Female discrimination of male odors correlated with male genotype at the T locus: A response to T-locus or H-2-locus variability?

Female house mice (Mus musculus), derived from several populations of wild-caught mice, were tested for their ability to discriminate between males whose genotype at the T locus was +/+ and those whose genotype was +/t, using odor cues alone. Females spent more time near the odors or +/+ males than near the odors of +/t males. This preference was independent of the T-locus genotype of the female and the particular type of t allele carried by either the male or the female. A female's preference, however, did appear to be related to the genotype of her parents. Females with one +/t parent were more likely to prefer +/t males than were females whose parents were both +/+. In a second experiment 18 females were tested with odors from soiled bedding of recombinant males whose genotype varied at the T locus but who were similar at the H-2 locus. As a control, these 18 females were also tested with bedding of wild-derived +/+ and +/t^{w semilethal} males. Females tested with recombinant males preferred odors of males not carrying lethal t alleles over those of males carrying two lethal t alleles, indicating that T-locus variability, not H-2-locus variability, is responsible for odor differences between +/+ and +/t males. Female responses to odors of recombinanat males did not differ from those to odors of +/+ and +/t^{w semilethal} males. Responses of mice to odor differences associated with T-locus variability may have evolved independently of responses to odor variability associated with the H-2 locus.This work was supported by NIH Grant HD 15997-01.     

Electrical impedance measurement of the breast: effect of hormonal changes associated with the menstrual cycle

The purpose of this study was to evaluate the influence of hormonal factors on electrical impedance measurement with a new device TS2000, which is a new method in diagnosis of breast disease. Twenty-one healthy pre-menopausal women volunteers (aged 24–39 years) were examined with the TS2000 once/week for two menstrual cycles. On average, at least one spot was present in 47 % of images of women not taking oral contraceptives and in 44 % of women taking oral contraceptives (OC). The number of spots varied over the menstrual cycle and had a maximum in week 3 and week 5. We found that after 1 week only 15 % of spots were present and no spots persisted for three consecutive weeks. These data, if further supported by observations on other populations of women, show that false-positive results are common in pre-menopausal women; however, these false-positive spots do not persist for long periods of time. This information may provide a basis for discrimination between true-positive and false-positive spots on the TS2000 image, since the latter would be expected to disappear on short-term follow up. Received: 31 January 2000; Revised: 22 May 2000; Accepted: 24 May 2000     

Electrical impedance scanning as a new breast cancer risk stratification tool for young women

BACKGROUND: Electrical impedance scanning (EIS) measures changes in breast tissue associated with breast cancer (Br-Ca) development. The T-Scan(tm2000 (ED is designed to use EIS to identify women ages 30-39 with elevated risk of breast cancer (i.e., T-Scan+ women). AIM: To estimate the relative probability of breast cancer in a T-Scan+ woman compared to a randomly selected young woman. METHODS: A prospective, two-cohort trial was conducted in pre-menopausal women. The Specificity (S(p))-Cohort evaluated T-Scan specificity in 1,751 asymptomatic women ages 30-39. The Sensitivity)S(n))-Cohort evaluated T-Scan sensitivity in 390 women ages 45-30 scheduled for biopsy. Specificity, sensitivity, and conservative estimate of disease prevalence were used to calculate relative probability. RESULTS: In the S(p)-Cohort, 93 of 1,751 women were T-Scan+ (S(p) = 94.7%; 95% CI: 93.7-95.7%). In the S(n)-Cohort, 23 of 87 biopsy-proven cancers were T-Scan+ (S(n) = 26.4%; 95% CI: 17.4-35.4%). Given S(p) = 94.7%, S(n) = 26.4% and prevalence of 1.5 cancers/1,000 women (ages 30-39), the relative probability of a T-Scan+ woman having Br-Ca is 4.95: (95% CI: 3.16-7.14). CONCLUSION: EIS can identify a subset of young women with a relative probability of breast cancer almost five times greater than in the population of young women at-large. T-Scan+ women have a sufficiently high risk of Br-Ca to warrant further surveillance or imaging.     

Analysis of a genetic recognition system in wild house mice

Wild female house mice have strong preferences for odors of male mice whose t-complex genotype is +/+ rather than for males carrying deleterious mutations (+/t) at the t complex. In this review of a large number of studies examining the basis for this preference, we suggest the following: first, preferences of +/+ females are greatly influenced by environmental factors and probably do not have a large genetic component: second, preferences of +/t females are less dependent upon environmental factors and hence may have a strong genetic component: third, the lethal factors within the t complex are involved in both the production of the cue by males and the expression of the preference in females: and fourth, there may be a second gene or genes within the t complex involved in the expression of female preference.     

Responses of male mice to odors of females: Effects of T- and H-2-locus genotype

Male wild house mice (Mus musculus) were given a choice of odors of females whose T-locus genotype was +/ + or +/t. Males showed strong preferences for the odors of +/ + females. However, when males were tested with odors of recombinant females whose genotype differed at the T locus but which carried similar haplotypes at the H-2 locus, the preference for odors of +/+ females was not manifested. Consequently, differences in female odor production that are responsible for male odor preference are not due specifically to the female genotype at the T locus.This work was partially supported by NIH Grant HD R01 1997 and a BRSG Grant from Rutgers University.