Pyrrolopyrimidine Bumped Kinase Inhibitors for the Treatment of Cryptosporidiosis

Bumped kinase inhibitors (BKIs) that target Cryptosporidium parvum calcium-dependent protein kinase 1 have been well established as potential drug candidates against cryptosporidiosis. Recently, BKI-1649, with a 7H-pyrrolo[2,3-d]pyrimidin-4-amine, or "pyrrolopyrimidine", central scaffold, has shown improved efficacy in mouse models of Cryptosporidium at substantially reduced doses compared to previously explored analogs of the pyrazolopyrimidine scaffold. Here, two pyrrolopyrimidines with varied substituent groups, BKI-1812 and BKI-1814, were explored in several in vitro and in vivo models and show improvements in potency over the previously utilized pyrazolopyrimidine bumped kinase inhibitors while maintaining equivalent results in other key properties, such as toxicity and efficacy, with their pyrazolopyrimidine isosteric counterparts.

Mechanical and structural characterisation of the dural venous sinuses

The dural venous sinuses play an integral role in draining venous blood from the cranial cavity. As a result of the sinuses anatomical location, they are of significant importance when evaluating the mechanopathology of traumatic brain injury (TBI). Despite the importance of the dural venous sinuses in normal neurophysiology, no mechanical analyses have been conducted on the tissues. In this study, we conduct mechanical and structural analysis on porcine dural venous sinus tissue to help elucidate the tissues’ function in healthy and diseased conditions. With longitudinal elastic moduli values ranging from 33 to 58 MPa, we demonstrate that the sinuses exhibit higher mechanical stiffness than that of native dural tissue, which may be of interest to the field of TBI modelling. Furthermore, by employing histological staining and a colour deconvolution protocol, we show that the sinuses have a collagen-dominant extracellular matrix, with collagen area fractions ranging from 84 to 94%, which likely explains the tissue’s large mechanical stiffness. In summary, we provide the first investigation of the dural venous sinus mechanical behaviour with accompanying structural analysis, which may aid in understanding TBI mechanopathology.

Refinement of the rodent pentylenetetrazole proconvulsion assay, which is a good predictor of convulsions in repeat-dose toxicology studies

INTRODUCTION

The pentylenetetrazole (PTZ)-induced seizure assay in rodents is an established method for investigating drug-induced alterations in seizure threshold such as proconvulsant effects. The standard procedure in our laboratory was to administer the test item prior to 75-120 mg/kg subcutaneous PTZ. However, this dose range is associated with a high incidence of mortality, including approximately 40% or greater deaths of control animals.

METHODS

The predictivity of the PTZ-induced seizure assay was retrospectively evaluated by relating drug plasma levels associated with proconvulsant effects to exposures observed during convulsions in repeat-dose toxicology studies. Margins to estimated efficacious doses were also considered. To investigate potential refinements, a high PTZ dose (80 mg/kg, subcutaneously) was compared to two lower doses (40 and 60 mg/kg), and a range of doses of theophylline was orally administered as positive control.

RESULTS

The PTZ-induced proconvulsion assay proved to be a good predictor of convulsions in toxicology studies. In the refinement study, theophylline potentiated PTZ-induced seizures over all doses tested. At 60 mg/kg PTZ, the proconvulsant dose-dependency of theophylline was best observed. At both 40 and 60 mg/kg PTZ, mortality in control animals was significantly reduced.

DISCUSSION

Risk assessment at an early stage of drug development supports candidate selection and, along that approach, the PTZ proconvulsion assay was proven to be a good predictor of convulsions in subsequent toxicology studies. It was also demonstrated that a relatively lower PTZ dose (60 mg/kg) improved the dose-response-curve of the positive control tested, decreased mortality overall and, therefore, contributes to refining this standard procedure for CNS safety evaluation.

Increased stress associated with head-out plethysmography testing can exacerbate respiratory effects and lead to mortality in rats

INTRODUCTION

DSM421, a dihydroorotate dehydrogenase inhibitor, was in preclinical development as a potential treatment option for malaria. When tested in a core battery of safety pharmacology assays, DSM421 did not produce any effects at oral doses up to 750 mg/kg in an Irwin test in rats, but a respiratory study in rats using head-out plethysmography resulted in substantial changes in respiratory function as well as moribundity and mortality at that and lower doses. An investigation was performed to determine the source of this discrepancy.

METHODS

Potential testing errors, differences in types of plethysmography testing chambers, effects on stress indicators, and off-target activity were investigated.

RESULTS

Respiratory changes and toxicity (resulting in euthanasia in extremis) were confirmed in a repeat, head-out plethysmography test, but the effects of DSM421 were much less severe overall when the rats were tested in whole-body chambers. Additionally, at the end of the 5-h post-dosing respiratory monitoring periods, levels of stress-related hormones (particularly corticosterone) were higher overall in the head-out, than in the whole-body, tested rats. Furthermore, DSM421 was found to produce changes in cardiovascular function in unrestrained rats, and it was shown to have off-target binding affinity at the adenosine A₃ receptor (which is associated with bronchoconstriction).

DISCUSSION

The generalized stress inherent to head-out plethysmography testing exacerbated the respiratory effects of DSM421 and was possibly compounded by DSM421's cardiovascular effects, thus artifactually resulting in moribundity and mortality in rats. Care should be taken when choosing whether to use head-out versus whole-body plethysmography chambers during respiratory function testing in animals.

Screening Strategies and Methods for Better Off-Target Liability Prediction and Identification of Small-Molecule Pharmaceuticals

Pharmaceutical discovery and development is a long and expensive process that, unfortunately, still results in a low success rate, with drug safety continuing to be a major impedance. Improved safety screening strategies and methods are needed to more effectively fill this critical gap. Recent advances in informatics are now making it possible to manage bigger data sets and integrate multiple sources of screening data in a manner that can potentially improve the selection of higher-quality drug candidates. Integrated screening paradigms have become the norm in Pharma, both in discovery screening and in the identification of off-target toxicity mechanisms during later-stage development. Furthermore, advances in computational methods are making in silico screens more relevant and suggest that they may represent a feasible option for augmenting the current screening paradigm. This paper outlines several fundamental methods of the current drug screening processes across Pharma and emerging techniques/technologies that promise to improve molecule selection. In addition, the authors discuss integrated screening strategies and provide examples of advanced screening paradigms.

Advances in bumped kinase inhibitors for human and animal therapy for cryptosporidiosis

Improvements have been made to the safety and efficacy of bumped kinase inhibitors, and they are advancing toward human and animal use for treatment of cryptosporidiosis. As the understanding of bumped kinase inhibitor pharmacodynamics for cryptosporidiosis therapy has increased, it has become clear that better compounds for efficacy do not necessarily require substantial systemic exposure. We now have a bumped kinase inhibitor with reduced systemic exposure, acceptable safety parameters, and efficacy in both the mouse and newborn calf models of cryptosporidiosis. Potential cardiotoxicity is the limiting safety parameter to monitor for this bumped kinase inhibitor. This compound is a promising pre-clinical lead for cryptosporidiosis therapy in animals and humans.

