Altered transcriptomic immune responses of maintenance hemodialysis patients to the COVID-19 mRNA vaccine

Background

End-stage renal disease (ESRD) patients experience immune compromise characterized by complex alterations of both innate and adaptive immunity, and results in higher susceptibility to infection and lower response to vaccination. This immune compromise, coupled with greater risk of exposure to infectious disease at hemodialysis (HD) centers, underscores the need for examination of the immune response to the COVID-19 mRNA-based vaccines.

Methods

The immune response to the COVID-19 BNT162b2 mRNA vaccine was assessed in 20 HD patients and cohort-matched controls. RNA sequencing of peripheral blood mononuclear cells was performed longitudinally before and after each vaccination dose for a total of six time points per subject. Anti-spike antibody levels were quantified prior to the first vaccination dose (V1D0) and 7 d after the second dose (V2D7) using anti-spike IgG titers and antibody neutralization assays. Anti-spike IgG titers were additionally quantified 6 mo after initial vaccination. Clinical history and lab values in HD patients were obtained to identify predictors of vaccination response.

Results

Transcriptomic analyses demonstrated differing time courses of immune responses, with prolonged myeloid cell activity in HD at 1 wk after the first vaccination dose. HD also demonstrated decreased metabolic activity and decreased antigen presentation compared to controls after the second vaccination dose. Anti-spike IgG titers and neutralizing function were substantially elevated in both controls and HD at V2D7, with a small but significant reduction in titers in HD groups (p<0.05). Anti-spike IgG remained elevated above baseline at 6 mo in both subject groups. Anti-spike IgG titers at V2D7 were highly predictive of 6-month titer levels. Transcriptomic biomarkers after the second vaccination dose and clinical biomarkers including ferritin levels were found to be predictive of antibody development.

Conclusions

Overall, we demonstrate differing time courses of immune responses to the BTN162b2 mRNA COVID-19 vaccination in maintenance HD subjects comparable to healthy controls and identify transcriptomic and clinical predictors of anti-spike IgG titers in HD. Analyzing vaccination as an in vivo perturbation, our results warrant further characterization of the immune dysregulation of ESRD.

Funding

F30HD102093, F30HL151182, T32HL144909, R01HL138628. This research has been funded by the University of Illinois at Chicago Center for Clinical and Translational Science (CCTS) award UL1TR002003.

Megakaryocytes respond during sepsis and display innate immune cell behaviors

Megakaryocytes (MKs) are precursors to platelets, the second most abundant cells in the peripheral circulation. However, while platelets are known to participate in immune responses and play significant functions during infections, the role of MKs within the immune system remains largely unexplored. Histological studies of sepsis patients identified increased nucleated CD61+ cells (MKs) in the lungs, and CD61+ staining (likely platelets within microthrombi) in the kidneys, which correlated with the development of organ dysfunction. Detailed imaging cytometry of peripheral blood from patients with sepsis found significantly higher MK counts, which we predict would likely be misclassified by automated hematology analyzers as leukocytes. Utilizing in vitro techniques, we show that both stem cell derived MKs (SC MKs) and cells from the human megakaryoblastic leukemia cell line, Meg-01, undergo chemotaxis, interact with bacteria, and are capable of releasing chromatin webs in response to various pathogenic stimuli. Together, our observations suggest that MK cells display some basic innate immune cell behaviors and may actively respond and play functional roles in the pathophysiology of sepsis.

Immune status and the efficacy of adjuvant radiotherapy for patients with localized Merkel cell carcinoma of the head and neck

PURPOSE

Immunosuppressed (IS) patients are at increased risk for developing Merkel cell carcinoma (MCC) with worsened outcomes compared to immunocompetent (IC) patients. We sought to determine the effects of immune status on the efficacy of adjuvant RT regarding OS for patients with stage I, II or III (localized) MCC of the head and neck.

METHODS/PATIENTS

The National Cancer Database was queried for patients with resected, localized MCC of the head and neck with known immune status. Kaplan-Meier methods were used to describe OS. Log-rank tests, multivariable Cox regression models and interaction effect testing were used to compare OS by subgroup categorized by patient and treatment factors including immune status and adjuvant RT receipt.

RESULTS

A total of 892 (89.6%) IC and 104 (10.4%) IS patients with MCC of the head and neck were included. Adjuvant RT was associated with improved 3-year OS rate for both IS patients (49.4% vs. 35.5%, p = 0.0467) and stage I/II IC patients (72.4% vs. 62.9%, p = 0.0092). Adjuvant RT was associated with decreased hazard of death (HR 0.77, 95% CI 0.62-0.95). Interaction effect testing did not demonstrate a difference in the efficacy of adjuvant RT on OS between IC and IS status (p = 0.157).

