Does moderate intensity impact exercise and non-impact exercise induce acute changes in collagen biochemical markers related to osteoarthritis? - An exploratory randomized cross-over trial.

OBJECTIVE: To investigate acute changes in biochemical markers of cartilage turnover in response to moderate intensity exercise with and without joint impact in humans with knee osteoarthritis. DESIGN: We conducted a randomized, cross-over, exploratory clinical study. Twenty subjects with knee osteoarthritis (OA) were randomized, of which twenty completed 30 min of cycling and 15 completed 30 min of running on days 1 week apart. Fasting blood samples were taken before, immediately after and 1, 2, 3, and 24 h after activity was initiated. Midstream spot urine was sampled before and after activity. Serum samples were analyzed for concentrations of fragment of type II collagen degradation, C2M, fragment of type VI collagen degradation, C6M, cartilage oligomeric matrix protein, COMP, marker of type II collagen formation, PRO-C2, and urine for marker of crosslinked type II collagen degradation, CTX-II. To establish a reference, all subjects had similar samples taken during rest on a separate day. Data was analyzed in a restricted maximum likelihood based random effects linear mixed model. RESULTS: C2M trended to increase after cycling compared running (13.49%, 95%CI: -0.36-27.34%) and resting (12.88%, 95%CI: 0.2-25.6%) and the type II collagen formation/degradation ratio switched towards degradation after cycling, but not running. C6M trended to decrease after cycling (-8.1%, 95%CI: -14.8 to -1.4%) and running (-6.8%, 95%CI: -14.16-0.55%). CONCLUSION: In persons with knee OA moderate intensity exercise without joint impact may induce acute changes in circulating levels of biochemical markers reflecting type II and VI collagen degradation.

Administration of platelets to ruptured abdominal aortic aneurysm patients before open surgery: a prospective, single-blinded, randomised study.

BACKGROUND: In patients undergoing open surgery for a ruptured abdominal aortic aneurysm (rAAA), survivors demonstrate a high platelet count, and proactive administration of platelets (and fresh frozen plasma) appears to influence mortality. OBJECTIVES: This trial investigated the effect of platelets administered before transport to surgery. METHODS: In a prospective study design, patients were randomised to receive platelets (intervention; n = 61) or no platelets (control; n = 61) before transport to vascular surgery from 11 local hospitals. The study was terminated when one of the vascular surgical centres implemented endovascular repair for rAAA patients. RESULTS: Thirty days after surgery, mortality was 36% for patients with intervention vs 31% for controls (P = 0·32). Post-operative thrombotic events (14 vs 15; P = 0·69), renal failure (11 vs 10; P = 0·15) and pulmonary insufficiency (34 vs 39; P = 0·15) were similar in the two groups of patients. No adverse reactions to platelet administration were observed. In addition, length of stay in the intensive care unit was unaffected by intervention. CONCLUSIONS: For patients planned for open repair of a rAAA, we observed no significant effect of early administration of platelets with regard to post-operative complications and stay in the ICU or in hospital and also no significant effect on mortality.

Cerebral oximetry during preoperative resuscitation in elderly patients with hip fracture: a prospective observational study.

This study explores the association between postadmission and intraoperative cerebral oxygenation (ScO2), reflecting systemic perfusion, and postoperative mortality and delirium. Forty elderly (age > 65 years) patients with hip fractures were included in this prospective observational study. The ScO2 was determined using near-infrared spectroscopy at initial resuscitation after patients were admitted to the hospital and during surgery. Postoperative delirium was assessed up to seven days after surgery using the memorial delirium assessment scale and the confusion assessment method. Ten patients (25%) developed postoperative delirium within the first seven postoperative days. At initial resuscitation ScO2 was lower in patients that later developed delirium, but the difference was not significant (p = 0.331). Intraoperative ScO2 values remained similar in the two groups. Mortality regardless of cause was 10% (4 out of 40 patients) after 30 days. At initial resuscitation ScO2 was significant lower in the mortality group than in the surviving group (p = 0.042), and the ScO2 nadir values were also significant lower (p = 0.047). Low ScO2 during initial resuscitation (defined as ScO2 < 55 for a minimum of two consecutive minutes) was also significantly associated with 30-day mortality (p = 0.015). There were no associations between low blood pressure and postoperative delirium or 30-day mortality. We found that low preoperative ScO2 was better associated with 30-day all-cause mortality in elderly patients undergoing surgery for hip fracture than blood pressure measurements. Future studies in preoperative resuscitation of hip fracture patients should focus on perfusion measures as opposed to conventional haemodynamic.

