Ventilation Strategies During General Anesthesia for Noncardiac Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

The optimal ventilation strategy during general anesthesia is unclear. This systematic review investigated the relationship between ventilation targets or strategies (eg, positive end-expiratory pressure [PEEP], tidal volume, and recruitment maneuvers) and postoperative outcomes.

METHODS

PubMed and Embase were searched on March 8, 2021, for randomized trials investigating the effect of different respiratory targets or strategies on adults undergoing noncardiac surgery. Two investigators reviewed trials for relevance, extracted data, and assessed risk of bias. Meta-analyses were performed for relevant outcomes, and several subgroup analyses were conducted. The certainty of evidence was evaluated using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

This review included 63 trials with 65 comparisons. Risk of bias was intermediate for all trials. In the meta-analyses, lung-protective ventilation (ie, low tidal volume with PEEP) reduced the risk of combined pulmonary complications (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.28-0.49; 9 trials; 1106 patients), atelectasis (OR, 0.39; 95% CI, 0.25-0.60; 8 trials; 895 patients), and need for postoperative mechanical ventilation (OR, 0.36; 95% CI, 0.13-1.00; 5 trials; 636 patients). Recruitment maneuvers reduced the risk of atelectasis (OR, 0.44; 95% CI, 0.21-0.92; 5 trials; 328 patients). We found no clear effect of tidal volume, higher versus lower PEEP, or recruitment maneuvers on postoperative pulmonary complications when evaluated individually. For all comparisons across targets, no effect was found on mortality or hospital length of stay. No effect measure modifiers were found in subgroup analyses. The certainty of evidence was rated as very low, low, or moderate depending on the intervention and outcome.

CONCLUSIONS

Although lung-protective ventilation results in a decrease in pulmonary complications, randomized clinical trials provide only limited evidence to guide specific ventilation strategies during general anesthesia for adults undergoing noncardiac surgery.

Fraction of Inspired Oxygen During General Anesthesia for Non-Cardiac Surgery: Systematic Review and Meta-Analysis

Background

Controversy exists regarding the effects of a high versus a low intraoperative fraction of inspired oxygen (FiO₂) in adults undergoing general anesthesia. This systematic review and meta‐analysis investigated the effect of a high versus a low FiO₂ on postoperative outcomes.

Methods

PubMed and Embase were searched on March 22, 2022 for randomized clinical trials investigating the effect of different FiO₂ levels in adults undergoing general anesthesia for non‐cardiac surgery. Two investigators independently reviewed studies for relevance, extracted data, and assessed risk of bias. Meta‐analyses were performed for relevant outcomes, and potential effect measure modification was assessed in subgroup analyses and meta‐regression. The evidence certainty was evaluated using GRADE.

Results

This review included 25 original trials investigating the effect of a high (mostly 80%) versus a low (mostly 30%) FiO₂. Risk of bias was intermediate for all trials. A high FiO₂ did not result in a significant reduction in surgical site infections (OR: 0.91, 95% CI 0.81–1.02 [p = .10]). No effect was found for all other included outcomes, including mortality (OR = 1.27, 95% CI: 0.90–1.79 [p = .18]) and hospital length of stay (mean difference = 0.03 days, 95% CI −0.25 to 0.30 [p = .84). Results from subgroup analyses and meta‐regression did not identify any clear effect modifiers across outcomes. The certainty of evidence (GRADE) was rated as low for most outcomes.

Conclusions

In adults undergoing general anesthesia for non‐cardiac surgery, a high FiO₂ did not improve outcomes including surgical site infections, length of stay, or mortality. However, the certainty of the evidence was assessed as low.

Goal-directed haemodynamic therapy during general anaesthesia for noncardiac surgery: a systematic review and meta-analysis

BACKGROUND

During general anaesthesia for noncardiac surgery, there remain knowledge gaps regarding the effect of goal-directed haemodynamic therapy on patient-centred outcomes.

METHODS

Included clinical trials investigated goal-directed haemodynamic therapy during general anaesthesia in adults undergoing noncardiac surgery and reported at least one patient-centred postoperative outcome. PubMed and Embase were searched for relevant articles on March 8, 2021. Two investigators performed abstract screening, full-text review, data extraction, and bias assessment. The primary outcomes were mortality and hospital length of stay, whereas 15 postoperative complications were included based on availability. From a main pool of comparable trials, meta-analyses were performed on trials with homogenous outcome definitions. Certainty of evidence was evaluated using Grading of Recommendations, Assessment, Development, and Evaluations (GRADE).

RESULTS

The main pool consisted of 76 trials with intermediate risk of bias for most outcomes. Overall, goal-directed haemodynamic therapy might reduce mortality (odds ratio=0.84; 95% confidence interval [CI], 0.64 to 1.09) and shorten length of stay (mean difference=-0.72 days; 95% CI, -1.10 to -0.35) but with low certainty in the evidence. For both outcomes, larger effects favouring goal-directed haemodynamic therapy were seen in abdominal surgery, very high-risk surgery, and using targets based on preload variation by the respiratory cycle. However, formal tests for subgroup differences were not statistically significant. Goal-directed haemodynamic therapy decreased risk of several postoperative outcomes, but only infectious outcomes and anastomotic leakage reached moderate certainty of evidence.

