Impact of 24/7 loading of blood culture bottles in a new automated incubator on the diagnosis of bloodstream infections.

Blood culturing (BC) remains the gold standard for bloodstream diagnosis but its workflow is slow. We aimed reducing this time by implementing a new automated incubator with a 24/7 BC workflow. With this new strategy, time to incubation was shorter (1.52 h vs 6.82 h), positivity rates were higher (10.6% vs 8.9%, p<0.05), and the number of BSI diagnostics increased (16.1% vs 13.8% patients and 2.3 vs 1.9 density episode per 1000 hospital days). Our results show that implementing automatic loading of BC bottles with a 24/7 strategy not only shortened time to diagnosis but significantly increased the BSI diagnosis rate.

The XX sex chromosome complement in mice is associated with increased spontaneous lupus compared with XY.

OBJECTIVES: Many autoimmune diseases are characterised by a female predominance. This may be caused by sex hormones, sex chromosomes or both. This report uses a transgenic mouse model to investigate how sex chromosome complement, not confounded by differences in gonadal type, might contribute to lupus pathogenesis. METHODS: Transgenic NZM2328 mice were created by deletion of the Sry gene from the Y chromosome, thereby separating genetic from gonadal sex. Survival, renal histopathology and markers of immune activation were compared in mice carrying the XX versus the XY(-) sex chromosome complement, with each genotype being ovary bearing. RESULTS: Mice with XX sex chromosome complement compared with XY(-) exhibited poorer survival rates and increased kidney pathology. Splenic T lymphocytes from XX mice demonstrated upregulated X-linked CD40 ligand expression and higher levels of activation markers ex vivo. Increased MMP, TGF and IL-13 production was found, while IL-2 was lower in XX mice. An accumulation of splenic follicular B cells and peritoneal marginal zone B cells was observed, coupled with upregulated costimulatory marker expression on B cells in XX mice. CONCLUSION: These data show that the XX sex chromosome complement, compared with XY(-), is associated with accelerated spontaneous lupus.

Estrogen treatment decreases matrix metalloproteinase (MMP)-9 in autoimmune demyelinating disease through estrogen receptor alpha (ERalpha).

Matrix metalloproteinases (MMPs) have a crucial function in migration of inflammatory cells into the central nervous system (CNS). Levels of MMP-9 are elevated in multiple sclerosis (MS) and predict the occurrence of new active lesions on magnetic resonance imaging (MRI). This translational study aims to determine whether in vivo treatment with the pregnancy hormone estriol affects MMP-9 levels from immune cells in patients with MS and mice with experimental autoimmune encephalomyelitis (EAE). Peripheral blood mononuclear cells (PBMCs) collected from three female MS patients treated with estriol and splenocytes from EAE mice treated with estriol, estrogen receptor (ER) alpha ligand, ERbeta ligand or vehicle were stimulated ex vivo and analyzed for levels of MMP-9. Markers of CNS infiltration were assessed using MRI in patients and immunohistochemistry in mice. Supernatants from PBMCs obtained during estriol treatment in female MS patients showed significantly decreased MMP-9 compared with pretreatment. Decreases in MMP-9 coincided with a decrease in enhancing lesion volume on MRI. Estriol treatment of mice with EAE reduced MMP-9 in supernatants from autoantigen-stimulated splenocytes, coinciding with decreased CNS infiltration by T cells and monocytes. Experiments with selective ER ligands showed that this effect was mediated through ERalpha. In conclusion, estriol acting through ERalpha to reduce MMP-9 from immune cells is one mechanism potentially underlying the estriol-mediated reduction in enhancing lesions in MS and inflammatory lesions in EAE.

Downregulation of monocytic differentiation via modulation of CD147 by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors.

CD147 is an activation induced glycoprotein that promotes the secretion and activation of matrix metalloproteinases (MMPs) and is upregulated during the differentiation of macrophages. Interestingly, some of the molecular functions of CD147 rely on its glycosylation status: the highly glycosylated forms of CD147 induce MMPs whereas the lowly glycosylated forms inhibit MMP activation. Statins are hydroxy-methylglutaryl coenzyme A reductase inhibitors that block the synthesis of mevalonate, thereby inhibiting all mevalonate-dependent pathways, including isoprenylation, N-glycosylation and cholesterol synthesis. In this study, we investigated the role of statins in the inhibition of macrophage differentiation and the associated process of MMP secretion through modulation of CD147. We observed that differentiation of the human monocytic cell line THP-1 to a macrophage phenotype led to upregulation of CD147 and CD14 and that this effect was inhibited by statins. At the molecular level, statins altered CD147 expression, structure and function by inhibiting isoprenylation and N-glycosylation. In addition, statins induced a shift of CD147 from its highly glycosylated form to its lowly glycosylated form. This shift in N-glycosylation status was accompanied by a decrease in the production and functional activity of MMP-2 and MMP-9. In conclusion, these findings describe a novel molecular mechanism of immune regulation by statins, making them interesting candidates for autoimmune disease therapy.

