Evolutionary dynamics and temporal/geographical correlates of recombination in the human enterovirus echovirus types 9, 11, and 30.

The relationship between virus evolution and recombination in species B human enteroviruses was investigated through large-scale genetic analysis of echovirus type 9 (E9) and E11 isolates (n = 85 and 116) from 16 European, African, and Asian countries between 1995 and 2008. Cluster 1 E9 isolates and genotype D5 and A E11 isolates showed evidence of frequent recombination between the VP1 and 3Dpol regions, the latter falling into 23 (E9) and 43 (E11) clades interspersed phylogenetically with 46 3Dpol clades of E30 and with those of other species B serotypes. Remarkably, only 2 of the 112 3Dpol clades were shared by more than one serotype (E11 and E30), demonstrating an extremely large and genetically heterogeneous recombination pool of species B nonstructural-region variants. The likelihood of recombination increased with geographical separation and time, and both were correlated with VP1 divergence, whose substitution rates allowed recombination half-lives of 1.3, 9.8, and 3.1 years, respectively, for E9, E11, and E30 to be calculated. These marked differences in recombination dynamics matched epidemiological patterns of periodic epidemic cycles of 2 to 3 (E9) and 5 to 6 (E30) years and the longer-term endemic pattern of E11 infections. Phylotemporal analysis using a Bayesian Markov chain Monte Carlo method, which placed recombination events within the evolutionary reconstruction of VP1, showed a close relationship with VP1 lineage expansion, with defined recombination events that correlated with their epidemiological periodicity. Whether recombination events contribute directly to changes in transmissibility that drive epidemic behavior or occur stochastically during periodic population bottlenecks is an unresolved issue vital to future understanding of enterovirus molecular epidemiology and pathogenesis.

Plaque and growth characteristics of different polioviruses isolated from acute flaccid paralysis in Northern Nigeria.

OBJECTIVE: To determine some virulent trait-related properties of poliovirus isolates from children with acute flaccid paralysis following vaccination with oral polio vaccine (OPV). DESIGN: Six polioviruses earlier characterised into wild, vaccine-derived and OPV-like were studied using the plaque morphology and growth kinetics at supra-optimal temperature. SETTING: Department of Virology, University of Ibadan, Nigeria. SUBJECTS: Polio isolates from six children who developed acute flaccid paralysis following vaccinations with various doses of OPV were used. All the children were located in the Northern part of the country where poliovirus is still circulating. MAIN OUTCOME MEASURES: The two vaccine-derived polioviruses acquired wild type characteristics. RESULTS: All the six poliovirus isolates developed different forms of plaques ranging from tiny, small and large. The plaque formed could however not be used to identify the different isolates. Growth of the different isolates at supra-optimal temperature showed that the three wild polioviruses grew to a higher titre when compared with the Sabin 2 control. The two vaccine derived isolates behaved like the wild poliovirus while the OPV-like virus acquired an intermediate characteristics between wild and sabin. CONCLUSION: The wild polioviruses represented in this study are among the last vestiges of the circulating polioviruses found in the world. It is possible that the observed biological properties of wild types 1 and 3 described in the study are typical of the West African polioviruses. These properties will provide useful previews to the final identification of some important clinical isolates especially type 1 which may grow rapidly in cell culture.

Antibody response to 17D yellow fever vaccine in Ghanaian infants.

OBJECTIVES: To assess the seroresponses to yellow fever vaccination at 6 and 9 months of age; assess any possible adverse effects of immunization with the 17D yellow fever vaccine in infants, particularly at 6 months of age. METHODS: Four hundred and twenty infants who had completed BCG, OPV and DPT immunizations were randomized to receive yellow fever immunization at either 6 or 9 months. A single dose of 0.5 ml of the reconstituted vaccine was administered to each infant by subcutaneous injection. To determine the yellow fever antibody levels of the infants, each donated 1 ml whole blood prior to immunization and 3 months post-immunization. Each serum sample was titred on Vero cells against the vaccine virus. FINDINGS: The most common adverse reactions reported were fever, cough, diarrhoea and mild reactions at the inoculation site. The incidences of adverse reactions were not statistically different in both groups. None of the pre-immunization sera in both age groups had detectable yellow fever antibodies. Infants immunized at 6 months recorded seroconversion of 98.6% and those immunized at 9 months recorded 98% seroconversion. The GMT of their antibodies were 158.5 and 129.8, respectively. CONCLUSIONS: The results indicate that seroresponses to yellow fever immunization at 6 and 9 months as determined by seroconversion and GMTs of antibodies are similar. The findings of good seroresponses at 6 months without significant adverse effects would suggest that the 17D yellow fever vaccine could be recommended for use in children at 6 months in outbreak situations or in high risk endemic areas.

