Expression of CD11c and EMR2 on neutrophils: potential diagnostic biomarkers for sepsis and systemic inflammation.

There is a need for cellular biomarkers to differentiate patients with sepsis from those with the non-infectious systemic inflammatory response syndrome (SIRS). In this double-blind study we determined whether the expression of known (CD11a/b/c, CD62L) and putative adhesion molecules [CD64, CD97 and epidermal growth factor (EGF)-like molecule containing mucin-like hormone receptor (EMR2)] on blood neutrophils could serve as useful biomarkers of infection and of non-infectious SIRS in critically ill patients. We studied 103 patients with SIRS, 83 of whom had sepsis, and 50 healthy normal subjects, using flow cytometry to characterize neutrophils phenotypically in whole blood samples. Patients with SIRS had an increased prevalence of neutrophils expressing CD11c, CD64 and EMR2 in comparison with healthy subjects (P < 0.001), but normal expression of CD11a, CD11b, CD62L and CD97. An increase in the percentage of neutrophils bearing CD11c was associated with sepsis, EMR2 with SIRS and CD64 with sepsis and SIRS. Neutrophils expressing CD11c had the highest sensitivity (81%) and specificity (80%) for the detection of sepsis, and there was an association between the percentage of neutrophils expressing EMR2 and the extent of organ failure (P < 0.05). Contrary to other reports, we did not observe an abnormal expression of CD11b or CD62L on neutrophils from patients with SIRS, and suggest that this discrepancy is due to differences in cell processing protocols. We propose that blood neutrophils expressing CD11c and EMR2 be considered as potential biomarkers for sepsis and SIRS, respectively.

Beyond the randomized clinical trial: citrate for continuous renal replacement therapy in clinical practice.

BACKGROUND: Premature circuit clotting is a major problem during continuous renal replacement therapy (CRRT). Six randomized controlled trials confirmed that regional anticoagulation with citrate is superior to heparin. Our objective was to compare circuit patency with citrate, heparin and epoprostenol in routine clinical practice. METHODS: We retrospectively analysed data on circuit patency of all circuits used in a single centre between September 2008 and August 2009. We differentiated between premature filter clotting, elective discontinuation and waste. RESULTS: 309 patients were treated with CRRT (n = 2,059 circuits). The mean age was 65.7; 63.8% were male. The methods to maintain circuit patency were unfractionated heparin (42.3%), epoprostenol (23.0%), citrate (14.7%), combinations of different anticoagulants (14.6%) and no anticoagulation (4.7%). Premature clotting was the most common reason for circuit discontinuation among circuits anticoagulated with heparin, epoprostenol or combinations of different anticoagulants (59-62%). Among circuits anticoagulated with citrate the main reason for discontinuation was elective (61%). Hazard regression analysis confirmed significantly better circuit survival with citrate. Changing from heparin to citrate decreased the risk of premature circuit clotting by 75.8%. CONCLUSION: In routine clinical practice, regional anticoagulation with citrate is associated with significantly better circuit patency than heparin or epoprostenol.

Multiannual observations of acetone, methanol, and acetaldehyde in remote tropical atlantic air: implications for atmospheric OVOC budgets and oxidative capacity.

