[Antigen presenting role of dendritic cell proliferated from peripheral blood monocytes in patients with chronic hepatitis B]

OBJECTIVE

To study the presenting effect of dendritic cell (DC) proliferated from peripheral blood monocytes in patients with chronic hepatitis B on HBsAg.

METHODS

DC proliferated from patient's peripheral blood monocytes by adding GM-CSF and IL-4 were incubated with HBsAg for 1.5h at different concentrations, then mixed with autologous T cell and cocultured in 96-well flat-bottomed microtiter plates for 5 d at 37 degrees C and 5% CO(2). (3)H-TdR was added 13h before the culture completion, and finally the cells were gathered and the cpm was tested.

RESULTS

The proliferation of T cell by DC treated by HBsAg is significantly higher than untreated.

CONCLUSION

DC cultured from peripheral blood monocytes in patients with chronic hepatitis B plays a role in presenting HBsAg.

Adenosquamous lung carcinoma: clinical characteristics, surgical treament and prognosis

OBJECTIVE

The effectiveness of surgical resection of adenosquamous carcinoma of the lung remains poorly defined because of the histology's relatively low frequency, the failure in most published series to separate adenosquamous carcinoma from the other variants of non-small cell lung carcinoma. To define the effectiveness of treatment of adenosquamous carcinoma, we have retrospectively reviewed our hospital experience over a 12-year period.

METHODS

Retrospectively reviewed 22 cases of adenosquamous carcinoma who were surgically treated, except one patient, in the PUMCH from Jan. 1985 to Aug. 1997. This series constitutes the 1.9% of a total of 1 245 patients with all types of surgical treatment for the primary lung cancer during the same time.

RESULTS

The adenosquanous carcinoma was mostly presented in the old patients with a mean age of 60 years and mostly located in the peripheral of lung (n = 20). The overall 5-year survival was 23%. Those with stage I tumors survival was only 18% (n = 13), stage II 5%. The survival in stage III tumos was not longer than 25 months and in stage IV survival was not longer than 12 months.

CONCLUSION

Our results suggest that adenosquamous carcinoma of lung was a virulent tumor, which exhibited highly aggressive biological behavior with early lymph nodes metastasis (46%) and its prognosis was worse than that of both squamous cell carcinoma and adenocarcinoma.

[Effect of elevated CO2 concentration on photosynthesis and antioxidative enzyme activities of wheat plant grown under drought condition]

The photosynthesis and antioxidative enzyme activities of wheat plants grown in two open-top chambers with CO2 concentrations of 350 mumol.mol-1 and 700 mumol.mol-1 were examined under drought stress. The result showed that elevated CO2 concentration obviously enhanced the photosynthesis, stomatal resistance and water use efficiency, but decreased the transpiration of wheat. Doubled CO2 concentration significantly increased the activities of CAT, POD and SOD, which enhanced the abilities of antioxidative defence and drought tolerance.

Fas ligand expression and apoptosis in primary rat hepatocytes induced by lipopolysaccharide

OBJECTIVE

To study hepatocyte apoptosis induced by lipopolysaccharide (LPS) directly and indirectly, and to elucidate the mechanisms of liver damage in endotoxemia.

METHODS

Rat hepatocytes were isolated using collagenase perfusion, and cultured in RPMI 1640 medium. After 24h or 48 h of LPS treatment at various concentrations (1, 5, 10 mug/ml), membrane-bound Fas ligand (mFasL) expression in hepatocytes was determined by immunocytochemistry, and apoptosis was detected by TUNEL. In another set of experiments it was examined whether LPS-treated hepatocytes and its supernatants can stimulate apoptosis in LPS-untreated hepatocytes.

RESULTS

LPS markedly stimulated mFasL expression and apoptosis in hepatocytes in a dose and time (24-48 h) dependent manner. In the co-culture system LPS-treated hepatocytes significantly induced LPS-untreated hepatocyte apoptosis. In contrast, there was no apoptotic cells observed in the supernatant stimulation system.

CONCLUSION

LPS not only directly causes hepatocyte apoptosis, but also indirectly induces apoptosis of LPS-untreated hepatocytes by way of stimulating mFasL expression in hepatocytes.

