Emerging meso- and macroscales from synchronization of adaptive networks.

We consider a set of interacting phase oscillators, with a coupling between synchronized nodes adaptively reinforced, and the constraint of a limited resource for a node to establish connections with the other units of the network. We show that such a competitive mechanism leads to the emergence of a rich modular structure underlying cluster synchronization, and to a scale-free distribution for the connection strengths of the units.

Incidence and clinical outcomes of ventilator-associated pneumonia in liver transplant and non-liver transplant surgical patients.

The aim of this study was to compare the incidence of ventilator-associated pneumonia (VAP) and clinical outcome among patients undergoing orthotopic liver transplantation (OLT) admitted to our surgical intensive care unit (ICU). Patients with an ICU stay longer than 4 days who had undergone surgery within 48 hours of admission were included in the study. Patients were subdivided into a liver transplant group (OLT) and no-liver transplant group (noLT). Diagnosis of VAP was based on microbiological data with a positive culture from a sample collected >or=48 hours after admission. VAP was defined as early if the positive culture occurred within the 4th day of admission, and late if after the 4th day. Three hundred seventy-three noLT and 71 OLT patients showed no differences in sex, mean severity score on admission (SAPS II), length of stay, and outcomes. The incidence of VAP was also similar in the 2 groups (27.3% in the noLT group vs 25.3% in the OLT group). Both in the OLT and noLT groups, the VAP patients showed higher (P< .05) SAPS II scores on admission, length of ICU stay, and mortality rates than the non-VAP patients, without any difference between the 2 groups. VAP is a frequent complication in ICU surgical patients, particularly those with high severity scores on admission. In an ICU surgical population, liver transplantation per se does not seem to increase the patients' risk either for VAP acquisition or for bad outcomes.

Comparison of high-performance liquid chromatographic serum profiles of humans and dogs.

The sera of 30 healthy male beagles were analyzed by reversed-phase high-performance liquid chromatography. The profiles were compared with those obtained from the sera of 30 healthy human donors. The chromatograms of each group were very reproducible; however, there were characteristic differences between the two groups. The compounds observed in both the human and canine profiles were identified as creatinine, uric acid, tyrosine, hypoxanthine, xanthine, kynurenine, inosine and tryptophan. Compounds present only in the canine profiles were identified as cytindine, riboflavin and 5-methyl-cytidine. Compounds present only in the human profiles include uridine, guanosine, hippuric acid and the dietary dependent compounds theobromine and caffeine. The compounds present in both human and canine sera were quantitated and compared statistically. The amounts of these compounds were very similar, except for uric acid.

Identification and quantitation of nucleosides, bases and other UV-absorbing compounds in serum, using reversed-phase high-performance liquid chromatography. I. Chromatographic methodology.

A comprehensive investigation of the high-performance liquid chromatographic separation of nucleosides, their bases and other low-molecular-weight UV-absorbing compounds that might be found in serum is reported. A buffer-methanol gradient was used in conjunction with chemically bonded, microparticulate columns to separate many of the biologically important compounds under study in minimal time with maximal resolution. Retention data, absorbance ratios (280/254 nm) and fluorescence responses are reported for 86 nucleosides, bases, nucleotides and other UV-absorbing compounds commonly encountered in biological studies.

Oculosympathetic alterations in migraine patients.

Oculosympathetic function was studied in 20 headache-free migraine patients and in 20 controls. Pupillary investigation was performed under basal conditions, and after instillation of tyramine (2%) and phenylephrine (1%) eyedrops. Each test was performed twice shortly after a spontaneous attack and then repeated after 7 and 15 days. In the patients, the normal mydriatic response induced by tyramine was significantly (p<0.001) reduced and phenylephrine instillation caused a significant (p<0.01) pupillary dilatation in both the assessments performed shortly after the attack. These abnormal responses were bilateral in all patients and slightly anisocoric in some. They were significantly (p<0.001) more pronounced in the patients who had pain and pronounced vascular features. The reduced oculosympathetic response to tyramine, as well as the hypersensitivity to phenylephrine, was less evident 7 days after the attack and absent after 15 days. A transient and bilateral post-ganglionic oculosympathetic hypofunction, with adrenoceptor hypersensitivity, was found to be temporally related to the migraine attack, regardless of the side or predominant side of pain.

Reversed-phase liquid chromatographic investigation of UV-absorbing low-molecular-weight compounds in saliva.

The reversed-phase mode of high-performance liquid chromatography was used to determine the intra- and inter-individual levels of UV-absorbing low-molecular-weight compounds in saliva. Many of the compounds known to occur in serum were also found in saliva; however, concentrations in saliva are lower. Both the intra- and inter-individual levels of these compounds vary significantly; in most cases, the inter-individual variance is 2-3 times the intra-individual variance. Caffeine and its metabolites in saliva are also reported. A greater number of metabolites were found in the saliva of habitual coffee drinkers. After caffeine was administered orally, paraxanthine, theobromine, theophylline, 1-methylxanthine, and 1-methyluric acid were found in the saliva of an individual who did not drink coffee regularly. In this subject, the serum half-life for caffeine was 3.49 h and the saliva half-life was 3.27 h. The half-life of caffeine in an habitual coffee drinker who had refrained from caffeine products for four days was 4.39 h.