Oxygenated volatile organic compounds (OVOCs) in the atmosphere are precursors to peroxy acetyl nitrate (PAN), affect the tropospheric ozone budget, and in the remote marine environment represent a significant sink of the hydroxyl radical (OH). The sparse observational database for these compounds, particularly in the tropics, contributes to a high uncertainty in their emissions and atmospheric significance. Here, we show measurements of acetone, methanol, and acetaldehyde in the tropical remote marine boundary layer made between October 2006 and September 2011 at the Cape Verde Atmospheric Observatory (CVAO) (16.85° N, 24.87° W). Mean mixing ratios of acetone, methanol, and acetaldehyde were 546 ± 295 pptv, 742 ± 419 pptv, and 428 ± 190 pptv, respectively, averaged from approximately hourly values over this five-year period. The CAM-Chem global chemical transport model reproduced annual average acetone concentrations well (21% overestimation) but underestimated levels by a factor of 2 in autumn and overestimated concentrations in winter. Annual average concentrations of acetaldehyde were underestimated by a factor of 10, rising to a factor of 40 in summer, and methanol was underestimated on average by a factor of 2, peaking to over a factor of 4 in spring. The model predicted summer minima in acetaldehyde and acetone, which were not apparent in the observations. CAM-Chem was adapted to include a two-way sea-air flux parametrization based on seawater measurements made in the Atlantic Ocean, and the resultant fluxes suggest that the tropical Atlantic region is a net sink for acetone but a net source for methanol and acetaldehyde. Inclusion of the ocean fluxes resulted in good model simulations of monthly averaged methanol levels although still with a 3-fold underestimation in acetaldehyde. Wintertime acetone levels were better simulated, but the observed autumn levels were more severely underestimated than in the standard model. We suggest that the latter may be caused by underestimated terrestrial biogenic African primary and/or secondary OVOC sources by the model. The model underestimation of acetaldehyde concentrations all year round implies a consistent significant missing source, potentially from secondary chemistry of higher alkanes produced biogenically from plants or from the ocean. We estimate that low model bias in OVOC abundances in the remote tropical marine atmosphere may result in up to 8% underestimation of the global methane lifetime due to missing model OH reactivity. Underestimation of acetaldehyde concentrations is responsible for the bulk (∼70%) of this missing reactivity.

Metabolic effects of intensive insulin therapy in critically ill patients.

Our aim was to investigate the effects of glycemic control and insulin concentration on lipolysis, glucose, and protein metabolism in critically ill medical patients. For our methods, the patients were studied twice. In study 1, blood glucose (BG) concentrations were maintained between 7 and 9 mmol/l with intravenous insulin. After study 1, patients entered one of four protocols for 48 h until study 2: low-insulin high-glucose (LIHG; variable insulin, BG of 7-9 mmol/l), low-insulin low-glucose (LILG; variable insulin of BG 4-6 mmol/l), high-insulin high-glucose [HIHG; insulin (2.0 mU . kg(-1).min(-1) plus insulin requirement from study 1), BG of 7-9 mmol/l], or high-insulin low-glucose [HILG; insulin (2.0 mU.kg(-1).min(-1) plus insulin requirement from study 1), BG of 4-6 mmol/l]. Age-matched healthy control subjects received two-step euglycemic hyperinsulinemic clamps achieving insulin levels similar to the LI and HI groups. In our results, whole body proteolysis was higher in patients in study 1 (P < 0.006) compared with control subjects at comparable insulin concentrations and was reduced with LI (P < 0.01) and HI (P = 0.001) in control subjects but not in patients. Endogenous glucose production rate (R(a)), glucose disposal, and lipolysis were not different in all patients in study 1 compared with control subjects at comparable insulin concentrations. Glucose R(a) and lipolysis did not change in any of the study 2 patient groups. HI increased glucose disposal in the patients (HIHG, P = 0.001; HILG, P = 0.07 vs. study 1), but this was less than in controls receiving HI (P < 0.03). In conclusion, low-dose intravenous insulin administered to maintain BG between 7-9 mmol/l is sufficient to limit lipolysis and endogenous glucose R(a) and increase glucose R(d). Neither hyperinsulinemia nor normoglycemia had any protein-sparing effect.

Promoting Global Research Excellence in Severe Sepsis (PROGRESS): lessons from an international sepsis registry.