[Response of wheat seedlings with different drought resistance to water deficiency and NaCl stresses]

The growth, photosynthesis, transpiration and antioxidative defence system of the seedlings of drought-tolerant wheat strain 8139 and drought-sensitive strain Ganmai No. 8 at 20% PEG 6000 and 1.2% NaCl stresses were compared. The results showed that strain 8139 had a strong drought resistance, but a weak salt resistance. The root growth of both wheat strains was inhibited significantly under salt stress, but stimulated slightly under drought stress. The net photosynthetic rate and water use efficiency of strain 8139 were significantly different from those of Ganmai No. 8 at every stage under both drought and salt stresses, and its transpiration rate was significantly different from that of Ganmai No. 8 only at 7th and 14th day after being stressed. The MDA content in strain 8139 after being stressed for 7 days was much lower than that in Ganmai No. 8 under drought stress, but there was no significant difference between the two strains under NaCl stress. Correspondingly, there was no significant difference in the fructan content and SOD and APX activities between strain 8139 and Ganmai No. 8, but a significant difference in GSH content was found under salt stress. Under drought stress, the contents of fructan and GSH and the activities of SOD and APX in strain 8139 were much higher than those in Ganmai No. 8 at different stage, and strain 8139 exhibited a strong antioxidative defence ability.

Construction of the recombinant retrovirus vector of HBV-S gene and it's expression in eukaryotic cells

OBJECTIVE

To investigate the effectiveness of recombinant retrovirus vector in gene therapy.

METHODS

The retroviral vector PLXSN-S was constructed and transferred into PA317 by means of electroporation, then HepG(2), P815, and EL4 cells were infected with the pseudovirus produced from PA317, which highly expressed HBsAg. HBsAg expression was tested by RT-PCR and ELISA.

RESULTS

HBsAg was expressed variously in the eukaryotic cells mentioned above. HBsAg (A value) of the cell supernatants (48 h) were 0.92, 0.09, 0.47, respectively.

CONCLUSION

The vector used in this study is an effective one to carry genes of interest to target cells and it may be useful in the test for gene therapy.

[Resistance of Bcl-2 adenovirus vector to HepG(2) cell apoptosis induced by ethanol]

OBJECTIVE

To evaluate the role of Bcl-2 family proteins in hepatocytic apoptosis caused by ethanol.

METHODS

We induced hepatocytic apoptosis in HepG(2) cells with ethanol and detected the apoptosis with TUNEL assay. Bcl-2, Bax, and Bak protein expression in the hepatocytes was determined by immunohistochemistry method. We also observed the expression of Bcl-2 protein in HepG(2) cells infected with Bcl-2 adenovirus vector and its protection against hepatocytic apoptosis caused by ethanol.

RESULTS

No obvious cytotoxicity was noted in 0.2% and 1% ethanol treatment group, while it developed in 3% ethanol treatment group and accompanied by a marked expression of Bax, Bak proteins.

CONCLUSION

The overexpression of Bax, Bak proteins may play a role in HepG(2) cell apoptosis induced by ethanol and can be blocked effectively by Bcl-2 adenovirus vector.

[The effects of sodium nitroprusside-induced hypotension at different levels on cerebral blood flow and metabolism: a clinical study]

OBJECTIVE

The clinical experiment was designed for observing the effects of deliberate hypotension at different level on cerebral blood flow and metabolism.

METHODS

30 ASA Grade I-II patients were randomly allocated to one of three groups (each group n = 10). Hypotension was induced by sodium nitroprusside in group 1[mean arterial pressure (MAP) = 55 mmHg] and group 2 (MAP = 65 mmHg). Group 3 (control) was on normotension. The changes of cerebral blood flow during hypotension were estimated according to the variability of cerebral blood flow velocity (CBFV) in the middle cerebral artery(MCA), which was obtained through transcranial Doppler ultrasonography (TCD).

RESULTS

Hypotension caused a moderate decrease in CBFV, but no significant difference, in CBFV and oxygen saturation in internal jugular vein(SjO2), either among three groups or during the procedure.

CONCLUSIONS

It is safe for cerebral perfusion and metabolism with deliberate hypotension at MAP = 55 mmHg.

[Effects of hepatitis B virus X gene on apoptosis and the activity of telomerase in HepG(2) cells]

OBJECTIVE

To observe the effects of hepatitis B virus X gene on hepatic carcinoma.

