0044 Association Between Chronotype and Circulating Levels of Interleukin-6 in Colorectal Cancer Patients: Preliminary Results from the ColoCare Study

Introduction

Accumulating evidence suggests that chronotype, i.e., circadian topology of an individual indicating morning or evening type, is associated with inflammation. To date, no study has examined the relationship between chronotype and inflammation in colorectal cancer patients. We investigated the associations between chronotype and inflammatory and angiogenesis biomarkers in colorectal cancer patients.

Methods

We used pre-surgery serum samples from n=67 newly diagnosed colorectal cancer patients (stage I-IV) recruited at the ColoCare Study site in Heidelberg, Germany. The ColoCare Study is an ongoing, international, multisite, prospective cohort study in colorectal cancer patients. Inflammatory and angiogenesis biomarkers [c-reactive protein (CRP), interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1)] were measured at the Huntsman Cancer Institute, USA using the Meso Scale Discovery platform and were log transformed. Chronotype was assessed prior to surgery with the reduced Morningness-Eveningness Questionnaire (rMEQ; scale 4–25; a higher score indicates more morning-type). Patients were dichotomized, based on the median values for rMEQ, into 2 groups: rMEQ-low (score≤16.0; n=35; indicating more evening-type) or rMEQ-high (score>16.0; n=32; indicating more morning-type).

Results

Using Mann-Whitney U test, we observed that rMEQ-low group (i.e., more evening-type) compared to rMEQ-high group (i.e., more morning-type) had approx. two times significantly higher levels of log transformed IL-6 (mean=2.24 vs. 1.30; U=382.0; Z=-2.23; p=0.03), but not for other inflammatory or angiogenesis biomarkers. This association between chronotype and IL-6 was maintained even after adjusting for age, sex, tumor stage, tumor site, and sleep duration using a generalized estimating equations model (adjusted mean difference=1.10; 95% confidence interval=0.33, 1.88; p=0.01; effect size, Cohen’s d=0.69).

Conclusion

These preliminary findings suggest that the evening chronotype is associated with increased IL-6 inflammatory biomarker in colorectal cancer patients. Further research is needed to confirm and understand the mechanistic underpinnings of the observed results.

Support

Funding: NCI U01 CA206110, R01 CA189184, and R01 CA207371.

Evaluating environmental performance using new process capability indices for autocorrelated data

Traditionally, the process capability index is developed by assuming that the process output data are independent and follow normal distribution. However, in most environmental cases, the process data are autocorrelated. The autocorrelated process, if unrecognized as an independent process, can lead to erroneous decision making and unnecessary quality loss. In this paper, three new capability indices with unbiased estimators are proposed to relieve the independence assumption for the-nominal-the-best and the-smaller-the-better cases. Furthermore, we use mean squared error (MSE) and mean absolute percent error (MAPE) to compare the accuracy of our proposed indices to previous autocorrelated indices. The results show that our proposed capability indices outperform the predecessors.

Relationship between interpregnancy interval and birth defects in Washington State

OBJECTIVE

Interpregnancy interval (IPI) influences numerous adverse perinatal outcomes. IPI's impact on birth defects is unclear.

STUDY DESIGN

We conducted a population-based case-control study, using 1998 to 2008 administrative data from Washington State. A total of 10, 772 cases, women whose second of two births resulted in an infant with a birth defect, were compared with 32 ,310 controls, women whose second of two births did not result in an infant with a birth defect.

RESULT

Compared with mothers with an IPI between 18 to 23 months, those with an IPI <6 months or ≥60 months had elevated risks of delivering an infant with a birth defect (odds ratio=1.15, 95% confidence interval: 1.03 to 1.28, and odds ratio=1.15, 95% confidence interval: 1.04 to 1.26, respectively).

CONCLUSION

We observed a J-shaped relationship between IPI and risk of having an infant with a birth defect. As this is one of the first studies to evaluate this association, confirmatory studies are needed.