BACKGROUND: The PROGRESS Registry (Promoting Global Research Excellence in Severe Sepsis) was designed to provide comparative data reflecting everyday clinical practice, thereby allowing participating institutions to explore and benchmark medical interventions in severe sepsis. MATERIALS AND METHODS: PROGRESS was an international, noninterventional, prospective, observational registry collecting data that describe the management and outcomes of severe sepsis patients in intensive care units (ICUs). Patients were enrolled who had been diagnosed with severe sepsis (suspected or proven infection and >or= 1 acute sepsis-induced organ dysfunction) at the participating institutions, where de-identified data were entered directly into a secured website. PROGRESS was governed by an independent international medical advisory board. RESULTS: PROGRESS took place in 276 ICUs in 37 countries, and 12,881 patients were identified as having severe sepsis. There was considerable variation among countries in enrollment levels, provision of standard treatment and supportive therapies, and ICU and hospital outcomes. Eight countries accounted for 65.2% of the enrolled patients. Males (59.3%) and Caucasian (48.6%) patients predominated the patient cohort. Diagnosis of severe sepsis was prior to ICU admission in 45.7% of patients, at ICU admission in 29.1% of patients, and after ICU admission in the remainder. Globally, ICU and hospital mortality rates were 39.2% and 49.6%, respectively. The mean length of ICU and hospital stay was 14.6 days and 28.2 days, respectively. CONCLUSIONS: The PROGRESS international sepsis registry demonstrates that a large web-based sepsis registry is feasible. Wide variations in outcomes and use of sepsis therapies were observed between countries. These results also suggest that additional opportunities exist across countries to improve severe sepsis outcomes.

Factors influencing the effectiveness of endovenous laser ablation (EVLA) in the treatment of great saphenous vein reflux.

OBJECTIVE: Endovenous laser ablation (EVLA) is an alternative to surgery for treating sapheno-femoral and great saphenous vein (GSV) reflux. This study assesses factors that might influence its effectiveness. DESIGN: Prospective, observational study. METHOD: EVLA was used to treat the great saphenous vein in 644 limbs as part of the management of varicose veins. Body mass index (BMI), maximum GSV diameter, length of vein treated, total laser energy (TLE) and energy density (ED: Joules/cm) delivered were recorded prospectively. Data from limbs with ultrasound confirmed GSV occlusion at 3-months were compared with those where the GSV was partially occluded or patent. Complications were recorded prospectively. RESULTS: GSV occlusion was achieved in 599/644 (93%) limbs (group A). In 45 limbs (group B) the vein was partially occluded (n=19) or patent (n=26). Neither BMI [group A: 25.2 (23.0-28.5); group B: 25.1 (24.3-26.2)], nor GSV diameter [A: 7.2mm (5.6-9.2); B: 6.9 mm (5.5-7.7)] influenced success. TLE and ED were greater p<0.01) in group A (median [inter-quartile range]: 1877J (997-2350), 48 (37-59)J/cm) compared to group B (1191J (1032-1406), 37 (30-46)J/cm). Although TLE reflects the greater length of GSV ablated in Group A (33 cm v 29 cm, p=0.06) this does not influence ED. GSV occlusion always occurred when ED>/=60 J/cm with no increase in complications. CONCLUSIONS: ED (J/cm) of laser delivery is the main determinant of successful GSV ablation following EVLA.

Aunties and Uncles Co-operative Family Project: the experiences of children, volunteers and parents.

BACKGROUND: This paper reports on the experiences of the children (nieces and nephews), volunteers (aunts and uncles) and parents involved in the Aunties and Uncles Co-operative Family Project in Sydney, Australia. The project has run for 30 years as an extended family network of community volunteers and has never been evaluated. METHODS: A survey comprising open-ended and closed questions relating to the service was administered to all stakeholders. Demographic data were collected on all respondents. The text from answers to open-ended questions on the survey was coded for similarities and differences and was categorized. From the categories, the experiences of children, volunteers and parents were written with exemplars from the respondents' text. RESULTS: Three major categories emerged from the text: enjoyment/satisfaction of the experience for volunteers, children and parents; family relationships; and the difference it has made to me (children, parents and volunteers). CONCLUSIONS: The long-term benefits of a supportive 'extended family type' relationship were recognized by all participants. Although the children were the primary focus of the project, parents and volunteers also described the rewards they experienced. The volunteer element was integral to providing the wide-ranging, ongoing supports which would not be possible from a paid staff basis.