Cerebral autoregulation in subjects adapted and not adapted to high altitude.

BACKGROUND AND PURPOSE: Impaired cerebral autoregulation (CA) from high-altitude hypoxia may cause high-altitude cerebral edema in newcomers to a higher altitude. Furthermore, it is assumed that high-altitude natives have preserved CA. However, cerebral autoregulation has not been studied at altitude. METHODS: We studied CA in 10 subjects at sea level and in 9 Sherpas and 10 newcomers at an altitude of 4243 m by evaluating the effect of an increase of mean arterial blood pressure (MABP) with phenylephrine infusion on the blood flow velocity in the middle cerebral artery (Vmca), using transcranial Doppler. Theoretically, no change of Vmca in response to an increase in MABP would imply perfect autoregulation. Complete loss of autoregulation is present if Vmca changes proportionally with changes of MABP. RESULTS: In the sea-level group, at a relative MABP increase of 23+/-4% during phenylephrine infusion, relative Vmca did not change essentially from baseline Vmca (2+/-7%, P=0.36), which indicated intact autoregulation. In the Sherpa group, at a relative MABP increase of 29+/-7%, there was a uniform and significant increase of Vmca of 24+/-9% (P<0.0001) from baseline Vmca, which indicated loss of autoregulation. The newcomers showed large variations of Vmca in response to a relative MABP increase of 21+/-6%. Five subjects showed increases of Vmca of 22% to 35%, and 2 subjects showed decreases of Vmca of 21% and 23%. CONCLUSIONS: All Sherpas and the majority of the newcomers showed impaired CA. It indicates that an intact autoregulatory response to changes in blood pressure is probably not a hallmark of the normal human cerebral vasculature at altitude and that impaired CA does not play a major role in the occurrence of cerebral edema in newcomers to the altitude.

Response to local anaesthetic injection as a predictor of successful hip surgery.

AIM: To compare the outcome of hip therapy with the response to local anaesthetic into the hip. MATERIALS AND METHODS: A retrospective hip arthrographic study of 60 patients complaining of hip pain was performed. The average age of the patients was 58 +/- 20 years with ratio of men to women of 11:19. Thirty-eight of these patients underwent local anaesthetic intracapsular injection. Twenty-three (61%) obtained relief from pain whereas two (5%) experienced worsened pain. RESULTS: Of the 23 patients who experienced pain relief 17 (74%) had a positive post-operative course, in comparison with eight (44%) who had a positive post-operative course from the group where intra-articular local anaesthetic was not used. It was also noted that patients over 30 years of age had favourable post-operative results in the presence or absence of local anaesthetic testing. CONCLUSION: These results indicate that hip arthrography with a pain relieving intracapsular local anaesthetic injection, is a positive post-operative prognostic factor in a patient group of disparate disorders. A positive response to local anaesthetic injection into a hip may predict which patients are likely to respond well to surgery. We advise alterations to the consent procedure to add a warning concerning the small risk of increased hip pain. If further studies were to confirm our results it may be wise to recommend that local anaesthetic intracapsular injection and judgement of its efficacy should precede many surgical procedures involving the hip.

Jugular bulb oxygen saturation during propofol and isoflurane/nitrous oxide anesthesia in patients undergoing brain tumor surgery.

UNLABELLED: We investigated, in brain tumor patients, the jugular bulb venous oxygen partial pressure (PjO2) and hemoglobin saturation (SjO2), the arterial to jugular bulb venous oxygen content difference (AJDO2), and middle cerebral artery blood flow velocity (Vmca) during anesthesia, and the effect of hyperventilation on these variables. Twenty patients were randomized to receive either isoflurane/ nitrous oxide/fentanyl (Group 1) or propofol/fentanyl (Group 2). At normoventilation (PacO2 35 +/- 2 mm Hg in Group 1 and 33 +/- 3 mm Hg in Group 2), SjO2 and PjO2 were significantly higher in Group 1 than in Group 2 (SjO2 60% +/- 6% and 49% +/- 13%, respectively; P = 0.019) (PjO2 32 +/- 3 and 27 +/- 5 mm Hg, respectively; P = 0.027). In Group 2, 5 of 10 patients had SjO2 < 50%, and 3 of these patients had SjO2 < 40% and AJDO2 > 9 mL/dL. All patients in Group 1 had SjO2 > 50%. During hyperventilation, there were no differences in SjO2, PjO2, or AJDO2 between the two groups. On hyperventilation, there was no correlation between the relative decreases of Vmca and 1/AJDO2 (r = 0.21, P = 0.41). The results indicate during propofol anesthesia, half of the brain tumor patients showed signs of cerebral hypoperfusion, but not during isoflurane/nitrous oxide anesthesia. Furthermore, during PacO2 manipulations, shifts in Vmca are inadequate to evaluate brian oxygen delivery in these patients. IMPLICATIONS: During propofol anesthesia at normoventilation, 50% of brain tumor patients showed signs suggesting cerebral hypoperfusion, but this could not be demonstrated during isoflurane/nitrous oxide anesthesia. During PacO2 manipulations, consecutive measurements of the cerebral blood flow velocity may be inadequate to assess cerebral oxygenation.

