Proteogenomic Data Integration Reveals CXCL10 as a Potentially Downstream Causal Mediator for IL-6 Signaling on Atherosclerosis

BACKGROUND

Genetic and experimental studies support a causal involvement of IL-6 (interleukin-6) signaling in atheroprogression. Although trials targeting IL-6 signaling are underway, any benefits must be balanced against an impaired host immune response. Dissecting the mechanisms that mediate the effects of IL-6 signaling on atherosclerosis could offer insights about novel drug targets with more specific effects.

METHODS

Leveraging data from 522 681 individuals, we constructed a genetic instrument of 26 variants in the gene encoding the IL-6R (IL-6 receptor) that proxied for pharmacological IL-6R inhibition. Using Mendelian randomization, we assessed its effects on 3281 plasma proteins quantified with an aptamer-based assay in the INTERVAL cohort (n=3301). Using mediation Mendelian randomization, we explored proteomic mediators of the effects of genetically proxied IL-6 signaling on coronary artery disease, large artery atherosclerotic stroke, and peripheral artery disease. For significant mediators, we tested associations of their circulating levels with incident cardiovascular events in a population-based study (n=1704) and explored the histological, transcriptomic, and cellular phenotypes correlated with their expression levels in samples from human atherosclerotic lesions.

RESULTS

We found significant effects of genetically proxied IL-6 signaling on 70 circulating proteins involved in cytokine production/regulation and immune cell recruitment/differentiation, which correlated with the proteomic effects of pharmacological IL-6R inhibition in a clinical trial. Among the 70 significant proteins, genetically proxied circulating levels of CXCL10 (C-X-C motif chemokine ligand 10) were associated with risk of coronary artery disease, large artery atherosclerotic stroke, and peripheral artery disease, with up to 67% of the effects of genetically downregulated IL-6 signaling on these end points mediated by decreases in CXCL10. Higher midlife circulating CXCL10 levels were associated with a larger number of cardiovascular events over 20 years, whereas higher CXCL10 expression in human atherosclerotic lesions correlated with a larger lipid core and a transcriptomic profile reflecting immune cell infiltration, adaptive immune system activation, and cytokine signaling.

CONCLUSIONS

Integrating multiomics data, we found a proteomic signature of IL-6 signaling activation and mediators of its effects on cardiovascular disease. Our analyses suggest the interferon-γ-inducible chemokine CXCL10 to be a potentially causal mediator for atherosclerosis in 3 vascular compartments and, as such, could serve as a promising drug target for atheroprotection.

Proteogenomic integration reveals CXCL10 as a potentially downstream causal mediator for IL-6 signaling on atherosclerosis

Background

Genetic and experimental studies support a causal involvement of interleukin-6 (IL-6) signaling in atheroprogression. While trials targeting IL-6 signaling are underway, any benefits must be balanced against an impaired host immune response. Dissecting the mechanisms that mediate the effects of IL-6 signaling on atherosclerosis could offer insights about novel drug targets with more specific effects.

Methods

Leveraging data from 522,681 individuals, we constructed a genetic instrument of 26 variants in the gene encoding the IL-6 receptor (IL-6R) that proxied for pharmacological IL-6R inhibition. Using Mendelian randomization (MR), we assessed its effects on 3,281 plasma proteins quantified with an aptamer-based assay in the INTERVAL cohort (n=3,301). Using mediation MR, we explored proteomic mediators of the effects of genetically proxied IL-6 signaling on coronary artery disease (CAD), large artery atherosclerotic stroke (LAAS), and peripheral artery disease (PAD). For significant mediators, we tested associations of their circulating levels with incident cardiovascular events in a population-based study (n=1,704) and explored the histological, transcriptomic, and cellular phenotypes correlated with their expression levels in samples from human atherosclerotic lesions.

Results

We found significant effects of genetically proxied IL-6 signaling on 70 circulating proteins involved in cytokine production/regulation and immune cell recruitment/differentiation, which correlated with the proteomic effects of pharmacological IL-6R inhibition in a clinical trial. Among the 70 significant proteins, genetically proxied circulating levels of CXCL10 were associated with risk of CAD, LAAS, and PAD with up to 67% of the effects of genetically downregulated IL-6 signaling on these endpoints mediated by decreases in CXCL10. Higher midlife circulating CXCL10 levels were associated with a larger number of cardiovascular events over 20 years, whereas higher CXCL10 expression in human atherosclerotic lesions correlated with a larger lipid core and a transcriptomic profile reflecting immune cell infiltration, adaptive immune system activation, and cytokine signaling.

Conclusions

Integrating multiomics data, we found a proteomic signature of IL-6 signaling activation and mediators of its effects on cardiovascular disease. Our analyses suggest the interferon-γ-inducible chemokine CXCL10 to be a potentially causal mediator for atherosclerosis in three vascular compartments and as such could serve as a promising drug target for atheroprotection.

Digital technology and patient and public involvement (PPI) in routine care and clinical research-A pilot study

BACKGROUND

Patient and public involvement (PPI) has growing impact on the design of clinical care and research studies. There remains underreporting of formal PPI events including views related to using digital tools. This study aimed to assess the feasibility of hosting a hybrid PPI event to gather views on the use of digital tools in clinical care and research.

METHODS

A PPI focus day was held following local procedures and published recommendations related to advertisement, communication and delivery. Two exemplar projects were used as the basis for discussions and qualitative and quantitative data was collected.

RESULTS

32 individuals expressed interest in the PPI day and 9 were selected to attend. 3 participated in person and 6 via an online video-calling platform. Selected written and verbal feedback was collected on two digitally themed projects and on the event itself. The overall quality and interactivity for the event was rated as 4/5 for those who attended in person and 4.5/5 and 4.8/5 respectively, for those who attended remotely.

