Transplantation of fetal neocortex in rhesus monkey

A feasibility study of neural transplantation in adult rhesus monkey was undertaken. Fresh and preserved neocortex containing multiplying and maturing neurons obtained from 55–70 gestation days were transplanted into the striatum, cerebellum and cerebral cortex of adult monkeys. Tissues were preserved for 4 days either at subzero temperature in the freezer compartment of the ordinary refrigerator in Ringer lactate or incubated in culture medium. While 2 monkeys out of 5 injected with preserved tissue had successful transplants after 4 months, all the 10 monkeys injected with fresh tissue had no transplants. The size of the two surviving transplants was small. The neurons in the transplants were mainly in clusters. Many of the cells were immature and some showed early degenerative changes. Neuronal processes were restricted to the transplants and thus showed lack of morphological integration with the host tissue. Further studies are in progress to define the nature of the embryonic tissue of primate which can grow and survive and also the role of neural grafts in functional recovery following experimental lesions of the brain regions.     

Binding of Hyaluronan to the Native Lymphatic Vessel Endothelial Receptor LYVE-1 Is Critically Dependent on Receptor Clustering and Hyaluronan Organization

The lymphatic endothelial receptor LYVE-1 has been implicated in both uptake of hyaluronan (HA) from tissue matrix and in facilitating transit of leukocytes and tumor cells through lymphatic vessels based largely on in vitro studies with recombinant receptor in transfected fibroblasts. Curiously, however, LYVE-1 in lymphatic endothelium displays little if any binding to HA in vitro, and this has led to the conclusion that the native receptor is functionally silenced, a feature that is difficult to reconcile with its proposed in vivo functions. Nonetheless, as we reported recently, LYVE-1 can function as a receptor for HA-encapsulated Group A streptococci and mediate lymphatic dissemination in mice. Here we resolve these paradoxical findings and show that the capacity of LYVE-1 to bind HA is strictly dependent on avidity, demanding appropriate receptor self-association and/or HA multimerization. In particular, we demonstrate the prerequisite of a critical LYVE-1 threshold density and show that HA binding may be elicited in lymphatic endothelium by surface clustering with divalent LYVE-1 mAbs. In addition, we show that cross-linking of biotinylated HA in streptavidin multimers or supramolecular complexes with the inflammation-induced protein TSG-6 enables binding even in the absence of LYVE-1 cross-linking. Finally, we show that endogenous HA on the surface of macrophages can engage LYVE-1, facilitating their adhesion and transit across lymphatic endothelium. These results reveal LYVE-1 as a low affinity receptor tuned to discriminate between different HA configurations through avidity and establish a new mechanistic basis for the functions ascribed to LYVE-1 in matrix HA binding and leukocyte trafficking in vivo.     

Structure of the regulatory hyaluronan binding domain in the inflammatory leukocyte homing receptor CD44

Adhesive interactions involving CD44, the cell surface receptor for hyaluronan, underlie fundamental processes such as inflammatory leukocyte homing and tumor metastasis. Regulation of such events is critical and appears to be effected by changes in CD44 N-glycosylation that switch the receptor "on" or "off" under appropriate circumstances. How altered glycosylation influences binding of hyaluronan to the lectin-like Link module in CD44 is unclear, although evidence suggests additional flanking sequences peculiar to CD44 may be involved. Here we show using X-ray crystallography and NMR spectroscopy that these sequences form a lobular extension to the Link module, creating an enlarged HA binding domain and a formerly unidentified protein fold. Moreover, the disposition of key N-glycosylation sites reveals how specific sugar chains could alter both the affinity and avidity of CD44 HA binding. Our results provide the necessary structural framework for understanding the diverse functions of CD44 and developing novel therapeutic strategies.     

Biosynthesis of bakuchiol from cinnamic and p-coumaric acids

Specific incorporation of l-[U-¹⁴C]phenylalanine, [U-¹⁴C]cinnamic acid and p[2-¹⁴C]coumaric acid into bakuchiol has been observed in Psoralea corylifolia. Our findings show that the aromatic moiety along with two carbon atoms of the side chain are biosynthetically derived via phenylpropane pathway and not by the alternate pathway proposed earlier.     

