Molecular epidemiology of Mycobacterium tuberculosis in China: a nationwide random survey in 2000

OBJECTIVE

To determine the contribution of the Mycobacterium tuberculosis (TB) Beijing genotype to the population structure of M. tuberculosis complex in China.

DESIGN

Genotypes of 441 mycobacterial isolates were determined by spoligotyping and IS6110 restriction fragment length polymorphism (RFLP). The isolates were from a nationwide random survey for the epidemiology of TB conducted in 2000, and the drug susceptibility patterns and epidemiological data were known.

RESULT

A total of 408 samples contained M. tuberculosis as determined by spoligotyping. Of the M. tuberculosis strains, 64.9% (265/408) were of the Beijing genotype. Using the chi-squared test, no statistically significant differences were observed in the proportion of Beijing genotype TB in patients of different sex, age or living in different areas of the country, but a significant difference was observed with multidrug-resistant (MDR) TB: 77.8% (42/ 54) of MDR isolates were of the Beijing genotype vs. 60.2% (213/354) of the drug-susceptible isolates. In the multivariate logistic regression model, the Beijing genotype was significantly associated with region and not with MDR.

CONCLUSION

The M. tuberculosis Beijing genotype has prevailed in China for at least five decades and is associated with region.

Dynamic modeling of photothermal interactions for laser-induced interstitial thermotherapy: parameter sensitivity analysis

A two-dimensional model was developed to model the effects of dynamic changes in the physical properties on tissue temperature and damage to simulate laser-induced interstitial thermotherapy (LITT) treatment procedures with temperature monitoring. A modified Monte Carlo method was used to simulate photon transport in the tissue in the non-uniform optical property field with the finite volume method used to solve the Pennes bioheat equation to calculate the temperature distribution and the Arrhenius equation used to predict the thermal damage extent. The laser light transport and the heat transfer as well as the damage accumulation were calculated iteratively at each time step. The influences of different laser sources, different applicator sizes, and different irradiation modes on the final damage volume were analyzed to optimize the LITT treatment. The numerical results showed that damage volume was the smallest for the 1,064-nm laser, with much larger, similar damage volumes for the 980- and 850-nm lasers at normal blood perfusion rates. The damage volume was the largest for the 1,064-nm laser with significantly smaller, similar damage volumes for the 980- and 850-nm lasers with temporally interrupted blood perfusion. The numerical results also showed that the variations in applicator sizes, laser powers, heating durations and temperature monitoring ranges significantly affected the shapes and sizes of the thermal damage zones. The shapes and sizes of the thermal damage zones can be optimized by selecting different applicator sizes, laser powers, heating duration times, temperature monitoring ranges, etc.

Effects of dynamic changes of tissue properties during laser-induced interstitial thermotherapy (LITT)

A two-dimensional model including the effects of dynamic changes in the physical properties on tissue temperature and damage was developed to describe laser energy transport, heat transfer, and damage accumulation during laser-induced interstitial thermotherapy (LITT). The Monte Carlo method was used to simulate photon transport in a tissue in the nonuniform optical property field, with the finite difference method used to solve the Pennes bioheat equation to calculate the temperature distribution and the Arrhenius equation used to predict the extent of thermal damage. The numerical results showed that the dynamic changes in the optical properties, thermal properties, and blood perfusion rate significantly affected damage volume accumulation and temperature history and should be included in numerical simulations of the LITT treatment.

TEM study of the structural dependence of the epitaxial passive oxide films on crystal facets in polyhedral nanoparticles of chromium

Nanocubes and partially truncated rhombic dodecahedral nanoparticles of Cr have been studied by electron diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. It is found that the nanoparticles of Cr are enclosed by the epitaxial passive oxide films. The oxide films on 100% truncated nanocubes of Cr with only one kind of facets, (100) facets, are face-centered cubic (fcc) structured Cr(2)O(3) with a lattice constant of 0.407nm. There are two kinds of oxide films in partially truncated nanoparticles of Cr with two kinds of crystallographic facets, (100) and (110). The same fcc Cr(2)O(3) is found on the (100) facets while the rhombohedral [Formula: see text] -Cr(2)O(3) is found on the (110) facets. This is similar to the two kinds of oxides, fcc and rhombohedral Fe(2)O(3), which have also been observed in polyhedral nanoparticles of Fe. These passive Cr(2)O(3), found in nanoparticles of Cr which have remained unchanged in water for four years, may have important implications for protective oxide films involving Cr.

