Wound complications after median sternotomy: A study of 61 patients from a consecutive series of 9,279

Among a consecutive series of 9,279 sternotomies performed during a period of 2(1/2) years, 61 (0.66%) patients developed significant wound complications. Of these, 58 (95.1%) survived. Sternal infection occurred in 36 patients (0.39%). Predisposing factors included chronic obstructive pulmonary disease, diabetes mellitus, obesity, closed chest massage, prolonged assisted ventilation, and excessive bleeding after operation. Positive end expiratory pressure (PEEP) did not, in itself, predispose to sternal dehiscence. Intermittent positive pressure breathing (IPPB) treatments caused excessive coughing, which may have increased the likelihood of dehiscence. Disposable drapes and expeditious surgery probably contributed to the low incidence of wound infection. Early diagnosis, surgical debridement, rewiring and primary closure with substernal drainage, without continuous antibiotic irrigation, resulted in satisfactory resolution in most patients.     

Investigation of the pH dependence of proton uptake by porcine heart mitochondrial malate dehydrogenase upon binding of NADH

The pH dependence of proton uptake upon binding of NADH to porcine heart mitochondrial malate dehydrogenase (l-malate: NAD⁺ oxidoreductase, EC 1.1.1.37) has been investigated. The enzyme has been shown to exhibit a pH-dependent uptake of protons upon binding NADH at pH values from 6.0 to 8.5. Enzyme in which one histidine residue has been modified per subunit by the reagent iodoacetamide (E. M. Gregory, M. S. Rohrbach, and J. H. Harrison, 1971, Biochim. Biophys. Acta253, 489–497) was used to establish that this specific histidine residue was responsible for the uptake of a proton upon binding of NADH to the native enzyme. It has also been established that while there is no enhancement of the nucleotide fluorescence upon addition of NADH to the iodoacetamide-modified enzyme, NADH is nevertheless binding to the modified enzyme with the same stoichiometry as with native enzyme. The data are discussed in relation to the involvement of the essential histidine residue in the catalytic mechanism of “histidine dehydrogenases” recently proposed by Lodola et al. (A. Lodola, D. M. Parker, R. Jeck, and J. J. Holbrook, 1978, Biochem. J.173, 597–605) and the catalytic mechanism of “malate dehydrogenases” recently proposed by L. H. Bernstein and J. Everse (1978, J. Biol. Chem.253, 8702–8707).     

Separation of haemopoietic cells for biochemical investigation. Preparation of erythroid and myeloid cells from human and laboratory-animal bone marrow and the separation of erythroblasts according to their state of maturation.

The separation of haemopoietic bone-marrow cells by centrifugation through discontinuous density gradients of Percoll is described. This method was used to prepare fractions enriched in erythroblasts, myeloid blast cells or reticulocytes from bone marrow of anaemic and non-anaemic rabbits, from the marrow of other anaemic laboratory animals and from human samples. It is a simple, rapid, reproducible and inexpensive technique that can be readily adapted to suit individual requirements. Secondly, a convenient method is presented for the separation of large quantities of bone-marrow cells into fractions enriched in erythroblasts at different stages of maturation, by velocity sedimentation through a linear gradient of 1-2% sucrose at unit gravity. In vitro, erythroblasts adhere together strongly via a mechanism almost certainly involving a beta-galactoside-specific surface lectin termed erythroid developmental agglutinin. Since the efficiency of cell-separation techniques depends heavily on the maintenance of a single cell suspension in which each unit can move independently, the presence of an adhesive molecule at the cell surface is of considerable significance. The effect of washing the marrow with a lactose-containing medium, which has been shown to remove the agglutinin, was therefore investigated in relation to both methods. The separation on Percoll gradients is considerably enhanced by this treatment. In addition, the unit-gravity sedimentation gradient can be loaded with 5-10 times more cells after lactose extraction in comparison with intact marrow. Although enrichment is less, a useful fractionation according to maturation is still obtained.     

Dehydrogenation by gluconate 6-phosphate dehydrogenase of an isosteric phosphonate substrate analogue.

6,7-Dideoxy-D-gluco-heptonic-7-phosphonic acid, the isosteric phosphonate analogue of gluconate 6-phosphate, was prepared by incubation of the corresponding analogue of glucose 6-phosphate with glucose 6-phosphate dehydrogenase and NADP+ in the presence of an enzyme NADPH-NADP+ recycling system. The analogue of gluconate 6-phosphate is a substrate for yeast gluconate 6-phosphate dehydrogenase, showing Michaelis-Menten kinetics at pH 7.5 and 8.0. At both pH values the Km values are approx. 3-fold higher and the Vmax. values approx. 7-fold lower than those of the natural substrate.     

