Associations Between Vancomycin Exposure and Acute Kidney Injury Within the Recommended Area Under the Curve Therapeutic Exposure Range Among Patients With Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Among patients with methicillin-resistant Staphylococcus aureus bacteremia, vancomycin-associated acute kidney injury increased as a function of the day 2 area under the curve (AUC), even for daily AUCs within the recommended therapeutic range (400–600). Further data are needed to determine if daily AUCs <400 can be maintained without compromising efficacy.

Environmental Correlates of Lyme Disease Emergence in Southwest Virginia, 2005-2014

Lyme disease is the most common tick-borne disease in North America. Though human infection is mostly transmitted in a limited geography, the range has expanded in recent years. One notable area of recent expansion is in the mountainous region of southwestern Virginia. The ecological factors that facilitate or constrain the range of human Lyme disease in this region remain uncertain. To evaluate this further, we obtained ecological data, including remotely sensed data on forest structure and vegetation, weather data, and elevation. These data were aggregated within the census block groups of a 9,153 km2 area around the cities of Blacksburg and Roanoke, VA, an area with heterogeneous Lyme disease transmission. In this geographic area, 755 individuals were reported to have Lyme disease in the 10 yr from 2006 to 2015, and these cases were aggregated by block group. A zero-inflated negative binomial model was used to evaluate which environmental variables influenced the abundance of Lyme disease cases. Higher elevation and higher vegetation density had the greatest effect size on the abundance of Lyme disease. Measures of forest edge, forest integrity, temperature, and humidity were not associated with Lyme disease cases. Future southward expansion of Lyme disease into the southeastern states may be most likely in ecologically similar mountainous areas.

International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

Sulfamethoxazole-Trimethoprim (Cotrimoxazole) for Skin and Soft Tissue Infections Including Impetigo, Cellulitis, and Abscess

Skin and soft tissue infections (SSTI) affect millions of people globally, which represents a significant burden on ambulatory care and hospital settings. The role of sulfamethoxazole-trimethoprim (SXT) in SSTI treatment, particularly when group A Streptococcus (GAS) is involved, is controversial. We conducted a systematic review of clinical trials and observational studies that address the utility of SXT for SSTI treatment, caused by either GAS or Staphylococcus aureus, including methicillin-resistant (MRSA). We identified 196 studies, and 15 underwent full text review by 2 reviewers. Observational studies, which mainly focused on SSTI due to S aureus, supported the use of SXT when compared with clindamycin or β-lactams. Of 10 randomized controlled trials, 8 demonstrated the efficacy of SXT for SSTI treatment including conditions involving GAS. These findings support SXT use for treatment of impetigo and purulent cellulitis (without an additional β-lactam agent) and abscess and wound infection. For nonpurulent cellulitis, β-lactams remain the treatment of choice.

Complicated Staphylococcus aureus Bacteremia (SAB) Is Associated with Genetic Variation in GLS2

Background

SAB is a serious, common infection. We used whole exome sequencing (WES) to examine the cumulative effect of coding variants in each gene on risk of complicated SAB in a discovery set of patients, and then evaluated the nominally significant genes in a replication set of patients using custom-capture sequencing.

Methods

The discovery set comprised 84 complicated SAB cases (endocarditis or bone/joint infection) frequency-matched by age (in deciles), sex, and bacterial clonal complex (CC5/30, CC8) to 84 uncomplicated SAB controls. All were white inpatients at Duke University. WES utilized Agilent SureSelect 72Mb capture kits, followed by sequencing on an Illumina HiSeq2000, alignment and base calling with a standard pipeline. The SKAT-O and EPACTS packages were used for gene-based association tests and logistic regression models with Firth bias correction, respectively. Both controlled for age, sex, and clonal complex as covariates. The replication set of 122 complicated SAB cases and 118 uncomplicated SAB controls was frequency matched by age, sex, and clonal complex. All were white Europeans collected by the Statens Serum Institute. An Agilent SureSelect 2Mb capture array captured genic sequence for 342 genes nominally associated with complicated SAB in discovery (SKAT-O P < 0.035). Sequencing and data analysis proceeded as for WES. A Bonferroni-corrected gene-based test P-value of 1.5×10^–4 determined significance in the replication set.