CONCLUSIONS

Goal-directed haemodynamic therapy during general anaesthesia might decrease mortality, hospital length of stay, and several postoperative complications. Only infectious postoperative complications and anastomotic leakage reached moderate certainty in the evidence.

Modeling Metastatic Colonization in a Decellularized Organ Scaffold-Based Perfusion Bioreactor

Metastatic cancer spread is responsible for most cancer-related deaths. To colonize a new organ, invading cells adapt to, and remodel, the local extracellular matrix (ECM), a network of proteins and proteoglycans underpinning all tissues, and a critical regulator of homeostasis and disease. However, there is a major lack in tools to study cancer cell behavior within native 3D ECM. Here, an in-house designed bioreactor, where mouse organ ECM scaffolds are perfused and populated with cells that are challenged to colonize it, is presented. Using a specialized bioreactor chamber, it is possible to monitor cell behavior microscopically (e.g., proliferation, migration) within the organ scaffold. Cancer cells in this system recapitulate cell signaling observed in vivo and remodel complex native ECM. Moreover, the bioreactors are compatible with co-culturing cell types of different genetic origin comprising the normal and tumor microenvironment. This degree of experimental flexibility in an organ-specific and 3D context, opens new possibilities to study cell-cell and cell-ECM interplay and to model diseases in a controllable organ-specific system ex vivo.

Adenosine, Lidocaine, and Magnesium Support a High Flow, Hypotensive, Vasodilatory State With Improved Oxygen Delivery and Cerebral Protection in a Pig Model of Noncompressible Hemorrhage

BACKGROUND

Noncompressible hemorrhage is the leading cause of preventable death in military and civilian trauma. Our aim was to examine the effect of adenosine, lidocaine, and magnesium (Mg²⁺; ALM) on cardiovascular and cerebral function in a porcine hepatic hemorrhage model.

MATERIALS AND METHODS

Pigs (59.1 ± 0.34 kg) were anesthetized, instrumented, and randomly assigned into sham (n = 6), saline controls (n = 10) or ALM (n = 10) groups before laparoscopic liver resection. After 30 min, groups received 4 mL/kg 3% NaCl ± ALM bolus (Phase 1) followed 60 min later with 3 mL/kg/h 0.9% NaCl ± ALM drip (4 h; Phase 2), then transfusion. Hemodynamics, carotid artery flow, and intracranial pressure were measured continuously. Microdialysis samples were analyzed for metabolites.

RESULTS

Saline controls had 20% mortality (mean survival time: 307 ± 38 min) with no ALM deaths over 6 h. Bolus administration increased mean arterial pressure (MAP) in both groups, and drip led to further increases to 62 ± 10 mmHg in controls compared with a steady fall to 47 ± 8 mmHg in ALM group at 240 min. The lower MAP was associated with a dramatic fall in systemic vascular resistance and improved oxygen delivery. ALM drip significantly increased cardiac output and stroke volume with lower dP/dt_Min, indicating a less stiff heart. ALM drip also significantly decreased cerebral perfusion pressure, reduced cerebral oxygen consumption (28%), and reduced brain glycerol (60%), lactate (47%), and relative expression of hypoxia-inducible factor (38%) compared with saline controls.

CONCLUSIONS

ALM therapy improved cardiac function and oxygen delivery by lowering systemic vascular resistance after noncompressible hemorrhage. ALM also appeared to protect the brain at hypotensive MAPs with significantly lower cerebral perfusion pressure, lower O₂ consumption, and significantly lower cortical lactate and glycerol levels compared to saline controls.

Genetic characterization of a herd of the endangered Danish Jutland cattle

In this paper we present results from a genetic characterization of a herd of the Danish Jutland cattle breed named the Kortegaard herd (n = 135; 57 males and 78 females). The herd is genotyped on the Bovine HD BeadChip microarray with 697,548 evenly spaced SNP across the bovine genome. The aim of the study was to characterize the genetic profile of the Kortegaard herd, which has been closed for several generations, by quantifying the degree of genetic homogeneity within the herd and to compare its genetic profile to that of other cattle breeds. A total of 868 animals from the Angus, Belgian Blue, Charolais, Friesian, Hereford, Holstein, Holstein-Friesian crosses, Limousin, and Simmental breeds was used for genetic profile comparisons. The level of genetic variation within the breeds were quantified by the expected heterozygosity (H(E)), observed heterozygosity (H(O)), average minor allele frequency (MAF), the degree of polymorphism, and runs of homozygosity (ROH), which are contiguous lengths of homozygous genotypes of varying length. Interestingly, the Kortegaard herd had the lowest within-breed genetic variation (lowest H(E), H(O), and MAF), showed moderate levels of short ROH (<5 Mb), and had the highest mean long ROH (>5 Mb) compared to all the other breeds. This is possibly due to recent consanguineous matings, a strong founder effect, and a lack of gene flow from other herds and breeds. We further examined whether the observed genetic patterns in the Kortegaard herd can be used to design breeding strategies for the preservation of the genetic pool by focusing on a subset of SNP outside homozygote regions. By calculating the pairwise identical-by-state between all possible matings, we designed a breeding plan that maximized heterozygosity in the short term. The benefits and limitations of such a breeding strategy are discussed.

