Thermodynamic properties of the spin S=3/2 quantum ferromagnetic Blume-Capel model in a transverse crystal field.

The thermodynamic properties of the spin S=3/2 ferromagnetic Ising model in the presence of transverse and longitudinal crystal fields (equivalent to the Blume-Capel model with a transverse crystal field) have been studied by using two different approaches: (i) a zero-temperature mapping of the system onto a spin-1/2 quantum Ising model in longitudinal and transverse fields, together with time-independent quantum perturbation theory; and (ii) a standard mean-field approximation within the framework of the Bogoliubov inequality for the free energy. A very rich phase diagram, with different kinds of multicritical behavior, has been obtained. The results show first- and second-order transition lines, tricritical and tetracritical points, critical end points with a two-phase coexistence, double critical end points, and also double noncritical end points. Additionally, the behavior of the magnetization as a function of temperature, over a wide range of values of both longitudinal and transverse crystal fields, has also been analyzed in detail. While large magnitudes of the longitudinal crystal field select the z-spin components either in their states ±3/2 or ±1/2, it is surprising that a large transverse crystal field induces the spin component in the z direction to values ±1, which are completely different from any expected natural component. This comes indeed as a result of the zero-temperature mapping of the ground state with the superposition of the states 3/2 and -1/2, in one sector of the Hilbert space, and the states -3/2 and 1/2 on the other disjoint sector of the Hilbert space. This superposition for a large transverse crystal field prevails even for finite temperatures, implying that the exact critical points are obtained for the model on the one-dimensional lattice and the two-dimensional square lattice, and quite accurate estimates can be achieved for the three-dimensional simple cubic lattice.

A novel holistic framework for genetic-based captive-breeding and reintroduction programs.

Research in reintroduction biology has provided a greater understanding of the often limited success of species reintroductions and highlighted the need for scientifically rigorous approaches in reintroduction programs. We examined the recent genetic-based captive-breeding and reintroduction literature to showcase the underuse of the genetic data gathered. We devised a framework that takes full advantage of the genetic data through assessment of the genetic makeup of populations before (past component of the framework), during (present component), and after (future component) captive-breeding and reintroduction events to understand their conservation potential and maximize their success. We empirically applied our framework to two small fishes: Yarra pygmy perch (Nannoperca obscura) and southern pygmy perch (Nannoperca australis). Each of these species has a locally adapted and geographically isolated lineage that is endemic to the highly threatened lower Murray-Darling Basin in Australia. These two populations were rescued during Australia's recent decade-long Millennium Drought, when their persistence became entirely dependent on captive-breeding and subsequent reintroduction efforts. Using historical demographic analyses, we found differences and similarities between the species in the genetic impacts of past natural and anthropogenic events that occurred in situ, such as European settlement (past component). Subsequently, successful maintenance of genetic diversity in captivity-despite skewed brooder contribution to offspring-was achieved through carefully managed genetic-based breeding (present component). Finally, genetic monitoring revealed the survival and recruitment of released captive-bred offspring in the wild (future component). Our holistic framework often requires no additional data collection to that typically gathered in genetic-based breeding programs, is applicable to a wide range of species, advances the genetic considerations of reintroduction programs, and is expected to improve with the use of next-generation sequencing technology.

Testing monophyly of the freshwater fish Leporinus (Characiformes, Anostomidae) through molecular analysis.

Monophyly of the genus Leporinus (Characiformes: Anostomidae) was tested by sequencing and analysing a total of 4732 bp, including two mitochondrial [cytochrome oxidase subunit 1 (CO1) and cytochrome b (Cytb)] and three nuclear [myosin heavy chain 6 cardiac muscle alpha (Myh6), recombination activating gene 1 (RAG1) and recombination activating gene 2 (RAG2)] loci for 22 species of Leporinus, or c. 25% of all described species in the genus. Phylogenetic tree analyses (maximum parsimony, maximum likelihood and Bayesian species tree) indicate Leporinus to be paraphyletic, with monophyly being rejected by both Kishino-Hasegawa and Shimodaira-Hasegawa tests. The sequenced species of Leporinus are distributed across five clades that are interleaved among other anostomid genera. Several taxonomic changes are suggested as being necessary to restore monophyly for the group. The clade containing the type species, Leporinus fasciatus, should be considered Leporinus sensu stricto and at least three new genera should be described for other species currently considered part of Leporinus.