Nerve excitability changes in critical illness polyneuropathy.

Patients in intensive care units frequently suffer muscle weakness and atrophy due to critical illness polyneuropathy (CIP), an axonal neuropathy associated with systemic inflammatory response syndrome and multiple organ failure. CIP is a frequent and serious complication of intensive care that delays weaning from mechanical ventilation and increases mortality. The pathogenesis of CIP is not well understood and no specific therapy is available. The aim of this project was to use nerve excitability testing to investigate the changes in axonal membrane properties occurring in CIP. Ten patients (aged 37-76 years; 7 males, 3 females) were studied with electrophysiologically proven CIP. The median nerve was stimulated at the wrist and compound action potentials were recorded from abductor pollicis brevis muscle. Strength-duration time constant, threshold electrotonus, current-threshold relationship and recovery cycle (refractoriness, superexcitability and late subexcitability) were recorded using a recently described protocol. In eight patients a follow-up investigation was performed. All patients underwent clinical examination and laboratory investigations. Compared with age-matched normal controls (20 subjects; aged 38-79 years; 7 males, 13 females), CIP patients exhibited reduced superexcitability at 7 ms, from -22.3 +/- 1.6% to -7.6 +/- 3.1% (mean +/- SE, P approximately 0.0001) and increased accommodation to depolarizing (P < 0.01) and hyperpolarizing currents (P < 0.01), indicating membrane depolarization. Superexcitability was reduced both in patients with renal failure and without renal failure. In the former, superexcitability correlated with serum potassium (R = 0.88), and late subexcitability was also reduced (as also occurs owing to hyperkalaemia in patients with chronic renal failure). In patients without renal failure, late subexcitability was normal, and the signs of membrane depolarization correlated with raised serum bicarbonate and base excess, indicating compensated respiratory acidosis. It is inferred that motor axons in these CIP patients are depolarized, in part because of raised extracellular potassium, and in part because of hypoperfusion. The chronic membrane depolarization may contribute to the development of neuropathy.

pRotective vEntilation with veno-venouS lung assisT in respiratory failure: A protocol for a multicentre randomised controlled trial of extracorporeal carbon dioxide removal in patients with acute hypoxaemic respiratory failure.

One of the few interventions to demonstrate improved outcomes for acute hypoxaemic respiratory failure is reducing tidal volumes when using mechanical ventilation, often termed lung protective ventilation. Veno-venous extracorporeal carbon dioxide removal (vv-ECCO2R) can facilitate reducing tidal volumes. pRotective vEntilation with veno-venouS lung assisT (REST) is a randomised, allocation concealed, controlled, open, multicentre pragmatic trial to determine the clinical and cost-effectiveness of lower tidal volume mechanical ventilation facilitated by vv-ECCO2R in patients with acute hypoxaemic respiratory failure. Patients requiring intubation and mechanical ventilation for acute hypoxaemic respiratory failure will be randomly allocated to receive either vv-ECCO2R and lower tidal volume mechanical ventilation or standard care with stratification by recruitment centre. There is a need for a large randomised controlled trial to establish whether vv-ECCO2R in acute hypoxaemic respiratory failure can allow the use of a more protective lung ventilation strategy and is associated with improved patient outcomes.

Use of selective digestive tract decontamination in European intensive cares: the ifs and whys.

