Histological characterization of human breast implant capsules.

BACKGROUND: This study investigated the relationships between histomorphological aspects of breast capsules, including capsule thickness, collagen fiber alignment, the presence of α-smooth muscle actin (α-SMA)-positive myofibroblasts, and clinical observations of capsular contracture. METHODS: Breast capsule samples were collected at the time of implant removal in patients undergoing breast implant replacement or revision surgery. Capsular contracture was scored preoperatively using the Baker scale. Histological analysis included hematoxylin and eosin staining, quantitative analysis of capsule thickness, collagen fiber alignment, and immunohistochemical evaluation for α-SMA and CD68. RESULTS: Forty-nine samples were harvested from 41 patients. A large variation in histomorphology was observed between samples, including differences in cellularity, fiber density and organization, and overall structure. Baker I capsules were significantly thinner than Baker II, III, and IV capsules. Capsule thickness positively correlated with implantation time for all capsules and for contracted capsules (Baker III and IV). Contracted capsules had significantly greater collagen fiber alignment and α-SMA-positive immunoreactivity than uncontracted capsules (Baker I and II). Capsules from textured implants had significantly less α-SMA-positive immunoreactivity than capsules from smooth implants. CONCLUSION: The histomorphological diversity observed between the breast capsules highlights the challenges of identifying mechanistic trends in capsular contracture. Our findings support the role of increasing capsule thickness and collagen fiber alignment, and the presence of contractile myofibroblasts in the development of contracture. These changes in capsule structure may be directly related to palpation stiffness considered in the Baker score. Approaches to disrupt these processes may aid in decreasing capsular contracture rates. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The effects of sexual experience and estrus on male-seeking motivated behavior in the female rat.

Ovariectomized (OVX) female rats were trained to traverse a straight alley and return to a goal box where they had previously encountered a male rat, a female rat or an empty goal box. The time required to run the alley was used as an index of the subjects' motivation to re-engage the goal box target. Subjects were tested in both estrus and non-estrus, first sexually naïve and then again after sexual experience. Female rats ran most quickly for a male target, most slowly for an empty goal box, and at intermediate speeds for a female target. Sexual experience tended to slow run times for all but male targets. Estrus enhanced approach behavior for males and an empty goal box, but tended to slow the approach toward females, both before and after sexual experience. This latter finding was further investigated in a second experiment in which sexually naïve OVX females were tested during estrus and non-estrus in a locomotor activity apparatus, a runway with an empty goal box, and an open field. Estrus produced no changes in spontaneous locomotion either in the activity box or the open field, but decreased run times in the alley and increased the number of center-square entries in the open-field. Thus, estrus produces increases in sexual motivation that selectively enhance exploratory, presumably male-seeking behavior, but not simple spontaneous locomotion.

Estrogen abolishes latent inhibition in ovariectomized female rats.

Estrogen is frequently prescribed as a method of birth control and as hormone replacement therapy for post-menopausal women with varied effects on cognition. Here the effects of estrogen on attention were examined using the latent inhibition (LI) behavioral paradigm. Ovariectomized (OVX) female rats were given either estrogen benzoate (EB, 10 or 100 microg/ml/kg; SC) or sesame oil vehicle. Males and OVX females receiving vehicle displayed normal LI. In contrast, LI was abolished in OVX females receiving EB. The lack of LI in OVX females receiving EB was a result of low suppression ratios, reflecting strong conditioning between the tone and the shock in these subjects even if they were pre-exposed to the tone. Thus, estrogen impaired the ability of OVX females to ignore irrelevant stimuli. Since different cognitive tasks vary in their required ability to ignore irrelevant stimuli, these results may account for some of the variations in the current literature on estrogen and cognition.