The regulation of total creatine content in a myoblast cell line.

Total cellular creatine content is an important bioenergetic parameter in skeletal muscle. To understand its regulation we investigated creatine transport and accumulation in the G8 cultured skeletal myoblast line. Like other cell types, these contain a creatine transporter, whose activity, measured using a radiolabelling technique, was saturable (Km = 110 +/- 25 microM) and largely dependent on extracellular [Na+]. To study sustained influences on steady state creatine concentration we measured total cellular creatine content using a fluorimetric method in 48 h incubations. We found that the total cellular creatine content was relatively independent of extracellular creatine concentration, consistent with high affinity sodium-dependent uptake balanced by slow passive efflux. Accordingly, in creatine-free incubations net creatine efflux was slow (5 +/- 1% of basal creatine content per day over 6 days), while creatine content in 48 h incubations was reduced by 28 +/- 13% of control by the Na+, K(+)-ATPase inhibitor ouabain. Creatine accumulation after 48 h was stimulated by treatment with the mixed alpha- and beta-adrenergic agonist noradrenaline, the beta-adrenergic agonist isoproterenol, the beta 2-agonist clenbuterol and the cAMP analogue N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate, but was unaffected by the alpha 1 adrenergic agonist methoxamine. The noradrenaline enhancement of creatine accumulation at 48 h was inhibited by the mixed alpha- and beta-antagonist labetalol and by the beta-antagonist propranolol, but was unaffected by the alpha 2 antagonist phentolamine; greater inhibition was caused by the beta 2 antagonist butoxamine than the beta 1 antagonist atenolol. Creatine accumulation at 48 h was increased to 230 +/- 6% of control by insulin and by 140 +/- 13% by IGF-I (both at 3 nM). Creatine accumulation at 48 h was also increased to 280 +/- 40% of control by 3,3',5-triiodothyronine (at 70 microM) and to 220 +/- 35% of control by amylin (60 nM). As 3,3', 5-triiodothyronine, amylin and isoproterenol all stimulate the Na+, K(+)-ATPase, we suggest that they stimulate Na(+)-creatine cotransport indirectly by increasing the transmembrane [Na+] concentration gradient and membrane potential.

Assessment of mitochondrial function and control in normal and diseased states.

Mitochondrial function in muscle in vivo can be quantitatively evaluated using 31-phosphorus nuclear magnetic resonance. In resting muscle, the concentrations of ions (e.g. H+, Na+) and two of the major bioenergetic components (inorganic phosphate and creatine) are determined by regulated transcellular transport processes. During recovery after exercise the kinetics and control of mitochondrial ATP synthesis can be established. During exercise the relative contributions to ATP synthesis of phosphocreatine (using creatine kinase), anaerobic glycogenolysis and oxidative phosphorylation are dissected and have been shown to change with time. The consequences of mitochondrial lesions and dysfunctions on these processes have been summarised.

Laparoscopic fundoplication: a new technique with new complications?

We report pneumomediastinum, pneumopericardium, and subcutaneous emphysema occurring in patients who underwent laparoscopic fundoplication in our clinic. These complications might adversely affect hemodynamics during this procedure.

Haemodynamic effects of pneumoperitoneum for laparoscopic surgery: a comparison of CO2 with N2O insufflation.

