Qualification of a 17β-estradiol (E2) Assay in Sprague Dawley Rat Serum

Introduction/Objective

Significant technical issues are associated with methods used for the measurement of estradiol.The objective of this study was to qualify an electrochemiluminescent (ECL) assay for the quantification of 17β-estradiol (E2) in rat serum. Hemolysis has been identified as a factor that interferes with accurate measurement.The impact of hemolysis was also assessed.

Methods

Approximately 1.0 mL of whole blood was collected from male and female rats into separate red top tubes and processed to serum.

The LoQ for E2 was evaluated by analyzing the low calibrator or at least 6 serum samples diluted to produce a value at the low end of the reportable range 8 times in the same run.The mean, standard deviation, and %CV were calculated for each sample.The data set was analyzed by plotting the data and determining the concentration at the intersection of the precision profile curve.

Linearity of dilution was performed using commercially available calibration verification material and E2 stripped rat serum.The correlation coefficient, the slope, and the % Nominal were calculated.

Intra assay precision was evaluated by analyzing 8 consecutive times in a single run one rat serum sample that was not diluted or spiked. This analysis was performed during the evaluation of the LoQ.The mean, SD and %CV were calculated.

The interference of hemolysis with the E2 assay was tested by analyzing at least 5 rat serum samples/pools spiked with hemolyzed rat serum at different hemoglobin concentrations.The %RE was calculated.

Results

The LoQ assays were acceptable. For all samples tested, the % CV was less than or equal to 25%.The LoQ was verified to be 8.50 pg/mL. The %CV was 15.6%. For samples with estradiol concentrations below the LoQ, a value of 4.25 pg/ml was reported.

Linearity of dilution for E2 was acceptable.The correlation coefficients were greater than or equal to 0.9000, the slopes were between 0.7500 and 1.2500, and the % nominals for each level were between 75-125%.

The intra-assay precision was considered acceptable with a %CV of 8.6%.

There was no hemolysis interference in the assay when samples were spiked with hemoglobin concentrations of up to 70 mg/dL, based on the %RE of less than or equal to 25% of non-hemolyzed samples.

Conclusion

Qualification of the ECL method, demonstrates the assay is suitable for the determination of E2 in serum samples from rats and absence of hemolysis interference up to 70 mg/dL of hemoglobin concentration.

Blebbistatin-Loaded Poly(d,l-lactide-co-glycolide) Particles For Treating Arthrofibrosis

Joint immobility is a debilitating complication of articular trauma that is characterized by thickening and stiffening of the joint capsule and the formation of fibrotic lesions inside joints. Capsule release surgery can temporarily restore mobility, but contraction often recurs due to the contractile activities of fibroblasts, which exert tension on the capsule ECM via nonmuscle myosin II. Based on these findings we hypothesized that blebbistatin, a drug that reversibly inhibits the activity of this protein, would relax ECM tension imposed by fibroblasts and reduce fibrosis. In this study, we characterized the effectiveness of blebbistatin as an anticontractile treatment. Given that sustained suppression of contractile activity may be required to achieve capsule release and reduce fibrosis, we compared the effects on fibroblast-mediated collagen ECM displacement of blebbistatin-loaded poly(lactide-co-gylcolide) (PLGA) particles versus bolus blebbistatin dosing. Time-lapse imaging of fluorescent microspheres embedded in collagen gels confirmed that PLGA/blebbistatin inhibited force generation and reduced both gel displacement and rate of displacement. In addition, collagen production at 10 days was significantly reduced. Taken together, these data indicate that blebbistatin-loaded PLGA particles can be used to inhibit fibroblast force-generation and reduce collagen production and lay the foundation for optimization of drug delivery technology for treating arthrofibrosis.

Undetectable pregnancy-associated plasma protein-A in antenatal serum Down's syndrome screening: a case of assay interference

Serum pregnancy-associated plasma protein-A (PAPP-A) is measured in Down's syndrome screening, routinely offered to women in pregnancy. We present the case of an undetectable pregnancy-associated plasma protein-A concentration on the PerkinElmer AutoDELFIA system where immunoassay interference was suspected. Investigations performed, including dilution and recovery studies and antibody-blocking tube incubations, all yielded serum pregnancy-associated plasma protein-A concentrations of <25 mU/L. Pregnancy-associated plasma protein-A was also undetectable on two alternative pregnancy-associated plasma protein-A assays. An experimental manual Delfia procedure suggested the site of interference was between the secondary antibody and the pregnancy-associated plasma protein-A molecule. This case of negative interference in the PerkinElmer pregnancy-associated plasma protein-A assay produced a falsely high Down's syndrome risk that might have led to an unnecessary invasive procedure with the potential for fetal loss. This highlights the need for Down's syndrome screening laboratories to be vigilant to immunoassay interference due to the significant impact of the results on patient decision outcome.

In emergently ventilated trauma patients, low end-tidal CO2 and low cardiac output are associated and correlate with hemodynamic instability, hemorrhage, abnormal pupils, and death

Background

In a smaller experience, the authors previously demonstrated that end-tidal carbon dioxide (PetCO₂) and cardiac output (CO) had a positive association in emergently intubated trauma patients during Emergency Department resuscitation. The aim of this larger study was to reassess the relationship of PetCO₂ with CO and identify patient risk-conditions influencing PetCO₂ and CO values.

Methods

The investigation consists of acutely injured trauma patients requiring emergency tracheal intubation. The study focuses on the prospective collection of PetCO₂ and noninvasive CO monitor (NICOM®) values in the Emergency Department.

Results

From the end of March through August 2011, 73 patients had 318 pairs of PetCO₂ (mm Hg) and CO (L/min.) values. Mean data included Injury Severity Score (ISS) ≥15 in 65.2%, Glasgow Coma Score of 6.4 ± 4.6, hypotension in 19.0%, and death in 34.3%. With PetCO₂ ≤ 25 (15.9 ± 8.0), systolic blood pressure was 77.0 ± 69, CO was 3.2 ± 3.0, cardiac arrest was 60.4%, and mortality was 84.9%. During hypotension, CO was lower with major blood loss (1.9), than without major loss (5.0; P = 0.0008). Low PetCO₂ was associated with low CO (P < 0.0001). Low PetCO₂ was associated (P ≤ 0.0012) with ISS > 20, hypotension, bradycardia, major blood loss, abnormal pupils, cardiac arrest, and death. Low CO was associated (P ≤ 0.0059) with ISS > 20, hypotension, bradycardia, major blood loss, abnormal pupils, cardiac arrest, and death.

