief description of the participating studies and describes the methods used in the collaborative analysis. Am J Epidemiol1992; 136: 1175–83

Data collected from 2,197 white ovarian cancer patients and 8,893 white controls in 12 US case-control studies conducted in the period 1956–1986 were used to evaluate the relation of invasive epithelial ovarian cancer to reproductive and menstrual characteristics, exogenous estrogen use, and prior pelvic surgeries. Clear trends of decreasing risk were evident with increasing number of pregnancies (regardless of outcome) and increasing duration of breast feeding and oral contraceptive use. Ovarian dysfunction leading to both infertility and malignancy is an unlikely explanation for these trends for several reasons: 1) The trends were evident even among the highly parous; 2) risk among nulliparous women did not vary by marital status or gravidity; and 3) risk among ever-married women showed little relation to length of longest pregnancy attempt or history of clinically diagnosed infertility. Risk was increased among women who had used fertility drugs and among women with long total duration of premenopausal sexual activity without birth control; these associations were particularly strong among the nulligravid. No consistent trends in risk were seen with age at menarche, age at menopause, or duration of estrogen replacement therapy. A history of tubal ligation or of hystereclomy with ovarian conservation was associated with reduced ovarian cancer risk. These observations suggest that pregnancy, breast feeding, and oral contraceptive use induce biological changes that protect against ovarian malignancy, that, at most, a small fraction of the excess ovarian cancer risk among nulliparous women is due to infertility, and that any increased risk associated with infertility may be due to the use of fertility drugs. Am J Epidemiol 1992; 136: 1184–1203

Epithelial ovarian neoplasms of low malignant potential, also called borderline ovarian tumors, have various features of malignancy, but they do not invade the ovarian stroma. Women with these tumors usually are younger when diagnosed and have better prognoses than do women with invasive tumors. There have been few epidemiologic studies of borderline tumors, and it is unclear whether there are etiologic differences between the two types of tumor behavior. Combined data from nine case-control studies, conducted from 1974 to 1986 and representing 327 white women with tumors of low malignant potential and 4, 144 white controls, were used to evaluate the relation between these tumors and personal characteristics related to invasive ovarian cancer. The risk profile for tumors of low malignant potential was found to be similar to that for invasive tumors, with two exceptions: Compared with that of invasive tumors, risk of borderline tumors was less clearly reduced among women who had used oral contraceptives and more clearly elevated among women with a history of Infertility. Am J Epidemiol 1992; 136: 1204–11

Two hypotheses have been proposed to explain the reduced risk of epithelial ovarian cancer associated with pregnancy and oral contraceptive use. The first states that some sequelae of ovulation increase the likelihood of malignancy and that pregnancies and oral contraceptives protect by suppressing ovulation. The second hypothesis states that circulating levels of pituitary gonadotropins increase the risk of malignancy and that pregnancies and oral contraceptives protect by suppressing secretion of these hormones. The authors evaluate the two hypotheses in light of combined data from 12 United States case-oxitrol studies of epithelial ovarian cancer in white women conducted from 1956 to 1986. While a number of observations support both hypotheses, there are exceptions. Differential risk reduction associated with pregnancy and oral contraceptive use (pregnancy being the more effective in young women and the less effective in older women) conflicts with the first “ovulation” hypothesis, while reduced risk associated with breast feeding and absence of altered risk associated with estrogen replacement therapy conflicts with the second “gonadotropin” hypothesis. Several findings would not have been predicted by either hypothesis, e.g., only weak trends relate cancer risk to age at menarche, and, among older women, no clear trends relate risk to age at menopause. Odds ratio attenuation due to errors in reporting personal characteristics may be responsible for some of these inconsistencies. Multidisciplinary research is needed to clarify the etkrfogic roles of ovulation and gonadotropin stimulation, both of which may enhance carcinogenesis in the ovarian epithelium. Am J Epidemiol 1992: 136: 1212–20