Gene expression array testing of FFPE archival breast tumor samples: an optimized protocol for WG-DASL sample preparation

Archived formalin-fixed, paraffin embedded (FFPE) tissues constitute a vast, well-annotated, but underexploited resource for the molecular study of cancer progression, largely because degradation, chemical modification, and cross-linking, render FFPE RNA a suboptimal substrate for conventional analytical methods. We report here a modified protocol for RNA extraction from FFPE tissues which maximized the success rate (with 100% of samples) in the expression profiling of a set of 60 breast cancer samples on the WG-DASL platform; yielding data of sufficient quality such that in hierarchical clustering (a) 12/12 (100%) replicates correctly identified their respective counterparts, with a high self-correlation (r = 0.979), and (b) the overall sample set grouped with high specificity into ER+ (38/40; 95%) and ER- (18/20; 90%) subtypes. These results indicate that a large fraction of decade-old FFPE samples, of diverse institutional origins and processing histories, can yield RNA suitable for gene expression profiling experiments.

Differential patterns of allelic loss in estrogen receptor-positive infiltrating lobular and ductal breast cancer

The two main histological types of infiltrating breast cancer, lobular (ILC) and the more common ductal (IDC) carcinoma are morphologically and clinically distinct. To assess the molecular alterations associated with these breast cancer subtypes, we conducted a whole-genome study of 166 archival estrogen receptor (ER)-positive tumors (89 IDC and 77 ILC) using the Affymetrix GeneChip(R) Mapping 10K Array to identify sites of loss of heterozygosity (LOH) that either distinguished, or were shared by, the two phenotypes. We found single nucleotide polymorphisms (SNPs) of high-frequency LOH (>50%) common to both ILC and IDC tumors predominately in 11q, 16q, and 17p. Overall, IDC had a slightly higher frequency of LOH events across the genome than ILC (fractional allelic loss = 0.186 and 0.156). By comparing the average frequency of LOH by chromosomal arm, we found IDC tumors with significantly (P < 0.05) higher frequency of LOH on 3p, 5q, 8p, 9p, 20p, and 20q than ILC tumors. We identified additional chromosomal arms differentiating the subtypes when tumors were stratified by tumor size, mitotic rate, or DNA content. Of 5,754 informative SNPs (>25% informativity), we identified 78 and 466 individual SNPs with a higher frequency of LOH (P < 0.05) in ILC and IDC tumors, respectively. Hierarchical clustering of these 544 SNPs grouped tumors into four major groups based on their patterns of LOH and retention of heterozygosity. LOH in chromosomal arms 8p and 5q was common in higher grade IDC tumors, whereas ILC and low-grade IDC grouped together by virtue of LOH in 16q.

Clinical characteristics of different histologic types of breast cancer

Breast cancer is a heterogeneous disease, though little is known about some of its rarer forms, including certain histologic types. Using Surveillance, Epidemiology, and End Results Program data on 135 157 invasive breast cancer cases diagnosed from 1992 to 2001, relationships between nine histologic types of breast cancer and various tumour characteristics were assessed. Among women aged 50–89 years at diagnosis, lobular and ductal/lobular carcinoma cases were more likely to be diagnosed with stage III/IV, ⩾5.0 cm, and node-positive tumours compared to ductal carcinoma cases. Mucinous, comedo, tubular, and medullary carcinomas were less likely to present at an advanced stage. Lobular, ductal/lobular, mucinous, tubular, and papillary carcinomas were less likely, and comedo, medullary, and inflammatory carcinomas were more likely to be oestrogen receptor (ER) negative/progesterone receptor (PR) negative and high grade (notably, 68.2% of medullary carcinomas were ER−/PR− vs 19.3% of ductal carcinomas). In general, similar differences were observed among women diagnosed at age 30–49 years. Inflammatory carcinomas are associated with more aggressive tumour phenotypes, and mucinous, tubular, and papillary tumours are associated with less aggressive phenotypes. The histologic types of breast cancer studied here differ greatly in their clinical presentations, and the differences in their hormone receptor profiles and grades point to their likely different aetiologies.