Preclinical abuse liability assessment of ABT-126, an agonist at the α7 nicotinic acetylcholine receptor (nAChR)

ABT-126 is a nicotinic acetylcholine receptor (nAChR) agonist that is selective for the α7 subtype of the receptor. nAChRs are thought to play a role in a variety of neurocognitive processes and have been a pharmacologic target for disorders with cognitive impairment, including schizophrenia and Alzheimer's disease. As part of the preclinical safety package for ABT-126, its potential for abuse was assessed. While the involvement of the α4β2 subtype of the nicotinic receptor in the addictive properties of nicotine has been demonstrated, the role of the α7 receptor has been studied much less extensively. A number of preclinical assays of abuse potential including open-field, drug discrimination and self-administration were employed in male rats. ABT-126 had modest effects on locomotor activity in the open-field assay. In nicotine and d-amphetamine drug discrimination assays, ABT-126 administration failed to produce appreciable d-amphetamine-like or nicotine-like responding, suggesting that its interoceptive effects are distinct from those of these drugs of abuse. In rats trained to self-administer cocaine, substitution with ABT-126 was similar to substitution with saline, indicating that it lacks reinforcing effects. No evidence of physical dependence was noted following subchronic administration. Overall, these data suggest that ABT-126 has a low potential for abuse. Together with other literature on this drug class, it appears that drugs that selectively activate α7 nAChRs are not likely to result in abuse or dependence.

Potential functional and pathological side effects related to off-target pharmacological activity

Most pharmaceutical companies test their discovery-stage proprietary molecules in a battery of in vitro pharmacology assays to try to determine off-target interactions. During all phases of drug discovery and development, various questions arise regarding potential side effects associated with such off-target pharmacological activity. Here we present a scientific literature curation effort undertaken to determine and summarize the most likely functional and pathological outcomes associated with interactions at 70 receptors, enzymes, ion channels and transporters with established links to adverse effects. To that end, the scientific literature was reviewed using an on-line database, and the most commonly reported effects were summarized in tabular format. The resultant table should serve as a practical guide for research scientists and clinical investigators for the prediction and interpretation of adverse side effects associated with molecules interacting with components of this screening battery.

The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients

NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

Translational Biomarkers of Neurotoxicity: A Health and Environmental Sciences Institute Perspective on the Way Forward

Neurotoxicity has been linked to a number of common drugs and chemicals, yet efficient and accurate methods to detect it are lacking. There is a need for more sensitive and specific biomarkers of neurotoxicity that can help diagnose and predict neurotoxicity that are relevant across animal models and translational from nonclinical to clinical data. Fluid-based biomarkers such as those found in serum, plasma, urine, and cerebrospinal fluid (CSF) have great potential due to the relative ease of sampling compared with tissues. Increasing evidence supports the potential utility of fluid-based biomarkers of neurotoxicity such as microRNAs, F₂-isoprostanes, translocator protein, glial fibrillary acidic protein, ubiquitin C-terminal hydrolase L1, myelin basic protein, microtubule-associated protein-2, and total tau. However, some of these biomarkers such as those in CSF require invasive sampling or are specific to one disease such as Alzheimer’s, while others require further validation. Additionally, neuroimaging methodologies, including magnetic resonance imaging, magnetic resonance spectroscopy, and positron emission tomography, may also serve as potential biomarkers and have several advantages including being minimally invasive. The development of biomarkers of neurotoxicity is a goal shared by scientists across academia, government, and industry and is an ideal topic to be addressed via the Health and Environmental Sciences Institute (HESI) framework which provides a forum to collaborate on key challenging scientific topics. Here we utilize the HESI framework to propose a consensus on the relative potential of currently described biomarkers of neurotoxicity to assess utility of the selected biomarkers using a nonclinical model.

Diastolic Mitral Regurgitation in a Patient With Complex Native Mitral and Aortic Valve Endocarditis: A Rare Phenomenon With Potential Catastrophic Consequences

Diastolic mitral valve regurgitation is a rare phenomenon described in patients with atrioventricular conduction abnormalities, severe left ventricular systolic or diastolic dysfunction with regional wall motion dyssynchrony, or severe acute aortic valve regurgitation. The presence of diastolic mitral valve regurgitation in acute aortic regurgitation due to endocarditis suggests critical severity requiring urgent surgical valve replacement. We describe a case of diastolic mitral regurgitation in the setting of complex native mitral-aortic valve endocarditis in a patient in normal sinus rhythm and review the etiologic mechanisms of this phenomenon, echocardiographic assessment, and therapeutic implications for hemodynamic management.

The incidence of vasoplegia in adult patients with right-sided congenital heart defects undergoing cardiac surgery and the correlation with serum vasopressin concentrations

BACKGROUND

In adults with right-sided congenital heart disease, vasoplegia during and after cardiopulmonary bypass appears to be a frequent complication. The incidence of vasoplegia in the general adult and pediatric cardiac surgical population has been investigated, but the incidence in adult patients with right-sided congenital heart disease is unknown. Perioperative vasopressin levels during cardiac surgery have been studied in other cardiac surgical patients, but are not known in adults with right-sided congenital heart disease. The purpose of this study was to investigate the incidence of vasoplegia in adult patients undergoing right-sided cardiac surgical procedures requiring cardiopulmonary bypass and to determine the vasopressin response to cardiac surgery in this population.

METHODS

Twenty patients were enrolled and demographic, hemodynamic, cardiopulmonary bypass, and use of vasoactive medication data were collected. In addition, perioperative serum vasopressin levels were measured. Sixty adult patients undergoing left-sided cardiac surgery served as controls.

RESULTS

The incidence of vasoplegia in the control patients was 10% and the incidence in the adult patients with right-sided congenital heart disease was 20%. Vasopressin levels were low at baseline (0.5 ± 0.5 pg/mL), increased slightly after induction of anesthesia (0.6 ± 0.6 pg/mL), increased after initiation of cardiopulmonary bypass (99.7 ± 168.2 pg/mL), and decreased after surgery (31.3 ± 43.6 pg/mL).

CONCLUSIONS

This study showed that the incidence of vasoplegia (20%) in patients with right-sided congenital heart disease undergoing cardiac surgery was double that of a population of patients undergoing aortic valve surgery (10%). Serum vasopressin concentration was not associated with vasoplegia in this population of congenital cardiac surgical patients.

