Real-Time Precision Needle Tracking for Gynecological Interstitial Brachytherapy: A Phantom Feasibility Study

PURPOSE/OBJECTIVE(S)

To determine if an advanced needle navigation and real-time precision tracking system developed for prostate biopsies can be used for the purpose of real-time guidance of interstitial needles in modern image-guided gynecologic brachytherapy.

MATERIALS/METHODS

An agarose gel pelvic phantom was previously designed using 3D Slicer and Autodesk Fusion360 to model an average uterus from a 50-patient dataset, a vaginal canal from KleenSpec (TM, Welch Allyn) speculum dimensions, and a rectum to accommodate a BK 8848 endocavity biplane ultrasound [US] probe. After manufacturing the phantom with a 7.2cm x 3.7cm x 4.4cm (LxWxH) uterus and an attached 2.7cm x 1.4cmx 1.7cm (LxWxH) focal HR-CTV target, the model was imaged using MRI. The uterus and HR-CTV were contoured on MRI to aid in registration with US and provide a target for needle placement. The tracking system with endorectal probe was then used to image the phantom. Ultrasound images from a 180-degree sweep were acquired and a 3D Ultrasound-based volume was generated. Using the commercially available system, the MRI was imported and an MRI-Ultrasound fusion performed based on the uterus contours and then refined using contour-based deformable registration. Three desired locations for needle placement were defined to test the ability of the system to guide needles at these locations: one in the most lateral aspect of the HRCTV, one at the HRCTV-uterus interface, and one inside the uterus. The needle tracking sleeve that was indexed to the probe was used in conjunction with the software interface to guide the 17-gauge titanium needle placement in real time. The distance between actual needle and the intended needle location was measured for each successful needle placement. When possible, needles were removed and reinserted at the same desired location to test the reproducibility of insertion under US guidance.

RESULTS

Two of the three intended needles were successfully placed using real-time US guidance. The most lateral needle in the HRCTV was not inserted due to limitations of the phantom design, specifically inaccessibility to the agarose phantom through the phantom wall supports. The inserted needles were visible and tracked to the desired location within 0.6 mm (needle located at HRCTV-uterus interface), and 2.2 mm (needles inserted centrally in the uterus). For the target within the uterus, needles were reinserted at the same target of interest with a ∆ 0.15mm in greatest range between attempts.

CONCLUSION

We have demonstrated a proof of concept in which existing technology for prostate biopsies can be utilized for the application of interstitial gynecologic brachytherapy with a high degree of fidelity. Ongoing modifications to our validation phantom and the tracking system are needed to allow for variations in uterine anatomy, more rigorous evaluation of reproducibility, and multi-catheter placement.

Effect of Bacillus coagulans Unique IS2 with Lactulose on Functional Constipation in Adults: a Double-Blind Placebo Controlled Study

In the present double-blind randomised study, the efficacy of combination of Bacillus coagulans Unique IS2 and lactulose was evaluated in the treatment of functional constipation in adults. One-fifty participants diagnosed with functional constipation (Rome III criteria) were randomised (1:1:1) and supplemented daily with 15 mL suspension of probiotic (B. coagulans Unique IS2, 2 × 10⁹ spores) with lactulose (10 g) (group 1) or lactulose (10 g) (group 2) or placebo (water) (group 3) for 4 weeks. The primary (stool frequency) and secondary outome measures (stool consistency, sensation of incomplete evacuation, defecation- and abdominal-pain) were recorded weekly for up to 4 weeks. Bacillus coagulans Unique IS2 with lactulose showed significant changes in stool frequency as compared to lactulose treatment; however, at the end of the trial, it was found insignificant due to the gradual increase of stool frequency score of lactulose treatment. The changes observed in stool consistency were early (2nd week) and remained consistent up to end of the trial. The significant reduction of sensation of incomplete evacuation, defecation-, and abdominal-pain correlated with the strains ability to produce short-chain fatty acids. No adverse events were observed in any of the groups, and all the vital parameters were normal during the course of the study. Overall, results indicated that B. coagulans Unique IS2 addition to lactulose reduced time required to relieve constipation as compared to lactulose alone. In conclusion, B. coagulans Unique IS2 with lactulose is more effective than lactulose alone to relieve symptoms of constipation in a shorter period. Trial registration: CTRI/2018/11/016399, dated 22/11/2018.

The Purkinje-myocardial junction is the anatomic origin of ventricular arrhythmia in CPVT

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmia syndrome caused by gene mutations that render RYR2 Ca release channels hyperactive, provoking spontaneous Ca release and delayed afterdepolarizations (DADs). What remains unknown is the cellular source of ventricular arrhythmia triggered by DADs: Purkinje cells in the conduction system or ventricular cardiomyocytes in the working myocardium. To answer this question, we used a genetic approach in mice to knock out cardiac calsequestrin either in Purkinje cells or in ventricular cardiomyocytes. Total loss of calsequestrin in the heart causes a severe CPVT phenotype in mice and humans. We found that loss of calsequestrin only in ventricular myocytes produced a full-blown CPVT phenotype, whereas mice with loss of calsequestrin only in Purkinje cells were comparable to WT mice. Subendocardial chemical ablation or restoration of calsequestrin expression in subendocardial cardiomyocytes neighboring Purkinje cells was sufficient to protect against catecholamine-induced arrhythmias. In silico modeling demonstrated that DADs in ventricular myocardium can trigger full action potentials in the Purkinje fiber, but not vice versa. Hence, ectopic beats in CPVT are likely generated at the Purkinje-myocardial junction via a heretofore unrecognized tissue mechanism, whereby DADs in the ventricular myocardium trigger full action potentials in adjacent Purkinje cells.

