The effect ofn-alkanes in the degradation of dibenzothiophene and of organic sulfur compounds in heavy oil by aPseudomonas sp.

Summary The microbial degradation of organic sulfur compounds was examined in aerobic conditions employing a pure culture of aPseudomonas sp., isolated from the soil. The effect ofn-alkanes on the degradation of dibenzothiophene (DBT) showed that the assimilation of the sulfur compound by the microorganism is favoured byn-dodecane. Moreover, the saturated fraction was seen to enhance the degradation of the sulfur compounds to be found in a deasphaltenated heavy oil.     

Topographical localisation of endothelin mRNA and peptide immunoreactivity in neurones of the human brain

Summary The distribution of endothelin mRNA and immunoreactivity in the human brain was investigated using the technique of in situ hybridization and immunocytochemistry. Cryostat sections from 22 cases of neurologically normal adult human brain, collected 3–7 h post-mortem were hybridized with³⁵S-labelled complementary (c)RNA probes prepared from the 3 non-coding region of endothelin-1 cDNA, and the chromosomal genes encoding endothelin-2 and -3. In situ hybridization with all three cRNA probes revealed labelled neuronal cell bodies in laminae III–VI of the parietal, temporal and frontal cortices. Labelled cells were also seen, scattered throughout the para- and periventricular; supraoptic and lateral hypothalamic nuclei, the caudate nucleus, amygdala, hippocampus, basal nucleus of Meynert, substantia nigra, raphe nuclei, Purkinje cell layer of the cerebellum and in the dorsal motor nuclei of the vagus of the medulla oblongata. The distribution of neurones immunoreactive to endothelin was similar to that of endothelin mRNA, although fewer immunoreactive cells throughout the brain, were noted. Immunoreactive fibres were present mainly in the cortex and hypothalamus, and to a lesser extent in the brain stem. Combined in situ hybridization and immunocytochemistry on the same section revealed the presence of endothelin-1 mRNA and immunoreactivity in the same cortical neuronal cell. Colocalisation studies in the cortex revealed endothelin-1 mRNA and immunoreactivity in a number of cells which also expressed neuropeptide Y mRNA and immunoreactivity. In the hypothalamus and basal nucleus of Meynert endothelin immunoreactivity was colocalised to a subset of neurophysin- and galanin-immunoreactive cell bodies respectively. Endothelin mRNA and immunoreactivity was also seen in some blood vessel endothelial cells. The findings of endothelin mRNAs and immunoreactivity in heterogenous neuronal populations further emphasises the potential role of endothelin as a neuropeptide, probably having diverse actions in the nervous system of man.     

Asymmetric reduction of ketones with resting cells of Sulfolobus solfataricus

The method of resting cells has been of interest in the development of biocatalysts applied to organic reactions.This article deals with the use of resting cells of a thermophilic archaebacterium Sulfolobus solfataricus, in the asymmetric reduction of acyclic, cyclic, and aromatic ketones. The system allows the continuous regeneration of endogenous coenzyme with the coupled substrate approach. The results indicate that the direction of hydride attack was equatorial on the re face of the carbonyl group of substrates producing (S)-alcohols with a good optical yield. A convenient system for the reuse of resting cells has been set out to synthesize (S)-alcohols on a preparative scale.     

Stimulation and priming of protein kinase C translocation by a Ca2+ transient-independent mechanism. Studies in human neutrophils challenged with platelet-activating factor and other receptor agonists

N-Formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4 stimulate human polymorphonuclear neutrophils (PMN) to translocate protein kinase C from the cytosol to plasmalemma as judged by their abilities to increase PMN binding of and receptor numbers for [3H]phorbol dibutyrate [( 3H]PDB) (O'Flaherty, J.T., Jacobson, D.P., Redman, J.F., and Rossi, A.G. (1990) J. Biol. Chem. 265, 9146-9152). Platelet-activating factor (PAF) had these same effects. Moreover, two potent PAF analogs (but not an inactive analog) increased [3H]PDB binding; a PAF antagonist blocked responses to PAF without altering those to fMLP; and PMN treated with PAF became desensitized to PAF while retaining sensitivity to fMLP. Indeed, PMN incubated with 1-100 nM PAF for 5-40 min had markedly enhanced [3H]PDB binding responses to fMLP. PAF thus acted through its receptors to stimulate and prime protein kinase C translocation. Its effects, however, did not necessarily proceed by a standard mechanism: Ca2(+)-depleted PMN failed to raise Fura-2-monitored cytosolic Ca2+ concentrations [( Ca2+]i), yet increased [3H]PDB binding and receptor numbers almost normally after PAF challenge. PAF also primed Ca2(+)-depleted PMN to fMLP. Nevertheless, [3H]PDB binding responses to PAF were blocked in PMN loaded with Ca2+ chelators, viz. Quin 2, Fura-2, or 5,5'-dimethyl-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Exogenous Ca2+ reversed Quin 2 inhibition, and a weak chelator 4,4'-difluoro-BAPTA, lacked inhibitory actions. The chelators similarly influenced fMLP and leukotriene B4. Thus, PMN can by-pass [Ca2+]i to translocate protein kinase C. They may achieve this using a regulatable pool of Ca2+ that evades conventional [Ca2+]i monitors or a signal that needs cell Ca2+ to form and/or act. This signal may mediate function in Ca2(+)-depleted cells, the actions of [Ca2+]i-independent stimuli, cell priming, and protein kinase C movements that otherwise seem [Ca2+]i-induced.     

