Iterative approach to Maxwell equations for dielectric media of spatially varying refractive index

We propose an iterative method to solve the Maxwell equations for a one-dimensional model system with spatially varying permittivity. We construct solutions that are iterative in the scattering order, equivalent to the number of scattering events along the forward and backward directions. A numerical implementation of this approach is also presented.

Postglacial recolonization and cpDNA variation of silver birch, Betula pendula

Chloroplast PCR-RFLP markers were used to reconstruct the history of the silver birch, Betula pendula Roth, in Europe since the last glacial maximum (LGM). In birch, fossil pollen maps do not reveal a clear chronological sequence of postglacial spread. If anything, the pollen record suggests that most of Europe was recolonized by birches as early as 10000 bp, probably from populations that remained close to the ice sheets during the LGM. The geographical distribution of haplotypes supports a scenario of early colonization. Two of the 13 haplotypes that were observed are common, representing 35% and 49% of the total sample, respectively. Although one of the common haplotypes is predominant in the NW and the other in the SE, both are present throughout most of the investigated geographical area. Rare haplotypes are geographically restricted. The distribution of the haplotypes reveals five genetic boundaries between groups of haplotypes and allows us to infer patterns of postglacial recolonization. Europe was re-occupied by two main waves of recolonization: one eastern and one western, with origins at intermediate latitudes. Populations in the Iberian Peninsula and in Italy did not take part in the postglacial recolonization of Europe.

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

OBJECTIVE

To characterize the carotenoid content of selected components of the Mediterranean diet commonly eaten by Greek migrants to Melbourne, a population group maintaining a traditional dietary regimen, and who exhibit relatively high circulating carotenoid concentrations and low cardiovascular disease mortality. DESIGN AND SPECIMENS: Opportunistic sampling of wild (sow thistle, amaranth, purslane and dandelion, collected from roadsides and home gardens) and commercially available (chicory, endive) green leafy vegetables and figs in season. Foods were selected on the basis that they are commonly eaten by Greek migrants but not by Anglo-Celtic persons, and had not previously been well-characterized with respect to their carotenoid contents. Extra virgin, cold-pressed olive oil and 'extra light' olive oil were obtained from commercial sources. Specimens were extracted with tetrahydrofuran (or chloroform:methanol for olive oil) and carotenoid contents were quantified using HPLC with UV detection. Two to six specimens of greens and figs were analysed. Dietary intake was assessed by food frequency questionnaire.

RESULTS

Wild green vegetables contained high concentrations of lutein (sow thistle>amaranth>purslane>dandelion) and beta-carotene (sow thistle>amaranth>purslane=dandelion). Sow thistle and amaranth contained lutein (15 and 13 mg/100 g, respectively) and beta-carotene (3.3 and 4.0 mg/100 g, respectively) at concentrations greater than that seen in the commercially available species of chicory and endive. Figs contained all major carotenoids appearing in plasma, albeit at low concentrations. Extra virgin cold-pressed olive oil contained substantial quantities of lutein and beta-carotene, but the more-refined 'extra light' olive oil did not.

CONCLUSIONS

These components of the traditional Mediterranean diet contribute to the higher circulating concentrations of carotenoids in Greek migrants compared to Anglo-Celtic Australians.

SPONSORSHIP

This study largely funded by the National Health and Medical Research Council of Australia (grant no. 974098). Extra virgin olive oil donated by Picuba Foods, Marrickville, NSW, Australia.

Comparison of the Maxwell and Boltzmann theory for multilayered dielectric random media

Based on the transfer matrix theory for electromagnetic fields, we develop a corresponding theory for intensity transport in a one-dimensional random medium. We show the conditions for which the Maxwell equations, the intensity transport theory, and the Boltzmann equation can lead to similar predictions. We generalize the transfer matrix theory to study intensity modulated waves and compare its predictions with those obtained from the Maxwell and Boltzmann equations.

Photon-density waves in macroscopic and microscopic plane-parallel scattering samples

We investigate the validity of the Boltzmann equation to predict the reflection and transmission coefficients for an intensity modulated laser beam passing through a microscopic medium consisting of discrete scatterers. For a one-dimensional model system we demonstrate that the Boltzmann equation works remarkably well for small modulation frequencies, even to describe a medium comprised of only 10 scatterers. Discrepancies can be found only if the modulation wavelength of the laser intensity is commensurate with the spacing between the scatterers and if the medium is sufficiently ordered.