CONCLUSIONS

A hybrid PPI event is feasible and offers a flexible format to capture the views of patients. The overall enthusiasm for digital tools amongst patients in routine care and clinical research is high, though further work and standardised, systematic reporting of PPI events is required.

Aortic thrombosis in COVID-19

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Thrombosis associated with COVID-19 can occur at diverse sites.

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Arterial as well as venous thrombosis can complicate COVID-19.

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Thromboprophylaxis is advised for COVID-19 patients with thrombosis risk factors.

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More evidence is needed to guide specific thromboprophylaxis strategies in COVID-19.

Background

Venous thrombo-embolism is now well-recognised as a common complication of severe COVID-19 disease. Arterial thrombosis has been less well recognised, although it is increasingly reported, mostly in the context of myocardial infarction and stroke.

Case report

A 63-year-old man developed a pale, cold foot with an absent dorsalis pedis pulse 7 days into his admission with COVID-19. A CT angiogram demonstrated a large thrombus in the lower thoracic aorta, which had not been present on CT pulmonary angiogram the preceding week, along with occlusion of both popliteal arteries. He was managed with therapeutic dose of low molecular weight heparin (LMWH) for 6 weeks.

Results

This case adds to the growing list of potential sites and consequences of thrombosis in COVID-19.

Conclusion

This case underscores the urgent need for pathophysiological studies and clinical trials to target treatments and guidelines for thromboprophylaxis in COVID-19.

Novel Insights Into the Effects of Interleukin 6 Antagonism in Non-ST-Segment-Elevation Myocardial Infarction Employing the SOMAscan Proteomics Platform

Background

Interleukin 6 concentration is associated with myocardial injury, heart failure, and mortality after myocardial infarction. In the Norwegian tocilizumab non–ST‐segment–elevation myocardial infarction trial, the first randomized trial of interleukin 6 blockade in myocardial infarction, concentration of both C‐reactive protein and troponin T were reduced in the active treatment arm. In this follow‐up study, an aptamer‐based proteomic approach was employed to discover additional plasma proteins modulated by tocilizumab treatment to gain novel insights into the effects of this therapeutic approach.

Methods and Results

Plasma from percutaneous coronary intervention–treated patients, 24 in the active intervention and 24 in the placebo‐control arm, drawn 48 hours postrandomization were randomly selected for analysis with the SOMAscan assay. Employing slow off‐rate aptamers, the relative abundance of 1074 circulating proteins was measured. Proteins identified as being significantly different between groups were subsequently measured by enzyme immunoassay in the whole trial cohort (117 patients) at all time points (days 1–3 [7 time points] and 3 and 6 months). Five proteins identified by the SOMAscan assay, and subsequently confirmed by enzyme immunoassay, were significantly altered by tocilizumab administration. The acute‐phase proteins lipopolysaccharide‐binding protein, hepcidin, and insulin‐like growth factor‐binding protein 4 were all reduced during the hospitalization phase, as was the monocyte chemoattractant C‐C motif chemokine ligand 23. Proteinase 3, released primarily from neutrophils, was significantly elevated.

Conclusions

Employing the SOMAscan aptamer‐based proteomics platform, 5 proteins were newly identified that are modulated by interleukin 6 antagonism and may mediate the therapeutic effects of tocilizumab in non–ST‐segment–elevation myocardial infarction.

Pro-resolving mediators promote resolution in a human skin model of UV-killed Escherichia coli-driven acute inflammation

While the treatment of inflammatory disorders is generally based on inhibiting factors that drive onset of inflammation, these therapies can compromise healing (NSAIDs) or dampen immunity against infections (biologics). In search of new antiinflammatories, efforts have focused on harnessing endogenous pathways that drive resolution of inflammation for therapeutic gain. Identification of specialized pro-resolving mediators (SPMs) (lipoxins, resolvins, protectins, maresins) as effector molecules of resolution has shown promise in this regard. However, their action on inflammatory resolution in humans is unknown. Here, we demonstrate using a model of UV-killed Escherichia coli–triggered skin inflammation that SPMs are biosynthesized at the local site at the start of resolution, coinciding with the expression of receptors that transduce their actions. These include receptors for lipoxin A₄ (ALX/FPR2), resolvin E1 (ChemR23), resolvin D2 (GPR18), and resolvin D1 (GPR32) that were differentially expressed on the endothelium and infiltrating leukocytes. Administering SPMs into the inflamed site 4 hours after bacterial injection caused a reduction in PMN numbers over the ensuing 6 hours, the phase of active resolution in this model. These results indicate that in humans, the appearance of SPMs and their receptors is associated with the beginning of inflammatory resolution and that their therapeutic supplementation enhanced the resolution response.

In humans, the appearance of specialized pro-resolving lipid mediators and their receptors is associated with the start of inflammatory resolution.

Potent Anti-Inflammatory and Pro-Resolving Effects of Anabasum in a Human Model of Self-Resolving Acute Inflammation

Anabasum is a synthetic analog of Δ⁸‐tetrahydrocannabinol (THC)‐11‐oic acid that in preclinical models of experimental inflammation exerts potent anti‐inflammatory actions with minimal central nervous system (CNS) cannabimimetic activity. Here we used a novel model of acute inflammation driven by i.d. UV‐killed E. coli in healthy humans and found that anabasum (5 mg) exerted a potent anti‐inflammatory effect equivalent to that of prednisolone in terms of inhibiting neutrophil infiltration, the hallmark of acute inflammation. These effects arose from the inhibition of the neutrophil chemoattractant LTB₄, while the inhibition of antiphagocytic prostanoids (PGE₂, TxB₂, and PGF₂α) resulted in enhanced clearance of inflammatory stimulus from the injected site. Anabasum at the higher dose of 20 mg possessed the additional properties of triggering the biosynthesis of specialized pro‐resolving lipid mediators including LXA₄, LXB₄, RvD1, and RvD3. Collectively, we demonstrate for the first time a striking anti‐inflammatory and pro‐resolution effects of a synthetic analog of THC in healthy humans.