A cost effective approach to the investigation of syncope: relative merit of different diagnostic strategies.

OBJECTIVE: To compare the cost effectiveness of a conventional diagnostic work-up with that of several different diagnostic cascades for the investigation of undifferentiated syncope. DESIGN: A MEDLINE search established a weighted estimate of diagnostic yield for several diagnostic investigations. 'High-end' and 'low-end' cost estimates were calculated for these investigations based on figures from four representative Canadian tertiary care centres in four different provinces. Several diagnostic models were applied to a hypothetical cohort of 100 patients with undifferentiated syncope. RESULTS: The conventional diagnostic cascade resulted in a diagnosis in 85% of patients, at a cost per diagnosis of $467 to $959. The optimal model increased the diagnostic yield to 98.9%, at a cost of $460 to $1043 per diagnosed patient. CONCLUSION: A combination of new technology and selective use of investigations has the potential to raise diagnostic yield without appreciably increasing cost per diagnosis.

Genetics of coronary artery disease - a clinician's perspective.

Coronary artery disease (CAD) is the major cause of fatality and disability among all cardiovascular diseases (CVD). Intricate interactions of genes and environment dictate the outcomes of CAD. Technological advances in the different fields of genetics including linkage studies (LS), candidate gene studies (CGS) and genome-wide association studies (GWA studies) have augmented the knowledge of pathogenesis of CAD. LS were more successful in identifying genetic variants among monogenic disease. GWA studies were relatively popular in identification of variation in polygenic disease. Until now, GWA studies recognized about 50 loci determining around 6% of the heritability in CAD. Clinical utility of the above knowledge would result in better CAD management, but validation of the variants in native population is warranted for active adoption into the clinic. The major aim of this review is to provide an adequate perspective of our current understanding and advances of genetics in CAD.

Attenuation of corpus callosum axon myelination and remyelination in the absence of circulating sex hormones.

Sex differences in the structure and organization of the corpus callosum (CC) can be attributed to genetic, hormonal or environmental effects, or a combination of these factors. To address the role of gonadal hormones on axon myelination, functional axon conduction and immunohistochemistry analysis of the CC in intact, gonadectomized and hormone-replaced gonadectomized animals were used. These groups were subjected to cuprizone diet-induced demyelination followed by remyelination. The myelinated component of callosal compound action potential was significantly decreased in ovariectomized and castrated animals under normal myelinating condition. Compared to gonadally intact cohorts, both gonadectomized groups displayed more severe demyelination and inhibited remyelination. Castration in males was more deleterious than ovariectomy in females. Callosal conduction in estradiol-supplemented ovariectomized females was significantly increased during normal myelination, less attenuated during demyelination, and increased beyond placebo-treated ovariectomized or intact female levels during remyelination. In castrated males, the non-aromatizing steroid dihydrotestosterone was less efficient than testosterone and estradiol in restoring normal myelination/axon conduction and remyelination to levels of intact males. Furthermore, in both sexes, estradiol supplementation in gonadectomized groups increased the number of oligodendrocytes. These studies suggest an essential role of estradiol to promote efficient CC myelination and axon conduction in both sexes.

Dynamic development of glucocorticoid resistance during autoimmune neuroinflammation.

CONTEXT: Glucocorticoids (GC) are powerful endogenous and therapeutic modulators of inflammation and play a critical role for controlling autoimmunity. GC resistance can be seen in patients with cell-mediated autoimmune disorders, but it is unknown whether this represents a stable trait or a state. OBJECTIVE: The objective of the study was to determine whether GC resistance of T cell responses is dynamically regulated in experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS). DESIGN: This was a translational observational study. PATIENTS AND ANIMALS: EAE was induced in C57BL/6 mice. A cross-sectional sample of 25 patients with relapsing-remitting MS was included as well as four MS patients during pregnancy and postpartum. MAIN OUTCOME MEASURES: Outcome measures included GC sensitivity of T cell proliferation and GC-mediated apoptosis. RESULTS: GC resistance was seen in both autoantigen-specific and nonspecific responses of T cells obtained from mice with EAE. GC resistance preceded clinical symptoms and central nervous system infiltration of immune cells. T cells obtained during EAE were resistant to GC-induced apoptosis, and this was linked to down-regulation of GC receptor-α expression. GC resistance in T cells was also seen in MS patients with radiological evidence for ongoing inflammation. GC resistance was absent in the MS patients during pregnancy, when relapse risk is decreased, but recurred postpartum, a time of increased relapse risk. CONCLUSIONS: These data demonstrate that GC resistance during autoimmune neuroinflammation is dynamically regulated. This has implications for the timing of steroid treatments and provides a putative pathway to explain the observed association between psychological stress and exacerbation of autoimmune diseases.