Results

One gene, GLS2, was significantly associated with complicated SAB in the replication set (P = 1.2 x 10^–4). The strongest single-variant association in all 342 genes was rs2657878 in GLS2 (p = 5×10⁻⁴). This variant is strongly correlated with a missense variant (rs2657879, p = 4.4x10^-3) in which the minor allele (associated here with complicated SAB) has previously been shown to reduce circulating glutamine levels.

Conclusion

Comprehensive examination of the coding sequence for association with complicated SAB in a two-stage discovery/replication design identified a novel candidate gene. GLS2 is an interesting candidate for complicated SAB due to its role in regulating glutamine production, a key factor in activation of T-cell production.

Disclosures

V. Fowler Jr., Pfizer, Novartis, Galderma, Novadigm, Durata, Debiopharm, Genentech, Achaogen, Affinium, Medicines Co., Cerexa, Tetraphase, Trius, MedImmune, Bayer, Theravance, Cubist, Basilea, Affinergy, Janssen, xBiotech, Contrafect: Consultant, Consulting fee; NIH, Basilea, MedImmune, Cerexa/Forest/Actavis/Allergan, Pfizer, Advanced Liquid Logics, Theravance, Novartis, Cubist/Merck; Medical Biosurfaces; Locus; Affinergy; Contrafect; Karius: Grant Investigator, Research grant; Green Cross, Cubist, Cerexa, Durata, Theravance; Debiopharm: Consultant, Consulting fee; UpToDate: author on several chapters, Royalties

The Emperor’s New Clothes: Prospective Observational Evaluation of the Association between the Day 2 Vancomycin Exposure and Failure Rates among Adult Hospitalized Patients with MRSA Bloodstream Infections (PROVIDE)

Background

Current guidelines recommend vancomycin (VAN) dosing to achieve AUC/MIC ratio ≥400 for patients (pts) with serious MRSA bloodstream infections (BSI), but supporting data were largely derived in single center retrospective studies. A recent study using a Bayesian approach to estimate the VAN AUC found that patients with MRSA BSI who had an AUC_DAY2/MIC_BMD ≥ 650 or an AUC_DAY2/MIC_ETEST ≥ 320 had lower incidences of failure (Clin Infect Dis 59:666, 2014). This study prospectively evaluated if these VAN AUC_DAY2/MIC targets were associated with lower incidences of failure (PROVIDE, Award number UM1AI104681, Antibacterial Resistance Leadership Group).

Methods

Prospective, multi-center (n = 14), observational study (2014–2106) of hospitalized adults with confirmed MRSA BSI treated with VAN ≥ 72h. Exclusion: (1) neutropenia; (2) cystic fibrosis; (3) renal replacement therapy; (4) APACHE-II score > 25; (5) previous MRSA BSI within 60 days. VAN exposures were estimated using maximum a posteriori probability procedure in ADAPT 5. MIC_BMD and MIC_ETEST were performed at a central laboratory. Outcomes: failure (30-day mortality or MRSA BSI ≥ 7 days); acute kidney injury (AKI), ≥1.5 × increase in serum creatinine (S_cr) among patients with a baseline S_CR < 2.0mg/dl. The study was powered at 80% to detect a 17.5% difference in failure between AUC_DAY2/MIC groups.

Results

Among the 265 evaluable patients, mean (SD) age was 61 (17) and APACHE-II was 12 (6). Endocarditis was definite/possible in 29%. The MIC_50/90 by BMD and ETEST were 1/1 and 1.5/1.5mg/l, respectively. Failure occurred in 18%; 26% had AKI. Mean (SD) VAN duration was 18 (14) days. Mean (SD) AUC_DAY2 was 586.9 (235.5) and 44% and 73% of patients achieved an AUC_DAY2/MIC_BMD ≥ 650 and AUC_DAY2/MIC_ETEST ≥ 320. In the multivariate analyses (Figure 1), failure was not significantly different between AUC_DAY2/MIC groups. In contrast, AKI was significantly more common in patients with an AUC_DAY2/ MIC_ETEST > = 320.