Low vs. high haemoglobin trigger for transfusion in vascular surgery: protocol for a randomised trial.

BACKGROUND: In patients with cardiovascular disease, guidelines for administration of red blood cells (RBC) are mainly based on studies outside the vascular surgical setting with the recommendation to use a haemoglobin (hb) trigger-level lower than by guidelines from The European Society for Vascular Surgery. Restricting RBC transfusion may affect blood O2 transport with a risk for development of tissue ischaemia and postoperative complications. METHODS: In a single-centre, open-label, assessor blinded trial, 58 vascular surgical patients (> 40 years of age) awaiting open surgery of the infrarenal aorta or infrainguinal arterial bypass surgery undergo a web-based randomisation to one of two groups: perioperative RBC transfusion triggered by hb < 8 g/dl or hb < 9.7 g/dl. Administration of fluid follows an individualised strategy by optimising cardiac stroke volume and near-infrared spectroscopy determines tissue oxygenation. Serious adverse event rates are: myocardial injury (troponin-I ≥ 45 ng/l or ischaemic electrocardiographic findings at day 30), acute kidney injury, death, stroke and severe transfusion reactions. A follow-up visit takes place 30 days after surgery and a follow-up of serious adverse events in the Danish National Patient Register within 90 days is pending. DISCUSSION: This trial is expected to determine whether a RBC transfusion triggered by hb < 9.7 g/dl compared with hb < 8 g/dl results in adequate separation of postoperative hb levels, transfusion of more RBC units and maintains a higher tissue oxygenation. The results will inform the design of a multicentre trial for evaluation of important postoperative outcomes.

Near-infrared spectroscopy assessed cerebral oxygenation during open abdominal aortic aneurysm repair: relation to end-tidal CO2 tension.

During open abdominal aortic aneurism (AAA) repair cerebral blood flow is challenged. Clamping of the aorta may lead to unintended hyperventilation as metabolism is reduced by perfusion of a smaller part of the body and reperfusion of the aorta releases vasodilatory substances including CO2. We intend to adjust ventilation according end-tidal CO2 tension (EtCO2) and here evaluated to what extent that strategy maintains frontal lobe oxygenation (ScO2) as determined by near infrared spectroscopy. For 44 patients [5 women, aged 70 (48-83) years] ScO2, mean arterial pressure (MAP), EtCO2, and ventilation were obtained retrospectively from the anesthetic charts. By clamping the aorta, ScO2 and EtCO2 were kept stable by reducing ventilation (median, -0.8 l min(-1); interquartile range, -1.1 to -0.4; P < 0.001). During reperfusion of the aorta a reduction in MAP by 8 mmHg (-15 to -1; P < 0.001) did not prevent an increase in ScO2 by 2 % (-1 to 4; P < 0.001) as EtCO2 increased 0.5 kPa (0.1-1.0; P < 0.001) despite an increase in ventilation by 1.8 l min(-1) (0.9-2.7; P < 0.001). Changes in ScO2 related to those in EtCO2 (r = 0.41; P = 0.0001) and cerebral deoxygenation (-15 %) was noted in three patients while cerebral hyperoxygenation (+15 %) manifests in one patient. Thus changes in ScO2 were kept within acceptable limits (±15 %) in 91 % of the patients. For the majority of the patients undergoing AAA repair ScO2 was kept within reasonable limits by reducing ventilation by approximately 1 l min(-1) upon clamping of the aorta and increasing ventilation by approximately 2 l min(-1) when the lower body is reperfused.

Release of erythropoietin and neuron-specific enolase after breath holding in competing free divers.

