Quantum interference and ballistic transmission in nanotube electron waveguides

The electron transport properties of well-contacted individual single-walled carbon nanotubes are investigated in the ballistic regime. Phase coherent transport and electron interference manifest as conductance fluctuations as a function of Fermi energy. Resonance with standing waves in finite-length tubes and localized states due to imperfections are observed for various Fermi energies. Two units of quantum conductance 2G(0) = 4e(2)/h are measured for the first time, corresponding to the maximum conductance limit for ballistic transport in two channels of a nanotube.

[Study on the elimination of bacterial endotoxins by ultrafiltration device]

An external-pressed polysulfone hollow fiber UF membrane, was made by phase inversion method. The cutoff molecular weight was 6000. The water permeation rate of this membrane module (psi 90 x 500 mm) is more than 150 L/hr.atm. The operating results show that the elimination of bacterial endotoxins by this membrane has reached the national standard in pharmacopoeia, and this technology is worthy to be extended over to medical industry. In addition, the essence of pyreotogen, the quantification units and measure methods for pyreotogen, and the operating conditions of UF device in the process of eliminating pyreotogen are introduced. Some critical points in operation was discussed.

[Study on the immunologic function of lymphocyte in cord blood]

OBJECTIVE

To explore immunologic function of T lymphocytes in human cord blood (HUCB) and provide theoretical basis for clinical application of HUCB.

METHODS

Immunophenotype and co-stimulated molecules were detected by flow-cytometry using a panel of double labelled McAb, intracellular cytokines (interferon-gamma, interleukin-4) secreted by T lymphocytes by micro-culture of whole blood, and CD25 expression of T lymphocyte by PHA stimulation. T lymphocytes from adult peripheral blood (PB) were used as control.

RESULTS

There are a higher CD4+/CD8+ ratio of T subset and a lower percentage of CD8+ lymphocytes in HUCB than that in adult PB (P < 0.01), and more than 90% of HUCB T-cells co-expressed CD45RA naive antigen which was significant higher than the percentage in adult PB (P < 0.01). The percentages of IFN-gamma and IL-4-producing CD4+ and CD8+ T cells from HUCB were lower than that of the control group. T cells in HUCB were able to be activated by PHA, but the phases of activation differed from adult PB T cells.

CONCLUSIONS

It suggested that the low ability to secret cytokines and high percentage of naive T cells might be responsible for the decreased incidence of acute and chronic GVHD and provided possible explanation for the clinical result in HUCB transplantation. T cells in HUCB is a potential resource of adoptive immunotherapy.

[Detection of telomerase activity in laryngeal carcinoma and the association between telomerase activity and lymphatic metastasis]

OBJECTIVE

To investigate the telomerase activity in human laryngeal squamous cell carcinomas (LSCC) and the association between telomerase activity and lymphatic metastasis.

METHOD

Telomerase activity was determined in 47 specimens of LSCC and 10 specimens of laryngeal inflammatory polyps using PCR-ELISA.

RESULT

Telomerase activity was detected in 39 of 47 (83%) LSCC, but was not detected in all 10 laryngeal inflammatory polyps. There were significant differences between them (P < 0.01). Telomerase activation in LSCC with positive cervical lymph node involvement appeared to be higher (13 out of 13 cases, 100%) than in LSCC with negative cervical lymph node involvement (26 out of 34, 76.47%), (P < 0.05).

CONCLUSION

Telomerase is activated frequently in LSCC and may become a biomarker of LSCC. The detection of telomerase activity in LSCC may have some value for predicting metastasis potential and prognosis and can guide the clinical practices applying selective neck dissection.

[Changes in respiratory and circulatory function during sequential invasive-noninvasive mechanical ventilation]

OBJECTIVE

To investigate the change of respiratory and circulatory function in COPD during sequential invasive-noninvasive mechanical ventilation.

METHODS

12 COPD patients with type II respiratory failure were ventilated via endotracheal intubation. When pulmonary infection was under control (the appearance of "PIC Window"), all patients were extubated and received mask ventilation. The parameters of hemodynamics oxygenation and esophageal pressure were measured during endotracheal ventilation and mask ventilation (3 hrs after extubation).

RESULTS

The change of respiratory and circulatory parameters were not significantly different between invasive mechanical ventilation and noninvasive mechanical ventilation (P > 0.05).

CONCLUSION

The respiratory and circulatory function of COPD patients remained stable during sequential invasive-noninvasive mechanical ventilation.