The relative importance of mother and toxicosis in the selection of foods by lambs

A lamb's mother and postingestive feedback both influence learning about foods, but their relative importance is unknown. We conducted a study to compare the ingestion of elm (1) by lambs whose mothers avoided elm because ingestion of elm by mother was previously paired with the toxin lithium chloride (LiCl) (M), (2) by lambs who received a mild dose of LiCl after they ingested elm, and whose mothers also avoided elm (M + L), and (3) by lambs who received LiCl after they ingested elm, but whose mothers ate elm avidly (M vs. L); in treatment (4) neither mothers nor lambs were given LiCl (C). In all four treatments, mothers and lambs ate poplar. Each lamb was exposed with its mother for 5 min/day to poplar on days 1,2, 5, 7, 9, and 11 and to elm on days 3, 4, 6, 8, 10, and 12. Following exposures to elm on days 8, 10, and 12, lambs in treatments M + L and M vs. L were given a low dose of LiCl (100 mg/kg body weight orally in a capsule) when they ingested elm to produce an aversion to elm. During the first test after weaning, lambs could choose between elm and poplar. Lambs in C took more bites of elm than did lambs in M, M + L, and M vs. L (13, 2, 2, < 1;P >F=0.003), and they also took a higher percentage of bites from elm (42, 11, 6, 1;P >F < 0.001). The number of bites of poplar did not differ among treatments (M=31, M + L=26, M vs. L=42, C=27;P >F =0.458). During the second test, when lambs were offered only elm, lambs in C took significantly more bites of elm than those in the other treatments, and lambs in M took more bites of elm than lambs in M + L, but not M vs. L (C=38, M=16, M + L=3, M vs. L=6;P >F < 0.001). During the third test, when lambs again could choose between elm and poplar, lambs in C again took more bites of elm (C=14, M=3, M + L=< 1, M vs. L=< 1;P >F=0.034), and they also took a higher percentage of bites from elm (C=26, M=5, M + L=2, M vs. L=2;P >F < 0.001), than did lambs in the other three treatments. The number of bites of poplar did not differ among treatments (M=47, M + L=43, M vs. L=62, C =41;P >F=0.223). We conclude that the response by lambs to the toxin LiCl was more important than was the mother as a social model because lambs that received LiCl avoided elm whether or not the mother ate it.

Assessment of the abuse liability of ABT-288, a novel histamine H₃ receptor antagonist

RATIONALE

Histamine H3 receptor antagonists, such as ABT-288, have been shown to possess cognitive-enhancing and wakefulness-promoting effects. On the surface, this might suggest that H3 antagonists possess psychomotor stimulant-like effects and, as such, may have the potential for abuse.

OBJECTIVES

The aim of the present study was to further characterize whether ABT-288 possesses stimulant-like properties and whether its pharmacology gives rise to abuse liability.

METHODS

The locomotor-stimulant effects of ABT-288 were measured in mice and rats, and potential development of sensitization was addressed. Drug discrimination was used to assess amphetamine-like stimulus properties, and drug self-administration was used to evaluate reinforcing effects of ABT-288. The potential development of physical dependence was also studied.

RESULTS

ABT-288 lacked locomotor-stimulant effects in both rats and mice. Repeated administration of ABT-288 did not result in cross-sensitization to the stimulant effects of d-amphetamine in mice, suggesting that there is little overlap in circuitries upon which the two drugs interact for motor activity. ABT-288 did not produce amphetamine-like discriminative stimulus effects in drug discrimination studies nor was it self-administered by rats trained to self-administer cocaine. There were no signs of physical dependence upon termination of repeated administration of ABT-288 for 30 days.

CONCLUSIONS

The sum of these preclinical data, the first of their kind applied to H3 antagonists, indicates that ABT-288 is unlikely to possess a high potential for abuse in the human population and suggests that H3 antagonists, as a class, are similar in this regard.

Simulation-based postcardiotomy extracorporeal membrane oxygenation crisis training for thoracic surgery residents

BACKGROUND

We developed and tested a clinical simulation program in the principles and conduct of postcardiotomy extracorporeal membrane oxygenation (ECMO) with the aim of improving confidence, proficiency, and crisis management.

METHODS

Twenty-three thoracic surgery residents from unique residency programs participated in an ECMO course involving didactic lectures and hands-on simulation. A current postcardiotomy ECMO circuit was used in a simulation center to give residents training with basic operations and crisis management. Pretraining and posttraining assessments concerning confidence and knowledge were administered. Before and after the training, residents were asked to identify components of the ECMO circuit and manage crisis scenarios, including venous line collapse, arterial hypertension, and arterial desaturation.

RESULTS

In the hands-on portion, residents had difficulty identifying the gas source and flow rate, centrifugal pump head inlet, and oxygenator outflow line. Timely and accurate ECMO component identification improved significantly after training. The arterial desaturation crisis scenario gave the residents difficulty, with only 22% providing the appropriate treatment recommendations in a timely and accurate fashion. At the end of the simulation training, most residents were able to manage the crises correctly in a timely manner. Posttraining confidence-related scores increased significantly. Most of the residents strongly recommended the course to their peers and reported simulation-based training was helpful in their postcardiotomy ECMO education.

CONCLUSIONS

We developed a simulation-based postcardiotomy ECMO training program that resulted in improved ECMO confidence in thoracic surgery residents. Crisis management in a simulated environment enabled residents to acquire technical and behavioral skills that are important in managing critical ECMO-related problems.

Use of paravertebral blockade to facilitate early extubation after minimally invasive cardiac surgery

We retrospectively reviewed the first 14 patients who received preoperative paravertebral blockade prior to minimally invasive cardiac surgical procedures. The use of paravertebral blockade along with an anesthetic technique designed to facilitate rapid recovery allowed early extubation in the operating room or intensive care unit in all but one patient. Extubated patients leaving the operating room were comfortable. No postoperative respiratory complications occurred.

The proconvulsant effects of leptin on glutamate receptor-mediated seizures in mice

The metabolic-related hormone, leptin has been suggested for clinical use as an anticonvulsant based upon data generated from in vitro and in vivo non-human studies. However, a number of other non-human experiments have demonstrated proconvulsant activity for leptin. The current study investigated potential pro- and anticonvulsant effects of leptin during exposure to either glutamate (the major endogenous excitatory neurotransmitter) or three subtype-selective glutamate receptor agonists (N-methyl-d-aspartic acid [NMDA], alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA], and kainate). Male C57BL/6JRj mice were pretreated with leptin (0.1-10mg/kg, i.p.) and then administered doses of the glutamate receptor agonists (i.p.) that had been previously shown to result in clonic convulsions in approximately half of the animals tested. Leptin had no clear convulsant-related effects with either glutamate or AMPA, but it exhibited dose-related, proconvulsant activity (decreased latency to first occurrence of various convulsion-related signs, and increased percentage of animals exhibiting such signs) with both NMDA and kainate. The proconvulsant effects of leptin observed during the current study suggest that a cautious approach should be taken when administering leptin to individuals who may be prone to seizures.