X-ray tomography using the full complex index of refraction

We report on x-ray tomography using the full complex index of refraction recorded with a grating-based x-ray phase-contrast setup. Combining simultaneous absorption and phase-contrast information, the distribution of the full complex index of refraction is determined and depicted in a bivariate graph. A simple multivariable threshold segmentation can be applied offering higher accuracy than with a single-variable threshold segmentation as well as new possibilities for the partial volume analysis and edge detection. It is particularly beneficial for low-contrast systems. In this paper, this concept is demonstrated by experimental results.

Molecular X-ray computed tomography of myelin in a rat brain

In this work we demonstrate the feasibility of applying small-angle X-ray scattering computed tomography (SAXS-CT) for non-invasive molecular imaging of myelin sheaths in a rat brain. Our results show that the approach yields information on several quantities, including the relative myelin concentration, its periodicity, the total thickness of the myelin sheaths, and the relative concentration of cytoskeletal neurofilaments. For example the periodicity of the myelin sheaths varied in the range from 17.0 to 18.2 nm around an average of 17.6 (±0.3) nm. We believe that imaging, i.e., spatially resolved measuring these quantities could provide general means for understanding the relation to a number of neurodegenerative diseases.

Diversity and stability of Aleutian mink disease virus during bottleneck transitions resulting from eradication in domestic mink in Denmark

Aleutian mink disease (plasmacytosis) virus (AMDV) in domestic mink (Neovison vison) has been subject to eradication in Denmark since 1976. In 2001, approximately 5% of Danish mink farms were still infected and all were located in the northern part of the peninsula of Jutland. In the present study a total of 274 Danish isolates of AMDV collected during the two seasons of 2004 and 2005 were characterized by partial sequencing of the coding region of the non-structural (NS) proteins. Older AMDV isolates from Denmark, available, were also included. The Danish isolates represent a very homogenous cluster compared with Swedish, Finnish and Dutch isolates and seem to represent a minor fraction of the genetic diversity previously found in Denmark. Stability of nucleotide deviations reveals that the purifying selection of bottlenecks imposed on the AMDV population in Denmark by the stamping out policy for more than 6 years exceeds the rate of mutation driven diversity. Among the isolates from farms in northern Jutland two distinct types could be identified and within each of them a number of sub-types which were all useful in tracking spread of infections. Infection at a farm the preceding season was a predisposing risk parameter for disease outbreak at a farm, and strain identity substantiates the suggestion that inadequate disinfection is involved in the recurrence of outbreaks. In cases of new introductions to farms it is indicated that contact including transport between farms played a most significant role.

Time-related Decrease in Diffusion Capacity in HIV-infected Patients with Impaired Immune Function

The purpose of this study was to investigate acute and time-related changes in lung function, i.e. forced expiratory volume in 1 second (FEV1), vital capacity (VC) and transfer factor (KCO) in HIV-infected patients with CD4 cell counts less than 400 x 10(6)/l. 66 males with no history of HIV-related pulmonary symptoms participated in a prospective lung function study for 9 months with 3-month intervals between examinations. 15/66 patients (23%) developed acute pulmonary symptoms, i.e. dyspnea (n = 12), cough (n = 13), fever greater than 38 degrees C (n = 13) and interstitial infiltrates on the X-ray (n = 9). Among the 51 asymptomatic patients, a significant time-related decrease in KCO (median decrease of 7%) was found, whereas no significant change in FEV1 or VC was observed during the study. Baseline KCO, i.e. KCO at entry, was found to be significantly higher in the asymptomatic patients (102% predicted (pred.) than in those patients who developed pneumonia (88% pred.). Development of pulmonary symptoms was both followed by a significant decrease in KCO (median decrease 17%), FEV1 and VC. We therefore conclude that HIV-infected patients with impaired immune function have in the absence of pulmonary symptoms a decrease in KCO. In case of pneumonia an acute decrease in both KCO, FEV1 and VC occurs.

Dynamics in shear flow studied by X-ray Photon Correlation Spectroscopy

X-ray Photon Correlation Spectroscopy was used to measure the diffusive dynamics of colloidal particles in a shear flow. The results presented here show how the intensity autocorrelation functions measure both the diffusive dynamics of the particles and their flow-induced, convective motion. However, in the limit of low flow/shear rates, it is possible to obtain the diffusive component of the dynamics, which makes the method suitable for the study of the dynamical properties of a large class of complex soft-matter and biological fluids. An important benefit of this experimental strategy over more traditional X-ray methods is the minimization of X-ray-induced beam damage. While the method can be applied also for photon correlation spectroscopy in the visible domain, our analysis shows that the experimental conditions under which it is possible to measure the diffusive dynamics are easier to achieve at higher q values (with X-rays).

