A theoretical approach to the photochemical activation of matrix isolated aluminum atoms and their reaction with methane.

The photochemical activation of Al atoms in cryogenic matrices to induce their reaction with methane has been experimentally studied before. Here, a theoretical study of the nonadiabatic transition probabilities for the ground ((2)P:3s(2)3p(1)) and the lowest excited states ((2)S:3s(2)4s(1) and (2)D:3s(2)3d(1)) of an aluminum atom interacting with a methane molecule (CH(4)) was carried out through ab initio Hartree-Fock self-consistent field calculations. This was followed by a multiconfigurational study of the correlation energy obtained by extensive variational and perturbational configuration interaction analyses using the CIPSI program. The (2)D state is readily inserted into a C-H bond, this being a prelude to a sequence of avoided crossings with the initially repulsive (to CH(4)) lower lying states (2)P and (2)S. We then use a direct extension of the Landau-Zener theory to obtain transition probabilities at each avoided crossing, allowing the formation of an HAlCH(3) intermediate that eventually leads to the final pair of products H+AlCH(3) and HAl+CH(3).

Transition probabilities for the Au ((2)S, (2)D, and (2)P) with SiH(4) reaction.

Transition probabilities on the interaction of the ground and the lowest excited states of gold Au ((2)S:5d(10)6s(1), (2)D:5d(9)6s(2), and (2)P:5d(10)6p(1)) with silane (SiH(4)) are studied through ab initio Hartree-Fock self-consistent field calculations, where the atom's core is represented by relativistic effective core potentials. These calculations are followed by a multiconfigurational self-consistent field study. The correlation energy is accounted for through extensive variational and perturbative second order multireference Moller-Plesset configuration interaction analysis of selected perturbations obtained by iterative process calculations using the CIPSI program package. It is found that the Au atom in the ((2)P:5d(10)6p(1)) state inserts in the Si-H bond. In this interaction its corresponding D (2)A(') potential energy surface is initially attractive and only becomes repulsive after encountering an avoided crossing with the initially repulsive C (2)A(') surface linked to the Au((2)D:5d(9)6s(2))-SiH(4) fragments. The A, B, and C (2)A(') curves derived from the Au((2)D:5d(9)6s(2)) atom interaction with silane are initially repulsive, each one of them showing two avoided crossings, while the A (2)A(') curve goes sharply downwards until it meets the X (2)A(') curve interacting adiabatically, which is linked with the Au((2)S:5d(10)6s(1))-SiH(4) moieties. The A (2)A(') curve becomes repulsive after the avoided crossing with the X (2)A('), curve. The lowest-lying X (2)A(') potential leads to the HAuSiH(3) X (2)A(') intermediate molecule. This intermediate molecule, diabatically correlated with the Au((2)P:5d(10)6p(1))+SiH(4) system which lies 3.34 kcal/mol above the ground state reactants, has been carefully characterized as have the dissociation channels leading to the AuH+SiH(3) and H+AuSiH(3) products. These products are reached from the HAuSiH(3) intermediate without any activation barrier. The Au-SiH(4) calculation results are successfully compared to experiment. Landau-Zener theory of avoided crossings is applied to these interactions considering the angle theta instead of the distance r as the reaction coordinate.

[Tumor necrosis factor as a biomarker of infection in total knee arthroplasty]. / El factor de necrosis tumoral alpha como biomarcador de infección en las artroplastias totales de rodilla.

BACKGROUND: Thanks to defense mechanisms, organisms have had to adapt themselves to an adverse natural setting that causes acute and chronic stress. This adaptive response that tries to protect the cells against lethal insults uses its own defense systems. MATERIAL AND METHODS: Prospective, observational, descriptive pilot study with analytic components to determine the baseline preoperative TNF levels of 35 patients undergoing total knee arthroplasty due to gonarthrosis. Ten patients with a diagnosis of infected total knee arthroplasty were also included. In order to find differences and possible associations, the Mann-Whitney U test or the Fisher test was used to compare the variables between the non-infected group of patients and the group with the infection complication. RESULTS: We found a statistically significant difference; higher levels of fibrinogen, erythrocyte sedimentation rate, C-reactive protein, TNF-alpha and temperature were found in the infected patients; temperature was not clinically relevant. CONCLUSIONS: In the absence of a diagnostic specificity, the combined determinations of acute phase reactants may be useful to detect the presence and intensity of the inflammatory and infectious processes.