The successful application of simulation-based training in thoracic surgery residency

OBJECTIVE

We developed and tested a clinical simulation program in the principles and conduct of cardiopulmonary bypass with the aim of improving confidence and proficiency in this critical aspect of cardiac surgical care.

METHODS

Fifteen residents from 6 resident-training programs who reported no prior cardiopulmonary bypass observation or simulation-based perfusion experience participated in a cardiopulmonary bypass course involving both didactic lectures and hands-on simulation. A computer-controlled hydraulic model of the human circulation was used in a specifically designed multidisciplinary simulation center environment to give the participants hands-on training with both basic operations and specific perfusion crisis scenarios. Pretraining and posttraining assessments concerning confidence, knowledge, and applications with regard to cardiopulmonary bypass were administered and compared.

RESULTS

Likert scale scores on confidence-related items increased significantly (P < .001), from 59% +/- 16% to 92% +/- 8%. Pretraining versus posttraining scores (72% +/- 14%) on similar cognitive items were not significantly different (P=.3636). Scores on similar open-ended application items before and after training improved from 62% +/- 25% to 85+/-10% (P < .0001). All subjects agreed that simulation-based cardiopulmonary bypass training was superior to classroom- and clinic-based education and that the scenarios enhanced their learning experience.

CONCLUSIONS

Simulation-based cardiopulmonary bypass training appears to be an effective technique to build the confidence of thoracic surgery residents regarding knowledge and applications. Scenario-based practice in a specifically designed simulated environment is a valuable adjunct to traditional educational methods and has the potential to improve the training of thoracic residents.

Dose-response effects of sotalol on cardiovascular function in conscious, freely moving cynomolgus monkeys

BACKGROUND AND PURPOSE

The non-selective beta-adrenoceptor antagonist, D,L-sotalol (sotalol) is commonly employed as a positive control during preclinical cardiovascular safety pharmacology testing, mainly because of its ability to prolong QT interval duration. However, no information appears in the literature, except in abstract form, regarding the dose-response effects of sotalol in unanesthetized monkeys. The current study was conducted to determine the dose- and plasma-response effects of orally administered sotalol on cardiovascular function in conscious non-human primates.

EXPERIMENTAL APPROACH

Male cynomolgus monkeys were implanted with telemetry devices and the effects of sotalol hydrochloride (5, 10 and 30 mg kg(-1) of body weight, p.o.) on arterial blood pressure, heart rate, body temperature and electrocardiogram waveform were continuously monitored for 6 h after dosing. Blood was sampled for the measurement of plasma concentrations of sotalol.

KEY RESULTS

Sotalol dose dependently decreased heart rate and prolonged RR, PR, QT and corrected QT intervals, while having little or no effects on the QRS complex, arterial pressure or body temperature, over the dose range tested. When the data were related to plasma concentrations of sotalol, it was clear that the cardiovascular effects occurred in a similar pattern and to a comparable degree as those reported in human studies.

CONCLUSIONS AND IMPLICATIONS

The current study helps demonstrate the validity of utilizing telemetry-instrumented non-human primates for the cardiovascular safety pharmacology assessment of drugs prior to first-in-human testing, and its findings may serve as a reference source for the dose- and plasma-response effects of orally administered sotalol in conscious monkeys.

Surgical management of traumatic thoracic spondyloptosis: Review of 2 cases

Spondyloptosis due to trauma is a very rare injury typically associated with motor vehicle accidents and typically at the lumbosacral junction. This report describes two patients with T6-7 and T12-L1 spondyloptosis secondary to trauma. The former was a 36-year-old man who was pinned under a 200 kg hay bale, suffering immediate paraplegia and undergoing successful posterior reduction and stabilization via a single stage posterior approach. Two years after his injury he has not developed any new deformity or neurological deterioration. The latter was a 22-year-old miner who was thrown against the ceiling of a coalmine and suffered a hyperflexion injury resulting in an immediate T12 paraplegia. Again successful reduction and stabilization was able to be achieved through pedicle screw instrumentation via a single-stage posterior approach. These two patients are the first reported cases of traumatic thoracic spondyloptosis. This report describes the rationale, likely mechanisms and surgical technique required for operative reduction and stabilization via a single-stage posterior approach.

C1 anatomy and dimensions relative to lateral mass screw placement

STUDY DESIGN

An anatomic surface osteometric analysis of cadaveric cervical spines.

OBJECTIVE

To assess the feasibility of placing a 3.5-mm cortical screw in the lateral mass of C1 in a large number of specimens for the purpose of gaining internal fixation for various conditions.

SUMMARY OF BACKGROUND DATA

Previous studies have addressed surface dimensions of the atlas vertebra and computerized tomography-measured dimensions of the lateral masses of the atlas. These studies used a limited number of specimens with potentially homogeneous origins.

METHODS

A total of 120 atlas (C1) vertebrae for a total of 240 lateral masses were examined and external measurements obtained to assess the feasibility of placing a 3.5-mm cortical screw in the lateral mass.

RESULTS

The minimum lateral mass dimensions found from 240 C1 lateral masses were 13.15 mm anterior-posterior, 4.22 mm medial-lateral, and 4.73 mm cephalocaudal. The height of the posterior arch at the groove for the vertebral artery (pedicle analog) was less than 4 mm in 46 of 240 (19.2%) arches.

CONCLUSIONS

It is feasible to safely and reproducibly place a 3.5-mm cortical screw in the lateral mass of C1 when the appropriate starting point and trajectory of the screw are chosen.

Magnetic resonance imaging clarity of the Bryan, Prodisc-C, Prestige LP, and PCM cervical arthroplasty devices

STUDY DESIGN

Prospective, randomized, controlled and double-blinded study on imaging of artificial discs.

OBJECTIVE

The purpose of this study is to compare postoperative imaging characteristics of the 4 currently available cervical arthroplasty devices at the level of implantation and at adjacent levels.

SUMMARY OF BACKGROUND DATA

Cervical arthroplasty is being performed increasingly frequently for degenerative disc disease and, in most cases, with frank neural compression. Unlike lumbar arthroplasty, performed mainly for axial back pain, decompression of neural elements may need to be confirmed with postoperative imaging after cervical arthroplasty.