Conclusions

During emergency department resuscitation, a decline in PetCO₂ correlates with decreases in noninvasive CO in emergently intubated trauma patients. Decreasing PetCO₂ and declining NICOM CO are associated with hemodynamic instability, hemorrhage, abnormal pupils, and death. The study indicates that NICOM CO values are clinically discriminate and have physiologic validity.

Assessment of Bradykinesia in Parkinson's disease patients through a multi-parametric system

The aim of this paper is to describe and present the results of the automatic detection and assessment of bradykinesia in motor disease patients using wireless, wearable accelerometers. The current work is related to a module of the PERFORM system, a FP7 project from the European Commission, that aims at providing an innovative and reliable tool, able to evaluate, monitor and manage patients suffering from Parkinson's disease. The assessment procedure was carried out through a developed C# library that detects the activities of the patient using an activity recognition algorithm and classifies the data using a Support Vector Machine trained with data coming from previous test phases. The accuracy between the output of the automatic detection and the evaluation of the clinician both expressed with the Unified Parkinson's disease Rating Scale, presents an average value of [68.3 ± 8.9]%. A meta-analysis algorithm is used in order to improve the accuracy to an average value of [74.4 ± 14.9]%. Future work will include a personalized training of the classifiers in order to achieve a higher level of accuracy.

Cytoskeletal dissolution blocks oxidant release and cell death in injured cartilage

The mechanisms by which articular surface impact causes post-traumatic osteoarthritis are not well understood, but studies of cartilage explants implicate the mitochondrial electron transport chain as a source of oxidants that cause chondrocyte death from mechanical injury. The linkage of mitochondria to the cytoskeleton suggests that they might release oxidants in response to mechanical strain, an effect that disrupting the cytoskeleton would prevent. To test this we investigated the effects of agents that promote the dissolution of microfilaments (cytochalasin B) or microtubules (nocodazole) on oxidant production and chondrocyte death following impact injury. Osteochondral explants treated with cytochalasin B or nocodazole for 4 h were impacted (7 J/cm(2)) and stained for oxidant production directly after impact and for cell viability 24 h after impact. Surfaces within and outside impact sites were then imaged by confocal microscopy. Both agents significantly reduced impact-induced oxidant release (p < 0.05); however, cytochalasin B was more effective than nocodazole (>60% reduction vs. 40% reduction, respectively). Both agents also prevented impact induced cell death. Dissolution of the cytoskeleton by both drugs was confirmed by phalloidin staining and confocal microscopy. These findings show that chondrocyte mortality from impact injury depends substantially on mitochondrial-cytoskeletal linkage, suggesting new approaches to stem mechanically induced cartilage degeneration.

Discovery of 4'-azido-2'-deoxy-2'-C-methyl cytidine and prodrugs thereof: a potent inhibitor of Hepatitis C virus replication

4'-Azido-2'-deoxy-2'-methylcytidine (14) is a potent nucleoside inhibitor of the HCV NS5B RNA-dependent RNA polymerase, displaying an EC(50) value of 1.2 μM and showing moderate in vivo bioavailability in rat (F=14%). Here we describe the synthesis and biological evaluation of 4'-azido-2'-deoxy-2'-methylcytidine and prodrug derivatives thereof.

Repeated measurement of mechanical properties in viable osteochondral explants following a single blunt impact injury

The objective of this work was to develop a method for repeated same-site measurement of mechanical properties suitable for the detection of degenerative changes in a biologically active explant model after a single blunt impact injury. Focal blunt impact injuries to articular surfaces lead to local cartilage degeneration and loss of mechanical properties. We employed a repeated measurement methodology to determine variations in mechanical same-site properties before and after injury in living cartilage, with the hypothesis that normalization with initial mechanical properties may provide a clearer evaluation of impact effects and improve our understanding of the biologic responses to impact injury. Bovine osteochondral explants were cultured for up to 14 days after impact injury. Indentation tests were performed before and after impact injury to assess relative changes in mechanical properties. Creep strain increased significantly in impacted explants after 7 days and in both impacted and control explants after 14 days. Further analysis at 14 days revealed decreases in stretch factor beta, creep time constant and local compressive modulus. A repeated measures methodology reliably detected changes in the mechanical behaviour of viable osteochondral explants after a single impact injury.

Biomechanical disc culture system: feasibility study using rat intervertebral discs

A small-scale biomechanical disc culture system was designed to stimulate intervertebral disc (IVD) 'motion segment' in culture environment with load-controlled compression and combined load (compression+shear). After 7 days of diurnal mechanical loading, cell viability of discs stimulated with static compression load (0.25 MPa) and static combined load (compression (0.25 MPa)+shear (1.5N)) were similar (>90 per cent) to unloaded controls. Mechanically stimulated discs showed decrease in static/dynamic moduli, early stress relaxation, and loss of disc height after 7 days of diurnal loading. Histological data of discs indicated load-induced transformations that were not apparent in controls. The feasibility of studying the mechanobiology of intact IVD as a motion segment was demonstrated. Media conditioning (improve tissue stability in long-term culture) and application of biochemical gene expression assays (differential tissue response to types of mechanical stimulation) are proposed as future improvements. The study suggests that the limitations in studying mechanobiology of IVD pathology in vitro can be overcome and it is possible to understand the physiologically relevant mechanism of IVD pathology.

