Unlocking the secrets of galectins: a challenge at the frontier of glyco-immunology

Over the last decade, we have witnessed an explosion of information regarding the function of glycoconjugates, carbohydrate-binding proteins, and the elucidation of the sugar code. This progress has yielded not only important insights into fundamental areas of glycobiology but has also influenced other fields such as immunology and molecular medicine. A family of galactoside-binding proteins, called galectins, has emerged recently as a novel kind of bioactive molecules with powerful, immunoregulatory functions. Different members of this family have been shown to modulate positively or negatively multiple steps of the inflammatory response, such as cell-matrix interactions, cell trafficking, cell survival, cell-growth regulation, chemotaxis, and proinflammatory cytokine secretion. To introduce a comprehensive overview of these new advances, here we will explore the molecular mechanisms and biochemical pathways involved in these functions. We will also examine the role of these proteins in the modulation of different pathological processes, such as chronic inflammation, autoimmunity, infection, allergic reactions, and tumor spreading. Understanding the intimate mechanisms involved in galectin functions will help to delineate selective and novel strategies for disease intervention and diagnosis.     

Apparent mitochondrial asymmetry in Xenopus eggs.

Cell polarity is manifest along the animal/vegetal axis in eggs of the frog, Xenopus laevis. Along this axis, maternal cytoplasmic components are asymmetrically distributed and are thought to underlie specification of distinct cell fates. To ascertain the molecular identities of such cytoplasmic components, we have used a monoclonal antibody that specifically stains the vegetal hemisphere of Xenopus eggs. The antigenic protein Vp67 (vegetal protein of 67 kDa) was identified through purification and cloning as a Xenopus homolog of the mitochondrial protein dihydrolipoamide acetyltransferase, a component of the pyruvate dehydrogenase complex. The identification of Vp67 as a mitochondrial protein could indicate that populations of mitochondria are asymmetrically distributed in Xenopus eggs.     

Mutations of the GREAT gene cause cryptorchidism

In humans, failure of testicular descent (cryptorchidism) is one of the most frequent congenital malformations, affecting 1-3% of newborn boys. The clinical consequences of this abnormality are infertility in adulthood and a significantly increased risk of testicular malignancy. Recently, we described a mouse transgene insertional mutation, crsp, causing high intraabdominal cryptorchidism in homozygous males. A candidate gene Great (G-protein-coupled receptor affecting testis descent), was identified within the transgene integration site. Great encodes a seven-transmembrane receptor with a close similarity to the glycoprotein hormone receptors. The Great gene is highly expressed in the gubernaculum, the ligament that controls testicular movement during development, and therefore may be responsible for mediating hormonal signals that affect testicular descent. Here we show that genetic targeting of the Great gene in mice causes infertile bilateral intraabdominal cryptorchidism. The mutant gubernaculae fail to differentiate, indicating that the Great gene controls their development. Mutation screening of the human GREAT gene was performed using DHPLC analysis of the genomic DNA from 60 cryptorchid patients. Nucleotide variations in GREAT cDNA were found in both the patient and the control populations. A unique missense mutation (T222P) in the ectodomain of the GREAT receptor was identified in one of the patients. This mutant receptor fails to respond to ligand stimulation, implicating the GREAT gene in the etiology in some cases of cryptorchidism in humans.     

Tetrasomy 12pter-12p13.31 in a girl with partial Pallister-Killian syndrome phenotype

A dysmorphic patient was shown to carry a small supernumerary marker chromosome. Multicolor, centromere-multicolor and regular FISH experiments proved the marker to be an analphoid 12pter derived isochromosome. Microdissection of the marker followed by reverse painting and array CGH analysis showed that the isochromosome contains approximately 6 Mb of 12pter-12p13.31 derived sequence. This is only the second report of a marker with a neocentromere 12pter and the molecular fine mapping of the duplicated region further refines the 12p region defining the Pallister-Killian syndrome phenotype. In addition, we show the feasibility of using microdissected chromosomes or chromosomal fragments to molecularly map the chromosomal breakpoints on array CGH. This technology may aid in the identification of chromosomal translocation breakpoints.     

