Biomedical subjects
S Yen
Publications and source records attributed to S Yen.
Inelastic proton scattering at 200 to 400 MeV for 24Mg and 28Si in a microscopic framework.
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Gamow-Teller strength deduced from 54Fe(n,p) 54Mn cross sections at 298 MeV.
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Extrahepatic bile duct cancer and smoking, beverage consumption, past medical history, and oral-contraceptive use.
Information on potential causal factors in 67 patients with histologically confirmed cancer of the extrahepatic bile ducts was compared with that from 273 patients with other cancers. The control group did not include subjects with tobacco- or alcohol-related cancers. The study subjects were interviewed at 11 large hospitals in eastern Massachusetts and Rhode Island between 1975 and 1979. Among the patients with extrahepatic bile duct cancer, the male-female ratio was 1.5. The use of cigarettes was associated with decreased risk of extrahepatic bile duct cancer. The use of alcohol and coffee was not related to risk of extrahepatic bile duct cancer. Fewer patients than controls reported tea consumption. A statistically significant association between the use of oral contraceptives and extrahepatic bile duct cancer was observed among women under 60 years of age. Patients reported significantly higher frequencies of history of ulcerative colitis or diseases of the gallbladder.
Luteal contraception.
The impact of oral administration of RU 486 on the ongoing functional activity of the hypothalamic-gonadotropin-corpus luteum-endometrial (H-P-CL-E) axis was assessed during the mid-luteal (MLP) and the late-luteal phase (LLP) with and without hCG-induced pseudopregnancy. Longitudinal studies with daily dosing and frequent blood sampling were conducted during three consecutive cycles (control/treatment/recovery). During MLP, uterine bleeding occurred in all subjects within 36-72 h of the first dose of RU 486, but no histological changes were discernible on endometrial biopsy taken 12-24 h before bleeding. There was a significant decrease in LH secretion, pulse amplitude but not frequency. Response to GnRH on the last day of treatment was impaired. This was followed 3 days later by a rebound LH secretion lasting for 5 days. These events were accompanied by an initial decline of estradiol, but not progesterone, and a second peak of 5 days' duration for both estradiol and progesterone. Hence corpus luteum function was prolonged by 5 days, and second bleeding ensued following the spontaneous luteolysis. Recovery cycles were normal. During LLP, a single dose of RU 486 induced uterine bleeding in all cases. This was associated with a decreased LH pulse amplitude and frequency, and a faster decline of both estradiol and progesterone as compared to control cycles. Rescue of corpus luteum function by the administration of incremental doses of hCG failed to prevent the uterine bleeding after a single dose of RU 486. Recovery cycles were normal. While the antiprogesterone effect of RU 486 at the endometrial level was predictably expressed, its effects at the H-P-CL-E axis were also demonstrated. These findings provide important clues for the design of once-monthly contraceptive methods.
The influence of albumin on adsorption of bacteria on hydroxyapatite beads in vitro and human tooth surfaces in vivo.
Fewer streptococci adsorbed in vitro to hydroxyapatite (HA) beads treated with bovine albumin when compared to HA treated with buffer or with saliva. Approximately 60 per cent of adsorbed [3H]-albumin persisted on HA when incubated for 24 h in clarified whole or parotid saliva. Also, fewer bacteria were recovered from vigorously-pumiced, molar-tooth surfaces 24 h after application of albumin compared to buffer-treated controls.
Elastic and inelastic scattering of 362 MeV polarized protons from 40Ca.
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Energy dependence of the 12C(p, pi +)13C
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Coffee and pancreatic cancer (Chapter 2)
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The effect of westernization on urine estrogens, frequency of ovulation, and breast cancer risk. A study of ethnic Chinese women in the Orient and the USA.
In a 10-year incidence survey of breast cancer in the City of Boston, 14 cases in American Chinese women were observed, while approximately 13 were expected on the basis of age-specific incidence in the white population. In Hawaii, on the other hand, while breast cancer incidence rates for ethnic Chinese are approximately three times as high as those of indigenous Chinese populations, data indicate that they are still 35% lower than those of whites in Hawaii or on the US mainland. We have compared estrogen concentrations in the urine of Chinese women in the Orient, Honolulu, and Boston. Levels of estrone (E1) and estradiol (E2) increased greatly from the low to the high risk group. The increase was evident among both the younger (15-19 years) and the older (20-24 years) women, in both follicular and luteal phase specimens. The crude unweighted average increase from Oriental to continental US Chinese was about 38% and 34% for E1 and E2, respectively. On the other hand, levels of E3 decreased from the low-risk to the high-risk group, but the decrease was modest (16%) and not always regular. There were no systematic or significant differences in the frequency of ovulation in the three groups of women. These results are compatible with the hypothesis that high levels of estrone and estradiol are important to breast carcinogenesis. Whether E3 has some additional "protective" effect or is irrelevant is unclear. The data do not support the hypothesis that total urine estrogens (E1 + E2 + E3) are predictive of population groups at high risk for breast cancer and they appear inconsistent with the hypothesis that frequency of ovulation (or anovulation) is an important aspect of breast carcinogenesis.
