Hysteresis and the dynamic phase transition in thin ferromagnetic films

Hysteresis and the nonequilibrium dynamic phase transition in thin magnetic films subject to an oscillatory external field have been studied by Monte Carlo simulation. The model under investigation is a classical Heisenberg spin system with a bilinear exchange anisotropy Lambda in a planar thin film geometry with competing surface fields. The film exhibits a nonequilibrium phase transition between dynamically ordered and dynamically disordered phases characterized by a critical temperature T(cd), whose location is determined by the amplitude H0 and frequency omega of the applied oscillatory field. In the presence of competing surface fields the critical temperature of the ferromagnetic-paramagnetic transition for the film is suppressed from the bulk system value T(c) to the interface localization-delocalization temperature T(ci). The simulations show that in general T(cd)<T(ci) for the model film. The profile of the time-dependent layer magnetization across the film shows that the dynamically ordered and dynamically disordered phases coexist within the film for T<T(cd). In the presence of competing surface fields, the dynamically ordered phase is localized at one surface of the film.

Psychometric evaluation of the exercise self-efficacy scale among Korean adults with chronic diseases

The purpose of this study was to assess the psychometric properties, appropriateness, and demographic response patterns of an exercise self-efficacy scale for Korean adults with chronic diseases. After assessment of face validity by an expert Korean panel, 249 Korean adults with chronic diseases, ages 18-79 years, were recruited from hospitals or health centers in five Korean cities and surrounding rural areas to complete the questionnaire. In a factor analysis the original 18-item exercise self-efficacy scale converged to one factor without rotation and to three subfactors with rotation: situational/interpersonal factor, competing demands factor, and internal feelings factor. Descriptive analysis showed that Korean adults with chronic diseases perceived they had relatively low exercise self-efficacy, with the situational/interpersonal factor as the lowest factor. Exercise self-efficacy was significantly correlated with gender, education, regular exercise, and frequency of exercise. The exercise self-efficacy scale was shown to be a useful measure of exercise beliefs of Korean adults with chronic diseases.

Preoperative detection of hepatocellular carcinoma: ferumoxides-enhanced mr imaging versus combined helical CT during arterial portography and CT hepatic arteriography

OBJECTIVE

The purpose of this study was to compare ferumoxides-enhanced MR imaging with combined helical CT during arterial portography and CT hepatic arteriography for preoperative detection of hepatocellular carcinomas.

SUBJECTS AND METHODS

Twenty patients with 30 hepatocellular carcinomas underwent ferumoxides-enhanced MR imaging and combined helical CT during arterial portography and CT hepatic arteriography. The diagnosis was established by pathologic examination after surgical resection in 18 patients and by biopsy in two. The MR protocol included fast spin-echo with two echo times, T2(*)-weighted fast multiplanar gradient-recalled acquisition in the steady state, proton density-weighted fast multiplanar spoiled gradient-recalled echo, and T1-weighted fast multiplanar spoiled gradient-recalled echo images. The MR images of all sequences and the paired CT during arterial portography and CT hepatic arteriography images were independently evaluated by three radiologists on a segment-by-segment basis. Diagnostic accuracy was assessed with receiver operating characteristic analysis.

RESULTS

The accuracies (A(z) values) of ferumoxides-enhanced MR imaging and combined CT during arterial portography and CT hepatic arteriography for all observers were 0.964 and 0.948, respectively. The mean sensitivities of MR imaging and CT were 93% and 91%, respectively. The differences were not statistically significant. The mean specificity of MR imaging (99%) was significantly higher than that of combined CT during arterial portography and CT hepatic arteriography (94%).

CONCLUSION

Ferumoxides-enhanced MR imaging can be used successfully in place of combined CT during arterial portography and CT hepatic arteriography for the preoperative evaluation of patients with hepatocellular carcinomas.

Detection and identification of mycobacteria by amplification of the internal transcribed spacer regions with genus- and species-specific PCR primers

We evaluated the usefulness of PCR assays that target the internal transcribed spacer (ITS) region for identifying mycobacteria at the species level. The conservative and species-specific ITS sequences of 33 species of mycobacteria were analyzed in a multialignment analysis. One pair of panmycobacterial primers and seven pairs of mycobacterial species-specific primers were designed. All PCRs were performed under the same conditions. The specificities of the primers were tested with type strains of 20 mycobacterial species from the American Type Culture Collection; 205 clinical isolates of mycobacteria, including 118 Mycobacterium tuberculosis isolates and 87 isolates of nontuberculous mycobacteria from 10 species; and 76 clinical isolates of 28 nonmycobacterial pathogenic bacterial species. PCR with the panmycobacterial primers amplified fragments of approximately 270 to 400 bp in all mycobacteria. PCR with the M. tuberculosis complex-specific primers amplified an approximately 120-bp fragment only for the M. tuberculosis complex. Multiplex PCR with the panmycobacterial primers and the M. tuberculosis complex-specific primers amplified two fragments that were specific for all mycobacteria and the M. tuberculosis complex, respectively. PCR with M. avium complex-, M. fortuitum-, M. chelonae-, M. gordonae-, M. scrofulaceum-, and M. szulgai-specific primers amplified specific fragments only for the respective target organisms. These novel primers can be used to detect and identify mycobacteria simultaneously under the same PCR conditions. Furthermore, this protocol facilitates early and accurate diagnosis of mycobacteriosis.

