MHC class II antigen expression in normal human epidermis

Monoclonal antibodies consistently demonstrated the presence of MHC class II antigens (HLA-DR,-DP and -DQ) on keratinocytes in normal human epidermis. Reactivity was normally greatest on the keratinocytes of the intraepidermal portion of sweat ducts or the external root sheath of hair follicles, but staining was noted on the surface of some interappendageal keratinocytes in most subjects. The patterns were varied but distinctive and depended on the antibody used. The functional importance of the MHC class II antigens expressed on normal keratinocytes remains to be investigated.     

Rats fed only during the light period are resistant to stress-induced weight loss

Repeated restraint stress (3 h/day for 3 days) causes a chronic down-regulation of body weight in rats. This study determined whether weight loss was influenced by the time of day that rats had access to food or that stress was applied. Groups of male Sprague-Dawley rats were fed a 40% kcal fat diet with food given ad libitum, only during the light phase or only during the dark phase. After 2 weeks of adaptation, rats within each feeding treatment were divided into four groups. One was exposed to repeated restraint at the start of the light phase, another was restrained at the start of the dark phase and the remaining groups were nonstressed controls for restrained rats. Body weight was significantly reduced in ad libitum- and dark-fed restrained rats, compared with nonstressed controls, from Day 2 of restraint, regardless of the time of day that they were stressed. There was no significant effect of restraint on weight change of light-fed rats. Food intake was inhibited by stress in ad libitum- and dark-fed rats, but it was not changed in light-fed rats. Serum corticosterone was increased by restraint in all rats irrespective of feeding schedule. This study demonstrates that stress-induced weight loss only occurs when rats have food available during their normal feeding period (dark phase) and is not determined by increased corticosterone release.     

Olfactory bulbectomy: emotional behavior and defense responses in the rat

Removal of the olfactory bulbs of male hooded rats caused a reduction in defensive reactions to an unconditioned aversive stimulus (mechanical robot). In the presence of the robot, bulbectomized rats showed significantly less freezing and significantly less suppression of feeding behavior than sham-operated controls. At the same time, the bulbectomized rats were significantly more irritable to handling and showed a significant increase in muricide. These effects could not be attributed to loss of olfactory perception alone. Rats made peripherally anosmic through surgical removal of olfactory afferents were virtually indistinguishable from controls. These results provide further evidence for the view that in addition to their sensory functions, the olfactory bulbs of the rat have important tonic influences on emotional behavior. These tonic influences can occur independently of sensory processing and seem to be critical for the normal expression of emotional behavior or defense responses in this animal.     

Chromosomal factors of infertility in candidate couples for ICSI: an equal risk of constitutional aberrations in women and men

To assess the frequency of chromosomal aberrations in French candidates for intracytoplasmic sperm injection (ICSI), and to explore the existence of a female chromosomal factor in some cases of couple infertility, a collaborative retrospective clinical and cytogenetic study was performed, launched by the Association des Cytogénéticiens de Langue Franciaise (ACLF). The karyotypes of 3208 patients [2196 men (68.4%), 1012 (31.6%) women] included in ICSI programmes over a 3-year period in France were collected. A total of 183 aberrant karyotypes was diagnosed, corresponding to an abnormality frequency of 6.1% (134/2196) for men and 4.84% (49/1012) for women. The following frequencies of abnormalities were observed respectively for men and women: 1.23% (n = 27) and 0.69% (n = 7) for reciprocal translocations, 0.82% (n = 18) and 0.69% (n = 7) for Robertsonian translocations, 0.13% (n = 3) and 0.69% (n = 7) for inversions, 3.32% (n = 73) and 2.77% (n = 28) for numerical sex chromosome aberrations, and 0.59% (n = 13) and 0% for other structural aberrations. Among the male patients of this latter group, 0.40% (n = 9) had a Y chromosome abnormality. Among the male patients with numerical sex chromosome abnormalities, 2.23% (n = 49) were 47,XXY, 0.32% (n = 7) were 47,XYY, and 0.77% (n = 17) had a mosaicism for numerical sex chromosome anomalies. All the female patients with sex chromosome abnormalities (2.77%, n = 28) had mosaicism for numerical sex chromosome anomalies. Even if these cases-the significance of which was sometimes questioned-were disregarded in the analysis, 2.08% (21/1012) of abnormal karyotypes remained in women. An overall increased frequency of chromosomal aberrations was found, and this confirmed that in some cases of poor reproductive outcome there may be a contribution of maternal chromosome aberrations. Indeed, the existence of a chromosome abnormality in the female partner was associated with the group of infertile men in which there was no apparent cause of infertility.