[Stress response of Nilaparvata lugens at high temperature and activities of its protective enzyme systems]

The nymphae and different wing-form adults of Brown Planthopper (BPH) were treated intermittently at 34 degrees C, 36 degrees C and 38 degrees C. During the process of heat shock treatment, the variation of the activities of the endogenous enzymes of protective system and the content of lipid peroxides (LPO) in BPH were researched. The results showed that the effect of heat shock treatments on CAT activity in 4th instar of nymphae was higher than that in 3rd and 5th instar. The CAT activity in BPH adults increased with the day-age, and 36 degrees C was the suitable temperature at which H2O2 was scavenged by CAT. The GSH-px activity was higher in old than that in young nymphae, and the ability of GSH-px to scavenge H2O2 was higher in old adults than in those adults emerged early. The activity of SOD had a positive correlation with the treated temperatures, and decreased with the increase of nymphae instar and the day-age of adults after emergence at the same temperature. The activities of CAT, GSH-px, and SOD in macropterous adults were higher than those in brachypterous adults. There were no significant difference for the activities of CAT, GSH-px and SOD between female and male adults (alpha > 0.05). The content of LPO in BPH increased with the rise of treated temperature, and also increased with the increase of instars in nymphae and day-age after emergence in adults at the same temperature. The LPO content was higher in brachypterous than in macropterous adults.

[Validation and comparison of ISO standard method for the examination of fluoride in drinking water]

The validation of ISO standard method for the examination of fluoride in drinking water was introduced. The test for compensating interference, standard curves, accuracy, precision and the minimum detection limit etc were included. The comparison between ISO method and others was made. The results indicated that the ISO method was better in anti-interference, wider linear range and higher precision. The points designed were reasonable. The method is superior to other methods in the same kind, and it should be adopted and extended.

[Predictive value of combined application of umbilical artery color Doppler velocimetry, nonstress testing and ultrasonography in monitoring umbilical cord entanglement]

OBJECTIVE

To explore the predictive value of combined application of umbilical artery color Doppler flow monitoring (CDFI), nonstress testing (NST) and ultrasonography in monitoring umbilical cord entanglement.

METHODS

1 860 cases of pregnant women between gestational ages of 37 approximately 42 weeks were studied 1 approximately 2 weeks before delivery by CDFI, nonstress testing (NST) and ultrasonography to monitor umbilical cord entanglement.

RESULTS

The prevalence rate of umbilical cord entanglement was 23.23% (432/1 860). Positive predictive value and negative predictive value were 95.4 % (412/432) and 98.6% (1 408/1 428) respectively. The rate of accuracy was 97.8% (1 820/1 860). The rate of fetal distress among the fetuses with umbilical cord round the body or four limbs was 85.29% (23/34) and the incidence of cesarean section in this group was 88.28% (30/34). The rate of fetal distress among the fetuses with umbilical cord round the neck was 13.06% (52/398) and the incidence of cesarean section in this group was 44.94% (178/398). The rates of fetal distress and cesarean section were significantly higher in the group with umbilical cord around the body or four limbs than in the group with umbilical cord around the neck (chi(2) = 107.27 and 23.76 respectively, P < 0.001). The systolic/diastolic (S/D) ratio was basically in normal ranges in the group with the umbilical cord round the neck. In cardiotopography (CTG), umbilical cord entanglement mainly showed variable deceleration (VD), early deceleration (ED), nonreaction on NST, and late deceleration (LD) on oxytocin challenge test (OCT). Prolonged fetal heart rate deceleration (PD) could be seen in the group with umbilical cord around the body or four limbs.

CONCLUSION

The combined application of umbilical artery color Doppler velocimetry, nonstress testing and ultrasonography have an important auxiliary value in monitoring umbilical cord entanglement. It remarkably increases the positive predictive rate as a valuable reference for the choice of delivery form.

Expression profiling using microarrays fabricated by an ink-jet oligonucleotide synthesizer

We describe a flexible system for gene expression profiling using arrays of tens of thousands of oligonucleotides synthesized in situ by an ink-jet printing method employing standard phosphoramidite chemistry. We have characterized the dependence of hybridization specificity and sensitivity on parameters including oligonucleotide length, hybridization stringency, sequence identity, sample abundance, and sample preparation method. We find that 60-mer oligonucleotides reliably detect transcript ratios at one copy per cell in complex biological samples, and that ink-jet arrays are compatible with several different sample amplification and labeling techniques. Furthermore, results using only a single carefully selected oligonucleotide per gene correlate closely with those obtained using complementary DNA (cDNA) arrays. Most of the genes for which measurements differ are members of gene families that can only be distinguished by oligonucleotides. Because different oligonucleotide sequences can be specified for each array, we anticipate that ink-jet oligonucleotide array technology will be useful in a wide variety of DNA microarray applications.

