Good quality of life before cardiac arrest predicts good quality of life after resuscitation.

BACKGROUND: The survival rate of cardiac arrest patients is increasing. Our aim was to compare the quality of life before and after cardiac arrest and analyse the factors associated with outcome. METHODS: All adult cardiac arrest patients admitted to the Tampere University Hospital intensive care unit between 2009 and 2011 were included in a retrospective follow-up study if surviving to discharge and were asked to return a questionnaire after 6 months. Data on patient demographics and pre-arrest quality of life were retrieved from medical records. Data are given as means (SD) or medians [Q1 , Q3 ]. We used logistic regression to identify factors associated with better quality of life after cardiac arrest. RESULTS: Six months after cardiac arrest, 36% (79/222) were alive and 70% (55/79) of those patients completed the follow-up EuroQoL (EQ-5D) quality of life questionnaire. Median values for the EQ-5D before and after cardiac arrest were 0.89 [0.63, 1] and 0.89 [0.62, 1], respectively (P = 0.75). Only the EQ-5D prior to cardiac arrest was associated with better quality of life afterwards (OR 1.2; 95% CI 1.0-1.3; P = 0.02). CONCLUSIONS: Quality of life remained good after cardiac arrest especially in those patients who had good quality of life before cardiac arrest.

Predictive value of urine interleukin-18 in the evolution and outcome of acute kidney injury in critically ill adult patients.

BACKGROUND: Interleukin-18 (IL-18) is a pro-inflammatory protein, which mediates ischaemic tubular injury, and has been suggested to be a sensitive and specific biomarker for acute kidney injury (AKI). The predictive value of IL-18 in the diagnosis, evolution, and outcome of AKI in critically ill patients is still unclear. METHODS: We measured urine IL-18 from critically ill patients at intensive care unit (ICU) admission and 24 h. We evaluated the association of IL-18 with developing new AKI, renal replacement therapy (RRT), and 90-day mortality. We calculated areas under receiver operating characteristics curves (AUCs), best cut-off values, and positive likelihood ratios (LR+) for IL-18 concerning these endpoints. Additionally, we compared the predictive value of IL-18 at ICU admission to that of urine neutrophil gelatinase-associated lipocalin (NGAL). RESULTS: In this study population of 1439 patients the highest urine IL-18 during the first 24 h in the ICU associated with the development of AKI with an AUC [95% confidence interval (CI)] of 0.586 (0.546-0.627) and with the development of Stage 3 AKI with an AUC (95% CI) of 0.667 (0.591-0.774). IL-18 predicted the initiation of RRT with an AUC (95% CI) of 0.655 (0.572-0.739), and 90-day mortality with an AUC (95% CI) of 0.536 (0.497-0.574). CONCLUSIONS: IL-18 had poor-to-moderate ability to predict AKI, RRT, or 90-day mortality in this large cohort of critically ill patients. Thus, it should be used with caution for diagnostic or predictive purposes in the critically ill.

Cardiac arrest teams and medical emergency teams in Finland: a nationwide cross-sectional postal survey.

BACKGROUND: The implementation, characteristics and utilisation of cardiac arrest teams (CATs) and medical emergency teams (METs) in Finland are unknown. We aimed to evaluate how guidelines on advanced in-hospital resuscitation have been translated to practice. METHODS: A cross-sectional postal survey including all public hospitals providing anaesthetic services. RESULTS: Of the 55 hospitals, 51 (93%) participated in the study. All hospitals with intensive care units (university and central hospitals, n = 24) took part. In total, 88% of these hospitals (21/24) and 30% (8/27) of the small hospitals had CATs. Most hospitals with CATs (24/29) recorded team activations. A structured debriefing after a resuscitation attempt was organised in only one hospital. The median incidence of in-hospital cardiac arrest in Finland was 1.48 (Q1 = 0.93, Q3 = 1.93) per 1000 hospital admissions. METs had been implemented in 31% (16/51) of the hospitals. A physician participated in MET activation automatically in half (8/16) of the teams. Operating theatres (13/16), emergency departments (10/16) and paediatric wards (7/16) were the most common sites excluded from the METs' operational areas. The activation thresholds for vital signs varied between hospitals. The lower upper activation threshold for respiratory rate was associated with a higher MET activation rate. The national median MET activation rate was 2.3 (1.5, 4.8) per 1000 hospital admissions and 1.5 (0.96, 4.0) per every cardiac arrest. CONCLUSIONS: Current guidelines emphasise the preventative actions on in-hospital cardiac arrest. Practices are changing accordingly but are still suboptimal especially in central and district hospitals. Unified guidelines on rapid response systems are required.