Rotenone prevents impact-induced chondrocyte death

Mechanical insult to articular cartilage kills chondrocytes, an event that may increase the risk of posttraumatic osteoarthritis. Recent reports indicate that antioxidants decrease impact-induced chondrocyte death, but the source(s) of oxidants, the time course of oxidant release, and the identity of the oxidative species generated in response to injury are unknown. A better understanding of these processes could lead to new treatments of acute joint injuries. To that end, we studied the kinetics and distribution of oxidant production in osteochondral explants subjected to a single, blunt-impact injury. We followed superoxide production by measuring the time-dependent accumulation of chondrocyte nuclei stained with the superoxide-sensitive probe dihydroethidium. The percentage of chondrocytes that were dihydroethidium-positive was 35% above baseline 10 min after impact, and 65% above baseline 60 min after impact. Most positive cells were found within and near areas contacted directly by the impact platen. Rotenone, an electron transport chain inhibitor, was used to test the hypothesis that mitochondria contribute to superoxide release. Rotenone treatment significantly reduced dihydroethidium staining, which remained steady at 15% above baseline for up to 60 min postimpact. Moreover, rotenone reduced chondrocyte death in impact sites by more than 40%, even when administered 2 h after injury (p < 0.001). These data show that much of the acute chondrocyte mortality caused by in vitro impact injuries results from superoxide release from mitochondria, and suggest that brief exposure to free radical scavengers could significantly improve chondrocyte viability following joint injury.

The effect of incongruent instructions and consequences on imitation in retarded children

Three retarded boys served as subjects in a 13-phase experiment. In eight of these phases, the instructions administered by the experimenter before demonstrating a behavior and the consequences for imitative behavior were incongruent (the consequences were not those indicated by the instructions). Consequences rather than instructions controlled imitative behavior when (a) subjects were instructed not to imitate but received reinforcers if they imitated; (b) subjects were instructed to imitate but were differentially reinforced for other behavior; (c) subjects were instructed to imitate but were verbally reprimanded for imitation. Although subjects were highly imitative at the beginning of the study, when there was no reinforcement for imitation subjects gradually stopped imitating when instructed not to imitate. Instructions seemed to control imitative behavior when there was no reinforcement for imitation and subjects were instructed to imitate. These results indicated a need for further investigation of antecedent and consequent variables in imitation experiments and pointed out that certain techniques may be more efficient than others in eliminating well-established responses.

The design, synthesis, and antiviral activity of monofluoro and difluoro analogues of 4'-azidocytidine against hepatitis C virus replication: the discovery of 4'-azido-2'-deoxy-2'-fluorocytidine and 4'-azido-2'-dideoxy-2',2'-difluorocytidine

The discovery of 4'-azidocytidine (3) (R1479) (J. Biol. Chem. 2006, 281, 3793; Bioorg. Med. Chem. Lett. 2007, 17, 2570) as a potent inhibitor of RNA synthesis by NS5B (EC(50) = 1.28 microM), the RNA polymerase encoded by hepatitis C virus (HCV), has led to the synthesis and biological evaluation of several monofluoro and difluoro derivatives of 4'-azidocytidine. The most potent compounds in this series were 4'-azido-2'-deoxy-2',2'-difluorocytidine and 4'-azido-2'-deoxy-2'-fluoroarabinocytidine with antiviral EC(50) of 66 nM and 24 nM in the HCV replicon system, respectively. The structure-activity relationships within this series were discussed, which led to the discovery of these novel nucleoside analogues with the most potent compound, showing more than a 50-fold increase in antiviral potency as compared to 4'-azidocytidine (3).

Ultrasound-guided fine-needle aspiration versus fine-needle capillary sampling biopsy of thyroid nodules: does technique matter?

OBJECTIVE

Both fine-needle aspiration (FNA) and fine-needle capillary (FNC) sampling of palpable thyroid nodules have been advocated. The appropriate technique for biopsy of nonpalpable nodules now sampled under ultrasound guidance has not been assessed. The objective of this study was to determine cytologic adequacy rates of ultrasound-guided FNA and FNC sampling.

METHODS

Ultrasound-guided fine-needle biopsy was performed on 180 thyroid nodules. Nodules were measured and characterized (mixed cystic-solid or solid) on diagnostic sonography. The technique used for biopsy (FNA versus FNC sampling) alternated sequentially per patient. Four 25-gauge fine-needle samples were obtained from each nodule. The sampling adequacy and cytopathologic diagnoses were recorded. The significance of differences in cytologic adequacy rates between techniques was then assessed with a repeated measures logistic regression model.

RESULTS

Fine-needle aspiration and FNC sampling biopsies were performed in 88 and 92 nodules, respectively. Fine-needle aspiration was diagnostic (ie, satisfactory) in 78 (89%) of 88 nodules and nondiagnostic (less than optimal or unsatisfactory) in 10 (11%) of 88 nodules; FNC sampling was diagnostic in 80 (87%) of 92 nodules and nondiagnostic in 12 (13%) of 92 nodules. Fine-needle aspiration sampling was diagnostic in 38 (86%) of 44 solid nodules and 40 (91%) of 44 mixed cystic-solid nodules; FNC sampling was diagnostic in 48 (81%) of 59 solid nodules and 32 (97%) of 33 mixed cystic-solid nodules. These percentages were not significantly different.

CONCLUSIONS

Ultrasound-guided FNA and FNC sampling result in comparable diagnostic cytologic adequacy rates. Equivalent diagnostic yields and the technical ease of capillary sampling may prompt adoption of FNC sampling at high-volume endocrine/radiology practices.

2'-deoxy-4'-azido nucleoside analogs are highly potent inhibitors of hepatitis C virus replication despite the lack of 2'-alpha-hydroxyl groups