Multiplate and TEG platelet mapping in a population of severely injured trauma patients

OBJECTIVES

The objectives of this study were to compare thromboelastography platelet mapping (TEG PM) with impedance aggregometry (Multiplate, MP) in a single trauma population and relate their results clinically.

BACKGROUND

Platelet function as measured by thromboelastography and impedance aggregometry demonstrates significant reductions that persist for days following traumatic injury. However, no study compares these devices and the correlation between them is not known.

METHODS

In level 1 trauma patients, TEG PM and MP were conducted at their initial presentation to the emergency department. Within-device repeatability and between-device association were determined using correlation analyses. Demographic variables, Injury Severity Score, blood product transfusion, laboratory test results and mortality rate were recorded.

RESULTS

Ninety-two patients were enrolled. Within-device repeatability was high for TEG PM and MP for arachidonic acid (AA) and adenosine diphosphate (ADP) activation pathways. When comparing TEG PM with MP, results correlated poorly in the ADP pathway (Spearman's rho = 0·11, P = 0·44) and moderately in the AA pathway (Spearman's rho = 0·56, P < 0·0001). TEG PM was predictive of blood product transfusion and correlated with increased base deficit, whereas MP was only predictive of mortality.

CONCLUSIONS

Intra-device variability was low for TEG PM and MP, but the two point-of-care devices measuring platelet function correlate poorly with each other in injured trauma patients. Each device also had different clinical associations.

A Comparison of Human Neutrophils Acquired from Four Experimental Models of Inflammation

Defects in neutrophil function have been implicated in a wide spectrum of clinical conditions. Several models are employed to study activated human neutrophils akin to those found at a site of inflammation. These include whole blood (WB) ex vivo stimulation with lipopolysaccharide (LPS) and in vivo techniques: cantharidin blister, skin windows and intra-dermal injection of UV-killed E.coli (UVKEc). Neutrophils obtained from these have never been compared. We compared the activation status of neutrophils from each technique in order to inform the optimal model for use in human studies. Healthy male volunteers were randomised to undergo one of the four techniques (n = 5/group). LPS: WB stimulated with 1ng/ml of LPS for 4 hours. Cantharidin: 12.5μl of 0.1% cantharidin elicited a single blister, aspirated at 24 hours. Skin windows: four 6mm mechanical-suction blisters created, de-roofed and an exudate-collection chamber placed over the windows for 4 hours before aspiration. UVKEc: 1.5 x 10⁷ UVKEc injected intra-dermally. A single 10mm mechanical-suction blister formed and aspirated at 4 hours. Unstimulated WB used as the control. Flow cytometry was used to determine activation status using CD16, CD11b, CD54, CD62L and CD88. Functional status was assessed with a phagocytosis assay. The pattern of neutrophil activation was similar in all models. Neutrophil CD11b was elevated in all models, most markedly in UVKEc (p<0.0001), and CD54 was also elevated but only significant in the LPS model (p = 0.001). CD62L was significantly reduced in all 4 models (p<0.0001) and CD88 was also suppressed in all. There were no changes in CD16 in any model, neither was there any significant difference in the phagocytic capacity of the neutrophils. In summary, there are no significant differences in activation marker expression or phagocytic capacity in the neutrophils obtained from each technique. Therefore we believe whole blood stimulation is the best model in experimentally challenging inpatient populations.

Can we use photography to estimate radiation interception by a crop canopy?

Accuracy of determining radiation interception, and hence radiation use efficiency, depends on the method of measuring photosynthetically active radiation intercepted. Methods vary, from expensive instruments such as Sunfleck ceptometers to simple methods such as digital photography. However, before universal use of digital photography there is need to determine its reliability and compare it with conventional, but expensive, methods. In a series of experiments at Lincoln, New Zealand, canopy development for barley, wheat, white clover and four forage brassica species was determined using both digital photographs and Sunfleck ceptometer. Values obtained were used to calculate conversion coefficient (Kf/Ki) ratios between the two methods. Digital photographs were taken at 45° and 90° for barley, wheat and white clover and at only 90° for brassicas. There was an interaction of effects of crop and cultivar for the cereal crops. Barley closed canopies earlier than wheat, and 'Emir' barley and 'Stettler' wheat had consistently higher canopy cover than 'Golden Promise' and 'HY459', respectively. Canopy cover was consistently larger at 45° than 90° for cereals. However, for white clover, the angle of digital photography was not important. There was also an interaction between effects of species and method of determining canopy cover for brassicas. Photographs gave higher cover values than ceptometer for forage rape and turnip, but the relationship was variable for forage kale and swede. Kf/Ki ratios of 1.0-1.10 for cereals, white clover and forage rape and turnip show that digital photographs can be used to estimated radiation interception, in place of Sunfleck ceptometer, for these crops.