The quality of manual chest compressions during transport--effect of the mattress assessed by dual accelerometers.

BACKGROUND: The quality of cardiopulmonary resuscitation (CPR) has an impact on survival. The quality may be impaired if the patient needs to be transported to the hospital with ongoing CPR. The aim of this study was to analyse whether the quality of CPR can be improved during transportation by using real-time audiovisual feedback. In addition, we sought to evaluate the real compression depths taking into account the mattress and stretcher effect. METHODS: Paramedics (n = 24) performed standard CPR on a Resusci Anne Mannequin in a moving ambulance. Participants were instructed to perform CPR according to European Resuscitation Council Resuscitation guidelines 2010. Each pair acted as their own controls performing CPR first without and then with the feedback device. Compression depth, rate and no-flow fraction and also the mattress effect were recorded by using dual accelerometers by two Philips, HeartStart MRx Q-CPR defibrillators. RESULTS: In the feedback phase, the mean compression depth increased from 51 (10) to 56 (5) mm (P < 0.001), and the percentage of compression fractions with adequate depth was 60% vs. 89% (P < 0.001). However, taking account of the mattress effect, the real depth was only 41 (8) vs. 44 (5) mm without and with feedback, respectively (P < 0.001). The values for compression rate did not differ. CONCLUSIONS: CPR quality was good during transportation in general. However, the results suggest that the feedback system improves CPR quality. Dual accelerometer measurements show, on the other hand, that the mattress effect may be a clinically relevant impediment to high quality CPR.

Vital dysfunctions after intensive care discharge: prevalence and impact on patient outcome.

BACKGROUND: Patients discharged from the intensive care unit (ICU) are at increased risk for serious adverse events (SAEs). Recording vital functions and comprehending the consequences of altered vitals on general wards may be suboptimal. This potentially endangers recovery after successful intensive care. We aimed to determine the prevalence of vital dysfunctions after ICU discharge and their effect on patient outcome. METHODS: A prospective observational study. Adult patients discharged from a tertiary referral hospital ICU to general wards without treatment limitations were visited 24 h afterwards; their vitals were measured and reported to ward staff. Attending ward nurse responsible for patient was interviewed. RESULTS: The cohort consisted of 184 patients who had survived the first 24 h on the ward without complications (age: 57 ± 16 years; male: 68%). The prevalence of objectively measured vital dysfunctions was 15%, and the attending nurse had been unusually concerned about the patient in 19% of cases. Of the 184 patients, 9.8% subsequently suffered an SAE. In a multivariate logistic regression model, only vital dysfunctions (odds ratio 3.79; 95% confidence interval 1.18-12.2) and nurse concern (3.63; 1.17-11.3) were independently associated with an increased incidence of SAE. Medical emergency team (MET) assistance was never considered necessary by ward staff. Sensitivity of observed altered vitals on SAEs was 50% and specificity 89%. Sensitivity of nurse concern was 26%, specificity 84%. CONCLUSIONS: Simple vital function measurement and attending ward nurse's subjective assessment facilitate early detection of post-ICU patients at risk. The threshold in seeking assistance through MET remains high.

Evaluation of sublingual microcirculatory blood flow in the critically ill.

