Occult myocardial injury is prevalent amongst elderly patients in the hospital-at-home setting. A retrospective analysis of 213 patients

Background

Hospital-at-Home (HAH) is a valid alternative for in-hospital stay for a wide variety of clinical indications. Occult myocardial injury, associated with acute illness, mainly occurs in patients with a background of non-obstructive coronary disease. The aim of this study was to describe the prevalence of this phenomenon in our HAH population.

Methods

A retrospective description and analysis of data collected for patients admitted to the Sheba beyond's HAH services during 14 months.

Results

During a period of 14 months (7/10/21-6/12/22), blood troponin measurements were available for 213 patients (median age 78 years, 52% males) hospitalized mainly for infectious causes. The median HS (highly sensitive) troponin level was 7.7 ng/L (IQR = 13.2 ng/L) (the normal upper limit is 12 ng/L) with 31% of all patients demonstrating an abnormally increased troponin level (68/213). Of all patients, 64% had a background diagnosis of a cardiovascular disease (138/213), of whom, 49% had abnormal HS troponin levels (68/138). No patient suffered from acute cardiac function deterioration and no patient died during their hospital-at-home stay.

Conclusion

The prevalence of occult myocardial injury amongst elderly patients admitted to hospital-at-home stay for diagnoses other than myocardial infarction is relatively high but it is not associated with worse short-term clinical outcomes.

POS0784 LOW COMPLEMENT LEVELS ARE ASSOCIATED WITH HIGHER MORTALITY IN HOSPITALIZED PATIENTS WITH POSITIVE ANTIPHOSPHOLIPID ANTIBODIES

Background

Antiphospholipid Syndrome is an autoimmune disease characterized by increased risk for vascular thrombosis (arterial and/or venous) thrombosis and/or pregnancy morbidity in the presence of antiphospholipid antibodies. The mechanisms by which aPLs induce thrombosis are unclear; several have been suggested, among them complement activation.(1-2) The complement system is a system of enzymes and regulatory proteins of the innate immune system that play a crucial role in the inflammatory response to various pathogenic stimuli. The complement and coagulation pathways are interconnected, and expanding evidence indicates that complement may be activated in patients with antiphospholipid syndrome (3-5).

Objectives

Our study was intended to better characterize the complicated relations between antiphospholipid antibodies and complement activation among hospitalized patients with antiphospholipid syndrome and its impact on short- and long-term prognosis

Methods

A retrospective cohort studies. Clinical and prognostic data of hospitalized patients with antiphospholipid syndrome and a measurement of complement levels (C3 or C4) were obtained. Rates of long-term mortality, one-year mortality, deep vein thrombosis (DVT), and pulmonary emboli (PE) were compared between patients with low complement levels and patients with normal complement levels. Low complement was defined as C3 < 90 mg/dl or C4 < 10 mg/dl. A multivariate analysis was performed to control for Anticardiolipin levels, β₂ macroglobulin levels and RVVT ratio.

Results

Complete data was available for 6,599 patients, of which 712 (11%) had low complement levels. The median age of the cohort was 47.7, and most of the patients were females (56%). Patients with low complement levels had significantly higher mortality rates 30% vs. 18%, p < 0.001 for long-term mortality (Figure 1) and 15% vs. 5%, p < 0.001 for 1 year mortality when compared to patients with normal complement levels. DVT and PE rates were similar (4% vs 3.8%, P = 0.78 and 4% vs 2.4%, P = 0.13 respectively). Results of the multivariate analysis (Table 1) were consistent and showed that patients with low complement levels had 111% higher mortality rates (CI 1.52-2.90, P < 0.001).

Table 1.

Multivariate Analysis for long term mortality

Multivariate AnalysisOR (CI)pLow Complement2.11 [1.52, 2.90]<0.001Anticardiolipin IGG1.00 [1.00, 1.01]0.243Anticardiolipin IGM0.99 [0.98, 1.00]0.084β₂ IGM1.01 [1.00, 1.01]0.017β₂ IGG1.00 [0.99, 1.00]0.663RVVT Ratio0.99 [0.63, 1.52]0.954Figure 1.

Cumulative 10-Year survival

Conclusion

In hospitalized patients with high aPLs, low complement levels are associated with significantly higher mortality rates. This finding is in correlation with recent literature, suggesting an important role for complement activation in APS.

References

[1]Chaturvedi S, Brodsky RA, McCrae KR. Complement in the pathophysiology of the antiphospholipid syndrome. Front Immunol. 2019 Mar 14;10:449.

[2]Bu C, Gao L, Xie W, Zhang J, He Y, Cai G, et al. beta2-glycoprotein i is a cofactor for tissue plasminogen activator-mediated plasminogen activation. Arthritis Rheum. 2009 Feb;60(2):559–568.

[3]Tedesco F, Borghi MO, Gerosa M, Chighizola CB, Macor P, Lonati PA, et al. Pathogenic role of complement in antiphospholipid syndrome and therapeutic implications. Front Immunol. 2018 Jun 19;9:1388.

[4]Oku K, Nakamura H, Kono M, Ohmura K, Kato M, Bohgaki T, et al. Complement and thrombosis in the antiphospholipid syndrome. Autoimmun Rev. 2016 Oct;15(10):1001–1004.

[5]Salmon JE, Girardi G, Holers VM. Complement activation as a mediator of antiphospholipid antibody induced pregnancy loss and thrombosis. Ann Rheum Dis. 2002 Nov;61 Suppl 2:ii46–50.