BACKGROUND: Several studies have shown that the use of selective digestive tract decontamination (SDD) reduces mortality. However, fear for increasing multidrug resistance might prevent wide acceptance. A survey was performed among the units registered in the European Registry for Intensive Care (ERIC), in order to investigate the number of ICUs using SDD and the factors that prevented the use of SDD. METHODS: One invitation to the electronic survey was sent to each ERIC unit. The survey focused on department characteristics (intensive care type, local resistance levels), local treatment modalities (antibiotic stewardship) and doctors' opinions (collaborative issues concerning SDD). All ICU's in countries participating in the European Centre for Disease Prevention and Control resistance surveillance program were analysed. RESULTS: Seventeen percent of the ICUs registered in the ERIC database used SDD prophylaxis. Most of these ICUs were located in the Netherlands or Germany. ICUs using SDD were four times more likely to use antibiotic stewardship. Also larger ICUs were more likely to use SDD. On the contrary, resistance to antibiotics was not related to the use of SDD. Also the doctor's opinion that SDD is proven in cluster-randomized trials was not a determinant for not using SDD. CONCLUSION: SDD is used in a minority of the European ICUs registered in the ERIC database. Larger ICUs and ICUs with a prudent antibiotic policy were more likely to use SDD. Neither antibiotic resistance nor the cluster randomized study design were determinants of the non-use of SDD.

International survey on the management of mechanical ventilation during ECMO in adults with severe respiratory failure.

BACKGROUND: No consensus exists on the optimal settings of mechanical ventilation during veno-venous extracorporeal membrane oxygenation (ECMO). Our aim was to describe how mechanical ventilation and related interventions are managed by adult ECMO centres. METHODS: A cross-sectional, multi-centre, international survey of 173 adult respiratory ECMO centres. The survey was generated through an iterative process and assessed for clarity, content and face validity. RESULTS: One hundred thirty-three centres responded (76.8%). Pressure control was the most commonly used mechanical ventilation mode (64.4%). Although the median PEEP was 10 cmH2O, 22.6% set PEEP <10 cmH2O and 15.5% used 15-20 cmH2O. In 63% of centres PEEP was fixed and not titrated. Recruitment maneuvres, were never used in 34.1% of centres, or used daily in 13.2%. Centres reported using either a "lung rest" (45.7%), or an "open lung" strategy (44.2%). Only 24.8% used chest CT to guide mechanical ventilation. Adjunctive treatments were never or occasionally used. Only 10% of centres extubated patients on ECMO, mainly in more experienced centres. 71.3% of centres performed tracheostomy on ECMO, with large variability in timing (most frequent on days 6-10). Only 27.1% of ECMO centres had a protocol for mechanical ventilation on ECMO. CONCLUSION: We found large variability in ventilatory practices during ECMO. The clinicians' training background and the centres' experience had no influence on the approach to ventilation. This survey shows that well conducted studies are necessary to determine the best practice of mechanical ventilation during ECMO and its impact on patient outcome.

Liver function and splanchnic ischemia in critically ill patients.

STUDY OBJECTIVE: To investigate the concept that splanchnic ischemia leads to hepatic dysfunction in the critically ill. DESIGN: Prospective study and analysis of patient data. SETTING: A general ICU in an inner-city London teaching hospital. PATIENTS: Twenty-seven consecutive critically ill patients with evidence of inadequate tissue perfusion requiring pulmonary artery catheterization and mechanical ventilation. MEASUREMENTS: In all patients, we measured the hepatic metabolism of lidocaine (lignocaine) to monoethylglycinexylidide (MEGX) and the clearance of indocyanine green (both dynamic, flow-dependent tests of hepatic function) over the first 3 days following admission to the ICU. These were compared with results of standard liver function tests and related to tonometric assessment of gastric intramucosal pH (pHim) and outcome. RESULTS: There were no significant differences in bilirubin, aspartate aminotransferase, alkaline phosphatase, and prothrombin levels, or in indocyanine green clearance between survivors and nonsurvivors. On day 3, the median MEGX level was higher in survivors than in nonsurvivors (16 vs 2.4 ng/mL, p < 0.001), and the median MEGX level in nonsurvivors fell over the 3 days (20.6 to 2.4 ng/mL, p < 0.002). MEGX levels were significantly correlated with pHim (Spearman rank correlation coefficient [Rs] = 0.69, p < 0.001) as were the changes in the two measurements over the 3 days (Rs = 0.46, p < 0.02). The MEGX formation test and gastric pHim were the most discriminatory with regard to death and survival. CONCLUSIONS: Our findings suggest that critically ill patients develop significant hepatic dysfunction that is associated with a poor outcome. This is likely to be due to a mismatch between hepatic metabolic demand and blood flow, and the MEGX formation test appears to be an extremely effective means of assessing liver function and flow in this group of patients.