BACKGROUND: The microcirculation regulates the supply of oxygen and nutrients to tissues. The sublingual region is frequently used as a window to microcirculation in critically ill patients. Numerous studies have reported impaired sublingual microcirculatory flow. We hypothesized that the quality of sidestream dark field imaging (SDF) recordings could be systematically analyzed to justify the monitoring of sublingual microcirculation in interventional studies or in clinical practice. METHODS: The sublingual microcirculation in critically ill patients with septic shock, open heart surgery, or alcoholic pancreatitis, and healthy subjects was recorded with a hand held SDF device by one trained investigator in observational setting. A total of 82 video recording sessions were performed and 240 video clips eligible for quality assessment were identified. Quality assessment was performed offline by two investigators independently and blinded for the origin of the video file. RESULTS: Of the 240 clips, pressure artifact was detected in 86 (36%), major blood in 5 (2.1%), major saliva in 21 (8.8%) and extreme brightness causing loss of visible capillaries in 16 (6.7%) clips. The dominating vessel architecture was multiple size vessels in 228 (95%) and repeating capillary loop motif in 12 (5.0%). The mean (± SD) relative size reduction during stabilization was -6.9% (± 4.7%). Excellent technical quality was detected in 74 of 240 (30.8%) recordings. CONCLUSIONS: Our findings highlight the need of a comprehensive training period and reporting of data quality before findings with SDF imaging can be accepted as surrogate end points in interventional studies or as guidance in clinical practice.

Vascular adhesion protein-1 and syndecan-1 in septic shock.

BACKGROUND: Constituents of vascular endothelial surface layer (glycocalyx), e.g. an anchor protein syndecan-1 (SDC-1), can be detected in plasma in many inflammatory conditions. In inflammation, vascular adhesion protein-1 (VAP-1) is rapidly translocated to the apical side of the endothelial cells and may be released to plasma in a soluble form. We hypothesized that glycocalyx injury coincides with VAP-1 activation on endothelial cells. To test the hypothesis, we measured SDC-1 and VAP-1 levels in 20 patients with septic shock. METHODS: A prospective observational study was conducted in two multidisciplinary critical care units in two tertiary academic teaching hospitals with 20 mechanically ventilated adult patients with septic shock, on days 1 and 4 of treatment. Twenty healthy adults were enrolled as a control group. Plasma SDC-1 content, serum VAP-1 activity, platelets, and leukocyte count were measured in septic shock group at baseline and at 72 h and compared with those of healthy controls. RESULTS: VAP-1 activity and SDC-1 content were significantly increased in septic patients' group (P < 0.01) in comparison with controls. VAP-1 activity and SDC-1 content correlated positively to each other, and negatively to platelet count. In the septic shock group SDC-1 correlated on day 1 to SOFA score. CONCLUSIONS: We found increased VAP-1 activity and SDC-1 content in critically ill patients with septic shock. Based on our results, the role of VAP-1 in shock pathogenesis should be studied with semicarbazide-sensitive amine oxidase activity blocking agents and substrate affinity testing.

Corticosteroid therapy in intensive care unit patients with PCR-confirmed influenza A(H1N1) infection in Finland.

