[The meaning of serum myeloperoxidase in obstructive sleep apnea hypopnea syndrome]

Objective:To investigate the clinical significance of detecting peripheral blood myeloperoxidase in OSAHS patients. Method:Sixty cases of OSAHS patients in our hospital was selected as OSAHS group, which was subdivided into light, medium and heavy groups according to the PSG, each with 20 cases, and 20 cases of healthy persons were selected as control group; ELISA method was used to detect the MPO level of peripheral blood. 20 cases of severe OSAHS patients detect MPO level again three months after the fist detection, and analyze the correlation between serum MPO level and indicators of sleep respiratory related events. Result:①The level of peripheral serum MPO level positively correlated with the severity of the patients' condition. The control group, light, medium and heavy groups' serum MPO levels were (7.93±2.44), (10.58±3.31), (18.91±8.37), (29.03±10.06)ng/mg, respectively (F=19.102, P<0.05). ②OSAHS patients' peripheral blood MPO concentration had no correlation with gender, age and BMI, but was positively correlated with AHI and negatively correlated with LSaO₂ (P<0.05). ③Twenty cases of severe MPO and AHI patients with OSAHS were decreased and LSaO₂ increased, the difference was statistically significant (P<0.05). Conclusion:The detection of serum MPO in patients with OSAHS has important significance in judging the severity of the disease, evaluating the treatment effect and predicting the risk of cardiovascular disease in patients with severe OSAHS.

Cyclic adenosine monophosphate-protein kinase A signal pathway may be involved in pulmonary aquaporin-5 expression in ischemia/reperfusion rats following deep hypothermia cardiac arrest

We investigated the effects of cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) on the expression of aquaporin 5 (AQP5) in ischemia/reperfusion (I/R) rats following deep hypothermia cardiac arrest. Wistar rats were randomly divided into: a sham control group (subjected to a sham operation); an I/R group (subjected to occlusion of the bronchial arteries and the left inferior pulmonary artery); an H89 group (subjected to occlusion of the bronchial arteries and the left inferior pulmonary vein and artery, and treated with 5 mg/kg H89 for 2 days before the study); and a forskolin group (subjected to occlusion of the bronchial arteries and the left inferior pulmonary vein and artery, and treated with 5 mg/kg forskolin for 2 days before the study). Expression levels of AQP5 mRNA and protein were determined using reverse transcription-polymerase chain reaction and western blotting. Decreased expression of AQP5 was noted in the pulmonary tissues of the I/R group compared with the sham controls. Compared to that in the control group, there was a notable decrease in AQP5 expression in the I/R group. After treating with forskolin, AQP5 expression increased in the forskolin group compared with the I/R group. In the H89 group, AQP5 expression decreased compared with the I/R group. The decreased expression of AQP5 was possibly associated with acute pulmonary injury induced by I/R. The cAMP-PKA signal pathway may be involved in the expression of AQP5 in I/R rats after deep hypothermia cardiac arrest.

Genome-wide analysis of the GRAS gene family in physic nut (Jatropha curcas L.)

GRAS proteins play vital roles in plant growth and development. Physic nut (Jatropha curcas L.) was found to have a total of 48 GRAS family members (JcGRAS), 15 more than those found in Arabidopsis. The JcGRAS genes were divided into 12 subfamilies or 15 ancient monophyletic lineages based on the phylogenetic analysis of GRAS proteins from both flowering and lower plants. The functions of GRAS genes in 9 subfamilies have been reported previously for several plants, while the genes in the remaining 3 subfamilies were of unknown function; we named the latter families U1 to U3. No member of U3 subfamily is present in Arabidopsis and Poaceae species according to public genome sequence data. In comparison with the number of GRAS genes in Arabidopsis, more were detected in physic nut, resulting from the retention of many ancient GRAS subfamilies and the formation of tandem repeats during evolution. No evidence of recent duplication among JcGRAS genes was observed in physic nut. Based on digital gene expression data, 21 of the 48 genes exhibited differential expression in four tissues analyzed. Two members of subfamily U3 were expressed only in buds and flowers, implying that they may play specific roles. Our results provide valuable resources for future studies on the functions of GRAS proteins in physic nut.

Association of Resting Heart Rate with Infrarenal Aortic Diameter: A Cross Sectional Study in Chinese Hypertensive Adults

OBJECTIVE

Elevated resting heart rate (RHR) has been shown to be a risk marker for cardiovascular disease. Results from studies on the effects of RHR in large arteries are limited to the functional changes of those arteries, while the association between RHR and aortic diameter remains largely understudied.

METHODS

This was a cross sectional study of hypertensive Chinese adults from rural areas. The maximum infrarenal aortic diameter (maxIAD) from renal arteries to the iliac bifurcation was obtained by ultrasound. MaxIADs in different RHR groups were compared in males and females separately because of the significant differences between sexes. Multiple regression analysis was used to determinate the correlation between RHR and maxIAD. Further interactions between three factors (BMI, smoking, and anti-hypertensive regimens) and RHR for maxIAD were examined using subgroup analysis.

RESULTS

19,200 subjects were enrolled in the study, with an average age of 64.8±7.4 years and 61.6% females. Only 22 cases (0.11%) were detected with AAA, with males (n = 17) presenting a higher AAA incidence than females (n = 5). In subjects ≥65 years, there were 18 (0.19%) AAA, and 15 (83.3%) had a history of smoking. In the total subjects, the mean maxIAD ranged from 15.7±2.1 mm to 15.2±2.2 mm as RHR changed from the lowest quartile to the highest (≥84 bpm) in males, with a similar tendency observed in females. The correlation coefficient of RHR on maxIAD was -0.17 in males and -0.12 in females. Further subgroup analysis revealed that smoking exaggerated the correlation between RHR and maxIAD, but only in females.

CONCLUSIONS

A low AAA incidence was observed in this hypertensive Chinese population. There was a negative association between RHR and maxIAD, potentially exaggerated by smoking, especially in females.

A SNP in the 3'-UTR of HSF1 in dairy cattle affects binding of target bta-miR-484

The heat shock transcription factor 1 gene (HSF1) plays a key role in the heat stress response. We previously found a single nucleotide polymorphism (SNP) in the 3'-untranslated region (g.4693G>T) of HSF1 that was related to thermo tolerance in Chinese Holstein cattle through association analysis. However, it is not known whether other SNPs also affect thermo tolerance.In this study a novel SNP, g.1451G>T, was identified by DNA sequencing and genotyped using creating restriction site-polymerase chain reaction methodology. The g.1451G>T polymorphic site met Hardy-Weinberg equilibrium (P > 0.05). Association analysis demonstrated that this SNP had no effect on thermo tolerance traits in Holstein cattle. Findings of the study compared to the analysis of g.4693 G>T further indicated that g.4693 G>T may play an important role in thermo tolerance, although the mechanism is not clear. RNA hybrid and Targetscan prediction showed that the minimum free energy hybridization of bta-miR-484 with HSF1 3'-UTR was -31.9 kcal/mol and g.4693 G>T was in the seed sequence of bovine HSF1 that binds to bta-miR-484. Analysis by Luciferase assay indicated that HSF1 expression was directly targeted by bta-miR-484 in HEK 293T cells, and the Rluc/luc ratio of wildtype (GG) was lower than that of the mutant (TT) (P < 0.05). These results suggest that g.4693 G>T affects binding of HSF1 to bta-miR-484.