Early postoperative bleeding in polytrauma patients treated with fondaparinux: literature review and institutional experience

Surgery for pelvic or acetabular fractures carries a high risk of deep-vein thrombosis (DVT). Reports indicate that fondaparinux is a more effective thromboprophylactic agent than low molecular weight heparin (LMWH) after major orthopaedic surgery. The safety and efficacy of fondaparinux was evaluated in a new protocol used for DVT prophylaxis. One hundred and twenty seven patients with pelvic or acetabular fractures received either fondaparinux or enoxaparin and were analysed in a historical non-concurrent study. Specific review points included clinical deep-vein thrombosis (DVT) or pulmonary embolism (PE) and evidence of adverse effects such as bleeding or allergic reactions. Two patients that received enoxaparin were found to have a DVT and one patient had a PE. There was no documented DVT or PE in patients that received fondaparinux. The mean number of units of blood transfused postoperatively was higher in the enoxaparin group; however, multivariate regression modelling demonstrated no significant difference between the groups. The most current large randomised controlled studies investigating the administration of fondaparinux following joint arthroplasty or hip fracture surgery, have demonstrated a slight increase or a similar number of bleeding events in patients treated with fondaparinux when compared to those treated with enoxaparin. The current report supports that fondaparinux, in patients with pelvic and acetabular fractures, can be equally effective as enoxaparin and not associated with adverse bleeding events.

The value of the Duke Activity Status Index (DASI) in predicting ischaemia in myocardial perfusion scintigraphy - a prospective study

BACKGROUND

Functional capacity assessment may be a useful tool to stratify patients according to risk of coronary artery disease (CAD). The Duke Activity Status Index (DASI) is a functional assessment based on activities of daily living and cardiovascular fitness, assessed using a self-administered questionnaire.

MATERIAL AND METHODS

We assessed the relationship between established clinical risk factors for CAD and the DASI with results of myocardial perfusion scintigraphy (MPS). The MPS results used in the analysis were the presence of reversible ischaemia and the resting left ventricular ejection fraction (LVEF). A DASI self-administered questionnaire was completed by 117 consecutive participants, and a patient history was taken to ascertain established risk factors. All participants underwent a stress test, and myocardial perfusion scintigraphy was performed. Statistical analysis consisted of logistic and linear regression using a statistical software package.

RESULTS

The DASI was the only factor that correlated significantly with reversible ischaemia on MPS. None of the previously established risk factors had a significant association with reversible ischaemia within the model. Our study found a potential relationship between the DASI score and the left ventricular ejection fraction (LVEF) although this was not statistically significant.

CONCLUSIONS

Our study findings suggest that the DASI may represent a powerful tool for risk stratification prior to investigation of CAD. A further study with a larger sample size will be required to investigate the predictive value of the DASI and the association with LVEF.

X-ray diffuse scattering measurements of nucleation dynamics at femtosecond resolution

Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process.

Ultrafast bond softening in bismuth: mapping a solid's interatomic potential with X-rays

Intense femtosecond laser excitation can produce transient states of matter that would otherwise be inaccessible to laboratory investigation. At high excitation densities, the interatomic forces that bind solids and determine many of their properties can be substantially altered. Here, we present the detailed mapping of the carrier density-dependent interatomic potential of bismuth approaching a solid-solid phase transition. Our experiments combine stroboscopic techniques that use a high-brightness linear electron accelerator-based x-ray source with pulse-by-pulse timing reconstruction for femtosecond resolution, allowing quantitative characterization of the interatomic potential energy surface of the highly excited solid.

The site of action of epidurally administered opioids and its relevance to postoperative pain management

The use of epidurally administered opioids to control postoperative pain is a well established and widely accepted technique. However, despite this longstanding use, there is still an ongoing debate concerning the site of action of the opioids used. Some argue that analgesia is mediated by a spinal mechanism and others that a supraspinal mechanism is responsible. On close inspection of the evidence it becomes apparent that epidural opioids act predominantly spinally when administered as a bolus, and predominantly supraspinally when administered as a continuous infusion. A concentration of 10 microg x ml(-1) appears to be the threshold at which epidurally administered fentanyl can elicit segmental analgesia, a value which may have significant clinical applications. The evidence supporting a synergistic relationship between epidural opioids and local anaesthetics is weak and unsupported by a plausible physiological mechanism. Thus the 'threshold concentration' of approximately 10 microg x ml(-1) is unlikely to be lowered by co-administering opioids with local anaesthetics.

XAS-Collect: a computer program for X-ray absorption spectroscopic data acquisition

A computer program for X-ray absorption spectroscopy (XAS) data acquisition, called XAS-Collect, is described. The software employs the X Windows system to provide a pull-down menu, dialog-box style of graphical user interface. The software provides state-of-the-art features while still being sufficiently simple for novice users.

Structure of the molybdenum site of Rhodobacter sphaeroides biotin sulfoxide reductase

Conditions for heterologous expression of Rhodobacter sphaeroides biotin sulfoxide reductase in Escherichia coli were modified, resulting in a significant improvement in the yield of recombinant enzyme and enabling structural studies of the molybdenum center. Quantitation of the guanine and the molybdenum as compared to that found in R. sphaeroides DMSO reductase demonstrated the presence of the bis(MGD)molybdenum cofactor. UV-visible absorption spectra were obtained for the oxidized, NADPH-reduced, and dithionite-reduced enzyme. EPR spectra were obtained for the Mo(V) state of the enzyme. X-ray absorption spectroscopy at the molybdenum K-edge has been used to probe the molybdenum coordination of the enzyme. The molybdenum site of the oxidized protein possesses a Mo(VI) mono-oxo site (Mo=O at 1.70 A) with additional coordination by approximately four thiolate ligands at 2.41 A and probably one oxygen or nitrogen at 1.95 A. The NADPH- and dithionite-reduced Mo(IV) forms of the enzyme are des-oxo molybdenum sites with approximately four thiolates at 2.33 A and two different Mo-O/N ligands at 2.19 and 1.94 A.

