Stoichiometry of estramustine phosphate binding to MAP2 measured by the disassembly of chick brain MAP2:tubulin microtubules

The concentration of estramustine phosphate required to inhibit the assembly or to induce the disassembly of chick brain MAP2:tubulin microtubules is markedly dependent upon the microtubule protein concentration. Analysis of this relationship shows that estramustine phosphate and tubulin compete for common MAP2 sites, that MAP2 can bind 5-6 moles.mole-1 estramustine phosphate, and that the Kd of these sites is congruent to 20 microM estramustine phosphate. It is proposed that two molecules of estramustine phosphate interact with each of the three tubulin-binding sites of MAP2 and inhibit the MAP2:tubulin interaction by neutralising two highly conserved basic residues.     

A survey of hospital toilet facilities.

OBJECTIVE--To assess the quality of toilet facilities available for disabled people in a large provincial teaching hospital. DESIGN--Survey of toilet facilities for patients on the wards and in the outpatient department. SETTING--Teaching hospital in Leeds. RESULTS--Although the quality of toilet facilities varied, none met the standards recommended by the British Standards Institution. The worst facilities were found on a ward accommodating elderly patients, where the toilets were unsuitable for use by disabled people and bedside commodes had to be used instead. CONCLUSION--Toilet provision within a major hospital failed to meet standards required for disabled people. Admission to hospital may therefore result in loss of independence and dignity. If hospitals are to be centres of excellence, greater consideration must be given to the requirements of disabled people in the design of new wards, and current inadequate facilities should be upgraded.     

Comparison of the amino acid sequences of the transacylase components of branched chain oxoacid dehydrogenase of Pseudomonas putida, and the pyruvate and 2-oxoglutarate dehydrogenases of Escherichia coli

The nucleotide sequence of bkdB, the structural gene for E2b, the transacylase component of branched-chain-oxoacid dehydrogenase of Pseudomonas putida has been determined and translated into its amino acid sequence. The start of bkdB was identified from the N-terminal sequence of E2b isolated from branched-chain-oxoacid dehydrogenase of the closely related species, P. aeruginosa. The reading frame was composed of 65.5% G + C with 82.3% of the codons ending in G or C. There was no intergenic space between bkdA2 and bkdB. No codons requiring minor tRNAs were utilized and the codon bias index indicated a preferential codon usage. The bkdB gene encoded 423 amino acids although the N-terminal methionine was absent from E2b prepared from P. aeruginosa. The relative molecular mass of the encoded protein was 45,134 (45,003 minus methionine) vs 47,000 obtained by SDS/polyacrylamide gel electrophoresis. There was a single lipoyl domain in E2b compared to three lipoyl domains in E2p, and one domain in E2o, the transacylases of pyruvate and 2-oxoglutarate dehydrogenases of Escherichia coli respectively. There was significant similarity between the lipoyl domain of E2b and of E2p and E2o as well as between the E1-E2 binding domains of E2b, E2p and E2o. There was no similarity between the E3 binding domain of E2b to E2p and E2o which may reflect the uniqueness of the E3 component of branched-chain-oxoacid dehydrogenase of P. putida. The conclusions drawn from these comparisons are that the transacylases of prokaryotic pyruvate, 2-oxoglutarate and branched-chain-oxoacid dehydrogenases descended from a common ancestral protein probably at about the same time.     

Effect of urethan anesthesia on cigarette smoke-induced airway injury in guinea pigs

The effect of urethan anesthesia on cigarette smoke-induced airway responsiveness and permeability was studied in the guinea pig. Airway responsiveness was determined by measuring changes to airway resistance to graded doses of aerosolized histamine, and mucosal permeability was determined by measuring the appearance of fluorescein isothiocyanate-dextran (FITC-D) in the blood and examining its distribution in lung tissue after it had been delivered to the lung in an aerosol. The results confirm previous studies that smoke exposure increased airway responsiveness and mucosal permeability. They also show that urethan anesthesia administered before smoke exposure prevented the smoke-related changes in airway reactivity and mucosal permeability. In animals that remained conscious during the smoke exposure, there was increased deposition of the dextran in the regions of the bronchioloalveolar junctions with a more rapid uptake of FITC-D into the blood. We postulate that, when urethan anesthesia is administered before smoke exposure, the exudative phase of the inflammatory reaction produced by smoke exposure is suppressed.     

Structure and function in the excretory systems of some terrestrial prosobranch snails (Cyclophoridae)

The excretory systems of terrestrial prosobranch snails of the family Cyclophoridae, collected in Jamaica, Costa Rica and South Africa, have been examined physiologically and as regards their gross and fine structure. The process of urine formation commences in the heart, where fluid is filtered across the wall of the ventricle. Filtration through the auricular wall is believed to be negligible. The kidney, which contains three types of cell, modifies the composition of the filtrate. One type of resorptive cell, characterized by basal infoldings associated with mitochondria, takes up salts. Another type, with basal subcellular spaces, may be responsible for taking up water. The third type of cell is secretory, producing concretions of uric acid and phospholipid which are liberated into the kidney lumen when the cell degenerates.
The rate and mechanism of urine production have been investigated using injections of inulin. The filtration rate at 25°C is 0.5 μl/g/min, and in 100% R.H. the average rate of urine production is 0–39 μl/g/min.
An accessory excretory organ has been developed from the hypobranchial gland of aquatic forms. It is composed of groups of subepithelial tubular glands opening into the mantle cavity by one or a series of pores, and secreting purines, phospholipids and mucus. There is evidence that this organ becomes progressively more complex in forms occupying drier habitats.
The systems of excretion and osmoregulation in the Cyclophoridae are considered to be very similar to those in their aquatic relatives, the Viviparidae and Ampullariidae. Certainly the cyclophorids are not as well adapted to a terrestrial life as are the Pulmonata, and in many respects they may be considered "aquatic" snails living on land.