Free diving is associated with extreme hypoxia. This study evaluated the combined effect of maximal static breath holding and underwater swimming on plasma biomarkers of tissue hypoxemia: erythropoietin, neuron-specific enolase and S100B, C-reactive protein, pro-atrial natriuretic peptide, and troponin T. Venous blood samples were obtained from 17 competing free divers before and 3 h after sessions of static apnea and underwater swimming. The heart was evaluated by echocardiography. Static apnea for 293 ± 78 s (mean ± SD) and subsequent 88 ± 21 m underwater swimming increased plasma erythropoietin from 10.6 ± 3.4 to 12.4 ± 4.1 mIU/L (P = 0.013) and neuron-specific enolase from 14.5 ± 5.3 to 24.6 ± 6.4 ng/mL (P = 0.017); C-reactive protein decreased from 0.84 ± 1.0 to 0.71 ± 0.67 mmol/L (P = 0.013). In contrast, plasma concentrations of S100B (P = 0.394), pro-atrial natriuretic peptide (P = 0.549), and troponin T (P = 0.125) remained unchanged and, as assessed by echocardiography, the heart was not affected. In competitive free divers, bouts of static and dynamic apnea increase plasma erythropoietin and neuron-specific enolase, suggesting that renal and neural tissue, rather than the heart, is affected by the hypoxia developed during apnea and underwater swimming.

External carotid artery flow maintains near infrared spectroscopy-determined frontal lobe oxygenation during ephedrine administration.

BACKGROUND: Phenylephrine and ephedrine affect frontal lobe oxygenation ([Formula: see text]) differently when assessed by spatially resolved near infrared spectroscopy. We evaluated the effect of phenylephrine and ephedrine on extra- vs intra-cerebral blood flow and on [Formula: see text]. METHODS: In 10 healthy males (age 20-54 yr), phenylephrine or ephedrine was infused for an ∼20 mm Hg increase in mean arterial pressure. Cerebral oxygenation (SavO2) was calculated from the arterial and jugular bulb oxygen saturations. Blood flow in the internal carotid artery (ICAf) and blood flow in the external carotid artery (ECAf) were assessed by duplex ultrasonography. Invos-5100c (SinvosO2) and Foresight (SforeO2) determined [Formula: see text] while forehead skin oxygenation (SskinO2) was assessed. RESULTS: Phenylephrine reduced SforeO2 by 6.9% (95% confidence interval: 4.8-9.0%; P<0.0001), SinvosO2 by 10.5 (8.2-12.9%; P<0.0001), and ECAf (6-28%; P=0.0001), but increased ICAf (5-21%; P=0.003) albeit with no consequence for SskinO2 or SavO2. In contrast, SforeO2 was maintained with administration of ephedrine while SinvosO2 and SavO2 decreased [by 3.1 (0.7-4.5%; P=0.017) and 2.1 (0.5-3.3%; P=0.012)] as arterial carbon dioxide pressure decreased (P=0.003). ICAf was stable and ECAf increased by 11 (4-18%; P=0.005) with administration of ephedrine while SskinO2 did not change. CONCLUSIONS: The effect of phenylephrine on ScO2 is governed by a decrease in external carotid blood flow since it increases cerebral blood flow as determined by flow in the internal carotid artery. In contrast, ScO2 is largely maintained with administration of ephedrine because blood flow to extracerebral tissue increases.

Ultrasound-guided locoregional anaesthesia for carotid endarterectomy: a prospective observational study.