Longitudinal changes in pulmonary function and respiratory symptoms in cotton textile workers. A 15-yr follow-up study

To evaluate the chronic effects of exposure to cotton dust, a 15-yr follow-up study in cotton textile workers was performed in Shanghai, China from 1981 to 1996. Testing occurred four times during the 15-yr period. The achieved follow-up rates were 76-88% of the original 447 cotton textile workers, and 70-85% of the original 472 silk textile workers (as a control group). Identical questionnaires, equipment, and methods were used throughout the study. The prevalence of byssinosis increased over time in cotton workers, with 15.3% at the last survey versus 7.6% at the baseline, whereas no byssinosis was found in silk workers. More workers in the cotton group consistently reported symptoms than in the silk group, although symptom reporting varied considerably from survey to survey. Cotton workers had small, but significantly greater, adjusted annual declines in FEV(1) and FVC than did the silk workers. Years worked in cotton mills, high level of exposure to endotoxin, and across-shift drops in FEV(1) were found to be significant determinants for longitudinal change in FEV(1), after controlling for appropriate confounders. Furthermore, there were statistically significant associations between excessive loss of FEV(1) and byssinosis, chest tightness at work, and chronic bronchitis in cotton workers. Workers who consistently (three or four of the surveys) reported byssinosis or chest tightness at work had a significantly greater 15-yr loss of FEV(1). We conclude that long-term exposure to cotton dust is associated with chronic or permanent obstructive impairments. Consistent reporting of respiratory symptoms, including byssinosis and chest tightness at work, is of value to predict the magnitude and severity of chronic impairments in textile workers.

Experimental annotation of the human genome using microarray technology

The most important product of the sequencing of a genome is a complete, accurate catalogue of genes and their products, primarily messenger RNA transcripts and their cognate proteins. Such a catalogue cannot be constructed by computational annotation alone; it requires experimental validation on a genome scale. Using 'exon' and 'tiling' arrays fabricated by ink-jet oligonucleotide synthesis, we devised an experimental approach to validate and refine computational gene predictions and define full-length transcripts on the basis of co-regulated expression of their exons. These methods can provide more accurate gene numbers and allow the detection of mRNA splice variants and identification of the tissue- and disease-specific conditions under which genes are expressed. We apply our technique to chromosome 22q under 69 experimental condition pairs, and to the entire human genome under two experimental conditions. We discuss implications for more comprehensive, consistent and reliable genome annotation, more efficient, full-length complementary DNA cloning strategies and application to complex diseases.

Yersinia enterocolitica O9 as a possible barrier against Y. pestis in natural plague foci in Ningxia, China

A survey of Yersinia spp, as related to plague control, was made in Haiyuan of Ganning loess plateau plague focus, Yanchi of Inner Mongolia plateau plague focus, and Yinchuan city, as a control area, in Ningxia, China. In Haiyuan, where the main plague reservoir was Mongolian ground squirrel (Citellus alaschanicus) living in the prairie, Y. enterocolitica O9 was frequently isolated from pigs, dogs, rodents living in and around houses, but only rarely from hare and Mongolian ground squirrel. In Yanchi, where the main plague reservoir was Mongolian gerbil (Meriones unguiculatus) living in the prairie and Y. pestis, which was isolated from rodents up to 1991, Y. enterocolitica O9 was sometimes isolated from pigs and rodents. In all areas, some strains of Y. enterocolitica O3 and Y. pseudotuberculosis serotypes 3 and 4b were also isolated from pigs, dogs, and from rodents. We propose that an epidemiological link exists between the prevalence of Y. pestis and Y. enterocolitica O9 in domestic and rodents living in these areas in China. The residential area in Haiyuan may be protected against Y. pestis by the domestic animals and rodents which acquired cross-protection against Y. pestis by infection with Y. enterocolitica O9, but this is not the case in the Yanchi district.

Modulated chemical doping of individual carbon nanotubes

Modulation doping of a semiconducting single-walled carbon nanotube along its length leads to an intramolecular wire electronic device. The nanotube is doped n-type for half of its length and p-type for the other half. Electrostatic gating can tune the system into p-n junctions, causing it to exhibit rectifying characteristics or negative differential conductance. The system can also be tuned into n-type, exhibiting single-electron charging and negative differential conductance at low temperatures. The low-temperature behavior is manifested by a quantum dot formed by chemical inhomogeneity along the tube.