Disclosure of Interests

None declared

Low ALT values amongst hospitalized patients are associated with increased risk of hypoglycemia and overall mortality: a retrospective, big-data analysis of 51 831 patients

BACKGROUND

Sarcopenia and frailty influence clinical patients' outcomes. Low alanine aminotransferase (ALT) serum activity is a surrogate marker for sarcopenia and frailty. In-hospital hypoglycemia is associated, also with worse clinical outcomes.

AIM

We evaluated the association between low ALT, risk of in-hospital hypoglycemia and subsequent mortality.

DESIGN

This was a retrospective cohort analysis.

METHODS

We included patients hospitalized in a tertiary hospital between 2007 and 2019. Patients' data were retrieved from their electronic medical records.

RESULTS

The cohort included 51 831 patients (average age 70.88). The rate of hypoglycemia was 10.8% (amongst diabetics 19.4% whereas in non-diabetics 8.3%). The rate of hypoglycemia was higher amongst patients with ALT < 10 IU/l in the whole cohort (14.3% vs. 10.4%, P < 0.001) as well as amongst diabetics (24.6% vs. 18.8%, P < 0.001). Both the overall and in-hospital mortality were higher in the low ALT group (57.7% vs. 39.1% P < 0.001 and 4.3% vs. 3.2%, P < 0.001). A propensity score matching, after which a regression model was performed, showed that patients with ALT levels < 10 IU/l had higher risk of overall mortality (HR = 1.21, CI 1.13-1.29, P < 0.001).

CONCLUSIONS

Low ALT values amongst hospitalized patients are associated with increased risk of in-hospital hypoglycemia and overall mortality.

“Staying at Home”: A pivotal trial of telemedicine-based internal medicine hospitalization at a nursing home

Background

In-hospital stay of acutely ill elderlies could be reduced by increasing the availability of community-based hospitalizations. The feasibility of remotely managing these patients by specialized internists, without leaving their nursing homes should be sought. In the current pivotal study, we aimed to evaluate the aforementioned model.

Methods

This was a prospective, open-label study at a tertiary medical center and a nursing home. The study aimed at comparing clinical outcomes of patients hospitalized in each location.

Results

Over a period of 5.5 months, we recruited 18 patients designated for hospitalization, meeting our inclusion criteria to either in-hospital stay or staying in their nursing home and treated by means of telemedicine from our tertiary medical center. The mean age was 85.3 years. Out of 114 hospitalization days, 44 days (48%) were at the nursing home. No significant difference was noted in terms of age, gender, and length of stay between the patients who were hospitalized in either location. In almost all cases, diagnosis changed during hospitalization. Three patients died during the study, all included in the in-hospital group. No safety breaching events happened in the nursing home-hospitalization group.

Conclusions

Remote, telemedicine-based hospitalization of nursing home-dwelling elderlies is safe and feasible, potentially reducing the length of in-hospital stay by almost 50%. Larger studies in this realm are warranted.

Pulmonary hypertension is associated with systemic arterial hypertension among patients with normal diastolic function

Introduction

The association of pulmonary and systemic arterial hypertension is believed to be mediated through hypertensive left heart disease. The purpose of the current study was to investigate whether pulmonary arterial hypertension (PAH) is associated with systemic arterial hypertension among patients with apparently normal left heart diastolic function.

Methods

Consecutive patients who had echocardiographic evaluation between 2007 and 2019. Patients with disease states that are known to be associated with PAH including diastolic dysfunction were excluded from the analysis. Estimated right ventricular systolic pressure (RVSP) was extracted for all patients from the echocardiographic reports. PAH was defined as estimated RVSP &gt;40 mmHg. Multivariate logistic regression models were applied.

Results

Final study population included 25,916 patients with a median age of 59 (IQR 44–69), of whom 12,501 (48%) were male and 13,265 (51%) had systemic arterial hypertension. Compared with normotensive patients, hypertensive patients were 3.2 times more likely to have PAH (95% CI; 2.91–3.53, p&lt;0.001). A multivariate model adjusted for clinical and echocardiographic parameters that are known to be associated with PAH demonstrated that hypertensive patients are almost 3 times more likely to have PAH (95% CI 2.45–3.15, p&lt;0.001). The association was significant in multiple subgroups but was more significant among women compared with men (OR 3.1 vs. 2.4, p for interaction &lt;0.001).

Conclusions

PAH is associated with systemic arterial hypertension irrespective of left heart disease. The association is more pronounced among women.

Funding Acknowledgement

Type of funding sources: None. Estimated RVSP &gt;40 by Systolic BP

Low ALT levels are associated with poor outcomes in acute coronary syndrome patients admitted to the intensive cardiac care unit

Background

Frailty is an under recognized and important entity that bears worse prognosis.

Purpose

Although low serum alanine aminotransferase (ALT) can serve as a novel marker of frailty, its use was never assessed in acute coronary syndrome (ACS) patients.

Methods

A retrospective analysis of hospitalized ACS patients in the intensive cardiac care unit (ICCU) between 1/5/2011 and 1/12/2020 at a single tertiary medical center.