Comparison of geographic workflow preferences with real-time dynamic regional mapping data during catheter ablation

Funding Acknowledgements

Type of funding sources: None.

Introduction

The clinical benefit of multielectrode high-density (HD) mapping during catheter ablation has been an area of active research. One advantage of HD mapping is improved sensitivity which can lead to better visualization and substrate delineation during the procedure. In addition to the advantages offered by the multielectrode grid mapping catheter (HD Grid), a novel software enable the display of beat-to-beat, dynamic regional mapping data from the current location of HD Grid in real-time (LiveView). The optimal settings and workflows to incorporate the dynamic data into routine ablation procedures have not been explored.

Purpose

To examine the common settings and workflow patterns among operators from different geographies when using dynamic mapping.

Methods

Observational procedural data including procedure time, total RF time, workflow preference, and fluoroscopy time, were prospectively collected from operators across Europe, the U.S., and Asia Pacific countries from May to September 2020. Cases from both catheter ablation of atrial and ventricular arrhythmias were included in the analysis.

Results

A total of 754 cases were collected (428, 133, and 193 cases from Europe, the U.S., and the Asia Pacific region, respectively). The most commonly reported indication across all three geographies was de novo paroxysmal atrial fibrillation (223/754, 30.0%). A steerable sheath was more frequently used with the mapping catheter in Europe and U.S. compared to Asia Pacific countries. Contrary to cases from the U.S. and Asia Pacific countries where the double transseptal approach was the preferred technique for left atrial procedures (78.8% and 55.3%, respectively), the single transseptal approach was more commonly observed in European cases (233/428, 54.4%). Visualization of real-time mapping data after creation of traditional full-chamber maps were commonly observed in all three geographies. Regardless of geography, the CS catheter was commonly used a reference electrode; and the most common map appearance settings for interior projection, exterior projection, and interpolation was 7, 7, and 7 respectively. Voltage cutoff of 0.1 mV, range from 0.01 to 1.5 mV, was most frequently observed for delineating scar in atrial arrhythmia cases analyzed in this dataset.

Conclusions

While there is a geographical difference in ablation workflow, common settings and patterns can be observed in all three regions. This data suggests that minimal workflow changes are required to incorporate the use of dynamic data into routine procedures. Adaptation of LiveView can help improve procedure efficiency and efficacy by reducing the need for full chamber maps, identifying areas that were under ablated, and confirming ablation endpoints. Further control study examining procedure efficiency and efficacy associated with dynamic mapping may be warranted.

Noncovalent interactions from electron density topology and solvent effects on spectral properties of Schiff bases

Two Schiff bases were prepared by the condensation of o-allyl substituted 2,4-dihydroxy acetophenone with 1,2-diaminopropane (L1) and ethanediamine (L2) and characterized by elemental analysis, and ESI-MS, IR, UV-Vis, ¹H and ¹³C NMR spectral techniques. The effect of solvents with respect to different polarities on UV-Vis and emission spectra of L1 and L2 was investigated at room temperature show that the compounds exist in keto and enol forms in solution and may be attributed to the intramolecular proton transfer in the ground state. The solute-solvent interactions, change in dipole moment and solvatochromic properties of the compounds were studied based on the solvent polarity parameters. For L1 and L2, the ground and excited state electronic structure calculations were carried out by DFT and TD-DFT at B3LYP/6-311G (d,p) level, respectively. The IR, NMR and electronic absorption spectra computed were compared with the experimental observations. The intramolecular charge transfer within the molecule is evidenced from the HOMO and LUMO energy levels and surface analysis. The noncovalent interactions like hydrogen bonding and van der Waals interactions were identified from the molecular geometry and electron localization function. These interactions in molecules have been studied by using reduced density gradient and graphed by Multiwfn.

Clinical utility of urine neutrophil gelatinase-associated lipocalin measured at admission to predict outcomes in heterogeneous population of critically ill patients

Urine neutrophil gelatinase-associated lipocalin (uNGAL) is a reliable early biomarker of acute kidney injury (AKI) in a homogeneous patient population. However, its utility in a heterogeneous population of critically ill, in whom the time of onset of renal insult is often unclear, is not clearly established. We evaluated the ability of a single measurement of uNGAL in a heterogeneous adult population, on admission to intensive care unit (ICU), to predict the occurrence of AKI and hospital mortality. One hundred and two consecutive adult patients had uNGAL measured within 8 h of admission to ICU. The demographic and laboratory data were collected at admission. The diagnosis of AKI was based on AKI Network (AKIN) criteria. The primary outcome was the development of AKI, and the secondary outcome was hospital mortality. The mean age was 54 ± 16.4 years and 65% were males. Urine NGAL (ng/ml) was 69 ± 42 in patients with AKI (n = 42) and 30.4 ± 41.7 in those without AKI (P < 0.001). The area under the receiver operating characteristic (ROC) curve for prediction of AKI was 0.79 and for serum creatinine (SCr) was 0.88. The sensitivity and specificity for a cut-off value of uNGAL of 75 ng/ml to predict AKI were 0.5 and 0.85 respectively. uNGAL > 75 ng/ml was a strong (odd ratio = 5.17, 95% confidence interval: 1.39–19.3) and independent predictor of hospital mortality. A single measurement of uNGAL at admission to ICU exhibited good predictive ability for AKI though the sensitivity was low. The predictive ability of uNGAL was inferior to simultaneously measured SCr at admission, hence limited its clinical utility to predict AKI. However, admission uNGAL was a strong, independent predictor of hospital mortality.