METHODS

Preoperative and postoperative magnetic resonance imaging scans of 20 patients who had undergone cervical arthroplasty were assessed for imaging quality. Five cases each of the Bryan (Medtronic Sofamor Danek, Memphis, TN), Prodisc-C (Synthes Spine, Paoli, PA), Prestige LP (Medtronic Sofamor Danek), and PCM devices (Cervitech, Rockaway, NJ) were analyzed. Six blinded spinal surgeons scored twice sagittal and axial T2-weighted images using the Jarvik 4-point scale. Statistical analysis was performed comparing quality before surgery and after disc implantation at the operated and adjacent levels and between implant types. RESULTS.: Moderate intraobserver and interobserver reliability was noted. Preoperative images of patients in all implant groups had high-quality images at operative and adjacent levels. The Bryan and Prestige LP devices allowed satisfactory visualization of the canal, exit foramina, cord, and adjacent levels after arthroplasty. Visualization was significantly impaired in all PCM and Prodisc-C cases at the operated level in both the spinal canal and neural foramina. At the adjacent levels, image quality was statistically poorer in the PCM and Prodisc-C than those of Prestige LP or Bryan. CONCLUSIONS.: Postoperative visualization of neural structures and adjacent levels after cervical arthroplasty is variable among current available devices. Devices containing nontitanium metals (cobalt-chrome-molybdenum alloys in the PCM and Prodisc-C) prevent accurate postoperative assessment with magnetic resonance imaging at the surgical and adjacent levels. Titanium devices, with or without polyethylene (Bryan disc or Prestige LP), allow for satisfactory monitoring of the adjacent and operated levels. This information is crucial for any surgeon who wishes to assess adequacy of neural decompression and where monitoring of adjacent levels is desired.

Cardiac electrophysiologic interactions of bepridil, a new calcium antagonist, with enflurane, halothane, and isoflurane

Bepridil is an investigational calcium antagonist that also has fast sodium channel blocking and antidysrhythmic properties. In the present study, the potential interactions of bepridil with volatile anesthetics on cardiac electrophysiologic parameters were evaluated in open-chest dogs. Twenty-four dogs anesthetized with enflurane (n=6), halothane (n=6), isoflurane (n=6), or chloralose (n=6) received 2.5 mg/kg of bepridil intravenously (IV). Twenty-five additional dogs anesthetized with enflurane (n=7), halothane (n=6), isoflurane (n=6), or chloralose (n=6), received bepridil, 5.0 mg/kg, IV. Dogs anesthetized with cloralose served as controls. Cardiac electrophysiologic parameters were measured after the dogs were anesthetized and were repeated 5, 15, 30, 45, and 60 minutes after bepridil infusion. Plasma bepridil concentrations were also determined at the above time points. Synergy between bepridil and enflurane was demonstrated in the following cardiac electrophysiologic parameters: depression of sinus node function as evidenced by severe depression of sinus node automaticity and conduction; depression of atrioventricular function as evidenced by prolongation of the atrial-His bundle interval and the Wenckebach R-R interval; and, prolongation of the atrial effective refractory period. No synergy was demonstrated between bepridil and halothane or isoflurane when compared to bepridil's effects during chloralose anesthesia. It is concluded that significant synergistic cardiac electrophysiologic effects exist between bepridil and enflurane in dogs. It is recommended that caution be used when anesthetizing patients receiving bepridil with enflurane until human data on the use of this combination of pharmacologic agents is available.

(L)-Phenylglycine, but not necessarily other alpha2delta subunit voltage-gated calcium channel ligands, attenuates neuropathic pain in rats

Gabapentin and pregabalin have been demonstrated, both in animal pain models and clinically, to be effective analgesics particularly for the treatment of neuropathic pain. The precise mechanism of action for these two drugs is unknown, but they are generally believed to function via initially binding to the alpha2delta subunit of voltage-gated Ca2+ channels. In this study, we used a pharmacological approach to test the hypothesis whether high affinity interactions with the alpha2delta subunit alone could lead to attenuation of neuropathic pain in rats. The anti-allodynic effects of gabapentin and pregabalin, along with three other compounds--(L)-phenylglycine, m-chlorophenylglycine and 3-exo-aminobicyclo[2.2.1]heptane-2-exo-carboxylic acid (ABHCA)--discovered to be potent alpha2delta ligands, were tested in the rat spinal nerve ligation model of neuropathic pain. Gabapentin (Ki = 120 nM), pregabalin (180 nM) and (L)-phenylglycine (180 nM) were shown to be anti-allodynic, with respective ED50 values of 230, 90 and 80 micromol/kg (p.o.). (L)-Phenylglycine was as potent as pregabalin and equi-efficacious in reversing mechanical allodynia. In contrast, two ligands with comparable or superior alpha2delta binding affinities, m-chlorophenylglycine (Ki = 54 nM) and ABHCA (150 nM), exhibited no anti-allodynic effects at doses of 30-300 micromol/kg (p.o.), although these compounds achieved substantial brain levels. The data demonstrate that, at least in the rat spinal nerve ligation model of neuropathic pain, (L)-phenylglycine has an anti-allodynic effect, but two equally potent alpha2delta subunit ligands do not. These results suggest that additional mechanisms, besides alpha2delta interactions, may contribute to the effects of compounds like gabapentin, pregabalin and (L)-phenylglycine in neuropathic pain.

Structure–activity relationships of α-amino acid ligands for the α2δ subunit of voltage-gated calcium channels

A series of alpha-amino acids were identified as ligands which compete with gabapentin for binding to the alpha(2)delta subunit of voltage-dependent Ca(2+) channels. Potent analogs were identified. Their activity in an in vivo pain assay is described.

Assessing the role of metabotropic glutamate receptor 5 in multiple nociceptive modalities

Preclinical data, performed in a limited number of pain models, suggest that functional blockade of metabotropic glutamate (mGlu) receptors may be beneficial for pain management. In the present study, effects of 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a potent, selective mGlu5 receptor antagonist, were examined in a wide variety of rodent nociceptive and hypersensitivity models in order to fully characterize the potential analgesic profile of mGlu5 receptor blockade. Effects of 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP), as potent and selective as MPEP at mGlu5/mGlu1 receptors but more selective than MPEP at N-methyl-aspartate (NMDA) receptors, were also evaluated in selected nociceptive and side effect models. MPEP (3-30 mg/kg, i.p.) produced a dose-dependent reversal of thermal and mechanical hyperalgesia following complete Freund's adjuvant (CFA)-induced inflammatory hypersensitivity. Additionally, MPEP (3-30 mg/kg, i.p.) decreased thermal hyperalgesia observed in carrageenan-induced inflammatory hypersensitivity without affecting paw edema, abolished acetic acid-induced writhing activity in mice, and was shown to reduce mechanical allodynia and thermal hyperalgesia observed in a model of post-operative hypersensitivity and formalin-induced spontaneous pain. Furthermore, at 30 mg/kg, i.p., MPEP significantly attenuated mechanical allodynia observed in three neuropathic pain models, i.e. spinal nerve ligation, sciatic nerve constriction and vincristine-induced neuropathic pain. MTEP (3-30 mg/kg, i.p.) also potently reduced CFA-induced thermal hyperalgesia. However, at 100 mg/kg, i.p., MPEP and MTEP produced central nerve system (CNS) side effects as measured by rotarod performance and exploratory locomotor activity. These results suggest a role for mGlu5 receptors in multiple nociceptive modalities, though CNS side effects may be a limiting factor in developing mGlu5 receptor analgesic compounds.

