The kisspeptin system of the human hypothalamus: sexual dimorphism and relationship with gonadotropin-releasing hormone and neurokinin B neurons.

Kisspeptin signaling via the kisspeptin receptor G-protein-coupled receptor-54 plays a fundamental role in the onset of puberty and the regulation of mammalian reproduction. In this immunocytochemical study we addressed the (i) topography, (ii) sexual dimorphism, (iii) relationship to gonadotropin-releasing hormone (GnRH) neurons and (iv) neurokinin B content of kisspeptin-immunoreactive hypothalamic neurons in human autopsy samples. In females, kisspeptin-immunoreactive axons formed a dense periventricular plexus and profusely innervated capillary vessels in the infundibular stalk. Most immunolabeled somata occurred in the infundibular nucleus. Many cells were also embedded in the periventricular fiber plexus. Rostrally, they formed a prominent periventricular cell mass (magnocellular paraventricular nucleus). Robust sex differences were noticed in that fibers and somata were significantly less numerous in male individuals. In dual-immunolabeled specimens, fine kisspeptin-immunoreactive axon varicosities formed axo-somatic, axo-dendritic and axo-axonal contacts with GnRH neurons. Dual-immunofluorescent studies established that 77% of kisspeptin-immunoreactive cells in the infundibular nucleus synthesize the tachykinin peptide neurokinin B, which is known to play crucial role in human fertility; 56 and 17% of kisspeptin fibers in the infundibular and periventricular nuclei, respectively, contained neurokinin B immunoreactivity. Site-specific co-localization patterns implied that kisspeptin neurons in the infundibular nucleus and elsewhere contributed differentially to these plexuses. This study describes the distribution and robust sexual dimorphism of kisspeptin-immunoreactive elements in human hypothalami, reveals neuronal contacts between kisspeptin-immunoreactive fibers and GnRH cells, and demonstrates co-synthesis of kisspeptins and neurokinin B in the infundibular nucleus. The neuroanatomical information will contribute to our understanding of central mechanisms whereby kisspeptins regulate human fertility.

Nutrition education and counseling: knowledge and skill levels expected by dietetic internship directors.

Development of nutrition education and counseling skills is important in the educational preparation of dietitians. A national survey of dietetic internship directors was conducted to determine competency levels expected of students at the start of an internship, internship training given, and further preparation students need in 32 knowledge/skills areas deemed essential for delivery of nutrition education and counseling services. Completed questionnaires were received from 66 of 102 (65%) internship directors surveyed. The majority of directors expected only basic preparation for group nutrition education and individual counseling knowledge/skills areas. Internship training in nutrition education competencies was "moderate" to "extensive," whereas preparation in nutrition counseling competencies was more likely to be "extensive." Directors perceived the internship to provide adequate preparation in all but the advanced practice skills, such as behavior modification and motivational strategies, for which further preparation was recommended. The majority of internship directors reported that more than 25% of the intern practice experience was in patient counseling, with less experience in group instruction. Implications for undergraduate dietetic education are discussed in relation to internship directors' expectations as well as to present and future trends in the dietetic profession.

Nutrition for the elderly.

Nutrition in the older person is complex because of changing physiology, changes caused by multiple chronic diseases, changes induced by pharmacologic agents, and commonly, failing protein/caloric intake. This article is designed to explain the mechanisms of these processes and to suggest pragmatic and practical responses in the management of the older patient.