RNA polymerases effectively discriminate against deoxyribonucleotides and specifically recognize ribonucleotide substrates most likely through direct hydrogen bonding interaction with the 2'-alpha-hydroxy moieties of ribonucleosides. Therefore, ribonucleoside analogs as inhibitors of viral RNA polymerases have mostly been designed to retain hydrogen bonding potential at this site for optimal inhibitory potency. Here, two novel nucleoside triphosphate analogs are described, which are efficiently incorporated into nascent RNA by the RNA-dependent RNA polymerase NS5B of hepatitis C virus (HCV), causing chain termination, despite the lack of alpha-hydroxy moieties. 2'-deoxy-2'-beta-fluoro-4'-azidocytidine (RO-0622) and 2'-deoxy-2'-beta-hydroxy-4'-azidocytidine (RO-9187) were excellent substrates for deoxycytidine kinase and were phosphorylated with efficiencies up to 3-fold higher than deoxycytidine. As compared with previous reports on ribonucleosides, higher levels of triphosphate were formed from RO-9187 in primary human hepatocytes, and both compounds were potent inhibitors of HCV virus replication in the replicon system (IC(50) = 171 +/- 12 nM and 24 +/- 3 nM for RO-9187 and RO-0622, respectively; CC(50) >1 mM for both). Both compounds inhibited RNA synthesis by HCV polymerases from either HCV genotypes 1a and 1b or containing S96T or S282T point mutations with similar potencies, suggesting no cross-resistance with either R1479 (4'-azidocytidine) or 2'-C-methyl nucleosides. Pharmacokinetic studies with RO-9187 in rats and dogs showed that plasma concentrations exceeding HCV replicon IC(50) values 8-150-fold could be achieved by low dose (10 mg/kg) oral administration. Therefore, 2'-alpha-deoxy-4'-azido nucleosides are a new class of antiviral nucleosides with promising preclinical properties as potential medicines for the treatment of HCV infection.

First Example of Phosphoramidate Approach Applied to a 4‘-Substituted Purine Nucleoside (4‘-Azidoadenosine): Conversion of an Inactive Nucleoside to a Submicromolar Compound versus Hepatitis C Virus

We report on the synthesis of the anti hepatitis C virus (HCV) agent 4'-azidoadenosine (1) and the application of the phosphoramidate ProTide technology to this nucleoside. The synthesis of 1 was achieved through an epoxide intermediate followed by regio- and stereoselective ring opening by azidotrimethylsilane in the presence of a Lewis acid. Compound 1 did not inhibit HCV replication in cell culture at concentrations up to 0.1 mM. However, a submicromolar active agent could be derived from 1 by the application of the ProTide technology. All the phosphoramidates prepared were L-alanine derivatives with variations in the aryl moiety and in the ester part of the amino acid. The benzyl ester and the l-naphthyl phosphate (18) had the best activity in replicon assay. Phosphoramidates (18-21) achieved a significant improvement in antiviral potency over the parent nucleoside (1) with no increase in cytotoxicity.

[Five years of renal trauma in a paediatric trauma center: new tools in the diagnostic and therapeutic process]

INTRODUCTION

There is general agreement in the conservative management of most renal traumas, but questions like the role of angiography are still controversial. Our objective is to review the paediatric renal trauma characteristics, propose a therapeutic protocol and suggest new therapeutic tools.

MATERIAL AND METHODS

Retrospective review of clinical records (epidemiology, diagnostic methods, renal injury grade according to the AAST Organ Injury Scale, treatment and follow up) of the paediatric renal injuries at Vail d'Hebron Hospital in the last 5 years. Outline of a diagnostic-therapeutic protocol consistent with the literature.

RESULTS

Since 2001, 18 cases of paediatric renal trauma have been diagnosed. Median of age was 10 years (range 2-17). Renal injury grade was: I (4), II (5), III (4), IV (4), V (1). Main mechanisms of injury were car and motorcicle accidents (4), fall (3), bicycle (3) and sports (3). There were different severity associated injuries in 10 patients. Abdominal exploration was normal in 6 cases, and in 5 (including the grade V injury) hematuria was absent or was microscopic. Mean hematocrit and hemoglobine were 34.5% y 11.8 g/dl. Abdominal CT was performed in all cases, detecting injuries that were unnoticed with ultrasound exploration. Complications were: renal artery pseudoaneurism (1), urinoma (1), uretero-pelvic joint disruption (1), arterial hypertension (3), renal colic (1). Management was: conservative in 13 cases, angiography in 4 (2 embolizations of bleeding vessels, 1 pseudoaneurism embolization, 1 placement of endovascular stents in an injury of the arterial intima), delayed surgery in 2 (1 nefrectomy, 1 uretero-pyeloplasty). All of them received prophylactic antibiotics; 10 had self-limited fever with negative cultures. Only in 2 cases DMSA at 6 months was inferior to 20%. There were no deaths.

CONCLUSIONS

In paediatric patients, there can be severe renal injuries despite absence of hematuria and a normal physical exam and hemogram. Abdominal CT with endovenous contrast is the keystone of diagnosis, and identifies vascular injuries that might need immediate treatment, like renal ischemia. Angiography is an important tool to consider in case of persistent bleeding or renal infarctation.

Application of the Phosphoramidate ProTide Approach to 4‘-Azidouridine Confers Sub-micromolar Potency versus Hepatitis C Virus on an Inactive Nucleoside

We report the application of our phosphoramidate ProTide technology to the ribonucleoside analogue 4'-azidouridine to generate novel antiviral agents for the inhibition of hepatitis C virus (HCV). 4'-Azidouridine did not inhibit HCV, although 4'-azidocytidine was a potent inhibitor of HCV replication under similar assay conditions. However 4'-azidouridine triphosphate was a potent inhibitor of RNA synthesis by HCV polymerase, raising the question as to whether our phosphoramidate ProTide approach could effectively deliver 4'-azidouridine monophosphate to HCV replicon cells and unleash the antiviral potential of the triphosphate. Twenty-two phosphoramidates were prepared, including variations in the aryl, ester, and amino acid regions. A number of compounds showed sub-micromolar inhibition of HCV in cell culture without detectable cytotoxicity. These results confirm that phosphoramidate ProTides can deliver monophosphates of ribonucleoside analogues and suggest a potential path to the generation of novel antiviral agents against HCV infection. The generic message is that ProTide synthesis from inactive parent nucleosides may be a warranted drug discovery strategy.

Rate of acute adverse events for narrow-band UVB and Psoralen-UVA phototherapy

BACKGROUND

Ultraviolet (UV) radiation therapies are commonly used to treat a wide range of dermatological conditions. However, no published data exist regarding the rate of acute adverse events occurring within the different UV therapy modalities.

AIM

The aim of this study was to determine the rate of acute adverse events experienced by patients receiving narrow-band UVB or photochemotherapy in 3 neighboring dermatology units.