Results

The study included 3956 patients after excluding patients with ALT &gt;40 IU/L, cirrhosis and missing data, followed for a median duration of 47 months (IQR 20–77). Patients were stratified into two groups based on their first ALT measurement within the index hospitalization: low-normal ALT group (ALT ≤10 IU/L) vs. high-normal ALT group (ALT &gt;10 IU/L). Patients with ALT≤10 IU/L were older (mean age 71 vs. 65, P&lt;0.001), presented more frequently with non-ST elevation myocardial infarction (66.4% vs. 53.2%, P&lt;0.001), had higher rates of comorbidities at baseline, and had a lower Norton score upon admission. Hospitalization length was longer in the low-normal ALT group (P&lt;0.001). Although the in-hospital mortality rate was similar between the groups (0.9% vs. 0.7%, P=0.99), long-term mortality was significantly higher in the low-normal ALT group (22.7% vs. 7.9%, P&lt;0.001). In a multivariate regression model ALT ≤10 IU/l was associated with increased mortality (HR 2.1, 95% CI 1.46–3).

Conclusion

Lower serum ALT is associated with worse outcomes in ACS patients admitted to the ICCU.

Funding Acknowledgement

Type of funding sources: None. 5-year survival according to baseline ALForest plot of variables associated with

Reducing drug prescription errors and adverse drug events by application of a probabilistic, machine-learning based clinical decision support system in an inpatient setting

BACKGROUND

Drug prescription errors are made, worldwide, on a daily basis, resulting in a high burden of morbidity and mortality. Existing rule-based systems for prevention of such errors are unsuccessful and associated with substantial burden of false alerts.

OBJECTIVE

In this prospective study, we evaluated the accuracy, validity, and clinical usefulness of medication error alerts generated by a novel system using outlier detection screening algorithms, used on top of a legacy standard system, in a real-life inpatient setting.

MATERIALS AND METHODS

We integrated a novel outlier system into an existing electronic medical record system, in a single medical ward in a tertiary medical center. The system monitored all drug prescriptions written during 16 months. The department's staff assessed all alerts for accuracy, clinical validity, and usefulness. We recorded all physician's real-time responses to alerts generated.

RESULTS

The alert burden generated by the system was low, with alerts generated for 0.4% of all medication orders. Sixty percent of the alerts were flagged after the medication was already dispensed following changes in patients' status which necessitated medication changes (eg, changes in vital signs). Eighty-five percent of the alerts were confirmed clinically valid, and 80% were considered clinically useful. Forty-three percent of the alerts caused changes in subsequent medical orders.

CONCLUSION

A clinical decision support system that used a probabilistic, machine-learning approach based on statistically derived outliers to detect medication errors generated clinically useful alerts. The system had high accuracy, low alert burden and low false-positive rate, and led to changes in subsequent orders.

Baseline low ALT activity is associated with increased long-term mortality after COPD exacerbations

BACKGROUND

COPD exacerbations have negative impact on patients' survival. Several risk factors for grave outcomes of such exacerbations have been descried. Muscle dysfunction and mass loss were shown to impact negatively on prognosis and survival. Low activity of the enzyme ALT (Alanine amino-transferase) in the blood is a known indicator for sarcopenia and frailty, however, no previous studies addressed the association of low ALT amongst patients hospitalized due to COPD exacerbation and long-term survival.

METHODS

This is a historic prospective cohort study of patients hospitalized due to acute COPD exacerbation.

RESULTS

Included were 232 consecutive COPD exacerbation patients. The median time of follow-up was 34.9 months (IQR 23.13-41.73 months). During this period 104 (44.8%) patients died. All patients were grouped to quartiles according to blood ALT levels (after exclusion of cases considered to have hepatic tissue damage (ALT > 40 IU)). The risk of long-term mortality increased, in a statistically significant manner, amongst patients with low ALT values: the median survival of patients with ALT < 11 IU was 18.5 months only while the median survival for the rest of the study group was not reached. For ALT < 11 IU; 12-16 IU; 17-20 IU and > 21 IU the mortality rates were 69%; 40.9%; 36.3 and 25% respectively (p <  0.001 for comparison of lower quartile with upper three quartiles). The crude hazard ratio for mortality amongst patients with ALT levels lower than 11 IU was 2.37 (95% CI; 1.6-3.5). This increased risk of mortality remained significant after adjustment for age, weight, creatinine, albumin concentration and cardiovascular diseases (HR = 1.83; 95% CI 1.08-3.1, p <  0.05).

CONCLUSIONS

Low ALT values, a biomarker of sarcopenia and frailty, are associated with poor long-term survival amongst patients hospitalized due to COPD exacerbation.

L3 skeletal muscle index (L3SMI) is a surrogate marker of sarcopenia and frailty in non-small cell lung cancer patients

Background: Non-small cell lung cancer (NSCLC) is a common and highly lethal disease. As advanced treatment modalities are being developed, improved prognostication methods are sought. L3 skeletal muscle index (L3SMI) and alanine aminotransferase (ALT) levels are accepted surrogate markers of sarcopenia and related frailty. We aimed to evaluate the potential association of these markers with NSCLC patients’ survival.

Methods: A retrospective, single-center study of an NSCLC patients’ cohort. L3SMI was calculated based on skeletal muscle area on computed tomography scans at the level of the L3 vertebra. Clinical data were extracted from clinical charts.