INTRODUCTION: Ultrasound guidance is increasingly used for invasive anaesthetic procedures to improve efficacy, facilitate performance and reduce risk of complications. Herein, we present a simple approach to ultrasound-guided locoregional anaesthesia for patients undergoing eversion carotid endarterectomy. METHODS: At the level of the base of the carotid bifurcation, the needle was inserted at the lateral border of the sternocleidomastoid muscle and, guided by ultrasound, advanced 0.5-1 cm posterolateral to the carotid artery, where ropivacaine (7.5 mg ml(-1)) was injected. During retraction of the needle, additional local anaesthetic was administered beneath the sternocleidomastoid muscle and, finally, subcutaneous infiltration along the surgical incision line was performed. The primary study end point was the amount of additional ropivacaine (7.5 mg ml(-1)) provided intra-operatively. Secondary measures included the occurrence of puncture-related complications and the adverse effects to locoregional anaesthesia. RESULTS: Sixty consecutive patients admitted for primary carotid endarterectomy were prospectively included. The volume of administered ropivacaine for locoregional anaesthesia and subsequent intra-operative supplementation was 31.7 ± 3.5 and 1.9 ± 2.5 ml, respectively. There were no conversions to general anaesthesia. Intravascular or subarachnoid injection of local anaesthetic did not occur, and symptoms of local anaesthetic systemic toxicity did not present. Related to the blockade, hoarseness (72%), Horner syndrome (37%), cough (20%), facial palsy (13%) and dysphagia (12%) were observed and resolved on the first postoperative day. CONCLUSIONS: This observational study demonstrates that the described ultrasound-guided locoregional anaesthesia is suitable for eversion carotid endarterectomy and the amount of supplemental anaesthetic during the surgery is low.

Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise.

Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate (glucose+1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 M; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23±2 years; mean±S.D.). During the Sal trial, pH decreased from 7.41±0.01 at rest to 7.02±0.02 but only to 7.36±0.02 (P <0.05) during the Bicarb trial. Arterial lactate increased to 21.4±0.8 and 32.7±2.3 mM during the Sal and Bicarb trials, respectively (P <0.05). Also, the arterial-jugular venous lactate difference increased from-0.03±0.01 mM at rest to 3.2±0.9 mM (P <0.05) and 3.4±1.4 mM (P <0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8±0.6 at rest to 1.7±0.1 and 1.8±0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.

Anaerobic digestion of macroalgae: methane potentials, pre-treatment, inhibition and co-digestion.

In the present study we tested four macroalgae species--harvested in Denmark--for their suitability of bioconversion to methane. In batch experiments (53 degrees C) methane yields varied from 132 ml g volatile solids(-1) (VS) for Gracillaria vermiculophylla, 152 mi gVS(-1) for Ulva lactuca, 166 ml g VS(-1) for Chaetomorpha linum and 340 ml g VS(-1) for Saccharina latissima following 34 days of incubation. With an organic content of 21.1% (1.5-2.8 times higher than the other algae) S. latissima seems very suitable for anaerobic digestion. However, the methane yields of U. lactuca, G. vermiculophylla and C. linum could be increased with 68%, 11% and 17%, respectively, by pretreatment with maceration. U. lactuca is often observed during 'green tides' in Europe and has a high cultivation potential at Nordic conditions. Therefore, U. lactuca was selected for further investigation and co-digested with cattle manure in a lab-scale continuously stirred tank reactor. A 48% increase in methane production rate of the reactor was observed when the concentration of U. lactuca in the feedstock was 40% (VS basis). Increasing the concentration to 50% had no further effect on the methane production, which limits the application of this algae at Danish centralized biogas plant.

Lateral ridge augmentation in the posterior part of the mandible with an autogenous bone block graft harvested from the ascending mandibular ramus. A 10-year retrospective study.

PURPOSE: The objective of the present retrospective study was to assess the long-term implant treatment outcome and patient satisfaction after lateral ridge augmentation in the posterior mandible with autogenous bone block graft harvested from the ascending mandibular ramus. MATERIALS AND METHODS: Seventy-four lateral ridge augmentation procedures in the posterior mandible with an autogenous bone block graft harvested from the ascending mandibular ramus and delayed placement of 87 implants was conducted in 46 consecutive patients from 2002-2006. Records and radiographs were retrospectively analyzed. Twenty-four patients responded to a 10-years follow-up examination including 39 lateral ridge augmentation procedures and 48 implants. Survival of suprastructures and implants, peri-implant marginal bone loss, patient perception and professional evaluation of the final implant treatment was assessed after 10 years. RESULTS: The 10-year survival of suprastructures and implants was 100% as all the implants and suprastructures were present with limited peri-implant marginal bone loss. The patients were highly satisfied with the esthetic and implant treatment outcome. CONCLUSION: Lateral ridge augmentation in the posterior mandible with autogenous bone block graft from the ascending mandibular ramus is characterized by high long-term implant survival rate and patient satisfaction.