OBJECTIVE: To evaluate the incidence, treatment, and outcome of influenza A(H1N1) in Finnish intensive care units (ICUs) with special reference to corticosteroid treatment. METHODS: During the H1N1 outbreak in Finland between 11 October and 31 December 2009, we prospectively evaluated all consecutive ICU patients with high suspicion of or confirmed pandemic influenza A(H1N1) infection. We assessed severity of acute disease and daily organ dysfunction. Ventilatory support and other concomitant treatments were evaluated and recorded daily throughout the ICU stay. The primary outcome was hospital mortality. RESULTS: During the 3-month period altogether 132 ICU patients were tested polymerase chain reaction-positive for influenza A(H1N1). Of these patients, 78% needed non-invasive or invasive ventilatory support. The median (interquartile) length of ICU stay was 4 [2-12] days. Hospital mortality was 10 of 132 [8%, 95% confidence interval (CI) 3-12%]. Corticosteroids were administered to 72 (55%) patients, but rescue therapies except prone positioning were infrequently used. Simplified Acute Physiology Score II and Sequential Organ Failure Assessment scores in patients with and without corticosteroid treatment were 31 [24-36] and 6 [2-8] vs. 22 [5-30] and 3 [2-6], respectively. The crude hospital mortality was not different in patients with corticosteroid treatment compared to those without: 8 of 72 (11%, 95% CI 4-19%) vs. 2 of 60 (3%, 95% CI 0-8%) (P = 0.11). CONCLUSIONS: The majority of H1N1 patients in ICUs received ventilatory support. Corticosteroids were administered to more than half of the patients. Despite being more severely ill, patients given corticosteroids had comparable hospital outcome with patients not given corticosteroids.

Lactate concentrations in the rectal lumen in patients in early septic shock.

BACKGROUND: Previously, we observed that rectal luminal lactate was higher in non-survivors compared with survivors of severe sepsis or septic shock persisting >24 h. The present study was initiated to further investigate this tentative association between rectal luminal lactate and mortality in a larger population of patients in early septic shock. METHODS: A prospective observational multicentre study of 130 patients with septic shock at six general ICU's of university hospitals. Six to 24 h after the onset of septic shock, the concentration of lactate in the rectal lumen was estimated by a 4-h equilibrium dialysis. Dialysate concentrations of lactate were determined using an auto-analyser. RESULTS: The overall 30-day mortality was 32%, with age and Simplified acute physiology scores II and sequential organ failure assessment scores being significantly higher in non-survivors. In contrast, there were no differences in concentrations of lactate in the rectal lumen [2.2 (1.4-4.1) and 2.8 (1.6-5.1) mmol/l (P=0.34)] (medians and 25th-75th percentiles) or arterial blood [2.1 (1.4-4.2) and 2.0 (1.3-3.2) mmol/l (P=0.15)] between non-survivors and survivors. The rectal-arterial difference of the lactate concentration was higher in survivors. There were no differences in blood pressure, noradrenaline dose or central venous oxygen saturation between the groups. CONCLUSION: In this prospective, observational study of unselected patients with early septic shock, there was no difference in the concentration of lactate in the rectal lumen between non-survivors and survivors. TRIAL REGISTRATION: Clinicaltrials.gov (no: NCT00197938).

Prehospital therapeutic hypothermia for comatose survivors of cardiac arrest: a randomized controlled trial.

BACKGROUND: Intravenous infusion of ice-cold fluid is considered a feasible method to induce mild therapeutic hypothermia in cardiac arrest survivors. However, only one randomized controlled trial evaluating this treatment exists. Furthermore, the implementation rate of prehospital cooling is low. The aim of this study was to evaluate the efficacy and safety of this method in comparison with conventional therapy with spontaneous cooling often observed in prehospital patients. METHODS: A randomized controlled trial was conducted in a physician-staffed helicopter emergency medical service. After successful initial resuscitation, patients were randomized to receive either +4 degrees C Ringer's solution with a target temperature of 33 degrees C or conventional fluid therapy. As an endpoint, nasopharyngeal temperature was recorded at the time of hospital admission. RESULTS: Out of 44 screened patients, 19 were analysed in the treatment group and 18 in the control group. The two groups were comparable in terms of baseline characteristics. The core temperature was markedly lower in the hypothermia group at the time of hospital admission (34.1+/-0.9 degrees C vs. 35.2+/-0.8 degrees C, P<0.001) after a comparable duration of transportation. Otherwise, there were no significant differences between the groups regarding safety or secondary outcome measures such as neurological outcome and mortality. CONCLUSION: Spontaneous cooling alone is insufficient to induce therapeutic hypothermia before hospital admission. Infusion of ice-cold fluid after return of spontaneous circulation was found to be well tolerated and effective. This method of cooling should be considered as an important first link in the 'cold chain' of prehospital comatose cardiac arrest survivors.