We studied the haemodynamic effects of intra-abdominal insufflation with either CO2 (n = 15) or N2O (n = 15) in patients undergoing laparoscopic surgery. Haemodynamic variables were measured at increasing levels of intra-abdominal pressure up to 20 mmHg. In the CO2 group cardiac index decreased from 2.6 +/- 0.6 to 2.0 +/- 0.4 litre min-1 m-2 (mean +/- SD, P < 0.001) and in the N2O group from 2.6 +/- 0.5 to 1.8 +/- 0.4 litre min-1 m-2 (P < 0.001)). In the CO2 group, this was accompanied by increases in mean arterial pressure, systemic vascular resistance index and central venous pressure without change in heart rate. In contrast, during N2O insufflation mean arterial pressure decreased (from 77 +/- 8 to 63 +/- 15 mmHg (P < 0.001)) without change in vascular resistance. No further changes in haemodynamic variables were observed during head-up tilt in both groups. After desufflation mean arterial pressure increased in the N2O group to pre-insufflation levels and cardiac index increased in both groups (P < 0.001), but reached pre-insufflation levels only in the CO2 group. In both groups central venous O2 tension and saturation decreased at maximum intra-abdominal pressure and increased after release of the pneumoperitoneum. The results indicate that laparoscopic insufflation with either CO2 or N2O results in cardiovascular depression. Insufflation with N2O may decrease blood pressure, whereas mean arterial pressure is better preserved with CO2 insufflation.

Intraperitoneal local anaesthetics after laparoscopic cholecystectomy: effects on postoperative pain, metabolic responses and lung function.

We have compared the efficacy of 0.9% NaCl 20 ml (n = 15), 0.25% bupivacaine 20 ml (n = 15) and 0.5% lignocaine 20 ml (n = 15), administered i.p., in reducing postoperative pain and opioid requirements, and modifying the metabolic response to surgery and postoperative lung function after laparoscopic cholecystectomy. There were no differences in postoperative pain scores (visual analogue scale and verbal rating scale) between the three groups in the first 4 h after operation and in analgesic requirements during the first 24 h. In all groups, forced vital capacity, peak expiratory flow and forced expiratory volume in 1 s decreased 2 h after surgery (P < 0.001). Ventilatory values recovered only partially in the first 2 days after operation (P < 0.05), with no significant differences between groups. Plasma concentrations of glucose and cortisol increased after surgery (P < 0.05). Cortisol concentrations returned to baseline 48 h after operation. There were no significant differences between the groups in any measured variable. These data suggest that the administration of 20 ml of local anaesthetics i.p. is not effective in reducing postoperative pain, improving lung function, or attenuating the metabolic endocrine response after laparoscopic cholecystectomy.

A comparison of the effects of propofol and nitrous oxide on the electroencephalogram in epileptic patients during conscious sedation for dental procedures.

The influence of sedative doses of propofol or nitrous oxide on the electroencephalogram was studied in 11 mentally handicapped patients with treated epilepsy undergoing dental procedures. At one session, propofol was titrated to achieve conscious sedation. The mean (+/- SD) dose requirements were 5.5 +/- 1.1 mg.kg-1.h-1. In six patients, the electroencephalogram was unchanged during propofol administration. In three patients, there was a decrease in epileptic activity, and in two patients, paroxysmal discharges disappeared. At another session, nitrous oxide was administered by nasal mask. The mean (+/- SD) concentration of nitrous oxide needed was 43.6% +/- 4.8%. The electroencephalogram did not change in nine patients, whereas in two patients epileptic activity decreased. There were no clinical epileptoid or other adverse manifestations during any treatment or up to 48 h thereafter. The results of the present study suggest that propofol or nitrous oxide can be administered in subanesthetic doses for conscious sedation in mentally handicapped patients with treated epilepsy.

Pulmonary function and stress response after laparoscopic cholecystectomy: comparison with subcostal incision and influence of thoracic epidural analgesia.

Laparoscopic cholecystectomy (LPC) is increasingly used to treat symptomatic cholelithiasis. We compared the effects of cholecystectomy by subcostal incision to those of LPC on lung function and endocrine metabolic response. The effects of thoracic epidural analgesia for LPC were studied as well. Thirty patients undergoing elective cholecystectomy under general anesthesia were allocated to three study groups: group I, cholecystectomy by subcostal incision; group II, LPC; group III, LPC and epidural analgesia with 0.5% bupivacaine with epinephrine, followed by continuous epidural infusion of 6 mL of 0.5% bupivacaine. Forced vital capacity (FVC), peak expiratory flow, and forced expiratory volume in 1 s were measured with the patients in a half-sitting position. In all groups, sustained decreases in FVC, forced expiratory volume in 1 s, and peak expiratory flow were observed up to 24 h after surgery. Reduction of FVC was significantly more in group I compared with groups II and III (P less than 0.05). The FVC in group I decreased from 3.8 +/- 0.42 (SD) to 1.1 +/- 0.27 L (P less than 0.01), in group II from 3.6 +/- 1.46 to 2.1 +/- 0.94 L (P less than 0.05), and in group III from 3.8 +/- 0.92 to 2.8 +/- 0.90 L (P less than 0.05). In all groups, plasma glucose and cortisol increased after surgery compared with baseline levels (P less than 0.05). At 240 min after surgery, a small but significant decrease of cortisol was measured in group III (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of epidural and spinal anesthesia on blood rheology.