Background Previous epidemiologic studies of ovarian cancer have focused chiefly on White women, who have a higher incidence of ovarian cancer than Black women. No study has previously examined risk factors for ovarian cancer among Black women. Purpose This study was designed to evaluate the risk of epithelial ovarian cancer in Black women in relation to reproductive characteristics such as pregnancy, oral contraceptive use, and breast-feeding, and to determine whether differences in reproductive factors between Black and White women account for differences in ovarian cancer incidence. Methods Combining interview data from seven case-control studies, we compared reproductive characteristics of 110 Black case subjects with a diagnosis of epithelial ovarian cancer between 1971 and 1986 with characteristics of 251 Black population control subjects and 114 Black hospital control subjects. We also compared the prevalence of reproductive factors in 246 Black population control subjects and 4378 White population control subjects and estimated the fraction of Black-White differences in ovarian cancer incidence attributable to racial differences in prevalence of these characteristics. Results Decreased risks of epithelial ovarian cancer in Black women were associated with parity of four or higher (odds ratio [OR]=0.53; 95% confidence interval [CI]=0.25–1.1), breast-feeding for 6 months or longer (OR=0.85; 95% CI=0.36–2.0), and use of oral contraceptives for 6 years or longer (OR=0.62; 95% CI=0.24–1.6). A greater proportion of Black women (48%) than White women (27%) reported four or more term pregnancies, and Black women (62%) were more likely than White women (53%) to have breast-fed their children. Oral contraceptive use was more common among White women (59%) than Black women (51%). Conclusions Differences in the prevalence of other factors related to ovarian cancer risk or differences in genetic susceptibility must explain most of the Black-White differences in incidence of ovarian cancer. [J Natl Cancer Inst 85:142–147, 1993]

Physiological aspects, Development and progression, Cancer invasiveness -- Physiological aspects, and Laryngeal cancer -- Development and progression

Background. Anatomic barriers to the spread of laryngeal cancer include the conus elasticus, the quadrangular membrane, and the thyroid cartilage. It has been speculated that an elastic barrier surrounds and protects the ventricle. Methods. The authors studied the microanatomic patterns of spread of 17 cases of patients who had laryngeal cancer with paraglottic disease and confirmed their findings by examining normal autopsy specimens. Results. Five patients of the seventeen cases showed no ventricular mucosal involvement despite extensive paraglottic disease. Both an inner, central, subepithelial periventricular elastic barrier, and a more peripheral periventricular elastic membrane barrier were identified; the latter was in continuity with the conus elasticus and quadrangular membrane. Conclusions. Two weak fibroelastic barriers surround the ventricle. The outer, peripheral, fibroelastic membrane is contiguous with the conus elasticus and the quadrangular membrane. Therefore, ventricular involvement is not a sensitive indicator of paraglottic spread. Squamous cell cancer may grow around the periventricular barriers to involve both the true and false cords but may spare the ventricle. The prognostic significance of the violation or preservation of the periventricular elastic barriers is unknown.

Little is known about the biochemical changes underlying the morphological differentiation of the sea urchin egg during oogenesis. Because of this and the essential role of gamete recognition in fertilization, we studied the developmental expression of the recently identified egg surface receptor for sperm during oogenesis. Consecutive stages of ovaries undergoing oogenesis over a 4-month time course were examined morphologically and assessed with respect to content of sperm receptor mRNA, as well as the content and subcellular distribution of the sperm receptor glycoprotein. Although in early oocyte stages neither mRNA encoding for the receptor nor receptor glycoprotein was detectable, at the last two stages of development the level of receptor mRNA accumulation increased dramatically. This finding correlated well with immunoblot analyses which established that sperm receptor protein was only detectable at the last two stages of egg maturation. Interestingly, immunocytochemistry showed that the formation of the receptor correlated temporally and spatially with the formation of cortical granules. In the earlier of these two stages of maturation, the receptor population identified by immunoblotting was found by immunocytochemistry to be restricted to the cortical granules and small vesicles in the cytoplasm. In contrast, at the last stage of egg maturation, sperm receptor was also detected at the surface of the oocyte, localized predominantly to the microvilli. Two receptor populations appear to exist, one in cortical granules and a second at the cell surface that may be formed via secretory vesicles. The late appearance of the receptor on the plasma membrane during oogenesis is consistent with its biological role in binding sperm to the mature egg cell surface.