METHOD

Standardized adverse event forms from all 3 units were retrospectively analysed over a 12-month period between October 2003 and September 2004. The treatments included were narrow-band UVB and systemic, bath and hand/foot PUVA.

RESULTS

A total of 8784 treatments were given over the study period. The total number of acute adverse events recorded for all phototherapy treatments was 70 (0.8%). The rates of acute adverse events for each treatment modality were 0.6% for narrow-band UVB, 1.3% for systemic PUVA, 1.3% for bath PUVA and 0.8% for hand/foot PUVA. Adverse events were due to patient non-compliance with standard operating procedures in 15 cases (21%) and operator error in 2 (3%). Only 4 of the acute adverse events were considered to be severe, accounting for 0.05% of all treatments.

CONCLUSIONS

The rates of acute adverse events with phototherapy in this analysis were low, in particular the rate of severe adverse events. The highest rate was seen with both systemic and bath PUVA. The number of adverse events resulting from operator error was low. These published rates for adverse events associated with narrow-band UVB and PUVA may help other units when analyzing their own rate of adverse events.

Design, synthesis, and antiviral properties of 4'-substituted ribonucleosides as inhibitors of hepatitis C virus replication: the discovery of R1479

A series of 4'-substituted ribonucleoside derivatives has been prepared and evaluated for inhibition of hepatitis C virus (HCV) RNA replication in cell culture. The most potent and non-cytotoxic derivative was compound 28 (4'-azidocytidine, R1479) with an IC(50) of 1.28 microM in the HCV replicon system. The triphosphate of compound 28 was prepared and shown to be an inhibitor of RNA synthesis mediated by NS5B (IC(50)=320 nM), the RNA polymerase encoded by HCV. Data on related analogues have been used to generate some preliminary requirements for activity within this series of nucleosides.

Antioxidants block cyclic loading induced chondrocyte death

Articular cartilage in congruous joints benefits from the moderate stresses and strains associated with normal cyclic loading. However, loading of joints with surface incongruities can lead to local stress and strain elevation at "step-off' sites where cartilage is not fully buttressed b ysurrounding matrix. Excessive stresses and strains predicted to occur at such sites may induce apoptosis, a process thought to promote cartilage degeneration and osteoarthritis (OA) through chondrocyte attrition. We hypothesized that the induction of apoptosis is mediated by oxidants, and that antioxidants can reduce elevated stress-induced chondrocyte attrition. To test this we exposed cylindrical cartilage explants from human articular cartilage to radially unconfined cyclic axial compression (3600 cycles, 1 Hz, 50% duty cycle) using two different physiologic loads (2MPa and 5 MPa). We found that 30% of chondrocytes in the superficial zone died within 24 hours of exposure to loading with 5 MPa axial compression, whereas mortality was limited to less than 15% with 2 MPa axial compression. Similarly, lactate accumulation in the medium was suppressed by compression with 5 MPa, but not 2 MPa. Approximately 80% of cell death induced by 5 MPa compression was blocked by pre-incubation of the explants in a variety of anti-oxidants including vitamin E, n-acetyl cysteine (NAC), and a superoxide dismutase mimetic (SOD). SOD and NAC also prevented the suppression of lactate secretion after 5 MPa compression. These observations support the hypothesis that the harmful effects of abnormal cyclic loading are mediated by oxidants and suggest that treatments to prevent OA may include methods of minimizing oxidative damage to chondrocytes.

Post-traumatic osteoarthritis: the role of stress induced chondrocyte damage

Post-traumatic osteoarthritis is the form of osteoarthritis (OA) that develops following joint injury. Although its end-stage is indistinguishable from idiopathic OA, many patients with post-traumatic OA are younger than those with idiopathic OA, and they have a well-defined precipitating insult. Clinical and experimental studies suggest that excessive acute impact energy or chronic mechanical overload cause the degeneration of the articular surface responsible for post-traumatic OA. Yet, the mechanisms by which excessive mechanical force causes OA remain unknown. For these reasons it has not been possible to develop effective methods of preventing or decreasing the risk of post-traumatic OA. We hypothesized that mechanical loading that exceeds the tolerance of the articular surface causes chondrocyte damage due to oxidative stress. Our in vitro tests of human articular cartilage samples showed that shear stress causes chondrocyte death and that anti-oxidants decrease the shear stress induced cell death. These observations suggest that specific patterns of loading are particularly damaging to articular surfaces and that improved treatments of joint injuries may include mechanical methods of minimizing shear stresses and biologic methods of minimizing oxidative damage.

What can adaptive optics do for a scanning laser ophthalmoscope ?

By compensating for the aberrations in the eye that cause blur, the adaptive optics scanning laser ophthalmoscope (AOSLO) yields high-magnification, high-resolution, real-time images of the living human retina. Features as small as single cone photoreceptors can be resolved, single leukocytes are recorded in real time as they pass through the smallest retinal capillaries, and the optical sectioning capability can be used to visualize independent layers of the retinal tissue ranging from the nerve fiber layer, through the blood vessels to the photoreceptors. The use of AO technology not only enhances the breadth of applications of conventional SLOs, but it facilitates a host of new applications. Here we provide an overview of AOSLO performance and its applications, including two clinical examples. Finally, we preview two novel applications; one where the AOSLO is used to present AO-corrected stimuli directly onto the retina while simultaneously recording their exact retinal position, and a second application where AOSLO videos are used to provide very precise, high-frequency measures of eye movements.

Percutaneous Ultrasound-Guided Pancreas Allograft Biopsy: A Single-Center Experience

Percutaneous ultrasound-guided pancreas allograft biopsy is the preferred technique for evaluating pancreas allograft rejection. Experience from large centers has shown it to be safe and effective. We report our experience with 120 percutaneous allograft biopsies performed at a single center. Biopsy tissue was obtained in 54 patients. Thirty-three patients received simultaneous pancreas and kidney transplants, 14 received isolated pancreas transplants, and 7 received a pancreas transplant after kidney transplantation. Biopsies were performed by pancreas transplantation surgeons with the assistance of radiologists under ultrasound guidance using an Acuson XP 128/10 ultrasound machine. One hundred twenty allograft biopsies were performed in 54 patients. Twenty-seven (50%) patients underwent multiple biopsies. In 102 (85%) biopsies the specimens were adequate for examination. Eighteen (15%) biopsy samples had no pancreatic tissue and showed surrounding fat and small bowel. 1 (1.8%) patient bleeding developed that required transfusion of 3 units of packed red blood cells, but no surgical intervention was necessary. One (1.8%) patient had a pancreatic fistula, which healed with nonoperative management. Biochemical evidence of pancreatitis was noted in 5 (9.2%) patients, but none of these patients had clinical signs of pancreatitis. Percutaneous ultrasound-guided pancreas allograft biopsy is a safe procedure with a low complication rate and a high tissue yield for histopathologic examination.