A single-nucleotide polymorphism of CCL21 rs951005 T>C is associated with susceptibility of polymyositis and such patients with interstitial lung disease in a Chinese Han population

OBJECTIVES

Our objective was to better understand the roles of single nucleotide polymorphisms (SNPs) in the CCL21, ERBB3, and TERT genes region in the development of idiopathic inflammatory myopathies (IIMs), we explored the associations between SNPs in the mentioned three genes and IIMs susceptibility in a Chinese Han population.

METHODS

Chinese polymyositis (PM) patients (n =291), dermatomyositis (DM) patients (n=526) and ethnically-matched healthy controls (n =968) were genotyped for the CCL21 region SNPs (rs951005 and rs2492358), ERBB3 (rs2292239 and rs11171739), and TERT (rs2853676 and rs10069690), by using the Sequenom MassArray system.

RESULTS

Our study indicated strong allele and genotype associations between rs951005 (OR: 1.65, 95%CI: 1.18-2.30, Pc=0.015; Pc=0.041, respectively) in CCL21 gene and PM patients. Additionally, rs951005 was associated with interstitial lung disease (ILD) in PM patients (Pc =0.01), and was associated with PM patients in additive model. However, the Chinese Han PM/DM patients and controls had statistically similar frequencies of alleles, genotypes and different genetic models (additive, dominant, and recessive) of ERBB3 and TERT polymorphisms.

CONCLUSIONS

This was the first study to demonstrate that the CCL21 gene SNP (rs951005) might confer genetic predisposition to PM patients or such patients with ILD in a Chinese Han population.

P1BS, a conserved motif involved in tolerance to phosphate starvation in soybean

Available phosphate (Pi) is a major limiting factor for plant growth, development, and productivity. Phosphate starvation response 1 (PHR1) is a binding dimer that binds to an imperfect palindromic sequence. PHR1-binding sequences (GnATATnC) exist in the promoter of Pi starvation-responsive structural genes, indicating an effect occurring downstream in the Pi starvation signaling pathway. These sequences are referred to as PHR1-binding site (P1BS) structures. In this study, the sequences of GmPHR1 and GmSPX1 from Glycine max (L.) Merr. soybean were determined and analyzed. We found that GmPHR1 is an MYB-related transcription factor. In addition, GmSPX1 contained a P1BS structure, which is an important cis-regulatory motif in the phosphate signaling pathway. We found that GmPHR1 can physically interact with GmSPX1 through the cis-element, which may be a major pathway for the GmPHR1-mediated Pi starvation stress response. Thus, the P1BS structure in the Pi starvation signaling pathway is an important cis-regulatory motif that improves the tolerance to low phosphorus conditions in soybean.

Control of the metal-insulator transition in VO₂ epitaxial film by modifying carrier density

External controlling the phase transition behavior of vanadium dioxide is important to realize its practical applications as energy-efficient electronic devices. Because of its relatively high phase transition temperature of 68 °C, the central challenge for VO2-based electronics, lies in finding an energy efficient way, to modulate the phase transition in a reversible and reproducible manner. In this work, we report an experimental realization of p-n heterojunctions by growing VO2 film on p-type GaN substrate. By adding the bias voltage on the p-n junction, the metal-insulator transition behavior of VO2 film can be changed continuously. It is demonstrated that the phase transition of VO2 film is closely associated with the carrier distribution within the space charge region, which can be directly controlled by the bias voltage. Our findings offer novel opportunities for modulating the phase transition of VO2 film in a reversible way as well as extending the concept of electric-field modulation on other phase transition materials.

Role of Nrf2 signal pathway in rats with deep hypothermia ischemia/reperfusion injury undergoing remote postconditioning

We investigated the protective effects of remote postconditioning (RPC) in the lungs of rats with deep hypothermia ischemia/reperfusion (I/R) injury and the role of nuclear factor E2-related factor 2 (Nrf2) signaling in this process. Forty-nine rats were randomly divided into a sham control group, deep hypothermia I/R group, RPC group, I/R+all-trans retinoic acid (ATRA) group, I/R+RPC+ATRA group, I/R+tert-butylhydroquinone (tBHQ) group, and I/R+RPC+tBHQ group. Real-time polymerase chain reaction and Western blot analysis were used to examine Nrf2 mRNA and protein expression, respectively. Compared with the sham control group, Nrf2 expression, malondialdehyde (MDA) content, and the wet/dry weight (W/D) ratio were significantly increased in the I/R group, while superoxide dismutase (SOD) activity was significantly decreased. Pulmonary Nrf2 expression and SOD activity was significantly increased, and MDA content and the W/D ratio were significantly decreased in the RPC group compared with the I/R group. Compared with the I/R group, MDA and W/D ratio significantly decreased and SOD activity remarkably increased in I/R+tBHQ group. After ATRA intervention in the I/R+ATRA group, MDA content and W/D ratio increased and SOD activity decreased compared to the I/R group. MDA content and W/D ratio in the RPC+tBHQ group significantly decreased and SOD activity increased compared with in the RPC group (P < 0.01). In the RPC+ATRA group, MDA content and W/D ratio decreased while SOD activity increased compared with the RPC group (P < 0.01). RPC alleviated deep hypothermia I/R injury; the Nrf2 signaling pathway may be involved in the protective effects induced by RPC.

Strain dynamics of ultrathin VO₂ film grown on TiO₂ (001) and the associated phase transition modulation

Tuning the metal insulator transition (MIT) behavior of VO2 film through the interfacial strain is effective for practical applications. However, the mechanism for strain-modulated MIT is still under debate. Here we directly record the strain dynamics of ultrathin VO2 film on TiO2 substrate and reveal the intrinsic modulation process by means of synchrotron radiation and first-principles calculations. It is observed that the MIT process of the obtained VO2 films can be modulated continuously via the interfacial strain. The relationship between the phase transition temperature and the strain evolution is established from the initial film growth. From the interfacial strain dynamics and theoretical calculations, we claim that the electronic orbital occupancy is strongly affected by the interfacial strain, which changes also the electron-electron correlation and controls the phase transition temperature. These findings open the possibility of an active tuning of phase transition for the thin VO2 film through the interfacial lattice engineering.

