Importance of fatty acid oxidation in the neonatal pig heart with hypoxia and reoxygenation

We investigated mechanical and metabolic responses in isolated, isovolumically-beating, pig hearts (n = 7), 12 h to 2 days of age; subjected to hypoxia followed by reoxygenation. Hearts were perfused with an erythrocyte-enriched (hematocrit approximately 15%) solution during 3 consecutive 30-min periods: pre-hypoxia, arterial perfusate [O2] = 7.6 +/- 0.2 vol% (PO2 approximately 270 torr); hypoxia, [O2] = 0.6 +/- 0.1 vol% (approximately 10% hemoglobin saturation) and reoxygenation. Prehypoxia parameters averaged: left ventricular peak systolic pressure, 107.1 +/- 2.9 mmHg and end-diastolic pressure, 0.9 +/- 0.3 mmHg; coronary flow, 2.8 +/- 0.2 ml/min per g; myocardial O2 consumption, 59.4 +/- 1.6 microliters/min per g and fatty acid oxidation, 37.1 +/ 1.1 nmol/min per g. Fatty acid oxidation was determined using [14C]palmitate. Early in hypoxia, coronary flow increased 3-4 fold but then decreased. Throughout hypoxia, hearts released lactate yet continued to oxidize fatty acids (45-50% of myocardial O2 consumption). By the end of the hypoxia period, hearts exhibited mechanical failure (peak systolic pressure approximately 55 mmHg and end-diastolic pressure approximately 19 mmHg). After 30 min of reoxygenation, peak systolic pressure recovered to 80.6 +/- 2.6 mmHg and end-diastolic pressure remained elevated at 6.1 +/- 1.9 mmHg. However, fatty acid oxidation rates were 90-95% above pre-hypoxia values. Thus, during 30 min of severe hypoxia neonatal pig hearts exhibited mechanical dysfunction, yet continued to oxidize exogenously supplied fatty acids. Moreover, fatty acid oxidation was enhanced during reoxygenation.     

Influence of BA and sucrose on the competence and determination of pepper (Capsicum annuum L. var. Sweet Banana) hypocotyl cultures during shoot formation

Summary The simultaneous presence of 6-benzyladenine (BA) and sucrose in a Murashige and Skoog medium (SIM) during the initial stages of shoot initiation have been found to be obligatory for high-frequency shoot formation in the Capsicum annuum L. var. Sweet Banana upper hypocotyl explants. The explants are determined for shoot formation following a minimum of 8 days of culture on SIM. Deprivation of exogenous sucrose from day 6 to day 20 of culture had no effect on the shoot forming response of the explants. BA and sucrose appear to act independently on different aspects of the competence of explants to respond to SIM during shoot initiation.Abbreviations BA N⁶-benzyladenine - MS Murashige and Skoog medium - SIM shoot induction medium - HFM hormone free medium - SUC sucrose minus medium     

The Total Chemical Synthesis of Monocyte Chemotactic Protein-1 (MCP-1)

The affinity-based N^α-amino protecting group tetrabenzo [a,c,g,i]fluorenyl-17-methoxycarbonyl (Tbfmoc) has been utilized as a hydrophobic probe to allow the simple, quick and highly effective isolation of a 76 residue cysteine-containing protein (MCP-1). The base-labile Tbfmoc group can be removed under very mild conditions, which preserve the thiol-con taining protein in the reduced state. Oxidative folding was then used to furnish the biologically active β-chemokine MCP-1.     

Purification and characterization of large and small subunits of ribulose 1,5-bisphosphate carboxylase expressed separately in Escherichia coli

Procedures were developed for 95 and 80% purification to homogeneity of the large subunit (L) and small subunit (S) of ribulose 1,5-bisphosphate carboxylase/oxygenase (L8S8) from Synechococcus PCC 6301, each expressed separately in Escherichia coli. Purified L had a low specific activity in the absence of S (0.075 mumol CO2 fixed/mg holoenzyme/min). Following elution on a Pharmacia Superose 6 or 12 gel filtration column, 50% of the purified L appeared as the octamer, L8. The rest was in equilibrium with lower polymeric species and/or was retained on the column. Large and small subunits assembled rapidly into the L8S8 holoenzyme that had high specific activities, 6.2 and 3.1 mumol CO2 fixed/mg holoenzyme/min for the homologous Synechococcus L8S8 and the hybrid Synechococcus L-pea S L8S8, respectively. The CO2 dependence for carbamylation of L8 was compared to that of L8S8 as a function of pH and CO2 concentration. The pH dependence indicated an apparent pKa for L8 of 8.28 and for L8S8 of 8.15, suggesting that S may influence the pKa of the lysine involved in carbamylation. The Kact for CO2 at pH 8.4 were similar for L8 (13.5 microM) and L8S8 (15.5 microM). L8 bound 2-[14C]carboxy-D-arabinitol 1,5-bisphosphate (CABP) tightly so that most of the bound [14C]CABP survived gel filtration. A major amount of the L8-[14C]CABP complex appeared as larger polymeric aggregates when eluted in the presence of E. coli protein.     

N-terminal sequence of porcine big gastrin: Sequence, synthesis, and immunochemical studies

The synthesis of fragments corresponding to the N-terminal region of porcine big gastrin is described. Radioimmunoassay using synthetic peptides supports the revised structure for the hormone.     

Development of ETB Selective Agonists: Solution Structure of a Linear Endothelin-1 Analogue,ET-1 [Cys(Acm)1,15, Ala3, Leu7, dAsp8, Aib11]

Abstract

The solution structure of a synthetic ET_B selective agonist, ET-l[Cys(Acm)^1,15, Ala³, Leu⁷, dAsp⁸, Aib¹¹] has been solved by ¹H NMR and molecular modelling studies. Such solution structures of linear modified peptides in aqueous methanol are being used in an ongoing program of research designed to assist in an understanding of the basic structural requirements for the biological activity of vasoconstrictors. The resulting structure of this peptide is characterised by an α-helical conformation between residues Leu⁶-His¹⁶ and by N- and C-termi- ni which assume no defined conformation. A knowledge of the solution structures of this and related peptides, which are ETB selective agonists, are proving to be important in the understanding of how they interact with the ETB receptor.     

Pathogenesis of Fungal Infections in Cystic Fibrosis

For a long time, the microbiology of cystic fibrosis has been focussed on Pseudomonas aeruginosa and associated Gram-negative pathogens. An increasing body of evidence has been compiled demonstrating an important role for moulds and yeasts within this complex patient group. Whether or not fungi are active participants, spectators or transient passersby remain to be elucidated. However, functionally, they do appear to play a contributory role in pathogenesis, albeit we do not know if this is a direct or indirect effect. The following review examines some of the key evidence for the role of fungi in CF pathogenesis.