Isolation and growth of a Pseudomonas species that utilizes cyanide as a source of nitrogen

A simple method of isolating bacteria that utilize cyanide as a source of nitrogen for growth has been developed. This involved supplying hydrogen cyanide as a vapour to glucose-containing minimal-salts agar plates. The bacteria isolated were Gram-negative, oxidase-positive rods producing a fluorescent green pigment and were tentatively identified as strains of Pseudomonas fluorescens. Three organisms were studied further and shown to be P. fluorescens biotype II. One of these (NCIB 11764) was grown in a glucose-containing fed-batch culture with either NH4Cl or KCN as the limiting nutrient. Cyanide-grown bacteria produced stoichiometric amounts of ammonia from cyanide when pulsed with cyanide under aerobic conditions. Stimulation of oxygen uptake was seen on addition of cyanide to suspensions of cyanide-grown but not ammonia-grown bacteria.     

Resistance of Some Vitis Rootstocks to Xiphinema index

Thirty-eight grapevine (Vitis spp.) rootstocks were screened in pots for resistance to the dagger nematode, Xiphinema index, from 1979 to 1981. Resistance ratings were based on visible root symptoms and on changes in the nematode populations over 16 months. Nineteen of the 23 Californian hybrid rootstocks tested were resistant, as were ''Harmony'','' ''Freedom,'' ''Schwarzmann,'' and ''3309.'' Two hybrids of V. rufotomentosa, ''171-52'' and ''176-9,'' were possibly immune to X. index. The rootstocks ''ARG 1,'' '' 110 R,'' ''1202,'' and ''1616,'' which are used commercially for phylloxera resistance were susceptible.     

Interferon-gamma induces enhanced expression of Ia and H-2 antigens on B lymphoid, macrophage, and myeloid cell lines

The levels of class II major histocompatibility complex (MHC) antigens (la antigens) on cells of a cultured B lymphoma line (WEHI-279) were significantly increased after 24 hr incubation with medium conditioned by concanavalin A-stimulated mouse or rat spleen cells, or by an azobenzenearsonate- (ABA) specific T cell clone that had been stimulated with ABA-coupled spleen cells or concanavalin A. The levels and properties of the la-inducing activity correlated with those of interferon-gamma (IFN-gamma) measured by inhibition of virus plaque formation. Both the la-inducing activity and the IFN-gamma from the T cell clone had an apparent m.w. of 40,000 determined by gel filtration, were sensitive to treatment with trypsin or exposure to pH 2, but were stable to heat (56 degrees C, 1 hr). The induction of la antigens on WEHI-279 cells was dose-dependent, and the maximum response occurred at a concentration corresponding to 1 to 2 U/ml of antiviral activity. This T cell-derived IFN-gamma-like molecule also increased the expression of cell surface la antigens on another B cell line (WEHI-231), and cell lines of macrophage (J774) and myeloid (WEHI-3B and WEHI-265) origin. Furthermore, in all cases the levels of class I MHC (H-2K or H-2D) antigens were also increased. Similar patterns of induction of Ia and H-2 antigens were obtained with supernatants containing IFN-gamma produced by a monkey cell line (COS) that had been transfected with a plasmid bearing the cloned murine IFN-gamma gene. This activity was sensitive to pH 2 and was not present in the supernatant from COS cells that were not transfected with the murine IFN-gamma gene. These results established that IFN-gamma is the T cell-derived molecule that induces the enhanced expression of Ia and H-2 antigens on B cells and macrophages. A major physiologic role of IFN-gamma may be to regulate immune function through the enhanced expression of MHC antigens.     