Two-layer simulation model of laser-induced interstitial thermo-therapy

A two-layer model using different properties for the pathological tissue and the normal tissue was developed to describe the spatial photon, temperature and thermal damage distributions during laser-induced interstitial thermo-therapy (LITT). The photon distribution was simulated using the Monte Carlo method. The optical tissue parameters and the blood perfusion were derived based on the Arrhenius rate process formulation of thermal damage and kinetics of vasodilatation. The corresponding temperature distribution was numerically calculated using the Pennes bio-heat equation. The calculated results showed that the two-layer model predicted different results on the temperature variation and distribution, the thermal damage distribution and the thermal damage volume etc. from the one-layer model. As a more reasonable physical model, the two-layer model can be used to optimize the therapeutic parameters for improved LITT treatments.

Effects of thermal properties and geometrical dimensions on skin burn injuries

A one-dimensional multi-layer model is presented to characterise the skin burn process resulting from the application of a high temperature heat source to a skin surface. Transient temperatures were numerically calculated using a finite difference method to solve the Pennes bioheat equation. A damage function denoting the extent of burn injury was then calculated using the Arrhenius assumptions. The model was used to predict the effects of thermal physical properties and geometrical dimensions on the transient temperature and damage function distributions. The results show that the epidermis and dermis thicknesses significantly affect the temperature and burn injury distributions, while variations of the initial temperatures and the blood perfusion have little effect.

1-D polymer containing the [Ru-N-Ru] mu-nitrido moiety: crystal structure and magnetic properties of ([Cu(en)2]3[Ru2N(CN)10].ClO4)n (en = 1,2-diaminoethane)

A novel (mu-nitrido-diruthenium)-bridged 1-D coordination polymer was formed from reaction of K5[Ru2N(CN)10] with [Cu(en)2](ClO4)2; a similar reaction with [Cu(pn)2][(ClO4)2] (pn = 1,3-diaminopropane) gave ([Cu(pn)2]5[Ru2N(CN)10]2) as a discrete molecular compound; variable temperature susceptibility measurements show that there is a weak ferromagnetic interaction between the Cu(II) ions in 1-D polymer.

Analysis of the drude model in metallic films

A method, believed to be new, to simulate Drude parameters for collective oscillation of the free carriers in metallic films is proposed. Plasma resonance frequency and relaxation were simulated simultaneously from both the real and the imaginary parts of the dielectric function of a metallic film after consideration of their correlation in the Drude model. As examples, the contributions of the electrons in Ag films and of the free carriers in metallic silicide, NbSi(2) and TaSi(2), films have been studied.

Enhancement of the sensitivity of a capillary electrophoresis immunoassay for estradiol with laser-induced fluorescence based on a fluorescein-labeled secondary antibody

A competitive immunoassay for estradiol (E2) based on capillary electrophoresis was established. This method was based on the competitive reaction of complete antigen and E2 with a limited amount of monoclonal antibody, with fluorescein isothiocyanate (FITC)-labeled secondary antibody as a fluorescence probe. The addition of the thermally reversible hydrogel, poly-N-isopropylacrylamide (pNIPA) in the buffer as a replaceable packing material improved reproducibility and resolution of the method. This capillary electrophoresis immunoassay with laser-induced fluorescence can be applied to determine E2 with good precision at concentrations as low as 9 pg/mL. Details of typical separations of immunological complex and free reactants are presented.

Anisotropic magnetocaloric effect in nanostructured magnetic clusters

We report the first experimental observation of anisotropic magnetocaloric effect (MCE) in the Fe8 clusters. It is found that the magnetic anisotropy plays a very important role in the determination of the magnetocaloric effect. The maximum and minimum MCE's are observed when the applied magnetic fields are parallel and perpendicular to the easy axis, respectively. The quantum spin Hamiltonian of a Fe8 cluster is used to calculate the partition function and the magnetization in a range of temperature and magnetic field. Excellent quantitative agreement between the experimental data and calculation is observed.