Surface-induced ordering in thin uniaxial liquid crystal films

The interface localization transition in thin uniaxial liquid crystal films with competing surface fields has been studied using Metropolis Monte Carlo simulations. The model is constructed from a lattice of continuously orientable interacting spins, and the Hamiltonian contains both bilinear and biquadratic contributions. The biquadratic contribution to the Hamiltonian is familiar from the Lebwohl-Lasher model, and accounts for the particle anisotropy in a liquid crystal. The head-tail asymmetry of the molecules in a uniaxial liquid crystal is taken into account through a bilinear contribution familiar from the classical ferromagnetic Heisenberg model with exchange anisotropy Lambda. The critical temperature T(c), characterizing the interface localization transition within the uniaxial liquid crystal film, depends strongly on the relative magnitudes of the bilinear and biquadratic interactions between the spins. For systems dominated by the biquadratic interaction, T(c) is found to be close to the bulk critical temperature of the system. But as the biquadratic interaction strength is reduced, T(c) departs markedly from the bulk critical temperature of the system.

A patient with genetic deletion of glutathione-S-transferase T1 and M1 who developed non-small-cell lung cancer and myelodysplastic syndromes

Glutathione S-transferase (GST) M1 polymorphism is a marker for susceptibility to smoking-related neoplasms, such as lung and bladder cancer. Recently, a genetic deletion of GSTT1, an isoenzyme of GST, has been reported to be associated with myelodysplastic syndromes (MDS). A 59-year-old man with a long-term smoking habit was treated successfully for non-small-cell lung cancer. Four years after the surgical removal of his lung cancer, he developed MDS and died. Using a polymerase chain reaction-based genotyping method, he was found to have a deletion of both the GSTM1 and GSTT1 genes. Screening for the deletion of the GSTM1 and GSTT1 genes may be useful for assessing individual genetic susceptibility to smoking-related lung cancer and MDS.

Safety, tolerability, and pharmacokinetics of SR 49059, a V1a vasopressin receptor antagonist, after repeated oral administration in healthy volunteers

The conventional evaluation of safety and tolerability during Phase I may not be sufficient for new exploratory non-peptide receptor antagonists as selective vasopressin (AVP) receptor antagonists. Previous research and validation of surrogate markers considerably enhance the understanding of phase I, and may even contribute with high accuracy to an early approach of dose finding. SR 49059 is a new potent and selective non peptide AVP-antagonist, with high affinity, selectivity and efficacy towards both animal and human AVP-V1a receptors. The aim of this study was to assess its tolerability and to determine both its pharmacokinetic and pharmacodynamic profiles. The safety and tolerability of SR 49059 was assessed in an ascending repeated dose tolerability trial, double-blind for each dose. 50 healthy subjects non smoker males, divided into 5 groups (doses) of 10 were included, (8 treated/2 placebo per group) and received oral doses of either 1, 10, 100, 300 or 600 mg of SR 49059 o.d. for 7 days. Clinical tolerability and biological safety was excellent for all subjects up to the highest dose of 600 mg SR 49059 appeared to have no action on AVP plasma level, hemostasis parameters, nor on blood pressure, heart rate, ECG, diuresis or plasma/urine osmolality. Two previously validated surrogate markers using exogenous vasopressin were sufficient to provide evidence of the V1a antagonistic effects of SR 49059 after the first single oral administration, and during the 7 days of treatment: Ex-vivo AVP induced platelet aggregation inhibition: SR 49059 has shown potent antagonistic properties in inhibiting AVP-induced human platelet aggregation in vitro (IC50 = 3.7 nM). Using this ex vivo qualitative test, a dose and time proportional activity was observed at doses as low as 10 mg, and an almost complete inhibition was demonstrated from 100 mg and above, from Day 1 with a steady state level of inhibition from Day 4 up to Day 7. AVP induced blanching skin area inhibition: Intradermic administration of AVP 0.1 ml (25 ng) produced a measurable vasoconstriction (computer analysis of blanching area), which was also dose dependently antagonised by the oral administration of SR 49059 with the same profile as for platelet-aggregation inhibition. Steady state SR 49059 levels were achieved on days 4-5 with moderate (1.8-2.4 fold) accumulation (t1/2: 32 hrs). Cmax values were in the range 0.8-30 ng/ml. The IC50 of AVP (50 nM) -induced platelet aggregation and cutaneous blanching effect were 2.1 +/- 0.7 nM (1.3 ng/mL) and 4.6 +/- 2.5 nM (2.8 ng/mL), respectively.