DNA barcoding and morphological identification of neotropical ichthyoplankton from the Upper Paraná and São Francisco.

The identification of fish larvae from two neotropical hydrographic basins using traditional morphological taxonomy and DNA barcoding revealed no conflicting results between the morphological and barcode identification of larvae. A lower rate (25%) of correct morphological identification of eggs as belonging to migratory or non-migratory species was achieved. Accurate identification of ichthyoplankton by DNA barcoding is an important tool for fish reproductive behaviour studies, correct estimation of biodiversity by detecting eggs from rare species, as well as defining environmental and management strategies for fish conservation in the neotropics.

Quantum spin-1 anisotropic ferromagnetic Heisenberg model in a crystal field: a variational approach.

A variational approach based on Bogoliubov inequality for the free energy is employed in order to treat the quantum spin-1 anisotropic ferromagnetic Heisenberg model in the presence of a crystal field. Within the Bogoliubov scheme an improved pair approximation has been used. The temperature-dependent thermodynamic functions have been obtained and provide much better results than the previous simple mean-field scheme. In one dimension, which is still nonintegrable for quantum spin-1, we get the exact results in the classical limit, or near-exact results in the quantum case, for the free energy, magnetization, and quadrupole moment, as well for the transition temperature. In two and three dimensions the corresponding global phase diagrams have been obtained as a function of the parameters of the Hamiltonian. First-order transition lines, second-order transition lines, tricritical and tetracritical points, and critical endpoints have been located through the analysis of the minimum of the Helmholtz free energy and a Landau-like expansion in the approximated free energy. Only first-order quantum transitions have been found at zero temperature. Limiting cases, such as isotropic Heisenberg, Blume-Capel, and Ising models, have been analyzed and compared to previous results obtained from other analytical approaches as well as from Monte Carlo simulations.

N-acetyl transferase 2 and cytochrome P450 2E1 genes and isoniazid-induced hepatotoxicity in Brazilian patients.

SETTING: Isoniazid (INH) is related to the development of hepatotoxicity in some patients. OBJECTIVE: To investigate the role of N-acetyl transferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) in the hepatotoxicity of patients treated with INH in an Amazonian Brazilian population. DESIGN: Patients undergoing anti-tuberculosis treatment were investigated. Hepatotoxicity was defined as an increase of more than three times the upper limit of normal in serum alanine aminotransferase levels after treatment. NAT2 genotypes were identified by sequencing, whereas CYP2E1 alleles were detected using polymerase chain reaction based methods. RESULTS: Of the 270 individuals included in the study, 18 (6.7%) developed drug-related hepatotoxicity. A high association was found between slow acetylators and hepatotoxicity, particularly with regard to allele *5. The adjusted risk of developing hepatotoxicity was significant in individuals carrying two slow acetylation alleles (P = 0.036, OR 3.05, 95%CI 1.07-8.64). In all of the CYP2E1 markers examined, wild homozygous genotypes were more prevalent in subjects with hepatotoxicity than in controls; however, the difference was not statistically significant. Joint evaluation of the genes revealed a high risk of developing hepatotoxicity in slow acetylators with CYP2E1 wild alleles (adjusted OR 4.26; 95%CI 1.47-12.37, P = 0.008). CONCLUSIONS: Large-scale screening for NAT2 and CYP2E1 genotypes can prove useful in predicting the risk of adverse effects.

Microsatellite markers for the Amazon peacock bass (Cichla piquiti).

A set of primers to amplify 10 microsatellite DNA loci was developed for the Neotropical fish Cichla piquiti, one of the largest sized cichlids in the Amazon Basin. These loci were used to genotype individuals from two populations, one native population from the Tocantins River, the other an introduced population in southeast Brazil, Upper Paraná River. Cross-amplification was also successful for another species of peacock bass, C. kelberi. An average of 4.4 alleles per locus (2-9 alleles) was detected. These markers will be useful for the characterization of genetic structure of native populations, and also for invasive biology studies since Cichla species have been introduced in many river basins outside their native ranges.

Effect of treadmill gait on bone markers and bone mineral density of quadriplegic subjects.