POR C of Arabidopsis thaliana: a third light- and NADPH-dependent protochlorophyllide oxidoreductase that is differentially regulated by light

During the sequencing of the genome of Arabidopsis thaliana a gene has been identified that encodes a novel NADPH-protochlorophyllide oxidoreductase (POR)-like protein (accession number AC 002560). This protein has been named POR C. We have expressed the POR C protein in Escherichia coli and have determined its in vitro activity. POR C shows the characteristics of a light-dependent and NADPH-requiring POR similar to POR A and POR B. The expression of the POR C gene differs markedly from that of the POR A and POR B genes. In contrast to the POR A and POR B mRNAs, the POR C mRNA has been shown previously to accumulate only after the beginning of illumination. In light-adapted mature plants only POR B and POR C mRNAs were detectable. The amounts of both mRNAs show pronounced diurnal rhythmic fluctuations. While the oscillations of POR B mRNA are under the control of the circadian clock, those of POR C mRNA are not. Another difference between POR B and POR C was found in seedlings that were grown under continuous white light. The concentration of POR C mRNA rapidly declined and soon dropped beyond the limit of detection, after these seedlings were transferred to the dark. On the other hand. POR B mRNA was unaffected by this light/dark shift. When seedlings were exposed to different light intensities, the amounts of POR B mRNA remained the same, while POR A and POR C mRNAs were modulated in an inverse way by these light intensity changes. POR A mRNA was still detectable in seedlings grown under low light intensities but disappeared at higher light intensities, while the mRNA concentration of POR C rose with increasing light intensities. These different responses to light suggest that the functions of the three PORs of Arabidopsis are not completely redundant, but may allow the plant to adapt its needs for chlorophyll biosynthesis more selectively by using preferentially one of the three enzymes under a given light regime.

SNAP-29: a general SNARE protein that inhibits SNARE disassembly and is implicated in synaptic transmission

Using the yeast two-hybrid system with syntaxin-1A as bait, we isolated soluble NSF attachment protein (SNAP)-29 from a human brain cDNA library. Synaptosomal fractionation and immunocytochemical staining of hippocampal neurons in culture showed that SNAP-29 is present at synapses and is predominantly associated with synaptic vesicles. The interaction of SNAP-29 with syntaxin-1 was further confirmed with immunoprecipitation analysis. Binding competition studies with SNAP-29 demonstrated that it could compete with alpha-SNAP for binding to synaptic SNAP receptors (SNAREs) and consequently inhibit disassembly of the SNARE complex. Introduction of SNAP-29 into presynaptic superior cervical ganglion neurons in culture significantly inhibited synaptic transmission in an activity-dependent manner. Although SNAP-29 has been suggested to be a general SNARE component in membrane trafficking, our findings suggest that it may function as a regulator of SNARE complex disassembly and modulate the process of postfusion recycling of the SNARE components.

Effect of precursor protein phosphorylation on import into isolated chloroplasts from Chlamydomonas

In higher plants, chloroplast-destined precursor proteins are thought to be phosphorylated. Mediated by a specific 14-3-3 protein, these phosphorylated proteins bind to the chloroplast surface and are subsequently imported into the chloroplast. We demonstrate that also in the green alga Chlamydomonas reinhardtii the precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase becomes phosphorylated by a plant protein kinase and that the phosphorylation site is located in the transit peptide. The phosphorylation status of the precursor protein regulates its import into chloroplasts especially at an early step during this process. The possible physiological function is discussed.

[Progress in researches on the molecular genetics of facioscapulohumeral muscular dystrophy]

Facioscapulohumeral muscular dystrophy(FSHD) is an autosomal dominant neuromuscular disorder characterized by progressive weakness of the facial, shoulder and upper arm muscles. The major gene involved has been mapped to chromosome 4q35. There is the evidence for genetic heterogeneity. The FSHD- associated DNA rearrangements are due to deletions of integral copies of the 3.3 kb tandem repeated unit from the subtelomeric region on chromosome 4q35. A valuable molecular diagnostic test for FSHD has been created with the use of p13E-11 probe to detect the EcoR I/Bln I double digestion fragment which is usually smaller in FSHD patient than in normal indivdual. Since the FSHD gene has not been identified yet, the exact molecular pathogenesis of FSHD remains unclear. The hypothesis of position effect variegation has been postulated as the underlying genetic mechanism of FSHD. FRG1 (FSHD region gene 1) from human chromosome 4q35 is identified as a candidate gene for FSHD. A significant correlation between the size of rearrangements associated with FSHD and the clinical phenotype has been found. The various rearrangement fragment size may explain the wide range of clinical severity in FSHD.

