Hot Deformation and Microstructure Evolution of Metallic Materials

Hot plastic deformation is a key method of processing metallic materials and controlling their final properties through structure-forming processes [...].

Analysis of the Microstructure Development of Nb-Microalloyed Steel during Rolling on a Heavy-Section Mill

It is not realistic to optimize the roll pass design of profile rolling mills, which typically roll hundreds of profiles, using physical modelling or operational rolling. The use of reliable models of microstructure evolution is preferable here. Based on the mathematical equations describing the microstructure evolution during hot rolling, a modified microstructure evolution model was presented that better accounts for the influence of strain-induced precipitation (SIP) on the kinetics of static recrystallization. The time required for half of the structure to soften, t_0.5, by static recrystallization was calculated separately for both situations in which strain-induced precipitation occurred or did not occur. On this basis, the resulting model was more sensitive to the description of grain coarsening in the high-rolling-temperature region, which is a consequence of the rapid progress of static recrystallization and the larger interpass times during rolling on cross-country and continuous mills. The modified model was verified using a plain strain compression test (PSCT) simulation of rolling a 100-mm-diameter round bar performed on the Hydrawedge II hot deformation simulator (HDS-20). Four variants of simulations were performed, differing in the rolling temperature in the last four passes. For comparison with the outputs of the modified model, an analysis of the austenite grain size after rolling was performed using optical metallography. For indirect comparison with the model outputs, the SIP initiation time was determined based on the NbX precipitate size distribution obtained by TEM. Using the PSCT and the outputs from the modified microstructure evolution model, it was found that during conventional rolling, strain-induced precipitation occurs after the last pass and thus does not affect the austenite grain size. By lowering the rolling temperature, it was possible to reduce the grain size by up to 56 μm, while increasing the mean flow stress by a maximum of 74%. The resulting grain size for all four modes was consistent with the operating results.

Hot Deformation Behavior of Non-Alloyed Carbon Steels

The hot deformation behavior of selected non-alloyed carbon steels was investigated by isothermal continuous uniaxial compression tests. Based on the analysis of experimentally determined flow stress curves, material constants suitable for predicting peak flow stress σ_p, peak strain ε_p and critical strain ε_crDRX necessary to induce dynamic recrystallization and the corresponding critical flow stresses σ_crDRX were determined. The validity of the predicted critical strains ε_crDRX was then experimentally verified. Fine dynamically recrystallized grains, which formed at the boundaries of the original austenitic grains, were detected in the microstructure of additionally deformed specimens from low-carbon investigated steels. Furthermore, equations describing with perfect accuracy a simple linear dependence of the critical strain ε_crDRX on peak strain ε_p were derived for all investigated steels. The determined hot deformation activation energy Q decreased with increasing carbon content (also with increasing carbon equivalent value) in all investigated steels. A logarithmic equation described this dependency with reasonable accuracy. Individual flow stress curves of the investigated steels were mathematically described using the Cingara and McQueen model, while the predicted flow stresses showed excellent accuracy, especially in the strains ranging from 0 to ε_p.

Effects of Austenitization Temperature and Pre-Deformation on CCT Diagrams of 23MnNiCrMo5-3 Steel

The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in the range suitable for the wire rolling mill. The applied compressive deformation corresponded to the true strain values in an unusually wide range. Based on the dilatometric tests and metallographic analyses, a total of five different CCT diagrams were constructed. Pre-deformation corresponding to the true strain of 0.35 or even 1.0 had no clear effect on the austenite decomposition kinetics at the austenitization temperature of 880 °C. During the long-lasting cooling, recrystallization and probably coarsening of the new austenitic grains occurred, which almost eliminated the influence of pre-deformation on the temperatures of the diffusion-controlled phase transformations. Decreasing the deformation temperature to 830 °C led to the significant acceleration of the austenite → ferrite and austenite → pearlite transformations due to the applied strain of 1.0 only in the region of the cooling rate between 3 and 35 °C·s^-1. The kinetics of the bainitic or martensitic transformation remained practically unaffected by the pre-deformation. The acceleration of the diffusion-controlled phase transformations resulted from the formation of an austenitic microstructure with a mean grain size of about 4 µm. As the analysis of the stress-strain curves showed, the grain refinement was carried out by dynamic and metadynamic recrystallization. At low cooling rates, the effect of plastic deformation on the kinetics of phase transformations was indistinct.