Common characteristics shared by different differential phase contrast imaging methods

There are many variations of differential phase contrast imaging methods. Although these imaging methods are different in configuration, they are alike in imaging by extracting differential phase information through the evaluation of the refraction angles. In this paper, we investigate common characteristics shared by various different differential phase contrast imaging methods.

A novel cytotoxic T lymphocyte epitope analogue with enhanced activity derived from cyclooxygenase-2

Cyclooxygenase-2 is a promising target for cancer immunotherapy. Here, we designed the analogues p321-9L and p321-1Y9L (YLIGETIKL) from cyclooxygenase-2-derived native peptide p321. Then, we tested the binding affinity and stability of the analogues and their ability to elicit specific immune response both in vitro (from PBMCs of HLA-A*02⁺ healthy donors) and in vivo (from HLA-A2.1/K(b) transgenic mice). Our results indicated that the activity of cytotoxic T lymphocytes induced by p321-9L and p321-1Y9L was more potent than that of p321. In conclusion, the epitope analogue, especially p321-1Y9L, may be a good candidate which could be used to the immunotherapy of patients with tumours expressing cyclooxygenase-2.

A new boronic acid-based fluorescent sensor for L-dihydroxyphenylalanine

Catecholamines, such as dopamine and L-dihydroxyphenylalanine (L-DOPA), are associated with different physiological functions and diseases. In our recent studies, a novel water-soluble boronic acid compound 3c was identified as a selective fluorescent sensor for L-DOPA. This compound not only has the ability to interact with dopamine and catechol, but also has no fluorescence intensity change for L-DOPA precursors in vivo, such as L-tyrosine.

Enhancement of bandgap emission of Pt-capped MgZnO films: important role of light extraction versus exciton-plasmon coupling

We present on a systematic study of the contribution of surface plasmon (SP) coupling and light extraction toward emission enhancement of Platinum (Pt) nano-patterns capped MgZnO films. Time resolved Photoluminescence (PL) results indicate that the Pt coating can greatly reduces the non-radiative recombination rate by passivation of surface states, making the decay slow down. Temperature dependence of the integrated photoluminescence intensity reveals that the Pt nano-patterns can offer a large amount of light transfer and scattering, which enormously increase the light extraction efficiency up to 3.8-fold. These results indicate that the increased light extraction efficiency caused by surface modification via Pt coating rather than SP coupling plays a dominant role in increasing bandgap emission of MgZnO film.

Potassium doping effect on the lattice softening and electronic structure of Ba(1-x)K(x)Fe(2)As(2) probed by X-ray absorption spectroscopy

Ba(1-x)K(x)Fe(2)As(2) superconducting samples (x = 0, 0.2, 0.4, 0.5) were synthesized by the solid-state reaction method. In this contribution the doping effect of potassium on the lattice dynamics in this newly discovered Ba(1-x)K(x)Fe(2)As(2) superconductor has been investigated by extended X-ray absorption fine-structure spectroscopy. The analysis shows that with potassium doping an increased disorder in the iron layers is mainly related to the softening of the Fe-Fe bond. Information about the electronic structure of these materials has also been obtained by looking at the X-ray absorption near-edge structure spectra that point out the presence of holes in the Fe-3d/As-4p hybridized orbital of the BaFe(2)As(2)-based system.

Comparison of dental education and professional development between mainland China and North America

Different educational and professional developments within the dental field create different sets of missions, norms, and practices regarding dental diseases and their appropriate treatment. This review has addressed differences in dental education and professional development between mainland China and North America. Many factors influence the choice of model and it is very difficult to predict which model will become predominant. However, there is growing sentiment that the independent faculty model in North America is logical and superior to the model, which 'integrates' dental and medical education in mainland China. Many North America dental schools place a high priority on preclinical and clinical training in the curriculum in order to expose students to patient oral health needs and systemic dental problems much earlier than in mainland China. North America dental schools promote and embrace students self-learning skills by the use of PBL, CRL, and TRAD education methodologies and new e-based technologies and approaches whereby students learn rather than are taught. In mainland China, the traditional lecture-based format is still employed in the majority of dental schools; however, strategies to enhance students self-learning skills is increasingly utilised in most well-known Chinese dental schools. The Chinese dental education model, which treats dentistry as a sub-specialty of medicine, has brought about fundamental differences, with the dentist functioning essentially as a stomatologist. For example, China has built up a large oral and maxillofacial surgery society, and craniofacial surgery is performed to a much broader extent by Chinese dentists than by most North American counterparts. In North America, dentists engage in full-time work, attend continuing training/education programmes, belong to an association, gain legal status, and construct a code of ethics emphasising the quality of care delivered to the public. Currently, continuing dental education in North America is available through a variety of venues involving licensing authorities, universities and private programmes. The concept of professional development in mainland China is relatively new and is still considered primarily in the context of promotion or achieving a higher professional title. Mandatory continuing dental professional education requirements do not guarantee the competence of members of the profession. Today, the Chinese government and society place increasing emphasis upon the accountability of self-regulating professions. Rather than attempting to summarise the current scope of dental education and professional development between mainland China and North America, this paper hopes to enhance mutual understanding, and promote greater academic exchanges in dental education.

Local structural disorder in REFeAsO oxypnictides by RE L(3) edge XANES

The REFeAsO (RE = La, Pr, Nd and Sm) system has been studied by RE L(3) x-ray absorption near edge structure (XANES) spectroscopy to explore the contribution of the REO spacers between the electronically active FeAs slabs in these materials. The XANES spectra have been simulated by full multiple scattering calculations to describe the different experimental features and their evolution with the RE size. The near edge feature just above the L(3) white line is found to be sensitive to the ordering/disordering of oxygen atoms in the REO layers. In addition, shape resonance peaks due to As and O scattering change systematically, indicating local structural changes in the FeAs slabs and the REO spacers due to RE size. The results suggest that interlayer coupling and oxygen order/disorder in the REO spacers may have an important role in the superconductivity and itinerant magnetism of the oxypnictides.

The mechanism of Al donor defects in (Zn, Co)O:Al: a view from resonant x-ray spectroscopies

We studied the effect of Al doping in Zn(0.94)Co(0.05)Al(0.01)O nano-powders from the electronic structure point of view by applying x-ray absorption spectroscopy and resonant inelastic x-ray scattering at the oxygen K- and Co L-edges. The intensity of the pre-edge structure of the O-K XAS spectra is enhanced following the introduction of the Al defect. Multiple scattering calculations demonstrate it can be accounted for by the gain of the hybridization strength between O 2p and Al 3p (and/or Co 3d) states. The consensus on the hybridization strength is reached by combining Co-L XAS and RIXS investigations and multiplet calculations. It reveals different spatial substitutions of Al doping can alter the number of shared oxygen atoms between the Co and Al tetrahedrons. These shared ligands are responsible for the Al 3p and Co 3d state hybridization strength as well as the ferromagnetism of the ground state. The magnetic difference is better understood to be governed by various shared oxygen atoms rather than the distance between the Al defect and Co impurities.