Urine estrogens, frequency of ovulation, and breast cancer risk: case-control study in premenopausal women.
Urine specimens from 94 premenopausal women with breast cancer and from 70 control women have been compared with respect to concentration of the three major estrogen fractions and to frequency of ovulation as assessed by urine pregnanediol. The probability of anovulation (0.14 in the breast cancer patients and 0.09 among the controls) was not significantly higher among the women with breast cancer (P approximately 0.30). However, there was a positive association between urine estrogen concentration and breast cancer risk. The association was statistically significant (P less than 0.05) for each of the three estrogens measured and in both the follicular and the luteal phases of the menstrual cycle; the relative risk increased from 1 in the referent category (less than 5 micrograms estrogen/g creatinine) to about 3 in the highest category (greater than or equal to 15 micrograms estrogen/g creatinine). The association between urine estrogens and breast cancer risk was consistently stronger when the comparison was restricted to specimens collected in menstrual cycles during which ovulation occurred.
Consumption of alcohol and tobacco and other risk factors for pancreatitis.
Histories of alcohol and tobacco consumption and other potential risk factors were obtained from 98 patients with pancreatitis and 451 comparison patients at 11 large hospitals in Eastern Massachusetts and Rhode Island between 1975 and 1979. The great majority of the patients with pancreatitis had chronic or recurrent disease. From the comparison patients were excluded patients with other diseases of the pancreas and biliary tract and those admitted for disorders known to be associated with smoking or alcohol use. A statistically significant association of pancreatitis with alcohol use was present in males, but not in females. Cigarette use was very strongly associated with pancreatitis in males and less so in females. The associations with alcohol and cigarette use were independent, each retaining significance after adjustment for the other. There was no significant association of risk with coffee consumption in either sex. A history of biliary tract disease was given by 45 per cent of the male and 60 per cent of the female cases. The associations with alcohol use and cigarette smoking did not appear to be restricted either to the patients with or those without a history of biliary tract disease. Chronic or recurrent pancreatitis appears to have different dominant etiologies in males and females.
Coffee and cancer of the pancreas.
We questioned 369 patients with histologically proved cancer of the pancreas and 644 control patients about their use of tobacco, alcohol, tea, and coffee. There was a weak positive association between pancreatic cancer and cigarette smoking, but we found no association with use of cigars, pipe tobacco, alcoholic beverages, or tea. A strong association between coffee consumption and pancreatic cancer was evident in both sexes. The association was not affected by controlling for cigarette use. For the sexes combined, there was a significant dose-response relation (P approximately 0.001); after adjustment for cigarette smoking, the relative risk associated with drinking up to two cups of coffee per day was 1.8 (95% confidence limits, 1.0 to 3.0), and that with three or more cups per day was 2.7 (1.6 to 4.7). This association should be evaluated with other data; if it reflects a causal relation between coffee drinking and pancreatic cancer, coffee use might account for a substantial proportion of the cases of this disease in the United States.
Interaction specificities of a platinum metallointercalation reagent to DNA.
The interaction specificity of salmon sperm DNA with 2-hydroxyethanethionlato(2,2',2''-terpyridine)platinum(II),PtTS has been studied. The results of 1H and 13C nuclear magnetic resonance, flow dichroism and circular dichroism studies are found to be consistent with an intercalation mode of binding as has been proposed earlier by lippard and coworkers.
Estrogen profiles of premenopausal women with breast cancer.
Population surveys have demonstrated an inverse relationship between breast cancer incidence rates and the urine "estriol ratio," the concentration of estriol relative to the sum of the concentrations of estrone and estradiol. In this study, the urine estriol ratio was evaluated in premenopausal breast cancer patients and control women from Boston and San Francisco. Although at least 2 years had passed since last use of oral contraceptives, women with a history or oral contraceptive use for 19 months or longer excreted estrogen in low concentrations compared to nonusers and so were excluded. Among the remaining 73 cases and 55 controls, the cases had lower estriol ratios and higher estrone and estradiol levels than did controls. However, these differences, which averaged about 10%, were not statistically significant. Thus the hypothesis that a low estriol ratio is a cause of breast cancer is given only minimal support. Among women in their 40's, the excretion of estrogens is subject to many influences and is difficult to study. The many determinants of estrogen excretion, including age and oral contraceptive use, should be accommodated in the design of future studies of the estriol ratio.
Production of factors with immunosuppressive activity by a murine lymphoblastoid tumor cell line.
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Chronic mastitis and carcinoma of the breast.
733 women in whom chronic mastitis had been diagnosed were followed for an average of 30-3 years. 49 died from breast cancer compared with an expected number of 18-8. The excess risk of dying from breast cancer persisted for at least 30 years after chronic mastitis was diagnosed.