Conclusion

Achievement of higher VAN AUC_DAY2/MIC exposures for patients with MRSA BSIs were not associated with better outcomes and were found to result in increased AKI. Clinicians should assess the benefits vs. risks of using VAN regimens that confer high AUC_DAY2/MIC exposures for patients with MRSA BSIs.

Disclosures

T. P. Lodise Jr., allergan: Consultant, Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee and Speaker honorarium; medicines company: Consultant, Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee, Research support and Speaker honorarium; melinta: Consultant, Consulting fee; motif: Consultant and Scientific Advisor, Consulting fee; paratek: Consultant and Scientific Advisor, Consulting fee; nabriva: Consultant, Consulting fee; M. J. Zervos, Merck, Inc.: Investigator, Research grant; M. Scheetz, Bayer: Scientific Advisor, Consulting fee; V. Fowler Jr., Pfizer, Novartis, Galderma, Novadigm, Durata, Debiopharm, Genentech, Achaogen, Affinium, Medicines Co., Cerexa, Tetraphase, Trius, MedImmune, Bayer, Theravance, Cubist, Basilea, Affinergy, Janssen, xBiotech, Contrafect: Consultant, Consulting fee; NIH, Basilea, MedImmune, Cerexa/Forest/Actavis/Allergan, Pfizer, Advanced Liquid Logics, Theravance, Novartis, Cubist/Merck; Medical Biosurfaces; Locus; Affinergy; Contrafect; Karius: Grant Investigator, Research grant; Green Cross, Cubist, Cerexa, Durata, Theravance; Debiopharm: Consultant, Consulting fee; UpToDate: author on several chapters, Royalties

Doing the Same with Less: A Randomized, Multinational, Open-Label, Adjudicator-Blinded Trial of an Algorithm vs. Standard of Care to Determine Treatment Duration for Staphylococcal Bacteremia

Background

The appropriate duration of antibiotics for staphylococcal bloodstream infection (BSI) is unknown. An algorithm to identify patients with staphylococcal BSI who can be safely treated with shorter courses of therapy would improve care and reduce total antibiotic use.

Methods

Adult patients with staphylococcal BSI were randomized to treatment based on algorithm-based therapy (ABT) or to standard of care (SOC). Co-primary outcomes were clinical success, as determined by a blinded Adjudication Committee, and serious adverse event (SAE) rates. The prespecified secondary outcome measure was antibiotic days by treatment group, among patients without complicated BSI. Prespecified durations of therapy in ABT were: S. aureus BSI (SAB): uncomplicated: 14 days; complicated: 4–6 weeks. Coagulase-negative staphylococci BSI (CoNSB): simple (1 positive blood culture) (0–3 days), uncomplicated (&gt;1 positive blood culture) (5 days), complicated (7–28 days). Outcomes were compared using intention-to-treat principles. The target sample size was 500 patients, to ensure 90% power for establishing noninferiority within a margin of 15%.

Results

Between April 2011 and March 2017, 509 adults with suspected staphylococcal BSI at 16 sites in the US and Spain were randomized to ABT (N = 255) or SOC (N = 254). There were 116 patients with SAB (23%) and 385 (76%) with CoNSB (Figure 1). Overall success rate in the ABT group was 82.0% vs. 81.5% in the SOC group, difference 0.5%, 95% CI −5.2% to 6.1%. SAEs were reported in 32.9% of ABT vs. 28.3% of SOC patients (OR 1.2, 95% CI 0.9 to 1.8). Among evaluable patients without complicated BSI, mean duration of therapy was 4.4 days in the ABT group vs. 6.4 days in the SOC group (difference −2.0 days, 95% CI −3.3 to −-0.7, P = 0.003). Among patients with uncomplicated SAB, treatment durations were similar (15.3 days in ABT vs. 16.3 days in SOC, difference −1 day, 95% CI −3.89 to 1.91, P = 0.497), whereas for uncomplicated CoNSB, duration was shorter in the ABT group (5.3 days in ABT vs. 8.4 days in SOC, difference −3 days, 95% CI −4.87 to −1.34, P &lt; 0.001).