Nanocontact resistance and structural disorder induced resistivity variation in metallic metal-oxide nanowires

Several systems of metallic metal-oxide nanowires (NWs), including pure RuO2 and as-implanted and annealed Ru(0.98)Cu(0.02)O2 and Ru(0.93)Cu(0.07)O2 NWs, have been employed in two-probe electrical characterizations by using a transmission electron microscope-scanning tunneling microscope technique with a gold tip. Thermal, mechanical, and electron beam exposing treatments are consecutively applied to reduce the electrical contact resistance, generated from the interface between the NW and the gold tip, so as to evaluate the intrinsic NW resistance. It is found that the residual contact resistance cannot be entirely removed. For each system of metallic metal-oxide NWs, several tens of NWs are applied to electrical characterizations and the total resistances unveil a linear dependence on the ratio of the length to the area of the NWs. As a result, the average resistivity and the contact resistance of the metallic metal-oxide NWs could be evaluated at room temperatures. The average resistivities of pure RuO2 NWs agree well with the results obtained from standard two- and four-probe electrical-transport measurements. In addition, the as-implanted Cu-RuO2 NWs reveal disordered crystalline structures in high-resolution TEM images and give higher resistivities in comparison with that of pure RuO2 NWs. The residual contact resistances of all kinds of metallic metal-oxide NWs unveil, more surprisingly, an approximation value of several kilohms, even though the average resistivities of these NWs change by more than one order of magnitude. It is argued that the ductile gold tip makes one or more soft contacts on the stiff metal-oxide NWs with nanometer roughness and the nanocontacts on the NWs contribute to the electrical contact resistance.

First Report of Bacterial Head Rot of Broccoli Caused by Pseudomonas fluorescens in China

During warm and humid periods in the winters from 2005 to 2008, head rot symptoms on broccoli (cv. Sijilv) (Brassica oleracea L. var italica Planch) were observed in commercial fields in Ningbo, Zhejiang Province, China. In agreement with the report of Cui and Harling (1), water-soaked lesions developed on the buds and then progressed into a brown-black soft rot. Longitudinal sections of the symptomatic inflorescences showed brown discoloration and rotting of the internal tissues. Broccoli production is hampered by the disease, with disease incidence ranging from 65 to 81%. Bacteria were isolated by streaking on nutrient agar (3) and individual colonies formed after 2 to 3 days of incubation at 28°C. Fifteen of thirty isolates induced hypersensitive reactions (HR) on tobacco leaves (Nicotiana tabacum cv. Samsun) within 48 h. All the HR-positive strains were fluorescent on King's medium B and the colonies were smooth, convex, entire, and round. Classical bacteriological tests indicated that the fluorescent strains were gram negative, obligate aerobes, arginine dihydrolase positive, and oxidase positive. Also, the fluorescent strains were positive for the production of levan from sucrose. Five representative strains were further characterized by the Biolog Microbial Identification System, version 4.2 (Biolog Inc., Hayward, CA) and gas chromatography of fatty acid methyl esters (FAME) using the Microbial Identification System (MIDI Inc., Newark, DE) with the aerobic bacterial library (TSBA50). The five strains were identified as Pseudomonas fluorescens with Biolog and FAME similarity indexes of 0.61 to 0.68 and 0.52 to 0.58, respectively. The 16S rRNA gene sequence of broccoli strain PFB-01 (GenBank Accession No. GQ352649) was determined according to Li et al. (2). A subsequent GenBank search showed that this sequence had 98% nucleotide identity with the type strain of P. fluorescens (ATCC 17386^T, GenBank Accession No. AF094726). Koch's postulates were completed by the inoculation of broccoli heads (cv. Sijilv) with cell suspensions (10⁷ CFU/ml) of the above five strains by spraying on the surface of subcorymbs. Each treatment had five replicates. All strains induced head rot symptoms similar to those observed in natural infections. No symptoms were noted on the control plants inoculated with sterile water. Bacteria were successfully reisolated from symptomatic heads and confirmed by the cellular fatty acid composition. To our knowledge, this is the first report in China that P. fluorescens is the causal pathogen of bacterial head rot of broccoli. References: (1) X. Cui and R. Harling. Phytopathology 96:408, 2006. (2) B. Li et al. J. Phytopathol. 154:711, 2006. (3) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society. St. Paul, MN, 2001.

Correlation between local vibrations and metal mass in AlB2-type transition-metal diborides

Lattice vibrations have been investigated in TiB2, ZrB2 and HfB2 by temperature-dependent extended X-ray absorption fine structure (EXAFS) experiments. Data clearly show that the EXAFS oscillations are characterized by an anomalous behavior of the Debye-Waller factor of the transition-metal-boron pair, which is suggested to be associated with a superposition of an optical mode corresponding to phonon vibrations induced by the B sublattice and an acoustic mode corresponding to the transition-metal (TM) sublattice. Data can be interpreted as a decoupling of the metal and boron vibrations observed in these transition-metal diborides (TMB2), a mechanism that may be responsible for the significant reduction of the superconducting transition temperature observed in these systems with respect to the parent MgB2 compound. The vibrational behavior of TM-TM bonds has also been investigated to study the occurrence of anisotropy and anomalies in the lattice vibrational behavior of TM-TM bonds.

Dysprosium compounds studied by resonant inelastic X-ray scattering and high-resolution X-ray absorption near edge structure spectroscopy

A set of resonant inelastic X-ray scattering (RIXS) studies focusing on the 2p64f(n)-->2p54f(n)5d1(2p54f(n+1)5d0)-->2p63d94f(n)5d1(2p63d94f(n+1)5d0) channel of dysprosium in Dy metal, Dy2O3, DyNi3 and Dy25Fe18 compounds have been carried out. Data showed with high statistics and resolution, the different delocalization degree of the 5d band of dysprosium in these compounds, e.g., decreasing from Dy metal to DyNi3, Dy25Fe18 and to dysprosium oxide, in agreement with the high-resolution XANES (HRXANES) spectra. Band structure calculations performed on Dy metal and Dy2O3 confirm both RIXS and HRXANES results in the increasing delocalization of the dysprosium 5d band in Dy metal with respect to Dy2O3. The 5d orbital occupancies of DyNi3 and Dy25Fe18 alloys have been also studied by comparison of the HRXANES white line (WL) area with the behavior of the final states energy position in RIXS spectra and we show that DyNi3 has a higher 5d orbital occupancy than Dy25Fe18.