Correlation among the Power Dissipation Efficiency, Flow Stress Course, and Activation Energy Evolution in Cr-Mo Low-Alloyed Steel

In the presented research, conventional hot processing maps superimposed over the flow stress maps or activation energy maps are utilized to study a correlation among the efficiency of power dissipation, flow stress, and activation energy evolution in the case of Cr-Mo low-alloyed steel. All maps have been assembled on the basis of two flow curve datasets. The experimental one is the result of series of uniaxial hot compression tests. The predicted one has been calculated on the basis of the subsequent approximation procedure via a well-adapted artificial neural network. It was found that both flow stress and activation energy evolution are capable of expressing changes in the studied steel caused by the hot compression deformation. A direct association with the course of power dissipation efficiency is then evident in the case of both. The connection of the presence of instability districts to the activation energy evolution, flow stress course, and power dissipation efficiency was discussed further. Based on the obtained findings it can be stated that the activation energy processing maps represent another tool for the finding of appropriate forming conditions and can be utilized as a support feature for the conventionally-used processing maps to extend their informative ability.

Visuospatial neglect in near and far space: dissociation between line bisection and letter cancellation

The differential performance on a line bisection and a cancellation task in near and far space was studied. A group of 10 patients with severe left-sided visuospatial neglect and a group of 10 right-brain damaged patients without neglect were examined. The stimuli were presented at a distance of 60 cm (near space) and 160 cm (far space), respectively, and corrected for visual angle. In the line bisection task, patients were asked to point to the estimated line centre with a pencil (near space) or a stick (far space). In the cancellation task, patients pointed to all target stimuli they could detect using either a pencil (near space) or a stick (far space). Most patients with left hemineglect showed a more prominent neglect in far space as compared to near space for the line bisection task, whereas no difference of performance between near and far space was found in the control patients. In contrast, no group showed a distance effect in the cancellation task. The observation that only line bisection is influenced by the distance of the stimulus suggests that line bisection and cancellation are processed differentially. It is proposed that line bisection requires an allocentric reference system focusing attention on objects, whereas cancellation tasks are based on an egocentric reference system responsible for visuospatial attention. Our results indicate that distance changes perception within the allocentric but not within the egocentric system.

Dixyrazine for the prevention of postoperative nausea and vomiting after laparoscopic cholecystectomy

BACKGROUND

The study assessed the efficacy and safety of dixyrazine, an alternative neuroleptic drug to droperidol, in the prophylaxis of postoperative nausea and vomiting (PONV).

METHODS

A total of 197 patients scheduled for laparoscopic cholecystectomy under general anesthesia were randomized to receive either dixyrazine 10 mg or placebo double-blinded at the end of surgery. Scores pertaining to PONV episodes, analgetic supply, rescue medication, adverse events and patient satisfaction were collected over the first 2 h in the PACU and the next 22 h in the ward.

RESULTS

The incidence of PONV over the entire 24-h period was reduced from 32% in the placebo group to 13% in the dixyrazine group (P< or =0.004). The incidence of nausea in the first 2 h was reduced from 15% in the placebo group to 4% in the dixyrazine group (P< or =0.02) and from 12% to 5% in the next 22 h. The incidence of emetic episodes was not different between the two groups. Postoperative shivering was significantly less prevalent in the dixyrazine than in the placebo group (2% vs. 13%; P< or =0008), and opioid analgesics were required significantly less often (61% vs. 75%; P< or =0.01). No significant adverse effects were observed. Patient satisfaction was similar in both groups.

CONCLUSION

Prophylactic dixyrazine is an effective, safe, and cheap antiemetic drug for laparoscopic cholecystectomy without involving any significant adverse events.

Avoidance of obstacles in the absence of visual awareness

The spatial character of our reaching movements is extremely sensitive to potential obstacles in the workspace. We recently found that this sensitivity was retained by most patients with left visual neglect when reaching between two objects, despite the fact that they tended to ignore the leftward object when asked to bisect the space between them. This raises the possibility that obstacle avoidance does not require a conscious awareness of the obstacle avoided. We have now tested this hypothesis in a patient with visual extinction following right temporoparietal damage. Extinction is an attentional disorder in which patients fail to report stimuli on the side of space opposite a brain lesion under conditions of bilateral stimulation. Our patient avoided obstacles during reaching, to exactly the same degree, regardless of whether he was able to report their presence. This implicit processing of object location, which may depend on spared superior parietal-lobe pathways, demonstrates that conscious awareness is not necessary for normal obstacle avoidance.

Validation of an ESI-MS/MS screening method for acylcarnitine profiling in urine specimens of neonates, children, adolescents and adults

BACKGROUND

Acylcarnitine (AC) profiling in dried blood spots by means of electrospray ionisation tandem mass spectrometry (ESI-MS/MS) has proven to be a useful method in neonatal screening, able to detect inborn errors of fatty acid oxidation, amino acid, organic acid and carnitine metabolism. Furthermore, this method is becoming increasingly applied in selective screening and in prenatal and postmortal diagnostics of inborn metabolic disorders, where urine is commonly used as specimen of interest. We therefore developed and validated a butylation method of acylcarnitine profiling in urine by ESI-MS/MS without previous chromatographic separation.