Improvements in circulating cholesterol, antioxidants, and homocysteine after dietary intervention in an Australian Aboriginal community

BACKGROUND

Poor nutrition contributes to high rates of coronary heart disease among Australian Aboriginal populations. Since late 1993, the Aboriginal community described here has operated a healthy lifestyle program aimed at reducing the risk of chronic disease.

OBJECTIVE

We evaluated the effectiveness of a community-directed intervention program to reduce coronary heart disease risk through dietary modification.

DESIGN

Intervention processes included store management policy changes, health promotion activities, and nutrition education aimed at high-risk individuals. Dietary advice was focused on decreasing saturated fat and sugar intake and increasing fruit and vegetable intake. Evaluation of the program included conducting sequential, cross-sectional risk factor surveys at 2-y intervals; measuring fasting cholesterol, lipid-soluble antioxidants, and homocysteine concentrations; and assessing smoking status. Nutrient intakes were estimated from analysis of food turnover in the single community store.

RESULTS

There was a significant reduction in the prevalence of hypercholesterolemia (age-adjusted prevalences were 31%, 21%, and 15% at baseline, 2 y, and 4 y, respectively; P < 0.001). There were significant increases in plasma concentrations of alpha-tocopherol, lutein and zeaxanthin, cryptoxanthin, and beta-carotene across the population. Retinol and lycopene concentrations did not change significantly. Mean plasma homocysteine concentrations decreased by 3 micromol/L. There was no significant change in smoking prevalence between the 2 follow-up surveys. There was an increase in the density of fresh fruit and vegetables and carotenoids in the food supply at the community store.

CONCLUSION

This community-directed dietary intervention program reduced the prevalence of coronary heart disease risk factors related to diet.

Comparison of simultaneous distillation extraction and solid-phase microextraction for the determination of volatile flavor components

Traditional simultaneous distillation extraction (SDE) and solid-phase microextraction (SPME) techniques were compared for their effectiveness in the extraction of volatile flavor compounds from various mustard paste samples. Each method was used to evaluate the responses of some analytes from real samples and calibration standards in order to provide sensitivity comparisons between the two techniques. Experimental results showed traditional SDE lacked the sensitivity needed to evaluate certain flavor volatiles, such as 1,2-propanediol. Dramatic improvements in the extraction ability of the SPME fibers over the traditional SDE method were noted. Different SPME fibers were investigated to determine the selectivity of the various fibers to the different flavor compounds present in the mustard paste samples. Parameters that might affect the SPME, such as the duration of absorption and desorption, temperature of extraction, and the polarity and structure of the fiber were investigated. Of the various fibers investigated, the PDMS-DVB fiber proved to be the most desirable for these analytes.

Hepatitis B virus nucleic acids circulating in the blood: distinct patterns in HBs carriers with hepatocellular carcinoma

Circulating nucleic acids in serum and plasma are common in a variety of disease conditions. Here, we focus (i) on our approach for the detection of various hepatitis B virus (HBV)-related nucleic acids in liver tissue and in serum, (ii) on the progression of the chronic HBV infection, (iii) on the relation of HBV-specific nucleic acids circulating in the blood of patients with hepatocellular carcinoma, and in general (iv) on the diagnostic potential of circulating HBV nucleic acids.

A study on the detection of weak photoacoustic signals by stochastic resonance

On the basis of stochastic resonance (SR) theory a study of the detection of photoacoustic (PA) signals without a lock-in amplifier is presented. The applicability of the SR method is investigated both with simulated signals calculated by use of a Gaussian model and with experimental PA signals. Signal-to-noise ratio (SNR) is improved substantially by adjusting the properties of a non-linear system to realize SR. By use of this method the lock-in amplifier can be removed from a PA spectrometer.

Expression, deletion [was deleton] and mutation of p16 gene in human gastric cancer

AIM

To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis, depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma.

METHODS

The expression of p16 protein was examined by streptavidin-peroxidase conjugated method (S-P);the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma.