Predictors of outcome after radiofrequency catheter ablation of the atrioventricular node for atrial fibrillation and congestive heart failure.

BACKGROUND: Although radiofrequency catheter ablation of the atrioventricular (AV) node is an established treatment for atrial fibrillation (AF) with uncontrolled ventricular response, factors that predict clinical outcome in patients with associated congestive heart failure (CHF) are unknown. METHODS AND RESULTS: AV node ablation and permanent pacemaker implantation was performed in 44 consecutive patients (mean age 71+/-10 years) with CHF and AF associated with uncontrolled ventricular response. Immediately before ablation, mean left ventricular ejection fraction (EF) measured by 2-dimensional echocardiogram was 34.6%+/-9.8%, mean exercise tolerance time was 2.6+/-1.8 minutes, and mean quality of life score was 62.3+/-19.7. Complete AV block was achieved in all 44 patients but was complicated by death in 1 patient from cardiogenic shock soon after ablation. By 1 month after ablation, EF increased to 43.8%+/-13.7% (P < .01), exercise tolerance time was 4.0+/-2.5 minutes (P < .01), and mean quality of life score decreased to 35.6+/-18.1 (P < .01). Improved cardiac performance (increase in EF > or = 9% over baseline EF) was detected in 20 (45%) of the patients. During a mean follow-up of 17+/-9 months, 5 patients died suddenly of presumed ventricular tachyarrhythmia and 4 others died of progressive CHF. Multivariate Cox survival analysis identified baseline EF < or = 30%, presence of significant mitral regurgitation (>2+) before ablation, and failure to exhibit improved cardiac performance by 1 month after ablation as the only independent predictors of death. CONCLUSIONS: Baseline variables and failure of EF to improve soon after AV node ablation identifies patients with CHF and AF who have a high mortality rate. Adjunctive therapy to reduce sudden death and progressive heart failure should be evaluated in this subgroup.

The high cost of syncope: cost implications of a new insertable loop recorder in the investigation of recurrent syncope.

BACKGROUND: Patients with recurrent syncope frequently undergo extensive investigations that consume significant health care resources. Recent advances in long-term monitoring techniques have enhanced diagnostic yield in patients with infrequent symptoms. There is little information on the relative cost-effective profile of the investigative tools used in patients with syncope. METHODS: Two methods to determine health care costs in patients with syncope were used. In the first, health care resource utilization was determined in 24 patients with recurrent unexplained syncope and negative investigations who underwent insertion of the implantable loop recorder (ILR) during a pilot study of the feasibility of the device. The costs of investigations before, during, and after ILR implantation in each patient were calculated on the basis of median charges for an index investigation and a regression analysis of 1018 US Medicare hospital claims for syncope from 1993. Charges were converted to costs using a cost-to-charge ratio of 0.64. The second method was based on estimated costs per diagnosis and published diagnostic yields of 6 commonly applied tests in patients with syncope. A cohort simulation using theoretic models of 100 patients undergoing investigation for syncope was created to compare the diagnostic yield and cost per diagnosis of various diagnostic cascades. RESULTS: In the pilot study, the cost of investigation of syncope in the 2 years before ILR insertion was $7584 per patient. After the ILR was inserted, a diagnosis was obtained in 21 of 24 patients (diagnostic yield 88%). The cost of therapy was $2452, followed by a reduction in cost of care to $596 over 30 +/- 10 months of follow-up. In the second method, the diagnostic yield of individual tests ranged from 3% for echocardiography to 88% for the ILR. The cost per diagnosis obtained ranged from $529 for the external loop recorder to $73,260 for electrophysiologic testing in patients without structural heart disease. An approach to syncope similar to that of the ILR pilot study resulted in a cost per diagnosis of $3193 and a diagnostic yield of 98%. Performance of echocardiography in half of the patients and electrophysiologic testing only in the presence of structural heart disease reduced the cost to $2494 and retained a diagnostic yield of 98%. CONCLUSIONS: The cost of investigation of syncope is high. The ILR may reduce health care resource utilization by providing a diagnosis permitting definitive therapy. The cost per diagnosis profile of current diagnostic tests commonly used in patients with syncope is highly variable. A cost-effective approach to diagnosing this disorder can retain a high diagnostic yield with a reduction in resource utilization compared with a conventional approach.

The costs of recurrent syncope of unknown origin in elderly patients.