METHODS

Random urine specimens were used for investigation of the analytical imprecision of the method. Recovery, precision and linearity were determined using methanolic standard solutions of free carnitine, octanoylcarnitine and palmitoylcarnitine at various concentrations.

RESULTS

The mean coefficients of variation of within-run and run-to-run analysis of these analytes were found between 10% and 20% and demonstrated that the method fulfills the analytical requirements within the relevant ranges of concentration. Creatinine-related and age-related reference values of free carnitine and the ACs (C2-C18) were established. The definite discrimination was possible between patients with fatty acid oxidation disorders, organic acidurias, and healthy controls. The AC profiles from patients with various specific disorders were diagnostically helpful during acute deterioration and even during conditions of well-compensated metabolic state.

CONCLUSION

The method used in this study is suitable both for selective screening and for confirmation of diagnosis with the advantage of high-throughput quantitative measurement.

Neck muscle vibration induces lasting recovery in spatial neglect

OBJECTIVES

To evaluate whether neck muscle vibration is an effective technique for neglect rehabilitation, with lasting beneficial effects.

METHODS

The effects of differential treatment of visual exploration training alone or in combination with neck muscle vibration were evaluated in a crossover study of two matched groups of 10 patients suffering from left sided neglect. Each group received a sequence of 15 consecutive sessions of exploration training and combined treatment. The effects of treatment were assessed with respect to different aspects of the neglect disorder such as impaired perception of the egocentric midline, exploration deficits in visual and tactile modes, and visual size distortion. The transfer of treatment effects to activities of daily living was examined by a reading test and a questionnaire of neglect related everyday problems. All variables were measured six times: three baseline measurements, two post-treatment measurements, and one follow up after two months.

RESULTS

The results showed superior effects of combination treatment. A specific and lasting reduction in the symptoms of neglect was achieved in the visual mode, which transferred to the tactile mode with a concomitant improvement in activities of daily living. The improvement was evident two months after the completion of treatment. In contrast, isolated exploration training resulted in only minor therapeutic benefits in visual exploration without any significant transfer effects to other tasks.

CONCLUSIONS

Neck muscle vibration is a decisive factor in the rehabilitation of spatial neglect and induces lasting recovery when given as a supplement to conventional exploration training.

Activation of spinach pullulanase by reduction results in a decrease in the number of isomeric forms

Spinach starch debranching enzyme, a limit dextrinase or pullulanase (EC 3.2.1.41), is a monomeric protein of 100 kDa that produces up to seven coexisting and mutually interconvertible isomers of different specific activity, a phenomenon that has been termed microheterogeneity and for which a structural explanation has not yet been presented. The enzyme can be activated by reduction, in particular by thiol reagents, and inactivated by oxidation and the concomitant change of the patterns of its isomeric forms could be quantified by chromatofocusing. The hypothesis was examined that reduction of the enzyme's thiol groups shifts the isomer pattern towards the forms with a higher specific activity while oxidation favours the less active forms. Using TCEP as reductant only the form with the highest specific activity was obtained. This form was almost inaccessible for proteolysis by trypsin while the oxidized and GSH-activated enzyme yielded four peptides when treated with trypsin. Their sequence indicated cleavage predominantly of loops connecting the beta-strands and alpha-helices of the (beta/alpha)(8)-barrel which forms the catalytic site of the pullulanase. Formation of various disulphide bridges between the loops connecting the barrel structures -- predominantly on one side -- may be the reason for the microheterogeneity of the spinach pullulanase. In vivo, the enzyme maintains its activated state due to the high concentration of GSH in the chloroplast. However, the chloroplast's pH shifts from day (pH 8) to night (pH 7) and thus could also alter the activity of the protein in accordance with the required function in starch metabolism.

Neuroendocrine differentiation is a relevant prognostic factor in stage III-IV colorectal cancer

OBJECTIVE

To determine the prognostic relevance of neuroendocrine differentiation in colorectal cancer.

METHODS

The survival of 116 patients with colorectal cancer of stages III (n = 59) and IV (n = 57) was correlated with the extent of neuroendocrine differentiation. Chromogranin A and synaptophysin were used as neuroendocrine markers. Based on the degree of immunoreactivity for these markers, tumours were classified as 0 (no expression of neuroendocrine markers), 1 (< 2% cells staining positive for neuroendocrine markers) and 2 (> 2% cells staining positive for neuroendocrine markers). Patients were followed up for more than 5 years or until death.

RESULTS

Seven of 59 (11.8%) stage III cancers and 13/57 (22.8%) stage IV cancers belonged to group 2. The 96 patients of groups 0 and 1 lived for 48.9 months, whereas the 20 patients of group 2 survived for only 18.6 months (Kaplan-Meier survival curves, P < 0.001). The difference was most striking in stage III disease with 79.4 months' survival for combined groups 0 and 1, and 38.9 months' survival for group 2 (P < 0.01). Using the multivariate Cox regression model, the presence of more than 2% of cells with neuroendocrine differentiation was found to be an independent prognostic parameter for stage III and IV disease. No correlation was observed between neuroendocrine differentiation and tumour location, grade, depth of invasion or stage.