Results: A total of 140 patients (56.4% males, median age 66 [range 37–86]) were included in this study, 32% were diagnosed at stage 3 and 45% at stage 4. During the follow-up duration (median of 1.9 years; range 1 month to 6.4 years), 102 patients (72.8%) died. Patients’ characteristics that were found to be associated with increased mortality were performance status, albumin and tumor stage at diagnosis. Sarcopenia, defined as low L3SMI (lower than 41 cm²/m² for women and lower than 53 cm²/m² for men) was significantly associated with higher risk of mortality compared with patients with normal L3SMI values (77.2%, vs 64.6%, p=0.013) in univariate analysis, but not in a multiple regression analysis.

Conclusion: Low L3SMI could serve as a surrogate marker for sarcopenia and frailty and, as such, facilitate the prognostication process of NSCLC patients.

Sodium phosphate enemas do not worsen renal function among hospitalized patients with mild to moderate renal failure: a matched, case-control study

BACKGROUND

Sodium phosphate enemas (SPEs) are widely used among hospitalized patients despite their potential to worsen renal failure.

AIM

We decided to assess the extent to which this side effect is clinically relevant.

DESIGN

We conducted a matched case-control, retrospective study in a cohort of hospitalized patients.

METHODS

Patients treated and untreated with SPEs were matched for age, gender, baseline creatinine, usage of certain medications and several background diagnoses. Three groups of matched patients (whole study cohort, patients with baseline creatinine > 1.5 mg/dl and those with baseline creatinine > 2 mg/dl) were compared with regards to their creatinine and blood electrolyte concentrations during 3 consecutive hospitalization days after SPE application.

RESULTS

Four hundred and twelve patients were included in this study of which 206 were treated by single SPEs. Exact matching was done for the whole study cohort, for 108 patients with baseline creatinine > 1.5 mg/dl and for 58 patients with baseline creatinine > 2 mg/dl. During 3 consecutive days after SPEs, the maximal blood concentrations of creatinine, phosphor and potassium did not differ significantly between treated patients and matched controls, in all three patients' groups.

CONCLUSION

Application of SPEs neither seem to worsen mild to moderate renal failure, nor are associated with hyperphosphatemia or hyperkalemia in patients hospitalized in internal medicine departments.

Changing Metrics of Organ Procurement Organization Performance in Order to Increase Organ Donation Rates in the United States

The shortage of deceased-donor organs is compounded by donation metrics that fail to account for the total pool of possible donors, leading to ambiguous donor statistics. We sought to assess potential metrics of organ procurement organizations (OPOs) utilizing data from the Nationwide Inpatient Sample (NIS) from 2009-2012 and State Inpatient Databases (SIDs) from 2008-2014. A possible donor was defined as a ventilated inpatient death ≤75 years of age, without multi-organ system failure, sepsis, or cancer, whose cause of death was consistent with organ donation. These estimates were compared to patient-level data from chart review from two large OPOs. Among 2,907,658 inpatient deaths from 2009-2012, 96,028 (3.3%) were a "possible deceased-organ donor." The two proposed metrics of OPO performance were: (1) donation percentage (percentage of possible deceased-donors who become actual donors; range: 20.0-57.0%); and (2) organs transplanted per possible donor (range: 0.52-1.74). These metrics allow for comparisons of OPO performance and geographic-level donation rates, and identify areas in greatest need of interventions to improve donation rates. We demonstrate that administrative data can be used to identify possible deceased donors in the US and could be a data source for CMS to implement new OPO performance metrics in a standardized fashion.

Knee osteoarthritis, degenerative meniscal lesion and osteonecrosis of the knee: Can a simple gait test direct us to a better clinical diagnosis

INTRODUCTION

The purpose of the current study was to compare the gait patterns in patients with three differing knee pathologies - knee osteoarthritis (OA), degenerative meniscal lesion (DML) and spontaneous osteonecrosis of the knee (SONK) and a group of healthy controls.

HYPOTHESIS

A simple gait test will detect differences between different knee pathologies.

MATERIAL AND METHODS

Forty-seven patients with bilateral knee OA, 47 patients with DML, 28 patients with SONK and 27 healthy controls were included in this analysis. Patients underwent a spatiotemporal gait assessment and were asked to complete the Western Ontario and McMaster University (WOMAC) Index and the Short-Form (SF)-36 Health Survey. ANOVA tests, followed by Bonferroni multiple comparison tests and the Chi² tests were performed for continuous and categorical variables, respectively.

RESULTS

Significant differences were found for all gait measures and clinical questionnaires between healthy controls and all knee conditions. Patients with SONK differed from patients with bilateral knee OA and DML in all gait measures and clinical questionnaires, except for WOMAC subscales. There were no significant differences between patients with bilateral knee OA and patients with DML. Symmetry was also examined and revealed asymmetry in some gait parameters in patients with SONK and DML.

DISCUSSION

Based on the differences in gait parameters that were found in the current study, adding an objective functional spatiotemporal gait test may assist in the diagnostic process of knee pathologies.

TYPE OF STUDY

Case Control study Level III.

Low ALT Levels Independently Associated with 22-Year All-Cause Mortality Among Coronary Heart Disease Patients

BACKGROUND

Low alanine aminotransferase (ALT) blood levels are known to be associated with frailty and increased risk of long-term mortality in certain populations. However, the contribution of this marker to long-term outcome has not been assessed in patients with chronic coronary heart disease.

OBJECTIVE

The aim of the current study was to assess the association between low ALT values and long-term, 22.8-year, all-cause mortality in this population.