Quadriplegic subjects present extensive muscle mass paralysis which is responsible for the dramatic decrease in bone mass, increasing the risk of bone fractures. There has been much effort to find an efficient treatment to prevent or reverse this significant bone loss. We used 21 male subjects, mean age 31.95 +/- 8.01 years, with chronic quadriplegia, between C4 and C8, to evaluate the effect of treadmill gait training using neuromuscular electrical stimulation, with 30-50% weight relief, on bone mass, comparing individual dual-energy X-ray absorptiometry responses and biochemical markers of bone metabolism. Subjects were divided into gait (N = 11) and control (N = 10) groups. The gait group underwent gait training for 6 months, twice a week, for 20 min, while the control group did not perform gait. Bone mineral density (BMD) of lumbar spine, femoral neck, trochanteric area, and total femur, and biochemical markers (osteocalcin, bone alkaline phosphatase, pyridinoline, and deoxypyridinoline) were measured at the beginning of the study and 6 months later. In the gait group, 81.8% of the subjects presented a significant increase in bone formation and 66.7% also presented a significant decrease of bone resorption markers, whereas 30% of the controls did not present any change in markers and 20% presented an increase in bone formation. Marker results did not always agree with BMD data. Indeed, many individuals with increased bone formation presented a decrease in BMD. Most individuals in the gait group presented an increase in bone formation markers and a decrease in bone resorption markers, suggesting that gait training, even with 30-50% body weight support, was efficient in improving the bone mass of chronic quadriplegics.

Effect of treadmill gait on bone markers and bone mineral density of quadriplegic subjects

Quadriplegic subjects present extensive muscle mass paralysis which is responsible for the dramatic decrease in bone mass, increasing the risk of bone fractures. There has been much effort to find an efficient treatment to prevent or reverse this significant bone loss. We used 21 male subjects, mean age 31.95 ± 8.01 years, with chronic quadriplegia, between C4 and C8, to evaluate the effect of treadmill gait training using neuromuscular electrical stimulation, with 30-50 percent weight relief, on bone mass, comparing individual dual-energy X-ray absorptiometry responses and biochemical markers of bone metabolism. Subjects were divided into gait (N = 11) and control (N = 10) groups. The gait group underwent gait training for 6 months, twice a week, for 20 min, while the control group did not perform gait. Bone mineral density (BMD) of lumbar spine, femoral neck, trochanteric area, and total femur, and biochemical markers (osteocalcin, bone alkaline phosphatase, pyridinoline, and deoxypyridinoline) were measured at the beginning of the study and 6 months later. In the gait group, 81.8 percent of the subjects presented a significant increase in bone formation and 66.7 percent also presented a significant decrease of bone resorption markers, whereas 30 percent of the controls did not present any change in markers and 20 percent presented an increase in bone formation. Marker results did not always agree with BMD data. Indeed, many individuals with increased bone formation presented a decrease in BMD. Most individuals in the gait group presented an increase in bone formation markers and a decrease in bone resorption markers, suggesting that gait training, even with 30-50 percent body weight support, was efficient in improving the bone mass of chronic quadriplegics.

Response of the arterial blood pressure of quadriplegic patients to treadmill gait training.

Blood pressure pattern was analyzed in 12 complete quadriplegics with chronic lesions after three months of treadmill gait training. Before training, blood pressure values were obtained at rest, during treadmill walking and during the recovery phase. Gait training was performed for 20 min twice a week for three months. Treadmill gait was achieved using neuromuscular electrical stimulation, assisted by partial body weight relief (30-50%). After training, blood pressure was evaluated at rest, during gait and during recovery phase. Before and after training, mean systolic blood pressures and heart rates increased significantly during gait compared to rest (94.16 +/- 5.15 to 105 +/- 5.22 mmHg and 74.27 +/- 10.09 to 106.23 +/- 17.31 bpm, respectively), and blood pressure decreased significantly in the recovery phase (86.66 +/- 9.84 and 57.5 +/- 8.66 mmHg, respectively). After three months of training, systolic blood pressure became higher at rest (94.16 +/- 5.15 mmHg before training and 100 +/- 8.52 mmHg after training; P < 0.05) and during gait exercise (105 +/- 5.22 mmHg before and 110 +/- 7.38 mmHg after training; P < 0.05) when compared to the initial values, with no changes in heart rate. No changes occurred in blood pressure during the recovery phase, with the lower values being maintained. A drop in systolic pressure from 105 +/- 5.22 to 86.66 +/- 9.84 mmHg before training and from 110 +/- 7.38 to 90 +/- 7.38 mmHg after training was noticed immediately after exercise, thus resulting in hypotensive symptoms when chronic quadriplegics reach the sitting position from the upright position.