CONCLUSION

Neuroendocrine differentiation is often seen in colorectal cancer. It is an independent prognostic factor in stage III-IV colorectal cancer.

Different effects of valproic acid on proliferation and migration of malignant glioma cells in vitro

Valproic acid (VPA) has been considered as a possible treatment agent for malignant gliomas. In order to characterise the possibilities of VPA, we investigated the effects on cell migration and proliferation. Human cell lines T98G, A172, 85HG66 and 86HG39 were treated with VPA or left untreated, afterwards Boyden chamber assay was used for measuring vertical migration. In a second assay cells were stimulated to create spheroids and spheroid migration was measured. Proliferation was assessed using a cell counter. VPA decreased proliferation of 86HG39 > A172 > 85HG66 cells, whereas T98G remained uninfluenced. The influence of VPA on migration was different; whereas VPA dose-dependently stimulated migration of 86HG39 cells, migration of T98G and 85HG66 decreased, whereas A172 cells remained uninfluenced. Only 86HG39 and A172 cells created spheroids. In both cell lines Boyden-chamber-findings were confirmed by analysing the influence of VPA on spheroid migration. These non-uniform data demonstrate that the benefit of VPA in glioma treatment is not clear and needs further investigation.

Time-dependent inhibition of glioblastoma cell proliferation by dexamethasone

Because of the outstanding importance of the glucocorticoid Dexamethasone (DEX) as supportive therapy in the management of brain tumours, the direct effect of DEX on tumour cell proliferation is of particular interest. Previous in vitro studies led to contradictory results. To characterise more precisely the influence of DEX, we investigated the glioblastoma multiforme (GM) cell lines A172, T98G and 86HG39. Cells were treated with DEX concentrations ranging from 5 x 10(-9) to 5 x 10(-5) M from 24 to 240h under different treatment conditions. Influence of DEX on glioma cell viability was assessed daily for 5 days by MTT-assay: (I) with continuous DEX incubation (acute treatment), (II) in a recultivation period without DEX after 5 days of DEX pre-incubation (pre-treatment), (III) with continuous DEX incubation after 5 days of DEX pre-incubation (combination treatment). DEX acute treatment led to strongly decreased proliferation of A172 cells, whereas T98G and 86HG39 cells remained uninfluenced. In opposite, a time-delayed inhibition of cell proliferation was observed in all three cell lines after DEX pre-treatment. Combination treatment induced a significant increase of the inhibitory effect in A172 and T98G cells. These data show a variable, partial time-dependent inhibitory effect of DEX on the proliferation of GM cells and may open new treatment strategies for malignant brain tumours.

Visual background motion reduces size distortion in spatial neglect

Patients with visual neglect show deficits in horizontal size perception in their neglected hemispace, as previously reported. The present study examined whether this size distortion can be modulated by visual background motion to the left or right while the patient performs a visual size judgment task. Six neglect patients and six normal subjects were investigated with a psychophysical size judgment task. All neglect patients showed a significant perceptual underestimation of horizontal bars in their left hemispace expressed as an overestimation of horizontal object size in the baseline (no motion) condition. Slow visual motion of background stimuli towards the right, ipsilesional side aggravated the deficit slightly, but not significantly, whereas leftward background motion completely normalized the size distortion (in four cases) or even led to an overcompensation (in two cases). This facilitatory effect was specific as it was obvious for the constant errors in the size judgments, but not in their accuracy as reflected by unchanged difference thresholds. These results suggest that coherent background motion restores temporarily the disturbed perception and representation of horizontal object size in spatial neglect.

Effects of half the tidal volume during cardiopulmonary resuscitation on acid-base balance and haemodynamics in pigs

The effects of half the tidal volume during cardiopulmonary resuscitation (CPR) on haemodynamics, acid-base balance, and oxygenation were studied in anaesthetized pigs. The animals were ventilated with a mean tidal volume of 12.5 +/- 0.5 ml/kg at a rate of 14/minute resulting in a mean arterial pCO2 of 40 +/- 3 mmHg. They were randomly assigned to two groups: in one group ventilation was performed with half the pre-arrest tidal volume (50% group; n = 9), in the other group ventilation remained unchanged during CPR (100% group; n = 10). After 8 minutes of CPR attempts were made to restore spontaneous circulation with epinephrine and countershocks. There were no differences in advanced life support requirements, haemodynamic parameters, and resuscitability between the two groups. During CPR up to 5 minutes after restoration of spontaneous circulation (ROSC) dead space ventilation was significantly higher in the 50% group compared with the 100% group (p < 0.05). During CPR (at 3 and 7 minutes) arterial pO2 values were significantly lower (218 +/- 136 and 221 +/- 120 mmHg vs. 381 +/- 130 and 352 +/- 147 mmHg; FiO2 1.0) and hyperventilation was less pronounced (34.4 +/- 7.3 and 31.3 +/- 7.7 mmHg vs. 26.2 +/- 5.6 and 26.9 +/- 6.3 mmHg) in the 50% group. Our results suggest that half the tidal volume during CPR is likely to establish a more physiological acid-base balance and has no adverse effects on haemodynamics in intubated pigs ventilated with pure oxygen.