Renal ischemia enhances electrical activity and Fos protein expression of the rostral ventrolateral medullary neurons in rats

The effects of renal ischemia on spontaneous electrical activity and Fos protein expression of nucleus paragigantocellularis lateralis (PGL) in rostral ventrolateral medulla (RVLM) were observed in 67 anesthetized Sprague-Dawley rats with sinoaortic denervation by using extracellular recording and immunohistochemical techniques. The results obtained are as follows. (1) Renal ischemia increased the discharge rate from 11.40 +/- 1.08 to 21.1 +/- 1.74 spikes/s (P < 0.001) in 28 out of 30 PGL neurons, while blood pressure and heart rate had no significant change (P > 0.05). (2) Administration of 8-phenyltheophylline (8-PT), an adenosine receptor antagonist, did not affect the discharge rate of PGL neurons, but could partially inhibit the effects of renal ischemia in 17 units (P < 0.05). (3) Renal ischemia resulted in a remarkable increase in the number of Fos-like protein immunoreactive PGL neurons in the RVLM (P < 0.01). (4) Fos protein expression induced by renal ischemia was significantly inhibited by pretreatment with 8-PT (P < 0.05). Taken together, it is concluded that renal ischemia induces an increase in spontaneous electrical activity and Fos protein expression in PGL neurons of RVLM, and that adenosine released within ischemic kidney may be involved in such effects.

[Important bio-thermal physical problems and latest advancement in laser cell engineering]

The recently emerging technique of laser microsurgery (optical tweezers, optical scissors, etc.) is providing a new precise, sterile method for the cell engineering practices such as introduction of external gene into an object cell, cell-fusion, and trapping or transportation of microscopic objects (cells or chromosomes etc.). The thermal effects thus induced usually proved to be critical factors for successful operation of this method. In order to meet the requirement for the rapid development in this territory, some important bio-thermal physical problems and the corresponding research subjects in this area were comprehensively summarized. Difficulties and critical issues were discussed. The latest advancement of the laser cell engineering was also described. This review is attempted to bridge up the gap between bioengineering and thermal science fields and then to enhance the rapid progress of laser microsurgery.

Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa

A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv. viciae genotypes in the absence of its host plant.

Superconductivity in 4 angstrom single-walled carbon nanotubes

Investigation of the magnetic and transport properties of single-walled small-diameter carbon nanotubes embedded in a zeolite matrix revealed that at temperatures below 20 kelvin, 4 angstrom tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation supercurrent. The measured superconducting characteristics display smooth temperature variations owing to one-dimensional fluctuations, with a mean-field superconducting transition temperature of 15 kelvin. Statistical mechanic calculations based on the Ginzburg-Landau free-energy functional yield predictions that are in excellent agreement with the experiments.

Giant Hall effect in nonmagnetic granular metal films

Nearly 3 orders of magnitude enhancement in the Hall coefficient is observed in Cu(x)-(SiO(2))(1--x) granular films. This large enhancement of the Hall coefficient not only is significantly larger than the prediction of the classical percolation theory, but also occurs at a metal concentration identified to be the quantum percolation threshold. Measurements of the electron dephasing length and magnetoresistance, plus the TEM characterization of microstructures, yield a physical picture consistent with the mechanism of the local quantum interference effect.

[Analysis of isozyme and RAPD for the germplasm lines from G. hirsutum x G. bickii]

To study the effectiveness of Gossypium interspecific hybrid breeding on molecular level, the six germplasm lines from interspecific hybrids between G. hirsutum and G. bickii were analysed by the techniques of RAPD and isozyme electrophoresis. The main results were summarized as follows: (1) The basic zymograms of peroxidase isozyme of the six germplasm lines were similar to their G. hirsutum parent, but two out of the germplasm lines showed one specific band of the wild parent of G. bickii (pI 4.85); (2) The RAPD fingerprint showed distinct difference of genomic DNA among the germplasm lines; (3) The four specific DNA fragments of G. bickii were observed in RAPD patters of four out of the six germplasm lines.

[A study of genetic character of cultivar Shiyuan 321 from G. barbadense x G. thurberi x G. hirsutum using isozyme and RAPD techniques]

To study the genetic character of trispecific hybrid cultivar Shiyuan 321, we analyzed this cultivar and its parents by isozyme and RAPD techniques. The main results are as follows: (1) Esterase isozyme analysis showed that there was one specific band among cultivar Suiyuan 321 and its parents, G. thurberi and G. barbadense; (2) Six specific DNA fragments amplified by 4 primers were found among cultivar Shiyuan 321 and its parents G. barbadense, G. thurberi; (3) By comparing RAPD differences among Shiyuan 321 and its parents, it is indicated that the genetic heterogeneity of cultivar Shiyuan 321 is very high at its genomic DNA level. The above results proved that Shiyuan 321 is a trispecific cultivar from G. barbadense x G. thurberi x G. hirsutum as well as a new germplasm.