The novel nucleoside analog R1479 (4'-azidocytidine) is a potent inhibitor of NS5B-dependent RNA synthesis and hepatitis C virus replication in cell culture

Hepatitis C virus (HCV) polymerase activity is essential for HCV replication. Targeted screening of nucleoside analogs identified R1479 (4'-azidocytidine) as a specific inhibitor of HCV replication in the HCV subgenomic replicon system (IC(50) = 1.28 microM) with similar potency compared with 2'-C-methylcytidine (IC(50) = 1.13 microM). R1479 showed no effect on cell viability or proliferation of HCV replicon or Huh-7 cells at concentrations up to 2 mM. HCV replicon RNA could be fully cleared from replicon cells after prolonged incubation with R1479. The corresponding 5'-triphosphate derivative (R1479-TP) is a potent inhibitor of native HCV replicase isolated from replicon cells and of recombinant HCV polymerase (NS5B)-mediated RNA synthesis activity. R1479-TP inhibited RNA synthesis as a CTP-competitive inhibitor with a K(i) of 40 nM. On an HCV RNA-derived template substrate (complementary internal ribosome entry site), R1479-TP showed similar potency of NS5B inhibition compared with 3'-dCTP. R1479-TP was incorporated into nascent RNA by HCV polymerase and reduced further elongation with similar efficiency compared with 3'-dCTP under the reaction conditions. The S282T point mutation in the coding sequence of NS5B confers resistance to inhibition by 2'-C-MeATP and other 2'-methyl-nucleotides. In contrast, the S282T mutation did not confer cross-resistance to R1479.

Peristomal allergic contact dermatitis - case report and review of the literature

Allergic contact dermatitis (ACD) is a rare cause of peristomal skin problems. Only 23 cases have previously been reported in the literature. We report the case of a colostomy patient with a severe disabling blistering peristomal dermatitis. Patch testing to a British Contact Dermatitis Society standard series, medicaments and a plastics and glues series was negative. Patch testing to the patient's own products gave a positive reaction (+) at D2 and D4 to Dansac soft paste and Stomahesive paste. Further patch testing to the components of Dansac soft paste showed a positive (+) reaction at D2 and D4 to ester of polymethyl vinyl/maleic acid copolymer (Gantrez-ES) only. This is the first reported case of ACD due to Dansac soft paste. ACD to Gantrez has previously been reported but in different products. We also review the other previously reported cases of ACD causing peristomal dermatitis and stress the importance of patch testing in these cases, in particular to the patient's own products, as avoidance of identified allergens can have a large impact on the quality of life.

'Black henna' tattoos: an occult source of natural rubber latex allergy?

Temporary 'black henna' tattoos are an increasingly popular body decoration with a growing incidence of associated adverse events. We report the case of a 14 year old girl presenting with an acute allergic contact dermatitis to hair dyes. Some years previously she had a 'black henna' tattoo with prior application of a tacky transfer to the skin to outline the design followed some days later by an acute localised blistering reaction. Patch testing to an extended British Contact Dermatitis Society standard series showed relevant positive reactions to paraphenlyenediamine (PPD) and thiuram mix, as well as to several of the azo disperse dyes. We went on to perform prick testing to natural rubber latex (NRL), showing a positive reaction to the commercial HEP 100 concentration. We propose that through the initial acute reaction caused by PPD in the 'black henna' our patient was not only sensitized to PPD, but also to thiuram and natural rubber latex which may have been present in the tacky transfer applied prior to 'tattooing.' We would add that temporary 'black henna' tattoos may have more important consequences than previously thought on patients' future health by sensitization to NRL.

HIV infection presenting with duodenal tuberculosis

Extrapulmonary tuberculosis is a protean and often difficult to recognise infection. Gastrointestinal tuberculosis is a rare condition that mainly occurs in immunodeficient people. We report a case of duodenal tuberculosis, which presented with gastrointestinal symptoms, anaemia and hyponatraemia, in a patient with previously undiagnosed HIV infection.

Seventeen-year survivorship analysis of silastic metacarpophalangeal joint replacement

We reviewed the records and radiographs of 381 patients with rheumatoid arthritis who had undergone silastic metacarpophalangeal joint replacement during the past 17 years. The number of implants was 1336 in the course of 404 operations. Implant failure was defined as either revision or fracture of the implant as seen on radiography. At 17 years, the survivorship was 63%, although on radiographs two-thirds of the implants were seen to be broken. Factors which improved survival included soft-tissue balancing, crossed intrinsic transfer and realignment of the wrist. Surgery to the thumb and proximal interphalangeal joint had a deleterious effect and the use of grommets did not protect the implant from fracture.

Rheumatoid papules treated with dapsone

A patient with a long history of seropositive rheumatoid arthritis presented with a progressive papular eruption on the trunk. A skin biopsy showed a neutrophilic and palisaded granulomatous dermatitis compatible with rheumatoid papules. The eruption failed to respond to topical and systemic corticosteroids and the patient was treated with dapsone with complete resolution of the rash. Rheumatoid papules are a rare disorder seen in a variety of collagen vascular diseases. The literature concerning the treatment of rheumatoid papules is scanty. In this patient, dapsone was an effective treatment.