PARTICIPANTS

We examined the association of low ALT (<17 IU/l) with long-term all-cause mortality in the Bezafibrate Infarction Prevention (BIP) Registry population.

KEY RESULTS

Appropriate laboratory and survival data were available for 6,575 patients, without known liver pathology, included in the BIP registry, with a median follow-up period of 22.8 years. The cumulative probability of all-cause mortality was significantly higher in the low ALT group compared with patients with higher ALT levels (65.6 % vs. 58.4 %; log-rank p < 0.001). Consistently, multivariate analysis, adjusted for multiple established predictors of mortality in this population, demonstrated that low ALT is independently associated with 11 % greater long-term (22.8 years) mortality risk [HR 1.11 (95 % confidence interval: 1.03-1.19; adjusted p < 0.01)].

CONCLUSIONS

Low ALT levels are associated with increased long-term mortality among middle-aged patients with stable coronary heart disease. This association remained statistically significant after adjustment for other well-established risk factors for mortality in this population.

Decreased dopaminergic treatment of hospitalized Parkinson's disease patients during infectious diseases is associated with poor outcomes

A retrospective analysis of consecutive Parkinson's disease (PD) patients hospitalized in internal medicine wards during the years 2008 to 2013 due to infectious disease was performed. PD patients are prone to infections, often leading to hospitalization in internal medicine wards. We observed that during these hospitalizations, chronic anti-Parkinson's medications are frequently overlooked and withdrawn, their reintroduction is delayed and dosages are decreased. Only patients on chronic therapy with at least one anti-Parkinson's medication were included in this study. Multivariate analyses established the association between medication dose reductions on short-term clinical outcomes, including in-hospital mortality and change in discharge destination. Medical records from 528 PD patients were analyzed and 430 were excluded. Of the 98 included, 53 had pneumonia and 58 had urinary tract infections. The overall in-hospital mortality rate was 11.2%. 56.1% of patients' dopaminergic medications were decreased in dose upon admission (22.5% mean decrease in levodopa equivalent daily dose [LEDD]; p<0.001). Both absolute and relative LEDD reductions were associated with significantly increased in-hospital mortality (mean reduction of 394.5 mg versus 188.4 mg; p=0.035 by analysis of variance adjusted to age, sex and renal function) and was also associated with worse discharge destination relative to original place of arrival (mean reduction of 377.8 mg versus 150.7 mg; p=0.014). Decreased dopaminergic medication dosing upon admission of PD patients due to infection is widespread and potentially associated with worse clinical outcomes.

Low ALT blood levels predict long-term all-cause mortality among adults. A historical prospective cohort study

BACKGROUND

Increased blood levels of alanine amino transferase (ALT, also known as SGPT; serum glutamic pyruvic transaminase) serve as a marker of liver injury by various mechanisms. Less is known about the clinical implications associated with low-normal ALT levels. Previous studies showed low ALT levels to be associated with poor long-term outcomes among elderlies, serving as a biomarker for increased incidence of frailty and subsequent risk of mortality. However, it has not been determined yet whether low-normal ALT values might be predictive of frailty and mortality in younger, middle-aged adults.

METHODS

We conducted a historical prospective cohort analysis.

RESULTS

A total of 23,506 adults with ALT levels within the normal range, at the mean age of 48 ± 11 years, participating in an annual screening program for preventive medicine, were followed-up for a median period of 8.5 years during which 638 died. Low-normal ALT values (serum ALT activity <17IU/L) were found to be predictive for increased risk of all-cause mortality (HR=1.6; 95% CI 1.34-1.92; p<0.001). Statistically significant correlation was demonstrated even after applying a multifactorial model correction for age, gender, eGFR, low albumin, arterial hypertension, diabetes mellitus and ischemic heart disease.

CONCLUSIONS

We suggest that low-normal ALT values may serve as an independent predictive marker for increased long-term mortality in middle-aged adults.

Novel classification of knee osteoarthritis severity based on spatiotemporal gait analysis

OBJECTIVE

To describe a novel classification method for knee osteoarthritis (OA) based on spatiotemporal gait analysis.

METHODS

Gait analysis was initially performed on 2911 knee OA patients. Females and males were analyzed separately because of the influence of body height on spatiotemporal parameters. The analysis included the three stages of clustering, classification and clinical validation. Clustering of gait analysis to four groups was applied using the kmeans method. Two-thirds of the patients were used to create a simplified classification tree algorithm, and the model's accuracy was validated by the remaining one-third. Clinical validation of the classification method was done by the short form 36 Health Survey (SF-36) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires.

RESULTS

The clustering algorithm divided the data into four groups according to severity of gait difficulties. The classification tree algorithm used stride length and cadence as predicting variables for classification. The correct classification accuracy was 89.5%, and 90.8% for females and males, respectively. Clinical data and number of total joint replacements correlated well with severity group assignment. For example, the percentages of total knee replacement (TKR) within 1 year after gait analysis for females were 1.4%, 2.8%, 4.1% and 8.2% for knee OA gait grades 1-4, respectively. Radiographic grading by Kellgren and Lawrence was found to be associated with the gait analysis grading system.

CONCLUSIONS

Spatiotemporal gait analysis objectively classifies patients with knee OA according to disease severity. That method correlates with radiographic evaluation, the level of pain, function, number of TKR.