Magnetoviscosity of dilute suspensions of magnetic ellipsoids obtained through rotational Brownian dynamics simulations.

The magnetic field dependent viscosity (magnetoviscosity) of dilute suspensions of magnetic tri-axial ellipsoidal particles suspended in a Newtonian fluid and under applied shear and magnetic fields was studied numerically. Brownian dynamics simulations were performed to compute the intrinsic magnetoviscosity of the suspension. Results are presented for the response of dilute suspensions of ellipsoidal particles to constant magnetic and shear flow fields. Suspensions of ellipsoidal particles show a significant effect of aspect ratio on the intrinsic magnetoviscosity of the suspension, and this effect is more pronounced as the aspect ratio becomes more extreme. The use of an effective rotational diffusion coefficient D(r,eff) collapses the normalized intrinsic magnetoviscosity of all suspensions to a master curve as a function of Péclet number with the Langevin parameter alpha=(mu(0)muH)/(k(B)T) as parameter, up to a critical value of alpha for which the results for suspensions of spherical particles deviate from those of suspensions of ellipsoids. This discrepancy is attributed to the action of the shear-torque on the ellipsoidal particles, which tends to orient these particles in the direction of maximum deformation of the simple shear flow, and which does not act on spherical particles.

[Complications of the direct endonasal transsphenoidal approach in the management of pituitary adenomas]. / Complicaciones del abordaje endonasal directo transesfenoidal en el manejo de adenomas de hipófisis.

OBJECTIVE: To describe the frequency of complications and complaints caused by direct endonasal transsphenoidal approach used in the resection of pituitary adenomas. PATIENTS AND METHODS: In a retrospective way, we review patients' records with pituitary adenomas, operated by means of direct endonasal transsphenoidal approach, between August 2003 and December 2004. We recollected information about operative and postoperative complications, besides complaints registered in patients' records. RESULTS: 41 patients were included, 23 (56.1%) males and 18 (43.9%) females, with a mean age of 47.7 -/+16.8 years. Operative complications were intrasellar hemorrhage in three patients (7.3%), hypertension in two (4.9%) and cerebrospinal fluid fistula in one (2.4%). On the other hand, postoperative complications were diabetes insipidus (24.4%) in ten cases, anterior pituitary insufficiency (4.9%) in two and sinusitis (2.4%) in one. Nasal congestion was the most common complaint (31.7%) in thirteen patients. CONCLUSIONS: Supported in our results, the direct endonasal transsphenoidal approach tends to present mainly fewer nasal complications and complaints, and in the future it could be considered like the preferred approach for resection of pituitary adenomas.

Ab initio study of the reactions of Ga((2)P, (2)S, and (2)P) with silane.

The interactions of Ga((2)P:4s(2)4p(1), (2)S:4s(2)5s(1), and (2)P:4s(2)5p(1)) with SiH(4) are studied by means of Hartree-Fock self-consistent field (SCF) and multiconfigurational SCF followed by extensive variational and perturbational second-order multireference Møller-Plesset configuration by perturbation selected by iterative process calculations, using relativistic effective core potentials. The Ga atom in its (2)P(4s(2)5p(1)) state can spontaneously insert into the SiH(4). The Ga atom in its (2)S(4s(2)5s(1)) state is inserted into the SiH(4). In this interaction the 3 (2)A(') potential energy surface initially attractive becomes repulsive after meeting the 2 (2)A(') surface linked with the Ga((2)P:4s(2)4p(1))+SiH(4) fragments. The two (2)A(') curves (2 (2)A(') and X (2)A(')) derived from the interaction of Ga((2)P:4s(2)4p(1)) atom with silane molecule are initially repulsive. The 2 (2)A(') curve after an avoided crossing with the 3 (2)A(') curve goes down until it meets the X (2)A(') curve. The 2 (2)A(') curve becomes repulsive after the avoided crossing with the X (2)A(') curve. The X (2)A(') curve becomes attractive only after its avoided crossing with the 2 (2)A(') curve. The lowest-lying X (2)A(') potential leads to the HGaSiH(3)X (2)A(') intermediate molecule. This intermediate molecule, diabatically correlated with the Ga((2)S:4s(2)5s(1))+SiH(4) fragments, which lies 1.5 kcal/mol above the ground state reactants leads to the GaH+SiH(3) or H+GaSiH(3) products through the dissociation channels. These products are reached from the HGaSiH(3) intermediate without activation barriers. This work shows that the Ga atom at its first excited state in the presence of silane molecules in gas phase leads to the formation of SiH(3) radicals, H atoms, GaH hydrides, as well as gallium silicide molecules.