Dynamic modulation of NMDA-induced responses by ifenprodil in rat prefrontal cortex

Ifenprodil is known to inhibit channel opening of NMDA receptors containing the NR2B subunit. However, it has also been shown to increase NMDA receptor affinity for glutamate-site agonists, including NMDA. The coexistence of the two opposing effects may explain why ifenprodil can either enhance or suppress an NMDA response depending on the level of NMDA binding and thus the NMDA concentration. Using whole cell recordings in rat prefrontal cortical slices, we report here that the effect of ifenprodil also depends on the speed and the direction of change of NMDA concentration. As shown previously, ifenprodil increased the inward current induced by low concentrations of NMDA applied through a local Y-tube perfusion system. However, the rising phase of the current was less enhanced compared to the falling phase. Increasing the speed of rising of NMDA concentration further reduced the enhancing effect of ifenprodil. When pressure ejection was used to produce even faster NMDA responses, the entire rising phase including the peak of the response was suppressed by ifenprodil, while the falling phase remained enhanced. These results are consistent with the suggestion that ifenprodil decreases both the association and dissociation rates of NMDA from NMDA receptors, and suggest that ifenprodil affects slow and fast NMDA responses in different manners. In particular, this study suggests that ifenprodil inhibits the rising phase of a fast NMDA response by suppressing both channel opening and the association of NMDA with NMDA receptors and that this inhibition can occur even when the level of NMDA binding is low.

Symbiotic plasmid rearrangement in Rhizobium leguminosarum bv. viciae VF39SM

A rearrangement between the symbiotic plasmid (pRleVF39d) and a nonsymbiotic plasmid (pRleVF39b) in Rhizobium leguminosarum bv. viciae VF39 was observed. The rearranged derivative showed the same plasmid profile as its parent strain, but hybridization to nod, fix, and nif genes indicated that most of the symbiotic genes were now present on a plasmid corresponding in size to pRleVF39b instead of pRleVF39d. On the other hand, some DNA fragments originating from pRleVF39b now hybridized to the plasmid band at the position of pRleVF39d. These results suggest that a reciprocal but unequal DNA exchange between the two plasmids had occurred.

[Genetic analysis for introgressive genes of petal color from Gossypium bickii to G. hirsutum L]

The character of red petals with a large basal spot was transferred from Gossypium bickii into G. hirsutum L., and the pure lines (HBRL) with the character were obtained by Liang Zhenglan in 1988. Results of genetic analysis for G. hirsutum pure line of red petals (R3bic) and large basal spot (R2bic) were reported in the present study. The large basal spot was dominant to the small basal-spot and spotlessness of G. hirsutum. R2bic was shown to be allelic to R2 of G. hirsutum, and R2bic, R2 and r2 were multiple alleles. R2bic was found to be linked with Lc1, and linkage between R2bic and Lc1 was estimated at 37.31 +/- 2.44 centimorgans, The red petal (R3bic) was epistatic dominance to the yellow petal (Y1) and cream petal (y1), and R3bic is closely linked with R2bic. It is proposed that the introgressive gene of the large basal spot from G. bickii into G. hirsutum be assigned gene symbol R2bic, and the red petals be given the gene symbol R3bic.

[NADPH-diaphorase activity and Fos expression in brainstem nuclei involved in cardiovascular regulation following intracarotid injection of capsaicin]

The present study was undertaken to define whether intracarotid injection of capsaicin induces Fos expression associated with the activation of NOS-containing neurons in brainstem nuclei by combining the immunocytochemical method for Fos with NADPH-d histochemical technique for NOS. The results obtained are as follows: (1) Intracarotid injection of capsaicin caused a significant increase of Fos-like immunoreactive neurons in area postrema (AP), nucleus tractus solitarius (NTS), paragigantocellularis lateralis (PGL) and locus coeruleus (LC), without influence upon the neurons of raphe nuclei (RN) and periaqueductal gray (PAG). (2) NO-containing neurons in PGL and NTS and the double-labeled neurons in PGL were also increased significantly following intracarotid injection of capsaicin. Small numbers of NO-containing neurons were found in LC, but there was no change in the number of NO-containing neurons in RN and PAG. No NADPH-d histochemical activity could be found in AP. (3) The above responses to capsaicin were significantly inhibited by pretreatment with either a capsaicin receptor antagonist ruthenium red or a NMDA receptor antagonist MK-801. The above results indicate that intracarotid injection of capsaicin may activate the neurons in brainstem nuclei involved in cardiovascular regulation, and that NO only plays an indirect role in the modulation of the responses of brainstem nuclei to capsaicin. These effects of capsaicin are mediated by capsaicin receptors with involvement of glutamate.