Conclusion

The use of a treatment algorithm for staphylococcal BSI was associated with significant reductions in duration of antibiotic therapy in patients without complicated BSI, without significant differences in overall success or SAEs.

Disclosures

V. Fowler Jr., NIH: Investigator, Contract HHSN272200900023C

Poor Positive Predictive Value of Lyme Disease Serologic Testing in an Area of Low Disease Incidence

BACKGROUND

Lyme disease is diagnosed by 2-tiered serologic testing in patients with a compatible clinical illness, but the significance of positive test results in low-prevalence regions has not been investigated.

METHODS

We reviewed the medical records of patients who tested positive for Lyme disease with standardized 2-tiered serologic testing between 2005 and 2010 at a single hospital system in a region with little endemic Lyme disease. Based on clinical findings, we calculated the positive predictive value of Lyme disease serology. Next, we reviewed the outcome of serologic testing in patients with select clinical syndromes compatible with disseminated Lyme disease (arthritis, cranial neuropathy, or meningitis).

RESULTS

During the 6-year study period 4723 patients were tested for Lyme disease, but only 76 (1.6%) had positive results by established laboratory criteria. Among 70 seropositive patients whose medical records were available for review, 12 (17%; 95% confidence interval, 9%-28%) were found to have Lyme disease (6 with documented travel to endemic regions). During the same time period, 297 patients with a clinical illness compatible with disseminated Lyme disease underwent 2-tiered serologic testing. Six of them (2%; 95% confidence interval, 0.7%-4.3%) were seropositive, 3 with documented travel and 1 who had an alternative diagnosis that explained the clinical findings.

CONCLUSIONS

In this low-prevalence cohort, fewer than 20% of positive Lyme disease tests are obtained from patients with clinically likely Lyme disease. Positive Lyme disease test results may have little diagnostic value in this setting.

A host-based RT-PCR gene expression signature to identify acute respiratory viral infection

Improved ways to diagnose acute respiratory viral infections could decrease inappropriate antibacterial use and serve as a vital triage mechanism in the event of a potential viral pandemic. Measurement of the host response to infection is an alternative to pathogen-based diagnostic testing and may improve diagnostic accuracy. We have developed a host-based assay with a reverse transcription polymerase chain reaction (RT-PCR) TaqMan low-density array (TLDA) platform for classifying respiratory viral infection. We developed the assay using two cohorts experimentally infected with influenza A H3N2/Wisconsin or influenza A H1N1/Brisbane, and validated the assay in a sample of adults presenting to the emergency department with fever (n = 102) and in healthy volunteers (n = 41). Peripheral blood RNA samples were obtained from individuals who underwent experimental viral challenge or who presented to the emergency department and had microbiologically proven viral respiratory infection or systemic bacterial infection. The selected gene set on the RT-PCR TLDA assay classified participants with experimentally induced influenza H3N2 and H1N1 infection with 100 and 87% accuracy, respectively. We validated this host gene expression signature in a cohort of 102 individuals arriving at the emergency department. The sensitivity of the RT-PCR test was 89% [95% confidence interval (CI), 72 to 98%], and the specificity was 94% (95% CI, 86 to 99%). These results show that RT-PCR-based detection of a host gene expression signature can classify individuals with respiratory viral infection and sets the stage for prospective evaluation of this diagnostic approach in a clinical setting.