A week-by-week analysis of the low-risk criteria for serious bacterial infection in febrile neonates

OBJECTIVE

To examine the reliability of "low-risk" criteria (LRC) to exclude serious bacterial infection (SBI) in febrile neonates (< or =28 days), according to age in weeks.

DESIGN

Epidemiological and clinical data and final diagnosis of all febrile neonates presenting to the emergency room from June 1997 to May 2006 were reviewed. Neonates who fulfilled specific LRC for the presence of SBI were classified as LRC+. The prevalence of SBI and the percentage of LRC+ neonates who had SBI were calculated for each of the first 4 weeks of life.

RESULTS

A total of 449 neonates were evaluated. Eighty-seven (19.4%) neonates had an SBI. The prevalence of SBI among infants 3-7, 8-14, 15-21 and 22-28 days of age was 21.6%, 26.1%, 17.9% and 12.1%, respectively (p = 0.007 for linear trend after second week of life). Of the 226 LRC+ neonates, 14 (6.2%) had an SBI, including one case of bacteraemia and meningitis and 13 cases of urinary tract infection (UTI). The negative predictive value (NPV) of the LRC for SBI was 93.8% (95% CI 90.1% to 96.4%). The prevalence of SBI among LRC+ infants 3-7, 8-14, 15-21 and 22-28 days of age was similar, with rates of 15%, 6.3%, 3.0% and 6.7%, respectively.

CONCLUSION

LRC are not sufficiently reliable to exclude the presence of SBI, including bacteraemia and meningitis in febrile neonates of all ages. All febrile neonates should therefore be hospitalised, undergo a full "sepsis evaluation" and receive empirical intravenous antibiotic therapy.

The AlnB protein of the bioemulsan alasan is a peroxiredoxin

The bioemulsifier of Acinetobacter radioresistens KA53, referred to as alasan, is a high molecular weight complex of a polysaccharide and three proteins (AlnA, AlnB and AlnC). AlnA has previously been shown to be an OmpA-like protein that is largely responsible for the emulsifying activity of alasan. To further elucidate the nature of alasan, the gene coding for AlnB was cloned, sequenced and overexpressed in Escherichia coli. The overall 561 bp sequence of the hypothetical AlnB showed strong homology, including all conserved regions and residues known to be essential for enzymatic activity, to the ubiquitous family of thiol-specific antioxidant enzymes known as peroxiredoxins. Transgenic E. coli overexpressing AlnB exhibited increased resistance to cumene hydroperoxide both in liquid culture and on agar medium. Recombinant AlnB had no emulsifying activity but stabilized oil-in-water emulsion generated by AlnA.

Icm/dot-dependent upregulation of phagocytosis by Legionella pneumophila

Legionella pneumophila is the causative agent of Legionnaires' disease, a severe pneumonia. Dependent on the icm/dot loci, L. pneumophila survives and replicates in macrophages and amoebae within a specialized phagosome that does not fuse with lysosomes. Here, we report that phagocytosis of wild-type L. pneumophila is more efficient than uptake of icm/dot mutants. Compared with the wild-type strain JR32, about 10 times fewer icm/dot mutant bacteria were recovered from HL-60 macrophages in a gentamicin protection assay. The defect in phagocytosis of the mutants could be complemented by supplying the corresponding genes on a plasmid. Using fluorescence microscopy and green fluorescent protein (GFP)-expressing strains, 10-20 times fewer icm/dot mutant bacteria were found to be internalized by HL-60 cells and human monocyte-derived macrophages (HMMPhi). Compared with icm/dot mutants, wild-type L. pneumophila infected two to three times more macrophages and yielded a population of highly infected host cells (15-70 bacteria per macrophage) that was not observed with icm/dot mutant strains. Wild-type and icmT mutant bacteria were found to adhere similarly and compete for binding to HMMPhi. In addition, wild-type L. pneumophila was also phagocytosed more efficiently by Acanthamoeba castellanii, indicating that the process is independent of adherence receptor(s). Wild-type L. pneumophila enhanced phagocytosis of an icmT mutant strain in a synchronous co-infection, suggesting that increased phagocytosis results from (a) secreted effector(s) acting in trans.

Involvement of actin filaments and integrins in the binding step in collagen phagocytosis by human fibroblasts

In physiological conditions, collagen degradation by fibroblasts occurs primarily via phagocytosis, an intracellular pathway that is thought to require collagen receptors and actin assembly for fibril internalization and degradation. Currently it is unclear which specific steps of collagen phagocytosis in fibroblasts involve actin filament assembly. As studies of phagocytosis in fibroblasts are complicated by the relatively slow rate of particle internalization compared to professional phagocytes, we have examined the role of collagen receptors and actin only in the initial collagen binding step. Prior to the binding of collagen-coated fluorescent beads by human gingival fibroblasts, a cell type that is avidly phagocytic in vitro, cells were treated with cytochalasin D (actin filament barbed-end capping) or swinholide A (actin dimer sequestering and severing) or latrunculin B (actin monomer sequestering). Bead binding and immunostaining of (alpha)(2)(beta)(1) and (alpha)(3)(beta)(1) integrin collagen receptors were measured by flow cytometry. After 1–3 hours of coincubation with beads, cytochalasin D or swinholide A eliminated actin filaments stained by rhodamine-phalloidin and inhibited collagen bead binding (reductions of 25% and 50%, respectively), possibly because of cell rounding and restricted interactions with beads. In contrast, latrunculin enhanced binding dose-dependently over controls (twofold at 1 microM) and induced the formation of brightly staining aggregates of actin and the retention of long cytoplasmic extensions. Latrunculin also reduced surface (beta)(1), (alpha)(2) and (alpha)(3) integrin staining up to 40% in bead-free and bead-loaded cells, indicating that latrunculin enhanced collagen receptor internalization. As determined by fluorescence recovery after photobleaching, latrunculin increased the mobility of surface-bound (beta)(1) integrin. The stimulatory effect of latrunculin on collagen bead binding was reduced to control levels by treatment with a (beta)(1) integrin inactivating antibody while a (beta)(1) integrin blocking antibody abrogated both bead binding and the latrunculin-induced stimulation. Immunoblotting of bead-associated proteins showed that latrunculin completely eliminated binding of (beta)-actin to collagen beads but did not affect (beta)(1) integrin binding. These data indicate that latrunculin-induced sequestration of actin monomers facilitates the disengagement of actin from (beta)(1) integrin receptors, increases collagen bead binding and enhances collagen receptor mobility. We suggest that these alterations increase the probability of adhesive bead-to-cell interactions.

