Groups perform better than the best individuals on letters-to-numbers problems: effects of group size.

Individuals and groups of 2, 3, 4, or 5 people solved 2 letters-to-numbers problems that required participants, on each trial, to identify the coding of 10 letters to 10 numbers by proposing an equation in letters, receiving the answer in letters, proposing a hypothesis, and receiving feedback on the correctness of the hypothesis. Groups of 3, 4, and 5 people proposed more complex equations and had fewer trials to solution than the best of an equivalent number of individuals. Groups of 3, 4, and 5 people had fewer trials to solution than 2-person groups but did not differ from each other.

Birth weight and breast cancer risk.

Exploring whether the positive association between birth weight and breast cancer risk differs by other breast cancer risk factors may help inform speculation about biological mechanism. In these data, high birth weight was associated with breast cancer risk in younger and in more educated women, but was not associated overall.

Reproductive outcomes in men with prenatal exposure to diethylstilbestrol.

Objective: To examine prenatal diethylstilbestrol (DES) exposure in relation to male reproductive outcomes.

Design: Prospective observational study.

Setting: Participants were identified through record review, clinical trial participation, or an obstetrics clinic.

Validation of large particle flow cytometry for the analysis and sorting of intact pancreatic islets.

Background: Accurate quantification of total islet yield is an essential step prior to transplantation and for research. The standard method of manually determining an islet equivalent (IEQ) count is subjective and prone to error. We evaluated Complex Object Parametric Analyzer and Sorter (COPAS) large particle flow cytometry for the determination of islet equivalent counts and purities of islet preparations.

Breast cancer incidence in women prenatally exposed to maternal cigarette smoke.

Background: Clinical studies show that maternal cigarette smoking reduces pregnancy estrogen levels. Women prenatally exposed to maternal cigarette smoke may, therefore, have a lower breast cancer risk because the fetal mammary gland's exposure to maternal estrogen is decreased. Associations between prenatal maternal cigarette smoke exposure and breast cancer, however, have not been observed in previous case-control studies that relied on exposure assessment after the onset of cancer.

Maternal smoking during pregnancy and risk of brain tumors in the offspring. A prospective study of 1.4 million Swedish births.

Objective: Studies of the effect of maternal smoking during pregnancy on development of brain tumors in the offspring generally have found no increase in risk but most have mainly relied on retrospective exposure assessment. We conducted a prospective study on a large birth cohort in Sweden.

Methods: Women giving birth during 1983-1997 were classified as smokers or non-smokers based on information ascertained at the first prenatal visit and recorded in the Swedish Birth Register.

Self-reported electrical appliance use and risk of adult brain tumors.

Electrical appliances produce the highest intensity exposures to residential extremely low frequency electromagnetic fields. The authors investigated whether appliances may be associated with adult brain tumors in a hospital-based case-control study at three centers in the United States from 1994 to 1998. A total of 410 glioma, 178 meningioma, and 90 acoustic neuroma cases and 686 controls responded to a self-administered questionnaire about 14 electrical appliances.

Risk of benign gynecologic tumors in relation to prenatal diethylstilbestrol exposure.

Objective: To investigate the association between prenatal diethylstilbestrol (DES) exposure and risk of benign gynecologic tumors.

Methods: We conducted a collaborative follow-up study of women with and without documented intrauterine exposure to DES. We compared the incidence of self-reported ovarian cysts, paraovarian cysts, and uterine leiomyomata confirmed by medical record in DES-exposed and unexposed women.

Reproductive and hormonal factors and risk of brain tumors in adult females.

Causes of brain tumors are largely unknown, and there is an urgent need to identify possible risk factors. Several observations point to a possible role of reproductive hormones, but few epidemiologic studies have examined whether reproductive factors, such as age at menarche and parity, are associated with brain tumor risk. We conducted a multi-center case-control study of newly diagnosed glioma (n = 212) and meningioma (n = 151) and frequency-matched controls (n = 436) in women from hospitals in Phoenix, Arizona; Boston, Massachusetts; and Pittsburgh, Pennsylvania between 1994 and 1998.

Expression of mouse fibroblast growth factor and fibroblast growth factor receptor genes during early inner ear development.

The inner ear, which mediates hearing and equilibrium, develops from an ectodermal placode located adjacent to the developing hindbrain. Induction of the placode and its subsequent morphogenesis and differentiation into the inner ear epithelium and its sensory neurons, involves signalling interactions within and between otic and non-otic tissues. Several members of the fibroblast growth factor (FGF) family play important roles at various stages of otic development; however, there are additional family members that have not been evaluated.

Sociodemographic indicators and risk of brain tumours.

Background: To better understand patterns of occurrence or diagnosis of brain tumours in different segments of the population, we evaluated associations between sociodemographic variables and the relative incidence of brain tumours as part of a multi-faceted case-control study.

Methods: The study was conducted at hospitals in three US cities between 1994 and 1998. In all, 489 glioma cases (354 high-grade, 135 low-grade), 197 meningioma cases, 96 acoustic neuroma cases, and 799 controls admitted to the same hospitals for any of a variety of non-neoplastic diseases or conditions were enrolled and interviewed.

Laterality of brain tumors.

Tumor laterality was evaluated with respect to presenting symptoms and demographic factors among 489 adults with histologically confirmed glioma (354 high-grade, 135 low-grade), 197 with meningioma, and 96 with acoustic neuroma. The ratio of left-sided to right-sided tumors did not differ significantly from 1.00 for any of the major tumor types.

Psychosexual characteristics of men and women exposed prenatally to diethylstilbestrol.