Effects of levosimendan on indocyanine green plasma disappearance rate and the gastric mucosal-arterial pCO2 gradient in abdominal aortic aneurysm surgery.

BACKGROUND: Levosimendan has a dual mechanism of action: it improves myocardial contractility and causes vasodilatation without increasing myocardial oxygen demand. In a laboratory setting, it selectively increases gastric mucosal oxygenation in particular and splanchnic perfusion in general. The aim of our study was to describe the effects of levosimendan on systemic and splanchnic circulation during and after abdominal aortic surgery. METHODS: Twenty abdominal aortic aneurysm surgery patients were randomized to receive either levosimendan (n=10) or placebo (n=10) in a double-blinded manner. Both the mode of anaesthesia and the surgical procedures were performed according to the local guidelines. Automatic gas tonometry was used to measure the gastric mucosal partial pressure of carbon dioxide. Systemic indocyanine green clearance plasma disappearance rate (ICG-PDR) was used to estimate the total splanchnic blood flow. RESULTS: The immediate post-operative recovery was uneventful in the two groups with a comparable, overnight length of stay in the intensive care unit. Cumulative doses of additional vasoactive drugs were comparable between the groups, with a tendency towards a higher cumulative dose of noradrenaline in the levosimendan group. After aortic clamping, the cardiac index was higher [4(3.8-4.7) l/min/m(2) vs. 2.6(2.3-3.6) l/min/m(2); P<0.05] and the gastric mucosal-arterial pCO(2) gradient was lower in levosimendan-treated patients [0.9(0.6-1.2) kPa vs. 1.7(1.2-2.1) kPa; (P<0.05)]. However, the total splanchnic blood flow, estimated by ICG-PDR, was comparable [29(21-29)% vs. 20(19-25)%; NS]. Organ dysfunction scores (sequential organ dysfunction assessment) were similar between the groups on the fifth post-operative day. CONCLUSION: Levosimendan favours gastric perfusion but appears not to have a major effect on total splanchnic perfusion in patients undergoing an elective aortic aneurysm operation.

Regulation of transpirational water loss in Quercus suber trees in a Mediterranean-type ecosystem.

Sap flux density in branches, leaf transpiration, stomatal conductance and leaf water potentials were measured in 16-year-old Quercus suber L. trees growing in a plantation in southern Portugal to understand how evergreen Mediterranean trees regulate water loss during summer drought. Leaf specific hydraulic conductance and leaf gas exchange were monitored during the progressive summer drought to establish how changes along the hydraulic pathway influence shoot responses. As soil water became limiting, leaf water potential, stomatal conductance and leaf transpiration declined significantly. Predawn leaf water potential reflected soil water potential measured at 1-m depth in the rhizospheres of most trees. The lowest predawn leaf water potential recorded during this period was -1.8 MPa. Mean maximum stomatal conductance declined from 300 to 50 mmol m(-2) s(-1), reducing transpiration from 6 to 2 mmol m(-2) s(-1). Changes in leaf gas exchange were attributed to reduced soil water availability, increased resistances along the hydraulic pathway and, hence, reduced leaf water supply. There was a strong coupling between changes in soil water content and stomatal conductance as well as between stomatal conductance and leaf specific hydraulic conductance. Despite significant seasonal differences among trees in predawn leaf water potential, stomatal conductance, leaf transpiration and leaf specific hydraulic conductance, there were no differences in midday leaf water potentials. The strong regulation of changes in leaf water potential in Q. suber both diurnally and seasonally is achieved through stomatal closure, which is sensitive to changes in both liquid and vapor phase conductance. This sensitivity allows for optimization of carbon and water resource use without compromising the root-shoot hydraulic link.

The proportion of intensive care unit admissions related to alcohol use: a prospective cohort study.