Suppression of spontaneous ca elevations prevents atrial fibrillation in calsequestrin 2-null hearts

BACKGROUND

Atrial fibrillation (AF) risk has been associated with leaky ryanodine receptor 2 (RyR2) Ca release channels. Patients with mutations in RyR2 or in the sarcoplasmic reticulum Ca-binding protein calsequestrin 2 (Casq2) display an increased risk for AF. Here, we examine the underlying mechanisms of AF associated with loss of Casq2 and test mechanism-based drug therapy.

METHODS AND RESULTS

Compared with wild-type Casq2+/+ mice, atrial burst pacing consistently induced atrial flutter or AF in Casq2-/- mice and in isolated Casq2-/- hearts. Atrial optical voltage maps obtained from isolated hearts revealed multiple independent activation sites arising predominantly from the pulmonary vein region. Ca and voltage mapping demonstrated diastolic subthreshold spontaneous Ca elevations (SCaEs) and delayed afterdepolarizations whenever the pacing train failed to induce AF. The dual RyR2 and Na channel inhibitor R-propafenone (3 μmol/L) significantly reduced frequency and amplitude of SCaEs and delayed afterdepolarizations in atrial myocytes and intact atria and prevented induction of AF. In contrast, the S-enantiomer of propafenone, an equipotent Na channel blocker but much weaker RyR2 inhibitor, did not reduce SCaEs and delayed afterdepolarizations and failed to prevent AF.

CONCLUSIONS

Loss of Casq2 increases risk of AF by promoting regional SCaEs and delayed afterdepolarizations in atrial tissue, which can be prevented by RyR2 inhibition with R-propafenone. Targeting AF caused by leaky RyR2 Ca channels with R-propafenone may be a more mechanism-based approach to treating this common arrhythmia.

Self-perceived health-related quality of life of Indian children with specific learning disability

BACKGROUND

Specific learning disability (SpLD) often remains undetected, resulting in the afflicted child experiencing chronic poor school performance.

AIMS

To measure and analyze the self-perceived health-related quality of life (HRQoL) of children with newly-diagnosed SpLD.

SETTINGS AND DESIGN

Cross-sectional questionnaire-based study in our clinic.

MATERIALS AND METHODS

From February to December 2008, 150 children consecutively diagnosed as having SpLD were enrolled and their HRQoL documented using the DISABKIDS chronic generic module self-report version instrument.

STATISTICAL ANALYSIS

Multiple regression analysis was carried out for determining the 'independent' impact that each of the clinical and socio-demographic variables had on a poor facet score outcome and on a poor total score outcome.

RESULTS

Clinically significant deficits were detected in all 6 facets, namely: 'large deficits (effect size ≥-0.8)' in "social exclusion", "emotion", "limitation", "treatment", and "independence"; and 'medium deficit (effect size -0.5 to <-0.8)' in "social inclusion"; and 'large deficit' in "total score". Multivariate analysis revealed that: (i) not belonging to the upper socio-economic strata of society was an independent predictor of a poor "independence" facet outcome (P=0.010, OR=1.99, 95% CI: 1.18 to 3.37); (ii) not having experienced class detainment was an independent predictor of a poor "emotion" facet outcome (P=0.008, OR=3.04, 95% CI: 1.34 to 6.85); (iii) first-born status was an independent predictor of a poor "limitation" facet outcome (P=0.022, OR=2.60, 95% CI: 1.15 to 5.90); and (iv) female gender was an independent predictor of a poor "social exclusion" facet outcome (P=0.024, OR=0.28, 95% CI: 0.09 to 0.85) and a poor "overall health" outcome (P=0.025, OR=0.32, 95% CI: 0.12 to 0.87).

CONCLUSIONS

Children with newly-diagnosed SpLD perceive their psychosocial, physical, and overall HRQoL to be significantly compromised.

Myofilament calcium de-sensitization and contractile uncoupling prevent pause-triggered ventricular tachycardia in mouse hearts with chronic myocardial infarction

Myocardial infarction (MI) is a major risk for ventricular arrhythmia. Pause-triggered ventricular arrhythmia can be caused by increased myofilament Ca binding due to sarcomeric mutations or Ca-sensitizing compounds. Myofilament Ca sensitivity is also increased after MI. Here we hypothesize that MI increases risk for pause-triggered ventricular arrhythmias, which can be prevented by myofilament Ca-desensitization and contractile uncoupling. To test this hypothesis, we generated a murine chronic MI model using male B6SJLF1/J mice (n=40) that underwent permanent ligation of the left anterior descending coronary artery. 4 weeks post MI, cardiac structure, function and myofilament Ca sensitivity were evaluated. Pause-dependent arrhythmia susceptibility was quantified in isolated hearts with pacing trains of increasing frequency, followed by a pause and an extra stimulus. Coronary ligation resulted in a mean infarct size of 39.6±5.7% LV and fractional shortening on echocardiography was reduced by 40% compared to non-infarcted controls. Myofilament Ca sensitivity was significantly increased in post MI hearts (pCa50: Control=5.66±0.03; MI=5.84±0.05; P<0.01). Exposure to the Ca desensitizer/contractile uncoupler blebbistatin (BLEB, 3 μM) reduced myofilament Ca sensitivity of MI hearts to that of control hearts and selectively reduced the frequency of post-pause ectopic beats (MI 0.12±0.04 vs MI+BLEB 0.01±0.005 PVC/pause; P=0.02). BLEB also reduced the incidence of ventricular tachycardia in chronic MI hearts from 59% to 10% (P<0.05). We conclude that chronic MI hearts exhibit increased myofilament Ca sensitivity and pause-triggered ventricular arrhythmias, which can be prevented by blebbistatin. Decreasing myofilament Ca sensitivity may be a strategy to reduce arrhythmia burden after MI.