CONCLUSIONS

In this NCDB analysis, adjuvant RT was associated with decreased hazard of death for patients with localized MCC of the head and neck regardless of immune status and should be considered for both IS and IC patients.

Efficient Front-Rear Coupling in Neutrophil Chemotaxis by Dynamic Myosin II Localization

Efficient chemotaxis requires rapid coordination between different parts of the cell in response to changing directional cues. Here, we investigate the mechanism of front-rear coordination in chemotactic neutrophils. We find that changes in the protrusion rate at the cell front are instantaneously coupled to changes in retraction at the cell rear, while myosin II accumulation at the rear exhibits a reproducible 9-15-s lag. In turning cells, myosin II exhibits dynamic side-to-side relocalization at the cell rear in response to turning of the leading edge and facilitates efficient turning by rapidly re-orienting the rear. These manifestations of front-rear coupling can be explained by a simple quantitative model incorporating reversible actin-myosin interactions with a rearward-flowing actin network. Finally, the system can be tuned by the degree of myosin regulatory light chain (MRLC) phosphorylation, which appears to be set in an optimal range to balance persistence of movement and turning ability.

A New Test for the Detection of Direct Oral Anticoagulants (Rivaroxaban and Apixaban) in the Emergency Room Setting

Determining whether a patient has taken a direct oral anticoagulant (DOAC) is critical during the periprocedural and preoperative period in the emergency department. However, the inaccessibility of complete medical records, along with the generally inconsistent sensitivity of conventional coagulation tests to these drugs, complicates clinical decision making and puts patients at risk of uncontrollable bleeding. In this study, we evaluate the utility of inhibitor-II-X (i-II-X), a novel, microfluidics-based diagnostic assay for the detection and identification of Factor Xa inhibitors (FXa-Is) in an acute care setting.

DESIGN

First-in-human, 91-patient, single-center retrospective pilot study.

SETTING

Emergency room.

PATIENTS

Adult patients admitted into the emergency department, which received any clinician-ordered coagulation test requiring a 3.2% buffered sodium citrate blood collection tube.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma samples from patients admitted to the emergency department were screened for the use of FXa-Is, including apixaban and rivaroxaban, within the past 24 hours using our new i-II-X microfluidic test. i-II-X results were then compared with results from conventional coagulation tests, including prothrombin time (PT) and international normalized ratio (INR), which were ordered by treating clinicians, and an anti-Xa assay for rivaroxaban. The i-II-X test detected DOACs in samples collected from the emergency department with 95.20% sensitivity and 100.00% specificity. Unlike PT and INR, i-II-X reliably identified patients who had prolonged clotting times secondary to the presence of a FXa-I.

CONCLUSIONS

The i-II-X test overcomes the limitations of currently available coagulation tests and could be a useful tool by which to routinely screen patients for DOACs in emergency and critical care settings. Our new diagnostic approach is particularly relevant in clinical situations where medical records may be unavailable, or where precautions need to be taken prior to invasive interventions, such as specific reversal agent administration.

Trapped Chromatin Fibers Damage Flowing Red Blood Cells

Neutrophils are the most abundant white blood cells in the circulation and serve antimicrobial functions. One of their antimicrobial mechanisms involves the release of neutrophil extracellular traps (NETs), long chromatin fibers decorated with antimicrobial granular proteins that contribute to the elimination of pathogens. However, the release of NETs has also been associated with disease processes. While recent research has focused on biochemical reactions catalyzed by NETs, significantly less is known about the mechanical effect of NETs in circulation. Here, microfluidic devices and biophysical models are employed to study the consequences of the interactions between NETs trapped in channels and red blood cells (RBCs) flowing in blood over the NETs. It has been found that the RBCs can be deformed and ruptured after interactions with NETs, generating RBC fragments. Significant increases in the number of RBC fragments have also been found in the circulation of patients with conditions in which NETs have been demonstrated to be present in circulation, including sepsis and kidney transplant. Further studies will probe the potential utility of RBC fragments in the diagnostic, monitoring, and treatment of diseases associated with the presence of NETs in circulation.

Microfluidic arenas for war games between neutrophils and microbes

Measurements of neutrophil activities such as cell migration and phagocytosis are generally performed using low-content bulk assays, which provide little detail activity at the single cell level, or flow cytometry methods, which have the single cell resolution but lack perspective on the kinetics of the process. Here, we present a microfluidic assay for measuring the essential functions that contribute to the antimicrobial activity of neutrophils: migration towards the target, and killing of microbes. The assay interrogates the interactions between isolated human neutrophils and populations of live, proliferating microbes. The outcome is measured in a binary mode that is reflective of in vivo infections, which are either cleared or endure the host response. The outcome of the interactions is also characterized at single cell resolution for both the neutrophils and the microbes. We applied the assay to test the response of neutrophils from intensive care patients to live Staphylococcus aureus, and observed alterations of antimicrobial neutrophil activity in patients, including those with sepsis. By directly measuring neutrophil activity against live targets at high spatial and temporal resolution, this assay provides unique insights into the life-or-death contest shaping the outcome of interactions between populations of neutrophils and microbes.