RESULTS

Expression of p16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P < 0.05). The positive rate of p16 protein expression in mucoid carcinoma 10.00% (1/10) was significantly lower than that in poorly differentiated carcinoma 51.22% (21/41), undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/16) (P < 0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P < 0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas.

CONCLUSIONS

The expression loss of p16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.

Circulating hepatitis B virus nucleic acids in chronic infection : representation of differently polyadenylated viral transcripts during progression to nonreplicative stages

PURPOSE

Beside the established maturation of hepatitis B virus (HBV) transcripts at a polyadenylation signal downstream of the HBV x protein open reading frame, maturation at an internal polyadenylation signal has been observed in the chronically infected liver. In the present study, it was the aim to identify the respective circulating full-length and truncated transcripts in plasma/serum of carriers.

EXPERIMENTAL DESIGN

Nucleic acids extracted from sera were analyzed using established PCR and reverse transcription-PCR procedures targeted to HBV x protein gene regions. Amplification products were cloned and sequenced.

RESULTS

Base substitution patterns were determined, which indicated infection stages advanced to different degrees regardless of the transcript type analyzed. HBV full-length RNA (fRNA) showed a high correlation with hepatitis B e antigen and viral DNA, indicative for a replicative infection. In contrast, truncated RNA (trRNA) appeared to be independent of hepatitis B e antigen and showed only a weak association with circulating viral DNA. No correlation was observed between the levels of trRNA and the apparent liver damage as reflected by alanine transaminase levels. An age-dependent representation of fRNA and trRNA was observed: fRNA decreased progressively to low levels, whereas trRNA remained at comparably high values. trRNA and RNA not polyadenylated at either of the two polyadenylation signals were detected even in the absence of any other conventional HBV seromarker, including viral DNA. This was shown for patients with cryptogenic cirrhosis and hepatitis C virus carriers.

CONCLUSIONS

The identification of HBV RNA in human serum has a diagnostic potential for apparent and for inapparent infection stages.

Erythrocyte membrane protein abnormalities in beta-thalassemia of the Li nationality in Hainan

OBJECTIVE

To determine the composition of abnormal red cell membrane skeleton.

METHODS

By sodium dodecyl sulphate polyacrylamide gel electrophoresis of ghostcorpuscles, we quantified the amount of protein by densitometric evaluation.

RESULTS

The results showed that in beta-thalassemia, the amount of spectrin, 4.5 protein and globin significantly increased compared with the controls (26.05 +/- 1.46, 21.69 +/- 1.86; 22.87 +/- 5.61, 12.99 +/- 2.33; 15.23 +/- 3.31 and 4.97 +/- 2.73, respectively, P < 0.05).

CONCLUSION

These data suggest that the erythrocyte membrane protein composition matched with globin in patients with beta-thalassemia of the racial Li minority are different from the normal control. These factors increase rigidity but decrease deformability of the beta-thalassemic red cell membrane, which may lead to hemolytic anemia.

Cholangiocarcinoma with a background of hepatitis B virus-associated cirrhosis

Recently, hepatitis virus-associated chronic hepatitis or cirrhosis has been suggested to be involved in the pathogenesis of cholangiocarcinoma (CC). A 52-year-old man was diagnosed as CC with a background of hepatitis B virus (HBV)-dependent cirrhosis. A minute hepatic tumor was found during the follow-up, and was diagnosed as CC on percutaneous biopsy. The patient died of hepatic failure and an autopsy revealed the tumor to be a well to moderately differentiated adenocarcinoma. An immunohistological analysis of HBV X gene-encoded protein (HBX) was neither detected in the cancerous nor in the noncancerous tissue. No oncogenic role of the virus was verified in this case.

[Simultaneous determination of tryptophan, tyrosine and phenylalanine in injection by derivative fluorescent PLS method]

A new first-derivative fluorescent method by partial least squares (PLS) for the simultaneous determination of tryptophan, tyrosine and Phenylalanine was developed. The determination was carried out in KH2PO4-K2HPO4 buffer solution (pH = 7.4) and at the EX (excite) wavelength of 216.6 nm. The method has been applied to the determination of tryptophan, tyrosine and phenylalanine in compound amino acid injection, and the relative errors are within +/- 7.2%.