Epidemiologic and molecular risk factors for contralateral breast cancer among young women

Women diagnosed with a first breast cancer before the age of 45 years have a greater than 5.0-fold risk of developing a second primary contralateral breast cancer (CBC) than women in the general population have of developing a first breast cancer. Identifying epidemiologic or molecular factors that influence CBC risk could aid in the development of new strategies for the management of these patients. A total of 1285 participants in two case-control studies conducted in Seattle, Washington, who were 21-44 years of age when diagnosed with a first invasive breast carcinoma from 1983 to 1992, were followed through December 2001. Of them, 77 were diagnosed with CBC and 907 tumour tissues from first cancers were analysed. Women with body mass indices (BMIs) >/=30 kg m(-2) had a 2.6-fold greater risk (95% CI: 1.1-5.9) of CBC compared to women with BMIs </=19.9 kg m(-2). Women whose first tumour was c-erbB-2 positive had a 1.7-fold (95% CI: 1.0-3.0) excess CBC risk. Body mass index and c-erbB-2 expression may be risk factors for CBC in young women. Further observational studies are needed to confirm these findings and to evaluate whether testing for c-erbB-2 in this population may help identify those at high risk for CBC.

Approaching healthy body mass index norms for children and adolescents from health-related physical fitness

Current body mass index (BMI) norms for children and adolescents are developed from a reference population that includes obese and slim subjects. The validity of these norms is influenced by the observed secular increase in body weight and BMI. We hypothesized that the performance of children in health-related physical fitness tests would be negatively related to increased BMIs, and therefore fitness tests might be used as criteria for developing a more appropriate set of BMI norms. We evaluated the existing data from a nation-wide fitness survey for students in Taiwan (444 652 boys and 433 555 girls) to examine the relationship between BMI and fitness tests. The fitness tests used included: an 800/1600-m run/walk; a standing long jump; bent-leg curl-ups; and a sit-and-reach test. The BMI percentiles developed from the subgroup whose test scores were better than the 'poor' quartile in all four tests were compared with those of the whole population and linked to the adult criteria for overweight and obesity. The BMIs were significantly related to the results of fitness testing. A total of 43% of students had scores better than the poorest quartile in all of their tests. The upper BMI percentile curves of this fitter subgroup were lower than those of the total population. The 85th and 95th BMI percentile values of the fitter 18-year-old-students (23.7 and 25.5 kg m(-2) for boys; 22.6 and 24.6 kg m(-2) for girls) linked well with the adult cut-off points of 23 and 25 kg m(-2), which have been recommended as the Asian criteria for adult overweight and obesity. Hence, the BMI norms for children and adolescents could be created from selected subgroups that have better physical fitness. We expect that the new norms based on this approach will be used not only to assess the current status of obesity or overweight, but also to encourage activity and exercise.

Cue and context conditioning of defensive behaviors to cat odor stimuli

Exposure of rats to a cat odor block in a previously familiarized situation was followed by three extinction days to the same or a different situation, and with or without an identical but odor-free block, and, testing in the original apparatus with an odor-free block (cue). Initial exposure produced risk assessment (stretch attend), avoidance of the block, and crouch/freeze with sniffing/head movements. Avoidance continued during extinction, but context-only exposed rats showed predominantly crouch/freeze with sniff/head movements, while rats exposed to the context+cue showed higher levels of stretch attend. During the test day, rats exposed to the cue during extinction showed reduced defensive responding compared to those not extinguished with the cue, but context extinction had less effect, possibly due in part to initial familiarization with the situation. These data indicate that both cue and context conditioning to cat odor did occur, and that the type of conditioned stimulus (context-only vs. context+cue) influenced the type of defensive behaviors elicited by this stimulus, although the all animals received the same conditioning protocol. Particular behaviors disappeared at different rates during extinction, with avoidance the most persistent. However, in this context there was no incentive for approach behaviors inconsistent with avoidance, and stretch attend behaviors could and did occur while subjects were located far from the block or the area in which it had been encountered. In addition, immobile crouch/freeze did not occur at higher than control levels, while the crouch/freeze activities that did increase incorporated sensory sampling in a relevant modality (sniffing/head movements). Thus, the behaviors seen to the conditioned stimulus appeared to reflect combinations of different defense strategies, appropriate to the type of conditioned stimulus and responsive to its extinction. Differences between these data and those from studies using fecal predator odorants suggest that the latter may not elicit a complete range of conditioned defenses.