Two-metal ion mechanism of RNA cleavage by HIV RNase H and mechanism-based design of selective HIV RNase H inhibitors

Human immunodeficiency virus (HIV) RNase H activity is essential for the synthesis of viral DNA by HIV reverse transcriptase (HIV-RT). RNA cleavage by RNase H requires the presence of divalent metal ions, but the role of metal ions in the mechanism of RNA cleavage has not been resolved. We measured HIV RNase H activity associated with HIV-RT protein in the presence of different concentrations of either Mg2+, Mn2+, Co2+ or a combination of these divalent metal ions. Polymerase-independent HIV RNase H was similar to or more active with Mn2+ and Co2+ compared with Mg2+. Activation of RNase H by these metal ions followed sigmoidal dose-response curves suggesting cooperative metal ion binding. Titration of Mg2+-bound HIV RNase H with Mn2+ or Co2+ ions generated bell-shaped activity dose-response curves. Higher activity could be achieved through simultaneous binding of more than one divalent metal ion at intermediate Mn2+ and Co2+ concentrations, and complete replacement of Mg2+ occurred at higher Mn2+ or Co2+ concentrations. These results are consistent with a two-metal ion mechanism of RNA cleavage as previously suggested for a number of polymerase-associated nucleases. In contrast, the structurally highly homologous RNase HI from Escherichia coli is most strongly activated by Mg2+, is significantly inhibited by submillimolar concentrations of Mn2+ and most probably cleaves RNA via a one-metal ion mechanism. Based on this difference in active site structure, a series of small molecule N-hydroxyimides was identified with significant enzyme inhibitory potency and selectivity for HIV RNase H.

Activity of the isolated HIV RNase H domain and specific inhibition by N-hydroxyimides

This report describes a procedure to generate enzymatically active, isolated HIV RNase H domain. In contrast to previously described preparations, the RNA cleavage activity of the untagged RNase H domain was surprisingly similar to that of the full-length HIV-RT protein. Signature cleavages at 18 and 9 nucleotides downstream of a recessed RNA 5'-end were retained with the isolated RNase H domain. Activity was strongly decreased by deletion of 3 amino acids from the C-terminus, consistent with an important structural or functional role of the C-terminal alpha-helix. A prototype N-hydroxyimide (2-hydroxy-4H-isoquinoline-1,3-dione) was found to inhibit the activity of the isolated HIV RNase H domain as well as the RNase H activity of full-length HIV reverse transcriptase. In contrast, the compound did not significantly inhibit the structurally closely related Escherichia coli RNase HI. Specific binding of N-hydroxyimide compounds to the isolated RNase H domain was observed by protein fluorescence quenching.

Use of a pharmacophore model to discover a new class of influenza endonuclease inhibitors

Data from both our own and literature studies of the biochemistry and inhibition of influenza virus endonuclease was combined with data on the mechanism of action and the likely active site mechanism to propose a pharmacophore. The pharmacophore was used to design a novel structural class of inhibitors, some of which were found to have activities similar to that of known influenza endonuclease inhibitors and were also antiviral in cell culture.

The role of tenascin-C in adaptation of tendons to compressive loading

Although most tendon regions are subjected primarily to high tensile loads, selected regions, primarily those that directly contact bones that change the direction of the tendon, must withstand high compressive loads as well. Compressed tendon regions differ from regions subjected to primarily tensile loads: they have a fibrocartilaginous structure with spherical cells surrounded by a matrix containing aggrecan and collagen types I and II, in contrast regions not exposed to compression have a fibrous structure with spindle shaped fibroblasts surrounded by a matrix of dense, longitudinally oriented type I collagen fibrils. The spherical shape of cells in fibrocartilagenous regions indicates these cells are more loosely attached to the matrix than their spindle-shaped counterparts in fibrous regions, a feature that may help to minimize cell deformation during tendon compression. We hypothesized that expression of tenascin-C, an anti-adhesive protein, is part of the adaptation of tendon cells to compression that helps establish and maintain fibrocartilaginous regions. To test this hypothesis we compared tenascin-C content and expression in compressed (distal) versus uncompressed (proximal) segments of bovine flexor tendons. Immunohistochemistry and immunoblot analyses showed that tenascin-C content was increased in the distal tendon where it co-distributed with type II collagen and aggrecan. Tendon cells from the distal segments expressed more tenascin-C than did cells from the proximal segments for up to four days in cell culture, indicating that increased tenascin-C expression is a relatively stable feature of the distal cells. These observations support the hypothesis that tenascin-C expression is a cellular adaptation to compression that helps establish and maintain fibrocartilagenous regions of tendons.

Osteochondral repair of primate knee femoral and patellar articular surfaces: implications for preventing post-traumatic osteoarthritis

The risk of post-traumatic osteoarthritis following an intra-articular fracture is determined to large extent by the success or failure of osteochondral repair. To measure the efficacy of osteochondral repair in a primate and determine if osteochondral repair differs in the patella (PA) and the medial femoral condyle (FC) and if passive motion treatment affects osteochondral repair, we created 3.2 mm diameter 4.0 mm deep osteochondral defects of the articular surfaces of the PA and FC in both knees of twelve skeletally mature cynomolgus monkeys. Defects were treated with intermittent passive motion (IPM) or cast-immobilization (CI) for two weeks, followed by six weeks of ad libitum cage activity. We measured restoration of the articular surface, and the volume, composition, type II collagen concentration and in situ material properties of the repair tissue. The osteochondral repair response restored a mean of 56% of the FC and 34% of the PA articular surfaces and filled a mean of 68% of the chondral and 92% of the osseous defect volumes respectively. FC defect repair produced higher concentrations of hyaline cartilage (FC 83% vs. PA 52% in chondral defects and FC 26% vs. PA 14% in osseous defects) and type II collagen (FC 84% vs. PA 71% in chondral defects and FC 37% vs. PA 9% in osseous defects) than PA repair. IPM did not increase the volume of chondral or osseous repair tissue in PA or FC defects. In both PA and FC defects, IPM stimulated slightly greater expression of type II collagen in chondral repair tissue (IPM 81% vs. CI 74%); and, produced a higher concentration of hyaline repair tissue (IPM 62% vs. CI 42%), but IPM produced poorer restoration of PA articular surfaces (IPM 23% vs. CI 45%). Normal articular cartilage was stiffer, and had a larger Poisson's ratio and less permeability than repair cartilage. Overall Cl treated repair tissue was stiffer and less permeable than IPM treated repair tissue. The stiffness, Poisson's ratio and permeability of femoral condyle cast immobilized (FC CI) treated repair tissue most closely approached the normal values. The differences in osteochondral repair between FC and PA articular surfaces suggest that the mechanical environment strongly influences the quality of articular surface repair. Decreasing the risk of post-traumatic osteoarthritis following intra-articular fractures will depend on finding methods of promoting the osteochondral repair response including modifying the intra-articular biological and mechanical environments.

