Clinical and Serological Response after Experimental Inoculation with Babesia Divergens of Newborn Calves with and without Maternal Antibodies

The influence of maternal antibodies on clinical and serological response after experimental inoculation with Babesia divergens of newborn calves was studied. Five calves, born to dams seropositive for B.divergens, (Group 1) had specific maternal antibodies when tested 12 h after their first feeding of colostrum. At that point they were inoculated i.v. with B.divergens infected erythrocytes. Five other calves, born to dams seronegative for B.divergens, (Group 2) had no Babesia specific maternal antibodies when inoculated at the same age. Babesia divergens organisms were demonstrated in blood smears from calves in both groups at some point 5 to 10 days p.i. All calves in both groups had B.divergens specific IgM antibodies at 7 to 17 days p.i. as shown by a modified IF-test. Specific IgG antibodies, transferred by colostrum, were found in all calves of Group 1 before inoculation of B.divergens. The IgG titre of these animals increased by a doubling dilution step at 11–25 days p.i. Among calves of Group 2 specific IgG antibodies were found at first between day 9 and 15 p.i. Both IgM and IgG antibody titres had to be investigated since demonstrated IgG antibodies can originate both from maternally transferred antibodies and from actively produced antibodies after an infection. There was no difference in clinical parameters; parasitaemia, PCV, Hb, and rectal temperature between the groups. This experiment gives evidence that there can be a resistance to bovine babesiosis in newborn calves independent of maternal antibodies.     

Effect of rhodium (III) complex on experimental carcinogenesis in the livers of rats treated with thioacetamide

Enzyme activities and protein content were determined in the cytosolic and mitochondrial fractions of liver homogenates obtained from Rh(III) complex-, thioacetamide- and thioacetamide + Rh(III) complex-treated rats. The Rh(III) complex administered to nonthioacetamide-treated rats produced no significant changes either in the enzymatic activities assayed or in the protein concentration. The Rh(III) complex administered to thioacetamide-treated rats produced significant restoration of the following altered values: cytosolic and mitochondrial aspartate aminotransferase, glutamate dehydrogenase, NADP-isocitrate dehydrogenase, and protein concentration. However, a further increase was produced in the activities of glucose-6-phosphate dehydrogenase and malic enzyme. These increases can be interpreted in terms of an enhancement of the NADPH-dependent detoxifying processes and of nucleic acid synthesis and repair.     

High-performance liquid chromatography of uroporphyrinogen and coproporphyrinogen isomers with amperometric detection.

A reversed-phase h.p.l.c. system, with an ODS-Hypersil column with acetonitrile or methanol in ammonium acetate buffer as mobile phase, is described for the separation of uro-and copro-porphyrinogen isomers. The porphyrinogens are detected amperometrically with sensitivity comparable with that of the fluorescent detection of porphyrins. The effects of pH, buffer concentration and organic modifiers on retention and resolution were studied. The method is suitable for both analytical and preparative separation of porphyrinogens.     

ATP-dependence of 125I-insulin binding by rat soleus muscle

Muscle ATP levels were lowered by incubating rat soleus muscles under anaerobic conditions, or in the presence of 2:4-dinitrophenol (0.5 mM), EDTA (5 mM) or mannitol (400 mM). 125I-insulin binding, measured under equilibrium conditions at 25 degrees C, was reduced by 49-71% in ATP-depleted muscles. Insulin binding was also determined using two other procedures which minimized internalization of 125I-insulin: these were (a) 5 min at 25 degrees C, and (b) 24 h at 3 degrees C. Under these conditions, 125I-insulin binding was reduced by 28-55% in ATP-depleted muscles. These results confirm that in soleus muscle the effect of ATP-depletion on 125I-insulin binding is actually concerned with the binding step itself and not merely a reflection of ATP-dependent internalization of the bound hormone.     

Monoclonal antibody to human 66,000 molecular weight plasminogen activator from melanoma cells. Specific enzyme inhibition and one-step affinity purification

Hybridomas producing a monoclonal IgG1 antibody to a human plasminogen-activating enzyme with an apparent mol. wt. of 66,000 (66 K, HPA66) from human melanoma cells were obtained by fusion of NSI-Ag 4/1 mouse myeloma cells with spleen cells from a mouse immunized with a partially purified preparation of the enzyme. Screening for clones of hybridomas producing antibodies to HPA66 was performed with the impure enzyme preparation. A preliminary screening included enzyme-linked immunosorbent assay and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting; the final identification was based on inhibition of the enzymatic activity of HPA66 which was complete at high antibody concentrations. No inhibition of three other human and murine plasminogen activators or of plasmin was observed. Employing a one-step affinity procedure with the antibody coupled to Sepharose, HPA66 was purified approximately 200-fold from conditioned medium from the melanoma cells with a yield of 79%. The purified HPA66 was homogeneous as evaluated by SDS-PAGE. Electrophoresis under reducing conditions indicated that it consisted of one polypeptide chain. The binding constant between the antibody and 125I-labelled HPA66 was approximately 2.5 x 10(9) l/mol. The antibody did not bind to a variety of other plasminogen activators, including 52-K and 36-K human enzymes and 48-K and 75-K murine enzymes. Previously, a monoclonal antibody against another enzyme was derived by the sole use of enzyme inhibition for screening. The present study represents a modification of this procedure that can be used when antibody-unrelated inhibitors of the enzyme are present in hybridoma culture fluid.     

High-performance liquid chromatography of coproporphyrin isomers.

A reversed-phase system is described for the simultaneous isocratic separation of coproporphyrin I, II, III and IV isomers. The retention behaviour of coproporphyrin I and III is studied in detail. The method is suitable for both analytical and semi-preparative separation.     

The in vitro synthesis and characteristics of ribosomal RNA in imaginal discs of Drosophila melanogaster

Summary Late third instar imaginal discs of Drosophila melanogaster cultured in vitro in Robb's tissue culture medium synthesize 38S, 28S and 18S ribosomal RNAs which are qualitatively indistinguishable from their in vivo synthesized counterparts (Fig. 1). As found in other insect systems, the 38S molecule appears to be the precursor for both the 28S and 18S rRNAs (Figs. 2, 3 and 4). The 28S rRNA and a portion of the 38S pre-rRNA shift in sedimentation value upon exposure to heat or dimethylsulfoxide (Figs. 5 and 8). Studies of the thermal denaturations of these molecules (Figs. 6, 7 and 9) indicate the existence of a single class of 28S rRNA, but three classes of 38S pre-rRNAs. The addition of -ecdysone to the in vitro culture medium stimulates the net amount of rRNA synthesized, increases the rate of processing of the 38S precursor and increases the relative amount of 18S material produced (Figs. 10 and 12).This work was supported in part by grants from the National Science Foundation (GB-8176) and from the Atomic Energy Commission (AT-04-3-34).Predoctoral Trainees, PHS Training Grant No. 2-Tl-GM367 from Research Training Grants Branch, National Institute of General Medical Sciences.1 For purposes of simplification we shall refer to the rRNA molecules of D. melanogaster as being 38S, 30S, 28S and 18S; however, it should be noted that these values are approximate (see Hastings and Kirby, 1966; Greenberg, 1969; Tartof and Perry, 1970).