BACKGROUND: Alcohol abuse is a risk factor for serious illnesses, and a history of chronic alcohol abuse adversely affects the outcome of critically ill patients. It is not known what proportion of intensive care unit (ICU) admissions is related to alcohol use. Therefore, we investigated the proportion of emergency admissions related to alcohol. METHODS: A prospective cohort study was conducted in a university hospital ICU. All adult patients (n = 893) who underwent emergency admission to our ICU during a period of 1 year were studied. RESULTS: The admitting physician determined whether there was a relationship between alcohol use and admission. ICU and hospital mortality and ICU length of stay (LOS) were recorded. The Therapeutic Intervention Scoring System (TISS) was used for ICU resource use estimation. There was a relationship between alcohol use and admission in 24% (215/893) of admissions and, in 156/893 admissions (17.5%), this seemed to be definite. ICU LOS was 1.2 days (0.7; 2.3) (median; interquartile range) for alcohol-related and 1.8 days (0.9; 3.6) for other admissions (P < 0.001). Patients with alcohol-related admissions consumed 17.8% of ICU patient-days and 18.7% of all accumulated TISS scores. ICU (8.8 vs. 10.5%, P = 0.603) and hospital (19.1 vs. 20.2%, P = 0.769) mortalities were no different between alcohol-related and other admissions. CONCLUSION: ICU admission is very often related to long-term chronic and/or occasional alcohol use.

Physiological and morphological responses to water stress in two Acacia species from contrasting habitats.

Container-grown seedlings of Acacia tortilis Forsk. Hayne and A. xanthophloea Benth. were watered either every other day (well watered) or every 7 days (water-stressed) for 1 year in a greenhouse. Total plant dry mass (T(dm)), carbon allocation and water relations were measured monthly. Differences in leaf area (LA) accounted for differences in T(dm) between the species, and between well-watered and water-stressed plants. Reduction in LA as a result of water stress was attributed to reduced leaf initiation, leaf growth rate and leaf size. When subjected to prolonged water stress, Acacia xanthophloea wilted more rapidly than A. tortilis and, unlike A. tortilis, lost both leaves and branches. These differences between species were attributed to differences in the allocation of carbon between leaves and roots and in the ability to adjust osmotically. Rapid recovery in A. xanthophloea following the prolonged water-stress treatment was attributed to high cell wall elasticity. Previous exposure to water stress contributed to water-stress resistance and improved recovery after stress.

Dobutamine compensates deleterious hemodynamic and metabolic effects of vasopressin in the splanchnic region in endotoxin shock.

BACKGROUND: Vasopressin is a potent vasopressor in septic shock, but it may impair splanchnic perfusion. We compared the effects of vasopressin alone and in combination with dobutamine on systemic and splanchnic circulation and metabolism in porcine endotoxin shock. METHODS: Twelve pigs were randomized to receive either vasopressin (VASO, n = 6) or vasopressin in combination with dobutamine (DOBU, n = 6) during endotoxin shock (E. coli endotoxin infusion). Endotoxin infusion rate was increased to induce hypotension after which vasoactive drugs were started. We aimed to keep systemic mean arterial pressure (MAP) >70 mmHg by vasopressin; the goal of dobutamine infusion was to prevent decrease in cardiac output often associated with vasopressin infusion. Regional blood flows, oxygen delivery and consumption, arterial and regional lactate concentrations were measured. RESULTS: Mean arterial pressure >70 mmHg was achieved in both the VASO and DOBU groups. After the primary decrease of cardiac output by vasopressin, systemic blood flow remained stable in vasopressin-treated animals. However, vasopressin as a monotherapy decreased portal venous blood flow. This was prevented by dobutamine. Vasopressin also induced splanchnic lactate release and arterial hyperlactatemia, which were not observed when dobutamine was combined with vasopressin. CONCLUSION: Dobutamine prevents adverse hemodynamic and metabolic effects of vasopressin in septic shock.

