Ubiquitin-specific protease 7 inhibitors reveal a differentiated mechanism of p53-driven anti-cancer activity

The USP7 deubiquitinase regulates proteins involved in the cell cycle, DNA repair, and epigenetics and has been implicated in cancer progression. USP7 inhibition has been pursued for the development of anti-cancer therapies. Here, we describe the discovery of potent and specific USP7 inhibitors exemplified by FX1-5303. FX1-5303 was used as a chemical probe to study the USP7-mediated regulation of p53 signaling in cells. It demonstrates mechanistic differences compared to MDM2 antagonists, a related class of anti-tumor agents that act along the same pathway. FX1-5303 synergizes with the clinically approved BCL2 inhibitor venetoclax in acute myeloid leukemia (AML) cell lines and ex vivo patient samples and leads to strong tumor growth inhibition in in vivo mouse xenograft models of multiple myeloma and AML. This work introduces new USP7 inhibitors, differentiates their mechanism of action from MDM2 inhibition, and identifies specific opportunities for their use in the treatment of AML.

Memantine for Pediatric Patients Receiving Cranial Irradiation: A Pilot Study

PURPOSE/OBJECTIVE(S)

While memantine has become standard in certain adults receiving brain RT to decrease the cognitive impacts of RT, it is unknown whether pediatric patients can take and tolerate memantine or experience benefit. In this prospective single-arm feasibility study, we hypothesized pediatric patients receiving brain RT would tolerate memantine with good treatment adherence.

MATERIALS/METHODS

Patients aged 4-18 years with a primary CNS malignancy (excluding WHO Grade IV astrocytoma and glioblastoma) receiving intracranial RT were eligible. A 6-month course of memantine was given during and after RT. Dosing began once daily at 5 mg with up-titration in 5 mg increments over 4 weeks to a weight-based maximum (0.4 mg/kg to the closest 5 mg), not to exceed 10 mg BID. To reduce patient and clinical research associate (CRA) burden, medication adherence was tracked via the Medisafe Pill and Reminder application which study staff helped install on the patient or parent's smart phone. A paper pill diary was provided for those unable to use the app. The primary endpoint was to achieve 80% adherence rate to memantine in 80% of patients measured 1-month post-RT.

RESULTS

Eighteen patients (14 male and 4 female, median age 11.5 years (range: 4-18)) were enrolled from 2020-2022. The study closed early after enrolling 18 of 20 planned patients to avoid competing with the phase III randomized Children's Oncology Group (COG) study AACL2031. One patient withdrew for cognition-altering substance-use, leaving 17 patients with data available for analysis. Histologies included germ cell tumor (n = 6), craniopharyngioma (n = 3), choroid plexus papilloma (n = 2), ependymoma (n = 2), glial/astrocytoma (n = 2), medulloblastoma (n = 1), and meningioma (n = 1). Thirteen had surgery, and 9 received chemotherapy. Eight received craniospinal irradiation (CSI). Median RT dose was 54 Gy (range 36-59.4) in 30 fractions (range: 20-33). At data freeze, all 17 had passed the 1-month post-RT time point. One patient discontinued memantine after a single dose due to nausea. Pill-reports were available for 14 of the remaining 16; two patients did not complete digital pill logs. For those with complete logs, all adherence rates were above 80%, with a median of 99.32% pill completion rate (range: 92.67-100). Seven (50%) took 100% of prescribed doses. Irrespective of adherence for the 2 unavailable for evaluation, the primary endpoint was still achieved. Grade 1 toxicities included headache (n = 6, 35%) and constipation (n = 1, 6%); there were no grade 2+ toxicities. At last follow-up, 15/16 have completed the full 6-month memantine course. Secondary endpoints including neurocognitive evaluations have not yet been met and will be the subject of future reports.

CONCLUSION

Memantine is a feasible and well-tolerated addition to multi-modality treatment for pediatric brain tumors. Secondary endpoints of this study and results of the ongoing COG study are awaited to define the value of memantine in this population.

Abstract 1338: Discovery of novel, potent USP7 inhibitors that upregulate p53 leading to anti-proliferative effects in cancer cells

Introduction: Ubiquitin-specific protease 7 (USP7) is a deubiquitinase that regulates several proteins involved in cell cycle, DNA repair, genomic stability, and epigenetics and has been implicated in cancer progression. A key substrate of USP7 is MDM2, the oncogenic E3 ubiquitin ligase that promotes degradation of the tumor suppressor p53. USP7-mediated stabilization of MDM2 leads to the degradation of p53, preventing cell cycle arrest and the induction of apoptosis and promoting tumor cell growth. In addition to the MDM2-p53 pathway, USP7 regulates a number of other substrates involved in cancer, including PIM2 kinase, MYCN, the DNA methyltransferase DNMT1, and the PTEN tumor suppressor. Consistent with its function promoting oncogenic signaling pathways, genetic and pharmacological inhibition of USP7 has been shown to inhibit growth of a number of tumor cell lines in vitro and in vivo, and this anti-tumor activity is significantly enriched among cells expressing wild type p53. Thus, inhibition of USP7 is a promising therapeutic strategy, especially in cancers carrying wild type p53 that can be reactivated by suppression of MDM2.