Progressive mechanical confinement of chemotactic neutrophils induces arrest, oscillations, and retrotaxis

Neutrophils reach the sites of inflammation and infection in a timely manner by navigating efficiently through mechanically complex interstitial spaces, following the guidance of chemical gradients. However, our understanding of how neutrophils that follow chemical cues overcome mechanical obstacles in their path is restricted by the limitations of current experimental systems. Observations in vivo provide limited insights due to the complexity of the tissue environment. Here, we developed microfluidic devices to study the effect of progressive mechanical confinement on the migration patterns of human neutrophils toward chemical attractants. Using these devices, we identified four migration patterns: arrest, oscillation, retrotaxis, and persistent migration. The proportion of these migration patterns is different in patients receiving immunosuppressant treatments after kidney transplant, patients in critical care, and neonatal patients with infections and is distinct from that in healthy donors. The occurrence of these migration patterns is independent of the nuclear lobe number of the neutrophils and depends on the integrity of their cytoskeletal components. Our study highlights the important role of mechanical cues in moving neutrophils and suggests the mechanical constriction-induced migration patterns as potential markers for infection and inflammation.

Diagnosis of sepsis from a drop of blood by measurement of spontaneous neutrophil motility in a microfluidic assay

Current methods for the diagnosis of sepsis have insufficient precision, causing regular misdiagnoses. Microbiological tests can help diagnose sepsis but are usually too slow to have an impact on timely clinical-decision making. Neutrophils have high sensitivity to infections, yet measurements of neutrophil surface markers, genomic changes, and phenotype alterations have had only a marginal effect on sepsis diagnosis. Here, we report a microfluidic assay that measures the spontaneous motility of neutrophils in the context of plasma, in one droplet of blood. We measured the performance of the assay in two independent cohorts of critically ill patients suspected of sepsis. In the first cohort, we developed a machine-learning-based scoring system (sepsis score) that segregated patients with sepsis from those without sepsis. In the second cohort, we validated the sepsis score in a double-blinded, prospective case-control study. For the 42 patients across the two cohorts, the assay identified sepsis patients with 97% sensitivity and 98% specificity. The neutrophil assay could potentially be used to accurately diagnose and monitor sepsis in larger populations of at-risk patients.

Rheology of transgenic switchgrass reveals practical aspects of biomass processing

BACKGROUND

Mechanical properties of transgenic switchgrass have practical implications for biorefinery technologies. Presented are fundamentals for simple (thermo)mechanical measurements of genetically transformed switchgrass. Experimental basics are provided for the novice, where the intention is to promote collaboration between plant biologists and materials scientists.

RESULTS

Stem sections were subjected to two stress modes: (1) torsional oscillation in the linear response region, and (2) unidirectional torsion to failure. Specimens were analyzed while submerged/saturated in ethylene glycol, simulating natural hydration and allowing experimental temperatures above 100 °C for an improved view of the lignin glass transition. Down-regulation of the 4-Coumarate:coenzyme A ligase gene (reduced lignin content and altered monomer composition) generally resulted in less stiff and weaker stems. These observations were associated with a reduction in the temperature and activation energy of the lignin glass transition, but surprisingly with no difference in the breadth and intensity of the tan δ signal. The results showed promise in further investigations of how rheological methods relate to stem lignin content, composition, and functional properties in the field and in bioprocessing.

CONCLUSIONS

Measurements such as these are complicated by small specimen size; however, torsional rheometers (relatively common in polymer laboratories) are well suited for this task. As opposed to the expense and complication of relative humidity control, solvent-submersion rheological methods effectively reveal fundamental structure/property relationships in plant tissues. Demonstrated are low-strain linear methods, and also nonlinear yield and failure analysis; the latter is very uncommon for typical rheological equipment.

Jupiter's interior and deep atmosphere: The initial pole-to-pole passes with the Juno spacecraft

On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter's poles show a chaotic scene, unlike Saturn's poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth's Hadley cell. Near-infrared mapping reveals the relative humidity within prominent downwelling regions. Juno's measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter's core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content.