Dopexamine reverses colonic but not gastric mucosal perfusion defects in lethal endotoxin shock.

BACKGROUND: Whilst dopexamine appears to increase overall splanchnic blood flow in postoperative and septic patients, the effects on gastric mucosal perfusion are controversial and based on concomitantly increasing mucosal to arterial PCO(2) gradients (PdCO(2)). We hypothesized that dopexamine alters splanchnic blood flow distribution and metabolism during experimental endotoxin shock and modifies the inflammatory response induced by endotoxin. METHODS: In an experiment with anaesthetized normovolaemic, normoventilated pigs, 21 animals were randomized into: (i). subacute lethal endotoxin shock for 14 h (n=7 at baseline); (ii). endotoxin shock with dopexamine infusion (aiming to exceed baseline cardiac output, n=7); or (iii). controls (n=7). Regional blood flow and metabolism were monitored. RESULTS: Endotoxin produced a hypodynamic phase followed by a normo/hyperdynamic, hypotensive phase. Despite increasing systemic blood flow in response to dopexamine, proportional splanchnic blood flow decreased during the hypodynamic phase. Dopexamine gradually decreased fractional coeliac trunk flow, while fractional superior mesenteric arterial flow increased. Dopexamine induced early arterial hyperlactataemia and augmented the gastric PdCO(2) gradient while colonic luminal lactate release and colonic PdCO(2) gradient were reversed. Dopexamine did not modify the inflammatory response as evaluated by arterial IL-1beta and IL-6 concentrations. CONCLUSIONS: Dopexamine protects colonic, but not gastric mucosal epithelium in experimental endotoxin shock. This may be related to redistribution of blood flow within the splanchnic circulation.

Analysis of depth profiling data obtained by confocal Raman microspectroscopy.

The nominal depth resolution achieved in confocal Raman microscopy is on the order of a few micrometers. Often, however, the depth resolution is decreased by light refraction at the sample surface. The problem can be avoided with the use of an immersion objective and index matching oils. Through this intervention the instrument point-spread function (PSF) can be assumed to be independent of the depth of focus in the sample, and spatially invariant depth profiles can be acquired. In this work the instrument PSF was determined by measuring a depth profile of a thick uniform sample and calculating the first derivative of the depth profile curve. The first-derivative method was also used to determine sample thickness. Convolution with the PSF makes it possible to simulate the behavior of the instrument with different sample functions. It is also possible to use the instrument PSF to deconvolve depth-profiling data. Deconvolution reduces the blurring effect of the instrument and increases the depth resolution. Deconvolution can also be used in analysis of the sample surface position and in layer structure analysis. In this paper we show how the convolution integral can be used with the immersion sampling technique to determine the PSF and how the sample thickness can be determined.

Reperfusion but not acute ischemia in pig small intestine induces transcriptionally mediated heat shock response in situ.

BACKGROUND: Although there is data on the cytoprotective role of heat shock proteins in intestinal ischemia-reperfusion, the effects of ischemia and reperfusion per se on the small intestinal heat shock response have been poorly characterized. METHODS: Four female pigs were subjected to 60-min ischemia by superior mesenteric artery occlusion followed by 360-min reperfusion. Systemic and local hemodynamics were monitored. Samples from the jejunal mucosa and muscularis were obtained for histology and for time series molecular biologic analyses of heat shock transcription factor 1 (HSF1), hsp70 mRNA and Hsp70 protein. RESULTS: A 30-min reperfusion of jejunum after a preceding 1-hour ischemia results in a significantly increased DNA-binding activity of HSF1, in a 10-fold increase of hsp70 mRNA in the mucosal and in a 7-fold increase in the muscular layers. Translational activation and accumulation of Hsp70 protein occurs after 60 min of reperfusion in the intestine. Nevertheless, a 60-min ischemia inducing mucosal detachment does not induce the heat shock response at any level analyzed. CONCLUSIONS: Ischemia alone is insufficient to induce the heat shock response, whereas subsequent reperfusion induces the response via transcriptionally mediated induction of Hsp70 synthesis both in the mucosal and muscular layers.

