[Impact of adaptive positive end expiratory pressure and mechanical ventilation on hemodynamics and oxygen kinetics in post-liver transplantation patients].

OBJECTIVE: To determine the impact of adaptive positive end expiratory pressure (PEEP) and mechanical ventilation on hemodynamics and oxygen kinetics in post-liver transplantation patients. METHODS: The study included 11 patients who accepted mechanical ventilation after piggyback liver transplantation. Swan-Ganz catheter and radial artery catheter were used to monitor the cardiac output (CO), mean pulmonary arterial pressure (MPAP), mean arterial blood pressure (MABP) and central venous pressure (CVP) and airway pressure. After transplantation, PEEP of 0, 5, 10 and 15 cm H(2)O (1 cm H(2)O=0.098 kPa) was instituted to support the ventilation alternately. After 30 minutes, pressure regulated volume controlled ventilation (PRVCV) and pressure controlled synchronized intermittent mandatory ventilation+pressure support ventilation (PC-SIMV+PSV) were used to support the ventilation alternately and the indexes of hemodynamics and oxygen kinetics were analyzed. RESULTS: The data showed that differences existed in peak airway pressure, mean airway pressure, CVP and MPAP when different levels of PEEP were used. These indexes were significantly higher in PEEP of 15 and 10 cm H(2)O than those in PEEP of 0 and 5 cm H(2)O.There were no differences in pH, partial pressure of carbon dioxide in arterial blood (PaCO(2)), pressure of oxygen in arterial blood (PaO(2)), arterial oxygen saturation (SaO(2)), oxygen delivery (DO(2)), oxygen consumption (VO(2)) and oxygen extraction rate (O(2)ER) at different levels of PEEP. The airway pressure was significantly lower under PRVCV pattern than those under PC-SIMV+PSV pattern [(8.78+/-1.53) cm H(2)O vs. (11.64+/-3.30) cm H(2)O, P<0.05]. There were no differences in other indexes between these two mechanical ventilation patterns. CONCLUSION: These date suggested that a low level of PEEP (5 cm H(2)O) during mechanical ventilation should be used in post-liver transplantation patients in order to decrease the influence of PEEP on systemic circulation and hepatic regurgitation. PRVCV could be a more suitable mechanical ventilation pattern for patient after liver transplantation.

A novel hepatitis B virus genotyping system by using restriction fragment length polymorphism patterns of S gene amplicons.

AIM: Traditional hepatitis B virus (HBV) genotyping methods using restriction fragment length polymorphism (RFLP) can reliably identify genotypes A to F. As HBV genotypes G and H have been recently identified, this study was to establish an accurate and simple genotyping method for all eight HBV genotypes (A to H). METHODS: Two hundred and forty HBV small S sequences obtained from GeneBank were analysed for restriction enzyme sites that would be genotype-specific. Restriction patterns following digestion with restriction enzymes BsrI, StyI, DpnI, HpaII, and EaeI, were determined to identify all eight HBV genotypes. Mixed genotype infections were confirmed by cloning and further RFLP analysis. RESULTS: The new genotyping method could identify HBV genotypes A to H. Genotypes B and C could be determined by a single step digestion with BsrI and StyI in parallel. This was particularly useful in the Far East where genotypes B and C are predominant. Serum samples from 187 Chinese HBV carriers were analysed with this genotyping system, and the genotype distribution was 1.1% (2), 51.9% (97), 40.6% (76) and 4.8% (9) for genotypes A, B, C, and D, respectively. Mixed genotypes were found in only 3 patients (1.6%). Sequence data analysis confirmed the validity of this new method. CONCLUSION: This HBV genotyping system can identify all eight HBV genotypes. It is accurate and simple, and can be widely used for studies on HBV genotyping.

[Hepatitis B virus genotypes and the heterogeneity of its polymerase gene].

OBJECTIVE: To study the heterogeneity of polymerase gene (P gene) within hepatitis B virus (HBV) genotypes based on a systematic analysis of 202 HBV P genes, providing some useful references for further studies on the relationship among HBV genotypes, P gene mutations, replication and nucleoside analogues drug-resistance. METHODS: 202 HBV complete sequences containing P genes were obtained from GenBank and were analysed using computer softwares. RESULTS: There were some genotype-related characteristics of HBV P genes. As reverse transcriptase domain was concerned, there were more amino acid divergences in genotype C and D compared with these in genotype A. There were also amino acid substitutions in the A-F conserved regions of the reverse transcriptase domain within and between HBV genotypes. CONCLUSIONS: There are divergences of P genes and amino acids within and between HBV genotypes, which should be considered when amino acid changes are analyzed whether they are proposed to be drug-resistance mutations or the results from quasispecies-selected. Moreover, these divergences may affect the antiviral effect of nucleoside analogues on HBV with different genotypes.