Global gene expression analysis in fetal mouse ovaries with and without meiosis and comparison of selected genes with meiosis in the testis

In order to identify novel genes involved in early meiosis and early ovarian development in the mouse, we used microarray technology to compare transcriptional activity in ovaries without meiotic germ cells at embryonic age 11.5 (E11.5) and E13.5 ovaries with meiosis. Overall, 182 genes were differentially expressed; 134 were known genes and 48 were functionally uncharacterized. A comparison of our data with the literature associated, for the first time, at least eight of the known genes with female meiosis/germ cell differentiation (Aldh1a1, C2pa, Tex12, Stk31, Lig3, Id4, Recql, Piwil2). These genes had previously only been described in spermatogenesis. The microarray also detected an abundance of vesicle-related genes of which four were upregulated (Syngr2, Stxbp1, Ric-8, SytIX) and one (Myo1c) was downregulated in E13.5 ovaries. Detailed analysis showed that the temporal expression of SytIX also coincided with the first meiotic wave in the pubertal testis. This is the first time that SytIX has been reported in non-neuronal tissue. Finally, we examined the expression of one of the uncharacterized genes and found it to be gonad-specific in adulthood. We named this novel transcript "Gonad-expressed transcript 1" (Get-1). In situ hybridization showed that Get-1 was expressed in meiotic germ cells in both fetal ovaries and mature testis. Get-1 is therefore a novel gene in both male and female meiosis.

Transcriptome analysis of FSH and FSH variant stimulation in granulosa cells from IVM patients reveals novel regulated genes

FSH is crucial for oocyte maturation and fertility and is the main component in infertility treatment in assisted reproduction. The granulosa cells expressing the FSH receptor interact with the oocyte and provide nourishing substrates controlling the oocyte maturation. Thus, transcriptome analysis of granulosa cells stimulated by FSH is of major importance in understanding the communication between oocytes and granulosa cells. In this study, gene expression profiles were assessed in human granulosa cells from normal cycling in vitro maturation (IVM) patients using oligonucleotide gene chips. Granulosa cells were stimulated for 2 h with either FSH or a previously generated glycosylated FSH variant (FSH1208) that exhibited increased in vivo activity because of prolonged half-life. The analysis identified 74 significantly FSH/FSH1208 regulated genes. Amongst these were well known FSH regulated genes as well as genes not previously described to be important in the FSH signalling pathway. These novel FSH regulated genes include transcription factors [cAMP responsive element modulator (CREM)/inducible cAMP early repressors (ICER), GATA 6, ZFN 361, Bcl11a, CITED1 and TCF 8] and other regulatory proteins and enzymes (IGF-BP3, syntaxin and PCK1) possibly important for oocyte/granulosa cell interaction and function. Array data were validated for 13 genes by northern blots or RT-PCR. Furthermore, no significant differences in gene regulation were detected between the two FSH analogs. This work uncovers novel data important for understanding the folliculogenesis. Furthermore, the results suggest that FSH1208 has a gene expression profile like FSH and thus, in the light of known prolonged in vivo activity, might be a candidate for improved infertility treatment.

Lactic acidosis in the rectal lumen of patients with septic shock measured by luminal equilibrium dialysis

BACKGROUND

Gut ischaemia may contribute to morbidity in sepsis, but little is known about the metabolic state of the gut mucosa in such patients.

METHODS

Nine patients with abdominal septic shock treated with norepinephrine, and ten healthy subjects, were subjected to equilibrium dialysis with a rectal balloon. pH, PCO(2) and concentrations of L-lactate were measured by auto-analyser.

RESULTS

In rectal dialysis fluid from patients with septic shock, acidosis was present (pH 7.23, 95% CI 7.11-7.36) and concentrations of L-lactate were approximately five times greater than controls (2.5-5.8 vs 0.5-1.2 mmol litre(-1)). The lactate concentration was related to the dose of norepinephrine (P<0.001). In contrast, values of dialysate PCO(2) did not differ significantly between patients and controls (6.4-11.0 vs 8.9-13.8 kPa).

CONCLUSIONS

The results suggest that, either lactic acidosis in rectal mucosa is related to shock severity, or that norepinephrine causes mucosal ischaemia. In any case, metabolic dysfunction is present in the rectal mucosa in patients with abdominal septic shock treated with norepinephrine.

Variations in the severity of phocid herpesvirus type 1 infections with age in grey seals and harbour seals

The data recorded during an outbreak of phocid herpesvirus type 1 infection among 19 harbour seals and 29 grey seals being nursed in a seal rehabilitation centre in The Netherlands in 1998 were used, together with data from similar outbreaks in previous years, to compare the clinical signs observed in the two species at different ages. The severity of the disease was inversely correlated with age in the harbour seals, and the infected harbour seals generally developed more severe clinical signs than the infected grey seals.