ABT-594 (a nicotinic acetylcholine agonist): anti-allodynia in a rat chemotherapy-induced pain model

ABT-594 ((R)-5-(2-azetidinylmethoxy)-2-chloropyridine) represents a novel class of broad-spectrum analgesics whose primary mechanism of action is activation of the neuronal nicotinic acetylcholine receptors. The present study characterized the effects of ABT-594 in a rat chemotherapy-induced neuropathic pain model, where it attenuated mechanical allodynia with an ED50 = 40 nmol/kg (i.p.). This anti-allodynic effect was not blocked by systemic (i.p.) pretreatment with naloxone but was blocked completely with mecamylamine. Pretreatment with chlorisondamine (0.2-5 micromol/kg, i.p.) only partially blocked the effects of ABT-594 at the higher doses tested. In contrast, central (i.c.v.) pretreatment with chlorisondamine completely blocked ABT-594's anti-allodynic effect. Taken together, the data demonstrate that ABT-594 has a potent anti-allodynic effect in the rat vincristine model and that, in addition to its strong central site of action, ABT-594's effects are partially mediated by peripheral nicotinic acetylcholine receptors in this animal model of chemotherapy-induced neuropathic pain.

Biomechanical comparison of C1–2 posterior fixation techniques

Object. In a nondestructive, repeated-measures in vitro flexibility experiment, the authors compared the acute stability of C1–2 after placement of C-1 lateral mass and C-2 pars interarticularis (LC1—PC2) instrumentation with that of C1–2 transarticular screw fixation.

Methods. The effect of C-1 laminectomy and C1–2 interspinous cable/graft fixation on LC1—PC2 stability was studied. Screw pullout strengths were also compared. Seven human cadaveric occiput—C3 specimens were loaded nondestructively with pure moments while measuring nonconstrained atlantoaxial motion. Specimens were tested with graft alone, LC1—PC2 alone, LC1—PC2 combined with C-1 laminectomy, and graft-augmented LC1—PC2. Interspinous cable/graft fixation significantly enhanced LC1—PC2 stability during extension. After C-1 laminectomy, the LC1—PC2 construct allowed increased motion during flexion and extension. There was no significant difference in lax zone or range of motion between LC1—PC2 fixation and transarticular screw fixation, but graft-assisted transarticular screws yielded a significantly smaller stiff zone during extension. The difference in pullout resistance between C-1 lateral mass screws and C-2 pars interarticularis screws was insignificant. The LC1—PC2 region restricted motion to within the normal range during all loading modes. Atlantal laminectomy reduced LC1—PC2 stability during flexion and extension.

Conclusions. The instrumentation-augmented LC1—PC2 construct performed biomechanically similarly to the C1–2 transarticular screw fixation. The LC1—PC2 construct resisted flexion, lateral bending, and axial rotation well. The weakness of the LC1—PC2 fixation in resisting extension can be overcome by adding an interspinous graft to the construct.

Synovial cysts of the thoracic spine

OBJECT

Thoracic synovial cysts (TSCs) are rare and are usually the subject of case reports. The authors studied the clinical manifestations, radiological aspects, and surgical treatment in a series of patients at their institution who harbored TSCs. They also review the literature to discuss the potential factors involved in the pathogenesis of this lesion.

METHODS

A database search of 16,000 patients who underwent decompressive spine surgery at the Mayo Clinic (Rochester, MN) between 1976 and 2003 disclosed nine patients (0.06%) in whom a diagnosis of TSC had been made. All patients were men. The mean age at presentation was 73 +/- 5 years and mean duration of symptoms was 5 +/- 3 months. The mean duration of follow up was 4 +/- 3 years. The patients had no history of trauma or spine surgery. All patients had spastic paraparesis; two had urinary difficulties. Detailed neurological examination revealed myelopathy and radiculopathy with a sensory level of T10-L4. Magnetic resonance imaging revealed bilateral cysts in four patients and unilateral lesions in five. Three of the cysts were at the T-10 interspace, seven at the T-11 interspace, and three at the T-12 interspace. Seven cysts were on the right and six were on the left. Computerized tomography myelography performed in five patients revealed a gas bubble in the TSC in two patients. All patients underwent laminectomy/partial facetectomy, excision of the cyst, and decompression of the thecal sac and nerve root without any complications. None of these patients underwent a fusion. Eight patients (89%) experienced moderate to excellent relief of their preoperative signs and symptoms and one patient (11%) remained stable. There was no evidence of cyst recurrence at the site of surgery or other spinal segments at follow-up examination in any patient.

CONCLUSIONS

When compared with their lumbar and cervical spine counterparts, TSCs are exceedingly rare. Their rarity may be explained by the decreased mobility of the thoracic spinal segments. The origin of TSCs is more likely degenerative rather than traumatic. Based on their experience and the follow-up duration, surgery provided durable relief from symptoms.

Discovery of 2-(4-Pyridin-2-ylpiperazin-1-ylmethyl)-1H-benzimidazole (ABT-724), a Dopaminergic Agent with a Novel Mode of Action for the Potential Treatment of Erectile Dysfunction

A new class of agents with potential utility for the treatment of erectile dysfunction has been discovered, guided by the hypothesis that selective D4 agonists are erectogenic but devoid of the side effects typically associated with dopaminergic agents. The lead agent 2-(4-pyridin-2-ylpiperazin-1-ylmethyl)-1H-benzimidazole (1, ABT-724) was discovered by optimization of a series of benzimidazole arylpiperazines. This highly selective D4 agonist was found to be very potent and efficacious in vivo, eliciting penile erections in rats at a dose of 0.03 micromol/kg, with a positive response rate of 77% erectile incidence. Even at high doses, it was devoid of side effects in animal models of central nervous system behaviors, emesis, or nausea. The structure-activity relationship of the parent benzimidazole series leading to 1 is described, with the detailed in vitro and in vivo profiles described. Distinctive structural features were discovered that are associated with D4 selective agonism in this series of analogues.