Evaluation of bone cement failure criteria with applications to the acetabular region

A Strain energy density (SED) criterion based on a fracture mechanics approach was used to assess the possible failure of acetabular bone cement after total hip replacement. Stress distributions in the cement at the bone-cement interface were calculated using two-dimensional finite element analyses. The results indicate that increasing the thickness of bone cement reduces the risk of cement fracture. The addition of a metal backing to the polyethylene cup and retention of the subchondral bone further reduces the risk of failure. The SED criterion was found to predict the same critical regions as zones of possible cement failure as the von Mises' criterion. Although either criterion can be used for predicting failure in this acetabular analysis both criteria are excessively conservative in predicting failure in regions where high principal compressive stresses are present. Further development of cement failure criteria are indicated.     

Thiolated nucleotides in yeast transfer RNA

By culturing Saccharomyces cerevisiae in growth medium containing Mg³⁵SO₄, we have determined the extent and variation of tRNA thiolation in this yeast. We find that 5-methoxycarbonylmethyl-2-thiouridine (mcm⁵s²U)¹ is the major, if not only, thiolated derivative in S. cerevisiae tRNA. In addition, a comparison of the chromatographic mobility of mcm⁵s²Up on cellulose thin layers with those reported for unknown uridine derivatives found in purified yeast tRNA digests, leads to the conclusion that at least two of these tRNAs contain this modification.     

Discrimination of human placental alkaline phosphatase allelic variants by monoclonal antibodies.

Eighteen monoclonal antibodies were produced by the mouse hybridoma method using purified placental alkaline phosphatase (ALP) as antigen. The ability of the various antibodies to discriminate among allelic variants of the enzyme was tested using a large panel of placental ALPs that had been typed electrophoretically. The panel included sets of samples of each of the six common polymorphic phenotypes as well as a series of rare variants. The reactivity of each antibody with each placental ALP (binding ratio) was determined relative to a single standard placental ALP (type 1) in a quantitative binding assay. The findings for six of the antibodies have already been reported. The results on the other 12 antibodies are presented here, and the combined data on the total series of 18 antibodies are analyzed and discussed. Six of the 18 antibodies showed significantly reduced binding to one or another of the products of the three common alleles. In three cases, the discrimination was reflected by essentially "all-or-none" binding reactions. In the other three cases, the binding differences were less marked but could be demonstrated by quantitative comparisons of the binding ratios. Quantitative binding ratio comparisons also enabled heterozygotes to be differentiated from homozygotes in each case. Some of the antibodies showed reduced binding with certain of the rare variant ALP electrophoretic phenotypes. It is estimated that at a minimum this unselected series of 18 antibodies is directed to at least nine different antigenic determinants on the surface of the placental ALP molecule. The results illustrate the power of monoclonal antibodies to discriminate among allelic variants of enzymes.     

Interaction of F1-ATPase, from ox heart mitochondria with its naturally occurring inhibitor protein. Studies using radio-iodinated inhibitor protein

The ox heart mitochondrial inhibitor protein may be iodinated with up to 0.8 mol 125I per mol inhibitor with no loss of inhibitory activity, with no change in binding affinity to submitochondrial particles, and without alteration in the response of membrane-bound inhibitor to energisation. Tryptic peptide maps reveal a single labelled peptide, consistent with modification of the single tyrosine residue of the protein. A single type of high-affinity binding site (Kd=96 . 10 (-9)M) for the inhibitor protein has been measured in submitochondrial particles. The concentration of this site is proportional to the amount of membrane-bound F1, and there appears to be one such site per F1 molecule. The ATp hydrolytic activity of submitochondrial particles is inversely proportional to the occupancy of the high-affinity binding site for the inhibitor protein. No evidence is found for a non-inhibitory binding site on the membrane or on other mitochondrial proteins. In intact mitochondria from bovine heart, the inhibitor protein is present in an approx. 1:1 ratio with F1. Submitochondrial particles prepared by sonication of these mitochondria with MgATP contain about 0.75 mol inhibitor protein per mol F1, and show about 25% of the ATPase activity of inhibitor-free submitochondrial particles. Additional inhibitor protein can be bound to these particles to a level of 0.2 mol/mol F1, with consequent loss of ATPase activity. If MgATP is omitted from the medium, or inhibitors of ATP hydrolysis are present, the rate of combination between F1 and its inhibitor protein is very much reduced. The equilibrium level of binding is, however, unaltered. These results suggest the presence of a single, high-affinity, inhibitory binding site for inhibitor protein on membrane-bound F1. The energisation of coupled submitochondrial particles by succinate oxidation or by ATP hydrolysis results in both the dissociation of inhibitor protein into solution, and the activation of ATP hydrolysis. At least 80% of the membrane-bound F1-inhibitor complex responds to this energisation by participating in a new equilibrium between bound and free inhibitor protein. This finding suggests that a delocalised energy pool is important in promoting inhibitor protein release from F1. Dissipation of the electrochemical gradient by uncouplers, or the binding of oligomycin or efrapetin effectively blocks energised release of the inhibitor protein. Conversely, the addition of aurovertin or adenosine 5'--[beta, lambda--imido]triphosphate enhances energy-driven release. The mode of action of various inhibitors on binding and energised release of the protein inhibitor is discussed.     