Tamoxifen therapy for primary breast cancer and risk of contralateral breast cancer

BACKGROUND

Women diagnosed with breast cancer have a twofold to sixfold greater risk of developing contralateral breast cancer than women in the general population have of developing a first breast cancer. Tamoxifen therapy reduces this risk, but it is unclear if this benefit exists for both estrogen receptor (ER)-positive and ER-negative contralateral tumors.

METHODS

Using data from a population-based tumor registry that collects information on the ER status of breast tumors, we followed 8981 women residing in western Washington State who were diagnosed with a primary unilateral invasive breast cancer during the period from 1990 through 1998 to identify cases of contralateral breast cancer. We restricted our analyses to women who were at least 50 years old and whose first breast cancer had a localized or regional stage; women who received adjuvant hormonal therapy but not chemotherapy (n = 4654) were classified as tamoxifen users, while those who received neither adjuvant hormonal therapy nor chemotherapy (n = 4327) were classified as nonusers of tamoxifen. By reviewing selected patient abstracts, we estimated that 94% of the subjects were classified correctly with respect to tamoxifen use. The risk of contralateral breast cancer associated with tamoxifen use was estimated with the use of Cox regression. All statistical tests were two-sided.

RESULTS

Of the 89 tamoxifen users and 100 nonusers of tamoxifen diagnosed with contralateral breast cancer, 112 had ER-positive tumors, 20 had ER-negative tumors, and 57 had tumors with an ER status that was unknown or had not been determined by an immunohistochemical assay. The risk of developing an ER-positive and an ER-negative contralateral tumor among tamoxifen users was 0.8 (95% confidence interval [CI] = 0.5 to 1.1) and 4.9 (95% CI = 1.4 to 17.4), respectively, times that of nonusers of tamoxifen. This difference in risk by ER status was statistically significant (P<.0001).

CONCLUSIONS

Tamoxifen use appears to decrease the risk of ER-positive contralateral breast tumors, but it appears to increase the risk of ER-negative contralateral tumors.

Multiple primary breast and thyroid cancers: role of age at diagnosis and cancer treatments (United States)

BACKGROUND

Breast and thyroid cancer have been observed to occur more frequently than expected as multiple primary tumors in women. The study presented herein focuses on the effects of age at diagnosis and treatment for the first cancer on the development of the second cancer.

METHODS

This retrospective cohort study used a study population consisting of 38,632 women diagnosed with primary invasive breast cancer and 2189 women diagnosed with primary invasive thyroid cancer between 1974 and 1994. Cases were identified from records of the Cancer Surveillance System of western Washington and followed for subsequent cancer development through 1995.

RESULTS

Seventy-one women were diagnosed during their lives with both breast and thyroid cancers. Including cancers diagnosed during the same month as or after the initial cancer, the relative risk (RR) of breast cancer among women with thyroid cancer was 1.5 (95% confidence interval [CI] 1.1-2.0), and the RR of thyroid cancer among women with breast cancer was 1.5 (95% CI 1.1-2.2). Among women with thyroid cancer, risk of breast cancer was greatest when the latter cancer was diagnosed under 45 years of age (RR = 2.3, 95% CI 1.1-4.4). First course of treatment, including radiation or hormonal therapy to treat thyroid cancer, and radiation, chemotherapy, or hormonal therapy to treat breast cancer, did not alter a woman's risk of developing the second cancer.

CONCLUSIONS

The data suggest that the incidence of breast and thyroid cancer may be related, and that in particular women with thyroid cancer may be at a moderately increased risk of developing breast cancer before age 45.

