Auxin binding site in tobacco cells

A specific, high affinity, IAA binding site was demonstrated in both a cytosolic fraction, and in isolated nuclei, fromNicotiana tabacum cv. Wisconsin No. 38 cells grown in suspension culture. The amount of the binding site detected in both these fractions changed during the culture cycle according to a strict pattern. The molecular mass of the binding site was estimated by gel filtration to be approximately 175 000 and it appears to be a protein. When partially purified by affinity chromatography and allowed to pre-incubate with IAA, the site had a significant stimulatory effect on total RNA synthesis, as measured by a cell-free assay system. Unpurified extracts had no such effects. The system behaves rather like the steroid hormone-receptor system in animals.     

Automated analysis of three-dimensional stress echocardiography

Real-time three-dimensional (3D) ultrasound imaging has been proposed as an alternative for two-dimensional stress echocardiography for assessing myocardial dysfunction and underlying coronary artery disease. Analysis of 3D stress echocardiography is no simple task and requires considerable expertise. In this paper, we propose methods for automated analysis, which may provide a more objective and accurate diagnosis. Expert knowledge is incorporated via statistical modelling of patient data. Methods for identifying anatomical views, detecting endocardial borders, and classification of wall motion are described and shown to provide favourable results. We also present software developed especially for analysis of 3D stress echocardiography in clinical practice. Interobserver agreement in wall motion scoring is better using the dedicated software (96%) than commercially available software not dedicated for this purpose (79%). The developed tools may provide useful quantitative and objective parameters to assist the clinical expert in the diagnosis of left ventricular function.     

Sex Differences in the Association of Thigh Fat and Metabolic Risk in Older Adults

We have previously shown a favorable association of subcutaneous leg fat with markers of insulin resistance and dyslipidemia in postmenopausal women. It is not known whether there is a sex dimorphism in the association of lower‐body adiposity with reduced metabolic risk. Thus, our primary aim was to determine whether the favorable association of thigh subcutaneous fat, independent of abdominal fat, is also observed in older men. Mid‐thigh and abdominal fat areas were measured by computed tomography (CT) in 108 older men and postmenopausal women (mean ± s.d.; 69 ± 7 years). Additionally, trunk and leg fat mass (FM) were measured by dual‐energy X‐ray absorptiometry (DXA). Markers of insulin resistance and dyslipidemia were determined from oral glucose tolerance tests and lipid and lipoprotein measurements, respectively. Outcomes were fasted and postchallenge (area under the curve, AUC) insulin (INS_AUC) and glucose (GLU_AUC), product of the insulin and glucose AUC (INS_AUC × GLU_AUC), triglycerides (TG), and high‐density lipoprotein (HDL)‐cholesterol. Consistent with our previous findings in postmenopausal women, adjusting for DXA trunk FM revealed a favorable association of DXA leg FM with the metabolic risk outcomes in both older men and postmenopausal women. Likewise, adjusting for CT abdominal visceral fat generally revealed a favorable association of CT thigh fat with metabolic risk outcomes in women, but not men. The discordance between the DXA and CT results in men is unclear but may be due to sex differences in visceral fat accrual. The mechanisms underlying the protective effect of thigh fat on metabolic risk factors need to be elucidated.     

Immunocytochemical localization of the elongation factor Tu in E. coli cells

The localization of the elongation factor Tu (EF-Tu) in ultrathin cryosections of E. coli cells was determined with the electron microscope using a highly specific immunological labelling technique. EF-Tu is distributed almost homogeneously throughout the cytoplasm. Although it has often been suggested that EF-Tu could be part of a putative prokaryotic cytoskeleton, we did not find any evidence for supramolecular assemblies, such as fibres or filaments, containing a large amount of EF-Tu. EF-Tu was not observed in association with the outer cell membrane and periplasmic space. A topological relationship with the inner membrane is not apparent in our micrographs. In cells in which the EF-Tu level is raised significantly, the protein piles up in discrete cell regions.     

Peripheral nerve conduction in the fruit bat with nitrous oxide induced vitamin b12 deficiency

Fruit bats Rousettus aegyptiacus were depleted of vitamin B12 by exposure to the gas nitrous oxide (N2O-oxygen, 1:1 v/v) for 57-80 days. Conduction velocities along the fastest fibres of the ulnar nerve, as well as the first and second peaks, were similar in control and vitamin b12 depleted animals. It is concluded that neurological impairment resulting from depletion of vitamin B12 by N2O does not involve significant impairment of ulnar nerve function in this species.     

Catalytic hydrogenation of fatty acyl chains in plasma membranes; effect on membrane lipid fluidity and expression of cell surface antigens

Optimal reaction conditions were established for hydrogenation of plasma membranes of living murine GRSL leukemia cells, using the water-soluble catalyst Pd(QS)2 (QS, sulphonated alizarine; C14H6O7NaS). Under these conditions more than 80% of the cells remained viable. Analysis by gas chromatography revealed that hydrogenation occurred predominantly in the 18:2, 20:4 and 22:6 fatty acyl chains of the membrane phospholipids. Under the same conditions hydrogenation was also performed in purified plasma membranes from GRSL cells and from rat liver, and in liposomes prepared from the total lipid extracts of these membranes. Hydrogenation increased the lipid structural order parameter in the membranes, as measured by fluorescence polarization. This increase was more pronounced in the liposomes (46%) than in the plasma membranes (17-25%). Hydrogenation increased the expression of a 15 kDa antigen on the surface of viable GRSL cells, as measured in a Fluorescence Activated Cell Sorter, using monoclonal antibodies. The expression of four other antigens, among which H-2k, was not or much less affected by this treatment.