Convergent and Divergent Migratory Patterns of Human Neutrophils inside Microfluidic Mazes

Neutrophils are key cellular components of the innate immune response and characteristically migrate from the blood towards and throughout tissues. Their migratory process is complex, guided by multiple chemoattractants released from injured tissues and microbes. How neutrophils integrate the various signals in the tissue microenvironment and mount effective responses is not fully understood. Here, we employed microfluidic mazes that replicate features of interstitial spaces and chemoattractant gradients within tissues to analyze the migration patterns of human neutrophils. We find that neutrophils respond to LTB4 and fMLF gradients with highly directional migration patterns and converge towards the source of chemoattractant. We named this directed migration pattern convergent. Moreover, neutrophils respond to gradients of C5a and IL-8 with a low-directionality migration pattern and disperse within mazes. We named this alternative migration pattern divergent. Inhibitors of MAP kinase and PI-3 kinase signaling pathways do not alter either convergent or divergent migration patterns, but reduce the number of responding neutrophils. Overlapping gradients of chemoattractants conserve the convergent and divergent migration patterns corresponding to each chemoattractant and have additive effects on the number of neutrophils migrating. These results suggest that convergent and divergent neutrophil migration-patterns are the result of simultaneous activation of multiple signaling pathways.

Hydrocephalus and Ventriculoperitoneal Shunts: Modes of Failure and Opportunities for Improvement

Between 0.5 and 4 of every 1000 children are born with hydrocephalus. Hydrocephalus is an over-accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain, which can affect cognitive function, vision, appetite, and cranial nerve function. Left untreated, hydrocephalus can result in death. The current treatment for hydrocephalus uses ventriculoperitoneal (VP) shunts with valves to redirect CSF from the ventricles into the peritoneum. Shunt technology is limited by a number of complications, which include infection after implantation, shunt obstruction due to clot formation or catheter obstruction by scar tissue or choroid plexus, disconnection and tubing migration, and overdrainage or underdrainage of CSF due to valve malfunction. While modifications to surgical procedures and shunt design have been introduced, only modest improvements in outcomes have been observed. Here we provide an overview of hydrocephalus, VP shunts, and their modes of failure, and we identify numerous areas of opportunity for biomedical engineers and physicians to collaborate to improve the performance of VP shunts.

Neutrophil chemotaxis and transcriptomics in term and preterm neonates

Neutrophils play a crucial role in combating life-threatening bacterial infections in neonates. Previous studies investigating neonatal cell function have been limited because of restricted volume sampling. Here, using novel microfluidic approaches, we provide the first description of neutrophil chemotaxis and transcriptomics from whole blood of human term and preterm neonates, as well as young adults. Ex vivo percent cell migration, neutrophil velocity, and directionality to N-formylmethionyl-leucyl-phenylalanine were measured from whole blood using time-lapse imaging of microfluidic chemotaxis. Genome-wide expression was also evaluated in CD66b⁺ cells using microfluidic capture devices. Neutrophils from preterm neonates migrated in fewer numbers compared to term neonates (preterm 12.3%, term 30.5%, P = 0.008) and at a reduced velocity compared to young adults (preterm 10.1 μm/min, adult 12.7 μm/min, P = 0.003). Despite fewer neutrophils migrating at slower velocities, neutrophil directionality from preterm neonates was comparable to adults and term neonates. 3607 genes were differentially expressed among the 3 groups (P < 0.001). Differences in gene expression between neutrophils from preterm and term neonates were consistent with reduced pathogen recognition and antimicrobial activity but not neutrophil migration, by preterm neonates. In summary, preterm neonates have significant disturbances in neutrophil chemotaxis compared to term neonates and adults, and these differences in phenotype appear at the transcriptional level to target inflammatory pathways in general, rather than in neutrophil migration and chemotaxis.

Open Versus Endovascular or Hybrid Thoracic Aortic Aneurysm Repair

Thoracic aortic aneurysms are associated with significant morbidity and mortality. There are multiple underlying etiologies, including genetic abnormalities, that have important implications in their natural history. The variable histologic, anatomic, and clinical presentations necessitate careful consideration of available treatment options. Surgical repair of these aneurysms has been the mainstay of treatment; however, these approaches can carry a relatively high risk of morbidity and mortality. Endovascular approaches have now become first-line therapy for descending thoracic aneurysms, and with advancements in graft technology, endovascular approaches are being increasingly employed for hybrid repairs of the aortic arch and even the ascending aorta. However, to date, clinical outcomes from randomized trials and long-term follow-up are limited. As technology continues to advance, there is the potential for further integration of surgical and endovascular treatments so that patients have the best opportunity for a favorable outcome.