Anna's story: a qualitative analysis of an at-risk mother's experience in an attachment-based foster care program

This study chronicles an at-risk mother's experience in an alternative foster care program. Influenced by attachment theory, the Children's Ark reunited children with their mothers in a supervised home environment while also providing residential support, intensive therapy, and education. After losing custody of her infant Kindra, 18-year-old Anna participated in the Ark for 2 years, after which she regained custody of Kindra. We assessed Anna and Kindra at multiple times using a variety of instruments, including a semi-structured interview, the Adult Attachment Interview, and the Strange Situation procedure. Anna moved from a profoundly insecure state of mind to a secure one, while Kindra moved from a resistant to a secure attachment. Qualitative analyses of Anna's interviews documented growth in her capacity to use the important relationships at the Ark as secure bases and to welcome rather than fear intimacy with Kindra. The qualitative analyses also described growth in Anna's capacities for reflective functioning and positive changes in her internal working model. We conclude with an analysis of the process of change from the perspective of attachment theory.     

Distinct pathways for constitutive endocytosis of fully conformed and non-conformed L(d) molecules

PROBLEM: To characterize the constitutive internalization of major histocompatibility complex (MHC) class I molecules, we have studied the expression of completely conformed (full) and unconformed (empty) L(d) molecules on non-polarized murine P815 cells. METHODS OF STUDY: Spontaneous endocytosis of L(d) molecules was induced by cycloheximide, an inhibitor of protein synthesis, and their disappearance from the cell surface was determined by flow cytometry. In order to investigate the mechanism of internalization, a palette of inhibitors of endocytosis and vesicular transport was used. RESULTS: Inhibitors of clathrine endocytosis did not influence the internalization of L(d) molecules. Inhibitors of caveolar endocytosis and inhibitors of endolysosomal degradation prevented down-regulation of empty, but not of full L(d) molecules. CONCLUSIONS: Empty L(d) molecules are internalized mostly by caveolar endocytosis and full L(d) molecules use a different pathway, neither clathrine-mediated nor caveolar. After internalization, full L(d) molecules are probably degraded and empty L(d) molecules recycle between endosomal compartment and the cell surface before they enter into the degradation compartment.     

Metabolism in perfused rat lived at different terms after short-term hyperthermia

The metabolic state of rat liver was studiedin vivo 1, 6, and 18 h after single hyperthermia (42°C). It was shown that intracellular compensatory reactions involved in restoration of the energy state and realization of endogenous cytoprotective mechanisms play a role during recovery. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 4, pp. 414–416, April, 2000     

Energy metabolism of maternal and fetal tissues during adaptation to intermittent experimental normobaric hypoxia

Energy metabolism of maternal and fetal tissues in adaptation to intermittent normobaric hypoxia was studied in experiments on 72 female Wistar rats. During pregnancy the intensity of tissue respiration in myometry was more than twice that in a nonpregnant uterus. The rate of tissue respiration in vital organs (brain) remained at a high level irrespective of exposure to the effect of a gas hypoxic mixture containing 10% oxygen, i.e. the organism of the mother and fetus provides the developing brain with an optimum amount of oxygen even in its possible deficiency. Thus, adaptation of the maternal and fetal organism to GHM-10 is attended by some shifts in energy metabolism which maintain the aerobic oxidation metabolism in the studied tissues for a long duration through more effective consumption of oxygen in its lack.     

Assessment of the state of the myocardium from the histochemical detection of dehydrogenases in the presence of granular diformazan

Histochemical tests for dehydrogenases in isolated rat myocardia have shown the level of granular diformazan to correlate with the presence of fat drops in cardiomyocytes. Using a semiquantitative method they developed for assessing myocardial status from histochemical tests for dehydrogenases (glutamate, isocitrate, lactate, succinate, beta-hydroxybutyrate NADH, or NADPH dehydrogenases), the authors found that demonstration of granular diformazan in such tests is not associated with alterations in the state of particular dehydrogenases but is indicative of fatty dystrophy.