A DNA vaccination regime including protein boost and electroporation protects cattle against foot-and-mouth disease

Protection against foot-and-mouth disease (FMD) using DNA technology has been documented for sheep and pigs but not for the highly susceptible species of cattle. Twenty-five Holstein Friesian cross-bred cattle were vaccinated twice, 21 days apart, with a DNA vaccine containing the capsid coding region (P1) along with the non-structural proteins 2A, 3C and 3D (pcDNA3.1/P1-2A3C3D) of O(1) Kaufbeuren alone or coated onto PLG (d,l-lactide-co-glycolide) microparticles. In some pcDNA3.1/P1-2A3C3D was also combined with an adjuvant plasmid expressing bovine granulocyte macrophage colony stimulating factor (GM-CSF). DNA vaccinations were administered intramuscularly with, or without, the use of electroporation and at 42 days post primary vaccination cattle received a protein boost of 146S FMD virus (FMDV) antigen and non-structural protein 3D. For comparison, four cattle were vaccinated with a conventional FMD vaccine and two more included as unvaccinated controls. Apart from those immunised with PLG microparticles all cattle were challenged with 10(5) TCID(50) cattle adapted O(1) Lausanne FMDV virus at day 93 post primary vaccination. All DNA vaccinated cattle regardless of regime developed good humoral and cell mediated responses prior to challenge. The best overall virus neutralising antibody, IFN-γ and clinical protection (75%) were seen in the cattle whereby the DNA was delivered by electroporation. In contrast, only 25% of cattle vaccinated with the DNA vaccine without electroporation were clinically protected. The addition of GM-CSF in combination with electroporation further improved the efficacy of the vaccine, as demonstrated from the reduction of clinical disease and virus excretions in nasal swabs. We thus demonstrate for the first time that cattle can be clinically protected against FMDV challenge following a DNA prime-protein boost strategy, and particularly when DNA vaccine is combined with GM-CSF and delivered by electroporation.

Daptomycin compared to standard therapy for the treatment of native valve endocarditis

INTRODUCTION

In a recent randomized trial of Staphylococcus aureus bacteremia and native valve endocarditis, daptomycin was found not inferior to standard therapy. We summarized findings in the subgroup of patients with endocarditis according to the Duke criteria.

METHODS

Patients were randomly assigned to receive daptomycin 6 mg/kg/day or standard therapy (vancomycin 1g every 12h or antistaphylococcal penicillin 2g every 4h, both with gentamicin 1mg/kg every 8h for the first 4 days). The primary end point was success in the modified intent-to-treat population 6 weeks after the end of therapy.

RESULTS

Fifty-three patients were included: 35 with right-sided endocarditis (RIE) and 18 with left-sided endocarditis (LIE). The success rates in patients with RIE were similar between daptomycin and the comparator (42% vs 44%). Patients with RIE with septic pulmonary infarcts responded similarly to treatment with daptomycin and standard therapy (60% vs 67%). In the LIE population, treatment success rates were poor in both arms (11% vs 22%).

CONCLUSION

Daptomycin is an efficacious and well-tolerated alternative to standard therapy in the treatment of RIE. Patients with LIE had a poor outcome regardless of the treatment received. Daptomycin is also effective in treating endocarditis with septic pulmonary infarcts.

Update on infective endocarditis

With infective endocarditis afflicting 15,000 patients each year and with a mortality rate that still hovers at almost 40%, the disease remains a very serious health problem. Surprisingly, the incidence has not declined over the last 30 years, and now with more health care interventions, such as pacer/defibrillators, and an increasingly elderly population with degenerative valvular heart disease, the number susceptible to endocarditis is actually increasing. Given the weak evidence for endocarditis prophylaxis, there remains a large population at risk. Much has been learned recently about the pathogenesis of endocarditis, including the role of endothelial damage, platelet adhesion, and microbial adherence to the vegetation or intact valvular tissue. Three-fourths of patients have preexisting structural heart disease. Once infection is manifest, major cardiac complications include congestive heart failure, embolization, mycotic aneurysms, renal dysfunction, and abscess formation. The diagnosis of endocarditis has been enhanced recently by modifications in the Duke criteria to include the use of transesophageal echocardiography and microbial antibody titers. Surgery continues to play an important role, with criteria for emergency, urgent, and early surgery now defined. The major organisms involved in infective endocarditis include streptococci and staphylococcus (representing 75% or so of all cases). Enterococcal infections account for many of the remaining cases, although small series and case reports suggest almost all organisms that infect humans can be implicated at times. A sizeable number of "culture-negative" cases still occur despite all the improvements in diagnostic methodology. Recent guidelines for the diagnosis, treatment, and management of infective endocarditis from the American Heart Association are reviewed and the issues surrounding prophylaxis are summarized. International cooperative databases are now being developed that hold promise for a continual reexamination of the epidemiology of this highly aggressive disease and may help provide sorely needed prospective trial data that will enhance our understanding and treatment.