Neutrophil Interactions Stimulate Evasive Hyphal Branching by Aspergillus fumigatus

Invasive aspergillosis (IA), primarily caused by Aspergillus fumigatus, is an opportunistic fungal infection predominantly affecting immunocompromised and neutropenic patients that is difficult to treat and results in high mortality. Investigations of neutrophil-hypha interaction in vitro and in animal models of IA are limited by lack of temporal and spatial control over interactions. This study presents a new approach for studying neutrophil-hypha interaction at single cell resolution over time, which revealed an evasive fungal behavior triggered by interaction with neutrophils: Interacting hyphae performed de novo tip formation to generate new hyphal branches, allowing the fungi to avoid the interaction point and continue invasive growth. Induction of this mechanism was independent of neutrophil NADPH oxidase activity and neutrophil extracellular trap (NET) formation, but could be phenocopied by iron chelation and mechanical or physiological stalling of hyphal tip extension. The consequence of branch induction upon interaction outcome depends on the number and activity of neutrophils available: In the presence of sufficient neutrophils branching makes hyphae more vulnerable to destruction, while in the presence of limited neutrophils the interaction increases the number of hyphal tips, potentially making the infection more aggressive. This has direct implications for infections in neutrophil-deficient patients and opens new avenues for treatments targeting fungal branching.

Temporal gradients limit the accumulation of neutrophils towards sources of chemoattractant

Neutrophil trafficking during inflammation is a highly orchestrated process, coordinating neutrophil recruitment, sterilization of the wound, and inflammation resolution. Although the chemotactic signals guiding neutrophil recruitment to sites of inflammation are relatively well understood, mechanisms controlling cessation of neutrophil recruitment and return to normal tissue physiology remain undefined. To gain insights into these processes, we designed a microfluidic device with an array of chemoattractant reservoirs, which mimics the microenvironment in infected tissues, when multiple clusters of microbes are present. We monitored the temporal dynamics of neutrophil recruitment towards the chemoattractant reservoirs at single cell resolution, for 3 hours. We observed robust neutrophil recruitment that reached a plateau after 1.5 hours, despite the continuous presence of robust chemoattractant gradients around the reservoirs. The timing of the plateau was dependent on the geometry of the devices and was independent from the number of neutrophils. Based on these observations, we ruled out sub-population sensitivity, chemoattractant scavenging, and production of a self-limiting stop signal as potential mechanisms underpinning the plateau in neutrophil recruitment. We found a strong correlation between the temporal stabilization of concentration changes and the plateau in neutrophils recruitment. These results suggest that dynamic aspects of chemoattractant gradients are key for maximizing recruitment during the acute phase of infections and limiting the accumulation of neutrophils as soon as the infection is contained.

The International Haemovigilance Network Database for the Surveillance of Adverse Reactions and Events in Donors and Recipients of Blood Components: technical issues and results

BACKGROUND AND OBJECTIVES

The International Haemovigilance Network's ISTARE is an online database for surveillance of all adverse reactions (ARs) and adverse events (AEs) associated with donation of blood and transfusion of blood components, irrespective of severity or the harm caused. ISTARE aims to unify the collection and sharing of information with a view to harmonizing best practices for haemovigilance systems around the world.

MATERIALS AND METHODS

Adverse reactionss and adverse events are recorded by blood component, type of reaction, severity and imputability to transfusion, using internationally agreed standard definitions.

RESULTS

From 2006 to 2012, 125 national sets of annual aggregated data were received from 25 countries, covering 132.8 million blood components issued. The incidence of all ARs was 77.5 per 100 000 components issued, of which 25% were severe (19.1 per 100 000). Of 349 deaths (0.26 per 100 000), 58% were due to the three ARs related to the respiratory system: transfusion-associated circulatory overload (TACO, 27%), transfusion-associated acute lung injury (TRALI, 19%) and transfusion-associated dyspnoea (TAD, 12%). Cumulatively, 594 477 donor complications were reported (rate 660 per 100 000), of which 2.9% were severe.

CONCLUSIONS

ISTARE is a well-established surveillance tool offering important contributions to international efforts to maximize transfusion safety.

Technical Advance: Changes in neutrophil migration patterns upon contact with platelets in a microfluidic assay

Neutrophils are traditionally regarded as the "first responders" of the immune system. However, recent observations revealed that platelets often respond earlier to recruit and activate neutrophils within sites of injury and inflammation. Currently, platelet-neutrophil interactions are studied by intravital microscopy. Although such studies provide exceptional, physiologic in vivo data, they are also laborious and have low throughput. To accelerate platelet-neutrophil interaction studies, we have developed and optimized an ex vivo microfluidic platform with which the interactions between platelets and moving neutrophils are measured at single-cell level in precise conditions and with high throughput. With the use of this new assay, we have evaluated changes in neutrophil motility upon direct contact with platelets. Motility changes include longer distances traveled, frequent changes in direction, and faster neutrophil velocities compared with a standard motility response to chemoattractant fMLP. We also found that the neutrophil-platelet direct interactions are transient and mediated by CD62P-CD162 interactions, localized predominantly at the uropod of moving neutrophils. This "crawling," oscillatory neutrophil behavior upon platelet contact is consistent with previous in vivo studies and validates the use of this new test for the exploration of this interactive relationship.