METHODS

The expression vectors of HBs gene and HBc gene (pCEP4-S and pCEP4-C) were transfected into HepG(2) cells by electroporation technique, and the cells, HepG(2) cells which contained the expression vectors of HBs (pCEP4-X) were recovered and cultured stably. The activity index of telomerase and the apoptosis rates in three cell lines were determined by PCR-ELISA and flow cytometry.

RESULTS

The 39.50% of cells expressed HBx gene came into S-phase of cell cycle, and the activity index of telomerase was higher in the cell line (3.95 +/- 0.07) than in other cell lines and control (F=20.85, P<0.01; d'=2.15, P<0.05) after synchronized culture. Induced by antisense oligonucleotides against telomerase the apoptosis of cell line expressed HBx gene reduced (apoptosis rate: 1.75%). The activity of cells also reduced with the dose increase of the antisense oligonucleotides and it showed a dose-response relationship.

CONCLUSION

The activity of HepG(2) cell can be increased and the cell apoptosis can be reduced by HBx gene. It may be another malignant process of hepatocytes.

Relationship between serum or tissue ouabain and blood pressure in 1k1c hypertensive rats

OBJECTIVE

To evaluate the role of endogenous ouabain (EO) in the development of hypertension and the characteristics of EO secretion in 1k1c (one kidney, one clipped) hypertensive rats.

METHODS

EO content of serum and tissues in 1k1c hypertensive rats and normal control Sprague-Dawley (SD) rats was detected by the method of enzyme linked immunosorbent assay (ELISA). The relationship between serum or tissue ouabain and blood pressure was analyzed in 1k1c hypertensive rats.

RESULTS

The ouabain content of serum, heart, kidney, adrenal gland, pituitary and hypothalamus was significantly higher in 1k1c hypertensive rats than that in normal control SD rats (2.25, 2.63, 3.35, 40.37, 3.34, 15.7 micrograms/kg tissue in 1k1c hypertensive rats vs 1.12, 1.79, 1.73, 27.54, 1.83, 10.10 micrograms/kg tissue in control SD rats, respectively. P < 0.05 for all of these comparisons). The ouabain content of the adrenal gland and the hypothalamus was higher than that of other tissues or serum, both in 1k1c rats and in control SD rats. The EO content of serum, kidney and hypothalamus was significantly correlated with blood pressure in 1k1c hypertensive rats (r = 0.59, 0.63, 0.52, respectively. P < 0.05). The ouabain content of heart, liver, adrenal gland and pituitary was not correlated with blood pressure.

CONCLUSIONS

EO might play an important role in the development of hypertension in 1k1c hypertensive rats. The adrenal gland may be a major source of EO and the hypothalamus-pituitary-adrenal axis may be involved in the regulation of EO secretion.

[Concept of ecosystem management and its essential elements]

Ecosystem management originates from the tradition fields of natural resources management and utilization, and develops in the 1990's. Based on our best understanding of the ecosystem composition, structure and function, and in definite spatiotemporal scales, it integrates human values and social-economic principles into managing ecosystems to resotre and/or sustain ecosystem integrity and sustainability. Ecosystem management requires the collection of field data and the monitoring of ecosystem dynamics at multiple scales. The essential elements of ecosystem management include clear management goals, definite ecological boundaries and units, sound ecological understanding, appropriate scale and hierarchic structure, understanding of ecosystem uncertainty, adaptive management, cooperation between agency and individuals, and viewing human and its value as ecosystem components. The goal of ecosystem management focuses on ecosystem sustainbility.

Hepatitis B virus X protein activates expression of IGF-IR and VEGF in hepatocellular carcinoma cells

OBJECTIVE

The expression of insulin-like growth factor I receptor (IGF-IR) and the vascular endothelial growth factor (VEGF) in HepG(2) cells transfected with a hepatitis B virus X (HBx) expression vector was investigated in an attempt to study their possible relationship to the growth of HBx-induced hepatocellular carcinoma (HCC).

METHODS

The eucaryotic expression vector of HBx gene was constructed and introduced into HepG(2) cells. The modified cell HepaG(2)-X was synchronized in a quiescent state by culture of serum deprivation. The IGF-IR and VEGF were analyzed by immunohistochemical and Western blot technique.