Protein heterogeneity of spinach pullulanase results from the coexistence of interconvertible isomeric forms of the monomeric enzyme

Purified pullulanase (starch-debranching enzyme, R-enzyme, EC 3.2.1. 41) from spinach (Spinacia oleracea L.) chloroplasts separated into at least seven individual enzymically active proteins (isomers, numbered 1-7) on isoelectric focusing or column chromatofocusing. At their isoelectric points (between pH 4.7 and 5.2) these forms were rather stable. At slightly alkaline pH, each converted into the whole set of isomers. PAGE of the purified enzyme under denaturing or non-denaturing conditions resulted in one protein band. When substrate (amylopectin or pullulan) was included in the gel, the native enzyme as well as any of the individual isomers separated into two (sometimes three) bands ('substrate-induced forms', numbered I-III) with different specific activities, dissociation constants of the enzyme-substrate complexes and activation energies. Each substrate-induced form produced the whole set of seven isomers on isoelectric focusing. The specific activity of the total enzyme reflected the relative proportions of the substrate-induced forms. To some extent the relative proportions, as determined by crossed immunoelectrophoresis, could be shifted in favour of the more or the less active forms by reduction with dithiothreitol, and gentle oxidation respectively. Activation by dithiothreitol did not alter the mode of action of the enzyme but only increased the velocity of substrate degradation and extended its activity into the pH range of the chloroplast. As a consequence of isomer interconversion, microheterogeneity could serve to regulate pullulanase activity in a biochemical manner that shares some features with allosteric regulation.

Head and trunk orientation modulate visual neglect

Five patients with left visual neglect after right hemisphere lesions were examined with a line bisection and a reading task under five different conditions: head and trunk straight ahead, head or trunk oriented 20 degrees to the left and head or trunk oriented 20 degrees to the right. Fixation was always straight ahead. Five patients with right hemisphere lesions but without neglect and five normal subjects served as controls. In all neglect patients, turning the head or trunk to the left reduced line bisection and reading errors significantly as compared with the other three conditions and with the control groups. The modulation of neglect behaviour by trunk as well as head position supports the hypothesis of a disturbed egocentric coordinate system leading to neglect.

[Hemi-neglect versus hemianopia. Differential diagnosis]

Neglect and hemianopia represent frequent disorders in brain damaged patients. Differential diagnosis of both disorders may be difficult since both may present in diagnostic tests and daily life as a failure to perceive or react to stimuli in the contralesional hemispace or hemifield. The present paper summarizes several useful techniques in order to achieve a correct distinction. After a short review of the clinical phenomenology of hemianopia and -neglect the following topics are described: (1) subjective complaints and awareness of deficits (2) aetiology and lesion localisation, (3) uni-versus multimodal deficits; (4) extinction, (5) drawing from memory; (6) visual-spatial disorders; (7) line bisection, (8) effectiveness of attentional "cueing" strategies; (9) specific perimetric techniques; (10) visual evoked potentials and eye movement registration. The differences between hemianopia and -neglect are contrasted for all these topics. Taken all these possible features together the association and/or dissociation of hemineglect and postchiasmatic scotomata can efficiently be diagnosed. The results are summarized in a table at the end of the paper.

Moderate induced hypotension provides satisfactory operating conditions in maxillofacial surgery

Patients scheduled for maxillofacial surgery were randomly assigned to receive isoflurane (n = 22) or nitroglycerin (n = 18) in order to induce hypotension. Surgeons, blinded for the actual level of blood pressure and the technique used for inducing hypotension, were asked to rate operating conditions on a scale from 1 to 5. Systolic arterial pressure (SAP) and mean arterial pressure (MAP) were reduced by 26% for both groups. Although blood pressure levels showed little variation throughout the induced hypotension period, scores of 2 to 5 were given significantly more often at incision and at 30 min compared to the following measuring points (P < 0.01). In total, the surgical field was rated significantly more often with a score of 1 and 2 than with a score of 3 to 5 (P < 0.01). A relation between score and SAP and/or MAP could not be found. There was also no relation between scores and the technique used for hypotension. Our data suggest that, with the exception of the first half hour of surgery, on average a SAP of 89 mmHg and a MAP of 65 mmHg were sufficient to produce satisfactory operating conditions.