Response of the arterial blood pressure of quadriplegic patients to treadmill gait training

Blood pressure pattern was analyzed in 12 complete quadriplegics with chronic lesions after three months of treadmill gait training. Before training, blood pressure values were obtained at rest, during treadmill walking and during the recovery phase. Gait training was performed for 20 min twice a week for three months. Treadmill gait was achieved using neuromuscular electrical stimulation, assisted by partial body weight relief (30-50 percent). After training, blood pressure was evaluated at rest, during gait and during recovery phase. Before and after training, mean systolic blood pressures and heart rates increased significantly during gait compared to rest (94.16 ± 5.15 to 105 ± 5.22 mmHg and 74.27 ± 10.09 to 106.23 ± 17.31 bpm, respectively), and blood pressure decreased significantly in the recovery phase (86.66 ± 9.84 and 57.5 ± 8.66 mmHg, respectively). After three months of training, systolic blood pressure became higher at rest (94.16 ± 5.15 mmHg before training and 100 ± 8.52 mmHg after training; P < 0.05) and during gait exercise (105 ± 5.22 mmHg before and 110 ± 7.38 mmHg after training; P < 0.05) when compared to the initial values, with no changes in heart rate. No changes occurred in blood pressure during the recovery phase, with the lower values being maintained. A drop in systolic pressure from 105 ± 5.22 to 86.66 ± 9.84 mmHg before training and from 110 ± 7.38 to 90 ± 7.38 mmHg after training was noticed immediately after exercise, thus resulting in hypotensive symptoms when chronic quadriplegics reach the sitting position from the upright position.

Energy expenditure during rest and treadmill gait training in quadriplegic subjects.

STUDY DESIGN: The analysis of oxygen uptake (VO(2)) and energy consumption in quadriplegics after 6 months of treadmill gait with neuromuscular electrical stimulation (NMES). OBJECTIVES: To compare metabolic responses in quadriplegics after 6 months of treadmill training, with NMES (30-50% body weight relief), with quadriplegics who did not perform gait. SETTING: Ambulatory of University Hospital, Brazil. METHODS: Quadriplegics were separated into gait and control groups (CGs). On inclusion, all subjects performed VO(2) test. In the gait group (GG) (n=11), the protocol consisted of 8 min of rest, 10 min of treadmill walking using NMES and 10 min of recovery. In the CG (n=10), testing consisted of 8 min rest, 15 min of quadriceps endurance exercise in sitting position with NMES and 10 min recovery. VO(2), carbon dioxide production (VCO(2)) and energy consumption were measured. The GG performed 6 months of treadmill training, using NMES, for 20 min, twice a week. The CG did not practice any activity with NMES, performing conventional physiotherapy only; the CG was stimulated only during the cardiorespiratory test. RESULTS: All parameters increased significantly for the GG: 36% for VO(2) (l/min), 43% for VCO(2) (l/min) and 32.5% for energy consumption (J/kg/s). For the CG, during knee extension exercise, VO(2) increased without changes in the energy consumption (P<0.05); smaller values were obtained for all parameters when compared to those obtained during gait. CONCLUSIONS: Quadriplegic gait was efficient towards increasing VO(2) and energy consumption, which can decrease the risk of cardiovascular diseases.

Probing the binding of the coumarin drugs using peptide fragments of DNA gyrase B protein.

Bacterial DNA gyrase, has been identified as the target of several antibacterial agents, including the coumarin drugs. The coumarins inhibit the gyrase action by competitive binding to the ATP-binding site of DNA gyrase B (GyrB) protein. The high in vitro inhibitory potency of coumarins against DNA gyrase reactions has raised interest in studies on coumarin-gyrase interactions. In this context, a series of low-molecular weight peptides, including the coumarin resistance-determining region of subunit B of Escherichia coli gyrase, has been designed and synthesized. The first peptide model was built using the natural fragment 131-146 of GyrB and was able to bind to novobiocin (K(a) = 1.8 +/- 0.2 x 10(5)/m) and ATP (K(a) = 1.9 +/- 0.4 x 10(3)/m). To build the other sequences, changes in the Arg(136) residue were introduced so that the binding to the drug was progressively reduced with the hydrophobicity of this residue (K(a) = 1.3 +/- 0.1 x 10(5)/m and 1.0 +/- 0.2 x 10(5)/m for Ser and His, respectively). No binding was observed for the change Arg(136) to Leu. In contrast, the binding to ATP was not altered, independently of the changes promoted. On the contrary, for peptide-coumarin and peptide-ATP complexes, Mg(2+) appears to modulate the binding process. Our results demonstrate the crucial role of Arg(136) residue for the stability of coumarin-gyrase complex as well as suggest a different binding site for ATP and in both cases the interactions are mediated by magnesium ions.