Reduction and coordination of arsenic in Indian mustard

The bioaccumulation of arsenic by plants may provide a means of removing this element from contaminated soils and waters. However, to optimize this process it is important to understand the biological mechanisms involved. Using a combination of techniques, including x-ray absorption spectroscopy, we have established the biochemical fate of arsenic taken up by Indian mustard (Brassica juncea). After arsenate uptake by the roots, possibly via the phosphate transport mechanism, a small fraction is exported to the shoot via the xylem as the oxyanions arsenate and arsenite. Once in the shoot, the arsenic is stored as an As(III)-tris-thiolate complex. The majority of the arsenic remains in the roots as an As(III)-tris-thiolate complex, which is indistinguishable from that found in the shoots and from As(III)-tris-glutathione. The thiolate donors are thus probably either glutathione or phytochelatins. The addition of the dithiol arsenic chelator dimercaptosuccinate to the hydroponic culture medium caused a 5-fold-increased arsenic level in the leaves, although the total arsenic accumulation was only marginally increased. This suggests that the addition of dimercaptosuccinate to arsenic-contaminated soils may provide a way to promote arsenic bioaccumulation in plant shoots, a process that will be essential for the development of an efficient phytoremediation strategy for this element.

Identifying left lower lobe pneumonia at chest radiography: performance of family practice residents before and after a didactic session

RATIONALE AND OBJECTIVES

The authors sought to determine whether the lateral chest radiograph is helpful in identifying left lower lobe pneumonia among inexperienced readers.

MATERIALS AND METHODS

The authors selected all patients who presented to a family practice training program with radiologic and clinical evidence of left lower lobe pneumonia (n = 65). They then selected an equal number of patients in whom chest radiographs were taken to "rule out pneumonia" and were found to be normal. Eight 1st-year family practice residents were asked to read the radiographs before and after a didactic session that emphasized lateral chest radiograph interpretation. The radiographs were presented under two viewing conditions: posteroanterior (PA) only versus PA and lateral. Receiver operating characteristic (ROC) curve methods were used to compare the effect of both the didactic session and the viewing condition on diagnostic accuracy.

RESULTS

There were no significant differences in performance before and after the didactic session and no differences between the two viewing conditions. After including only abnormal radiographs that demonstrated the "spine sign" (an apparent increased opacification of the lower vertebral bodies on the lateral view), the residents performed better when presented with both PA and lateral radiographs than when presented with the PA radiograph only (area under ROC curve, .8158 vs .7418, respectively; P = 0.24).

CONCLUSION

In patients with left lower lobe pneumonia whose radiographs demonstrated the spine sign, diagnostic accuracy improved when the lateral chest radiograph was viewed.

The independent role of cytomegalovirus as a risk factor for invasive fungal disease in orthotopic liver transplant recipients. Boston Center for Liver Transplantation CMVIG-Study Group. Cytogam, MedImmune, Inc. Gaithersburg, Maryland

PURPOSE

To assess impact of cytomegalovirus (CMV) donor-recipient serostatus, infection, or disease on development of invasive fungal infection in orthotopic liver transplant recipients.

PATIENTS AND METHODS

An analysis of prospectively collected data in 146 liver transplant recipients (intention to treat cohort) from 4 tertiary care, university-affiliated transplant centers in Boston (Boston Center for Liver Transplantation). Patients were observed for 1 year after transplantation for the development of CMV infection, CMV disease, CMV pneumonia, as well as for the development of opportunistic fungal infections, graft survival, and mortality. Weekly cultures were taken of urine and throat and every other week of buffy coat for CMV for 2 months, then monthly for 6 months, at 1 year, and at the time of any clinical illness. Pre- and posttransplant variables including CMV-serostatus of donor and recipient, fungal isolation from sterile body sites, fungemia, bacteremia, antibiotic use, immunosuppression, treatment for rejection, and volumes of blood products were measured.

RESULTS

Survival analysis demonstrated that 36% of patients with CMV disease developed invasive fungal disease within the first year post-transplant compared with 8% of those without CMV disease (P < 0.0001). One-year mortality in patients with invasive fungal disease was 15 of 22 (68%) compared with 23 of 124 (19%) in those without invasive fungal disease (P < 0.001). A multivariable, time-dependent analysis demonstrated that being a CMV-seronegative recipient of a CMV-seropositive donor organ (P < 0.001), having bacteremia (P = 0.001), UNOS (United Network for Organ Sharing) status 4 (need for life support measures) at transplant (P = 0.002), and volume of platelets (P = 0.002) were independently associated with invasive fungal disease. Restriction of cases of invasive fungal disease to those that occurred more than 2 weeks after transplant demonstrated an association with CMV disease (P = 0.003), bacteremia (P = 0.003), need for life support (P = 0.03), and volume of blood products transfused (P = 0.02).

CONCLUSION

CMV disease or being a CMV-seronegative recipient of a CMV-seropositive donor organ is an important predictor for invasive fungal disease following orthotopic liver transplantation.

Recurrent bacterial peritonitis caused by Neisseria cinerea in a chronic ambulatory peritoneal dialysis (CAPD) patient

We present an unusual case of recurrent (chronic ambulatory peritoneal dialysis) CAPD-associated peritonitis caused by Neisseria cinerea. Using DNA restriction fragment length polymorphism (RFLP) analysis, we determined that the recurrent infection was caused by reinfection with a different N. cinerea strain rather than relapse with the index strain and that the probable origin of the reinfecting organism was the patient's upper respiratory tract.

