Deletion of the mental retardation gene Gdi1 impairs associative memory and alters social behavior in mice

Non-specific mental retardation (NSMR) is a common human disorder characterized by mental handicap as the only clinical symptom. Among the recently identified MR genes is GDI1, which encodes alpha Gdi, one of the proteins controlling the activity of the small GTPases of the Rab family in vesicle fusion and intracellular trafficking. We report the cognitive and behavioral characterization of mice carrying a deletion of Gdi1. The Gdi1-deficient mice are fertile and anatomically normal. They appear normal also in many tasks to assess spatial and episodic memory and emotional behavior. Gdi1-deficient mice are impaired in tasks requiring formation of short-term temporal associations, suggesting a defect in short-term memory. In addition, they show lowered aggression and altered social behavior. In mice, as in humans, lack of Gdi1 spares most central nervous system functions and preferentially impairs only a few forebrain functions required to form temporal associations. The general similarity to human mental retardation is striking, and suggests that the Gdi1 mutants may provide insights into the human defect and into the molecular mechanisms important for development of cognitive functions.     

Morbidity in obese and nonobese patients following gynecologic surgery for cancer

Meager information exists regarding the morbidity of cancer surgery in obese patients, and it is generally assumed that surgery in the obese patient is attended with increased complications over those found in nonobese patients. A retrospective evaluation was undertaken at the Louisiana State University Medical Center to ascertain the morbidity of cancer surgery among 97 patients. In comparing the obese with the nonobese group of patients, the former was more often found to have complications of postoperative wound disorders that frequently required secondary operations, and a greater incidence of diabetes. The risk of postoperative complications among obese patients undergoing cancer surgery did not otherwise appear to be greater than that of nonobese patients.     

Antigenic interrelationships among mite allergens (Blomia andDermatophagoides spp)

Conclusions Asthma can occur as a result of allergy to both house dust mites and to storage mites. Many people worldwide are exposed to more than one mite species in the domestic environment. The most common domestic mites areD. pteronyssinus, D. farinae, E. maynei, andB. tropicalis; other storage mites are found in homes much less frequently, even in tropical climates. Because of the ready availability of allergen extracts for skin testing and immunotherapy, patients with respiratory symptoms are generally evaluated for sensitization toD. pteronyssinus andD. farinae only. The evidence reviewed here suggests, however, that, although there are crossreactive allergens between many mite species, most species have specific allergens that can be an important cause of IgE responses. Therefore, the role ofB. tropicalis andE. maynei in the etiology of asthma merits further investigation. Identification of species-specific and crossreactive allergens and production of recombinant allergens would be useful tools in allergy practice. By skin-testing patients, physicians would then be able to evaluate whether patients recognize crossreactive allergens or species-specific allergens and whether or not there is a need for immunotherapy to more than one mite species.     

Giant cell granuloma of the orbit with intracranial extension

An 8-year-old boy presented with acute proptosis of the right eye. Examination revealed 8 mm of exophthalmos, limitation of upward gaze, optic disc swelling, and normal visual acuity, but an inferonasal quadrantic visual field defect. Orbital ultrasound and computed tomographic scanning demonstrated a superotemporal tumor of the right orbit with intracranial extension. At operation, this proved to be a "reparative" giant cell granuloma. After partial resection, the remaining mass resolved spontaneously without further specific treatment. There had been no recurrence at the 1-year follow-up examination.     

An odor discrimination model with application to kin recognition in social insects

The problem of discriminating between a number of similar, nonspecific odors is discussed with special reference to the phenomenon of kin and nestmate discrimination in social insects. Guided by the basic physiological and anatomical features of the olfactory sensory receptors and neural pathways in insects, a model is presented for the process of odor discrimination. The model hypothesizes neural processing capabilities that include the logarithmic transformations of electrical potentials to generate a scalar quantity representing the "similarity" of two multivalued signals. The model thereby quantifies the notion of phenotype matching that appears in the kin recognition literature, and makes the concept of a recognition template more precise. The hypotheses underlying the model suggest a number of neurophysiological studies that should be undertaken, while the model itself provides a basis for integrating several areas of research pertaining to kin recognition in particular species of animals.