Complications related to blood donation: a population-based study

BACKGROUND

Population-based data on the rate and outcome of complications related to blood donation are sparse.

STUDY DESIGN AND METHODS

Data from a survey conducted in 2003 in Aarhus County, Denmark, were used to assess the overall rate of donor complications. Additional nationwide data on moderate and severe donor complications were obtained from the Danish Register of Complications Related to Blood Donation, with records of all moderate and severe donor complications in Denmark occurring during the period 1997-2003.

RESULTS

In the regional survey, we identified 340 complications of any type among 41 274 donations, corresponding to a rate of 824/100,000 donations [95% confidence interval (CI): 741-916]. All complications were either needle injuries or vasovagal reactions. In the nationwide register, a total of 752 moderate and severe complications were recorded among 2,575,264 donations, corresponding to a rate of 29/100,000 donations (95% CI: 27-31). The rates of complications leading to long-term morbidity or disablement (> 5% loss of working capacity) were 5/100,000 donations (95% CI: 4.2-5.9) and 2.3/100,000 donations (95% CI: 1.8-2.9), respectively.

CONCLUSION

The risk of complications related to blood donation is low. However, attention towards donor complications is warranted, given the non-negligible rate of complications resulting in long-term morbidity and disablement.

Arthromitus (Bacillus cereus) symbionts in the cockroach Blaberus giganteus: dietary influences on bacterial development and population density

The filamentous spore-forming bacterium Arthromitus, discovered in termites, millipedes, sow bugs and other soil-dwelling arthropods by Leidy (1850), is the intestinal stage of Bacillus cereus. We extend the range of Arthromitus habitats to include the hindgut of Blaberus giganteus, the large tropical American cockroach. The occurrence and morphology of the intestinal form of the bacillus were compared in individual cockroaches (n=24) placed on four different diet regimes: diurnally maintained insects fed (1) dog food, (2) soy protein only, (3)purified cellulose only, and (4) a dog food-fed group maintained in continuous darkness. Food quality exerted strong influence on population densities and developmental stages of the filamentous bacterium and on fecal pellet composition. The most dramatic rise in Arthromitus populations, defined as the spore-forming filament intestinal stage, occurred in adult cockroaches kept in the dark on a dog food diet. Limited intake of cellulose or protein alone reduced both the frequency of Arthromitus filaments and the rate of weight gain of the insects. Spores isolated from termites, sow bugs, cockroaches and moths, grown on various hard surfaces display a branching mobility and resistance to antibiotics characteristic to group I Bacilli whose members include B. cereus, B. circulans, B. alvei and B. macerans. DNA isolated from pure cultures of these bacilli taken from the guts of Blaberus giganteus (cockroach), Junonia coenia (moth), Porcellio scaber (sow bug) and Cryptotermes brevis (termite) and subjected to Southern hybridization with a 23S-5S B. subtilis ribosomal sequence probe verified that they are indistinguishable from laboratory strains of Bacillus cereus.

Monitoring transfusion practice--a computerized procedure

As the description of transfusion practice over time requires the handling of massive amounts of data, and because the majority of records have until now been paper-based, little is known about the epidemiology of blood transfusion. Furthermore, most previous studies have collected data manually from patient records or from computerized registers created solely for study purposes. We describe a procedure for monitoring transfusion practices based exclusively upon the collection of data from the existing computerized registers. During the calendar years 1997 and 1998, more than 750 000 data records were collected from the blood transfusion registers, diagnosis and procedure registers, and clinical biochemistry registers at two university hospitals. Linking of the data required a unique and consistent identification of all data records. This was made possible by the national Personal Identification Number. In this way more than 98% of all transfusions could be identified and approximately 95% (77 950) could be connected to a principal diagnosis. The described procedure creates new opportunities for studies of transfusion practices both on a large scale and in richness of detail, and we propose to establish a network where transfusion practices data are available and comparable for individual departments, hospitals, whole regions, and possibly nations.

Thermophilic multidrug-resistant Campylobacter fetus infection with hypersplenism and histiocytic phagocytosis in a patient with acquired immunodeficiency syndrome

We present a case report of a patient who had acquired immunodeficiency syndrome (AIDS) and Campylobacter fetus infection with a number of unusual clinical and microbiological features. The patient had prominent gastrointestinal symptoms, splenic infarction, splenomegaly with hypersplenism, and hemophagocytic histiocytosis in the spleen and lymph nodes; the organism displayed growth on Campy-selective blood agar, thermotolerance, and resistance to quinolones, piperacillin/tazobactam, ceftazidime, and erythromycin.