Changing incidence rate of invasive lobular breast carcinoma among older women

BACKGROUND

In 1998, an unusually large number of invasive lobular breast carcinoma cases were seen at the University of Washington. The purpose of this study was to assess whether the incidence rate of invasive lobular carcinoma has been increasing disproportionately compared with the incidence rate of invasive ductal carcinoma.

METHODS

Age specific and age-adjusted breast carcinoma incidence rates from 1977-1995 were obtained from the nine population-based cancer registries that participate in the Surveillance, Epidemiology, and End Results (SEER) program. Three histologic groupings were used: lobular, ductal, and all invasive breast carcinomas. Overall incidence rates for each grouping, as well as for each stage (local, regional, and distant), were obtained.

RESULTS

The rate of incidence of lobular carcinoma increased steadily from 1977-1995 in women age >/= 50 years whereas it remained stable in women age < 50 years. Alternatively, the rate of incidence of ductal carcinoma increased steadily from 1977-1987, but from 1987-1995 it remained relatively constant across all age groups.

CONCLUSIONS

The incidence rates of invasive lobular breast carcinomas increased steadily since 1977 whereas the incidence rates of invasive ductal carcinoma have plateaued since 1987. This rise occurred specifically among women age >/= 50 years and may be related to postmenopausal status. Further epidemiologic, clinical, and laboratory research is required to assess what factors are contributing to this trend.

Hormone replacement therapy in relation to risk of lobular and ductal breast carcinoma in middle-aged women

BACKGROUND

In the majority of studies, long term, recent use of hormone replacement therapy has been associated with an increased risk of breast carcinoma. However, little attention has been paid to the possibility that the magnitude of this association may vary according to the histologic type of breast carcinoma.

METHODS

In this population-based case-control study, interviews were conducted with 537 female residents of King County, Washington who were ages 50-64 years and who had been diagnosed with primary breast carcinoma between January 1, 1988 and June 30, 1990. Interviews with 492 randomly selected King County women without a history of breast carcinoma served as a basis for comparison. Analyses were performed separately for women with lobular and for those with ductal tumors.

RESULTS

Compared with nonusers of menopausal hormones, those who currently were using combined estrogen and progestin hormone replacement therapy (CHRT) and had done so for at least 6 months had an elevated risk of lobular breast carcinoma (odds ratio [OR] = 2.6; 95% confidence interval [95% CI], 1.1-5.8), but no change in their risk of ductal breast carcinoma was noted (OR = 0.7; 95% CI, 0.5-1. 1). The OR associated with current use of unopposed estrogen for at least 6 months was 1.5 (95% CI, 0.5-3.9) for lobular tumors and 0.7 (95% CI, 0.4-1.1) for ductal tumors. Similar results were found when cases of invasive tumor were analyzed separately.

CONCLUSIONS

The results of this study suggest that CHRT use increases the risk of lobular, but not ductal, breast carcinoma in middle-aged women.

Anthropometric variables in relation to risk of breast cancer in middle-aged women

BACKGROUND

Many epidemiological studies have assessed the relationships between anthropometric variables and breast cancer risk. However, methodological approaches for analysing these factors differ appreciably. Also, age when maximum height is achieved has been identified as a potential risk factor for breast cancer in premenopausal women, but this issue has not been studied in postmenopausal women.

METHODS

The participants in this population-based case-control study were postmenopausal women 50-64 years of age from the general female population of western Washington State. It included 479 women with incident primary breast cancer and 435 controls.

RESULTS

This study found that: (i) women who gained over 70 pounds since age 18 had an increased risk of breast cancer relative to those who stayed within 10 pounds of their weight at age 18 (odds ratio [OR] = 2.7; 95% CI: 1.5-4.9), (ii) women with body mass indices (BMI) below what is considered healthy had a decreased risk (OR = 0.4; 95% CI: 0.2-1.1) while women with a BMI in the obese range had an increased risk of breast cancer (OR = 1.4; 95% CI: 1.0-2.1), and (iii) women who reached their maximum height at or after the age of 18 had a decreased risk of breast cancer compared to women who reached their maximum height at age 13 or younger (OR = 0.7; 95% CI: 0.5-1.0).

