RNA Metabolism in Normal and Leukaemic Leucocytes: Further Studies on RNA Synthesis

S ummary The Synthesis of RNA * has been investigated in leucocytes isolated from the blood of normal subjects and patients with leukaemia. In addition to ribosomal and soluble RNA, white cells make a rapidly labelled RNA with properties of messenger RNA. RNA synthesis in leukaemic cells is sensitive to pancreatic ribonuclease and actinomycin D, thereby offering evidence in favour of DNA-dependent RNA synthesis in these cells. Leucocytes from some patients with leukaemia manifest a two- to five-fold increase in uridine incorporation into RNA when compared to normal cells. Inhibition of RNA synthesis in leucocytes by alkylating agents administered in vivo or in vitro was observed.     

Antitumour Activity,Toxicity and Disposition of LS 1727, a Nitroso-Chloroethyl Carbamate of 19-Nortestosterone,in Rats and Mice

Abstract: LS 1727, a nitroso-chloroethyl carbamate of 19-nortestosterone, given intraperitoneally had a high cytostatic activity against some experimental tumours. In vitro studies showed that the tested tumours differed in their ability to hydrolyze LS 1727. The hydrolytic capacity was related to the sensitivity to treatment with LS 1727. Distribution studies with double-labelled LS 1727 demonstrated that the chloroethyl-part of the molecule was retained in dimethylbenz(a)anthracene-induced mammary tumours in the rat. Our findings suggest that the antitumour activity of LS 1727 is exerted by alkylating metabolites released at hydrolysis of the compound. LS 1727 had no oral antitumour activity probably due to pre-systemic hydrolysis. When given intravenously, hydrolysis of LS 1727 in lungs caused severe pulmonary toxicity already at low doses.     

Intestinal ascariasis: new plain film features

Radiographs from 30 children with intestinal obstruction caused by a bolus of Ascaris worms were analyzed. Worms could be seen outlined against intestinal gas; the interface between worm bolus and adjacent gas shadows was irregular. Gas trapped within the worm bolus had irregular outlines. There were also fine linear radiolucent shadows and small bubbles. Fluid levels were sometimes distorted by a projecting worm bolus, resulting in a hump effect. Some of the radiolucencies were within the worms. These features were used in an analysis of radiographs from 68 children who did not have bolus obstruction. Of 44 children with proven ascariasis, 28 (64%) had suggestive radiologic features. In four of 24 children without Ascaris ova in the stools, confusion with fecal shadows resulted in a false-positive diagnosis on the radiographs. Recognition of the worm infestation in asymptomatic patients is important because intestinal malabsorption may contribute to nutritional deficiency.     

Sulfhydryl groups in nissl bodies

Summary Structures which contain the major part of the insoluble cytoplasmic sulfhydryl material have been identified with the protein components of the Nissl bodies of neurons. This was done by showing with histochemical techniques the topographical coincidence of reactive sulfhydryl cell regions, and areas selectively stained for nucleic acids. This identification is of considerable interest with respect to nervous tissue, as it was possible to show that the staining for sulfhydryl and nucleic acids in Nissl bodies was increased or decreased as the cells were stimulated or undergoing chromatolysis.     

Partial reductions in mechanical loading yield proportional changes in bone density,bone architecture,and muscle mass

Although the musculoskeletal system is known to be sensitive to changes in its mechanical environment, the relationship between functional adaptation and below‐normal mechanical stimuli is not well defined. We investigated bone and muscle adaptation to a range of reduced loading using the partial weight suspension (PWS) system, in which a two‐point harness is used to offload a tunable amount of body weight while maintaining quadrupedal locomotion. Skeletally mature female C57Bl/6 mice were exposed to partial weight bearing at 20%, 40%, 70%, or 100% of body weight for 21 days. A hindlimb unloaded (HLU) group was included for comparison in addition to age‐matched controls in normal housing. Gait kinematics was measured across the full range of weight bearing, and some minor alterations in gait from PWS were identified. With PWS, bone and muscle changes were generally proportional to the degree of unloading. Specifically, total body and hindlimb bone mineral density, calf muscle mass, trabecular bone volume of the distal femur, and cortical area of the femur midshaft were all linearly related to the degree of unloading. Even a load reduction to 70% of normal weight bearing was associated with significant bone deterioration and muscle atrophy. Weight bearing at 20% did not lead to better bone outcomes than HLU despite less muscle atrophy and presumably greater mechanical stimulus, requiring further investigation. These data confirm that the PWS model is highly effective in applying controllable, reduced, long‐term loading that produces predictable, discrete adaptive changes in muscle and bone of the hindlimb. © 2012 American Society for Bone and Mineral Research © 2013 American Society for Bone and Mineral Research