Attenuation of mechanical allodynia by clinically utilized drugs in a rat chemotherapy-induced neuropathic pain model

Chemotherapy-induced peripheral neuropathy is a common, dose-limiting side effect of cancer chemotherapeutic agents, including the vinca alkaloids such as vincristine. The resulting symptoms, which frequently include moderate to severe pain, can often be disabling. The current study utilized a vincristine-induced neuropathic pain animal model [Pain 93 (2001) 69], in which rats were surgically implanted with mini-osmotic pumps set to deliver vincristine sulfate (30 microg kg(-1)day(-1), i.v.), to examine the time course of progression of various pain modalities and to compare the dose-response effects of clinically utilized drugs on mechanical allodynia to further validate the relevance of this model to clinical pathology. Vincristine infusion resulted in significant cold allodynia after 1 week post-infusion, however mechanical and thermal nociception showed little to no effect. In contrast, marked mechanical allodynia occurred by 1 week of vincristine infusion and returned nearly to pre-infusion levels by the 4th week after infusion pump implantation. ED(50) values (micromol/kg, p.o.) were determined in the mechanical allodynia assay for lamotrigine (82), dextromethorphan (94), gabapentin (400), acetaminophen (1100) and carbamazepine (3600); however, aspirin and ibuprofen had no effects up to 300 and 1000 micromol/kg, respectively. Additionally, ED(50) values (micromol/kg, i.p.) were determined in the mechanical allodynia assay for clonidine (0.35) and morphine (0.62), but desipramine and celecoxib had no effects up to 66 and 260 micromol/kg, respectively. Findings from the current, preclinical study further validate this model as clinically relevant for chemotherapy-induced pain. The surprisingly good effects observed with acetaminophen warrant further investigation of its mechanism(s) of action in neuropathic pain.

Activation of dopamine D4 receptors by ABT-724 induces penile erection in rats

Apomorphine, a nonselective dopamine receptor agonist, facilitates penile erection and is effective in patients suffering from erectile dysfunction. The specific dopamine receptor subtype(s) responsible for its erectogenic effect is not known. Here we report that the dopamine D(4) receptor plays a role in the regulation of penile function. ABT-724 is a selective dopamine D(4) receptor agonist that activates human dopamine D(4) receptors with an EC(50) of 12.4 nM and 61% efficacy, with no effect on dopamine D(1), D(2), D(3), or D(5) receptors. ABT-724 dose-dependently facilitates penile erection when given s.c. to conscious rats, an effect that is blocked by haloperidol and clozapine but not by domperidone. A proerectile effect is observed after intracerebroventricular but not intrathecal administration, suggesting a supraspinal site of action. s.c. injections of ABT-724 increase intracavernosal pressure in awake freely moving rats. In the presence of sildenafil, a potentiation of the proerectile effect of ABT-724 is observed in conscious rats. The ability of ABT-724 to facilitate penile erection together with the favorable side-effect profile indicates that ABT-724 could be useful for the treatment of erectile dysfunction.

Central Mechanisms Regulating Penile Erection in Conscious Rats: The Dopaminergic Systems Related to the Proerectile Effect of Apomorphine

Apomorphine has been used as a pharmacological probe of dopaminergic receptors in a variety of central nervous system disorders. The utility of apomorphine as an agent for the treatment of erectile dysfunction has also been demonstrated clinically. Apomorphine is a nonselective dopaminergic receptor agonist with potent binding affinity (Ki) of 101, 32, 26, 2.6, and 10 nM for D1, D2, D3, D4, and D5, respectively. When administered either subcutaneously (s.c.) or intracerebroventricularly (i.c.v.), apomorphine fully evoked penile erections in conscious rats with maximum effect at 0.1 micromol/kg s.c. and 3 nmol/rat i.c.v., respectively. Apomorphine was less efficacious when injected intrathecally (i.t.) to L4-L6 spinal levels (50% at 30-100 nmol/rat i.t.). Penile erection facilitated by apomorphine was blocked by haloperidol and clozapine (i.p. and i.c.v.) but not by domperidone (a peripherally acting dopaminergic receptor antagonist). In this model using conscious rats, penile erection was significantly induced by quinpirole (D2-D3-D4 receptor agonist), but not by R(+)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol (SKF38393) and R(+)-6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzapine (SKF81297) (D1 receptor agonists), or a D2 receptor agonist R-5,6-dihydro-N,N-dimethyl-4H-imidazo[4,5,1-ij]quinolin-5-amine (PNU-95666E). The role of D4 receptors in penile erection was demonstrated using selective D4 receptor agonists [(4-phenylpiperazinyl)-methyl]benzamide (PD168077) and 5-fluoro-2-[[4-(2-pyridinyl)-1-piperazinyl]methyl]-1H-indole (CP226269), whether administered systemically (s.c.) or locally in the brain (i.c.v.). The ability of apomorphine to activate D3 receptors in relation to its proerectile activity remains to be elucidated by use of selective subtype agonists. These results suggest that the proerectile action of apomorphine in rats is mediated at supraspinal levels and that this effect is not mimicked by a D2 receptor agonist but associated with activation of D4 receptors.

Prospective analysis of diplopia after anterior temporal lobectomy for mesial temporal lobe sclerosis

OBJECT

In this prospective study the authors investigated the incidence and natural history of postoperative diplopia in patients undergoing anterior temporal lobectomy (ATL) and amygdalohippocampectomy for medically intractable mesial temporal lobe epilepsy.

METHODS

Forty-seven patients scheduled for ATL for medically refractory seizures were examined preoperatively, 2 to 7 days postoperatively, and 3 to 6 months postoperatively. Ophthalmological examination including pupillary measurements, stereoacuity measurements, palpebral fissure measurements, vertical fusional amplitudes, Lancaster red green testing, visual field testing, and alternate cover testing was performed. Antiepileptic drug levels were monitored. Nine (19%) of 47 patients developed diplopia postoperatively. The diplopia was caused by trochlear nerve palsy in every case. No oculomotor nerve dysfunction was documented. Trochlear nerve function recovered completely in all patients within 3 to 6 months postoperatively.

CONCLUSIONS

Postoperative diplopia following ATL occurs more often than previously thought and is primarily due to trochlear nerve dysfunction. Awareness of this transient complication is important in preoperative patient counseling.

K-ATP opener-mediated attenuation of spontaneous bladder contractions in ligature-intact, partial bladder outlet obstructed rats

Symptoms of urinary frequency and urgency secondary to benign prostatic obstruction are common in elderly men. In many patients, these symptoms correspond to the urodynamic finding of involuntary detrusor contractions during filling cystometry (i.e., detrusor instability). Spontaneous non-voiding contractions during filling can be modeled in animals by subchronic, partial urethral obstruction. However, many investigators remove the obstructive ligature a few days prior to cystometrical evaluation (which may not be an ideal representation of the clinical situation where obstruction is still present), and all perform cystometry within 3 days post-bladder catheterization surgery (i.e., while considerable wound healing is present). In the current study, we evaluated the effects, after oral dosing, of three structurally diverse ATP-sensitive potassium channel openers (KCOs) on spontaneous contractions secondary to obstruction in rats with an intact obstructive ligature at the time of testing and 2 weeks post-bladder catheterization. ZD6169, WAY-133537 and a novel dihydropyridine KCO, A-278637, all significantly decreased spontaneous bladder contractions at 30 min post-dosing (p.o.). However, only ZD6169 (10 micromol/kg) and A-278637 (3 micromol/kg) attenuated such bladder contractions at doses that did not concurrently, significantly affect mean arterial blood pressure and heart rate. These data confirm the efficacy of KCOs to inhibit unstable contractions in obstructed rats, and they further demonstrate the positive effect of a novel, bladder-selective KCO, A-278637, in an animal model with potentially less artifact than in previous such models.