Structural changes of isolated hepatocytes during treatment with digitonin

The structural changes accompanying digitonin-induced release of enzymes and metabolites from isolated hepatocytes have been studied by scanning and transmission electron microscopy. In the initial phase, characterized by total release of the cytosolic marker enzyme, lactate dehydrogenase, the plasma membrane was immediately damaged, rapidly followed by extensive damage to the endoplasmic reticulum. The shape of the cell, however, was maintained, and the mitochondria and nucleus remained tightly held together by the cytoskeleton. Mitochondria remained intact initially, whereas the cytosol became less electron dense and the nuclear chromatin was more dispersed. An intermediate phase was characterized by total release of adenylate kinase and most of the glucose-6-phosphatase, marker enzymes for the mitochondrial intermembrane space and the endoplasmic reticulum, respectively. The outer mitochondrial membrane was ruptured, but mitochondria maintained their normal matrix electron density. In the final phase, characterized by the beginning of citrate synthase release from the mitochondrial matrix space, the mitochondria became swollen, and only the nucleus, inner and outer mitochondrial membranes, and the cytoskeleton could be clearly distinguished. Although the plasma membrane could not be readily discerned in electron micrographs after the initial phase, the plasma membrane marker enzyme 5'-nucleotidase remained associated with digitonin-treated hepatocytes. Acetyl-CoA carboxylase was released much more slowly than lactate dehydrogenase, indicating some severe restriction on its release. The release of acetyl-CoA carboxylase closely paralleled the release of glucose-6-phosphatase. The controlled exposure of hepatocytes to digitonin, therefore, leads to the sequential release of soluble, compartmentalized cellular components and some membrane-bound components, but the mitochondrial membrane, cytoskeleton and the nucleoskeleton survive even long-term digitonin treatment.     

Comparison of Beclomethasone Dipropionate Aerosol and Prednisolone in Reversible Airways Obstruction

This paper describes a double-bond crossover trial of prednisolone and beclomethasone dipropionate aerosol in 38 steroid-dependent patients with reversible diffuse airways obstruction. Altogether there was no difference in the patient''s preference of the two treatment groups or in the number of times they used their bronchodilator aerosol, or in the forced expiratory volume in one second, vital capacity, or peak expiratory flow rate in the two treatment groups. The plasma cortisol levels when the patients were on the aerosol were much higher than when they were on prednisolone. The use of inhaled aerosol steroids seems to be preferable as it eliminates the usual complications of oral steroid therapy.     

Total Hip Replacement in Osteoarthrosis using the Charnley Prosthesis

Charnley low-friction arthroplasty was performed on 352 osteoarthritic hips, usually because of severe pain. Three hundred and twenty hips were reviewed at a special follow-up clinic or by postal questionnaire. After operation 89% of hips were pain-free or caused only occasional discomfort, and in 76% there was an increased range of movement. Of those patients actually seen for review 79% were judged to have a good or excellent result. The most frequent single complication was deep infection, which occurred in 5·3% of hips.