Although syncope has been shown to reduce quality-of-life, its impact on resource costs has not been documented. The objective of this study was to quantify the annual medical costs of caring for elderly patients with syncope, especially recurrent syncope of unknown origin. Administrative data from the Health Care Financing Administration were obtained on 7,959 Medicare patients who had at least one inpatient admission with a diagnosis of syncope in 1993. The costs of any inpatient admissions, outpatient procedures, or physician visits with an ICD-CM-9 diagnosis for syncope were summed for a 365-day period from the date of the initial hospitalization for syncope. Patients who had at least two hospitalizations with admission and discharge diagnosis of syncope were deemed to have recurrent syncope of uncertain origin. To better estimate syncope costs for those whose syncope costs could have been attributed to other diagnoses, a regression analysis was performed including variables representing the most frequent secondary diagnoses. The average annual costs of those who were admitted with syncope but who were discharged with another diagnosis was $4,942 in 1993. The average annual cost of patients with recurrent syncope deemed to be of unknown origin was $5,165. For those patients with secondary diagnoses of atherosclerosis, urinary tract infections, or hypokalemia, the annual costs of syncope averaged $6,820, $7,013, or $7,949, respectively.

Mitral regurgitation after atrioventricular node catheter ablation for atrial fibrillation and heart failure: acute hemodynamic features.

BACKGROUND: Radiofrequency catheter ablation of the atrioventricular node and pacemaker insertion have been associated with occasional development of mitral regurgitation (MR). Ventricular pacing might result in MR if (1) left ventricular (LV) compliance is decreased and/or (2) mitral valve leaflet apposition is disturbed. We studied acute hemodynamic changes resulting from initiation of ventricular pacing in patients undergoing ablation. METHODS AND RESULTS: Thirteen patients (10 men and 3 women) with a mean age of 73.4 +/- 8. 6 years, with chronic atrial fibrillation and congestive heart failure, had permanent ventricular pacemaker insertion with lead placement at the right ventricular (RV) apex. The following hemodynamic recordings were obtained before ablation (during atrial fibrillation) and then immediately after ablation (during RV pacing): heart rate, mean arterial pressure, LV end-diastolic pressure (LVEDP), mean pulmonary capillary wedge pressure, V-wave amplitude, and cardiac index. Presence of MR was assessed by V-wave amplitude and the results of LV angiography. In patients who had MR, recordings were also obtained during temporary ventricular pacing from the RV outflow tract (RVOT). As a group there were no significant changes in any hemodynamic measurement. Before ablation, mild MR by LV angiogram was present in 5 patients, but none had large V-wave amplitude. After ablation, mild MR was present by LV angiogram in 6 patients, and in 3 of these patients large V-wave amplitude developed (mean amplitude 42.7 +/- 2.2 mm Hg; assigned to group 1). This was associated with a rise in LVEDP in 1 patient (consistent with reduced LV compliance), but LVEDP was unchanged in the other 2 patients (suggesting abnormal mitral valve leaflet apposition). All patients in group 1 exhibited a fall in V-wave amplitude when the pacing site was moved to the RVOT. CONCLUSIONS: Both reduced LV compliance and disturbed mitral valve leaflet apposition contribute to MR after ablation. MR is reduced by pacing from the RVOT.

Characteristics of contraceptive acceptors in Lusaka, Zambia.

This paper reports on a study conducted in Lusaka, Zambia in which 2,912 client records were examined in 22 randomly selected clinics throughout Lusaka Province. The purpose of the study was to assist the government and the local family planning association in targeting future efforts to extend services to underserved populations. Among newly enrolled acceptors in 1984, the study revealed a surprisingly low median age of 24 and a median parity of 3. The majority were married, had some secondary education, were unemployed housewives, and were breastfeeding at the time of the first visit. Nearly half had used contraceptives before. Over three-fourths of the clients received contraceptive pills when they enrolled. They returned to the clinic an average of 2.4 times during the first year, but only 24 percent were still active after 12 months. The availability of recently released census data allowed a comparison of contraceptive acceptors with women in the general Lusaka population. Data from urban clinics and smaller clinics in rural parts of the province revealed few significant rural-urban differences. Finally, the study examined trends in age, parity, and education of contraceptive users over a ten-year period.

PIP: This paper reports on a study conducted in Lusaka, Zambia in which 2912 client records were examined in 22 randomly selected clinics throughout Lusaka Province. The purpose of the study was to assist the government and the local family planning association in targeting future efforts to extend services to underserved populations. Among newly enrolled acceptors in 1984, the study revealed a surprisingly low median age of 24 and a median parity of 3. The majority were married, had some 2ndary education, were unemployed housewives, and were breastfeeding at the time of the 1st visit. Nearly 1/2 had used contracepties before. Over 3/4 of the clients received contraceptive pills when they enrolled. They returned to the clinic an average of 2.4 times during the 1st year, but only s4% were still active after 12 months. The availbility of recently released census data allowed a comparison of contraceptive acceptors with women in the general Lusaka population. Data from urban clinics and smaller clinics in rural parts of the province revealed few significant rural-urban differences. Finally, the study examined trends in age, parity, and education of contraceptive users over a 10 year period.