Effect of chloramphenicol,antimycin A and hydroxamate on the morphogenetic development of the dimorphic ascomyceteEndomycopsis capsularis

Mitochondrial protein synthesis, primary (antimycin-sensitive) respiration and secondary (antimycin-insensitive, salicyl-hydroxamate-sensitive) respiration, have been characterized in the dimorphic yeastEndomycopsis capsularis. The inhibition by chloramphenicol (CAP) of the morphogenetic development from the yeast-like form to the mycelial structure in this yeast could represent the intervention in the morphogenetic process of mitochondrial protein synthesis, since chloramphenicol blocks in vivo and in vitro mitochondrial protein synthesis. In fact, other functions such as primary and secondary respiration, do not seem to play a role in the morphogenetic development since their inhibition by antimycin A (AA) or by salicyl-hydroxamic acid (SHAM) does not affect the process. In addition, mitochondrial protein synthesis has been shown to be uninhibited by the two respiratory inhibitors.     

Haemolytic uraemic syndrome: therapeutic effect of plasma infusion.

The therapeutic effect of plasma infusion was evaluated in 10 children and seven adults with haemolytic uraemic syndrome. All but one patient responded to this treatment with rapid disappearance of haematological abnormalities. The patient who apparently failed to respond to plasma infusion obtained complete remission of the disease after plasmapheresis. Although 15 of the 17 patients were anuric or oliguric on admission, renal function recovered completely in eight children and two adults. Seven patients showed residual chronic renal failure and two required long-term maintenance haemodialysis. Treatment with plasma was also successful in patients with relapses or recurrent episodes. Plasma infusion is a promising therapeutic approach for the haemolytic uraemic syndrome and deserves further study in clinical trials.     

Biosynthesis of 1α,2α,3β-trihydroxy-p-menthane by Fusicoccum amygdali

Measurement of isotope ratios in 1α,2α,3β-trihydroxy-p-menthane, which has been biosynthesized in Fusicoccum amygdali from ³H- and ¹⁴C-labelled mevalonate and in its degradation product diosphenol indicates that: (a) four tritium atoms arising from [5-³H₂, 2-¹⁴C]MVA are retained, one more than suggested from the hydroxylation pattern, (b) menth-2-ene-1-ol is generated from an α-terpinyl cation through a 1,3-hydride shift and (c) trans-cleavage of an α-epoxide by hydrolysis gives 1α,2α,3β-trihydroxy-p-menthane.     

Trypsin activation of the red cell Ca2+-pump ATPase is calcium-sensitive

Stimulation of the calmodulin-independent activity of the red cell Ca2+-pump ATPase by trypsin treatment (of calmodulin free red cell membranes) is sensitive to Ca2+ in a concentration range near the KCa of the transport site. The Ca2+ requirement for this effect is absolute, whereas the calmodulin sensitivity of the ATPase can be abolished by sufficient trypsin attack in the absence of Ca2+, although Ca2+ accelerates inactivation. This indicates that the two effects of trypsin are due to at least two distinct cleavage sites in the pump protein.     

Increased myocardial pyrimidine nucleotide synthesis in isoproterenol-induced cardiac hypertrophy in rats

In a first phase (up to 12^h) after the first injection of isoproterenol (5mg.kg^?1 b.w.) the pyrimidine nucleotide pools were increased and the rates of incorporation of inorganic phosphate into the α-phosphate groups of nucleotides were raised from 16 to 58 nmol.g^?1.h^?1 for uracil nucleotides and from 11 to 32 nmol.g^?1.h^?1 for cytosine nucleotides. At a later stage, while the pool sizes decreased slowly toward control levels, these rates of labelling also decreased though still remaining above control values. A similar pattern of changes was induced by the eighth daily isoproterenol injection, but the alterations were attenuated.