Lattice vibrational property in the transition-metal diboride ZrB2

Lattice vibrational property has been determined in ZrB(2) system using the temperature-dependent extended X-ray-absorption fine-structure (EXAFS) technique from room temperature to 28K. The smooth behavior of Debye-Waller factor curve with temperature is slightly abnormal for the first pair Zr-B. In order to reproduce this curve, an improved Einstein mode with two Einstein frequencies has been used. The quantitative analysis of temperature-dependent Debye-Waller factor of Zr-B pair shows one Einstein frequency is very high and the other is small. These frequencies correspond to the vibration of boron layer atoms and transition-metal layer atoms, respectively. Based on the Einstein mode with one frequency, the vibrational frequency for Zr-Zr pair has been also obtained. Zirconium diboride has two types of Zr-Zr interaction. One is in-plane and the other is out-of-plane along the high symmetry axis. Our analysis shows there is a little difference between in-plane Zr-Zr vibration and out-of-plane one. And the smaller Einstein vibrational frequency for the Zr-B shell is just between the two ones of the Zr-Zr shells. Our results show that the lattice vibrational behavior in ZrB(2) presents obvious particularity and anisotropy.

A new iterative algorithm to reconstruct the refractive index

The latest developments in x-ray imaging are associated with techniques based on the phase contrast. However, the image reconstruction procedures demand significant improvements of the traditional methods, and/or new algorithms have to be introduced to take advantage of the high contrast and sensitivity of the new experimental techniques. In this letter, an improved iterative reconstruction algorithm based on the maximum likelihood expectation maximization technique is presented and discussed in order to reconstruct the distribution of the refractive index from data collected by an analyzer-based imaging setup. The technique considered probes the partial derivative of the refractive index with respect to an axis lying in the meridional plane and perpendicular to the propagation direction. Computer simulations confirm the reliability of the proposed algorithm. In addition, the comparison between an analytical reconstruction algorithm and the iterative method has been also discussed together with the convergent characteristic of this latter algorithm. Finally, we will show how the proposed algorithm may be applied to reconstruct the distribution of the refractive index of an epoxy cylinder containing small air bubbles of about 300 micro of diameter.

Orbital susceptibilities of PbSe quantum dots

Different sizes of three-dimensional PbSe quantum dots have been synthesized for the study of orbital magnetic susceptibilities. Two types of orbital susceptibilities have been found, including the Curie susceptibility and finite-size corrections to the Landau susceptibility. The Curie term of a quantum dot manifests itself in the temperature dependence of magnetic susceptibility at low temperatures, while the field dependence of differential susceptibility at high temperatures shows finite-size corrections to the Landau susceptibility. Both of the two kinds of orbital susceptibility, estimated per quantum dot, show linear dependence on the size.

Structural Characterization of Nickel Oxide Nanowires by X-ray Absorption Near-Edge Structure Spectroscopy

Nickel oxide nanowires modified by poly(vinylpyrrolidone) (PVP) were synthesized via a simple chemical pattern. For the first time NiO nanowires with diameters ranging from 40 to 100 nm with the expected ratio (length vs diameter) ranging from 54 to 90 were grown using a simple solution-phase approach (mild method). These nickel nanowires exhibited unique photoluminescence features and displayed a significant UV luminescence. X-ray absorption near-edge spectroscopy has been used to characterize the local Ni environment and identify the electronic structure. Comparing experimental and theoretical spectra at the Ni and O K edges, we determine the lattice distortion via the analysis of the characteristic preedge features and the multiple-scattering structures detected in the X-ray absorption near-edge structure spectra. The correlation between experimental features and the disordered or distorted local structures is also discussed.

XANES quantitative structural determination of the sandwich bis(naphthalocyaninato) cerium complex

The molecular structure of the sandwich double-decker bis(naphthalocyaninato) cerium complex was determined for the first time in a quantitative way using a new method of analysis of the Ce L3-edge X-ray absorption near-edge structure (XANES) in the framework of the full multiple scattering theory. An average Ce-N bond length of 2.47 A was determined. In this complex structure the pyrrole rings play the key role in the determination of the XANES spectral features, and the differences in bond lengths between the Ce atom and the eight pyrrole N atoms are 0.14 A, addressing a significant distortion of these rings around cerium. These results may be used to study double-decker imidazole rings, present as the structure model in the photosynthesis center and in sandwich-structured lanthanide chlorophyll molecules.

Ischemic preconditioning: tolerance to hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion (I/R) injury still remains an unresolved problem in both liver resectional surgery and liver transplantation and may be responsible for liver failure, lung injury and death. The current review summarizes the findings reported to date on the effectiveness of ischemic preconditioning against liver and lung damage associated with hepatic I/R injury and the underlying protective mechanisms. The effect of ischemic preconditioning on the mechanisms potentially involved in hepatic I/R injury, including alterations in energy metabolism, neutrophil accumulation, microcirculatory disturbances, formation of proinflammatory mediators, such as endothelin and tumor necrosis factor-alpha, and reactive oxygen species generation have been evaluated. In this review, we address the role of preconditioning in the increased vulnerability of fatty livers to hepatic I/R injury. The effectiveness of ischemic preconditioning versus pharmacological strategies that could simulate the benefits of liver preconditioning has been also discussed.

Liver ischemic preconditioning: a new strategy for the prevention of ischemia-reperfusion injury

Ischemic preconditioning renders the liver more tolerant to ischemia-reperfusion injury in warm and cold ischemia-reperfusion models. In general, the application of a 5 to 10-minute period of ischemia followed by 10 minutes of reperfusion confers early effective protection to the liver. Mechanisms responsible for this endogenous protective effect include: (1) transient nitric oxide production during liver preconditioning; (2) diminution of toxic reactive species generated on reperfusion; (3) remote effect on extrahepatic organs such as lung, kidney, and pancreas; (4) preservation of energy metabolism during ischemia; and (5) involvement of nuclear transcription factor and others.

Saturable dose-response relationships for melphalan in melanoma treatment by isolated limb infusion in the nude rat

Nude rats bearing melanomas on their hindlimbs were treated by isolated limb infusion (ILI) with increasing doses (7.5-400 microg/ml) of melphalan. The response of tumours to treatment at the end of the observation period was graded, according to diameter, as complete response (CR), partial response (PR), no change (NC) or progressive disease (PD). No linear relationship between the dose of melphalan and the tumour response was observed. All doses above a threshold of 15 microg/ml achieved a PR or CR. The achievement of CR was not related to increased dose. Two major implications arise from this work. Firstly, the typically two- to three-fold increase in cytotoxic drug concentration given in high dose chemotherapy compared with standard drug concentration may not be sufficient to produce the expected increase in tumour response and possibly survival, and the controversial results of high dose chemotherapy in different studies may thus be explained. Secondly, since an increase in melphalan dose above a certain threshold does not greatly increase tumour response, the use of combination therapies would seem to be more likely to be effective than increased chemotherapeutic drug doses in achieving better tumour responses.