CONCLUSIONS

By examining various anthropometric variables using clinically relevant strata, a clearer picture of how these variables relate to postmenopausal breast cancer risk was developed. Similar to younger women, postmenopausal women who reached their maximum height at later ages had a decreased risk of breast cancer.

Association between serum uric acid and cardiovascular risk factors among elderly people in Taiwan

In order to understand the distribution of serum uric acid and the relationship between serum uric acid and the cardiovascular risk factor among elderly people, a cross-sectional study was conducted in Chung-Shing-Shin-Tseun community in Taiwan in May 1998. All individuals aged 65 and over were collected. A total of 1123 persons, out of 1774 registered residents, were contacted by face-to-face interview. The response rate was 63.3%. However, only 586 respondents had blood tests and completed questionnaires. Analysis in this study was based on these 586 subjects. The mean uric acid values were 7.4 +/- 1.8 mg/dl in men and 6.3 +/- 1.6 mg/dl in women, respectively (p < 0.001). Multivariate linear regression showed that serum uric acid was significantly correlated with sex and body mass index. Simple correlation showed that serum uric acid was significantly correlated with diastolic pressure, total cholesterol, triglyceride and creatinine. Age, systolic pressure and fasting glucose were not related to serum uric acid. In our conclusion, the uric acid values are high among elderly people. The serum uric acid levels are significantly associated with the cardiovascular risk factors among elderly people.

Epidemiology of obesity in elderly people

Our study used data collected at Chung-Shing-Shin-Tseun community in Taiwan in May 1998 to evaluate the relationship between obesity and the cardiovascular and sociodemographic risk factors in elderly people. Individuals aged 65 and over were recruited as study subjects. A total of 1093 persons, out of 1774 registered residents, were contacted in face-to-face interview. The response rate was 61.6 percent. However only 586 respondents took blood tests and completed questionnaires. Analysis in this study was based on these 586 subjects. The chi-square analysis and multivariate logistic regression were used to study the significant correlates of obesity. Our results showed that 66 percent were men and 34 percent were women. The mean age was 73.1 +/- 5.3 years. The overweight proportions were 24.8 percent in elderly men and 29.7 percent in elderly women. The obesity proportions were 12.7 percent in elderly men and 11.5 percent in elderly women. After controlling the other covariates, the multivariate logistic regression analysis showed that overweight and obesity were associated with hypertension, hypertriglyceridemia, and hyperglycemia. In conclusions, the prevalence of overweight and obesity is high in Taiwanese elderly people. Thus, it is necessary to evaluate other metabolic disorders if one metabolic abnormality is observed.

Hypercholesterolemia and its correlates in Taiwanese elderly people

BACKGROUND

Our study used data collected in Chung-Shing-Shin-Tseun community in Taiwan in May 1998 to evaluate the relationship between hypercholesterolemia and the cardiovascular and sociodemographic risk factors in elderly people.

METHODS

Individuals aged 65 and over were recruited as study subjects. A total of 1,093 persons, out of 1,774 registered residents, were contacted in face-to-face interview. The response rate was 61.6 percent. However, only 586 respondents took blood tests and completed questionnaires. Analysis in this study was based on these 586 subjects. The t-test, chi-square analysis, and multivariate logistic regression were used to study the significant correlates of hypercholesterolemia.

RESULTS

Our results showed that 66 percent were men and 34 percent were women. The mean age was 73.1 +/- 5.3 years. The mean total cholesterol value was 5.1 +/- 1 mmol/l in elderly men and 5.5 +/- 1.3 mmol/l in elderly women. The proportions of hypercholesterolemia were 43.7 percent in elderly men and 59.6 percent in elderly women. After controlling the other covariates, the multivariate logistic regression analysis showed that the significant related factors of hypercholesterolemia were age, hypertriglyceridemia, and hyperuricemia. No significant association was found between hypercholesterolemia and gender, obesity, high systolic pressure, high diastolic pressure, hyperglycemia, educational level, retirement status, or marital status.