Novel approaches to clinical trials: device-related infections

The explosive growth in the use of cardiac devices and the continued large number of thoracic operations produce a significant number of costly infectious complications. These infections represent a leading cause of death and disability after device implantation or surgery. Unfortunately, few objective data are available to validate the clinical epidemiology of surgical and device-related infections, and although the number of randomized trials is increasing, too few have tested strategies for prophylaxis or treatment, particularly in the cardiac arena. Because of the expected increase in invasive vascular procedures and device implantations, it is timely to consider innovative approaches to clinical research that will hasten the translation of effective therapeutic strategies and technologies into clinical practice. Because of the multidisciplinary nature of the care of patients undergoing thoracic surgery or device implantation, bringing together existing networks and several arms of the Federal government could rapidly advance this field to provide a definitive base of evidence to guide clinical practice and improve clinical outcomes. The remainder of the articles in this supplement discuss specific issues on the diagnosis and treatment of device-related or surgical infection. The purpose of this manuscript is to discuss issues about the design of studies and their organization.

Comparing patients' experience of mental health services in England: a five-Trust survey

The implementation of the Care Programme Approach (CPA) in English mental health services has been slow to proceed despite general support, both in England and in other countries, of its principles of good practice. This study set out to evaluate the implementation of the CPA directly from patients' experience using the "Your Treatment and Care" assessment tool. The results of a survey of 503 patients across five NHS Trusts in England showed that many patients did not have a copy of their care plan and had not been involved in the care planning procedure. Many reported shortcomings in their experience of their key worker and their psychiatrist. However, there was substantial variation in experience across services. "Your Treatment and Care" showed good internal reliability, was acceptable to users, and appeared to be able to access actual experiences better than a traditional "satisfaction" item. It appears to be very useful as a benchmarking tool and is now being used in services across the UK, the USA and Australia.

A new system for the measurement of displacements of the human body with widespread applications in human movement studies

This paper reports the development, construction and use of a new system for the measurement of linear kinematics in one, two or three dimensions. The system uses a series of rotary shaft encoders and inelastic tensioned strings to measure the linear displacement of key anatomical points in space. The system is simple, inexpensive, portable, accurate and flexible. It is therefore suitable for inclusion in a variety of motion analysis studies. Details of the construction, calibration and interfacing of the device to an IBM PC computer are given as is a full mathematical description of the appropriate measurement theory for one, two and three dimensions. Examples of the results obtained from the device during gait, running, rising to stand, sitting down and pointing with the upper limb are given. Finally it is proposed that, provided the constraints of the system are considered, this method has the potential to measure a variety of functional human movements simply and inexpensively and may therefore be a valuable addition to the methods available to the motion scientist.

Muscle length effect on the pendulum test

OBJECTIVE

An investigation of the effect of the length of knee extensor muscles on the pendulum test.

DESIGN

Descriptive. Statistical analysis utilized analysis of variance with planned comparisons.

SETTING

Community clubs and a stroke rehabilitation unit.

PARTICIPANTS

Twenty subjects aged 54 to 83 yrs, more than 6 weeks after stroke, and 31 healthy subjects aged 60 to 79 yrs.

OUTCOME MEASURES

Two tests: pendulum test and knee extensor muscle length test.

RESULTS

For both affected and intact legs, stroke subjects had significantly smaller angle of reversal (p < .001), peak angular velocity (p < .001), and maximum passive knee flexion (p < .001) than healthy subjects. When angle of reversal was normalized for passive knee flexion, there were no significant differences between healthy and stroke subjects. There were no significant differences in any variable between the intact and affected legs of the stroke subjects.