Age-related effects on leaf area/sapwood area relationships, canopy transpiration and carbon gain of Norway spruce stands (Picea abies) in the Fichtelgebirge, Germany.

Stand age is an important structural determinant of canopy transpiration (E(c)) and carbon gain. Another more functional parameter of forest structure is the leaf area/sapwood area relationship, A(L)/A(S), which changes with site conditions and has been used to estimate leaf area index of forest canopies. The interpretation of age-related changes in A(L)/A(S) and the question of how A(L)/A(S) is related to forest functions are of current interest because they may help to explain forest canopy fluxes and growth. We conducted studies in mature stands of Picea abies (L.) Karst. varying in age from 40 to 140 years, in tree density from 1680 to 320 trees ha(-1), and in tree height from 15 to 30 m. Structural parameters were measured by biomass harvests of individual trees and stand biometry. We estimated E(c) from scaled-up xylem sap flux of trees, and canopy-level fluxes were predicted by a three-dimensional microclimate and gas exchange model (STANDFLUX). In contrast to pine species, A(L)/A(S) of P. abies increased with stand age from 0.26 to 0.48 m(2) cm(-2). Agreement between E(c) derived from scaled-up sap flux and modeled canopy transpiration was obtained with the same parameterization of needle physiology independent of stand age. Reduced light interception per leaf area and, as a consequence, reductions in net canopy photosynthesis (A(c)), canopy conductance (g(c)) and E(c) were predicted by the model in the older stands. Seasonal water-use efficiency (WUE = A(c)/E(c)), derived from scaled-up sap flux and stem growth as well as from model simulation, declined with increasing A(L)/A(S) and stand age. Based on the different behavior of age-related A(L)/A(S) in Norway spruce stands compared with other tree species, we conclude that WUE rather than A(L)/A(S) could represent a common age-related property of all species. We also conclude that, in addition to hydraulic limitations reducing carbon gain in old stands, a functional change in A(L)/A(S) that is related to reduced light interception per leaf area provides another potential explanation for reduced carbon gain in old stands of P. abies, even when hydraulic constraints increase in response to changes in canopy architecture and aging.

Effects of systemic arterial hypoperfusion on splanchnic hemodynamics and hepatic arterial buffer response in pigs.

The hepatic arterial buffer response (HABR) tends to maintain liver blood flow under conditions of low mesenteric perfusion. We hypothesized that systemic hypoperfusion impairs the HABR. In 12 pigs, aortic blood flow was reduced by cardiac tamponade to 50 ml. kg(-1). min(-1) for 1 h (short-term tamponade) and further to 30 ml. kg(-1). min(-1) for another hour (prolonged tamponade). Twelve pigs without tamponade served as controls. Portal venous blood flow decreased from 17 +/- 3 (baseline) to 6 +/- 4 ml. kg(-1). min(-1) (prolonged tamponade; P = 0.012) and did not change in controls, whereas hepatic arterial blood flow decreased from 2 +/- 1 (baseline) to 1 +/- 1 ml. kg(-1). min(-1) (prolonged tamponade; P = 0.050) and increased from 2 +/- 1 to 4 +/- 2 ml. kg(-1). min(-1) in controls (P = 0.002). The change in hepatic arterial conductance (DeltaC(ha)) during acute portal vein occlusion decreased from 0.1 +/- 0.05 (baseline) to 0 +/- 0.01 ml. kg(-1). min(-1). mmHg(-1) (prolonged tamponade; P = 0.043). In controls, DeltaC(ha) did not change. Hepatic lactate extraction decreased, but hepatic release of glutathione S-transferase A did not change during cardiac tamponade. In conclusion, during low systemic perfusion, the HABR is exhausted and hepatic function is impaired without signs of cellular damage.