CONCLUSION

Hypercholesterolemia is significantly associated with hypertriglyceridemia and hyperuricemia in elderly people. It is important to determine other metabolic disorders if one metabolic disorder is disclosed.

Age when maximum height is reached as a risk factor for breast cancer among young U.S. women

We evaluated height as a potential risk factor for breast cancer in a case-control study of 747 young women diagnosed with invasive breast cancer before age 46 years and 961 control subjects recruited by random digit dialing. We found that total height attained did not affect a woman's risk of the disease. The age when a women reached her maximum height, however, was a risk factor for breast cancer. There was a trend of decreasing risk of breast cancer in relation to increasing age of height attainment, culminating in a 30% reduction in the risk of breast cancer for women who reached their maximum height when they were 18 years or older compared with women who reached their maximum height when they were 13 years old or less (odds ratio = 0.7; 95% confidence interval = 0.5-1.0). Although the age at menarche was correlated with the age at maximum height, the effect of age at maximum height persisted after adjustment for age at menarche. Previous studies have reported that age at menarche is an important determinant of risk, but this study indicates that age when maximum height is reached may be another, and possibly more important, landmark of puberty that is related to breast cancer risk. The physiologic basis for this claim may lie in the influence on breast development of exposure to growth hormone and insulin-like growth factor during puberty, and on a decreased time between the end of puberty and a woman's first livebirth, both of which are believed to affect a woman's risk of breast cancer.

Serum and tissue levels of estradiol during estrogen-induced renal tumorigenesis in the Syrian hamster

The estrogen-induced renal tumor in the hamster has emerged as a major animal model in hormonal carcinogenesis. However, a fundamental aspect of this experimental model has as yet not been investigated. In the present study, comparisons between the serum and tissue 17 beta-estradiol (E2) levels in cyclic female hamsters and corresponding hormone levels in E2-treated castrated male hamsters have been made. Data is provided concerning the concentration of estrogenic hormones in the serum and target tissue typically required to elicit renal tumorigenesis in this species. Serum E2 levels in the cyclic female hamster average 79 pg/ml on days 1-2 and 311 pg/ml on days 3-4, attaining a maximum of 358 pg/ml on day 4 of the cycle. Elevation in uterine, renal and hepatic E2 tissue levels during days 3-4 of the cycle reflect increases in serum E2 levels which were 3.0-, 2.0-, and 2.6-fold higher when compared to day 1 of the cycle in these tissues. As expected, serum E2 levels of untreated castrated male hamsters did not appreciably vary over a 6 month period of aging and averaged about 32 pg/ml. Under conditions which produced essentially 100% renal tumor incidence, a rapid rise in serum E2 levels, averaging 71.0-fold higher than untreated castrated levels, was seen. A steady state serum E2 level of 2400 to 2700 pg/ml was maintained from 45-180 days of continuous estrogen treatment. Compared to kidneys of untreated hamsters, renal E2 levels in E2-treated hamsters rose only on average 5.4-fold between 15-180 days of hormone exposure. Serum levels of E2-treated hamsters were 5.7- to 8.0-fold higher than those observed in cyclic female hamsters on days 3 and 4. However, at these higher E2-treated serum levels there was no apparent effect either on weight loss or mortality of the animals.

Role of sustained neurones of cat lateral geniculate nucleus in processing luminance information

The properties of the sustained cells in the lateral geniculate nucleus of cat have been studied quantitatively. These cells may be subdivided into two groups, the brightness and the darkness detectors. The former is photoexcitatory neurone and the latter, photoinhibitory. In both types, the rates of sustained discharges are closely related to the levels of retinal illumination over a range about 4 log units. The receptive fields of sustained cells again can be roughly divided into two subtypes according to their size. The large receptive field cells all belong to darkness detectors and are distributed mostly at retinal periphery, which may play some role in signalling the background luminance. The small receptive field cells comprise all brightness detectors and a part of darkness detectors, which are located predominantly around area centralis and may transmit the message of brightness or darkness about picture details and enhance the boundaries of a two-dimensional figure.