Changes in serum immunoglobulins in subjects with acute myocardial infarct and essential hypertension

20 (12 men and 8 women) acute myocardial infarction (AMI) patients and 17 (14 men and 3 women) patients with arterial hypertension (II degrees stage according to OMS) in comparison to controls age and sex matched, were studied, serum IgA, IgG, IgM were evaluated with radial immunodiffusion and serum IgE with RIA. Ho significant changes ef immunoglobulins were observed between hypertensive patients and controls; whereas a significant increase of IgM, IgG and IgE, with out changes of IgA, were shown in AMI patients. Serum Ig and IgM were significantly augmented in AMI patients in comparison to hypertensive patients.     

Electron paramagnetic resonance and optical spectroscopic study of the Cu2+-tRNA system

The interaction of copper ions with tRNA has been studied by optical and EPR spectroscopies. The interaction results in two different paramagnetic complexes characterized by a tetragonal symmetry of the ligand electric field sensed by the ions. The complete set of the spin Hamiltonian parameters has been extracted by computer simulation with the Monte Carlo method. Hypotheses concerning the putative ligands are put forward.     

The 5' ends of Escherichia coli lac mRNA

We identified the predominant 5' ends of an mRNA in Escherichia coli to the exact nucleotides. There are four such ends of lac mRNA in fully induced cells. About 70% of the molecules have the reported major in vitro end, A-A-U-U-G (at +1), which is located 38 nucleotides before the A-U-G translation start. Another 15% start with A-U-U-G at +2, and about 8% start with A-U-U-A-G at -52. A fourth class of molecules begin with either A-G, C-A-G, A-C-A-G, or a weak A-C-A-C-A-G (at +24), observed only once. The origins of this latter set (less than or equal to 10% of the total) are not known, but they could represent "ragged" ends of the mRNA when it is degraded to the beginning of the ribosome-protected region of the message. The A-U-U-A-G molecules are probably initiated from an upstream promoter whose position would coincide with the cAMP-CRP DNA binding site for the major promoter.     

A spin label ESR and saturation transfer-ESR study of archaebacteria bipolar lipids

A spin label study has been carried out on bipolar lipids extracted from Sulfolobus solfataricus, an extreme thermophilic archaebacterium growing at about 85°C and pH 3. These lipids are cyclic diisopranyl tetraether molecules, quite different from the usual fatty acid lipids. Two hydrolytic fractions of the membrane complex lipids have been studied: the symmetric lipid glycerol-dialkyl-glycerol-tetraether (GDGT) and the asymmetric lipid glyceroldialkyl-nonitol-tetraether (GDNT). The ESR spectra confirm the results previously obtained from calorimetric and X-ray diffraction experiments showing a polymorphic behaviour of these lipids and indicating the critical temperature ranges at which structural transitions occur. Moreover, the present study adds information on the dynamics of the different portions of the hydrophobic chain. ST-ESR measurements show correlation times ranging from 10^-8 s up to 10^-5 s, depending upon the lipid sample, the label position and the degree of hydration. At very high temperatures, i.e. the physiological temperatures of Sulfolobus solfataricus, the nonitol head groups of the asymmetric lipids form a strongly immobilized structure. Indeed, the molecular correlation times of the outermost hydrophobic portion of GDNT are higher, by a factor up to 10³, than those of usual monopolar lipids. Anisotropic motional behaviour is observed even at such very high temperatures. Possible biological implications are discussed.Abbreviations used are ESR electron spin resonance - St-ESR saturation transfer electron spin resonance - GDGT glyceroldialkyl-glycerol-tetracther - GDNT glycerol-dialkyl-nonitoltetraether - 5 SASL 12SASL and 16SASL, stearic acid spin labels, N-oxyl-4,4-dimethyloxazolidine derivatives of 5-ketostearic acid, 12-ketostearic acid and 16-ketostearic acid, respectively - DSC differential scanning calorimetry     

Effects of Somatostatin on Intracellular Calcium Concentration in PC12 Cells

Abstract: Somatostatin (SS) is a neuropeptide that is distributed in various regions of the CNS, where it may act as a neurotransmitter or neuromodulator. SS produces multiple effects in the CNS through interactions with membrane receptors. In particular, SS inhibits various secretory responses in different cell types. In the present study, we have investigated the effects of exogenous application of SS on the intracellular free Ca²⁺ concentration ([Ca²⁺]_i) in PC12 cells, a rat pheochromocytoma cell line. SS did reduce the magnitude of the secondary, maintained Ca²⁺ influx brought about by K⁺ depolarization. Similar effects were obtained with the application of SS analogues, such as d -Trp⁸-SS, d -Trp⁸- d -Cys¹⁴-SS, CGP-23996, and SMS-201995. In addition, treatment with cyclo-SS, a SS antagonist, did not alter [Ca²⁺]_i. Experiments with selective blockers of different voltage-dependent Ca²⁺ channels, such as methoxyverapamil (D600) and Ω-conotoxin GVIA, demonstrated that the effects of SS on [Ca²⁺]_i were mediated by voltage-dependent Ca²⁺ channels of the L type. Control experiments with a membrane potential indicator, i.e., the fluorescent dye bisoxonol, excluded that SS influenced the level of the membrane potential. SS effects on PC12 cells suggest the possibility that this neuropeptide plays a role in the modulation of cell functional activity by altering Ca²⁺ influx.     