Ab initio study of the reactions of Ga(2P, 2S, and 2P) with methane.

The interactions of Ga(2P:4s(2)4p1, 2S:4s(2)5s1, and 2P:4s(2)5p1) with CH4 is studied by means of Hartree-Fock self-consistent-field (SCF) calculations using relativistic effective core potentials and multiconfigurational-SCF plus multireference variational and perturbational on second-order Möller-Plesset configuration interaction calculations. The Ga atom 2P(4s(2)5p1) state can spontaneously insert into the CH4. In this interaction the 4 2A potential energy surface is initially attractive and becomes repulsive only after meeting with the 3 2A surface, adiabatically linked with the Ga(2S:4s(2)5s1) + CH4 fragments. The Ga atom 2S(4s(2)5s1) excited state inserts in the C-H bond. In this interaction the 3 2A potential energy surface initially attractive, becomes repulsive after meet the 2 2A' surface linked with the Ga(2P:4s(2)4p1) + CH4 fragments. The two 2A curves (2 2A and X 2A) derived from the interaction of Ga(2P:4s(2)4p1) atoms with methane molecules are initially repulsive. The 2 2A curve after an avoided crossing with the 3 2A curve goes smoothly down and reaches a minimum: after this point, it shows an energy barrier. The top of this barrier is located below the energy value of the Ga(2S:4s(2)5s1) + CH4 fragments. After this energy top the 2 2A curve goes down to meet the X 2A curve. The 2 2A curve becomes repulsive after the avoided crossing with the X 2A curve. The X 2A curve becomes attractive only after its avoided crossing with the 2 2A curve. The lowest-lying X 2A potential leads to the HGaCH3 X 2A intermediate molecule. This intermediate molecule, diabatically correlated with the Ga(2S:4s(2)5s1) + CH4 fragments, which lie 6 kcal/mol, above the ground-state reactants, the dissociation channels of this intermediate molecule leading to the GaH + CH3 and H + GaCH3 products. These products are reached from the HGaCH3 intermediate without activation barriers. The work results suggest that Ga atom in the first excited state in gas-phase methane molecules could produce better quality a-C:H thin films through CH3 radicals, as well as gallium carbide materials.

A molecular phylogeny of the grass subfamily Panicoideae (Poaceae) shows multiple origins of C4 photosynthesis.

DNA sequence data from the chloroplast gene ndhF were analyzed to estimate the phylogeny of the subfamily Panicoideae, with emphasis on the tribe Paniceae. Our data suggest that the subfamily is divided into three strongly supported clades, corresponding to groups with largely identical base chromosome numbers. Relationships among the three clades are unclear. In unweighted parsimony analyses, the two major clades with x = 10 (Andropogoneae and x = 10 Paniceae) are weakly supported as sister taxa. The third large clade corresponds to x = 9 Paniceae. In analyses under implied weight, the two clades of Paniceae are sisters, making the tribe monophyletic. Neither resolution is strongly supported.Our molecular phylogenies are not congruent with previous classifications of tribes or subtribes. Based on this sample of species, we infer that C(4) photosynthesis has evolved independently several times, although a single origin with multiple reversals and several reacquisitions is only slightly less parsimonious. The phosphoenol pyruvate carboxykinase (PCK) subtype of C(4) photosynthesis has evolved only once, as has the NAD-malic enzyme (ME) subtype; all other origins are NADP-ME. Inflorescence bristles are apparently homologous in the genera Setaria and Pennisetum, contrary to opinions of most previous authors. Some genera, such as Digitaria, Echinochloa, and Homolepis are supported as monophyletic. The large genus Paspalum is shown to be paraphyletic, with Thrasya derived from within it. As expected, Panicum is polyphyletic, with lineages derived from multiple ancestors across the tree. Panicum subg. Panicum is monophyletic. Panicum subg. Dichanthelium, subg. Agrostoides, and subg. Phanopyrum are unrelated to each other, and none is monophyletic. Only Panicum subg. Dichanthelium sect. Dichanthelium, represented by P. sabulorum and P. koolauense, is monophyletic. Panicum subg. Megathyrsus, a monotypic subgenus including only the species P. maximum, is better placed in Urochloa, as suggested by other authors.