[The analgesic and antispasmodic effects of guang tong xiao aerosol of TCM]

OBJECTIVE

To observe the analgesic and antispasmodic effects of Guang Tong Xiao Aerosol (GTXA).

METHOD

Writhing test and tail-flick of physical stimulation were made to study the analgesic effect on mice and rats.

RESULT AND CONCLUSION

GTXA given by gastrogavage in dose of 18.75 g.kg-1 or 12.50 g.kg-1 could markedly raise the pain threshold after chemical stimulation in mice and physical stimulation in rats, and had antispasmodic effects.

Pharmacokinetics and pharmacodynamics of melphalan in isolated limb infusion for recurrent localized limb malignancy

Isolated limb infusion (ILI) is an attractive, less complex alternative to isolated limb perfusion (ILP). It has a lower morbidity in treating localized recurrences and in transit metastases of the limb for tumours such as melanoma, Merkel cell tumour and Kaposi's sarcoma, allowing administration of high concentrations of cytotoxic agent to the affected limb under hypoxic conditions. Melphalan is the preferred cytotoxic agent for the treatment of melanoma by ILP or ILI. We report pharmacokinetic data from 12 patients treated by ILI for tumours of the limb in Brisbane. The kinetics of drug distribution in the limb was calculated using a two-compartment vascular model, where both tissue and infusate act as well-stirred compartments. Analysis of melphalan concentrations in the perfusate during ILI showed good agreement between the values measured and the concentrations predicted by the model. Recirculation and wash-out flow rates, tissue concentrations and the permeability surface area product (PS) were calculated. Correlations between the PS value and the drug concentrations in the perfusate and tissue were supported by the results. These data contribute to a better understanding of the distribution of melphalan during ILI in the limb, and offer the opportunity to optimize the drug regimen for patients undergoing ILI.

Renewable amperometric immunosensor for Schistosoma japonium antibody assay

A renewable amperometric immunosensor has been proposed for the determination of Schistosoma japonium antibody (SjAb) in rabbit serum. A paraffin-graphite-Schistosoma japonium antigen (SjAg) biocomposite, which needs no additional curing, was directly used to construct the immunosensors. The analytical sample containing the desired SjAb was mixed with SjAb labeled with horseradish peroxidase (HRP) to form the incubation solution for the competitive binding assay. Amperometry was used to determine the amount of HRP fixed on the sensor surface, which was related to the content of desired SjAb. Assay conditions were optimized, including the selection of substrate, the loading of SjAg in the biocomposite, the amount of labeled SjAb in the incubation solution, the incubation time, and the temperature. Using o-aminophenol (o-AP) as a substrate, amperometric detection at -200 mV (vs SCE) resulted in a pseudolinear detection range of about 0.36 to 14 microg/mL, with a detection limit of 0.36 microg/mL. Rabbit serum samples with varying infection degrees were analyzed, and the results demonstrated that the concentration that is detectable in this system meets the demands of clinical analyses. A new surface on the immunosensor for use in another competitive assay can be obtained by removing the original one and polishing the surface.

Mutation analysis and the correlation between genotype and phenotype of Arg778Leu mutation in chinese patients with Wilson disease

BACKGROUND

The defective gene (ATP7B) that causes Wilson disease (WD) codes for a putative copper-transporting P-type adenosine triphosphatase. After cloning of ATP7B, the spectrum of mutations and their clinical consequences have been investigated in patients with WD in different ethnic populations. However, the spectrum of mutations and the correlation of genotype-phenotype in the Chinese population have not been extensively studied.

OBJECTIVE

To investigate the characterization of mutations of ATP7B and the correlation between genotype and phenotype in the Chinese population.

METHODS

We studied 60 unrelated healthy Chinese and 65 unrelated Chinese families, including 84 patients with WD and 126 parents. Genomic DNA was prepared from peripheral blood leukocytes using a salt-precipitation method. Polymerase chain reaction single-strand conformation polymorphism and subsequent direct sequencing were used to identify the mutations and polymorphisms of ATP7B. Statistical analysis was performed using t test or chi(2) test.

RESULTS

We identified 18 mutations (7 novel) and 11 polymorphisms (3 novel). The novel mutations are -36C-->T, Trp650ter, Gln914ter, 2810delT, Thr935Met, Arg1041Pro, and Glu1173Lys. The novel polymorphisms are 1168A-->G (Ile390Val), 2785A-->G (Ile929Val), and 3316G-->A (Val1106Ile). Two mutations, Arg778Leu and Thr935Met, are relatively frequent, representing 37.7% and 10.0% of patients, respectively. To our knowledge, we are the first to report the correlation between the genotype and phenotype of Arg778Leu. The result shows that Arg778Leu homozygotes are associated with the early onset of WD with hepatic presentation.

CONCLUSIONS

The Arg778Leu and Thr935Met mutations are hot spots in the Chinese population. The features of mutations of ATP7B differ between the Chinese and Western ethnic populations. The Arg778Leu mutation has severe effects on the function of ATP7B. These findings are valuable for developing a fast and effective method to diagnose the presence of the WD gene.

Febrile and acute hyperthermia enhance TNF-induced necrosis of murine L929 fibrosarcoma cells via caspase-regulated production of reactive oxygen intermediates

Previous studies have demonstrated the essential role of TNF-induced reactive oxygen intermediates (ROI) in the necrosis of L929 cells. We investigated the molecular basis for the interaction of hyperthermia and TNF in these cells. Hyperthermia, both febrile (40.0-40.5 degrees C) and acute (41.5-41.8 degrees C), strongly potentiated TNF killing, and sensistization was significantly quenched by the antioxidant, BHA. The broad-spectrum caspase inhibitor, Z-VAD, has been shown to markedly increase the TNF sensitivity of L929 cells at 37 degrees C; we observed that hyperthermia would also enhance the sensitivity of L929 cells to TNF + Z- VAD and that BHA could significantly quench the response, as well. The basis for hyperthermic potentiation was unlikely thermally-increased sensitivity to ROI, as treatment with hydrogen peroxide for 24 h killed L929 cells essentially equivalently, whether incubated continuously at 37 degrees C or at 40.0-40.5 degrees C, or for 2 h at 41.5-41.8 degrees C. However, febrile and acute hyperthermia markedly increased TNF-induced production of ROI, with or without Z-VAD. Hyperthermia dramatically accelerated the onset of this production, as well as the onset of necrotic death, as determined by oxidation of dihydro-rhodamine and propidium iodide staining, respectively, both of which were significantly quenchable with BHA. We conclude that hyperthermia potentiates TNF-mediated killing in this cell model primarily by increasing the afferent, and not the efferent, phase of TNF-induced necrosis.