Sandwich osteotomy of the atrophic posterior mandible with interpositional autogenous bone block graft compared with bone substitute material: a systematic review and meta-analysis.

The objective of the present systematic review was to test the hypothesis that there were no differences in outcome of implant treatment after sandwich osteotomy in the atrophic posterior mandible with interpositional autogenous bone block graft, compared with bone substitute material. A MEDLINE/PubMed, Embase and Cochrane Library search in combination with hand-search of selected journals was conducted. Two short-term randomised controlled trials with a split-mouth study design and low risk of bias fulfilled the inclusion criteria. High survival rate of suprastructures and implants was disclosed with no significant difference between interpositional autogenous bone block graft compared with bone substitute material. Meta-analysis revealed patient-based implant survival risk ratio of 1.05 (95% CI: 0.88 to 1.25) and peri-implant marginal bone loss of 0.31mm (95% CI: -0.29 to 0.90) indicating no significant differences between the two treatments. High implant stability values, gain in vertical alveolar ridge height, bone formation, and few complications were reported with both treatments. Sandwich osteotomy with interpositional grafting material appears to be a predictable surgical technique for enhancement of the vertical alveolar ridge height in the atrophic posterior mandible prior to implant placement.

Cerebral oxygenation and metabolism during exercise following three months of endurance training in healthy overweight males.

Endurance training improves muscular and cardiovascular fitness, but the effect on cerebral oxygenation and metabolism remains unknown. We hypothesized that 3 mo of endurance training would reduce cerebral carbohydrate uptake with maintained cerebral oxygenation during submaximal exercise. Healthy overweight males were included in a randomized, controlled study (training: n = 10; control: n = 7). Arterial and internal jugular venous catheterization was used to determine concentration differences for oxygen, glucose, and lactate across the brain and the oxygen-carbohydrate index [molar uptake of oxygen/(glucose + (1/2) lactate); OCI], changes in mitochondrial oxygen tension (DeltaP(Mito)O(2)) and the cerebral metabolic rate of oxygen (CMRO(2)) were calculated. For all subjects, resting OCI was higher at the 3-mo follow-up (6.3 +/- 1.3 compared with 4.7 +/- 0.9 at baseline, mean +/- SD; P < 0.05) and coincided with a lower plasma epinephrine concentration (P < 0.05). Cerebral adaptations to endurance training manifested when exercising at 70% of maximal oxygen uptake (approximately 211 W). Before training, both OCI (3.9 +/- 0.9) and DeltaP(Mito)O(2) (-22 mmHg) decreased (P < 0.05), whereas CMRO(2) increased by 79 +/- 53 micromol x 100 x g(-1) min(-1) (P < 0.05). At the 3-mo follow-up, OCI (4.9 +/- 1.0) and DeltaP(Mito)O(2) (-7 +/- 13 mmHg) did not decrease significantly from rest and when compared with values before training (P < 0.05), CMRO(2) did not increase. This study demonstrates that endurance training attenuates the cerebral metabolic response to submaximal exercise, as reflected in a lower carbohydrate uptake and maintained cerebral oxygenation.

Initial administration of hydroxyethyl starch vs lactated Ringer after liver trauma in the pig.