Localization of the Thy-1 antigen to the surfaces of rat retinal ganglion cells.

Indirect immunofluorescence has been used to localize the Thy-1 antigen to ganglion cell axons, the ganglion cell layer and the inner plexiform layer in cryostat sections of adult and neonatal rat retina. In similar immunofluorescence experiments monoclonal antibodies raised against the 200,000 molecular weight neurofilament polypeptide bound only to ganglion cell axons and processes in the outer plexiform layer. Less than 1% of cells dissociated from 8 day postnatal rat retina had superficial Thy-1 antigen demonstrable by immunofluorescence; these cells were generally large and their size spectrum was similar to that of ganglion cells in situ . After culture for 1 day many of these Thy-1 positive cells had generated neurofilament antigen. We conclude that Thy-1 is found chiefly or exclusively on ganglion cells of eight day retina, and may be useful in the identification and isolation of these cells by immunoselection procedures.

Enriched populations of rat retinal ganglion cells: Studies using a cell-type specific surface marker.

Cells dissociated from adult and neonatal rat retinas were separated by density gradient centrifugation. Previous work had shown that rat retinal cells labelled by an immunofluorescence assay for the Thy-1 antigen were chiefly or exclusively ganglion cells, and so the proportion of Thy-1 positive cells in the density gradient fractions was used as an index of the enrichment of ganglion cells. The proportion of Thy-1 positive neonatal cells was increased from about 0.4% in the initial dissociate to about 8% in the most enriched fraction of a Percoll step gradient. Amongst adult cells the initial 0.7% Thy-1 positive cells were increased to roughly 2% in the best fraction of a metrizamide step gradient. The presence of relatively large numbers of Thy-1 positive cells in other fractions suggested that it would be difficult to further increase the proportion of rat ganglion cells by methods based on their sedimentation properties. These results demonstrate the importance of cell-type specific markers in attempts to purify cells from the central nervous system.

Cardiac function after intermittent antegrade warm blood cardioplegia: contribution of the double-indicator dilution technique.

OBJECTIVE: To evaluate cardiac performance following coronary artery surgery using two different techniques of cardioplegia. DESIGN: Randomized prospective study. SETTING: Adult cardiothoracic intensive care unit in a university hospital. STUDY POPULATION: Thirty patients undergoing isolated coronary surgery. INTERVENTIONS: Patients were randomized to receive either intermittent antegrade warm blood cardioplegia with normothermic bypass (group 1) or combined antegrade and retrograde cold crystalloid cardioplegia with hypothermic bypass (group 2). Hemodynamic evaluation included conventional measurements from a pulmonary artery catheter and data obtained by thermal dye dilution utilizing an arterial thermistor-tipped fiberoptic catheter. RESULTS: The only major difference between groups was a significantly higher right atrial pressure in group 2, from 4 h to 24 h after surgery (8.8 +/- 2.6 vs. 11.8 +/- 3.2 mmHg at 4 h and 11 +/- 3.1 vs. 8.5 +/- 1.8 mmHg at 24 h, P = 0.04). After cold cardioplegia a significant increase in right atrial pressure was observed (7.5 +/- 3.1 before surgery vs. 11.4 +/- 3 mmHg at 8 h, P = 0.003) whereas right ventricular end diastolic volume index did not increase significantly, suggesting impaired right ventricular diastolic compliance in this group. CONCLUSIONS: Until 24 h after surgery cold cardioplegia is associated with impaired right ventricular filling, which seems better preserved by intermittent antegrade warm blood cardioplegia. End-diastolic volume measurement with the double-indicator technique allows differentiation between systolic and diastolic dysfunction.

