ABSTRACT
Objective To use a simple bedside technique to verify the pathophysiological mechanism of pulmonary hypertension (PH) in different races. Method The Valsalva maneuver (VM) was performed in patients referred to a specialty PH clinic. The blood pressure response of patients to VM was in different fashions. The blood pressure (BP) was measured by using cuff and stethoscope. When the cuff was inflated to 15 mmHg above the systolic pressure, sound could be heard by auscultation during VM and when the cuff was deflated the sound disappeared over 3 heart beats which was considered as abnormal BP response, and less than 3 heart beats defined as normal BP response. The right heart catheterization in patients with PH as a part of the standard evaluation. Results This study included 84 patients with a mean age of (63 ± 16) years. Those with abnormal BP response to VM had higher pulmonary artery wedge pressure (PAWP) [(22.5±6.6) vs. (11.9±4.3) mmHg, P ＜0.0001] and lower pulmonary vascular resistance [(5.8 ± 4.0) vs. (8.1 ± 4.6 ) WU, P = 0.01]. Blood pressure response to VM did not correlate with mean pulmonary artery (PA) pressure [(46.2 ± 9.9) vs. (43.4 ±10.4) mmHg, P =0.20] or cardiac index (both 2.4 ± 0.6 L/min/m2). The abnormal BP response to VM had high sensitivity (89.4%), specificity (86.1%) and accuracy (86.9%) for determining PAWP＞ 15 mmHg.Conclusions BP response to Valsalva maneuver provides important information about left heart filling pressures in patients with PH.
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Objective To construct Streptococcus mutans UA159 mutants with deletion of LuxS gene related to quorum-sensing pathway and evaluate the aciduricity of the mutants. Methods Using S. mutans UA159 as materials, the PCR fragments of the upstream and downstream regions of LuxS and erythromycin resistance(Eymr) gene of PJT10 were cloned into plasmid PUC19. The resulting constructs were integrated into the chromosome of S. mutans. LuxS gene deletion mutant was then constructed in S. mutans by means of allelic exchange and selected for resistance to erythromycin. The aciduric ability of the mutant under different pH was measured and S. mutans UA159 was used as control. Results The LuxS-deleted status of S. mutans mutants were confirmed by various PCR and DNA sequencing. The results showed that Eymr gene take the place of LuxS gene, while the mutant can not induce bioluminescenece. The LuxS mutant strain displayed a decreased growth ability with the decreasing pH values compared to those of the wild-type strain UA159. Conclusion A LuxS-negative mutants of S. mutans is constructed. The LuxS quorum sensing system is involved in the regulation of aciduricity of S. mutans UA159.
ABSTRACT
Objective To knock out the entire LuxS gene of Streptococcus mutans UA159 strain via homologous recombination and construct a LuxS-deleted mutant strain of S.mutans.Methods The erythromycin resistance gene(Eymr)was inserted between the two DNA fragments located in the upper and downstream of LuxS gene that had been amplified by PCR.Then the two DNA fragments along with the inserted Eymr were engineered into pUCl9 plasmid to construct the recombination plasmid pUCluxKO.Electrotransformation of S. mutans cells with pUCluxKO-mutant resulted in the isolation of erythromycin resistant S.mutans,transformants,which was then subjected to polymerase chain reaction,Vibrio harveyi BBl70 luminescence bioassay and sequencing analysis.Results Restriction endonuclease analysis showed that pUCluxKOmutant vector had been successfully recombined.The deletion of LuxS of S. mutans mutants was confirmed bv PCR with primers specific for the genes of LuxS and the erythromycin resistance.S.mutans mutant could not induce bioluminescence.indicating the mutant had been successfully recombined.The constructed Chinese S.mutans showed good stability after 20 generations of cultivation.Conclusion The S.mutans gene allelic exchange plasmid is constructed correctively and a LuxS-negative mutant of S.mutans has been constructed.which can be helpful for further study of the role of LuxS in the pathogenesis of S.mutans.
ABSTRACT
<p><b>BACKGROUND</b>To evaluate the significance of flow cytometry (FCM) in the analysis of multi-drug resistance of doxorubicin.</p><p><b>METHODS</b>The level of doxorubicin or Rh-123 in S-180R and BGC-823/DOX, which were two cell lines with different drug resistance, was measured by FCM comparatively and continuously.</p><p><b>RESULTS</b>The total fluorescence profile peaks of S-180R, a high resistant cell line, were predominantly different from those of S-180, the parent cell line, by the FCM analysis. The subtle fluorescence profile differences between BGC-823/DOX (a low resistant cell line) and the parent cell line were quantitatively measured on the FCM map. The changes of each resistant cell fluorescence from the S 180R cells could be displayed by continuous tests, the more near the fluorescence level of each cell was, the more the fluorescence pike of whole cells centralized.</p><p><b>CONCLUSIONS</b>FCM is a sensitive, accurate and quantitative test in the analysis of doxorubicin drug resistance.</p>