Mouse Model of Chronic Social Stress-Induced Excessive Pavlovian Aversion Learning-Memory.

Increased experience of aversive stimuli/events is a psychological-neurobiological state of major importance in psychiatry. It occurs commonly in generalized anxiety disorder, post-traumatic stress disorder, and major depression. A sustained period of exposure to threat (chronic stressor) is a common risk factor, and a major symptom is generalized excessive perception of, and reactivity to, aversive stimuli. In rodents, Pavlovian aversion learning and memory (PAL, PAM), quantified in terms of the conditioned defensive behavior freezing, is an extensively studied behavioral paradigm, and well understood in terms of underlying neural circuitry. In mice, chronic social stress (CSS) is a 15-day resident-intruder paradigm in which C57BL/6 adult males are exposed continuously and distally to dominant-aggressive CD-1 male mice (sustained threat) interspersed with a brief daily period of proximal attack (acute threat). To ensure that physical wounding is minimized, proximal attacks are limited to 30 to 60 s/day and lower incisor teeth of CD-1 mice are blunted. Control (comparison) mice are maintained in littermate pairs. The CSS and CD-1 mice are maintained in distal contact during subsequent behavioral testing. For PAL, CSS and control (CON) mice are placed in a conditioning chamber (context) and exposed to a tone [conditioned stimulus (CS)] and mild, brief foot shock [unconditioned stimulus (US)]. For PAM, mice are placed in the same context and presented with CS repetitions. The CSS mice acquire (learn) and express (memory) a higher level of freezing than CON mice, indicating that CSS leads to generalized hypersensitivity to aversion, i.e., chronic social aversion leads to increased aversion salience of foot shock. Distinctive features of the model include the following: high reproducibility; rare, mild wounding only; male specificity; absence of "susceptible" vs "resilient" subgroups; behavioral effects dependent on continued presence of CD-1 mice; and preclinical validation of novel compounds for normalizing aversion hypersensitivity with accurate feedforward prediction of efficacy in human patients. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Chronic social stress (CSS) Basic Protocol 2: Pavlovian aversion learning and memory (PALM).

Specimen radiographs assist in identifying and assessing resection margins of occult breast carcinomas.

For carcinoma specimens with non-grossly identifiable lesions such as microcalcifications, difficulties may be encountered in locating these abnormalities and sampling the margins that are at risk. This is magnified in the case of skin-sparing procedures where the margin is a much greater surface area and is the operation of choice in patients with diffuse microcalcifications and/or multifocal in situ disease. The objective of this study was to determine the efficacy of specimen radiographs of mastectomy in identifying occult carcinoma associated with microcalcifications and assessing the resection margins. We reviewed the histology and corresponding specimen radiographs of 16 patients with diffuse and widespread microcalcifications and who underwent skin-sparing mastectomy. After the specimens were serially sectioned, specimen radiographs of each section of the specimens were obtained with digital mammography equipment. Findings in the specimen radiographs were used to direct the histologic sampling of the specimens. On gross examination, two (12.5%) mastectomy specimens had identifiable discreet masses; the lesions were 4 and 7 mm, respectively. Histologic examination revealed the presence of carcinoma in 13 (81%) cases; seven with both infiltrating and in situ carcinoma and six with in situ carcinoma alone. The remaining three patients demonstrated only changes of biopsy site without any residual carcinoma. Microcalcifications were associated with in situ carcinoma in all malignant cases. Among the 12 cases with microcalcifications present at or within 2 mm of the margins, in situ carcinoma was present at the margins in three cases and located within 2 mm of the margins in two cases. All margins were negative in all cases with microcalcifications that were at least 1 cm away from the resection margins. The average number of tissue blocks examined was 16.6 +/- 5.4. The average number of tissue blocks sampled among randomly selected mastectomy specimens was 15.2 +/- 5.4. There was no statistically significant difference in the number of blocks between mastectomy cases with specimen radiographs taken and those without (t-test). Our study suggests that specimen radiographs may assist in identifying occult breast carcinoma associated with microcalcifications and assessing the resection margins without increased sampling.

Low-cost phantom for stereotactic breast biopsy training.

OBJECTIVE: This article reports on the construction of a low-cost phantom to be used for training technologists, residents, and radiologists to perform stereotactic breast biopsy. The model is adaptable to a variety of biopsy devices and realistically simulates the aspects of stereotactic breast biopsy. CONCLUSION: We believe our model provides an excellent alternative to more expensive commercial products.