Motor unit recruitment strategy of knee antagonist muscles in a step-wise, increasing isometric contraction.

The purpose of this study was to determine if differences exist between the control strategies of two antagonist thigh muscles during knee flexion and extension muscular coactivation. Surface myoelectric signal (MES) of the quadriceps (rectus femoris) and the hamstrings (semitendinosus) were obtained from both muscles while performing step-wise increasing contractions during flexion and extension with the knee at 1.57 rad of flexion (90 degrees). The median frequency of the power density spectrum, which is related to the average muscle fiber action potential conduction velocity and therefore to motor unit recruitment, was calculated from each MES. The results suggest that, in all the subjects tested, when the muscle acts as antagonist most motor units are recruited up to 50% of the maximal voluntary force, whereas when the muscle acts as antagonist motor units are recruited up to 40% of the maximal voluntary force. The force range past 40-50% of the maximal force is also characterized by differences between the agonist/antagonist.

Clonal variation of tumorigenic potential in v-Ha-ras-transformed human bronchial epithelial cells: relationship to ras oncogene expression and CAD gene amplification.

Infection of an SV40 large-T antigen-"immortalized" human bronchial epithelial cell line with a Zip-v-Ha-ras retroviral vector resulted in a mass culture that was tumorigenic in athymic nude mice. A tumor cell line derived from passage of the mass culture in vivo, however, exhibited increased tumorigenicity and v-Ha-ras expression. To examine and compare the molecular events involving the ras oncogene during cell transformation in vitro and subsequent tumor formation in vivo, clonal cell populations were isolated from the v-Ha-ras-transformed mass culture. While the clonal cell lines exhibited diverse tumorigenic profiles, these differences did not correlate with v-Ha-ras expression. However, the expression of the activated ras gene, while not necessary for growth in vitro, did appear to be associated with a selective growth advantage in vivo. In addition, the modulation of gene amplification ability in these cells was not associated with the induction of tumorigenicity or v-Ha-ras expression.

Control strategies of the elbow antagonist muscle pair during two types of increasing isometric contractions.

The purpose of this study was to determine if differences exist between the control strategies of the elbow flexor and extensor muscles performing stepwise and linearly increasing isometric contractions, and to determine their control strategy when active as antagonists to each other. The electromyogram (EMG) from the biceps brachii and triceps brachii were recorded during stepwise and linearly increasing contractions in flexion and extension. The power density spectrum of the EMG was determined and the median frequency (MF) for each spectrum was calculated for assessment of changes in the average conduction velocity, which reflects motor unit recruitment and derecruitment, and thereby the control strategy of the muscle. The results suggest that differences exist in the control strategies employed by a single muscle during stepwise and linearly increasing contractions. Furthermore, the antagonist triceps recruits motor units up to a higher force level during stepwise contractions than during linearly increasing contractions. The antagonist biceps derecruits motor units up to a higher force level during linearly increasing contractions than during stepwise contractions.

Subpopulations of human bronchial epithelial cells in culture respond heterogeneously to 12-O-tetradecanoylphorbol-13-acetate (TPA) and other modulators of differentiation.

A greater understanding of the processes involved in the control of proliferation and differentiation should provide insight into the mechanisms involved in carcinogenesis. Studies were undertaken to examine the effects of modulators of differentiation on the proliferation, colony forming efficiency (CFE), and cross-linked envelope (CLE) formation of human bronchial epithelial (HBE) cells in culture. Treatment for 24 h with a low concentration of TPA (0.1 ng/ml) induced a 2-fold increase in CLE but little inhibition of CFE, suggesting that these two endpoints might be occurring independently of one another. Continuous culture in a low concentration of TPA (0.1 ng/ml) arrested growth in greater than 99% of the cells, but after 10-14 days, a few colonies were observed that were resistant to TPA. This TPA resistant subpopulation occurred at a frequency of less than 0.1% of the cells seeded into cultures. Short term treatment (24 h) with fetal bovine serum (FBS; 1-8%) or calcium (0.5-2 mM) resulted in 2-4 fold increases in CLE with no significant change in CFE. Continuous treatment with FBS or calcium for up to 5 days produced similar results. These findings suggest that different subpopulations of cells exist within cultures of HBE cultures, perhaps at different states of maturation, and that these subpopulations respond differently to modulators of differentiation.