Incidence and predictors of cytomegalovirus pneumonia in orthotopic liver transplant recipients. Boston Center for Liver Transplantation CMVIG Study Group

The incidence, predictors, and outcome of cytomegalovirus pneumonia in OLT recipients have not been well defined. We conducted an analysis of prospectively collected data from 141 OLT recipients who were included as part of a randomized, placebo-controlled trial of CMV immune globulin prophylaxis. Cytomegalovirus pneumonia was diagnosed in 13 of 141 (9.2%) OLT recipients during the first year posttransplant and was associated with a higher 1-year mortality compared with those recipients without CMV pneumonia (84.6 vs. 17.2%, P=0.0001). Univariate analysis demonstrated that CMV viremia (P=0.001), invasive fungal disease (P=0.0001), donor(+)/pretransplant recipient(-) CMV serologic status (P=0.013), abdominal operation (excluding retransplantation) after liver transplantation (P=0.0027), bacteremia (P=0.0105), and advanced United Network of Organ Sharing status (P=0.023) were associated with CMV pneumonia. Cytomegalovirus viremia was diagnosed in 11 of 13 patients with CMV pneumonia at a median of 11 days (range 1-66 days) before diagnosis of CMV pneumonia. In a multivariate analysis using a time-dependent, Cox proportional hazards model, CMV viremia (RR=8.6, 95% CI 1.8-39.7, P=0.0012), invasive fungal disease (RR=6.5, 95% CI 2.1-20.3, P=0.0001), and abdominal reoperation (RR=4.4, 95% CI 1.4-13.1, P=0.0043) were found to be independent predictors of CMV pneumonia. The attributable mortality associated with CMV pneumonia within the first year after liver transplantation for the patients with CMV pneumonia was 67.4%. Intensified measures for prevention of CMV should be considered for patients at high risk of developing CMV pneumonia.

Regulation of calcium-activated potassium channels by S-nitrosothiol compounds and cyclic guanosine monophosphate in rabbit coronary artery myocytes

BACKGROUND

The patch-clamp technique was used to study a large conductance, calcium-activated potassium channel (IK(Ca) in coronary arterial smooth muscle cells from rabbits. The properties of this channel are similar to those of IK(Ca) found in many types of vascular tissue. A brief single channel characterization of IK(Ca) in this tissue type has been completed for this study.

METHODS

The effects of S-nitrosothiol compounds on IK(Ca) were studied in cell-attached patches.

RESULTS

The probability of opening for IK(Ca) increased from 0.008 +/- 0.004 to 0.780 +/- 0.07 following application of S-nitroso-L-cysteine. S-nitroso-N-acetylpenicillamine (SNAP) also increased the probability of opening for IK(Ca) from 0.022 +/- 0.01 to 0.601 +/- 0.05. The probability of opening for IK(Ca) also increased from 0.026 +/- 0.01 to 0.809 +/- 0.02 following application of membrane-permeable analogs of cyclic guanosine monophosphate (cGMP) to the bath of cell-attached patches, suggesting that IK(Ca) in coronary artery smooth muscle cells is regulated by a cGMP-dependent mechanism. Rp-8-pCPT-cGMP, a protein kinase G inhibitor, blocked the effect of SNAP, an S-nitrosothiol compound.

CONCLUSIONS

These findings suggest that one of the effects of nitrosothiol compounds is the activation of IK(Ca) through a cGMP-dependent mechanism in coronary artery smooth muscle cells.

The present and future of hematopoietic cytokines in clinical practice

Hematologic toxicities can be a major problem in the delivery of some chemotherapy regimens. The way clinicians manage myelosuppression has evolved from a symptomatic approach to the use of cytokines to ameliorate or prevent anemia and neutropenia. Soon, new cytokines will be commercially available to manage thrombocytopenia. Cytokines are transforming oncology by permitting dose intensification through delivery of chemotherapy at the full dose and on time, as well as permitting high-dose chemotherapy. Clinical trials are also exploring the benefits of cytokines for myeloablative chemotherapy with cellular support (bone marrow transplantation or peripheral blood progenitor cell transplantation). Future applications of cytokines include ex vivo expansion and gene transfer therapy. For cancer patients, the ability to receive intensive doses of chemotherapy might mean improved survival rates.

Clinical evaluation and temperature monitoring in predicting viability in replantations

Experiences with temperature and clinical monitoring in a series of 111 patients with 188 revascularized digits were reviewed. Criteria for abnormal temperature monitoring were defined. Monitoring of only clinical parameters showed a sensitivity of 1.00 and specificity of .97, but this technique was time-consuming and required experienced interpretation of subtle clinical changes. Temperature monitoring gave a sensitivity of 1.00, while the specificity was only .61. Drops in temperature were frequently not associated with vascular problems. Review of digits with abnormal clinical or temperature monitoring showed five patterns of abnormality. The first three groups had either abnormal clinical or temperature monitoring, but all fingers survived without reexploration. The fourth and fifth groups showed abnormalities in both clinical and temperature monitoring; all but one finger were found to be nonviable. Combined clinical and temperature monitoring was highly effective in early prediction of vascular compromise, with a sensitivity of 1.00 and a specificity of .99. The authors recommend the use of temperature monitoring. If a temperature drop occurs, monitoring of the clinical parameters can then be done. If both temperature and clinical monitoring yield abnormal results after a specified time, intervention should be carried out.