Focal energy deprivation underlies arrhythmia susceptibility in mice with calcium-sensitized myofilaments

RATIONALE

The Ca(2+) sensitivity of the myofilaments is increased in hypertrophic cardiomyopathy and other heart diseases and may contribute to a higher risk for sudden cardiac death. Ca(2+) sensitization increases susceptibility to reentrant ventricular tachycardia in animal models, but the underlying mechanism is unknown.

OBJECTIVE

To investigate how myofilament Ca(2+) sensitization creates reentrant arrhythmia susceptibility.

METHODS AND RESULTS

Using hypertrophic cardiomyopathy mouse models (troponinT-I79N) and a Ca(2+) sensitizing drug (EMD57033), here we identify focal energy deprivation as a direct consequence of myofilament Ca(2+) sensitization. To detect ATP depletion and thus energy deprivation, we measured accumulation of dephosphorylated Connexin 43 (Cx43) isoform P0 and AMP kinase activation by Western blotting and immunostaining. No differences were detected between groups at baseline, but regional accumulation of Connexin 43 isoform P0 occurred within minutes in all Ca(2+)-sensitized hearts, in vivo after isoproterenol challenge and in isolated hearts after rapid pacing. Lucifer yellow dye spread demonstrated reduced gap junctional coupling in areas with Connexin 43 isoform P0 accumulation. Optical mapping revealed that selectively the transverse conduction velocity was slowed and anisotropy increased. Myofilament Ca(2+) desensitization with blebbistatin prevented focal energy deprivation, transverse conduction velocity slowing, and the reentrant ventricular arrhythmias.

CONCLUSIONS

Myofilament Ca(2+) sensitization rapidly leads to focal energy deprivation and reduced intercellular coupling during conditions that raise arrhythmia susceptibility. This is a novel proarrhythmic mechanism that can increase arrhythmia susceptibility in structurally normal hearts within minutes and may, therefore, contribute to sudden cardiac death in diseases with increased myofilament Ca(2+) sensitivity.

Identification and characterization of a compound that protects cardiac tissue from human Ether-à-go-go-related gene (hERG)-related drug-induced arrhythmias

The human Ether-à-go-go-related gene (hERG)-encoded K(+) current, I(Kr) is essential for cardiac repolarization but is also a source of cardiotoxicity because unintended hERG inhibition by diverse pharmaceuticals can cause arrhythmias and sudden cardiac death. We hypothesized that a small molecule that diminishes I(Kr) block by a known hERG antagonist would constitute a first step toward preventing hERG-related arrhythmias and facilitating drug discovery. Using a high-throughput assay, we screened a library of compounds for agents that increase the IC(70) of dofetilide, a well characterized hERG blocker. One compound, VU0405601, with the desired activity was further characterized. In isolated, Langendorff-perfused rabbit hearts, optical mapping revealed that dofetilide-induced arrhythmias were reduced after pretreatment with VU0405601. Patch clamp analysis in stable hERG-HEK cells showed effects on current amplitude, inactivation, and deactivation. VU0405601 increased the IC(50) of dofetilide from 38.7 to 76.3 nM. VU0405601 mitigates the effects of hERG blockers from the extracellular aspect primarily by reducing inactivation, whereas most clinically relevant hERG inhibitors act at an inner pore site. Structure-activity relationships surrounding VU0405601 identified a 3-pyridiyl and a naphthyridine ring system as key structural components important for preventing hERG inhibition by multiple inhibitors. These findings indicate that small molecules can be designed to reduce the sensitivity of hERG to inhibitors.

Myofilament Ca sensitization increases cytosolic Ca binding affinity, alters intracellular Ca homeostasis, and causes pause-dependent Ca-triggered arrhythmia

RATIONALE

Ca binding to the troponin complex represents a major portion of cytosolic Ca buffering. Troponin mutations that increase myofilament Ca sensitivity are associated with familial hypertrophic cardiomyopathy and confer a high risk for sudden death. In mice, Ca sensitization causes ventricular arrhythmias, but the underlying mechanisms remain unclear.

OBJECTIVE

To test the hypothesis that myofilament Ca sensitization increases cytosolic Ca buffering and to determine the resulting arrhythmogenic changes in Ca homeostasis in the intact mouse heart.

METHODS AND RESULTS

Using cardiomyocytes isolated from mice expressing troponin T (TnT) mutants (TnT-I79N, TnT-F110I, TnT-R278C), we found that increasing myofilament Ca sensitivity produced a proportional increase in cytosolic Ca binding. The underlying cause was an increase in the cytosolic Ca binding affinity, whereas maximal Ca binding capacity was unchanged. The effect was sufficiently large to alter Ca handling in intact mouse hearts at physiological heart rates, resulting in increased end-diastolic [Ca] at fast pacing rates, and enhanced sarcoplasmic reticulum Ca content and release after pauses. Accordingly, action potential (AP) regulation was altered, with postpause action potential prolongation, afterdepolarizations, and triggered activity. Acute Ca sensitization with EMD 57033 mimicked the effects of Ca-sensitizing TnT mutants and produced pause-dependent ventricular ectopy and sustained ventricular tachycardia after acute myocardial infarction.