Assessment of cardiac preload and extravascular lung water by single transpulmonary thermodilution.

OBJECTIVE: Transpulmonary double-indicator dilution is a useful monitoring technique for measurement of intrathoracic blood volume (ITBV) and extravascular lung water (EVLW). In this study, we compared a simpler approach using single arterial thermodilution derived measurements of ITBV and EVLW with the double-indicator dilution technique. DESIGN: Prospective observational clinical study. SETTING: Surgical intensive care units of two university hospitals. PATIENTS AND METHODS: Global end-diastolic volume (GEDV) derived from single thermodilution was used for calculation of ITBV. Structural regression analysis of the first two thermo-dye dilution measurements in a derivation population of 57 critically ill patients (38 male, 19 female, 18-79 years, 56 +/- 15 years) revealed ITBV = (1.25 x GEDV)-28.4 (ml). This equation was then applied to all first measurements in a validation population of 209 critically ill patients (139 male, 70 female, 10-88 years, mean 53 +/- 19 years), and single-thermodilution ITBV (ITBV(ST)) and EVLW (EVLW(ST)) was calculated and compared to thermo-dye dilution derived values (ITBV(TD), EVLW(TD)). For inter-individual comparison, absolute values for ITBV and EVLW were normalised as indexed by body surface area (ITBVI) and body weight (EVLWI), respectively. MEASUREMENTS AND RESULTS: Linear regression analysis yielded a correlation of ITBVI(ST) = (1.05 x ITBVI(TD))-58.0 (ml/m2), r = 0.97, P < 0.0001. Bias between ITBVI(TD) and ITBVI(ST) was 7.6 (ml/m2) with a standard deviation of 57.4 (ml/m2). Single-thermodilution EVLWI (EVLWI(ST)) was calculated using ITBVI(ST) and revealed the correlation EVLWI(ST) = (0.83 x EVLWI(TD)) + 1.6 (ml/kg), r = 0.96, P < 0.0001. Bias between EVLWI(TD) and EVLWI(ST) was -0.2 (ml/kg) with a standard deviation of 1.4 (ml/kg). In detail, EVLWI(ST) systematically overestimated EVLWI(TD) at low-normal values for EVLWI and underestimated EVLWI at higher values (above 12 ml/kg). CONCLUSION: Determinations of ITBV and EVLW by single thermodilution agreed closely with the corresponding values from the double-indicator technique. Since transpulmonary single thermodilution is simple to apply, less invasive and cheaper, all these features make it a promising technique for the bedside. Nevertheless, further validation studies are needed in the future.

A simple perfusion chamber for studying neurotransmitter release from cells maintained in monolayer culture.

A perfusion chamber is described for studying the efflux of putative neurotransmitters from CNS cells maintained in monolayer culture. We have used this apparatus to investigate the efflux of newly accumulated [3H]GABA from cell cultures of the early postnatal rat cerebellum.

Selective uptake of tritiated glycine, GABA and D-aspartate by retinal cells in culture: a study using autoradiography and simultaneous immunofluorescence.

Autoradiographic studies on the uptake of 3 tritiated amino acids by cell cultures of rat retina are reported. At 0.2 microM [3H]-GABA is taken up with great selectivity by a minority of medium to large multipolar cells. At 2 microM [3H]glycine is taken up with slightly less selectivity by a similar proportion of multipolar cells; the proportions of cells labeled by either amino acid are additive which indicates that they are separate populations. In simultaneous autoradiographical and indirect immunofluorescence experiments, both of these cell classes were found to bind tetanus toxin and are therefore presumably neurons. At 0.4 microM [3H]D-aspartate is preferentially taken up by virtually all small spheroid cells which lack long processes (putative immature photoreceptors), as well as by a minority of larger multipolar cells. All 3 tritiated amino acids also label flattened cells which include retinal glia. The results are discussed in relation to similar experiments performed on undissociated retina and we conclude that these experiments allow us to identify and quantify immature photoreceptors and certain sub-types of amacrine cells in these cultures.