BACKGROUND: This study tested the circulatory effectiveness of post-trauma administration of a large intravascular volume expander, hydroxyethyl starch 130/0.4 (HES), vs standard lactated Ringer's solution (RL). METHODS: Liver injury was inflicted in 14 pigs [31 (4) kg; mean (sd)] and treatment simulated an acute pre-hospital event: after a standard first-respond delay (7 min), volume administration was provided in three phases to simulate increasing intravascular access. In the first two phases, the fluid was administered either by HES or by RL and, during the last phase, all animals received HES to stabilize the intravascular volume. RESULTS: The liver trauma severed an equal number of 1-3 mm diameter blood vessels [1.4 (0.6)] and after 7 min, the blood loss was 184 (127) ml and mean arterial pressure had decreased by 19 (13) mm Hg (P<0.01). The intravascular volume expansion effect was 115 (25)% for HES and 76 (21)% for RL (P<0.05), yet oxygen uptake was maintained in zero of seven vs three of seven pigs and the survival was three of seven vs seven of seven, respectively (P<0.05). In these animals, the initial administration of HES provoked uncontrolled bleeding, whereas the administration of RL was associated with attenuated bleeding: total blood loss 2455 (1919) vs 311 (208) ml, respectively (P<0.01), reflecting that bleeding ceased in six of the pigs administered RL. CONCLUSIONS: After injury, the intravascular volume expanding effect of HES was larger than that for RL. However, initial administration of HES provoked uncontrolled haemorrhage, suggesting that prioritizing intravascular volume expansion did not result in stabilization of the circulation after haemorrhage.

Short implants (≤8mm) compared to standard length implants (>8mm) in conjunction with maxillary sinus floor augmentation: a systematic review and meta-analysis.

The objective was to test the hypothesis of no difference in the treatment outcome after the installation of short implants (≤8mm) in the posterior part of the maxilla compared to standard length implants (>8mm) in conjunction with maxillary sinus floor augmentation (MSFA) using the lateral window technique, after an observation period of ≥3years. A search of the MEDLINE, Embase, and Cochrane Library databases, in combination with a hand-search of relevant journals, was conducted. The search yielded 1102 titles. Finally, three studies that fulfilled the inclusion criteria were included. All were considered to have a low risk of bias. Meta-analyses revealed no significant differences in implant survival or peri-implant marginal bone loss between the two treatment modalities. However, the use of standard length implants in conjunction with MSFA was characterized by a tendency towards more peri-implant marginal bone loss. There was no statistically significant difference between the two treatment modalities with regard to overall patient satisfaction. Short implants seem to be a suitable alternative to standard length implants in conjunction with MSFA. However, further randomized controlled trials with larger patient samples and an observation period of more than 3years are needed before one treatment modality might be considered superior to the other.

Codigestion of manure and industrial organic waste at centralized biogas plants: process imbalances and limitations.

The present study focuses on process imbalances in Danish centralized biogas plants treating manure in combination with industrial waste. Collection of process data from various full-scale plants along with a number of interviews showed that imbalances occur frequently. High concentrations of ammonia or long chain fatty acids is in most cases expected to be the cause of microbial inhibitions/imbalances while foaming in the prestorage tanks and digesters is the most important practical process problem at the plants. A correlation between increased residual biogas production (suboptimal process conditions) and high fractions of industrial waste in the feedstock was also observed. The process imbalances and suboptimal conditions are mainly allowed to occur due to 1) inadequate knowledge about the waste composition, 2) inadequate knowledge about the waste degradation characteristics, 3) inadequate process surveillance, especially with regard to volatile fatty acids, and 4) insufficient pre-storage capacity causing inexpedient mixing and hindering exact dosing of the different waste products.

Kinetics of propionate conversion in anaerobic continuously stirred tank reactors.

The kinetic parameters of anaerobic propionate degradation by biomass from 7 continuously stirred tank reactors differing in temperature, hydraulic retention time and substrate composition were investigated. In substrate-depletion experiments (batch) the maximum propionate degradation rate, Amax, and the half saturation constant, Km, were initially estimated by applying the integrated Michaelis-Menten equation. Amax was in the range from 22.8 to 29.1 micromol gVS(-1) h(-1) while Km was in the range from 0.46-0.95 mM. In general, Amax gave a good reflection of the reactor performances. Secondly, the accuracy of the applied method was evaluated by use of radiotracer methodology. Amax was found to be 14-15% lower in the substrate-depletion experiment than in the radioisotope experiment due to endogenous propionate production. By including the endogenous propionate production, a 42-49% lower Km was estimated. The results demonstrate that the rate of endogenous substrate (propionate) production should be taken into account when estimating kinetic parameters in biomass from manure-based anaerobic reactors.

