The role of examples and rules in the acquisition of a cognitive skill

In 3 experiments, participants memorized 8 examples, each exemplifying a different rule. Participants were asked to extend these rules to new examples. They practiced applications of the rules to examples over a period of 4 days (Experiment 1) or 5 days (Experiments 2 and 3). Although these rules were bidirectional, an asymmetry gradually built up such that participants became more facile in using the rules in the practiced direction. Participants also showed an advantage when the initial study example was repeated or when test examples were repeated. It is argued that skill acquisition involves development of a complex set of strategies based on use of rules and retrieval of examples. Four overlapping stages of skill acquisition are described.     

Microsatellite loci for stringless bees

What ethical concerns regarding the application of new antidementia compounds are pertinent to the best interests of patients with Alzheimer's disease and their caregivers? Based on collected preliminary anecdotal accounts, these concerns are important and should be considered carefully by clinicians, researchers, and families.     

Clozapine reduces rehospitalization among schizophrenia patients

Diabetes mellitus positive for antibodies to glutamate decarboxylase is heterogeneous as far as the degree of impairment of endogenous insulin release, though antibodies to glutamate decarboxylase are the most useful marker for future insulin deficiency. To investigate what determines the prognosis of diabetes mellitus positive for antibodies to glutamate decarboxylase, we measured HLA-DRB1 alleles in three groups: 77 cases of insulin-dependent diabetes mellitus (IDDM), 44 of non-insulin-dependent diabetes mellitus (NIDDM) with secondary failure of oral hypoglycemic therapy, and 22 of NIDDM well controlled by diet and/or sulfonylurea agents. The proportion of susceptible and resistant alleles to IDDM determined the degree of insulin deficiency, and comparison of IDDM to NIDDM well controlled by diet and/or sulfonylurea agents revealed significant differences in DRB1*0405 (P < 0.05; RR = 2.82 and RR = 0.89, respectively) and DRB1*1502 (P < 0.001; RR = 0.02 and RR = 2.19, respectively). This study revealed that HLA-DRB1 alleles contribute to determining the prognosis of Japanese diabetes mellitus positive for antibodies to glutamate decarboxylase.     

Membrane-bound calmodulin in Xenopus laevis oocytes as a novel binding site for melatonin

Melatonin has been suggested as a physiological antagonist of calmodulin. In this work, we have characterized melatonin binding sites in Xenopus laevis oocyte membranes. Binding of [125I]melatonin by X. laevis oocyte membranes fulfills all criteria for binding to a receptor site. Binding was dependent on time, temperature, and membrane concentration and was stable, reversible, saturable, and specific. The binding site was also pharmacologically characterized. Stoichiometric studies showed a high-affinity binding site with a Kd of 1.18 nM. These data are in close agreement with data obtained from kinetic studies (Kd=0.12 nM). In competition studies, we observed a low-affinity binding site (Kd=63.41 microM). Moreover, the binding site was characterized as calmodulin. Thus, binding was dependent on calcium and blocked by anti-CaM antibodies in a concentration-dependent manner. Calmodulin inhibitor chlorpromazine also inhibited binding of the tracer. From these results, it is suggested that membrane-bound calmodulin acts as a melatonin binding site in Xenopus laevis oocytes, where it might couple cellular activities to rhythmic circulating levels of melatonin. This hypothesis correlates with the previous findings describing melatonin as a physiological antagonist of calmodulin.     

Decision-making in the treatment of subfoveal neovascularization in age-related macular degeneration. An analysis from the patient''s perspective

The human mineralocorticoid receptor of the steroid receptor family contains a modular structure with domain E which is considered to be a hormone binding domain. Recombinant protein approaches enabled us to clearly determine that this domain is also able to interact with F-actin (Kd about 2 microM) and G-actin. Moreover, it was revealed that this mineralocorticoid receptor domain/actin interaction was modulated by specific mineralocorticoid ligands. Agonist (aldosterone) steroid binding almost totally (91%) abolished the interaction with F-actin, while antagonist (progesterone) binding allowed more than 30% of this binding. Steroid modulation of the interaction between domain E and actin indicated that this actin binding is specific and could be essential for cellular mineralocorticoid receptor activity.     

Knowledge and attitudes toward sexuality in adolescents and their association with the family and other factors

Family structure and function and their association with knowledge and attitudes toward sexuality, contraception, and sexually transmitted diseases (STD) were studied in 918 students and 312 adolescents working in factories. Unmarried workers reported higher rates of sexual activity than did students (30.9% vs. 21.8%, p = .04 for males; 12.9% vs. 6.0%, p = .005 for females). Among sexually active males, 33.3% of students and 30.7% of workers used contraception, compared with 27.5% of female students and 9.5% of female workers. Workers were from larger families than students, and the male and female workers had lower scores for knowledge on sexuality, contraception, and STD than did students. Multiple stepwise regression showed that age and schooling of the parents were associated with knowledge and attitudes in the students. In workers, the position of the child in the family was a negative regressor for attitudes and knowledge on sexuality in males, and for knowledge on contraception and STD in females. In regard to family function, the significant factors were compromise between the parents, positive affective response, communication within the family, problem solution, and control of behavior. It was concluded that female workers are at higher risk for unwanted pregnancies and STD. The factors associated with knowledge and attitudes were age, schooling of the parents, mother working out of home, position of the adolescent in the family, and the diverse aspects of family function.     

Pathogenesis of Mycobacterium bovis infection in cattle

This paper reviews the pathogenesis of Mycobacterium bovis infection in cattle, focusing on aspects relating to the host rather than the organism. A broad concept of pathogenesis has been considered and information is presented on sources and routes of infection, as well as the immune responses and pathology. In addition, data is presented on the excretion of M. bovis from tuberculous cattle.