The DECD box putative ATPase Sub2p is an early mRNA export factor

Nuclear mRNA metabolism relies on the interplay between transcription, processing, and nuclear export. RNA polymerase II transcripts experience major rearrangements within the nucleus, which include alterations in the structure of the mRNA precursors as well as the addition and perhaps even removal of proteins prior to transport across the nuclear membrane. Such mRNP-remodeling steps are thought to require the activity of RNA helicases/ATPases. One such protein, the DECD box RNA-dependent ATPase Sub2p/UAP56, is involved in both early and late steps of spliceosome assembly. Here, we report a more general function of Saccharomyces cerevisiae Sub2p in mRNA nuclear export. We observe a rapid and dramatic nuclear accumulation of poly(A)(+) RNA in strains carrying mutant alleles of sub2. Strikingly, an intronless transcript, HSP104, also accumulates in nuclei, suggesting that Sub2p function is not restricted to splicing events. The HSP104 transcripts are localized in a single nuclear focus that is suggested to be at or near their site of transcription. Intriguingly, Sub2p shows strong genetic and functional interactions with the RNA polymerase II-associated DNA/DNA:RNA helicase Rad3p as well as the nuclear RNA exosome component Rrp6p, which was independently implicated in the retention of mRNAs at transcription sites. Taken together, our data suggest that Sub2p functions at an early step in the mRNA export process.

Quality control of mRNA 3'-end processing is linked to the nuclear exosome

An emerging theme in messenger RNA metabolism is the coupling of nuclear pre-mRNA processing events, which contributes to mRNA quality control. Most eukaryotic mRNAs acquire a poly(A) tail during 3'-end processing within the nucleus, and this is coupled to efficient export of mRNAs to the cytoplasm. In the yeast Saccharomyces cerevisiae, a common consequence of defective nuclear export of mRNA is the hyperadenylation of nascent transcripts, which are sequestered at or near their sites of transcription. This implies that polyadenylation and nuclear export are coupled in a step that involves the release of mRNA from transcription site foci. Here we demonstrate that transcripts which fail to acquire a poly(A) tail are also retained at or near transcription sites. Surprisingly, this retention mechanism requires the protein Rrp6p and the nuclear exosome, a large complex of exonucleolytic enzymes. In exosome mutants, hypo- as well as hyperadenylated mRNAs are released and translated. These observations suggest that the exosome contributes to a checkpoint that monitors proper 3'-end formation of mRNA.

Long-term results after cemented revision of the femoral component in total hip arthroplasty

The need for revision total hip arthroplasty has been increasing. The early results have been poor, and different revision techniques have been introduced. We report our results of 84 consecutive cemented first-time revisions of femoral components performed from 1981 through 1988 using a long-stem revision component. The average time to follow-up was 11.4 years (range, 7.9-15.0 years). Patients with 47 revisions had died; 2 of these had been rerevised. Two additional patients were lost to follow-up for other reasons. Of the living patients, 12 had been rerevised, leaving 23 patients (23 hips) for complete follow-up evaluation, including clinical and radiographic assessment. Of 23 patients, 15 reported no pain, 4 had only slight pain, and 4 had more severe pain. In 4 cases, there were definite radiographic signs of loosening of the femoral component. Kaplan-Meier survivorship analysis showed an overall 10-year survival of the femoral component of 77.9%. Using rerevision because of aseptic loosening or definite radiographic loosening as endpoint, the 10-year survival was 80.7%. Simple recementation is well indicated in elderly patients with only minor bone loss.

A block to mRNA nuclear export in S. cerevisiae leads to hyperadenylation of transcripts that accumulate at the site of transcription

Several factors contribute to nuclear mRNA export in Saccharomyces cerevisiae, including Mex67p, Mtr2p, Gle1p, Nup159p, Dbp5p, and Rip1p. Strains carrying mutations in these factors show rapid and dramatic nuclear accumulation of poly(A)(+) RNA. We have characterized two heat shock mRNAs, SSA4 and HSP104, in these mutant backgrounds; each transcript concentrates in a single intranuclear focus. Evidence suggests that it coincides with the site of transcription. Interestingly, all detectable SSA4 transcripts have undergone 3'-end formation, indicating that RNAs in the foci are no longer nascent. Poly(A) tails of the transcripts are also dramatically longer in all of these export mutants. Based on all of the data, we suggest that very early mRNA maturation events determine transcript export competence.

Identification of novel Saccharomyces cerevisiae proteins with nuclear export activity: cell cycle-regulated transcription factor ace2p shows cell cycle-independent nucleocytoplasmic shuttling

Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the NES receptor CRM1/Crm1p. We have carried out a yeast two-hybrid screen with Crm1p as a bait. The Crm1p-interacting clones were subscreened for nuclear export activity in a visual assay utilizing the Crm1p-inhibitor leptomycin B (LMB). This approach identified three Saccharomyces cerevisiae proteins not previously known to have nuclear export activity. These proteins are the 5' RNA triphosphatase Ctl1p, the cell cycle-regulated transcription factor Ace2p, and a protein encoded by the previously uncharacterized open reading frame YDR499W. Mutagenesis analysis show that YDR499Wp contains an NES that conforms to the consensus sequence for leucine-rich NESs. Mutagenesis of Ctl1p and Ace2p were unable to identify specific NES residues. However, a 29-amino-acid region of Ace2p, rich in hydrophobic residues, contains nuclear export activity. Ace2p accumulates in the nucleus at the end of mitosis and activates early-G(1)-specific genes. We now provide evidence that Ace2p is nuclear not only in late M-early G(1) but also during other stages of the cell cycle. This feature of Ace2p localization explains its ability to activate genes such as CUP1, which are not expressed in a cell cycle-dependent manner.