Monitoring transfusion practices at two university hospitals

BACKGROUND AND OBJECTIVES

Considering the clinical importance of blood transfusions, the limited knowledge of transfusion practices is remarkable. New methods are needed to elucidate the observed variation of transfusion practices.

MATERIALS AND METHODS

All patients transfused or pretransfusion tested (i.e. at risk for blood transfusion) at two tertiary teaching hospitals during the full years of 1997 and 1998 were included in the study.

RESULTS

The observed practices contained substantial variance at the level of hospitals. The contributions to the total variance of the different specialities were highly significant, as was the contribution of hospitals to the variance in plasma and platelet transfusions. Significant interactions between hospitals and specialities were observed in transfusion of red cells, plasma and platelets.

CONCLUSION

To our knowledge this is the first survey of this size to combine transfusions, diagnoses and biochemical tests, exclusively based on an existing computerized register. The aim is to establish a basis for comparison of local transfusion practices with other commensurate hospitals and regions at a national (and international) level.

Otomastoiditis caused by Rhodococcus equi in a patient with AIDS

Rhodococcus equi is a well-recognized pathogen in veterinary medicine and a rare but well-documented cause of cavitary pneumonia in immunocompromised patients. Most cases of Rhodococcus equi infections in these patients involve the lungs. Otomastoiditis due to Rhodococcus equi is rare, and disseminated Rhodococcus equi with otomastoiditis has never been reported. We report a case of otomastoiditis with systemic dissemination due to Rhodococcus equi in a patient with AIDS.

Fluorodeoxyuridine causes bilomas after hepatic cryotherapy

BACKGROUND AND OBJECTIVES

Hepatic cryotherapy is a method of in situ cytodestruction used for unresectable liver tumours that can be combined with regional cytotoxic administration. We have used intra-arterial chemotherapy with 5-fluorouracil (5-FU) after hepatic cryotherapy but changed to 5-fluorodeoxyuridine (FUDR) because of the arterial toxicity of 5-FU. A new complication was seen.

METHODS

A retrospective case note study was performed of 130 patients who had undergone hepatic cryotherapy followed by regional chemotherapy at our centre. Seven patients received FUDR; 123 received 5-FU.

RESULTS

Biloma at the cryotherapy sites was seen in three patients in the FUDR group; two other patients in this group had other types of hepatic collection. Our previous experience with intra-arterial 5-FU in 123 patients after hepatic cryotherapy showed no evidence of this syndrome.

CONCLUSIONS

Intra-arterial FUDR should not be used after hepatic cryotherapy, at least during the immediate postoperative period.

Preoperative ultrasound to predict conversion in laparoscopic cholecystectomy

Laparoscopic cholecystectomy (LC) is the established treatment for symptomatic cholelithiasis. With its decreased postoperative stay, it is being performed increasingly in short-stay or outpatient settings. It is particularly important to identify preoperative factors that may predict conversion to open cholecystectomy (OC) at LC, with its concomitantly prolonged hospital recovery. In this series of 738 patients, the ultrasound features of stone size, gallbladder wall thickness, diameter of the common bile duct, number of stones, and the appearance of a contracted gallbladder were assessed preoperatively in all patients. The overall conversion rate was 3.5% (26 of 738). By logistic regression analysis, factors found to increase significantly the risk of conversion were patient age > 70 years (p < 0.01), a stone at least 20 mm in diameter (p < 0.05), a gallbladder wall thicker than 4 mm (p < 0.05), a common bile duct wider than 6 mm (p < 0.05), and contracted gallbladder on ultrasound (p < 0.02). The number of stones in the gallbladder was not significant. Using these risk factors, it was possible to divide patients into high- and low-risk groups. The 118 patients in the high-risk group had 18 of the 26 conversions, for a conversion rate of 15.3%. The 620 patients in the low-risk group had eight of the 26 conversions, for a conversion rate of 1.3%. This low-risk subgroup represented 84% of the series of 738 LC procedures and may have been suitable for outpatient LC. Using preoperative ultrasound, it is possible to predict patients who are at low risk of conversion and are suitable for ambulatory surgery.

Three methods of oxytocin-induced parturition and their effects of foals

OBJECTIVE

To compare effects of 3 oxytocin-based induction techniques on fetal and neonatal foals.

DESIGN

Prospective randomized controlled trial.

ANIMALS

16 pregnant mares.

PROCEDURE

Parturition was induced in mares by use of 3 treatments: group 1, 75 U of oxytocin, IM; group 2, 15 U of oxytocin, IM, q 15 minutes, for a maximum of 75 U; group 3, 75 U of oxytocin in 1 L of 0.9% NaCl solution IV (1 U/min), for a maximum of 75 U. Blood gas values and indices of vitality were measured in foals, and variables describing parturition were measured in mares.

