Isolation of serum chylomicrons prior to density gradient ultracentrifugation of other serum lipoprotein classes

A method for the removal of serum chylomicrons before density gradient ultracentrifugation of the other serum lipoproteins using an SW 41 swinging bucket rotor is presented. In a preliminary spin, the chylomicrons with an Sf greater than 400 X 10(-13) s float to the top of the gradient, whereas the other lipoproteins are retained in the infranatant fraction. After removal of the chylomicrons, the other serum lipoproteins are subsequently fractionated by isopycnic density gradient ultracentrifugation. Analysis of the separated lipoprotein fractions suggested that this procedure permits isolation of a chylomicron fraction consisting solely of chylomicrons but that the very low density lipoprotein fraction subsequently isolated also contains chylomicrons or chylomicron remnants with an Sf less than 400 X 10(-13) s, and that there is considerable overlap in flotation rate and particle size of very low density lipoproteins and chylomicrons.     

Characterization of messenger RNA from epimastigotes and metacyclic trypomastigotes of Trypanosoma cruzi

The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes.     

Vaccination of mice against murine coccidiosis by ingestion of surface proteins of Eimeria falciformis incorporated in liposomes

Proteins are released from the surface of sporozoites of Eimeria falciformis during their in vitro incubation in a detergent solution. Some of these proteins reacted with antibodies from infected mice and specifically stimulated the proliferation of mesenteric lymph node cells of these mice. Oral immunization of mice with liposome encapsulated sporozoite surface antigens protected mice against a challenge infection. Two proteins (M.W. 27 and 180 K) induced an antibody synthesis in these vaccinated mice.     

Growth inhibitory effects of 5-aza-2'-deoxycytidine in HL-60 promyelocytic leukemia cells resistant to differentiation induction

In the original HL-60 cells (HL-60-S) and an HL-60 subline (HL-60-R) respectively susceptible and resistant to induction of differentiation by retinoic acid or dimethyl sulfoxide, 5-aza-2'-deoxycytidine inhibited growth equally but induced differentiation to a greater extent in HL-60-S. Flow cytometry showed that 5-aza-2'-deoxycytidine produced in both HL-60 lines an increased proportion of cells in G2+M rather than G0/G1 as with retinoic acid. 5-aza-2'-deoxycytidine may have a differentiation-inducing effect in HL-60 provided cells have the competence to differentiate, indicating the importance of an alternate mechanism of action.     

Changes in glycosylated haemoglobin after poor control in insulin-dependent diabetics.

Glycosylated haemoglobin (HbA1) was measured in seven insulin-dependent diabetic patients before, during, and after a seven-day period of monitored poor control. There was considerable individual variation in the pattern and degree of change in HbA1 concentration induced by poor control and the time when it occurred. Greater increases in HbA1 were seen during the period of metabolic derangement than in the subsequent two months. More information is required before HbA1 estimations are widely used clinically to monitor control in individual diabetics.     

Diagnostic test systems based on the immunoenzyme method in leprosy

Diagnostic test systems for the detection of IgG and IgM to Mycobacterium leprae in the blood sera of leprosy patients and armadillos experimentally infected with M. leprae have been developed on the basis of the indirect immunoperoxidase assay. The possibility has been shown of prognosing the activity of the leprotic process in leprosy patients and the results of the experimental infection of armadillos by the dynamic increase of antibody reactions with the development of the infection.     

Synthesis of new olean-18(19)-ene derivatives from allobetulin

New olean-18(19)-ene triterpenoids were effectively synthesized by the interaction of allobetulin or its acetate with phosphorous oxychloride in refluxing pyridine. The structures of the synthesized 17-chloromethyloleane-18(19)-enes were confirmed by NMR spectroscopy and X-ray analysis.     

Comparison of optimization methods for fed-batch cultures of hybridoma cells

Two methods for the calculation of optimal trajectories for the input variables of a fed-batch culture of hybridoma cells are compared. It pointed out that a gradient method based on Pontryagins' minimum principle based yields a significant better performance with respect to computational effort and the calculated minimum than a dynamic programming approach which has been presented in a previous paper [1] as the most suitable method.     

Human beta-glucuronidase. Studies on the effects of pH and bile acids in regard to its role in the pathogenesis of cholelithiasis

Human bile contains a considerable amount of endogenous beta-glucuronidase. The effects of pH and bile acids on its activity have been studied in regard to its role in the pathogenesis of cholelithiasis. beta-Glucuronidase, purified from human liver to homogeneity, was structurally stable between pH 4 and 10, but was active only over a much narrower range of pH, with a pH optimum of 5.2. The inactivation below pH 4 was due to its irreversible denaturation, whereas the inactivation at higher pH was due to a true reversible pH effect on the enzyme velocity. Kinetic studies revealed that hydrogen ion acted as a substrate-directed activator of the free enzyme, but not the enzyme-substrate complex, with a molecular dissociation constant of 4 X 10(-6). The enzyme activity was not affected by unconjugated bile acids, primarily due to their extremely low water solubility. Conjugated bile acids, on the other hand, exerted heterogeneous and pH-dependent effects on the enzyme. At pH 5.2, taurocholic acid and glycocholic acid were substrate-directed activators of the enzyme; taurochenodeoxycholic acid and taurodeoxycholic acid, competitive inhibitors; and glycochenodeoxycholic acid and glycodeoxycholic acid, mixed inhibitors. At pH 7.0 all taurine and glycine conjugates behaved as substrate-directed activators. Though beta-glucuronidase activity at pH 7 was only 23% of its maximal activity at pH 5.2, conjugated bile acids tended to restore its activity to a certain extent at pH 7. Thus, endogenous beta-glucuronidase could play a significant role in pigment cholelithiasis.     

In vitro modulation using a synthetic antioxidant of the stimulus-induced formation of cyclic AMP

The in vitro treatment of membranes isolated from different rat organs with a water-soluble synthetic antioxidant has resulted in the change of basal and stimulus-induced adenylate cyclase activity. It is believed that the antioxidant effect is realized rather at the level of signal transfer from activated receptor to adenylate cyclase than at the level of agonist-receptor interaction.