Modification of receptive fields of posteriomedial barrel subfield neocortical single units by known concentrations of iontophoresed noradrenaline in the rat

Using quantitative electromechanical stimulation of vibrissae poststimulus time histograms were used to map the receptive fields of single units from laminae II/III (12 units), IV (24 units) and V (12 units) of the posteriomedial barrel subfield in urethane anaesthetized rats prior to, and during the iontophoresis of known concentrations of Noradrenaline. All units had multivibrissae receptive fields prior to noradrenaline iontophoresis with laminae II/III units having the smallest size of center and surround receptive field and laminae V the largest. Lamina IV showed the strongest center receptive field response probability magnitude (spikes/stimulus) and the shortest modal latency of evoked responses. Noradrenaline iontophoresis diminished the size of surround receptive fields in each lamina and additionally decreased the size of center receptive fields in laminae IV and V. In Lamina IV, in contrast to laminae II/III and V, response probability magnitude from center receptive field vibrissae was not significantly depressed whilst modal latency of the evoked response was significantly reduced.

In vitro activity of orally administered antimicrobial agents against Haemophilus influenzae recovered from children monitored longitudinally in a group day-care center

To determine whether the prevalence of resistance to commonly used oral antimicrobial agents varied over time, we compared the in vitro susceptibilities of 217 strains of Haemophilus influenzae recovered from nasopharyngeal secretions of children in a day-care center studied longitudinally between 1979 and 1987. The overall rate of beta-lactamase production in these strains was 18%, with rates of 57% in type b isolates (n = 21) and 14% in non-type b isolates (n = 196). The percentages of isolates for which MICs were less than or equal to 1.0 micrograms/ml for amoxicillin alone, amoxicillin in combination with clavulanic acid, and cefuroxime alone were 82, 92, and 93%, respectively. The percentage of strains for which cefaclor MICs were less than or equal to 1.0 micrograms/ml was only 0.5%. Isolates for which chloramphenicol MICs were greater than 2.0 micrograms/ml or for which trimethoprim-sulfamethoxazole MICs were greater than 0.5/9.5 micrograms/ml were uncommon: 1 and less than 1%, respectively. High concentrations of erythromycin alone and in combination with sulfisoxazole were required to inhibit the majority of test strains; there was no evidence of erythromycin-sulfisoxazole synergy. In vitro susceptibility to commonly used oral antimicrobial agents remained at a constant level when H. influenzae isolates collected from children in a day-care center during 1979 through 1983 were compared with strains collected during 1984 through 1987.

Disruption of neocortical lamina V neuronal bursts by serotonin in urethane anaesthetized rats

Time-shared high speed cyclic voltametry using carbon fibre multibarrelled microelectrodes was used to monitor the concentration of 5-Hydroxytryptamine administered by iontophoresis to locations in lamina V of Sm l neocortex and to record spontaneous neuronal spike activity. In the absence of 5-Hydroxytryptamine at any one recording location the firing of two or more individual units was seen to be synchronized so that the pattern of multi-unit activity consisted of synchronized clusters of spike activity interspersed with period of neuronal silence. The repetition rate of such clusters of neuronal activity was seen to be between 0.5 and 4Hz. Maximum concentrations of 2.7 x 10(-7) M 5-Hydroxytryptamine produced by iontophoresis disrupted synchronized neuronal cluster activity. 5-Hydroxytryptamine at a concentration of 6.2 x 10(-8) M resulted in a greater than 50% inhibition of activity for 47 single units but a change in firing pattern from cluster restricted high frequency activity to a continuous mode of firing for a separate population of 11 units. Intraperitoneal administration of P-Chloroamphetamine produced similar changes of neuronal firing and hence loss of synchrony.

Bilateral receptive fields of cells in rat Sm1 cortex

Single cells in the primary somatosensory (Sm1) cortex were investigated for responses to bilateral hindpaw stimulation in Wistar rats anaesthetised by continuous intravenous administration of Althesin. Fifty-one percent of cells sampled (N = 134) responded to equivalent punctate mechanical stimuli delivered to both the contralateral and ipsilateral hindpaws under light anaesthesia. The distribution by cortical depth of cells with receptive fields (RFs) on both hindpaws was not significantly different from cells which had only contralateral RFs. No cell was found with a purely ipsilateral RF. For 86% of cells tested (N = 44) the ipsilateral RF was partly or completely homologous with areas within the contralateral RF. The sizes of ipsilateral RFs were smaller on 66% of occasions when tested against their contralateral RFs. Modal latencies to ipsilateral mechanical stimulation were longer than to contralateral stimulation (34.1 +/- 9.1 ms (S.D) cf. 26.4 +/- 7.2 ms, N = 44). Ipsilateral RFs were lost for 77% of cells tested following a 33% increase in anaesthetic infusion rate. Conditioning mechanical stimuli applied to the centre receptive field (CRF) on the ipsilateral hindpaw reduced or abolished a cell's responses to equivalent test stimuli applied to it's contralateral CRF with C-T intervals of 20-200 ms. Conditioning stimuli applied to the CRF contralateral to the cell reduced or abolished responses to test stimuli on the cell's ipsilateral CRF using C-T intervals of 0-900 ms. Responses in one cortex to stimulation of the ipsilateral hindpaw were unaffected by elimination of responses from the same hindpaw in the opposite contralateral Sm1 cortex, where responses had been suppressed by topical Lignocaine administration. Retrograde transport of horseradish peroxidase from hindpaw Sm1 cortex labelled many cells in homolateral thalamus, but failed to label cells in the entire forebrain contralateral to the injection site. It is concluded that direct crossed thalamo-cortical and callosal Sm1-Sm1 pathways do not contribute to the production of hindpaw ipsilateral receptive fields.