[Emergency room patients and alcohol consumption]

To investigate the consumption of alcohol among emergency room patients, we included 395 patients above 18 years old entering the emergency room during a period of ten days. The patients completed a questionnaire about alcohol consumption, smoking habits and medication. In our investigation 56% of the men and 25% of the women had a daily consumption above the limits recommended by the Ministry of Health (three drinks daily for men and two for women), while 41% men and 14% women consumed at least five drinks daily or 35 per week. Trauma seen in male patients with high alcohol consumption was characterised by excessive damage to the head, trauma of the lower limb and blows from an object, person or an animal. The alcoholic women were characterised by excessive chemical injuries, incisions and stab wounds, and trauma of the upper limb. In conclusion a surprisingly large amount of emergency room patients can be defined as alcohol abusers and drinking is found to be associated with excessive damage.

The specificity of the CRM1-Rev nuclear export signal interaction is mediated by RanGTP

Nuclear export of intron-containing human immunodeficiency virus type 1 (HIV-1) RNA is mediated by the viral Rev protein that contains both an RNA binding domain specific for the viral Rev response element (RRE) and a nuclear export signal (NES). The cellular CRM1 (Exportin1) protein functions as a nuclear export receptor for proteins carrying a Rev-like NES in a process that also requires the GTP bound form of the Ran GTPase. Using purified recombinant factors, we show by co-precipitation, gel mobility shift and protein footprinting assays that full-length Rev protein interacts directly with CRM1 in vitro independently of both the integrity of the characteristic leucine residues of the NES and the presence of the cytotoxin leptomycin B (LMB). Addition of RanGTP induces the formation of an RRE-Rev-CRM1-RanGTP complex that is sensitive to LMB, NES mutations, and Ran being charged with GTP. Within this complex, CRM1 is readily cross-linked to Cys89 near the NES of Rev. By protein footprinting, we demonstrate that the NES of Rev and two regions in CRM1 become inaccessible to endoproteinases upon binding suggesting that these regions are involved in protein-protein interactions. Our data are consistent with a model in which CRM1 is the nuclear export receptor for the Rev-RRE ribonucleoprotein complex and that RanGTP binds to a preformed Rev-CRM1 complex and specifies a functional interaction with the NES.

HIV-1 rev nuclear export signal binding peptides isolated by phage display

The human immunodeficiency virus type 1 (HIV-1) Rev protein is absolutely essential in the viral replication cycle, where it induces the production of viral structural proteins. Rev functions in part by inducing the nuclear export of incompletely spliced mRNA species specified by the presence of an RNA element, the Rev response element (RRE). Several proteins implicated in RNA processing and nucleo-cytoplasmic transport have been shown to interact with Rev, however, their exact roles remain unknown. To map potential protein recognition sites within the Rev structure, we have screened a phage library, displaying random 15-mer peptides, and isolated clones exhibiting similar sequences that specifically interact with Rev. The binding sites on Rev of the corresponding synthetic peptides were characterised by protein footprinting, involving partial proteolysis of radioactively end-labelled Rev protein. Two of the peptides produced a significant footprint within the nuclear export signal of Rev, raising the possibility that they mimic the binding of cellular protein factors implicated in nuclear export.

Probing the structure of HIV-1 Rev by protein footprinting of multiple monoclonal antibody-binding sites

Human immunodeficiency virus type 1 (HIV-1) Rev is a small RNA-binding protein which is essential for viral replication. To investigate the structure of Rev we have mapped the binding sites of a panel of monoclonal antibodies (mAb) by protein footprinting and identified a mAb protecting amino acids within both the N- and C-terminal parts of Rev. Our mapping results support a previously proposed structure (Auer et al., Biochemistry, 33 (1994) 2988-2996) predicting that a helix-loop-helix motif in Rev brings the termini of the protein into proximity. Furthermore, we demonstrate that the binding sites mapped by protein footprinting are in agreement with conventional epitope mapping results and that this technique provides an advantageous strategy for mapping discontinuous sites.