Relationships between a new type IV secretion system and the icm/dot virulence system of Legionella pneumophila

We describe here a Legionella pneumophila type IV secretion system that is distinct from the previously described icm/dot system. This type IV secretion system contains 11 genes (lvh ) homologous to genes of other type IV secretion systems, arranged in a similar manner. The lvh genes were found to be located on a DNA island with a GC content higher than the L. pneumophila chromosome. In contrast to the icm/dot system that was shown to be required for intracellular growth in HL-60-derived human macrophages and Acanthamoeba castellanii, the lvh system was found to be dispensable for intracellular growth in these two hosts. The lvh system was found to be partially required for RSF1010 conjugation, a process that was previously shown to be completely dependent on several icm/dot genes. However, results obtained from analysis of double mutants in the icm/dot genes and the lvh genes revealed that lvh genes can substitute for some components of the icm/dot system for RSF1010 conjugation, but not for intracellular growth. These results indicate that components of the icm/dot system and components of the lvh type IV secretion system are able to interact with one another.

Legionella pneumophila utilizes the same genes to multiply within Acanthamoeba castellanii and human macrophages

In previous reports we described a 22-kb Legionella pneumophila chromosomal locus containing 18 genes. Thirteen of these genes (icmT, -R, -Q, -P, -O, -M, -L, -K, -E, -C, -D, -J, and -B) were found to be completely required for intracellular growth and killing of human macrophages. Three genes (icmS, -G, and -F) were found to be partially required, and two genes (lphA and tphA) were found to be dispensable for intracellular growth and killing of human macrophages. Here, we analyzed the requirement of these genes for intracellular growth in the protozoan host Acanthamoeba castellanii, a well-established important environmental host of L. pneumophila. We found that all the genes that are completely required for intracellular growth in human macrophages are also completely required for intracellular growth in A. castellanii. However, the genes that are partially required for intracellular growth in human macrophages are completely required for intracellular growth in A. castellanii. In addition, the lphA gene, which was shown to be dispensable for intracellular growth in human macrophages, is partially required for intracellular growth in A. castellanii. Our results indicate that L. pneumophila utilizes the same genes to grow intracellularly in both human macrophages and amoebae.

Intracellular multiplication and human macrophage killing by Legionella pneumophila are inhibited by conjugal components of IncQ plasmid RSF1010

Previously we have reported that Legionella pneumophila can mediate plasmid DNA transfer at a frequency of about 10(-3) transconjugants per donor and that this process is dependent on several icm genes. Here we characterize the icm-dependent conjugal ability of L. pneumophila and study its relationship to intracellular multiplication and host cell killing. We found that three icm genes and the RSF1010 mobA gene are completely required and that three icm genes and the RSF1010 mobC gene are partially required for conjugation. Conjugation occurred during lag phase and stopped when the cell number increased. Inhibition of transcription or translation in the donor had only a minor effect on conjugation frequency. These results suggest that stationary-phase bacteria contain a functional icm complex that can mediate conjugal DNA transfer and probably can initiate infection of human macrophages as well. We also found that a functional RSF1010 mobilization system inhibits intracellular multiplication and killing of human macrophages by L. pneumophila. The strongest inhibition was observed in icm insertion mutants complemented with wild-type icm genes on an RSF1010-derived plasmid. These results suggest that the conjugation substrate probably competes with the natural substrate of the L. pneumophila icm system for transfer outside the bacterial cell. We propose that the function of the L. pneumophila icm system is to transfer effector molecules to the host cell. These effector molecules may interact with components of the host cell that are involved in phagosome formation and fate.

How is the intracellular fate of the Legionella pneumophila phagosome determined?

The following pair of articles, the first by Gil Segal and Howard Shuman, and the second by James Kirby and Ralph Isberg (Trends Microbiol. 6, 256-258), explore the genetics and function of the icm/dot genes of Legionella pneumophila. This gene family is implicated in several aspects of virulence and appears to constitute components of a conjugal transfer system that has been adopted to prevent phagosome-lysosome fusion in the host cell and to mediate host cytotoxicity by pore formation. Whether these functions are natural consequences or operate in parallel remains to be discovered.