CONCLUSIONS

Myofilament Ca sensitization increases cytosolic Ca binding affinity. A major proarrhythmic consequence is a pause-dependent potentiation of Ca release, action potential prolongation, and triggered activity. Increased cytosolic Ca binding represents a novel mechanism of pause-dependent arrhythmia that may be relevant for inherited and acquired cardiomyopathies.

Intracellular Ca(2+) accumulation is strain-dependent and correlates with apoptosis in aortic valve fibroblasts

Aortic valve (AV) disease is often characterized by the formation of calcific nodules within AV leaflets that alter functional biomechanics. In vitro, formation of these nodules is associated with osteogenic differentiation and/or increased contraction and apoptosis of AV interstitial cells (AVICs), leading to growth of calcium phosphate crystal structures. In several other cell types, increased intracellular Ca(2+) has been shown to be an important part in activation of osteogenic differentiability. However, elevated intracellular Ca(2+) is known to mediate cell contraction, and has also been shown to lead to apoptosis in many cell types. Therefore, a rise in intracellular Ca(2+) may precede cellular changes that lead to calcification, and fibroblasts similar to AVICs have been shown to exhibit increases in intracellular Ca(2+) in response to mechanical strain. In this study, we hypothesized that strain induces intracellular Ca(2+) accumulation through stretch-activated calcium channels. We were also interested in assessing possible correlations between intracellular Ca(2+) increases and apoptosis in AVICs. To test our hypothesis, cultured porcine AVICs were used to assess correlates between strain, intracellular Ca(2+), and apoptosis. Ca(2+) sensitive fluorescent dyes were utilized to measure real-time intracellular Ca(2+) changes in strained AVICs. Ca(2+) changes were then correlated with AVIC apoptosis using flow cytometric Annexin V apoptosis assays. These data indicate that strain-dependent accumulation of intracellular Ca(2+) is correlated with apoptosis in AVICs. We believe that these findings indicate early mechanotransductive events that may initiate AV calcification pathways.

On-pump vs. off-pump coronary artery bypass surgery at a non-academic community hospital: have biocompatibility improvements eliminated the superiority of off-pump surgery?

OBJECTIVES

Standard coronary artery bypass grafting (CABG) surgery involves cardiopulmonary bypass (CPB) but given concerns over neurological and inflammatory complications related to CPB, many patients receive so-called off-pump procedures (OPCABG). Our objective is to determine if the recent improvements in the biocompatibility of CPB circuitry have improved post-operative outcomes at the community hospital level, particularly in terms of hospital length of stay (LOS), stroke and post-operative infection.

METHODS

We analyzed hospital LOS, incidence of stroke, infection, and mortality along with several clinical variables in 209 patients (38% underwent OPCABG) at a single, non academic community hospital. We constructed a series of forward, stepwise, multiple-variable regression models using mediastinal infection, hospital LOS, and stroke as dependant variables.

RESULTS

OPCABG was associated with a shorter median hospital LOS (3 days vs. 4 days; p=0.0001) and a reduced occurrence of stroke (0% vs. 7.6%; p=0.03). However, mediastinal infections occurred more commonly in OPCABG cases (10% vs. 2.2%; p=0.02). CABG and pre-existing renal disease were predictors of increased hospital LOS (p< 0.0001) whereas CABG was the only factor associated with decreased risk of mediastinal infection (OR=0.21 (0.05-0.80); p=0.02).

CONCLUSIONS

At the community level, OPCABG appears to be superior in terms of LOS and incidence of stroke. Paradoxically, CABG surgery demonstrates a reduced rate of mediastinal infection.

Uncertainty in rate loss corrections based on counting a periodic pulser

Tomographic gamma scanning of waste produces three-dimensional transmission and emission images. These are used to derive item-specific attenuation correction factors that improve the accuracy of non-destructive waste assay. For each vertical layer, data grabs of short duration are acquired as the waste item is rotated and translated. The image reconstruction demands accurate rate loss corrections to minimize assay bias. For this application a pulser was used to perform the necessary rate loss corrections. In this work, we summarize the benefits of the pulser approach and review the basic principles on which the method is based. We extend the treatment to include a derivation of the expression for the uncertainty in the net pulser peak area in the presence of an underlying continuum. We report experimental results, taken using a Canberra model WM2900 Tomographic Gamma Scanner, over a broad range of count-rates and peak-to-continuum ratios. Repeat counts under controlled conditions allowed the correction factor and its variance to be determined and compared against expectations. These results confirm the validity of the correction factor formula and the corresponding expression for its uncertainty. The rate loss analysis has been built into a Monte Carlo Replicate engine to allow the uncertainty to be propagated into the total measurement uncertainty of the final assay.