NEXAFS multiple scattering calculations of KO2

Since many years the oxidation of alkali metals has being attracted much interest due to the catalytic properties of metal promoters and the simple electronic structure of alkali atoms. The alkali-oxides phase diagram indicates that the interaction of oxygen with alkali metals can lead to the formation of different atomic O2- ions and molecular O2(-) and O(2)2- ions. Potassium superoxide has been prepared in situ and high resolution O k-edge absorption NEXAFS spectra have been measured at the VUV beam-line at ELETTRA facility. The experimental data have been analyzed by multiple scattering approach deriving many geometrical and electronic details. In particular, we have found that the growth material structure is of the KO2 type with an O-O distance of about 1.35A and that the transition involving single pi molecular empty state of the superoxide O2(-) anion has a fine structure. Multiple Scattering self consistent calculation indicates that the bond between oxygen anion and K atom is totally ionic and that the fine structure is essentially due to solid state effects.

[Contents of ten trace elements in Epimedium acuminatum Franch. and its different processed products]

OBJECTIVE

Determine and compare the contents of ten trace elements in crude E. acuminatum and its three different processed products.

METHOD

Using flame atomic absorption spectrometry.

RESULT

The ten trace elements were found in both the crude drug and its three processed products, and in terms of contents some of the trace elements in all the three processed products are higher than those in the crude drug.

CONCLUSION

According to the trace element contents, the three processed products of E. acuminatum have their own advantages. It is thus suggested that thoroughgoing clinical and experimental researches be performed anew for the long-shelved processing methods.

Antibacterial activity of a chitooligosaccharide mixture prepared by cellulase digestion of shrimp chitosan and its application to milk preservation

The antibacterial activity of a chitooligosaccharide mixture prepared by digestion of shrimp chitosan with cellulase at 50 degrees C for 14 h was evaluated. Sugars with 1 to 8 degrees of polymer (DP) were found in this chitooligosaccharide mixture, and the weight percentage of sugars with DP > or = 6 was 44.3%. Minimal lethal concentrations of this mixture against Aeromonas hydrophila, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, Shigella dysenteriae, Staphylococcus aureus, Vibrio cholerae, and Vibrio parahaemolyticus in nutrient broth were 5 to 29 ppm, which were much lower than those of the chitosan reactant (50 to 1,000 ppm). The antibacterial activity of this mixture in the sterilized milk against E. coli O157, L. monocytogenes, Salmonella Typhimurium, and S. aureus was much stronger at 4 degrees C than at 37 degrees C. When raw milk was supplemented with either 0.24% or 0.48% (wt/vol) of this oligosaccharide mixture and stored at 4 degrees C for 12 days, its mesophilic and psychrotrophic counts were reduced by at least 3 log cycles, and there was very little change in pH. In addition, this mixture retarded the growth of Salmonella species and caused quicker reduction of Staphylococcus species in raw milk. Accordingly, the shelf life of raw milk at 4 degrees C was extended by at least 4 days.

[Contents of general flavonoides in Epimedium acuminatum Franch. and its differently-processed products]

OBJECTIVE

Determining and comparing the contents of general flavonoides in four kinds of differently-processed products of Epimedium acuminatum.

METHOD

Determining the contents by ultraviolet spectrophotometry.

RESULT

The contents were found in the following seguence: unprocessed product, clearly-fried product, alcohol-broiled product, salt-broiled product, sheep-fat-broiled product. The average recovery rate was 96.01%, with a 0.74% RSD(n = 5).

CONCLUSION

Heating causes the contents of general flavonoides in the processed products to decrease. These processed products are still often used in clinical treatment, for the reason that the adjuvant features certain coordinating and promoting functions. The study is to be pursued further.

[Techniques in experimental surgery-general anesthesia of the goat]

To find an appropriate anesthesia for the goat in experimental surgery.METHODS:15 goats were operated on with intravenous anestheia using ketamine hydrochloride-gamma-OH-pentobarbital as anesthetic agents.They were grouped according to the weight.The physiologic index,drug dosage,operating time and awaking time were compared.RESULTS:There's no significant difference among the groups(P>0.05). All goats were anesthesised well,with advantage of long operating time(2.5-3.5h)and short awaking time(2-10min).CONCLUSION:The method reduces the drug dosage of intravenous anesthesia using pentobarbital as an anestheic,with minimal respiratory and cirulatory depression.gamma-OH can prolong the duration of general anesthesia and reduce ketamine's maintenance dosage.Endotracheal intubation rssured safety of operation.The method is simple,safe with satisfactory anesthetic effects.

Can tissue drug concentrations be monitored by microdialysis during or after isolated limb perfusion for melanoma treatment?

Isolated limb perfusion (ILP) with melphalan is used to treat recurrent melanoma. This study aimed to develop a microdialysis technique for melphalan tissue concentration measurement during ILP. The effects of melphalan concentration (50-600 microg/ml), microdIalysis flow rate (0.55-17.5 microl/min), probe length (5-50 mm) and temperature (25-41.5 degrees C) on in vitro recovery were studied. In addition, in vivo recovery was measured in rat hindlimbs perfused with melphalan using 50 mm microdialysis probes implanted subcutaneously and into muscle. Both dialysate and tissue sample melphalan concentrations were determined by high performance liquid chromatography. The in vitro recovery of melphalan was not affected by melphalan concentration or temperature, but increased with probe length and decreased with flow rate. The melphalan concentrations in subcutaneous and muscle dialysates were not significantly different. A linear relationship was found between tissue dialysate concentrations and actual tissue concentrations of melphalan (r2 = 0.97). Microdialysis is a potential method for tissue drug monitoring which may assist in the efficacious use of cytotoxics in human ILP.

[Simulation of gas chromatographic peak motion process]

Solute motion process under different temperature, pressure and/or flow program conditions is simulated with the aid of numerical calculation of the differential equation. It is demonstrated that there exist some differences between the normalized average linear velocity and the normalized local linear velocity. As time develops, they intercept, and may not reach the column end at the same time, thus may result in errors in retention time simulation. In constant pressure process, where the compressibility factor (j) does not change, simulation results in a model index of 1, and no model difference can be found when the integrate equation is used. In pressure varying process, where j changes by time, simulation results in an model index which deviates to 1, and positive (for a j decrease process) or negative (for a j increase process) error can be found when the integrate equation is used. The numerical solution of the differential equation is singular under given programs, which corresponds to a specific space line in z, t, u coordinates.

Relative dispersion of intravascular transit times during isolated human limb perfusions for recurrent melanoma

AIMS

We have characterized the relative dispersion of vascular and extravascular markers in the limbs of three patients undergoing isolated limb perfusions with the cytotoxic melphalan for recurrent malignant melanoma both before and after melphalan dosing.