Differential effects of tumour promoters on the growth of normal human bronchial epithelial cells and human lung tumour cell lines.

The effects of the tumour promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA) on the colony-forming efficiency and growth of normal human bronchial epithelial (NHBE) cells and five lung squamous carcinoma cell lines were compared in medium containing 1% foetal bovine serum. TPA (0.1-5.0 ng/ml) inhibited the growth of NHBE cells and one carcinoma cell line, while four of the five carcinoma lines were less sensitive to the growth inhibitory properties of TPA but were slightly inhibited at higher TPA concentrations. The responses of NHBE cells and carcinoma cells to TPA, and the related compounds, mezerein, 4-O-methyl TPA, and phorbol were then compared in serum-free medium. In general, the removal of serum from the medium increased the differences in the responses to TPA between normal and tumour cells. Two carcinoma lines inhibited by TPA in 1% serum were stimulated by TPA in the absence of serum. Mezerein and, to a lesser extent, 4-O-methyl TPA also produced differential responses in colony-forming efficiencies between tumour lines and NHBE cells. Phorbol had no effect on either NHBE cells or on carcinoma cell lines. The relative insensitivity of carcinoma cell lines to the growth inhibitory effects of tumour promoters is consistent with the hypothesis that tumour promotion involves selection against normal cells to permit clonal expansion of preneoplastic or neoplastic cell types.

Lack of di-(2-ethylhexyl) phthalate activity in the C3H 10T 1 2 cell transformation system.

The widely used plasticizer and rodent carcinogen di-(2-ethylhexyl) phthalate (DEHP) was examined for activity in the C3H 10T 1 2 murine fibroblast cell transformation system. Treatment with DEHP or its metabolite, mono-(2-ethylhexyl) phthalate, did not produce oncogenic transformation, initiate the process of transformation in cultures treated with a tumour promoter or promote the process of transformation in cultures pretreated with a chemical carcinogen. These findings are consistent with the suggestion that the carcinogenicity of DEHP is mediated by an indirect mechanism and not by covalent interaction of DEHP with DNA.

Reversible expression of morphological transformation in C3H/10T1/2 mouse embryo cultures exposed to 12-O-tetradecanoylphorbol-13-acetate.

Treatment of C3H/10T1/2 mouse embryo fibroblasts with N-methyl-N'-nitro-N-nitrosoguanidine and then 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in the production of numerous foci of morphologically transformed cells. When dishes containing foci were provided medium which did not contain TPA, up to 84% of the foci were found to regress. Promotion of morphological transformation by TPA in C3H/10T1/2 cells may thus be a reversible process.

Effect of mouse skin tumor promoters upon [3H]uridine exchange and focus formation in cultures of C3H/10T1/2 mouse fibroblasts.

The abilities of 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate (4-O-methyl-TPA) and mezerein to promote the process of transformation were evaluated in cultures of C3H/10T1/2 mouse embryo fibroblasts treated with N-methyl-N'-nitro-N-nitrosoguanidine. Mezerein was found to be as potent as the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) for the promotion of focus formation, eliciting a promotion response at concentrations that ranged from 100 to 2500 ng/ml. 4-O-Methyl-TPA (25-2500 ng/ml) did not promote focus formation, but was mitogenic for confluent cultures. The effects of promoting and non-promoting compounds upon intercellular communication were then evaluated to determine if a rapid assay for the inhibition of communication might serve as a surrogate for the relatively long term, labor-intensive cell transformation assay. Inhibited intercellular communication, as measured by inhibition of [3H]uridine exchange between cells, appeared to correlate with the ability of phorbol related compounds to promote transformation. However, the potent promoter 2,3,7,8-tetrachlorodibenzo-p-dioxin did not inhibit [3H]uridine transfer. Inhibition of intercellular communication may thus be diagnostic of the promoting potential of phorbol-related compounds in C3H/10T1/2 cultures, but may not be an appropriate endpoint for the study of carcinogenic dioxins.