The interference effects of hexadecylphosphocholine on proliferation and membrane phospholipid metabolism in human myeloid leukemia cell lines

Membrane phospholipids are important regulators of cellular function. The phospholipid activities, such as lipid composition and transportation, contribute to cellular homeostasis in the lifespan of cells. Alterations in phospholipids result in the movement of bilayer lipids and the initiation of coagulation, recognition and internalization. Hexadecylphosphocholine (HePC) exerts antitumor potencies and represents a new class of antitumor agents targeted to the cellular membrane. Human myeloid leukemia cell lines HL-60 and K562 employed in this study were inhibited by HePC in vitro. The results indicate that the HL-60 cell line was sensitive, while K562 was resistant to HePC. Synthetic HePC is an alkyllysophospholipid analog which interacted with the cell membrane, thereby altering lipid composition and metabolism of membrane phospholipids and modulating intracellular calcium in human myeloid leukemia HL-60 and K562 cell lines. The contents of membrane phospholipids, including phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylethanolamine (PE), were determined quantitatively with high performance liquid chromatography. The sensitivity of myeloid leukemia HL-60 and K562 cell lines to HePC probably depends on the different distribution of these four phospholipids in the cellular membrane, or on the response of these phospholipids to HePC. The cytosolic free calcium ([Ca++]i) concentration increased by HePC confirmed that [Ca++]i was released from the intracellular calcium pool and is associated with cell differentiation and apoptosis. We investigated the hypothesis that the antiproliferative effect of HePC was mediated through the interference with cellular membrane phospholipids, including choline-containing phospholipids (PC), aminophospholipids (PE and PS) and PI, in eukaryotic cells.     

Adding a temporal dimension to a logic system

We introduce a methodology whereby an arbitrary logic system L can be enriched with temporal features to create a new system T(L). The new system is constructed by combining L with a pure propositional temporal logic T (such as linear temporal logic with Since and Until) in a special way. We refer to this method as adding a temporal dimension to L or just temporalising L. We show that the logic system T(L) preserves several properties of the original temporal logic like soundness, completeness, decidability, conservativeness and separation over linear flows of time. We then focus on the temporalisation of first-order logic, and a comparison is make with other first-order approaches to the handling of time.     

Levels of thermostable direct hemolysin production by Vibrio parahaemolyticus strains carrying both tdh and trh genes

One hundred and twenty-five strains of Vibrio parahaemolyticus carrying both the tdh and trh genes were selected from the strains isolated from the travelers with diarrhea by an hybridization test using polynucleotide probes. The levels of TDH produced by these strains and the association between the TDH levels and related characteristics in these strains were analyzed. The TDH level varied greatly from strain to strain, but none of the levels was as high as that of the typical Kanagawa phenomenon-positive strains. The strains were classified into "TDH producer" (18 strains), "Low-level TDH producer" (85 strains), and "No TDH producer" (22 strains) based on the results of a modified Elek test and the hemolysis assay on Wagatsuma agar. The highest TDH level achieved by the "TDH producer" was twofold lower than that of the Kanagawa phenomenon-positive strains as assayed by the RPLA method. All strains possessed the toxR gene. The trh1 and trh2 genes were detected in, respectively, 105 and 20 strains, and no correlation existed between the type of the trh gene and the levels of TDH produced. Considerable restriction fragment length polymorphism was observed with the tdh gene-bearing HindIII DNA fragment in different strains, but it was not related with the TDH level.     

Timing of surgery in patients with aneurysmal subarachnoid haemorrhage: rebleeding is still the major cause of poor outcome in neurosurgical units that aim at early surgery