The zinc finger protein schnurri acts as a Smad partner in mediating the transcriptional response to decapentaplegic

In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specification during embryogenesis and in imaginal disc development. Dpp signaling culminates in the phosphorylation and nuclear translocation of Mothers against dpp (Mad), a receptor-specific Smad that can bind DNA and regulate the transcription of Dpp-responsive genes. Genetic analysis has implicated Schnurri (Shn), a zinc finger protein that shares homology with mammalian transcription factors, in the Dpp signal transduction pathway. However, a direct role for Shn in regulating the transcriptional response to Dpp has not been demonstrated. In this study we show that Shn acts as a DNA-binding Mad cofactor in the nuclear response to Dpp. Shn can bind DNA in a sequence-specific manner and recognizes sites within a well-characterized Dpp-responsive promoter element, the B enhancer of the Ultrabithorax (Ubx) gene. The Shn-binding sites are relevant for in vivo expression, since mutations in these sites affect the ability of the enhancer to respond to Dpp. Furthermore we find that Shn and Mad can interact directly through discrete domains. To examine the relative contribution of the two proteins in the regulation of endogenous Dpp target genes we developed a cell culture assay and show that Shn and Mad act synergistically to induce transcription. Our results suggest that cooperative interactions between these two transcription factors could play an important role in the regulation of Dpp target genes. This is the first evidence that Dpp/BMP signaling in flies requires the direct interaction of Mad with a partner transcription factor.

[The effect of HCPT combined with radiation on cell proliferation of human lung adenocarcinoma cell line (D₆) in vitro]

BACKGROUND

To study the adjuvant effects of HCPT and radiation on cell proliferation of human lung adenocarcinoma cell line (D₆) in vitro.

METHODS

Suppression rate of cell growth,apoptosis and cell cycle of human pulmonary adenocarcinoma cell line were detected by MTT assay,DNA agrose electrophoresis and flow-cytometry respectively.

RESULTS

The suppression effects of HCPT on cell proliferation were dose and time dependent.The cells were significantly blocked at S stage by HCPT.Apoptosis peak appeared at 24 and 48 hours after treatment with high concentration (50μg/ml) and low concentration of HCPT (1μg/ml) respectively.DNA "Ladder" started to appear at 48 hours by radiation alone,but DNA "Ladder" and apoptosis peak both appeared at 24-72 hours and 0-72 hours after treatment with HCPT alone and HCPT combined with radiation respectively.

CONCLUSIONS

HCPT combined with radiation may show the synergistic killing effect on human lung adenocarcinoma cell line (D₆) in vitro.

[The meridian flowing and ancient Chinese philosophy]

The theories of Yin - Yang and Five - Evolutive phase were extensively applied after pre - Qin and both Han dynasties. In the Song - Ming dynasties, the background of New Confucianism, the achievements of art of Yi(Changes) advocated by the "School of Configuration - Arithmatic" were applied, in which the method of "Adopting of Jia" was almost entirely derived from the above school, mixing the theories of heavenly stems - earthly branches, Five - evolutive phases and Yin - Yang as a whole. An ancient system of Chronological treatment was thus established creatively by integrating clinical experience together. The system is a tight system of grafting medicine and philosophy formed on the basis of successfully utilizing the philosophical framework, thinking proposed by ancient physicians with keen observation and deep ponderation. The system is, by then, an advanced one, which is also an inevitable one.

[Detection of soluble endothelial protein C receptor (sEPCR) in patients with CHD, DM and SLE]

OBJECTIVE

To evaluate the clinical significance of plasma soluble endothelial protein C receptor (sEPCR) level in patients with coronary heart disease (CHD), diabetes mellitus (DM) and systemic lupus erythematosus (SLE).

METHODS

ELISA of antibody-sandwiched principle was used to detect sEPCR in 34 patients with CHD, 42 with DM-II, 63 with SLE and 20 normal controls (NC).

RESULTS

The plasma level of sEPCR in patients with DM was higher than that in NC group (P < 0.05). The sEPCR level in SLE patients with thrombosis and non-thrombosis are higher than that in NC group (P < 0.005 and P < 0.001, respectively). There is no significant difference between the two groups of SLE (P > 0.05), and between the CHD and NC groups.

CONCLUSION

sEPCR level increased in DM and SLE, it seems related to the process of inflammatory reaction and damage of endothelial cell.