RESULTS

The positive rate of IGF-IR expression was 84%A3% in the transfected HBx gene cells, 26%A4% in X(0) control cells. The positive rate of VEGF expressed x cells was 83%A5%, X(0) cells was 28%A6% (P<0.001). The level of IGF-IR and VEGF in serum-starved x modified cells was 1.5 times higher than that of synchronized X(0) modified cells.

CONCLUSION

Since the IGF-IR is a very important growth factor in sustaining the tumor abnormal growth and the VEGF has a crucial role in inducting tumor angiogenesis, our findings indicate that HBx may play an important role in the processes of HCC by activating IGF-IR and VEGF gene expression.

Automated parallel DNA sequencing on multiple channel microchips

We report automated DNA sequencing in 16-channel microchips. A microchip prefilled with sieving matrix is aligned on a heating plate affixed to a movable platform. Samples are loaded into sample reservoirs by using an eight-tip pipetting device, and the chip is docked with an array of electrodes in the focal plane of a four-color scanning detection system. Under computer control, high voltage is applied to the appropriate reservoirs in a programmed sequence that injects and separates the DNA samples. An integrated four-color confocal fluorescent detector automatically scans all 16 channels. The system routinely yields more than 450 bases in 15 min in all 16 channels. In the best case using an automated base-calling program, 543 bases have been called at an accuracy of >99%. Separations, including automated chip loading and sample injection, normally are completed in less than 18 min. The advantages of DNA sequencing on capillary electrophoresis chips include uniform signal intensity and tolerance of high DNA template concentration. To understand the fundamentals of these unique features we developed a theoretical treatment of cross-channel chip injection that we call the differential concentration effect. We present experimental evidence consistent with the predictions of the theory.

Substitution of betaGlu(201) in the alpha(3)beta(3)gamma subcomplex of the F(1)-ATPase from the thermophilic Bacillus PS3 increases the affinity of catalytic sites for nucleotides

In the crystal structure of bovine mitochondrial F(1)-ATPase (MF(1)) (Abrahams, J. P., Leslie, A. G. W., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628), the side chain oxygen of betaThr(163) interacts directly with Mg(2+) coordinated to 5'-adenylyl beta, gamma-imidodiphosphate or ADP bound to catalytic sites of beta subunits present in closed conformations. In the unliganded beta subunit present in an open conformation, the hydroxyl of betaThr(163) is hydrogen-bonded to the carboxylate of betaGlu(199). Substitution of betaGlu(201) (equivalent to betaGlu(199) in MF(1)) in the alpha(3)beta(3)gamma subcomplex of the F(1)-ATPase from the thermophilic Bacillus PS3 with cysteine or valine increases the propensity to entrap inhibitory MgADP in a catalytic site during hydrolysis of 50 microM ATP. These substitutions lower K(m3) (the Michaelis constant for trisite ATP hydrolysis) relative to that of the wild type by 25- and 10-fold, respectively. Fluorescence quenching of alpha(3)(betaE201C/Y341W)(3)gamma and alpha(3)(betaY341W)(3)gamma mutant subcomplexes showed that MgATP and MgADP bind to the third catalytic site of the double mutant with 8.4- and 4.4-fold higher affinity, respectively, than to the single mutant. These comparisons support the hypothesis that the hydrogen bond observed between the side chains of betaThr(163) and betaGlu(199) in the unliganded catalytic site in the crystal structure of MF(1) stabilizes the open conformation of the catalytic site during ATP hydrolysis.

Inhibition of polyglutamine protein aggregation and cell death by novel peptides identified by phage display screening

Proteins with expanded polyglutamine domains cause eight inherited neurodegenerative diseases, including Huntington's, but the molecular mechanism(s) responsible for neuronal degeneration are not yet established. Expanded polyglutamine domain proteins possess properties that distinguish them from the same proteins with shorter glutamine repeats. Unlike proteins with short polyglutamine domains, proteins with expanded polyglutamine domains display unique protein interactions, form intracellular aggregates, and adopt a novel conformation that can be recognized by monoclonal antibodies. Any of these polyglutamine length-dependent properties could be responsible for the pathogenic effects of expanded polyglutamine proteins. To identify peptides that interfere with pathogenic polyglutamine interactions, we screened a combinatorial peptide library expressed on M13 phage pIII protein to identify peptides that preferentially bind pathologic-length polyglutamine domains. We identified six tryptophan-rich peptides that preferentially bind pathologic-length polyglutamine domain proteins. Polyglutamine-binding peptide 1 (QBP1) potently inhibits polyglutamine protein aggregation in an in vitro assay, while a scrambled sequence has no effect on aggregation. QBP1 and a tandem repeat of QBP1 also inhibit aggregation of polyglutamine-yellow fluorescent fusion protein in transfected COS-7 cells. Expression of QBP1 potently inhibits polyglutamine-induced cell death. Selective inhibition of pathologic interactions of expanded polyglutamine domains with themselves or other proteins may be a useful strategy for preventing disease onset or for slowing progression of the polyglutamine repeat diseases.