In vitro interaction between human immunodeficiency virus type 1 Rev protein and splicing factor ASF/SF2-associated protein, p32

Continuous replication of human immunodeficiency virus type 1 requires the expression of the regulatory protein Rev, which binds to the Rev response element (RRE) and up-regulates the cytoplasmic appearance of singly spliced and unspliced mRNA species. It has been demonstrated that the murine protein YL2 interacts with Rev in vivo and modulates the activity of Rev (Luo, Y., Yu, H., and Peterlin, B. M. (1994) J. Virol. 68, 3850-3856). Here we show that the YL2 human homologue, the p32 protein, which co-purifies with alternative splicing factor ASF/SF2, interacts directly with the basic domain of Rev in vitro and that the Rev-p32 complex is resistant to high concentrations of salt or nonionic detergent. Protein footprinting data suggest that Rev interacts specifically with amino acids within the 196-208 region of p32. An analysis of the ternary complex, formed among p32, Rev, and RRE RNA, shows that Rev can bridge the association of p32 and RRE. Furthermore, we demonstrate that exogenously added p32 specifically relieves the inhibition of splicing in vitro exerted by the basic domain of Rev. Our data are consistent with a model in which p32 functions as a link between Rev and the cellular splicing apparatus.

Tools for the production and purification of full-length, N- or C-terminal 32P-labeled protein, applied to HIV-1 Gag and Rev

We have constructed two new vectors for the production of foreign proteins in Escherichia coli. The vectors, pGEX-GTH and pET-HTG, produce protein fused to glutathione S-transferase (GST) at the N- and C-termini, respectively, allowing one-step purification on glutathione-Sepharose. Furthermore, they carry the recognition sequence (RRASV) for the catalytic subunit of cAMP-dependent heart muscle kinase (HMK) at the terminus distal to the GST tag, enabling specific 32P labeling in vitro. By positioning the GST and HMK sequences at opposite ends of the introduced gene, only full-length fusion protein becomes radiolabeled after purification. Avoiding the labeling of shorter fusion protein species, often observed in bacterial expression of foreign genes, is particularly important for a number of different purposes, including protein mobility shift analysis and protein footprinting technology.

Exercise-induced gastric mucosal acidosis

Gastric acidosis as assessed by tonometry was applied to evaluate changes in splanchnic blood flow during exercise. In six healthy male oarsmen, we determined gastric acidosis in response to 30 min of maximal ergometer rowing. The gastric mucosa carbon dioxide tension was determined by equilibration of isotonic saline to the tonometer. Arterial bicarbonate (HCO3-), pH, arterial oxygen tension (PaO2), and saturation (SaO2) were obtained simultaneously, while pH (pHi) of the gastric mucosa was calculated using the Henderson-Hasselbach equation. During rowing PaO2 and SaO2 decreased to values of 73.7 mm Hg and 95.5%, respectively (P < 0.05). However, during the last minute of rowing the values were normalized with a hyperventilation reducing PaCO2 to 27.1 mm Hg (P < 0.05). Rowing decreased HCO3- from 25.8 (21.4-28.5) to 14.1 (11.6-17.4) mmol l-1, while the gastric carbon dioxide tension increased from 36.8 (24.1-63.9) to 61.7 (48.9-82.0) mm Hg (P < 0.05). Accordingly, pHi decreased from 7.25 (7.04-7.48) to 6.79 (6.67-6.85) (P < 0.05). Arterial pH also decreased (from 7.42 (7.41-7.44) to 7.29 (7.26-7.33) (P < 0.05)), with the enlarged difference between pH and pHi suggesting marked splanchnic hypoperfusion during rowing.

Intermolecular binding sites of human immunodeficiency virus type 1 Rev protein determined by protein footprinting

Human immunodeficiency virus encodes the regulatory protein Rev, which is required for expression of viral structural proteins. It binds to an RNA element (RRE) in the viral transcript and up-regulates the cytoplasmic appearance of unspliced and singly spliced viral mRNA. We have studied the structure of Rev alone and complexed with the RRE and two monoclonal antibodies, using a protein footprinting approach. The method involves radioactive labeling at the C-terminal end of Rev fusion protein followed by limited proteolysis under native conditions, using 10 different proteinases. Rev protein was mainly cleaved within the basic domain and in the C-terminal part. The periodicity of the proteolytic cleavages within the basic domain strongly suggests that it forms an alpha-helical structure with one side facing the solvent. In the presence of RRE, these cleavages became significantly reduced. In addition, strong protection was observed at position 66 outside the basic domain. As a control for the specificity of the footprinting reaction, we confirmed the position of the epitopes for two monoclonal antibodies. This protein footprinting methodology is generally applicable to other proteins for which terminal modifications are acceptable, and provides a useful tool for mapping structure, substrate binding, and conformational changes.

[Nitrogen oxide inhalation in acute pulmonary failure]

Two cases of adult respiratory distress syndrome (ARDS) treated successfully with nitric oxide (NO) inhalation are described. One patient had severe sepsis and the other had trauma induced ARDS. The slow entry criteria for extracorporeal membrane oxygenation (ECMO) was fulfilled in both cases. NO inhalation substantially improved oxygenation, reduced pulmonary arterial pressure and peak inspiratory pressure. Treatment with NO inhalation was without side effects and easy to administer through the ventilator. Both patients survived without sequelae. We suggest that inhalation with NO should be tried before ECMO treatment is considered in severe ARDS.