CONCLUSION

Soft tissue changes, rather than hyperreflexia, may explain the decreased angle of reversal and peak angular velocity in the stroke subjects studied.

Changes in postural sway and performance of functional tasks during rehabilitation after traumatic brain injury

OBJECTIVE

To investigate changes in postural sway while standing, walking parameters, and performance of functional tasks during rehabilitation in a group of traumatic brain injury (TBI) patients.

DESIGN

Descriptive.

SETTING

Inpatient brain injury rehabilitation unit.

PARTICIPANTS

Thirteen subjects undergoing rehabilitation after severe TBI.

OUTCOME MEASURES

Two assessments were performed, 2 to 6 weeks apart that included the following: postural sway in three stance conditions; temporal and spatial parameters of walking; functional assessments of walking, standing up, reaching while standing, and stair climbing.

RESULTS

There were significant reductions in postural sway in all stance conditions (p < .05) and significant increases in velocity of walking (p < .05), stride length (p < .01), and left and right step lengths (p < .01). Performance on all functional tasks improved (p < .05) except for functional reach. There were no significant correlations between changes in postural sway and changes in walking parameters or functional assessments.

CONCLUSION

This study demonstrated significant improvements in postural sway, walking parameters, and functional tasks during a relatively short period of rehabilitation after severe TBI. Improvements in standing balance appear to be independent of improvements in walking performance, suggesting that different mechanisms underlie improved control of these tasks.

Predictors of prognosis and risk of acute renal failure in patients with Rocky Mountain spotted fever

BACKGROUND

Acute renal failure has long been associated with severe Rocky Mountain spotted fever (RMSF). Despite many descriptions of the protean manifestations of this disease, relatively little is known concerning the risk factors for acute renal failure. Only a few studies have examined the outcome of patients infected with Rickettsia rickettsii who develop renal insufficiency, and these studies had methodological problems.

OBJECTIVE

To study the incidence, risk factors, and outcomes of acute renal failure in a large group of hospitalized patients with definite or probable RMSF.

METHODS

The clinical records of 114 patients with definite or probable RMSF were retrospectively reviewed to identify clinical and biochemical abnormalities at the time of admission that were associated with the development of acute renal failure and subsequent mortality. Renal failure was defined as a serum creatinine (Cr) above 2 mg/dL. Logistic regression was used to study the association between these variables and the outcomes during hospitalization: death and the development of acute renal failure.

RESULTS

The mortality rate in this series was 14%; 19% of the patients developed acute renal failure. The development of acute renal failure increased the odds ratio (OR) of dying by a factor of 17 (P = 0.001). Factors at the time of hospitalization that were associated at a univariate level with subsequent mortality included elevated serum Cr, increased age, increased level of AST, increased level of bilirubin, decreased serum sodium and platelet count, the presence of neurological involvement, and being male. Both the presence of neurological involvement and an elevated serum Cr at presentation were independently associated with increased mortality by multivariate analysis. Three patients developed acute renal failure that required hemodialysis, and only 1 of these 3 patients survived; he was ultimately discharged with a normal serum Cr. Factors at presentation that were associated with the development of acute renal failure included increased bilirubin, increasing age, thrombocytopenia, and the presence of neurological involvement. Both age and decreased platelet count at presentation were independently associated with the development of acute renal failure by multivariate analysis.

CONCLUSION

Acute renal failure was a frequent complication of RMSF in this series of patients from a tertiary referral medical center. The presence of acute renal failure was strongly associated with death. Clinical and biochemical variables are useful in predicting which patients will develop acute renal failure.