Influence of anesthesia on spontaneous activity and receptive field size of single units in rat Sm1 neocortex

Spontaneous and cutaneously driven unit activity was recorded in the hindfoot region of rat Sm1 neocortex under controlled intravenous infusion, at three selected rates, of the steroid anesthetic agent Althesin. Increasing depth of anesthesia decreased average spontaneous firing rates of 67 single units from 2.5 to 11 Hz during light anesthesia to 0 to 2.5 Hz in deep anesthesia. Thresholds to cutaneous stimulation for 58 units were innocuous (from 15 to 190 micron) using a 5-ms ramp displacement of the skin in the center receptive field. Responses from 13 sites on the hindfoot were classified according to response probability for each of the 58 units in reply to stimuli at 1.5 times center receptive field threshold. Small receptive fields were seen only under conditions of deep anesthesia, considerable expansion of both center and excitatory surrounds occurring with lighter anesthesia. Mean values for total receptive field size (center plus surround excitatory receptive field) were 10.8, 7.8, and 3.4 sites, respectively, for light, moderate, and deep anesthesia. The size of the receptive field was also influenced by stimulus repetition rate; moderate increases of this and anesthetic depth could eliminate substantial receptive fields. Surround inhibition of evoked activity was more effective in deeper anesthesia with little effect in light anesthesia. We suggest that receptive field expansion in light anesthesia arises from a relative increase in excitability of afferent pathways and an accompanying increase in the preponderance of surround excitation vis à vis surround inhibition.

Employee withdrawal and job satisfaction in community residential facilities for mentally retarded persons

This study was conducted to provide information concerning employee stability in community residential facilities serving mentally retarded persons. Information was collected on turnover, length of service, absenteeism, job satisfaction, and increased overhead costs as a consequence of the turnover rate for 21 randomly selected small and large community residential facility organizations that operated a total of 47 living units in Tennessee. Subjects included all house managers (full-time and relief) and administrator/supervisors in the 21 organizations for fiscal year 1978-1979. The results revealed a significant problem of controllable turnover of direct-service employees. The major factors contributing to this problem appeared to be (a) a lack of effective methods to orient, integrate, and maintain new staff members, (b) low pay and wide variations for amount and kind of work to be accomplished, and (c) a lack of training and support systems to deal with behavior problems presented by some residents.

Carotid sinus baroreceptor reflex control of the circulation in medial sclerotic and renal hypertensive rabbits and its modification by the aortic baroreceptors

We studied the reflex control of blood pressure, heart rate, and hindlimb vascular resistance by the carotid sinus baroreceptors in normal (N), experimental renal hypertensive (RH, one kidney renal wrap model), and medial sclerotic (MS) rabbits under urethane anaesthesia using an isolated perfused carotid sinus preparation and auto-perfused hindlimb. The contralateral carotid sinus was denervated. Compared to N rabbits, the blood pressure and hindlimb vascular resistance of RH and MS rabbits were significantly elevated at all carotid sinus pressures 15 weeks after inducing the disease process. The maximum gains of the curves relating carotid sinus pressure to vascular resistance were significantly elevated in the MS and RH rabbits, but those relating carotid sinus pressure to heart rate were significantly reduced. The changes were greatest in the RH group in which the responses also were set to a higher carotid sinus pressure. In the three groups, division of the aortic nerves produced different changes in the sigmoid curves relating carotid sinus pressure to heart rate, blood pressure, and vascular resistance. There was a linear relationship between blood pressure and basal vascular resistance (correlation coefficient 0.88).

Baroreflex sensitivity in rabbits during the development of experimental renal hypertension and medial sclerosis

Baroreflex sensitivity was assessed in 9 normotensive (N), 8 renal wrap (one kidney model, RH) and 16 medial sclerotic rabbits (MS, fed on calciferol 50,000 i.u. and calcium lactate 1g for 10 days) before (mean BP;N, 79 +/- 3.3 mm Hg; RH, 80 +/- 7.4 mm Hg; and MS, 83 +/- 1.0 mm Hg) and at monthly intervals for up to 16 weeks after the induction of the disease processes (mean BP;N, 87 +/- 3.9 mm Hg; RH, 127 +/- 7.2 mm Hg and MS, 99 +/- 3.8 mm Hg). Blood pressure was elevated by i.v. phenylephrine (5 and 10 micrograms.kg-1) or angiotensin (250 ng.kg-1) and baroreflex sensitivity assessed by the increase of pulse interval per unit rise of pressure. The pressor response was greater in the RH and MS than in the N rabbits. The baroreflex sensitivity showed a progressive reduction with time and with the elevation of blood pressure in both MS and RH rabbits. The difference was significantly greater (P < 0.01) than in the aged related control rabbits (P < 0.05). There was an inverse relationship between baroreflex sensitivity and the pressor response in MS rabbits. Results indicated progressive baroreceptors dysfunction in hypertensive and medial sclerotic rabbits.

Time-course of the reduction of baroreceptor sensitivity in experimental hypertensive rabbits

1. Hypertension was produced experimentally in three groups of rabbits by atherosclerosis, meical sclerosis and renal encapsulation. 2. The sensitivity of afferent baroreceptor fibre recordings, obtained from an isolated perfused aortic arch preparation, was reduced in all three treated groups. 3. The reduction of baroreceptor sensitivity was directly related to the increase in the lability of the blood pressure in the intact animal and to the reduction of the distensibility of the perfused region. 4. There was a closer relationship between the length of time of rabbits had been hypertensive and the reduction in the baroreceptor sensitivity, than to the level of their blood pressure. 5. The reduction of baroreflex sensitivity obtained by the infusion of phenylephrine was also directly correlated with the period of the hypertension. 6. Baroreceptor resetting occurred to a higher pressure in the renal hypertensive group.