Migration time correction for the analysis of derivatized amino acids and oligosaccharides by micellar capillary electrochromatography

Migration-time reproducibility is essential in the use of capillary electrophoresis to identify components in mixtures. Two methods based on the migration time of either one or two reference markers are proposed for improving migration time reproducibility. These methods were evaluated to determine the migration time reproducibility for phenylthiohydantoin-amino acids, fluorescein thiohydantoin-amino acids, and tetramethylrhodamine labeled oligosaccharides. In the best case, the relative standard deviation of the migration time was reduced from >3% without correction to <0.04% with the two-marker correction.

A multiple-capillary electrophoresis system for small-scale DNA sequencing and analysis

A five-capillary system has been developed for DNA sequencing and analysis. The post-column fluorescence detector is based on a sheath-flow cuvette. The instrument provides uniform and continuous illumination of the samples. The cuvette virtually eliminates cross-talk in the fluorescence signal between capillaries. Discrete single-photon counting avalanche photodiodes provide high efficiency light detection. The instrument has detection limits (3sigma) of 130 +/- 30 fluorescein molecules injected onto each capillary. Over 650 bases of sequence at 98.8% accuracy were generated in 100 min at 50 degrees C from M13mp18. Separation and detection of short tandem repeats proved efficient and accurate with the use of internal standards for direct comparison of migration times between capillaries.

Length of protection by murine vaccination with living infective third-stage hookworm larvae

OBJECTIVE

To determine the length of protection by murine immunization with living third-stage hookworm larvae (L3) as measured by reduction in worm burden and host serologic antibody responses.

METHODS

Outbred male (Kunming strain) mice were immunized subcutaneously with 500 L3 once every 2 weeks for a total of immunization for 3 times, and then challenged orally with 1000 L3 for 1 to 8 weeks after the final immunization. Host protective immunity was determined both by the reduction in worm burden as measured by the number of L3 recovered from murine lungs 48-hour post-challenge, as well as by measurement of circulating antibodies. Histopathological responses were also examined. Non-immunized mice served as negative controls.

RESULTS

The protection by L3 immunization declined over time. One or 2 weeks after the final immunization, worm burdens were reduced 72% and 77.5% after challenge respectively. In contrast, only 37% reduction in worm burden was observed when the L3 challenge was delayed by 4 weeks and protection was almost entirely lost when there was an 8 week delay between the time of final immunization and challenge. The reduced level of protection over time partially correlated with diminishing L3-specific antibody responses. Host inflammation in the lungs of immunized mice also diminished.

CONCLUSION

The protection afforded by living L3 immunization is maximal for the first two weeks after immunization, but then declines significantly over the ensuing weeks.

Cutaneous and subcutaneous mast cell and eosinophil responses after challenge in mice vaccinated with living infective third-stage hookworm larvae

OBJECTIVE

To examine the quantitative and qualitative alterations in mast cells and eosinophils distributed in the cutaneous and subcutaneous tissues of hookworm-infected, uninfected and vaccinated mice.

METHODS

Outbred male Kunming strain mice, weighing 18-22 g, were vaccinated thrice by subcutaneous inoculation with 500 living third-stage infective larvae (L3) of Ancylostoma caninum (A. caninum) every 2 weeks, and then challenged subcutaneously with 500 L3 one week after the final immunization. Uninfected mice and non-immunized mice but infected with L3 served as controls. The abdominal skin at the site of percutaneous entry was excised from challenged mice at intervals between 6 hours and 7 days after challenge, fixed, and then examined by light microscopy after staining with either toluidine blue or hematoxylin and eosin.