Application of blood purification to non-renal organ failure

The application of artificial organs to the task of blood purification in the setting of non-renal organ failure simultaneously presents important challenges and opportunities. Failures of cardiovascular, hepatic, coagulation and immune systems are all characterized by dysregulation leading to multi-organ failure. When sustained, these conditions result in multiple organ system dysfunction and death and are far too common in modern intensive care units (ICUs). While the pathogenesis of each of these organ failures is complex and variable, brought about by a variety of underlying conditions, the potential to improve patient outcomes by simultaneously targeting multiple pathways can perhaps best be realized by blood purification. Unlike drug strategies, which are usually limited to one component of these complex networks, blood purification is, by its very nature, broad spectrum and self regulating. For example, as the concentration of mediators or toxins increases, so does removal. Furthermore, given the many failed trials of specific therapy, the recent focus of immunomodulatory therapy in sepsis has shifted to non-specific methods of influencing the entire inflammatory response without suppressing it. In this issue of the journal, members of the Acute Dialysis Quality Initiative (ADQI) present systematic reviews on the application of hemofiltration, ultrafiltration, plasma therapies and liver-assist therapy for the treatment of non-renal organ failure. The focus of these reviews is on clinical evidence as well as recommendations for future research.

A lignan from the root of Ecbolium linneanum Kurz

From the chloroform extract of the root of Ecbolium linneanum Kurz., a furofuran type of unsymmetrical lignan named as Ecbolin A was isolated. The structure was established by spectroscopic methods and confirmed by single crystal X-ray diffraction studies.

Mechanism of action of Escherichia coli formamidopyrimidine N-glycosylase: role of K155 in substrate binding and product release

Escherichia coli formamidopyrimidine N-glycosylase (fpg) is a DNA glycosylase with an associated beta,delta-lyase activity. We have recently shown that the highly conserved lysine residue K155 is important for base recognition. Incubation of a double-stranded DNA containing an abasic site with the wild-type fpg protein generated only beta,delta-product. However, incubation of a double-stranded DNA containing an abasic site opposite a small gap with fpg protein generated predominantly beta-product. These data suggested that the induction of a double-strand break by fpg led to the destabilization of the protein-DNA covalent intermediate, causing the fpg protein to prematurely dissociate from the DNA substrate. Furthermore, when a double-stranded DNA containing an abasic site opposite an A was used as a substrate, K155A mutant fpg protein yielded a mixture of beta- and beta,delta-products. These data suggested that K155 is essential for maintaining the stability of the intermediary protein-DNA covalent complex. Pre-steady-state burst kinetics showed that mutation in K155 led to the apparent disappearance of the initial burst, suggesting that the rate of product release from K155A is much greater than the rate of chemical reaction catalyzed by the mutant enzyme. This is consistent with the idea that K155A dissociates prematurely from the covalent complex, leading to a higher turnover number observed for K155A for DNA substrate containing an AP site.

Quantitation of immunosuppression by tacrolimus using flow cytometric analysis of interleukin-2 and interferon-gamma inhibition in CD8(-) and CD8(+) peripheral blood T cells

The authors have determined the frequency of intracellular interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) synthesis by T-cell subsets in whole blood (WB) and isolated lymphocytes in 16 transplant recipients treated with tacrolimus and 10 control patients who were not transplant recipients. The authors also determined the impact of varying amounts of red blood cells (RBC) on immunosuppression by tacrolimus. Samples were analyzed by two-color flow cytometry, and the results were expressed as a ratio of whole blood to isolated lymphocytes. In healthy subjects who were not transplant recipients, the frequency of IL-2--producing CD8(-) and CD8(+) cells was higher in WB than in isolated lymphocytes (mean +/- SD of whole blood to lymphocytes ratio: 1.24 +/- 0.5 and 1.67 +/- 0.62, respectively). Adding varying amounts of RBC had no significant impact on IL-2 production by CD8(-) and CD8(+) T cells. Adding tacrolimus (10 ng/mL) to lymphocyte cultures inhibited (90%) IL-2 production in isolated T cells but not in the whole-blood assay. The dose of tacrolimus required for a 50% inhibition of IL-2 release in T cells was 10-fold higher in cultures with RBC than without. Peripheral blood mononuclear cells (PBMC) isolated from tacrolimus-treated whole blood (WB) showed less IL-2 inhibition than did lymphocytes in the WB. The authors also tested cytokine production in WB and PBMCs in 16 transplant recipients and observed various patterns of reactivity. The frequency of IL-2--producing CD8(-) and CD8(+) cells was similar using two different methods in 10 of 16 patients tested. By contrast, in the remaining six patients the authors observed a significant inhibition of IL-2 production in both CD8(-) and CD8(+) T-cell subsets in the whole-blood assay but not in the isolated lymphocytes. The frequency of CD8(-) IFN-gamma--producing cells was significantly lower in 9 of 16 patients, but the same individuals showed no inhibition of their CD8(+) IFN-gamma T cells. The trough levels of tacrolimus did not predict the level of cytokine inhibition in the whole-blood assay in these patients. The authors' results show that the whole-blood assay for cytokine production can be used for monitoring the in vivo effect of tacrolimus in transplant recipients.

1,2,5-Thiadiazolidin-3-one 1,1 Dioxide: A Powerful Scaffold for Probing the S′ Subsites of (Chymo)trypsin-Like Serine Proteases

The 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold (I) embodies a motif that allows it to dock to the active site of (chymo)trypsin-like proteases in a predictable and substrate-like fashion. Consequently, inhibitors derived from this heterocyclic scaffold interact with both the S and S' subsites of an enzyme. Exploitation of binding interactions with both the S and S' subsites of a target enzyme may lead to compounds with greatly enhanced enzyme selectivity and inhibitory potency. This preliminary report describes the use of a series of compounds having the heterocyclic scaffold linked to various amino acids to probe the S' subsites of human leukocyte elastase (HLE), proteinase 3 (PR 3), and cathepsin G (Cat G). For comparative purposes, a series of compounds derived from a related scaffold, isothiazolidin-3-one 1,1 dioxide (II), was also generated. Several of the compounds were found to be highly potent and selective time-dependent inhibitors of HLE, PR 3, and Cat G.