OBJECTIVE: To investigate prospectively the proportion of patients actually operated on early in units that aim at surgery in the acute phase of aneurysmal subarachnoid haemorrhage (SAH) and what is the main current determinant of poor outcome. METHODS: A prospective analysis of all SAH patients admitted during a one year period at three neurosurgical units that aim at early surgery. The following clinical details were recorded: age, sex, date of SAH, date of admission to the neurosurgical centre, whether a patient was referred by a regional hospital or a general practitioner, Glasgow coma scale and grade of SAH (World Federation of Neurological Surgeons (WFNS) score) on admission at the neurosurgical unit, results of CT and CSF examination, the presence of an aneurysm on angiography, details of treatment with nimodipine or antifibrinolytic agents, and the date of surgery to clip the aneurysm. At follow up at three months, the patients' clinical outcome was determined with the Glasgow outcome scale and in cases of poor outcome the cause for this was recorded. RESULTS: The proportion of patients that was operated on early--that is, within three days after SAH--was 55%. Thirty seven of all 102 admitted patients had a poor outcome. Rebleeding and the initial bleeding were the main causes of this in 35% and 32% respectively of all patients with poor outcome. CONCLUSIONS: In neurosurgical units with what has been termed "modern management" including early surgery, about half of the patients are operated on early. Rebleeding is still the major cause of poor outcome.     

Kinetics of the thermal oxidation of isotactic poly(1-pentene)

The kinetics of the thermal oxidation of isotactic poly(1-pentene) was studied in the bulk phase. The experimental data were obtained from the quantitative estimation of carbonyl groups formed in the non-volatile oxidation products using infra-red spectroscopy. Reaction temperature varied from 100° to 115° and oxygen concentrations from 10% to 100% by volume. A general kinetic scheme and mathematical expressions previously reported for the thermal autoxidation of polyolefins satisfactorily explained the experimental results. Activation energies of this polymer for various steps in the kinetic scheme were compared with polypropylene and poly(1-butene).     

Curry-Howard for incomplete first-order logic derivations using one-and-a-half level terms

The Curry-Howard correspondence connects derivations in natural deduction with the lambda-calculus. Predicates are types, derivations are terms. This supports reasoning from assumptions to conclusions, but we may want to reason backwards; from the desired conclusion towards the assumptions. At intermediate stages we may have a partial derivation, with holes.This is natural in informal practice but it can be difficult to formalise. The informal act of filling holes in a partial derivation suggests a capturing substitution, since holes may occur in the scope of quantifier introduction rules. As other authors have observed, this is not immediately supported by the lambda-calculus. Also, universal quantification requires a ‘fresh name’ and it is not immediately obvious what formal meaning to assign to this notion if derivations are incomplete. Further issues arise with proof-normalisation; this corresponds with lambda-calculus reduction, which can require alpha-conversion to avoid capture when beta-reducing, and it is not immediately clear how to alpha-convert a name in an incomplete derivation. We apply a one-and-a-half level technique based on nominal terms to construct a Curry-Howard correspondence for first-order logic. This features two levels of variable, but with no lambda-abstraction at the second level. Predicates are types, derivations are terms, proof-normalisation is reduction — and the two levels of variable are, respectively, the assumptions and the holes of an incomplete derivation.We give notions of proof-term, typing, alpha-conversion and beta-reduction for our syntax. We prove confluence, we exhibit several admissible rules including a proof that instantiation of level two variables is type-safe — this corresponds with the act of filling holes in an incomplete derivation, and can be viewed as a form of Cut-rule — and we explore the connection with traditional Curry-Howard in the case that the derivation is in fact complete.Our techniques are not specifically tailored to first-order logic and the same ideas should be applicable without any essential new difficulties to similar logical systems.     

Epilepsia partialis continua: a new manifestation of anti-Hu-associated paraneoplastic encephalomyelitis

We report on 3 anti-Hu-positive patients who presented with clinical and electroencephalographic (EEG) features of epilepsia partialis continua (EPC). Two of the patients had an associated small cell carcinoma. Magnetic resonance imaging (MRI) disclosed a hyperintense nonenhancing focal lesion in T2-weighted images in the sensorimotor area in 2 patients. Histopathological analysis of the lesion revealed inflammatory infiltrates and neuronal cell loss. In the patient who had a postmortem study, these neuropathological changes were not observed in other areas of the nervous system. This study emphasizes that the possibility of an anti-Hu-associated paraneoplastic disorder must be considered in patients with cortical encephalitis presenting with EPC when a brain tumor can be excluded.