Reaction of cytochrome P450 with cumene hydroperoxide: ESR spin-trapping evidence for the homolytic scission of the peroxide O-O bond by ferric cytochrome P450 1A2

ESR spin trapping was used to investigate the reaction of rabbit cytochrome P450 (P450) 1A2 with cumene hydroperoxide. Cumene hydroperoxide-derived peroxyl, alkoxyl, and carbon-centered radicals were formed and trapped during the reaction. The relative contributions of each radical adduct to the composite ESR spectrum were influenced by the concentration of the spin trap. Computer simulation of the experimental data obtained at various 5,5-dimethyl-1-pyrroline N-oxide (DMPO) concentrations was used to quantitate the contributions of each radical adduct to the composite ESR spectrum. The alkoxyl radical was the initial radical produced during the reaction. Experiments with 2-methyl-2-nitrosopropane identified the carbon-centered adducts as those of the methyl radical, hydroxymethyl radical, and a secondary carbon-centered radical. The reaction did not require NADPH-cytochrome P450 reductase or NADPH. It is concluded that the reaction involves the initial homolytic scission of the peroxide O-O bond to produce the cumoxyl radical. Methyl radicals were produced from the beta-scission of the cumoxyl radical. The peroxyl adduct was not observed in the absence of molecular oxygen. We conclude that the DMPO peroxyl radical adduct detected in the presence of oxygen was due to the methylperoxyl radical formed by the reaction of the methyl radical with oxygen. At a higher P450 concentration, a protein-derived radical adduct was also detected.     

Health status of the over 60 years of age population and its relationship with sociodemographic factors (ANCO Project)

OBJECTIVE: To describe the health status of a population over 60 years and to study their relationship with several socio-demographic variables. DESIGN: A cross-sectional study, population based. SETTINGS: A community. PARTICIPANTS: A randomized sample of 1,103 non institutionalized people over 60 years living in the city of Cordoba (Spain). MEASUREMENTS AND MAIN RESULTS: By mean of a personal interview at home we used the OARS-MFAQ-VE questionnaire. Low self-rated health was associated with the age, to be female sex, a low cultural background, and a low income. Only 5.2% of the study people do not suffered any illness and 56% state that their health problems are major problems for doing their current activities. 4.9% declared to have some degree of physical incapacity. 3.7% of elderly population has an important cognitive deficit. CONCLUSIONS: The majority of elderly people has good health. Age is related with a poor health. Women have more health problems than men.     

The role of interparticle forces in colloidal aggregates: local investigations and modelling of restructuring during filtration.

Industrial solid-liquid separation processes, such as pressure filtration or membrane processes, involve the application of pressure to suspensions. In response, some water is extracted, the suspension volume is reduced, and the dispersed aggregates start to form a network. In recent works, we aimed to make a prediction for the response of aggregates to stress which occurs during a filtration. We chose model systems made of aggregated silica nanoparticles. Some of these systems offer a strong resistance to applied stresses, and retain their permeability; others yield and collapse. We used small angle neutron scattering by which we can locally quantify the particle distribution withi the network to determine the processes by which particles reorganise during collapse: we found that reordering processes at the scale of 1 to 10 particle diameters control the course of collapse and the loss of permeability. Finally we constructed a numerical model for describing the processes by which colloidal aggregates are compressed. This model predicts that the response of such networks to pressure follows some scaling laws, which depend only on the elastic vs. dissipative nature of interparticle bonds.     

Effects of volatile anesthetics on the kinetics of inhibitory postsynaptic currents in cultured rat hippocampal neurons

1. The effects of the volatile anesthetics enflurane, halothane, and isoflurane on gamma-aminobutyric acid (GABA) receptor-mediated inhibitory postsynaptic currents (IPSCs) were studied in cultured rat hippocampal neurons. The experimental concentrations of anesthetics were measured directly using gas chromatography. All three anesthetics increased the overall duration of IPSCs, measured as the time to half-decay (T1/2). Clinically effective concentrations of anesthetics [between 0.5 and 1.5 times MAC (minimum alveolar concentration)] produced between 100 and 400% increases in T1/2. These effects were fully reversible, and did not involve alterations in the reversal potential for the IPSC (EIPSC). 2. The decay of the IPSC was fitted as a sum of two exponential functions, yielding a fast component (tau fast = 20 ms), and a slow component (tau slow = 77 ms), such that the fast component accounted for 79% of the IPSC amplitude and 52% of the total charge transfer. All three anesthetics produced concentration-related increases in the amplitude and charge transfer of the slow component, while simultaneously decreasing the amplitude and charge transfer of the fast component. Thus T1/2 approximated tau fast under control conditions, but approximated tau slow in the presence of the anesthetics. 3. Varying the calcium chelating agents in the recording pipettes had no effect on the quality or magnitude of alterations in IPSC kinetics produced by halothane, suggesting that variations in intracellular calcium levels are not required for the effect of halothane on the time course of the IPSC. 4. The (+)-stereoisomer of isoflurane produced greater increases in the duration of the IPSC than the (-)-isomer when applied at approximately equal concentrations, suggesting that there is a structurally selective site of interaction for isoflurane that modulates the GABAA receptor. 5. These results suggest that the previously shown abilities of volatile anesthetics to potentiate responses to exogenously applied GABA and to prolong the duration of GABA-mediated synaptic inhibition may be due to an alteration in the gating kinetics of the GABAA receptor/channel complex. Prolongation of synaptic inhibition in the CNS is consistent with the physiological effects that accompany anesthesia and may contribute to the mechanism of anesthetic action.     

Chronic abdominal pain: role of video-laparoscopic adhesiolysis

Adhesions have been suggested as a possible cause of chronic abdominal pain, but the reports of their etiological role conflict. Lysis of adhesions has been proposed as the therapeutic modality of choice, although the reports of success are controversial. The aim our prospective study was to determine whether laparoscopic adhesiolysis ameliorates chronic abdominal pain in patients with abdominal adhesions. Forty-one patients with chronic abdominal pain lasting for more than 6 months, but with no abnormal findings other than adhesions found at laparoscopy, underwent laparoscopic adhesiolysis. 37 patients (90.2%) were available for follow-up after a median time interval of 18 months (range: 12-41 months). Twenty-two patients (59.4%) were free from abdominal pain and 9 (24.3%) patients reported significant amelioration of their pain. Six (16.2%) patients had no amelioration. In conclusion the laparoscopy is an effective tool for the evaluation of patients with chronic abdominal pain, and laparoscopic adhesiolysis cures of ameliorates chronic abdominal pain in more than 80% of patients.