Co-localization of insulin-like growth factor binding protein 3 and fibronectin in human articular cartilage

OBJECTIVE

The anabolic cytokine insulin-like growth factor I (IGF-I) stimulates chondrocyte synthesis of matrix macromolecules and several lines of evidence suggest that it has a major role in maintaining articular cartilage and possibly in cartilage repair. Despite the apparent importance of IGF-I in articular cartilage metabolism and its potential importance in joint diseases, little is known about the regulation of IGF-I activity within the tissue. Insulin-like growth factor binding proteins (IGFBPs) bind IGF-I and can modify its activity. At least three IGFBPs are expressed by chondrocytes: IGFBP-3, -4 and -5. Localization of IGFPBs in the articular cartilage extracellular matrix (ECM) could create reservoirs of IGF-I within the articular cartilage ECM and thereby regulate local IGF-I levels. We hypothesized that ECM molecules bind and concentrate IGFPBs in the pericellular/territorial matrix.

DESIGN

Semi-quantitative immunohistological measures of co-localization were used to compare the spatial distribution of IGFBP-3, -4, and -5 with the distributions of three peri-cellularly-enriched matrix molecules fibronectin, tenascin-C, and type VI collagen in osteoarthritic and non-osteoarthritic human articular cartilage. Purified proteins were used in an agarose diffusion assay to compare IGFBP-3 binding to the same three matrix proteins.

RESULTS

IGFBP-3 associated with fibronectin in the pericellular/territorial matrix (approximately 40% co-localization) but not with tenascin-C, or type VI collagen (approximately 6% and approximately 15% co-localization respectively, P< 0.05). Neither IGFBP-4, nor IGFBP-5 were associated with any of the three ECM proteins (P< 0.05). In agarose diffusion assays IGFBP-3 interacted with fibronectin and heparan sulfate proteoglycan but not with type VI collagen or tenascin-C.

CONCLUSIONS

Direct binding between purified IGFBP-3 and fibronectin and the strong co-localization the two proteins in the cartilage matrix support the hypothesis that IGFPB-3 and fibronectin help regulate local IGF-I levels.

Cluster ions derived from sodium and potassium tetrafluoroborate and their collision induced dissociation in an ion trap mass spectrometer

Electrospray ionization was used to produce distributions of gas-phase cluster ions from solutions of sodium and potassium tetrafluoroborate. The majority of the cluster species followed the trend (MBF(4))(n)M(+), where M=Na and K. The values of n, for both salts, ranged from 1-15. Collision induced dissociation (MS/MS and MS(n)) in an ion trap mass spectrometer was used to determine the dissociation pathways for the cluster ions. The (NaBF(4))(n)Na(+) cluster ions fragmented via two pathways: (a) the loss of one or multiple neutral BF(3) molecules and (b) the loss of one or more NaBF(4) units. Of the two, the product ions corresponding to the loss of BF(3) units were more prominent. Unlike the Na salt, the (KBF(4))(n)K(+) cluster ions decomposed primarily by the loss of one or multiple KBF(4) units. Similar differences in dissociation behavior were observed when the heated transfer capillary, normally used to desolvate ions, was used to investigate cluster ion stability to thermal degradation and dissociation. The dissociation profiles (decrease in ion abundance with increasing activation amplitude) for several (NaF)(n)Na(+) and (KF)(n)K(+) cluster ions were measured and compared to probe the influence of the relative stability of the alkali fluorides (NaF and KF) on the dissociation behavior exhibited by the tetrafluoroborate cluster distributions. We found that the (NaF)(n)Na(+) cluster ions required higher activation amplitudes to induce fragmentation than the corresponding (KF)(n)K(+) species, indicative of stronger ionic bonding and higher gas-phase stability for the former. This in turn indicates that the reaction pathway involving only the loss of one or multiple units of BF(3), favored for the (NaBF(4))(n)Na(+) cluster series, but not for the analogous (KBF(4))(n)K(+) series, may be due to the high gas-phase stability of NaF, and relatively lower stability of KF, towards dissociation.

Training general practitioners in flexible sigmoidoscopy to screen for colorectal cancer

BACKGROUND

A screening programme to detect polyps or early carcinoma would significantly reduce the mortality and morbidity of colorectal cancer (CRC). The aims of the present study were to evaluate: (i) the feasibility of training general practitioners in flexible sigmoidoscopy (FS) for CRC screening; (ii) the acceptability of screening by faecal occult blood testing (FOBT) and FS in asymptomatic standard risk Australians aged over 50 years; and (iii) the yield of such screening.

METHODS

Subjects were recruited by general practitioner (GP) referral, newspaper advertisement or by a direct approach to retirement villages. Participants were mailed a FOBT kit and a prescreening questionnaire. Flexible sigmoidoscopy was performed by a GP supervised by an experienced endoscopist. Subjects then completed a second questionnaire. General practitioners were assessed after 50 unassisted procedures.

RESULTS

A total of 264 individuals contacted the study coordinator; 169 were screened. Screening was accepted well by the participants. Fifteen per cent of subjects had polyps and 4% had a positive FOBT. Training in FS was adversely affected by the availability of resources. Three GPs completed 50 unassisted procedures over a 15-month period, but none were able to reliably assess the distal bowel.

CONCLUSIONS

Although the three trainees and their supervisors did not consider that the GPs were adequately trained after 50 unassisted procedures, training was adversely affected by limited resources within the Victorian public hospital system. Screening by FOBT and FS was considered to be acceptable by the patients undergoing these procedures. Existing facilities are not adequate if GPs are to be trained in FS as part of a national CRC screening program.