Varying competence for protein import into chloroplasts during the cell cycle in Chlamydomonas

By studying the import of radioactively labelled small subunit of ribulose-1,5-bisphosphate carboxylase (pSS) into chloroplasts of the green alga C. reinhardtii cw-15 protein delivery to chloroplasts was found to vary during the cell cycle. Chloroplasts were isolated from highly synchronous cultures at different time points during the cell cycle. When pSS was imported into 'young' chloroplasts isolated early in the light period about three times less pSS was processed to small subunit SS than in 'mature' chloroplasts from the middle of the light period. In 'young' chloroplasts also, less pSS was bound to the envelope surface. During the second half of the light period the import competence of isolated chloroplasts decreased again when based on chlorophyll content or cell volume, but did not change significantly when related to chloroplast number. Measurements of pSS binding to the surface of chloroplasts of different age indicated that the adaptation of protein import competence during the cell cycle is due to a variation of the number of binding sites per chloroplast surface area, rather than to modulation of the binding constant.

Rapid method for the isolation of full length adenoviral genomes by bacterial intermolecular homologous recombination

Recombinant adenoviruses are used widely in gene therapy research. Much work has been carried out to remove specific components of the wild type adenovirus (e.g. E1 gene) in order to make them safer for human use. In addition to such efforts, it is vitally important to ensure that the production of recombinant adenoviruses meet safety guidelines not only with regard to the absence of replication competent adenoviruses but for other variant species that may be present in a viral preparation. In this report, a time and cost efficient method is described for the isolation of full length adenovirus genomes without resorting to plaque purification. The procedure uses a bacterial homologous recombination system and results in the conversion of the double-stranded linear adenovirus genome into a circularized plasmid form that can be easily analyzed by restriction digestion, PCR, DNA sequencing or used in transient transfection studies. Also, the adenovirus plasmids that are generated may also be rescued back into virus form if needed. The entire procedure takes 4 days or less instead of weeks that plaque purification or dilution cloning requires. Furthermore, the method does not require the use of tissue culture materials or facilities. More importantly, this procedure allows for a more extensive and thorough examination of any viral preparation, since it allows for the detection of variants incapable of propagation without the assistance of co-infecting intact adenoviral genomes. Under standard conditions of plaque purification, these variant genomes are not detected. It is predicted that far more variant genomes will be observed using this rapid method than would otherwise be detected by standard plaque purification methods.

[Study on intramolecular energy transfer and relaxation processes of rare earth complexes by photoacoustic and fluorescence spectroscopy]

The excitation-relaxation processes of the solid Tb(III) complexes (Tb(AA)3.2H2O, Tb(AA)3 bpy and Tb(AA)3 phen) have been studied by photoacoustic spectroscopy (PAS) with the conjunction of fluorescence spectroscopy. The relaxation processes are studied from two aspects: nonradiative process and radiative process. The photoacoustic amplitude spectra and luminescence spectra of the complexes have been measured. Combined with the luminescence spectra, the PA amplitude spectra reflect the variation of the luminescence efficiency. According to the variation of the luminescence efficiency, the intramolecular energy transfer and relaxation processes of the complexes were studied. The suitability of the energy gap between the lowest triplet level of ligand and resonance energy level of rare earth ion is critical for efficient energy transfer.

Relativistic electron spin motion in cycloatoms

We present computer movies of the classical and quantum mechanical time evolution for an atom in a strong static magnetic field and a laser field. The resonantly induced relativistic motion of the atomic electron leads to a ring-like spatial probability density called a cycloatom. We further demonstrate that spin-orbit coupling for a fast moving electron in a cycloatom becomes significant, modifying the time-dependence of the spin even if initially aligned parallel to the static magnetic field direction. We also present several movies on time-evolution of the spin-distribution as a function of the position for a relativistic quantum state. The nature of such a space resolved spin measurement is analyzed.

[Study on neodymium complexes by broad wavelength range photoacoustic spectroscopy]

Neodymium complexes were studied by photoacoustic(PA) spectroscopy from UV-Vis to mid-IR. According to the PA spectra, low excited energy levels, relaxation processes and fluorescence properties were discussed. Then the influence of interaction between Nd(III) and ligands in solid complexes was investigated on the basis of band shifts and intensity change.

Numerical solution of the time-dependent Maxwell's equations for random dielectric media

We discuss how a spectral-domain method in combination with a split-operator technique can be used to calculate exact solutions of the time-dependent Maxwell's equations. We apply this technique to study the tunneling signal of an evanescent wave occurring due to frustrated total internal reflection and the propagation of a light pulse through an inhomogeneous medium consisting of multiple random scatterers.