Hepatic lactate uptake versus leg lactate output during exercise in humans.

The exponential rise in blood lactate with exercise intensity may be influenced by hepatic lactate uptake. We compared muscle-derived lactate to the hepatic elimination during 2 h prolonged cycling (62 +/- 4% of maximal O(2) uptake, (.)Vo(2max)) followed by incremental exercise in seven healthy men. Hepatic blood flow was assessed by indocyanine green dye elimination and leg blood flow by thermodilution. During prolonged exercise, the hepatic glucose output was lower than the leg glucose uptake (3.8 +/- 0.5 vs. 6.5 +/- 0.6 mmol/min; mean +/- SE) and at an arterial lactate of 2.0 +/- 0.2 mM, the leg lactate output of 3.0 +/- 1.8 mmol/min was about fourfold higher than the hepatic lactate uptake (0.7 +/- 0.3 mmol/min). During incremental exercise, the hepatic glucose output was about one-third of the leg glucose uptake (2.0 +/- 0.4 vs. 6.2 +/- 1.3 mmol/min) and the arterial lactate reached 6.0 +/- 1.1 mM because the leg lactate output of 8.9 +/- 2.7 mmol/min was markedly higher than the lactate taken up by the liver (1.1 +/- 0.6 mmol/min). Compared with prolonged exercise, the hepatic lactate uptake increased during incremental exercise, but the relative hepatic lactate uptake decreased to about one-tenth of the lactate released by the legs. This drop in relative hepatic lactate extraction may contribute to the increase in arterial lactate during intense exercise.

Effect of tryptone and ammonia on the biogas process in continuously stirred tank reactors treating cattle manure.

Two thermophilic continuously stirred tank reactors, R1 and R2, were subject to pulses of tryptone and ammonia. R1 was operated at an ammonia-N concentration of 3.0 g l(-1) and R2 was operated at an ammonia-N concentration of 1.7 g l(-1). Shock loads of tryptone (10 g l(-1), 10 g l(-1), 15 g l(-1)) had an immediate stimulating effect on methanogenesis for both reactors illustrated by significant peaks in methane production but also led to an organic overloading illustrated by a steep increase in volatile fatty acids (VFA) concentration. Three days after the pulses a second peak in acetate concentration and a decrease in methane production indicated an ammonia-inhibition of the acetoclastic methanogens. During the pulses of tryptone the performance of R1 was slightly more affected than R2. Pulses of ammonia (0.79 g l(-1) as N) resulted in a decrease in methane production of both reactors but no immediate increases in VFA concentrations was observed illustrating that the ammonia inhibition during this experiment was an overall inhibition of the biogas process and not only an inhibition of the methanogens.

Postoperative volume balance: does stroke volume increase in Trendelenburg's position?

In healthy humans, stroke volume (SV) and cardiac output (CO) do not increase with expansion of the central blood volume by head-down tilt or administration of fluid. Here, we exposed 85 patients to Trendelenburg's position about one hour after surgery while cardiovascular variables were determined non-invasively by Modelflow. In Trendelenburg's position, SV (83 ± 19 versus 89 ± 20 ml) and CO (6·2 ± 1·8 versus 6·8 ± 1·8 l/min; both P<0·05) increased, while heart rate (75 ± 15 versus 76 ± 14 b min-1 ) and mean arterial pressure were unaffected (84 ± 15 versus 84 ± 16 mmHg). For the 33 patients (39%) with a > 10% increase in SV (from 78 ± 16 to 90 ± 17 ml) corresponding to an increase in CO from 5·9 ± 1·5 to 6·9 ± 1·6 l min-1 (P<0·05) when tilted head-down, administration of 250 ml Ringer's lactate solution increased SV (to 88 ± 18 ml) and CO (to 6·8 ± 1·7 l min-1 ). In conclusion, determination of SV and/or CO in Trendelenburg's position can be used to evaluate whether a patient is in need of IV fluid as here exemplified after surgery.