RESULTS

The total number of mast cells appearing in cutaneous, and subcutaneous tissues, and underlying abdominal musculature of immunized mice increased significantly compared with non-immunized mice. Mast cells from hookworm-infected mice showed evidence of membrane rupture and degranulation in contrast to the intact appearance of mast cells from uninfected mice. The degree of mast cell degranulation was greater in vaccinated and challenged mice when compared with non-immunized and infected mice. Similarly, eosinophilic infiltration was greatly enhanced after L3 infection. Tissues from vaccinated mice had a greater number of eosinophils than non-immunized mice after infection.

CONCLUSIONS

Mast cell alterations appearing earlier than tissue eosinophilic infiltration is major inflammatory response to Ancylostoma caninum (A. caninum) L3 infection in mice. These processes are more obvious in L3-vaccinated mice.

Oxidation of the alpha(3)(betaD311C/R333C)(3)gamma subcomplex of the thermophilic Bacillus PS3 F(1)-ATPase indicates that only two beta subunits can exist in the closed conformation simultaneously

In the crystal structure of the bovine heart mitochondrial F(1)-ATPase (Abrahams, J. P., Leslie, A. G. W., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628), the two liganded beta subunits, one with MgAMP-PNP bound to the catalytic site (beta(T)) and the other with MgADP bound (beta(D)) have closed conformations. The empty beta subunit (beta(E)) has an open conformation. In beta(T) and beta(D), the distance between the carboxylate of beta-Asp(315) and the guanidinium of beta-Arg(337) is 3.0-4.0 A. These side chains are at least 10 A apart in beta(E). The alpha(3)(betaD311C/R333C)(3)gamma subcomplex of TF(1) with the corresponding residues substituted with cysteine has very low ATPase activity unless it is reduced prior to assay or assayed in the presence of dithiothreitol. The reduced subcomplex hydrolyzes ATP at 50% the rate of wild-type and is rapidly inactivated by oxidation by CuCl(2) with or without magnesium nucleotides bound to catalytic sites. Titration of the subcomplex with iodo[(14)C]acetamide after prolonged treatment with CuCl(2) in the presence or absence of 1 mM MgADP revealed nearly two free sulfhydryl groups/mol of enzyme. Therefore, one pair of introduced cysteines is located on a beta subunit that exists in the open or partially open conformation even when catalytic sites are saturated with MgADP. Since V(max) of ATP hydrolysis is attained when three catalytic sites of F(1) are saturated, the catalytic site that binds ATP must be closing as the catalytic site that releases products is opening.

[Production of HBV surface antigen-specific target cell]

OBJECTIVE

To analyze the hepatitis B virus surface antigen (HBsAg)-specific cytotoxic T-cell (CTL) response during hepatitis development and investigate the effect of some factors on CTL response.

METHODS

The recombinant retrovirus plasmid PLXSN-S was tranferred into PA317 by electroporation and the pseudoviruses produced from PA317 were used to infect EL4. Clones which highly expressed HBsAg were selected with limited dilution.

RESULTS

A clone expressing-HBsAg the highest (A = 0.85 in supernatant at 48th hour) was obtained which steadly expressed HBsAg in vitro after at least 100 passages. It worked very well when used as target cells in CTL response after C57 mice immunized with PLXSN-S and recombinant adenovirus vector (rAdv-B7-2-S).

CONCLUSION

We constructed HBsAg-specific target cell line which steadly expressed HBsAg. It may play an important role in HBsAg CTL response and immunopathogenetic mechanisms of hepatitis B.

Separating DNA sequencing fragments without a sieving matrix

The possibility of separating appropriately labeled DNA fragments using free-flow capillary electrophoresis was predicted a few years ago based on simple theoretical arguments. Free-flow separation of double-stranded DNA (dsDNA) fragments in the 100-1000 base range was later demonstrated using a streptavidin label. In this article, we now report that end-labeled free-flow electrophoresis (ELFSE) can also be used to sequence single-stranded DNA (ssDNA). The first 100 bases of a DNA sequencing reaction were read without any sieving matrix when fractionated streptavidin was added to the 5'-end of the ssDNA fragments. These separations required only 18 min and did not require coated capillaries. An analysis of the results indicates that sample injection, analyte-wall interactions and thermal diffusion are the limiting factors at this time. Extrapolating from our data, we predict that several hundred bases could be sequenced in less than 30 min with the proper conditions. ELFSE thus offers an attractive potential alternative to polymer solutions for DNA sequencing in capillaries and microchips.