Functional discovery via a compendium of expression profiles

Ascertaining the impact of uncharacterized perturbations on the cell is a fundamental problem in biology. Here, we describe how a single assay can be used to monitor hundreds of different cellular functions simultaneously. We constructed a reference database or "compendium" of expression profiles corresponding to 300 diverse mutations and chemical treatments in S. cerevisiae, and we show that the cellular pathways affected can be determined by pattern matching, even among very subtle profiles. The utility of this approach is validated by examining profiles caused by deletions of uncharacterized genes: we identify and experimentally confirm that eight uncharacterized open reading frames encode proteins required for sterol metabolism, cell wall function, mitochondrial respiration, or protein synthesis. We also show that the compendium can be used to characterize pharmacological perturbations by identifying a novel target of the commonly used drug dyclonine.

Prevalence of Alzheimer's disease and other dementing disorders in an urban community of Beijing, China

A door-to-door two-phase study was used to investigate the prevalence of senile dementia in an urban community of Beijing. In the study population, 5,003 individuals aged 60 years and older (>/=65 years, n = 3,728) were screened at home with the Chinese version of the MMSE. Persons who screened positive for dementia, using different cutoff scores based on degree of literacy, were further evaluated using the criteria of DSM-III-R and ICD-10. Among subjects who screened positive in phase I, 134 were diagnosed as having dementia in phase II. The prevalence ratios of dementia were 2.68% in the population aged 60 years and older, and 3.49% in the population aged 65 years and older. The prevalence rates among those aged 65 years and older were 1.85% for Alzheimer's disease, 1.37% for vascular dementia and 0.27% for other dementia (including mixed dementia). The prevalence of all dementia and AD increased steeply with advancing age and was consistently higher in women, but it was not obviously higher for VaD in women. Alzheimer's disease was the commonest type of dementia. Our prevalence figures for dementia and AD are similar to those previously reported for China.

Widespread aneuploidy revealed by DNA microarray expression profiling

Expression profiling using DNA microarrays holds great promise for a variety of research applications, including the systematic characterization of genes discovered by sequencing projects. To demonstrate the general usefulness of this approach, we recently obtained expression profiles for nearly 300 Saccharomyces cerevisiae deletion mutants. Approximately 8% of the mutants profiled exhibited chromosome-wide expression biases, leading to spurious correlations among profiles. Competitive hybridization of genomic DNA from the mutant strains and their isogenic parental wild-type strains showed they were aneuploid for whole chromosomes or chromosomal segments. Expression profile data published by several other laboratories also suggest the use of aneuploid strains. In five separate cases, the extra chromosome harboured a close homologue of the deleted gene; in two cases, a clear growth advantage for cells acquiring the extra chromosome was demonstrated. Our results have implications for interpreting whole-genome expression data, particularly from cells known to suffer genomic instability, such as malignant or immortalized cells.

Intrinsic electrical properties of individual single-walled carbon nanotubes with small band gaps

Individual single-walled carbon nanotubes (SWNT) exhibiting small band gaps on the order of 10 meV are observed for the first time in electron transport measurements. Transport through the valence or conduction band of a small-gap semiconducting SWNT (SGS-SWNT) can be tuned by a nearby gate voltage. Intrinsic electrical properties of the Ohmically contacted SGS-SWNT are elucidated. An SGS-SWNT exhibits metal- or semiconductorlike characteristics depending on the Fermi level position in the band structure.

Controllable reversibility of an sp(2) to sp(3) transition of a single wall nanotube under the manipulation of an AFM tip: A nanoscale electromechanical switch?

A simulation of the deflection of a single wall nanotube under the manipulation of an atomic force microscope tip revealed the key feature characterizing the deformation at relatively small bending angles to be a reversible transition from sp(2) to sp(3) bonding configurations in the bending region, leading to a 2 orders of magnitude reduction in conductance consistent with our most recent experimental observation. A local analysis elucidating the underlying physics of the findings is also discussed.

Probing the roles of the only universally conserved leucine residue (Leu122) in the oligomerization and chaperone-like activity of Mycobacterium tuberculosis small heat shock protein Hsp16.3

To understand the role of the only universally conserved hydrophobic residue among all the members of the sHsp family, this extremely well conserved Leu122 residue in Hsp16.3 was replaced by valine, alanine, asparigine, or aspartate residues. Only very small amounts of the L122D and L122N mutant Hsp16.3 proteins were expressed in the transformed E. coli; however, both the L122V and L122A were readily expressed. The L122V and L122A mutant proteins had similar oligomeric structures to the wild-type protein at room temperature. Examination of the L122A mutant protein by native pore gradient PAGE and CD spectroscopy, however, revealed a smaller oligomeric size and different secondary structure at 37 degrees C. Both L122V and L122A mutant proteins exhibited significantly lowered chaperone activities. Observations reported here suggest a very important role of this only universally conserved Leu residue in both the formation of specific oligomeric structures and the molecular chaperone activities of Hsp16.3.