Identification of an immunoreactive glycoprotein in the urine of sarcoma patients

Tumor-associated antigens (TAA) can be detected in the urine of sarcoma patients by a variety of assays. This study was designed to correlate antigen activity in three assays: complement fixation assay (CFA), enzyme-linked immunosorbent assay (ELISA), and Western blot (WB). This study identifies the antibody class responsible for TAA identification in these assays and characterizes the nature of the antigen. One hundred eighty-nine urine samples from eight sarcoma patients with known levels of TAA in CFA were tested in ELISA and WB. Allogeneic anti-TAA containing sera (1 degree antibody) from a sarcoma patient was reacted with urine samples followed by detection with alkaline phosphatase-linked goat anti-human IgG and IgM (2 degree antibody in both assays). Reactivity in CFA correlated to IgM reactivity in ELISA and WB (chi 2 test, P less than 0.001). No correlation was found to IgG reactivity in either assay. Reactivity in WB vs ELISA was also highly correlated for IgM (P less than 0.001). TAA was visualized in WB as a distinct pattern of repeating bands, with most bands being detected in the range 30,000-60,000 Da. The separation between bands approximated 2500-3000 Da, suggesting a molecule composed of repeating subunits. This study suggests that the antigen is glycoprotein in nature, and that the detecting antibody is of the IgM class.

Spectrin plus band 4.1 cross-link actin. Regulation by micromolar calcium

A low-salt extract prepared from human erythrocyte membranes forms a solid gel when purified rabbit muscle G- or F-actin is added to it to give a concentration of approximately 1 mg/ml. This extract contains spectrin, actin, band 4.1, band 4.9, hemoglobin, and several minor components. Pellets obtained by centrifugation of the gelled material at 43,000 g for 10 min contain spectrin, actin, band 4.1, and band 4.9. Although extracts that are diluted severalfold do not gel when actin is added to them, the viscosity of the mixtures increases dramatically over that of G-actin alone, extract alone, or F-actin alone at equivalent concentrations. Heat-denatured extract is completely inactive. Under conditions of physiological ionic strength and pH, information of this supramolecular structure is inhibited by raising the free calcium ion concentration to micromolar levels. Low-salt extracts prepared by initial extraction at 37 degrees C (and stored at 0 degree C) gel after actin is added to them only when warmed, whereas extracts prepared by extraction at 0 degree C are active on ice as well as after warming. Preincubation of the 37 degrees C low-salt extract under conditions that favor conversion of spectrin dimer to tetramer greatly enhances gelation activity at 0 degree C. Conversely, preincubation of the 0 degree C low-salt extract under conditions that favor conversion of spectrin tetramer to dimer greatly diminishes gelation activity at 0 degree C. Spectrin dimers or tetramers are purified from the 37 dgrees or 0 degree C low-salt extract by gel filtration at 4 degrees C over Sepharose 4B. The addition of actin to either purified spectrin dimer (at 32 degrees C) or tetramer (at 0 degree C or 32 degrees C) results in relatively small increases in viscosity, whereas the addition of actin to a high-molecular-weight complex (HMW complex) containing spectrin, actin, band 4.1, and band 4.9 results in dramatic, calcium-sensitive increases in viscosity. These viscosities are comparable to those obtained with the 37 degrees or 0 degree C low-salt extracts. The addition of purified band 4.1 to either purified spectrin dimer (at 32 degrees C) or purified spectrin tetramer (at 0 degree C) plus actin results in large increases in viscosity similar to those observed for the HMW complex and the crude extract, which is in agreement with a recent report by E. Ungewickell, P. M. Bennett, R. Calvert, V. Ohanian, and W. B. Gratzer. 1979 Nature (Lond.) 280:811-814. We suggest that this spectrin-actin-band 4.1 gel represents a major structural component of the erythrocyte cytoskeleton.

Lateral mobility of human erythrocyte integral membrane proteins

Fluorescein isothiocyanate-labelled integral membrane proteins are mobile in the membranes of human erythrocytes that have fused (and haemolysed) by Sendai virus or polyethylene glycol. Minimum diffusion coefficients are of the order of 10(-11) cm2 s-1 at 37 degrees C. This mobility is reduced several-fold at room temperature, not detected at 0 degrees C, and is significantly greater in fresh than in aged blood. Mobility was assessed by observing the spread of fluorescence on labelled cells which had been fused with unlabelled cells; neither intramembrane particle aggregation nor spectrin release occurred during this process.