[Translocation and multiple organ failure]

A review of bacterial translocation and multiple organ failure (MOF) is presented. Splanchnic ischaemia plays a central role in the development of MOF, but the exact mechanism of translocation is unclear. The concentration of endotoxins and bacteria in the gut is high. The critically ill patient is often treated with antibiotics with a broad antibacterial spectrum and overgrowth of Gram negative bacteria will take place in the gut favouring the translocation phenomenon. The regime of selective gut decontamination is discussed. Regional and systemic oxygen kinetics together with metabolic markers are important in detecting splanchnic ischaemia. Hepatic vein catheterisation and gastric mucosa pHi are discussed. The regional inflammation in the gut is often initiated by endotoxins, which stimulate the cytokines IL-1, IL-6 and TNF. Another important factor that can accentuate inflammation of the gut is reperfusion injury. A proposal for treatment of splanchnic ischaemia and translocation is discussed i.e.: optimizing central haemodynamic parameters, optimizing the regional microcirculation, treatment with antibodies to endotoxins, gut decontamination and early enteral nutrition. When splanchnic hypoperfusion is detected it cannot be ignored. It may be possible to correct the hypoperfusion with early gastrointestinal resuscitation and to thereby reduce the duration and mortality of MOF. The above mentioned suggestions are all very demanding of resources, but have to be considered in gut directed therapy.

Tuberculous meningitis. 23 cases from a 12-year period (1976-1987)

Twenty-three patients with tuberculous meningitis were reviewed to see whether clinical features or initial laboratory findings could discriminate between these patients and other patients with bacterial meningitis. Nineteen patients were Danes and four immigrants. Preexisting diseases were found in eight cases. Duration of symptoms could be related to neurological sequelae, but not to death. The initial clinical picture was indistinguishable from meningitis of other causes. Microscopy of the cerebrospinal fluid (CSF) was negative in all but two cases, where acid fast bacilli were found. CSF cytology and biochemistry could not discriminate from other causes bacteria of meningitis although CSF/blood glucose ratio in 56% was below 0.3. One of the most important pieces of information in establishing an early diagnosis in tuberculous meningitis is the anamnestic information, and therapy often has to be started without knowing the microbiological data.

[Total intravenous anesthesia using ketamine and midazolam. A simple technic]

Forty unpremedicated patients undergoing minor gynecological surgery were anesthetized with 1 mg ketamine and 0.1 mg midazolam per kg bodyweight, if necessary supplemented later with half the initial dose. All patients continued to breathe room air spontaneously with no ventilatory support. There were no incidents of airway obstruction and only 1 case of troublesome airway secretions. The arterial blood gas sample did not show any sign of respiratory depression, but in 11 cases paO2 was lower than normal, though acceptable. The median emergence time was 6 min. The side effects of ketamine were well controlled by midazolam, and patient acceptance of the technique was high. We consider that the technique may be suitable for short procedures under primitive conditions, for example after mass casualties, and that it can, if necessary, be applied by specially trained paramedics.

Prevention of Pneumocystis carinii pneumonia relapse by aerosolised pentamidine, 60 mg biweekly, using an Acorn System 22 nebuliser

The effectiveness of biweekly administration of 60 mg aerosolised pentamidine (AP) as secondary prophylaxis against relapse of Pneumocystis carinii pneumonia (PCP) was investigated in 45 male AIDS patients. The nebuliser used was an Acorn System 22. In total the patients received AP for a mean period of 13.8 months (3.4-28.8). Six episodes of recurrent PCP were recorded. Relapse per full year of treatment on AP was 12%.

Ondine's curse in listeria monocytogenes brain stem encephalitis

A case of necrotizing brain stem encephalitis due to listeria monocytogenes is described in a 48-year-old man who had brain stem encephalitis of complicated course and with selective destruction of the vasomotoric and respiratory centers. He developed that very rare Ondine's curse syndrome, being only able to breathe when awake. The literature on Ondine's curse and brain stem encephalitis due to LM is reviewed. Brain stem encephalitis has a mortality near 100%. The only treatment for Ondine's curse is lifelong artificial ventilation.

Listeria monocytogenes meningitis in adults. Sixteen consecutive cases 1973-1982

16 adult patients with Listeria monocytogenes meningitis were reviewed to see whether clinical features or initial laboratory findings could discriminate between these patients and patients with purulent meningitis of other causes. Six patients suffered from known predisposing diseases and 4 were alcoholics. The initial clinical picture was indistinguishable from meningitis of other causes. Microscopy of cerebrospinal fluid (CSF) was negative in all cases but 2 where gram-positive rods were seen. CSF cytology and biochemistry could not discriminate from other causes of purulent meningitis although a low leucocyte content and a low percentage of neutrophils were often present. All L. monocytogenes strains isolated were sensitive to ampicillin and aminoglycosides whereas susceptibility to other antibiotics was low or varying. In adult patients suffering from purulent meningitis initial therapy should include ampicillin until an etiological diagnosis is established. The same is true in some cases of febrile encephalopathy with low content of neutrophils in CSF, especially when the glucose content is low.