Nimodipine after circulatory arrest: effects on oxygen delivery and consumption

PURPOSE

Evaluation of the effects of nimodipine administration during and after cardiopulmonary resuscitation (CPR) on oxygen delivery and consumption was the aim of this study.

METHODS

A randomized double-blind study in 32 anesthetized domestic pigs was performed. After 5 minutes of ventricular fibrillation (VF) and 5 minutes of external CPR, epinephrine (50 micrograms/kg) and either nimodipine or placebo (10 micrograms/kg bolus, 1 microgram/kg/min continuously throughout 4 hours of observation) were administered. One minute later (equal to 11 minutes VF), the first countershock was given. If this failed to restore spontaneous circulation, epinephrine and countershocks were repeated for a maximum of 30 minutes.

RESULTS

Eleven of 12 nimodipine- and 7 of 14 placebo-treated pigs could be resuscitated successfully and survived the observation period (P < .05). Hemodynamic responses to nimodipine were characterized by significant decreases in systemic vascular resistance and mean arterial pressure from 10 minutes after restoration of spontaneous circulation onwards with consequent significant increases in cardiac output. Median systemic oxygen delivery indices (DO2I) in nimodipine-treated pigs were significantly higher at all measuring points when compared with placebo-treated animals. Median systemic oxygen consumption indices (VO2I) did not differ significantly between groups. Median oxygen extraction ratios in nimodipine-treated pigs were in the same range as prearrest and were lower when compared with placebo-treated pigs (at 30 minutes P < .05 and at 120 minutes P < .01). DO2I and VO2I were poorly correlated in all pigs treated with nimodipine and in 3 of 7 animals treated with placebo, suggesting supply independency in these animals. This difference between groups was significant (P < .05).

CONCLUSIONS

Our findings suggest that in nimodipine-treated animals, a lower oxygen deficit or a better redistribution of regional blood flow occurred after circulatory arrest and resuscitation.

Effects of nimodipine on regional blood flow in heart and brain during cardiopulmonary resuscitation in pigs

The effect of nimodipine on organ blood flow during cardiopulmonary resuscitation (CPR) was studied in 26 anesthetized pigs. After 5 min of ventricular fibrillation circulatory arrest and 5 min of external CPR, all animals received 50 micrograms/kg of epinephrine and either nimodipine (10 micrograms/kg, followed by 1 microgram.kg-1.min-1 until termination of the experiment) or placebo. Organ blood flow was measured using radioactive-labeled microspheres. The rate of resuscitability in nimodipine-treated pigs (11 of 12) was significantly higher (P < 0.05) than in placebo-treated animals (7 of 14). In pigs receiving epinephrine and nimodipine, left ventricular blood flow after restoration of spontaneous circulation (ROSC) was approximately twice as high as in pigs receiving epinephrine and placebo (P < 0.01). In nimodipine-treated pigs, total cerebral blood flow 10 min after ROSC was significantly higher than baseline values (P < 0.01) and in hypophysis, cerebellum, and medulla the blood flows were significantly higher than in placebo-treated pigs (P < 0.05). We conclude that, in our pig model, high doses of nimodipine given during CPR caused significant enhancements in left ventricular blood flow and significantly improved the rate of resuscitation.

Effects of nimodipine administration during cardiopulmonary resuscitation in pigs

The haemodynamic effects of nimodipine during cardiopulmonary resuscitation (CPR) were investigated in 25 anaesthetized pigs. After 5 min of ventricular fibrillation (VF) and 5 min of closed-chest CPR, adrenaline (50 micrograms kg-1), either nimodipine (10 micrograms kg-1 as a bolus followed by 1 microgram kg-1 min-1 continuously) or the equivalent volume of placebo (solvent for nimodipine) were administered followed by the first countershock. If this failed to restore spontaneous circulation, adrenaline and countershocks were repeated for a maximum of 30 min. CPR was successful in nine out of 10 nimodipine-treated animals, but only in six out of 15 placebo-treated animals (P less than 0.02). In resuscitated pigs there were no significant differences in the number of countershocks, the number of seconds required for restoration of spontaneous circulation and the total doses of adrenaline required for both nimodipine and placebo pigs. After restoration of spontaneous circulation haemodynamic responses to nimodipine were characterized by decreases in systemic vascular resistance and mean arterial pressure with consequent increases in heart rate and cardiac output, but they were not significantly different from those of the placebo-treated animals. We therefore conclude that high doses of nimodipine are well tolerated during and after CPR; nimodipine administration may even result in higher initial CPR success rates. The underlying mechanisms need further investigation.