Background: Between 1939 and the 1960s, the synthetic estrogen diethylstilbestrol (DES) was given to millions of pregnant women to prevent pregnancy complications and losses. The adverse effects of prenatal exposure on the genitourinary tract in men and the reproductive tract in women are well established, but the possible effects on psychosexual characteristics remain largely unknown.

Methods: We evaluated DES exposure in relation to psychosexual outcomes in a cohort of 2,684 men and 5,686 women with documented exposure status.

Risk of breast cancer in women exposed to diethylstilbestrol in utero: prelimiinary results (United States).

Background: A synthetic estrogen, diethylstilbestrol (DES), was widely prescribed to pregnant women during the 1950s and 1960s but was later discovered to be associated with an increased risk of clear-cell carcinoma of the vagina and cervix in female offspring. DES has not been linked to other cancers in female offspring, but studies of other prenatal factors such as twin gestation and pre-eclampsia have indicated that in-utero estrogen levels may influence breast cancer risk. We evaluated the relation of in-utero DES exposure to the risk of adult breast cancer.

Magnetic fields produced by hand held hair dryers, stereo headsets, home sewing machines, and electric clocks.

A recent epidemiologic study reported associations between leukemia risk in children and their personal use of television (TV) sets, hair dryers, and stereo headsets, and the prenatal use by their mothers of sewing machines. To provide exposure data to aid in the interpretation of these findings, extremely and very low frequency (ELF and VLF) magnetic fields produced by a sample of each type of appliance were characterized in a field study of volunteers conducted in Washington DC and its Maryland suburbs. Questionnaire data regarding children's or mothers' patterns of usage of each type of appliance were also collected.

Incidence of squamous neoplasia of the cervix and vagina in women exposed prenatally to diethylstilbestrol (United States).

Objectives: Women exposed prenatally to diethylstibestrol (DES) have an excess risk of clear-cell adenocarcinoma of the vagina and cervix, but the effect on the incidence of squamous neoplasia is uncertain. The purpose of the current study was to evaluate the long-term risk of developing high-grade squamous neoplasia of the genital tract among women exposed prenatally to DES.

Methods: A cohort comprising 3,899 DES-exposed and 1,374 unexposed daughters was followed for 13 years (1982 1995) for pathology-confirmed diagnoses of high-grade squamous intraepithelial neoplasia (HSIL) of the genital tract.

Infertility among women exposed prenatally to diethylstilbestrol.

Although it is well established that women exposed to diethylstilbestrol in utero have an increased risk of spontaneous abortion, ectopic pregnancy, and preterm delivery, it is not known whether they also have an increased risk of infertility. The authors assessed this question in data from a collaborative follow-up study of the offspring of women who took diethylstilbestrol during pregnancy. In 1994, 1,753 diethylstilbestrol-exposed and 1,050 unexposed women from an ongoing cohort study (National Cooperative Diethylstilbestrol Adenosis Study and Dieckmann cohorts) provided data on difficulties in conceiving and reasons for the difficulty.

Static magnetic field measurements in residences in relation to resonance hypotheses of interactions between power-frequency magnetic fields and humans.

Bowman et al. used epidemiologic data to test a model in which subjects were classified as being "in-resonance" or "not-in-resonance" for 60-Hz magnetic-field exposures depending on single static magnetic-field measurements at the centers of their bedrooms. A second paper by Swanson concluded that a single static magnetic-field measurement is insufficient to meaningfully characterize a residential environment.

Household solvent exposures and childhood acute lymphoblastic leukemia.

Objectives: This study explored the risk of childhood acute lymphoblastic leukemia (ALL) associated with participation by household members in hobbies or other home projects involving organic solvents.

Methods: Participants in this case-control study were 640 subjects with ALL and 640 matched controls.

Results: Childhood ALL was associated with frequent (> 4 times/month) exposure to model building (odds ratio [OR] = 1.

Cancer risk in men exposed in utero to diethylstilbestrol.

Background: An association between prenatal diethylstilbestrol (DES) exposure and cancer in men, especially testicular cancer, has been suspected, but findings from case-control studies have been inconsistent. This study was conducted to investigate the association between prenatal DES exposure and cancer risk in men via prospective follow-up.

Methods: A total of 3613 men whose prenatal DES exposure status was known were followed from 1978 through 1994.

Cellular-telephone use and brain tumors.

Background: Concern has arisen that the use of hand-held cellular telephones might cause brain tumors. If such a risk does exist, the matter would be of considerable public health importance, given the rapid increase worldwide in the use of these devices.

Methods: We examined the use of cellular telephones in a case-control study of intracranial tumors of the nervous system conducted between 1994 and 1998.

Long-term cancer risk in women given diethylstilbestrol (DES) during pregnancy.

From 1940 through the 1960s, diethylstilbestrol (DES), a synthetic oestrogen, was given to pregnant women to prevent pregnancy complications and losses. Subsequent studies showed increased risks of reproductive tract abnormalities, particularly vaginal adenocarcinoma, in exposed daughters. An increased risk of breast cancer in the DES-exposed mothers was also found in some studies.

Do confounding or selection factors of residential wiring codes and magnetic fields distort findings of electromagnetic fields studies?

In contrast with several previous studies, our recent large case-control study found little association between childhood acute lymphoblastic leukemia (ALL) and electric-power-line wire codes. Here we examine internal evidence from our study to assess the possibility that selection bias and/or confounding may have affected the findings. We compared the relation between childhood ALL and wire codes and direct measurements of magnetic fields in subjects who participated in all phases of the study with the relation in all subjects, including those who declined to allow access inside the home.