RESULTS

Group-3 mares had a shorter interval from administration of oxytocin to rupture of the chorioallantois (OTCA) than group-2 mares. More foals were abnormal when the interval from oxytocin administration to delivery of the foal (OTDE) was > or = 60 minutes. Arterial blood gas values, measurements of vitality, and plasma cortisol concentrations did not differ among foals in various treatment groups. Increased interval for OTCA and OTDE resulted in higher neonatal PaCO2, and a longer interval for OTCA resulted in lower arterial pH. Time required for birth was shorter in mares with a dilated cervix. More abnormal foals than normal foals were delivered after premature placental separation or dystocia. Abnormal foals took longer to stand and suckle than normal foals. Interval from delivery to suckling was positively correlated with OTCA, OTDE, and PaCO2.

CLINICAL IMPLICATIONS

Method of oxytocin-induced parturition did not impact neonatal outcome. Interval from induction until parturition, degree of cervical dilatation, and intrapartum complications influenced induction success.

α1-acid glycoprotein and albumin in the spinal fluid of pregnant women

Pregnant women at term need a smaller dose of local anaesthetic to produce the same spinal anaesthesia as non-pregnant women. The aim of the study was to see whether the concentrations of binding proteins were reduced in spinal fluid in pregnant women. The concentrations of the binding proteins [Formula: see text] glycoprotein (AAG) and albumin were measured in plasma and spinal fluid from 20 pregnant and 20 non-pregnant women, ASA 1. Mean spinal fluid albumin was 3.13 micromol/1 in non-pregnant and 1.97 micromol/1 in pregnant women (95% confidence interval of the difference: 0.62 - 1.50). Mean spinal fluid AAG was 0.152 micromol/1 in non-pregnant and 0.081 micromol/1 in pregnant women (95% confidence interval of the difference: 0.030 - 0.100). The concentrations in plasma were also reduced in late pregnancy. All the changes were statistically significant. Since only a minor fraction of bupivacaine seems to be protein bound in spinal fluid these differences may have only a little influence on the free fraction and cannot be solely responsible for the increased sensitivity of pregnant women to spinal anaesthesia.

Interpretive criteria and quality control for antimicrobial susceptibility tests of levofloxacin

To confirm preliminary interpretive breakpoints for prototype 5 micrograms levofloxacin disks, 490 strains were tested in vitro using commercially manufactured disks. For in vitro susceptibility testing, 5 micrograms levofloxacin disks can be used with interpretive criteria of < or = 12 mm for resistant (MIC > or = 8.0 micrograms/ml) and > or = 16 mm for susceptible (MIC < or = 2.0 micrograms/ml). Proposed quality control limits for tests of levofloxacin are as follows: Escherichia coli ATCC 25922, zones 29-37 mm or MIC 0.008-0.03 microgram/ml; Pseudomonas aeruginosa ATCC 27853, zones 19-26 mm or MIC 0.5-2.0 micrograms/ml; Staphylococcus aureus ATCC 25923, zones 24-31 mm; Staphylococcus aureus ATCC 29213, MIC 0.06-0.25 microgram/ml and Enterococcus faecalis ATCC 29212, MIC 0.25-2.0 micrograms/ml.

Extraperitoneal 'laparoscopic' adrenalectomy

The technique of extraperitoneal 'laparoscopic' adrenalectomy is described in two cases, a left sided 1 cm Conn's tumour and a right sided 3.5 cm incidental non-functioning tumour. The extraperitoneal approach has the advantage of direct access to the adrenal gland without the need to mobilize abdominal organs, while maintaining all the advantages of minimal access surgery.

Physicians' influence on the decision to acquire magnetic resonance imagers in acute care hospitals

The influences of four principal types of decision makers on the acquisition of magnetic resonance imagers were measured in hospitals in Southern California, Oregon, and Washington. We propose that of the decision makers assessed, physicians had the most influence on the acquisition of magnetic resonance imagers.

Evidence against multiple premenstrual syndromes: results of a multivariate profile analysis of premenstrual symptomatology

The topic of a single vs multiple premenstrual syndromes has generated much discussion. In this study, multivariate profile analysis was used to determine whether or not physical and affective symptoms associated with the premenstrual syndrome (PMS) could be explained as the manifestation of one underlying pathophysiologic process. The premenstrual symptom profiles of 820 undergraduate students and 485 graduate students were evaluated. It was not possible to reject the null hypothesis of parallel profiles in most comparisons, suggesting that variability in the severity of premenstrual symptoms may be the result of individual differences in the expression of one underlying pathophysiologic process.