Use of XTT for quantitating clonogenic growth in soft agar.

The purpose of this study was to investigate the use of the tetrazolium salt. XTT, in a microassay for quantitation of anchorage-independent growth of cells in soft agar, using two human ovarian tumour cell lines (OAW 42 and OAW 28). The response of OAW 42 to Cis-platinum, EGF, TGF ß and insulin, and of OAW 28 to EGF, TGF ß and insulin were determined both by visual colony counting and use of the XTT assay. Drug inhibition and growth factor inhibition and stimulation were clearly demonstrated, with increases or decreases in visually counted colony numbers being paralleled by increases or decreases in optical density values obtained by using XTT. The XTT colorimetric assay was simple to perform and reproducible with low variability, and was found to be an acceptable alternative to visual colony counting for the quantitation of cell line response to drugs and growth factors under anchorage-independent growth conditions.

The methylene blue colorimetric microassay for determining cell line response to growth factors.

The validity of the methylene blue colorimetric microassay for determining the response of monolayers of human ovarian tumour cell lines to different growth factors was investigated. Linearity of the relationship between cell density and optical density was confirmed for each cell line (r=0.989-0.999,p<0.001), and when initial cell density was optimised to give exponential growth over the assay period, differences in response to medium supplements were obvious. The response of target cells to growth factors, obtained using the methylene blue assay, were compared with, and found to parallel, previously documented responses obtained non-colorimetrically. Thus Mink lung epithelial cells (MLEC) were inhibited by TGß (Holleyet al., 1983), EGF had an inhibitory effect on A431 cells (Gill & Lazar, 1981; Barnes, 1982), and the mesothelial cell line showed a proliferative response to EGF and hydrocortisone (Connell and Rheinwald, 1983).The methylene blue colorimetric microssay was found to be a simple, reliable, sensitive method with low variability, for determining the response of cultured cells to growth factors.

Attitudes, knowledge, and training of medical residents regarding adolescent health issues.

This study examined attitudes, knowledge, and training relating to adolescent health issues, of medical residents in six different specialties who provide care to adolescents, at a southern, rural medical school without an organized curriculum in adolescent medicine. An original 18-item questionnaire was developed which examined four broad health care categories: general medicine, sexuality, high-risk behaviors, and development. Of 118 residents 91 (77%) responded. For any health care area, residents reported managing fewer than 10 adolescent patients and often fewer than 3 patients. However, they reported comfort and confidence and little desire for additional training in most of these areas. There were few differences between specialties or year of training. Almost one-half (42%) believed that pediatric care should end by age 16 years; 32% thought it should end at age 18 years. However, there was little support for pediatricians providing prenatal care to pregnant teens. These findings are useful for planning curriculum in ambulatory adolescent health and developing strategies for encouraging residents to understand and embrace the challenge of adolescent health care.

The effects of number of trials per day, retention interval, gender and time of day on acquisition of a two-choice, win-stay water-escape working memory task in the rat.

A 2 x 2 x 2 factorial study was conducted to examine the effects of gender, trials/day (TPD), and retention interval (RI) on acquisition of a two-choice win-stay water-escape task in 4-month-old Sprague-Dawley rats. Variations of this task have previously been shown to be sensitive to changes in working memory that occur with age (Means and Kennard, 1991) or to follow treatment with an anxiolytic (Bass et al., 1989) or with cognitive enhancers (Comer and Moore, in press) in males or to estrogen in ovariectomized females (O'Neal et al., 1990). Both training with 1 TPD and with a 5-min RI, time between an information "run" and a test "run", reduced errors during acquisition as compared to giving 3 TPD and a 1-min RI (P less than 0.05 in all cases). Males made fewer errors than did females (P less than 0.05). The three effects were additive: males trained with 1 TPD and a 5-min RI performed best and females trained with 3 TPD and a 1-min RI performed worst. Also, rats given 1 TPD made fewer acquisition errors when trained 2 h before the lights were turned off than when trained during the middle of the light portion of the light/dark cycle (P less than 0.05). Finally, when given 3 TPD, the rats, especially the females, performed significantly worse on their third trial (P less than 0.05). It was concluded that two-choice win-stay water-escape is a very sensitive assay of working memory with much potential for neurobehavioral research.