[Results of cardiopulmonary and cerebral resuscitation in the area of surgical intensive care]

In intensive care units specially trained staff and sophisticated technical equipment are confronted with extremely critically ill patients. In this patient population multiple organ failure is mostly established thus requiring application of all therapeutic facilities. During a study period of 40 months in 203 (86.4%) out of 235 patients with cardiac arrest a decision not to resuscitate ("DNR order") was made. In 32 patients cardiopulmonary resuscitation was attempted. Although spontaneous circulation could be maintained for at least 12 hours in 40.6% (13 patients), 6 died within the first day and 3 other patients died during the first week. Only 4 patients resuscitated could be discharged. Our data suggest that, despite further development of technical and therapeutic methods, the underlying disease has to be considered as the limitation of long-term survival.

[Comparative review of various resuscitation procedures]

During the last 10 years many experiments have confirmed the theory that blood flow during CPR likely occurs as a result of manipulation of intrathoracic pressure. In order to improve vital organ perfusion by increasing intrathoracic pressure many different techniques of CPR have been developed. These include "new CPR" (simultaneous ventilation and compression), asynchronous ventilation, prolonged compression, and continuous or interposed abdominal compression. Other methods like open chest CPR and the use of mechanized CPR or even cardiopulmonary bypass have also recently been proposed. All these techniques are reviewed in detail.

[Glucose-potassium-insulin in hypodynamic septic shock]

Haemodynamic and metabolic effects of glucose-potassium-insulin (GKI) were studied in 14 patients with peritonitis. Study entry criteria were: hypodynamic septic shock (mean arterial pressure less than 50 mmHg and cardiac index less than 3.5 l/min) despite a highly positive fluid balance (greater than +2,000 ml during the last 12 h) and use of catecholamines (greater than 15 mcg/kg/min Dobutamine). GKI (glucose 70% 1 g/kg + potassium 10 mval + insulin 1.5 U/kg) was infused within 15 min via a central venous catheter. Before and 10 min after GKI haemodynamic and metabolic measurements were performed. GKI led to significant increases in systolic (+53%) and mean (+61%) arterial pressures, cardiac index (+50%), right (+60%) and left (+109%) ventricular stroke work indices, and oxygen consumption index (+18%). Heart rate remained unchanged, pulmonary shunt fraction increased slightly, systemic and pulmonary vascular resistances showed an insignificant decline. Serum glucose (p less than 0.01) and pCO2 (p less than 0.1) increased. The haemodynamic improvement lasted from 30 min or less (n = 3; 21%) to several hours. Nine patients (64%) survived more than 2 days, and two patients (14%) were eventually discharged from the hospital. We conclude, that in hypodynamic septic shock refractory to volume loading and catecholamine treatment GKI may be beneficial, although the mechanism of action remains unclear.

[Evaluation of the thermal technic for the quantitative measurement of extravascular lung water]

To evaluate the accuracy of the method, sequential measurements (n = 159) of extravascular lung water (EVLW) using the thermo-dye double-indicator dilution technique were performed in 22 critically surgical ill patients. Radiographic grading of lung water content served as clinical standard. Normal mean EVLW defined radiographically without evidence of pulmonary edema was 4.8 +/- 1.1 ml/kg. Early interstitial fluid accumulation was quite accurately detected with 6.9 +/- 2.1 ml/kg EVLW (p less than 0.001 vs normal lung water content). The mean EVLW present with definitive interstitial and alveolar edema was 11.5 +/- 3.8 ml/kg and 19.1 +/- 4.5 ml/kg, respectively. Despite some objections to the method (diffusion limitation of the thermal indicator, uneven regional lung perfusion), this technique for measuring EVLW reliably assesses the degree of pulmonary edema. Even when properly performed, chest roentgenograms only confirm gross changes in the lung water content.

[Monitoring kidney function in abdominal infection]

In ICU patients suffering from abdominal sepsis acute renal failure (ARF) is a common (50% incidence) and often lethal (more than 80% mortality) complication. Continuous monitoring of renal function is necessary for both adequate fluid replacement and early detection of ARF. Using a programmable handheld computer the following parameters are calculated at least daily: creatinine, osmolal and free water clearance, fractional excretion of sodium and potassium and non-saline loss. The clearance values are corrected to 1.73 m2 body surface area. Free water clearance proved to be a particularly valuable guide for fluid therapy as well as for early diagnosis of ARF. In all septic patients renal function is impaired to some degree, since despite increased cardiac output creatinine clearance is only normal or even decreased. More than 50% of our patients with abdominal sepsis develop ARF, resulting in a dramatic increase in mortality. Goal of renal monitoring in sepsis is to detect ARF as early as possible and to differentiate between extrarenal and septic origin to enable immediate surgical treatment.