This study was designed to compare the influence of epidural and spinal anesthesia on blood viscosity. We studied 22 patients, ASA classification I, who underwent elective knee or ankle arthroscopy and received epidural (n = 11) or spinal (n = 11) anesthesia with plain bupivacaine, and 10 control volunteers, who did not undergo surgery or receive anesthesia. There were significant decreases in hematocrit, plasma viscosity, and whole-blood viscosity at high (70 s-1), medium (0.5 s-1), and low (0.05 s-1) shear rates. The magnitude of changes was similar in all groups but occurred earlier in the control group (between 10 and 30 min) and after spinal administration (between 10 and 30 min) rather than after epidural administration (between 30 and 60 min) of bupivacaine. Only spinal anesthesia was associated with a decrease in erythrocyte deformability. The observed rheologic changes are attributed to hemodilution from the intravenous administration of fluids and the redistribution of fluid in the intravascular and extravascular compartments after sympathetic blockade and to postural changes rather than the effect of bupivacaine on blood elements.

Characterization of peptide fluxes into human erythrocytes. A proton-n.m.r. study.

A new protocol for measuring cellular uptake of dipeptides was developed in which the problem of peptide hydrolysis is obviated by introduction into the cell suspension of a membrane-permeant peptidase inhibitor. The uptake of unlabelled dipeptide is readily monitored so long as some analytical technique is available for measuring the intracellular peptide concentration; in this study we used n.m.r. spectroscopy. Using this protocol, we demonstrated that dipeptide uptake by human erythrocytes occurs by simple diffusion through the lipid bilayer and not via a high-capacity protein-mediated transport system. Substantiating evidence includes demonstration that: (a) the fluxes are slow compared with known protein-mediated transport processes in human erythrocytes; (b) the uptake is not stereospecific; (c) the uptake does not display saturation kinetics; (d) the fluxes are significantly enhanced by butanol; (e) a distinct correlation exists between the size-corrected permeability coefficients of the dipeptides and their calculated n-octanol/water partition coefficients. It is calculated that under normal physiological conditions the diffusive fluxes of circulating plasma peptides into human erythrocytes are too small for these cells to play a significant role in dipeptide catabolism.

The effects of bupivacaine and pipecoloxylidide on platelet function in vitro.

The influence of bupivacaine and its major metabolite, pipecoloxylidide, on human platelet function was studied in vitro. Significant inhibition of ADP and collagen-induced platelet aggregation occurred only with concentrations of bupivacaine above 10 micrograms.ml-1. This concentration (10-25 micrograms.ml-1) is much higher than would be expected in routine clinical use of bupivacaine for epidural analgesia. The inhibition of platelet aggregation was associated with a significant decrease in beta-thromboglobulin secretion. In contrast, pipecoloxylidide had no effect on platelet aggregation or the beta-thromboglobulin release. We conclude that the previously reported 30-min time-lag between the maximal plasma concentration of bupivacaine and the inhibition of platelet aggregation is unlikely to be due to a metabolism of bupivacaine to pipecoloxylidide.

The influence of epidural analgesia on platelet function and correlation with plasma bupivacaine concentrations.

The effect of epidural anaesthesia with bupivacaine 0.5% on platelet aggregation was studied in seven patients undergoing transurethral resection of the prostate. Peak plasma concentrations of bupivacaine 470 +/- 270 ng ml-1 occurred at 30 min after administration. At that time there were no significant changes in platelet aggregation. However, the maximum rate of the primary- and secondary-aggregation velocities induced by 1.0 microM ADP were significantly decreased at 1 h and 3 h after bupivacaine administration. The maximum percentage ADP-induced platelet aggregation was also decreased significantly at 1 h and 3 h. The minimum concentration of ADP required to induce secondary-phase platelet aggregation was significantly increased at 1 h but not at 3 h. There was a significant correlation between bupivacaine concentrations and all platelet aggregation parameters except the maximum ADP-induced aggregation. Platelet inhibition occurred at plasma bupivacaine concentrations that were considerably lower than those needed to produce similar inhibition in vitro.