Novel approaches to the treatment of acute renal failure

Acute renal failure (ARF) occurs frequently in hospitalised patients and is associated with significant morbidity and mortality. Many therapeutic strategies have been undertaken both to prevent acute renal injury and, once ARF occurs, to improve renal function and reduce mortality. Among the available pharmacological options, no specific therapy has been shown to alter the course of ARF. This article reviews the efficacy of several strategies in experimental renal disease and raises the possibility that similar interventions might be available to the clinician in the near future for the prevention and management of ARF. The prospect of these novel strategies together with the ever-increasing understanding of the complex pathophysiology of ARF, offers the promise of effective and more physiological therapeutic interventions in this new millennium.

Characterization of a novel 8-oxoguanine-DNA glycosylase activity in Escherichia coli and identification of the enzyme as endonuclease VIII

8-Oxoguanine (G*), induced by reactive oxygen species, is mutagenic because it mispairs with A. The major G*-DNA glycosylase (OGG), namely, OGG1 in eukaryotes, or MutM in Escherichia coli, excises G* when paired in DNA with C, G, and T, but not A, presumably because removal of G* from a G*.A pair would be mutagenic. However, repair of G* will prevent mutation when it is incorporated in the nascent strand opposite A. This could be carried out by a second OGG, OGG2, identified in yeast and human cells. We have characterized a new OGG activity in E. coli and then identified it to be endonuclease VIII (Nei), discovered as a damaged pyrimidine-specific DNA glycosylase. Nei shares sequence homology and reaction mechanism with MutM and is similar to human OGG2 in being able to excise G* when paired with A (or G). Kinetic analysis of wild type Nei showed that it has significant activity for excising G* relative to dihydrouracil. The presence of OGG2 type enzyme in both E. coli and eukaryotes, which is at least as efficient in excising G* from a G*.A (or G) pair as from a G*.C pair, supports the possibility of G* repair in the nascent DNA strand.

Potent inhibition of serine proteases by heterocyclic sulfide derivatives of 1,2,5-thiadiazolidin-3-one 1,1 dioxide

The existence of subtle differences in the Sn' subsites of closely-related (chymo)trypsin-like serine proteases, and the fact that the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold docks to the active site of (chymo)trypsin-like enzymes in a substrate-like fashion, suggested that the introduction of recognition elements that can potentially interact with the Sn' subsites of these proteases might provide an effective means for optimizing enzyme potency and selectivity. Accordingly, a series of heterocyclic sulfide derivatives based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold (I) was synthesized and the inhibitory activity and selectivity of these compounds toward human leukocyte elastase (HLE), proteinase 3 (PR 3) and cathepsin G (Cat G) were then determined. Compounds with P1 = isobutyl were found to be potent, time-dependent inhibitors of HLE and, to a lesser extent PR 3, while those with P1 = benzyl inactivated Cat G rapidly and irreversibly. This study has demonstrated that 1,2,5-thiadiazolidin-3-one 1,1 dioxide-based heterocyclic sulfides are effective inhibitors of (chymo)trypsin-like serine proteases.

Utilization of the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold in the design of potent inhibitors of serine proteases: SAR studies using carboxylates

A series of carboxylate derivatives based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide and isothiazolidin-3-one 1,1 dioxide scaffolds has been synthesized and the inhibitory profile of these compounds toward human leukocyte elastase (HLE), cathepsin G (Cat G) and proteinase 3 (PR 3) was then determined. Most of the compounds were found to be potent, time-dependent inhibitors of elastase, with some of the compounds exhibiting k(inact)/K1 values as high as 4,928,300 M(-1) s(-1). The inhibitory potency of carboxylate derivatives based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide platform was found to be influenced by both the pKa and the inherent structure of the leaving group. Proper selection of the primary specificity group (R(I)) was found to lead to selective inhibition of HLE over Cat G, however, those compounds that inhibited HLE also inhibited PR 3, albeit less efficiently. The predictable mode of binding of these compounds suggests that, among closely-related serine proteases, highly selective inhibitors of a particular serine protease can be fashioned by exploiting subtle differences in their S' subsites. This study has also demonstrated that the degradative action of elastase on elastin can be abrogated in the presence of inhibitor 17.

Comparative pharmacogonostic studies of genuine and commercial samples of trianthema decandra linn

Trianthema decandra Linn. (Fam ficoidaceae) Commonly known a "Vellai sharunai'on Tamil and Punaranavi in Sanskrit the roots are used in hepatitis, asthma and suppression of menses the genuine and tree commercial samples of the root of R. Decandra in have been compared pharmacognostically for the first time in the present investigation all the pharmacognostic findings reveal adulteration in the commercial samples.

Management of quality, capacity, and productivity at Merck

Merck is one of the largest manufacturers of drugs in the world. With emphasis on research and development and quality, it invents, develops, and markets a wide variety of human and animal health products. Merck-Medco is the industry leader in managed pharmaceutical care. Merck's productivity increases are largely attributed to procurement, inventory policies, capacity initiatives, and strategic alliances.