FLUCTUATIONS IN FREE AMINO ACID POOLS OF GYMNODINIUM SIMPLEX (DINOPHYCEAE) IN RESPONSE TO AMMONIA PERTURBATION: EVIDENCE FOR GLUTAMINE SYNTHETASE PATHWAY1,2

An ammonia limited chemostat culture of Gymnodinium simplex (Lohm.) Kofoid & Swezy was perturbed with ammonia and fluctuations in the free intracellular amino acid pools were followed 80 min. The steady-state value of glutamate was 2.07 ± 10^-15 mol cell^-1 and of glutamine was 0.31 ± 10^-15 mol cell^-1. Five minutes after the perturbation, a substantial rise in glutamine was observed with a corresponding decrease in glutamate. This is considered a result of glutamine synthetase acting as the primary ammonia assimilating enzyme. The level of ammonia and the major free amino acids reached a maximum 10 min after the perturbation and then slowly decreased.     

Environmental and Seasonal Factors Affecting the Frost-induced Stage of Cold Acclimation in Cornus stolonifera Michx

Stem tissues of red-osier dogwood (Cornus stolonifera Michx.) acclimated from −3 C to −40 or −50 C in 8 to 10 weeks under a short photoperiod (9 hours) and controlled temperature conditions. During the summer months plants did not acclimate as well as at other times. The sequence of day/night temperature regimes which induced maximum acclimation was 20/15 C for 5 to 6 weeks; 15/5 C for 2 to 3 weeks; 15/5 C plus 1 hour of frost per day for 1 week. The duration of exposure to each temperature regime influenced the rate and intensity of frost-induced acclimation. Less than 5 weeks of warm temperature preconditioning at 20/15 C reduced subsequent frost-induced acclimation. The inductive influence of frost on cold acclimation was additive over 5 days of repeated exposure, but its effects after the first exposure(s) were not immediate—requiring 1 to 4 days of 15/5 C following the frost treatments for the expression of the frost-induced acclimation to be manifest. There was a 75% increase in rRNA following 3 days of frost exposure and plants in an O₂-free atmosphere during frost exposure failed to acclimate. The results suggest that seasonal acclimation behavior was due to endogenous rhythms rather than developmental stage, and that the frost-induced phase of acclimation involves aerobic metabolic processes.     

Analysis of erythroid differentiation in Friend cells using noninducible variants

A series of Friend cell variants has been isolated by selecting for resistance to different inducers of Friend cell differentiation. This procedure selects for cells which have lost the capacity to differentiate terminally in the presence of inducer. Fluctuation analysis shows that these variants arise during culture and are not induced by the selective conditions. Moreover, mutagenesis of parental cells increases the frequency of occurrence of DMSO-resistant variants. Our evidence suggests that these resistant variants arise by two mechanisms. Some arise spontaneously at a relatively high rate (5 × 10^?5?5 × 10^?6 per cell per generation), but their phenotypes are not necessarily stable on removal of the selective conditions. Stable variants arise spontaneously at a lower frequency which is consistent with a true mutational origin.Screening of these stable resistant variants shows that they have different phenotypes. Some fail to respond to any inducer; others respond to all inducers tested except the one used for selection, whereas others respond to some but not all inducers. Most of the DMSO-resistant variants are noninducible by DMSO for all aspects of Friend cell differentiation tested (that is, globin mRNA, hemoglobin, spectrin and the ability to undergo terminal differentiation). Two variants, however, are inducible for an early marker of differentiation, the erythrocyte membrane protein spectrin, but not for other markers such as hemoglobin, globin RNA or terminal differentiation. This implies that the regulation of the globin pathway can be uncoupled from that of spectrin.     

Studies on the adenosine 3′,5′-monophosphate-dependent protein kinase of Blastocladiella emersonii

Using a combination of Chromatographic and sucrose density gradient techniques under carefully controlled conditions of pH and protease inhibitors, we demonstrate that there is only one form of adenosine 3′,5′-monophosphate-dependent protein kinase in the cytosol fraction of the Blastocladiella emersonii zoospore. If any of these conditions are omitted during extract preparation, one obtains what are apparently multiple forms of the enzyme, which are in reality artifacts due to extensive endogenous proteolytic activity. This endogenous protease is stimulated by alkaline pH and inhibited by antipain. The zoospore protein kinase is similar to type II protein kinase from mammalian cells in several aspects including Chromatographic behavior on DEAE-cellulose column, conditions for subunit dissociation and reassociation, as well as the molecular weight value of the regulatory subunit.