METHODS

A bolus of injectate containing [51Cr] labelled red blood cells, [14C]-sucrose and [3H]-water was injected into an iliac or femoral artery and outflow samples collected at 1 s intervals by a fraction collector. The radioactivity due to each isotype was analysed by either gamma [51Cr] or beta [14C and 3H] counting. The moments of the outflow fraction-time profiles were estimated by a nonparametric (numerical integration) method and a parametric model (sum of two inverse Gaussian functions).

RESULTS

The availability, mean transit time and normalised variance (CV2) obtained for labelled red blood cells, sucrose and water were similar before and after melphalan dosing and with the two methods of calculation but varied between the patients.

CONCLUSIONS

The vascular space is not well-stirred but characterized by a CV2 similar that reported previously for in situ rat hind limb and rat liver perfusions. A flow-limited blood-tissue exchange was observed for the permeating indicators. Administration of melphalan did not influence the distribution characteristics of the indicators.

Tissue and perfusate pharmacokinetics of melphalan in isolated perfused rat hindlimb

Melphalan is commonly used as a cytotoxic agent in isolated limb perfusion for locally recurrent malignant melanoma. The time course of melphalan concentrations in perfusate and tissues during a 60-min melphalan perfusion and 30-min drug-free washout in the single-pass perfused rat hindlimb was examined using a physiologically based pharmacokinetic model. The rat hindlimbs were perfused with Krebs-Heinseleit buffer containing 4.7% bovine serum albumin (BSA) or 2.8% dextran 40 at a constant rate of 3.8 ml/min. The concentration of melphalan in perfusate and tissues was determined by high-performance liquid chromatography. The tissue concentrations of melphalan were significantly higher with the perfusate containing dextran than BSA during the 60-min perfusion. During the washout period, the melphalan concentration in the perfusates decreased rapidly in first few minutes, followed by a slower monoexponential decline. The estimated half life (t1/2) for melphalan removal from skin and fat was 59 +/- 2 min for both BSA and dextran perfusates. However, the estimated t1/2 for melphalan removal from muscle was 79 and 96 min for BSA and dextran washout perfusates, respectively. The predicted concentration-time profiles obtained for melphalan with BSA and dextran perfusates appear to correspond closely to the observed data. This study showed that the uptake of melphalan into perfused tissues is impaired by the use of perfusates in which melphalan is highly bound. Melphalan washout from muscle, but not skin and fat, was facilitated by the use of perfusates in which melphalan is highly protein bound.

[Effect of yishen xiezhou recipe on mesangium cell of chronic renal failure rats]

OBJECTIVE

To observe the effect of Yishen Xiezhuo Recipe (YSXZR) on glomerular mesangium cell (MSC) proliferation.

METHODS

YSXZR was given to healthy and experimental CRF rats by gastrogavage, and the effect of their serum on MSC proliferation was observed.

RESULTS

The serum could obviously inhibit the MSC proliferation. Compared with control rats to which physiological saline was given, the difference was significant (P < 0.01).

CONCLUSION

YSXZR could postpone CRF progress.

Resolution and response-time dependence of ferroelectric liquid-crystal optically addressed spatial light modulators on grating profiles

We introduce a model to analyze the time response of an optically addressed spatial light modulator (OASLM) when a two-dimensional image is written on it. Comparison with experimental results is performed by use of gratings as input images. For a given spatial frequency, we show that the response time of the device depends on the grating profile. The effect of the time-constant mechanism is demonstrated theoretically and experimentally for a sinusoidal-wave and a square-wave intensity profile. An alternative explanation for the resolution limitation of the OASLM that is related to the time-constant mechanism and a new method for measuring the resolution of the device are proposed.

Melphalan dosing regimens for management of recurrent melanoma by isolated limb perfusion: application of a physiological pharmacokinetic model based on melphalan distribution in the isolated perfused rat hindlimb

The optimal dosing schedule for melphalan therapy of recurrent malignant melanoma in isolated limb perfusions has been examined using a physiological pharmacokinetic model with data from isolated rat hindlimb perfusions (IRHP). The study included a comparison of melphalan distribution in IRHP under hyperthermia and normothermia conditions. Rat hindlimbs were perfused with Krebs-Hen-seleit buffer containing 4.7% bovine serum albumin at 37 or 41.5 degrees C at a flow rate of 4 ml/min. Concentrations of melphalan in perfusate and tissues were determined by high performance liquid chromatography with fluorescence detection. The concentration of melphalan in perfusate and tissues was linearly related to the input concentration. The rate and amount of melphalan uptake into the different tissues was higher at 41.5 degrees C than at 37 degrees C. A physiological pharmacokinetic model was validated from the tissue and perfusate time course of melphalan after melphalan perfusion. Application of the model involved the amount of melphalan exposure in the muscle, skin and fat in a recirculation system was related to the method of melphalan administration: single bolus > divided bolus > infusion. The peak concentration of melphalan in the perfusate was also related to the method of administration in the same order. Infusing the total dose of melphalan over 20 min during a 60 min perfusion optimized the exposure of tissues to melphalan whilst minimizing the peak perfusate concentration of melphalan. It is suggested that this method of melphalan administration may be preferable to other methods in terms of optimizing the efficacy of melphalan whilst minimizing the limb toxicity associated with its use in isolated limb perfusion.

Altered vascular norepinephrine responses in portal hypertensive intestine: role of PKA and guanylate cyclase

The purpose of the present study was to determine whether selective blockade of adenosine 3',5'-cyclic monophosphate (cAMP)- or guanosine 3',5'-cyclic monophosphate (cGMP)-mediated events modulated norepinephrine responses in intestinal microvessels of normal and portal hypertensive rats. Vascular norepinephrine responses were evaluated before and after inhibition of cAMP-dependent protein kinase [protein kinase A(PKA)] with Rp-adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS) or guanylate cyclase with LY-83583. Male Sprague-Dawley rats were divided into two groups: those with portal hypertension by portal vein stenosis and normal controls. The small intestine was prepared for microcirculatory studies. Arteriolar diameter and erythrocyte velocity were monitored, and microvascular flow was calculated from velocity and diameter data. The preparation was challenged with incremental concentrations of norepinephrine before and after addition of Rp-cAMPS (50 microM) or LY-83583 (30 microM). Arteriolar diameter and blood flow were significantly elevated in portal hypertensive rats; norepinephrine responses were significantly depressed. LY-83583 did not alter arteriolar diameter, blood flow, or norepinephrine responsiveness in normal or portal hypertensive rats. Rp-cAMPS did not affect arteriolar diameter, blood flow, or norepinephrine responsiveness in normal rats. However, in portal hypertensive rats, Rp-cAMPS reduced blood flow by approximately 20% (P < 0.05) and completely restored vascular norepinephrine responses to normal. The results indicate that cAMP- but not cGMP-dependent events are primarily responsible for the loss of microvascular norepinephrine responsiveness in portal hypertensive intestine.