Regulation of heat-shock response in bacteria

Stress response in bacteria is essential for effective adaptation to changes in the environment, as well as to the changes in the physiological state of the bacterial culture itself. This response is mediated by global regulatory mechanisms affecting several pathways. It now appears that these regulatory mechanisms operate by transcriptional control, translational control, and proteolysis. One example to be discussed extensively is the heat-shock response. In Escherichia coli, where it has been studied initially and most extensively, the expression of the heat-shock operon is transcriptionally controlled by the employment of the heat-shock transcription factor sigma 32, that recognizes specific heat-shock promoters. Later studies indicated that in most bacteria the control of the major heat-shock genes is much more complicated, and involves additional--or alternative--control channels. These regulatory elements will be reviewed looking at the groE and dnaK operons. These operons, coding for the bacterial equivalent of Hsp10+60 and Hsp70, respectively, contain in many bacteria a conserved regulatory inverted repeat (IR = CIRCE), and are transcribed either by the vegetative sigma factor--sigma 70--or by a sigma 32-like factor. The IR functions at the DNA level as a repressor binding site and also controls the half life of the transcript. In addition, in Agrobacterium tumefaciens there also exists a system for mRNA processing that involves a temperature-controlled cleavage of the groE transcript.

Rapid genomic changes in newly synthesized amphiploids of Triticum and Aegilops. I. Changes in low-copy noncoding DNA sequences

We recently reported that allopolyploid formation in wheat was accompanied by rapid nonrandom elimination of specific low-copy, noncoding DNA sequences. These sequences occur in all diploid progenitors but are chromosome- or genome-specific at the polyploid level. To further investigate this phenomenon, we studied nine of these sequences, six chromosome-specific sequences and three genome-specific sequences, all isolated from common wheat. The various sequences were hybridized to DNA derived from nine newly synthesized amphiploids at different ploidy levels and to DNA from their parental lines. Although sequences homologous to the probes occur in all parental lines, a nonrandom loss of hybridization fragments was found at a high frequency in all amphiploids studied. In addition, a "loss/gain" of a hybridization fragment(s) was noticed in some of the amphiploids at lower frequency. Neither the type nor the frequency of changes was affected by intergenomic recombination or DNA methylation. It is suggested that rapid genomic changes culminated in a "programmed" pattern of elimination and (or) modification of specific low-copy DNA sequences following allopolyploidization. These events augmented the differentiation of homoeologous chromosomes, thus providing the physical basis for the diploid-like cytological behavior of polyploid wheat.Key words: wheat, allopolyploidy, genome evolution, chromosome- or genome-specific sequences, sequence elimination, homoeologous chromosome differentiation.

Host cell killing and bacterial conjugation require overlapping sets of genes within a 22-kb region of the Legionella pneumophila genome

A 22-kb DNA locus of Legionella pneumophila is described that contains 18 genes, 16 of which are required for macrophage killing (icm genes). In this paper two previously described icm loci were linked by the discovery of five genes located between the two loci. Four of the newly described genes are required for macrophage killing (icmMLKE) and one is dispensable. The 16 icm genes appeared to be organized as six individual genes (icmR, icmQ, icmG, icmC, icmD, and icmF), and four operons (icmTS, icmPO, icmMLKE, and icmJB). Four icm genes (icmP, icmO, icmL, and icmE) show significant sequence similarity to plasmid genes involved in conjugation, whereas the other icm genes were found not to bear any sequence similarity to database entries. We found that L. pneumophila can mediate plasmid DNA transfer at a frequency of 10(-3) to 10(-4) per donor. Strains containing null mutations in two icm genes (icmT and icmR) showed a severe reduction in conjugation frequency and macrophage killing. Strains containing an insertion in four other icm genes (icmF, icmE, icmC, and dotA) were shown to have a less severe defect in conjugation. Mutations in the other 11 icm genes had no effect on conjugation frequency. We currently do not know whether conjugation itself plays a role in macrophage killing. It is possible either that small plasmids can take advantage of an existing secretion system to be mobilized or that DNA transfer is required for human macrophage killing by L. pneumophila.

Characterization of a new region required for macrophage killing by Legionella pneumophila

In a previous study, a collection of 55 Legionella pneumophila mutants defective for macrophage killing was isolated by transposon mutagenesis. In this study, nine of these mutants that belong to the same DNA hybridization group (group 3) were characterized. A wild-type DNA fragment that covers this DNA hybridization group was cloned and sequenced. This region was found to contain six new genes (designated icmT, icmS, icmR, icmQ, icmP, and icmO), five of which contain at least one transposon insertion. No transposon insertion was found in icmS. However, this gene was found to be required for macrophage killing, since a kanamycin resistance cassette introduced into icmS by gene replacement resulted in a mutant that was attenuated for macrophage killing. A plasmid containing the DNA fragment that covers this region complements all the mutants for macrophage killing, although various levels of complementation were observed for mutants in different genes. Complementation tests were also performed with plasmids containing one or two of these genes, as well as with plasmids containing nonpolar in-frame deletions. The results from these complementation tests indicated that all six genes located in this region are needed for macrophage killing and that they are probably arranged as two transcriptional units (icmTS and icmPO) and two genes (icmR and icmQ). A region upstream of the coding sequence of several icm genes may contain a potential promoter and/or regulatory site. Homology searches show that icmP and icmO bear significant homology to the trbA and trbC genes from the Salmonella R64 plasmid, respectively. The sequences of the other four genes do not show significant homology with any entries in sequence databases.