Evidence of Increased Gc: Actin Complexes in Pregnant Serum: A Possible Result of Trophoblast Embolism

ABSTRACT: The molecular configuration of group-specific component Gc protein in sera from pregnant and nonpregnant individuals was compared by analytical isoelectric focusing and by print immunofixation in conjunction with known standards of Gc:actin and Gc:vitamin D₃ complexes. These studies revealed that while complexes of Gc with actin and with vitamin D were detectable in small amounts in nonpregnant sera, much larger quantities of both types of complexes were consistently visualized in pregnancy. In addition, when actin was added to pregnant sera containing Gc:vitamin D₃ complexes, a third anodal complex was revealed which presented the molecular configuration of actin: Gc: vitamin D₃. These results demonstrate that Gc:actin complexes may be present under physiological circumstances in the circulation. Since large amounts of trophoblast enter the maternal circulation during both normal and abnormal human pregnancy, experiments were undertaken that showed that actin was released from isolated trophoblast membranes and also upon lysis of other viable cells under physiological conditions similar to those obtained in serum, and such actin complexed rapidly with Gc. Although the effects of this phenomenon upon the immunobiology of pregnancy are unknown, these findings are consistent with the concept that Gc protein may exert a “scavenger” function in mopping up actin released from damaged cells.     

Effects of methylprednisolone on the Fc-receptor function of human reticuloendothelial system in vivo

Abstract. To determine whether the Fc-receptor function of reticuloendothelial system (RES) is modified by corticosteroid administration, we studied the spleen to liver uptake ratios of autologous, ⁹⁹Tc-labelled heatdamaged or IgG-coated erythrocytes, injected intravenously into 10 normal volunteers, 4 h after receiving a single dose of 32 mg of methylprednisolone by mouth.
In standard conditions, quantitative scans indicated that the spleen to liver uptake ratios, calculated per unit area 40 min after the injection of labelled erythrocytes, were 13·4 ± 0·6 and 31·2 ± 1·5 (mean values ± -SEM), for the heat-damaged ( n = 7) and IgG-coated red cells ( n = 5) respectively. Four hours after corticosteroid administration, the spleen to liver uptake ratios were significantly reduced in five of ten volunteers. Abnormal ratios correlated with the Fc-receptor function of monocytes measured in vitro using IgG-coated erythrocytes. Indeed, 2–6 h after methylprednisolone was given, the Fc-receptor binding activity of monocytes isolated from the same five subjects was reduced by at least 50%, spontaneously returning to a rather normal value 4–6 h later. The C3-receptor binding activity of these monocytes remained normal, after otherwise identical experimental conditions.
These results show a transient, specific impairment of the Fc-receptor function of RES after methylprednisolone administration, and may therefore explain, in part, the infectious complications occurring in some patients treated by corticosteroids.     

A glucose transfer from membrane glycoconjugates to haemoglobin in isolated young red blood cells: another biosynthetic way for glycosylated haemoglobins

Abstract. Human red blood cells (RBC) are separated by centrifugation into young and old ones, as demonstrated by lower enzymatic activities and lower potassium content of the older ones. The young RBC fraction represents 5% of total RBC. After incubation for 24 h in a neutral buffer, the young RBC HbA_1c content increases significantly from 4·2 to 5·2% of total Hb. No increase is found in the case of old RBC. When young RBC have been extracted for 1 h by a neutral buffer prior to incubation, there is no more increase of HbA_1c.
The extract contains a glycoconjugate that is both soluble in neutral buffers and in chloroform. A glycolipid extractable from the young RBC membrane contributes to HbA_1c formation but disappears from old RBC, in which glycosylation by free glucose occurs. These processes are stereospecific.     

Synthesis of functionalized non-natural amino acid derivatives via amidoalkylation transformations

Synthetic routes have been developed for the preparation of functionalized amino acid derivatives in which the α-substituent at carbon 2 is either an aromatic or a heteroaromatic group. The α-substituent was introduced using an amidoalkylation reaction using boron trifluoride etherate and proceeded in moderate yield with excellent regioselectivity. This protocol permitted the employment of the acid sensitive heterocycles: pyrrole, benzofuran, and indole. The scope and limitations of this procedure have been evaluated.     

Antibodies against Echinococcus multilocularis alkaline phosphatase as markers for the specific diagnosis and the serological monitoring of Alveolar echinococcosis

The immunological properties of the purified alkaline phosphatase (pAP) of Echinococcus multilocularis metacestodes have been investigated using alveolar echinococcosis (AE) patient sera in ELISA tests. A comparative study was done with EmC-Ag (crude antigen) and pAP-Ag (purified antigen). When the parasite purified enzyme pAP was used as antigen, the specificity of the ELISA was markedly increased since it reached 100% without any decrease of its sensitivity (100%). The serologic follow-up of AE patients was conducted during several months with these two antigens in three categories of patients: cured, stabilized and aggravated. There was a good correlation between clinical and serologic data when the pAP was used as antigen in ELISA tests. The anti-pAP antibodies titres did change more rapidly than anti-EmC antibodies titres when a recurrence occurred. Modifications of the anti-pAP antibodies levels were also observed during the patient's therapy: mebendazole, albendazole and Isoprinosine^®. These results suggest that pAP-Ag should be used for the diagnosis and the follow-up of AE patients.