Potent and specific inhibition of human leukocyte elastase, cathepsin G and proteinase 3 by sulfone derivatives employing the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold

This paper describes the results of structure-activity relationship studies in a series of heterocyclic mechanism-based inhibitors based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold I and capable of interacting with the Sn and Sn' subsites of a serine proteinase. Sulfone derivatives of I were found to be highly effective, time-dependent inhibitors of human leukocyte elastase (HLE), cathepsin G (Cat G) and proteinase 3 (PR 3). The judicious selection of an R1 group (accommodated at the primary specificity site S1) that is based on the known substrate specificity of a target serine proteinase, was found to yield highly selective inhibitors. The presence of a benzyl group (R2 = benzyl) at the S2 subsite was found to lead to a pronounced enhancement in inhibitory potency. Furthermore, the effective use of computer graphics and modeling has led to the design of potent, water-soluble inhibitors. The results of these studies demonstrate that the 1,2,5-thiadiazolidin-3-one 1,1, dioxide platform provides an effective means for appending recognition elements in a well-defined vector relationship, and in fashioning highly-selective and potent inhibitors of serine proteinases.

Use of the 1,2,5-thiadiazolidin-3-one 1,1 dioxide and isothiazolidin-3-one 1,1 dioxide scaffolds in the design of potent inhibitors of serine proteinases

The attachment of a phosphate leaving group to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide and isothiazolidin-3-one 1,1 dioxide scaffolds was found to yield highly potent, time-dependent inhibitors of human leukocyte elastase (HLE).

Immunogenicity study of Haemophilus influenzae type B conjugate vaccine in Indian infants

OBJECTIVE

To assess the immunogenicity in Indian infants to Haemophilus influenzae b oligosaccharide conjugate vaccine (HbOC).

DESIGN

Prospective multicenter study.

SETTING

Pediatric Out Patient Department of general hospitals in Pune and Mumbai.

SUBJECTS

124 full term healthy infants brought for routine DPT/OPV immunization.

METHODS

Infants were administered 3 doses of 0.5 ml of HbOC, on the same day as their DPT/OPV immunization, injected intramuscularly on the limb opposite to that where DPT vaccine was administered. Data on local reactions and general symptoms was collected for three days after every dose. The children had their blood collected for assay of anti PRP (polyribosil ribitol phosphate) antibody titers, along with the first injection and one month after the third injection. One hundred and three infants completed the study protocol with two blood collections.

RESULTS

The initial geometric mean titers (GMT) of 0.124 mcg/ml rose by 37 times to 4.552 mcg/ml. Ninety eight children (95.1%) had a final titer of > or = 0.15 mcg/ml, the minimum level associated with protection, and 77 children (74.8%) had a final level of > or = 1.0 mcg/ml, a level associated with long term protection.

CONCLUSION

HbOC is immunogenic in Indian infants when used as per the locally recommended DPT/OPV immunization schedule.

Structure-based design of a general class of mechanism-based inhibitors of the serine proteinases employing a novel amino acid-derived heterocyclic scaffold

We describe in this paper the structure-based design of a general class of heterocyclic mechanism-based inhibitors of the serine proteinases that embody in their structure a novel peptidomimetic scaffold (1,2,5-thiadiazolidin-3-one 1,1-dioxide). Sulfone derivatives of this class (I) were found to be time-dependent, potent, and highly efficient irreversible inhibitors of human leukocyte elastase, cathepsin G, and proteinase 3. The partition ratios for a select number of inhibitors were found to range between 0 and 1. We furthermore demonstrate that these inhibitors exhibit remarkable enzyme selectivity that is dictated by the nature of the P1 residue and is consistent with the known substrate specificity reported for these enzymes. Thus, inhibitors with small hydrophobic side chains were found to be effective inhibitors of elastase, those with aromatic side chains of cathepsin G, and those with a basic side chain of bovine trypsin. Taken together, the findings cited herein reveal the emergence of a general class of stable mechanism-based inhibitors of the serine proteinases which can be readily synthesized using amino acid precursors. Biochemical and high-field NMR studies show that the interaction of this class of inhibitors with a serine proteinase results in the formation of a stable acyl complex(es) and the release of benzenesulfinate, formaldehyde, and a low molecular weight heterocycle. The data are consistent with initial formation of a Michaelis-Menten complex, acylation of Ser195, and tandem loss of the leaving group. The initial HLE-inhibitor complex reacts with water generating formaldehyde and a stable HLE-inhibitor complex. Whether the initial HLE-inhibitor complex also reacts with His57 to form a third complex is not known at this point. The desirable salient parameters associated with this class of inhibitors, including the expeditious generation of structurally diverse libraries of inhibitors based on I, suggest that this class of mechanism-based inhibitors is of general applicability and can be used in the development of inhibitors of human and viral serine proteinases of clinical relevance.

Design, synthesis, and in vitro inhibitory activity toward human leukocyte elastase, cathepsin G, and proteinase 3 of saccharin-derived sulfones and congeners

The inhibitory activity toward human leukocyte elastase (HLE), cathepsin G (Cat G), and proteinase 3 (PR 3) of a series of saccharin derivatives having a sulfinate leaving group was investigated. The results of this study revealed that (a) inhibitory activity is dependent on the nature and pKa of the leaving group, and (b) the synthesized saccharin derivatives exhibit selective inhibition toward HLE and PR 3, with low or no activity toward cathepsin G. The results of exploratory biochemical, HPLC and high-field 13C NMR studies are also described.