Lithium-induced changes in the plasma and pituitary levels of luteinizing hormone,follicle stimulating hormone and prolactin in rats

Adult male Sprague-Dawley rats, maintained under a controlled photoperiod of LD 14:10 (white lights on at 06:00 h, CST), were injected with lithium chloride and changes in the levels of plasma and pituitary homogenates of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (PRL) were examined to evaluate the effects of this anti-manic drug on reproductive function. Two groups of rats were injected with lithium chloride intraperitoneally, twice daily at 09:00 and 16:00 h, for 2 and 7 days at a dosage of 2.5 meg/Kg body weight. Plasma and pituitary levels of LH, FSH and PRL were measured by radioimmunoassay. Plasma levels of LH were significantly (P<0.05) increased after 2 days of lithium treatment. In contrast, a significant (P<0.005) reduction in plasma levels of LH was evident when lithium injections were continued for 7 days. The plasma levels of FSH remained unaffected by lithium treatment by either time period. Lithium administered for 2 days did not bring about any significant alteration in the plasma levels of PRL, although there was a significant (P<0.002) reduction in plasma PRL levels after 7 days treatment. The concentrations of pituitary LH, FSH and PRL remained unchanged after 2 and 7 days of lithium treatment.     

Mathematical Modelling of Lipase Catalysed Resolution of O-Acetyl and O-Formyl Derivatives of Secondary Alcohols

Lipase catalysed transesterification of O-acetyl and O-formyl derivatives of several sterically hindered secondary alcohols with n-butanol is studied. The reaction is mathematically modelled and the rate constants in the model are evaluated by transient parameter estimation procedure. Several models are considered for predicting the enantiomeric excess (ee) of the product and compared with experimental observations. It is found that the maximum ee depends only on the rate constants of the two competing reactions and not on the order of reaction. A second order model is found to predict the observed behaviour well. When the data is fitted to an equilibrium type of model developed by Chen et al. (1987), it is found that the rate of forward reaction is several orders of magnitude larger than the rate of reverse reaction. The effect of acetyl and formyl groups on the reactivity and selectivity are also discussed.     

Molecular species of phosphatidylcholine in abetalipoproteinemia: effect of lecithin:cholesterol acyltransferase and lysolecithin acyltransferase

In order to study the role of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) in determining the molecular species composition of phosphatidylcholine (PC) and the specificity of lecithin:cholesterol acyltransferase (LCAT) in human plasma, we studied the PC species composition in plasma from abetalipoproteinemic (ABL) and control subjects before and after incubation at 37 degrees C. The ABL plasma contained significantly higher percentages of sn-2-18:1 species (16:0-18:1, 18:0-18:1, and 18:1-18:1) and lower percentages of sn-2-18:2 species (16:0-18:2, 18:0-18:2, and 18:1-18:2) as well as sn-2-20:4 species (16:0-20:4, 18:0-20:4, and 18:1-20:4). Similar abnormalities were found in the PC of ABL erythrocytes, while the PE of the erythrocytes was less affected. The relative contribution of various PC species towards LCAT reaction in ABL plasma was significantly different from that found in normal plasma. Thus, while 16:0-18:2 and 16:0-18:1 contributed, respectively, 43.8% and 15.9% of the total acyl groups used for cholesterol esterification in normal plasma, they contributed, respectively, 21.5% and 37.9% in ABL plasma. The relative contribution of 16:0-20:4 was also significantly lower in ABL plasma (4.7% vs. 9.0% in normal), while that of 16:0-16:0 was higher (6.4% vs. 0.5%). However, the selectivity factors of various species (percent contribution/percent concentration) were not significantly different between ABL and normal plasma, indicating that the substrate specificity of LCAT is not altered in the absence of VLDL and LDL. Incubation of ABL plasma in the presence of normal VLDL or LDL resulted in normalization of its molecular species composition and in the stimulation of its LCAT activity. Addition of LDL, but not VLDL, also resulted in the activation of lysolecithin acyltransferase (LAT) activity. The incorporation of [1-14C]palmitoyl lysoPC into various PC species in the presence of LDL was similar to that observed in normal plasma, with the 16:0-16:0 species having the highest specific activity. These results indicate that the absence of apoB-containing lipoproteins significantly affects the molecular species composition of plasma PC as well as its metabolism by LCAT and LAT reactions.