Accuracy of stroke volume variation and pulse pressure variation to predict fluid responsiveness in patients with thoracic kyphosis.

BACKGROUND: This study aims to evaluate the ability of stroke volume variation (SVV) and pulse pressure variation (PPV) to predict fluid responsiveness in mechanically ventilated patients with thoracic kyphosis. METHODS: A total of 35 patients diagnosed with thoracic kyphosis undergoing corrective surgery were studied. For all patients, the Vigileo/FloTrac system was used for analysis. Hemodynamic data such as mean arterial pressure (MAP), heart rate (HR), stroke volume (SV), stroke volume index (SVI), cardiac output (CO), cardiac output index (CI), SVV, and PPV were recorded before and after volume expansion (VE). Fluid responsiveness was defined as an increase in SVI ≥10% (ΔSVI ≥10%). Patients were divided into responders and non-responders as determined by changes in ΔSVI ≥10% and <10%. Nonparametric Wilcoxon rank sum test was used to compare the hemodynamic parameters of Responders and Non-responders before and after VE. Pearson correlation analysis was used to analyze the values of SVV, PPV and ΔSVI. The receiver operating characteristic (ROC) curve of each hemodynamic index was drawn to determine its accuracy and threshold. RESULTS: Two patients were excluded. There was no significant difference in patients' characteristics between Responders and Non-responders. After VE, there were no significant changes in HR, MAP, and SV in both responders and non-responders, but CI were significantly changed in the two groups. SVI and CO increased significantly in responders before and after VE, but not in non-responders. VE also caused decreases of PPV and SVV in both responders and non-responders. Before VE, the SVV and PPV correlated with ΔSVI in responders (r=0.621, r=0.569, respectively, P<0.05), but neither the SVV nor PPV correlated with ΔSVI in non-responders (P>0.05). The areas under the ROC curves of patients with thoracic kyphosis were 0.872 (95% CI: 0.719-1.000) for SVV and 0.833 (95% CI: 0.667-1.000) for PPV. The threshold of the SVV of patients with thoracic kyphosis was 13.5%, and the threshold of PPV was 14.5%. CONCLUSIONS: Both SVV and PPV can be used as effective indictors to monitor volume changes in patients with thoracic kyphosis.

Guest Sequence Can Influence RNA Encapsulation by an Engineered Cationic Protein Capsid.

Specific encapsulation of RNA in a cell is a challenging molecular recognition problem that has important implications for virology and drug delivery. An engineered variant of the Aquifex aeolicus lumazine synthase capsid that possesses a positively supercharged interior (AaLS-pos) has previously been shown to encapsulate a mixture of cellular RNAs in bacteria via charge complementarity. To investigate the influence of nucleotide sequence on encapsulation, eight reporter RNAs with the same charge but with highly diverse arbitrary sequence regions (ASRs) were coproduced with AaLS-pos in Escherichia coli cells. The ASRs cause significant differences in the yields of encapsulated full-length reporter RNA, measured by q-RT-PCR. Four of the reporters also have the Broccoli-F30 aptamer, which hinders encapsulation compared with reporters with an alternative sequence in place of Broccoli-F30. In all, the encapsulation yield of the best reporter was ∼200 times higher than the worst. The reporters also differed by up to ∼28 000 times in their partitioning between the capsid and the bulk cellular environment, with those lacking Broccoli-F30 showing higher enrichments in AaLS-pos. The detection of Broccoli-F30 by a fluorescence assay showed higher levels than that determined by q-RT-PCR, suggesting that partially degraded forms of the reporters are encapsulated more frequently than the full-length versions. For the reporters lacking the Broccoli-F30 aptamer, the encapsulation yield shows inverse correlations with both their expression levels and the predicted secondary structural stabilities of their ASRs. These observations suggest that in this system, guest selection depends on the RNA flexibility and the shape complementarity with the capsid.

[Chiral separation of fourteen amino alcohols by nonaqueous capillary electrophoresis].

We developed a new method for chiral separation of fourteen amino alcohols by nonaqueous capillary electrophoresis (NACE) with the D-(+)-gluconic acid δ-lactone-boric acid complex as chiral selector. In order to achieve good enantioseparation, the effects of D-(+)-gluconic acid δ-lactone and boric acid concentrations, triethylamine concentration, as well as capillary temperature were systematically investigated. The optimized conditions were identified as follows: an uncoated fused silica capillary of 50 µm ID with a total length (L(tot)) of 55 cm and an effective length (L(eff)) of 45 cm; 200 mmol·L(-1) D-(+)-gluconic acid δ-lactone, 80 mmol·L(-1) boric acid, and 57.4 mmol·L(-1) triethylamine in methanol; positive pressure injection at 2.9 psi for 2 s; capillary temperature, 25 ± 0.2 ℃; applied voltage, +15 k V; detection wavelength, 214 nm. Under the optimized conditions, a good chiral resolution was achieved in most of the tested drugs. This method provides a foundation for the development and application of new chiral selectors of polyhydroxy compound-boric acid complexes in chiral drugs analysis by NACE.

Cytotoxicity and apoptosis induced by nanobacteria in human breast cancer cells.

BACKGROUND: The existing evidence that nanobacteria (NB) are closely associated with human disease is overwhelming. However, their potential toxicity against cancer cells has not yet been reported. The objective of this study was to investigate the cytotoxic effects of NB and nanohydroxyapatites (nHAPs) against human breast cancer cells and to elucidate the mechanisms of action underlying their cytotoxicity. METHODOLOGY/PRINCIPAL FINDINGS: NB were isolated from calcified placental tissue, and nHAPs were artificially synthesized. The viability of the MDA-MB-231 human breast cancer cell line was tested by using the Kit-8 cell counting kit assay. Apoptosis was examined by transmission electron microscopy and flow cytometry. The endocytosis of NB and nHAPs by MDA-MB-231 cells was initially confirmed by microscopy. Although both NB and nHAPs significantly decreased MDA-MB-231 cell viability and increased the population of apoptotic cells, NB were more potent than nHAPs. After 72 hours, NB also caused ultrastructural changes typical of apoptosis, such as chromatin condensation, nuclear fragmentation, nuclear dissolution, mitochondrial swelling, and the formation of apoptotic bodies. CONCLUSION/SIGNIFICANCE: In MDA-MB-231 human breast cancer cells, NB and nHAPs exerted cytotoxic effects that were associated with the induction of apoptosis. The effects exerted by NB were more potent than those induced by nHAPs. NB cytotoxicity probably emerged from toxic metabolites or protein components, rather than merely the hydroxyapatite shells. NB divided during culturing, and similar to cells undergoing binary fission, many NB particles were observed in culture by transmission electron microscopy, suggesting they are live microorganisms.