[Problems of blood replacement in liver transplantation]

Liver transplantation often is accompanied with massive bleeding-blood losses up to 125 I have been reported. A survey of 21 transplantations describes the management for substitution of blood components. After an initial series of 18 patients including 4 cases with blood losses exceeding 100 units of blood, an attempt was made to optimize coagulation in 5 cases with NT-values below 40% by preoperative plasmapheresis. Platelet transfusion was performed in all cases with platelet values below 120 000. These measures led to a significant reduction in blood units substituted during the last 9 transplantations.

[Pathogenic flora in the gastric juice and bronchial secretion of long-term ventilated intensive-care patients]

Nosocomial pneumonia is a major risk for long term ventilated ICU patients. The infection route may be hematogenic or via inhalation or aspiration of microorganisms. The source of aspiration is the oropharynx. This prospective study intended to study the role of the stomach as a reservoir of bacteria in ICU patients treated with cimetidine. Gastric juice and bronchial secretion from 34 patients ventilated for more than 4 days were examined bacteriologically. 72,8% of the gastric (G) and 79,1% of the bronchial aspirates (B) revealed significant bacterial growth (more than 10(4) microorganism/ml). Pseudomonas, Klebsiella, and Candida spp. were found in 56,7% (B) and 51,8% (G) of the positive cultures as an effect of selection caused by antibiotics. Organisms of intestinal origin were found in 17,8% (B) und 15,5% (G), respectively. In 32,5%, identical organisms or patterns of organisms were found in the gastric and bronchial aspirates. 7 of the 34 patients (20,6%) developed pneumonia; in 6 of these 7 cases, the same organisms could be identified at the same and/or at the last examination before developing pneumonia in gastric content and bronchial secretion. The pH-value of the sterile aspirates was lower than of the colonized aspirates (5,39 vs 5,99). During enteral nutrition, 31,4% of the aspirates were sterile, whereas during parenteral nutrition only 24,3% of the gastric aspirates were sterile. Therefore, enteral nutrition should be started as soon as possible, the pH-value should be checked frequently and should not exceed 4 in order to reduce bacterial overgrowth in the stomach. A further consequence is to use as few antibiotics as possible.

Zur Problematik des Blutersatzes bei Lebertransplantationen

Die Lebertransplantation ist der Wahleingriff mit dem höchsten Risiko einer Massivtransfusion, wobei hier Rekordwerte von über 125 1 berichtet werden. Es wird ein Überblick über das Vorgehen im eigenen Arbeitsbereich gegeben. Nach einer Serie von vier Patienten mit jeweils mehr als 100 Konserven Transfusionsmenge wurde zur präoperativen Optimierung der Gerinnung bei fünf Patienten eine Plasmapherese durchgeführt, wenn der Normotest unter 40% lag. Bei alien Patienten wurde auβerdem die Indikation zur Thrombozytengabe wesentlich groβzügiger gestellt; schon bei Werten unter 120000 wurden Konzentrate transfundiert. Dadurch lieβ sich der Blutver-brauch entscheidend senken.

[Parenteral feeding in outpatients. Indications, technic, experiences]

Home parenteral nutrition is indicated in the short bowel syndrome, chronic inflammatory bowel disease and as an adjunct to cancer therapy. For venous access the cannulation of a collateral of the subclavian vein and the central venous silastic catheter have proved helpful. Our own experience with 19 patients shows, that with careful supervision home parenteral nutrition can be performed with low risk.

Oestrogen and progesterone content of ovarian vein blood of the ewe during the oestrous cycle

Ovarian vein blood was collected by cannulating the ovarian vein of 37 ewes at various times during the oestrous cycle. Plasma progesterone and oestrogen concentrations, determined by chemical methods, showed marked cyclic variations during the cycle. Progesterone was detected at all stages of the cycle. Plasma concentrations were rising rapidly by the 4th day after the onset of oestrus and were maintained at levels greater than 100 μg./100 ml. plasma from the 8th to the 14th day of the cycle. They started to fall about 48 hr. before the onset of oestrus. Very low levels, of the order of 1 μg./100 ml. plasma, were maintained from 24 hr. before to 8–16 hr. after the onset of oestrus.

Oestradiol-17β made up almost all of the oestrogens measured. Oestrone accounted for less than one-eighth of the total oestrogens. Oestradiol first appeared on the 14th day of the cycle and its concentration rose rapidly during the immediate pre-oestrous period to reach peak levels of over 100 ng./100 ml. plasma 20–30 hr. before the onset of oestrus. They then rapidly declined and by 24 hr. after the onset had reached almost non-detectable levels.

The ovarian secretion rate of progesterone was calculated to be 3·5 mg./day at mid-cycle and the total secretion of oestradiol during the follicular phase was 4·9 μg. Blood flow through the cannula was not affected by either the stage of cycle at which blood was collected or by the structure (corpus luteum or Graafian follicle) in the ovary bled.