CONCLUSIONS

During early phase I, in addition to the conventional safety profile, validated surrogate markers may provide evidence of activity for selective vasopressin receptor antagonists. The results confirmed that SR 49059 is in human a specific V1a-antagonist without activity at V2 receptors, with a good safety profile.

The incidence of the factor V Leiden mutation in an obstetric population and its relationship to deep vein thrombosis

OBJECTIVE

A common missense mutation in the factor V gene, the Leiden mutation, renders factor Va resistant to cleavage inactivation by activated protein C and predisposes patients to thrombotic events. We sought to evaluate the prevalence of the Leiden mutation and the associated thromboembolic events in a community hospital's low-risk obstetric population.

STUDY DESIGN

Deoxyribonucleic acid was extracted from whole blood of 407 women. The polymerase chain reaction was used to amplify exon 10 of the factor V gene, followed by enzymatic digestion with MnI 1 for mutation detection. Medical charts were reviewed and patient characteristics, including age, gravidity, parity, obstetric complications, medical complications, and mode of delivery, were recorded.

RESULTS

Fourteen of the 407 women carried the factor V Leiden mutation (13 heterozygotes and 1 homozygous mutant) for an allele frequency of 3%, consistent with the published carrier rate. Four of the 14 carriers (28%) had deep venous thrombosis, whereas the frequency of deep venous thrombosis in this obstetric population was <1%. Another patient carrying the mutation had a consumptive coagulopathy of unknown etiology at 20 weeks' gestation, necessitating delivery.

CONCLUSIONS

The Leiden mutation is relatively common in the general obstetric population. The high rate of deep venous thrombosis noted in our series suggests the need for genetic testing for this mutation in women with a thrombotic event during pregnancy.

Setaria marshalli infection in neonatal calves

A total of 50 filariid worms of Setaria spp. was recovered from the peritoneal cavity of three neonatal calves infected with the Akabane virus. The parasites were identified as S. marshalli by their morphological characteristics. Males were 41-52 mm long and females 68-98 mm. Most of them were fully matured, indicating that the calves were infected prenatally. This is the first report of prenatal infection in calves by S. marshalli in Korea.

A compartmental model predicts that dietary potassium affects lithium dynamics in rats

Lithium is the treatment of choice for manic depression, but therapy often results in nephrogenic diabetes insipidus and lithium intoxication. To investigate the effects of dietary potassium on potential side effects of lithium therapy, a mathematical model was built using the modeling program SAAM (Simulation, Analysis, And Modeling). Experimental data modeled were from adult male Sprague-Dawley rats fed diets with or without lithium and one of three levels of potassium for 17 d. A five-compartment model of lithium dynamics was built that was consistent with data from rats fed a lithium-containing diet adequate in potassium. This model was then compared with data from rats fed the other two lithium-containing diets. The model predicts that both the fractional transfer coefficient and rate of transport of lithium to the serum compartment from the kidney compartment are lower in rats fed the potassium-adequate diet than in those fed the potassium-deficient diet, and even lower in those fed the potassium-supplemented diet. In addition, fractional transfer coefficients into the serum compartment from the sampled and simulated tissue compartments changed differently with time depending on the amount of dietary potassium. The model also predicts that there would be less accumulation of lithium in the kidney, sampled tissue and simulated tissue compartments with supplemental dietary potassium. The model suggests that potassium supplementation, after a 7-d delay, protects against nephrogenic diabetes insipidus and the potentially toxic accumulation of lithium by decreasing the reabsorption of lithium from the kidneys and increasing lithium efflux from the tissues.

Aspirin dosing using 15 grain enteric coated tablets

A high unit dose (15 grain/975 mg) enteric coated aspirin preparation was studied in normal individuals and patients with arthritis to determine how readily well tolerated, therapeutic (150-300 micrograms/ml) salicylate (SA) levels could be achieved using a twice daily dosing regimen. Of 36 participants enrolled, 33 (92%) achieved this goal (mean SA = 224 micrograms/ml), while in the remaining 3 an initially toxic level fell below the therapeutic range after reducing the dose by one tablet/day. Although the relationship between dose (mg/kg) and steady state SA levels was roughly linear (r = 0.74), in some subjects there was a striking incremental change in the SA level when the dose was adjusted. Over 90% of subjects taking a starting dose between 45-60 mg/kg/day achieved a therapeutic level. Thus, antiinflammatory therapy using 15 grain/975 mg enteric coated aspirin given twice daily appears to be feasible.

Effects of chlordane isomers administered to female mice during the neonatal period

In consideration of the influence that chlorinated hydrocarbon insecticides may exert on mammalian physiology, the present study was performed to investigate the effects of neonatal chlordane administration on body growth and endocrine development in female mice. Mice receiving 0.075 or 0.15 mg of alpha or gamma chlordane on day 2, 3, and 4 of life were observed to have growth rates depressed to varying extents depending on the concentration or the type of isomer that was utilized. Eye and vaginal opening in the neonatally treated mice were observed to be delayed to varying degrees, which were dependent on which isomer was used. The total effects observed in the neonatally treated mice were not found to reflect a dose-related response.