Metabolic and cardiorespiratory responses of tetraplegic subjects during treadmill walking using neuromuscular electrical stimulation and partial body weight support.

STUDY DESIGN: Determination of differences in the cardiorespiratory responses of tetraplegic subjects with incomplete and complete lesions during treadmill gait and endurance exercise provided by neuromuscular electrical stimulation (NMES). Differences between rest and exercise phases were also examined. OBJECTIVES: To compare the cardiorespiratory responses in tetraplegic individuals during endurance exercise in the sitting position and treadmill gait with 30-50% body weight relief, both provided by NMES. SETTING: Rehabilitation Ambulatory at University Hospital, Brazil. METHODS: A total of 31 tetraplegic subjects were evaluated. Individuals were separated into two groups: gait group and endurance exercise group. In the gait group (n=17), the exercise protocol consisted of three different phases: 8 min of rest, 10 min of treadmill walking using NMES and 10 min of recovery. In the endurance exercise group (n=14), the cardiorespiratory test consisted of 8 min of rest, 15 min of quadriceps endurance exercise in the sitting position by NMES and 10 min of recovery. Oxygen uptake (VO(2)), carbon dioxide production (VCO(2)), respiratory exchange ratio (RER), pulmonary ventilation (V(E)) and heart rate (HR) were measured. RESULTS: All parameters increased considerably in the gait group from rest to the walking phase, although individuals with incomplete lesions presented a more pronounced increase than those with complete lesion. In the gait group, for incomplete tetraplegics, the mean VO(2) peak was 0.816+/-0.314 l/min, corresponding to 11.41+/-3.11 ml/kg/min; the mean value for VCO(2) was 0.660+/-0.24 l/min, mean HR was 124.54+/-28.72 bpm and mean V(E) was 28.38+/-6.28 l/min. In the endurance exercise group, for incomplete tetraplegics, the mean VO(2) peak was 0.246+/-0.07 l/min, corresponding to 3.84+/-0.92 ml/kg/min; the mean value for VCO(2) was 0.205+/-0.06 l/min, mean HR was 71.45+/-15.51 bpm and mean V(E) was 11.83+/-2.72 l/min. In the endurance exercise group, smaller differences were observed in all variables from rest to the exercise phase, compared with the large increases observed in the gait group. CONCLUSIONS: These preliminary results have shown that gait training probably improves physical capacity in tetraplegic individuals more than the endurance exercise.

Molecular cloning and characterization of Phoneutria nigriventer toxins active on calcium channels.

The aim of the present study was the molecular cloning of toxins active on calcium channels expressed by the spider Phoneutria nigriventer. Clones encoding the toxins Pn3-3A, Pn3-4A, Tx3-5, Pn3-5A, Tx3-6, Pn3-6A and Pn3-6B were identified from a cDNA library derived from the venom gland of this spider, revealing toxins of 49, 76, 45, 39, 55 and 58 amino acids residues, respectively, with polypeptide precursors being composed of three major portions: a signal peptide, a propeptide and finally, the mature toxin. A high degree of homology with the amino acid sequence was found between Pn3-3A and the neurotoxin Tx3-3 (identity of 79%), and between Pn3-4A and the neurotoxin Tx3-4 (identity of 95%). The deduced amino acid sequence for the mature polypeptides Tx3-5 and Tx3-6 confirms the polypeptide sequence previously published for these neurotoxins. In addition, the toxin Pn3-5A showed 58% identity to the Tx3-5 amino acid sequence, and the toxins Pn3-6A and Pn3-6B showed 85 and 33% identity, respectively, to the Tx3-6 amino acid sequence.

Tc-99m MDP uptake in uterine leiomyoma.

A 47-year-old woman with adenocarcinoma of the right breast had bone scintigraphy with Tc-99m MDP. Bone imaging did not show any metastases. However, a large area of increased tracer uptake was seen extending from the abdomen to the pelvis. Abdominal ultrasound revealed a large solid and heterogeneous mass, measuring 18 x 11 x 14.3 cm, that originated in an empty uterus. A biopsy of the surgical specimen showed a leiomyoma of the uterus.