Photosensitization by hematoporphyrin: ESP evidence for free radical induction in unsaturated fatty acids and for singlet oxygen production.

Hematoporphyrin ability to photoreact by type I and type II mechanisms was investigated in some model systems. At room temperature, visible irradiation of hematoporphyrin-unsaturated fatty acids and hematoporphyrin-cholesterol systems resulted in the Electron Spin Resonance (ESR) spectrum of the hematoporphyrin free radical. Triplet state hematoporphyrin is shown to be involved in the electron transfer from the lipid moiety. Moreover an ESR method to monitor the singlet oxygen production by hematoporphyrin was used. β-carotene effect on both mechanisms (type I and type II) was tested.     

Subunit structure and kinetic properties of L-beta-hydroxy acid dehydrogenase of Drosophila.

L-beta-hydroxyacid dehydrogeanse (L-gulonate:NAD+ 3-oxidoreductase, EC 1.1.1.45) of Drosophila is made up of two non-identical subunits with molecular weights of 40 000 and 23 500. Michaelis constants calculated at saturating concentrations of the other substrate were 0.13 mM for NAD+, 0.85 mM for L-gulonate, 14.8 mM for L-beta-hydroxybutyrate; dissociation constants (Kia) were 2.8 mM for L-gulonate, 22 mM for L-beta-hydroxybutyrate. The maximum velocity with L-gulonate as substrate was ten-fold greater than with beta-hydroxybutyrate. As product inhibitors, both NADH and acetoacetate are competitive vs. both substrates, suggesting a rapid equilibrium random mechanism.     

Purification of fatty acid ethyl esters by solid-phase extraction and high-performance liquid chromatography

We have developed a two-step method to purify fatty acid ethyl esters (FAEE) using solid-phase extraction (SPE), with a recovery of 70±3% (mean±S.E.M.) as assessed using ethyl oleate as a recovery marker from a standard lipid mixture in hexane. The first step of the SPE procedure involves application of a lipid mixture to an aminopropyl-silica column with simultaneous elution of FAEE and cholesteryl esters from the column with hexane. Gas chromatographic analysis of FAEE without interference from cholesteryl esters may be performed using the eluate from the aminopropyl-silica column, thus eliminating the need for an octadecylsily (ODS) column in this case. The FAEE can then be separated from the cholesteryl esters, if necessary, by chromatography on an ODS column and elution with isopropanol-water (5:1, v/v). Both the aminopropyl-silica and ODS columns were found to be effective for up to four uses. To permit isolation of specific FAEE species following isolation of total FAEE by the two-step SPE method, we have also developed a purification scheme for individaal FAEE by high-performance liquid chromatography (HPLC). Thus, this simple method allows for reproducible isolation of total FAEE by SPE and isolation of individual FAEE species by HPLC.     

Scanning tunneling spectroscopy investigation of self-assembled plastocyanin mutants onto gold substrates under controlled environment

The study of the electronic conduction through plastocyanin (PC) mutants assembled on a gold surface has been addressed by scanning tunneling spectroscopy. The two mutants exploit a single thiol group (PCSH) or a disulfide bridge (PCSS) to covalently bind at gold surface. The I-V measurements were performed by positioning the STM tip on top of a single molecule and sweeping the bias potential between +/-1 V, under both ambient and controlled atmosphere. For PCSS, under ambient conditions, asymmetric I-V characteristics were obtained, which disappear under nitrogen atmosphere. PCSH, instead shows a symmetric I-V relation in air and under nitrogen environment. Here, as factors underlying this distinct electron conductive behaviour, a potential role for hydration water molecules and for copper redox levels are discussed.     

Bacillus subtilis hydrolyzes CheY-P at the location of its action,the flagellar switch

In this report we show that in Bacillus subtilis the flagellar switch, which controls direction of flagellar rotation based on levels of the chemotaxis primary response regulator, CheY-P, also causes hydrolysis of CheY-P to form CheY and Pi. This task is performed in Escherichia coli by CheZ, which interestingly enough is primarily located at the receptors, not at the switch. In particular we have identified the phosphatase as FliY, which resembles E. coli switch protein FliN only in its C-terminal part, while an additional N-terminal domain is homologous to another switch protein FliM and to CheC, a protein found in the archaea and many bacteria but not in E. coli. Previous E. coli studies have localized the CheY-P binding site of the switch to FliM residues 6-15. These residues are almost identical to the residues 6-15 in both B. subtilis FliM and FliY. We were able to show that both of these proteins are capable of binding CheY-P in vitro. Deletion of this binding region in B. subtilis mutant fliM caused the same phenotype as a cheY mutant (clockwise flagellar rotation), whereas deletion of it in fliY caused the opposite. We showed that FliY increases the rate of CheY-P hydrolysis in vitro. Consequently, we imagine that the duration of enhanced CheY-P levels caused by activation of the CheA kinase upon attractant binding to receptors, is brief due both to adaptational processes and to phosphatase activity of FliY.