Basilar migraine with electroencephalographic findings of occipital spike-wave complexes: a long-term study in seven children.

Basilar migraine is characterized by headache preceded by prodromal symptoms and signs of posterior cerebral circulation dysfunction. Few studies have focused on EEG findings in this condition or on the prognosis of occipital spike-wave complexes observed in either migraine or epilepsy. We now report a long-term follow-up (8-16 years) in seven children affected by basilar migraine who had EEG findings of occipital spike-wave complexes. Basilar migraine resolved and the EEG became normal in all subjects during the observation period, as did migraine with aura and seizures which developed in some of the patients after basilar migraine attacks ceased.

Reverse phase liquid chromatographic assay for calcium pantothenate in multivitamin preparations and raw materials.

A reverse phase liquid chromatographic (LC) method has been developed for the assay of calcium pantothenate in commercial multivitamin tablet formulations and raw materials. The assay was validated according to the Pharmaceutical Manufacturers Association Quality Control HPLC Committee guidelines. The chromatographic system includes a C-18 column and a mobile phase consisting of 0.25M sodium phosphate buffer, pH 2.5, and acetonitrile (97 + 3 v/v). The column effluent is monitored by UV detection at 205 nm. The sample preparation involves only extraction in water followed by filtration. The method is stability-indicating with a detection limit of approximately 50 ng/mL of the calcium pantothenate in the samples. The system is linear from at least 0.02 to 0.10 mg/mL. The mean recovery of spiked placebos ranged from 98.7 to 99.8%. The within-day precision of the assay on finished products (N = 6) ranged from 0.3 to 2.0% CV. A system suitability criterion for resolution is based on the separation between calcium pantothenate and 2 closely eluting compounds, saccharin and a saccharin degradation product, 2-sulfamoylbenzoic acid.

Trace analysis of diazepam in serum using microbore high-performance liquid chromatography and on-line preconcentration.

The feasibility of determining trace analytes in human serum using on-line preconcentration and microbore high-performance liquid chromatography has been demonstrated. The serum is subjected to ultracentrifugation and injected onto a hydrophobic pre-column using water as the mobile phase. This traps the components of interest which are then backflushed onto a microbore analytical column using a stronger mobile phase. The column-switching apparatus was evaluated using highly dilute aqueous paraben solutions and sample enrichment factors as high as 1500 were obtained. The procedure was then applied to diazepam in serum. Recovery was linear and quantitative over the range from at least 4 to 1000 ng/ml. The method was specific against caffeine and the three major metabolites of diazepam: oxazepam, temazepam, and nordiazepam. The effects of varying pre-column dimensions, pre-column loading time, and sample volume were evaluated.

Migraine and epilepsy with infantile onset and electroencephalographic findings of occipital spike-wave complexes.

An EEG finding of temporo-occipital or temporo-parieto-occipital spike-wave complexes, suppressed by eye opening, coexisting with classical migraine, was observed in 14 children; in 13 of these patients, seizures were present. Classical migraine, visual phenomena and seizures coexisted in different clinical patterns.

Tension type headache: a neuropsychological and neurophysiological study.

Characteristic personality profiles of patients suffering from either migraine headache (MH) or tension type headache (TTH) have been described in the light of Minnesota Multiphasic Personality Inventory (MMPI). In the present study we evaluated personality profile changes following modifications of the painful symptoms after treatment, through the administration of the MMPI to MH and TTH patients. In TTH patients with no clinical improvement the depression scale scores were higher after 6 months of treatment, whereas in MH patients similar scores were observed before and after therapy, thus suggesting a primary role of depression in the onset of pain in the latter patients. Computerized EMG recording of the neck muscle activity showed different patterns of muscle contraction in resting condition and during stress or maximal muscular activity in patients suffering from TTH as compared to MH patients and normal subjects.

Relationship among physicochemical properties, skin permeability, and topical activity of the racemic compound and pure enantiomers of a new antifungal.

The topical antifungal Sch-39304 is a racemic compound comprised of two enantiomers, Sch-42427 and Sch-42426, only one of which (Sch-42427) is pharmacologically active. The pure enantiomers have a lower melting point and, therefore, a higher solubility than the racemic compound. Because of these differences in physicochemical properties, the concentration of the pure enantiomers in vehicles and in the skin was predicted to be an order of magnitude higher than the racemic compound. It was hoped that the pharmacological activity would also be higher. By measuring the flux of the chiral forms through human cadaver skin, the expected differences in skin solubility were confirmed. However, only a minimal difference between racemate and active enantiomer was observed in the lesion scores using a guinea pig dermatophyte model. By fitting the data to the Emax pharmacodynamic model, it is demonstrated that the maximum effect occurs at a concentration lower than the saturated concentration of the less soluble racemic compound. The data illustrate that the efficacy of topically active compounds may not be linearly related to drug concentration in either the vehicle or the skin.