In vivo evaluation of the potency and bladder-vascular selectivity of the ATP-sensitive potassium channel openers (-)-cromakalim, ZD6169 and WAY-133537 in rats

OBJECTIVE

To compare in vivo the potency and bladder-vascular selectivity of ATP-sensitive potassium channel openers (KCOs) (-)-cromakalim, WAY-133537 and ZD6169 and a muscarinic antagonist, tolterodine in rats.

MATERIALS AND METHODS

Bladder and arterial pressures were monitored simultaneously, before and after increasing intravenous doses of compounds, in each of two urethane-anaesthetized rat bladder hyperactivity models: spontaneous non-voiding myogenic contractions secondary to partial outlet obstruction and volume-induced neurogenic contractions.

RESULTS

(-)-Cromakalim, WAY-133537 and ZD6169 caused a dose-dependent suppression of spontaneous contractions in the obstructed model, with a 50% inhibition of the contraction area under the curve at doses of 0.06, 0.14 and 2.4 micro mol/kg (intravenous), respectively. Corresponding decreases in mean arterial pressure at these effective doses were 24%, 15% and 15%, respectively. The KCO potency rank order was the same and their relative potency highly comparable in the neurogenic model. There was complete inhibition of spontaneous contractions in obstructed rats at doses corresponding to approximately 50% inhibition of the neurogenic contractions. While tolterodine caused a dose-dependent inhibition of contractions in the neurogenic model, it was ineffective at inhibiting non-voiding contractions in obstructed rats.

CONCLUSIONS

All KCOs tested caused significant decreases in arterial pressure at doses effective on the bladder in the model of obstructive instability, suggesting a lack of bladder-vascular selectivity. Similar KCO potency in both assays suggests no appreciable changes in KATP channel function as a result of partial outlet obstruction.

Surgical treatment of fibrous dysplasia of the skull in children

INTRODUCTION

We evaluate the role of surgery in the treatment of fibrous dysplasia of the skull in children.

METHODS

We identified 48 consecutive cases of fibrous dysplasia of the skull that were surgically treated at a single institution over a 23-year interval. The 28 patients that initially presented during the first two decades of life were selected for further analysis. Presenting symptoms, signs, surgical treatment, surgical outcome and the state of the disease at the extended follow-up interval were recorded.

RESULTS

Fibrous dysplasia of the skull in children most often involved the frontal, sphenoid and ethmoid bones. Most patients presented with facial asymmetry or proptosis. A gross total resection was achieved in 7 patients, subtotal resection in 17 patients, and 4 patients underwent biopsy alone. Over the follow-up interval, 7 patients had symptomatic progression of subtotally resected fibrous dysplasia and 3 patients had asymptomatic progression. The extent of resection was correlated with recurrence risk.

CONCLUSIONS

In order to prevent progression of disease, an attempt at gross total resection is indicated in cases of fibrous dysplasia of the skull in childhood where the risk of neurologic morbidity is low and cosmetic results will be acceptable.

A-315456: a selective alpha(1D)-adrenoceptor antagonist with minimal dopamine D(2) and 5-HT(1A) receptor affinity

In functional assays, A-315456, N-[3-(cyclohexylidene-(1H-imidazol-4-ylmethyl))phenyl]ethanesulfonamide, behaved as an alpha(1D)-adrenoceptor subtype selective antagonist (pA(2)=8.34) in the rat aorta. It was 83-fold less potent at the alpha(1B)-adrenoceptor subtype expressed in the rat spleen, and was inactive at the alpha(1A)-adrenoceptor subtype expressed in the rat vas deferens. Radioligand binding assays also revealed high affinity (pK(i)=8.71) for the alpha(1D)-adrenoceptor subtype and weaker affinities at the alpha(1A)-adrenoceptor (pK(i)=6.23) and alpha(1B)-adrenoceptor (pK(i)=7.86). In comparison to its potent affinity at the alpha(1D)-adrenoceptor subtype, A-315456 was 3020-, 794- and 38-fold weaker at the dopamine D(2)-, 5-HT(1A)-, and alpha(2a)-adrenoceptors, respectively. These studies indicate that A-315456 is a potent and selective alpha(1D)-antagonist that may serve as a useful pharmacological ligand to probe the physiological role of the alpha(1D)-adrenoceptor subtype in normal and disease states.

Screening mammography and breast cancer treatment patterns in older women

OBJECTIVE

To examine the impact of mammography screening on treatment options received by a cohort of older breast cancer patients.

SETTING AND POPULATION

We studied 718 newly diagnosed breast cancer patients, 67 years and over, diagnosed with TNM Stage I and II disease between 1995 and 1997 at 29 hospitals in five regions.

METHODS

Data were collected from patients, surgeons, and medical records. A breast cancer diagnosis was considered to have been by screening mammography if so reported by both patient and medical records. Bivariate and logistic regression were used to identify predictors of a women having her cancer detected by screening mammography and the relationships between mode of detection, stage of disease at diagnosis, and local treatment.

RESULTS

Women with high school or greater education were 1.75 times (95%, CI 1.11-2.75) more likely to have their cancers diagnosed by screening mammography than women who had not completed high school, controlling for other factors. Screening found earlier stage disease: 96% of women with mammographically diagnosed cancer had T1 lesions, compared to 81% of women diagnosed by other means (p = 0.001). Women with mammography detected lesions were more likely to have ductal cancer, and to be referred to radiation oncologists more than women diagnosed by other means. Controlling for stage and histology, screening remained associated with a higher likelihood of receiving breast conserving surgery (BCS) with radiation (RT) (OR 1.56, 95%, CI 1.10-2.22) than other local therapies.

CONCLUSIONS

Beyond the impact on stage, ductal cancers were more likely to be diagnosed by screening. Mammographically detected lesions were associated with referrals to radiation oncologists and higher rates of BCS and RT. Research is needed to explain the residual independent effects of mammography screening on breast cancer treatment.

Design and biological activity of (S)-4-(5-([1-(3-chlorobenzyl)-2-oxopyrrolidin-3-ylamino]methyl)imidazol-1-ylmethyl)benzonitrile, a 3-aminopyrrolidinone farnesyltransferase inhibitor with excellent cell potency

The synthesis, structure-activity relationships, and biological properties of a novel series of imidazole-containing inhibitors of farnesyltransferase are described. Starting from a 3-aminopyrrolidinone core, a systematic series of modifications provided 5h, a non-thiol, non-peptide farnesyltransferase inhibitor with excellent bioavailability in dogs. Compound 5h was found to have an unusually favorable ratio of cell potency to intrinsic potency, compared with other known FTIs. It exhibited excellent potency against a range of tumor cell lines in vitro and showed full efficacy in the K-rasB transgenic mouse model.