Results: We have discovered a new class of potent and selective USP7 inhibitors. These compounds bind to USP7 and prevent deubiquitinase activity in biochemical activity assays with picomolar potency. Our compounds induce accumulation of p53 and exhibit IC50s below 50 nM in cell viability assays in Multiple Myeloma and Acute Myeloid Leukemia (AML) cell lines. In AML cell lines, our USP7 inhibitors strongly synergize with the approved Bcl-2 inhibitor venetoclax. Unlike MDM2 antagonists currently undergoing clinical trials in AML, these USP7 inhibitors do not lead to a significant increase in MDM2 levels, and our compounds result in a more modest induction of p53, both of which could provide significant safety benefits. We have demonstrated differential sensitivity to MDM2 antagonists and our USP7 inhibitors in select cell lines and show that this effect is dependent upon p53 induction. Our compounds are orally bioavailable with a desirable PK profile in mice and induce p53 in tumor cells in CDX mouse models of Multiple Myeloma.

Conclusions: We have identified novel, potent, orally bioavailable USP7 inhibitors that lead to p53 accumulation and cytotoxicity in cancer cells. We demonstrate mechanistic differences between USP7 and MDM2-p53 antagonists, which may lead to a safety advantage. We observe strong synergy between USP7 inhibitors and an approved treatment. Our lead compounds have favorable drug-like properties, promising mouse PK profiles, and can induce p53 accumulation in mouse CDX tumor models. These data demonstrate the therapeutic potential of our USP7 inhibitors and reveal specific opportunities for their use in the treatment of Multiple Myeloma and AML.

Citation Format: Alan Futran, Tao Lu, Katherine Amberg-Johnson, Xiaoxiao Yang, Saidi He, Jeffrey Bell, Sarah Boyce, Markus Dahlgren, Karen Dingley, Liping Fang, Heidi Koldsoe, Zef Konst, Fang-Yu Lin, Robert Pelleltier, Heng Qian, Mats Svensson, Michael Trzoss, Jie Xu, Shuping Xu, Zhaowu Xu, Engin Yapici, Yan Zhang, Li Xing, Takao Suzuki, Xianhai Huang, Jiayi Xu, Hamish Wright, Kristian Jensen, Wayne Tang, Tao Guo, Karen Akinsanya, David Madge. Discovery of novel, potent USP7 inhibitors that upregulate p53 leading to anti-proliferative effects in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1338.

Clinical Evaluation of a Device for the Treatment of Cellulite: Triactive

Introduction:

Cellulite has always been a difficult condition for patients and cosmetic physicians to treat. Even if improvement is made in the appearance of cellulite, no machine or topical treatment exists that can provide long-term results in the treatment of cellulite. We evaluated a technique that increases lymphatic drainage and vascular permeation to assist in decreasing the appearance of cellulite.

Materials and Methods:

Sixteen female patients underwent 12 treatments with a device called Triactive, which has a triple-pronged mechanism of action consisting of low-level suction, diode laser, and contact cooling. We measured results by waist, hip, and thigh circumference as well as elasticity, thermography, and blinded photograph evaluations.

Results:

We found a small decrease in hip and thigh circumference as well as an increase in elasticity of the treated cellulite. Evaluation of the photographs yielded an overall 21% average improvement in the appearance of cellulite. There was no change in thermography data after treatments. Results were not present at 1 month.

Discussion:

The Triactive offers a method to temporarily decrease the appearance of cellulite. It appears that treatments must be continued to maintain results. Further study and larger patient groups are needed before this treatment can be recommended above other available treatments.

Pre-linguistic children with cleft palate: growth of gesture, vocalization, and word use

Children with cleft lip and/or palate show early delays in speech and vocabulary development that may have an impact on later communication and social development. While delays in the complexity of babbling may put children at risk for later delays in speech and language development, there is considerable variability in development. This study focused on the rate of children's communication acts, canonical vocalizations, and word use as they made the transition from the pre-linguistic to linguistic development. The study included 15 children with non-syndromic cleft lip and/or palate who were seen at three time points between 17-34 months age. Communication rates were calculated from parent-child language samples collected during play activities. Assignment to linguistic stages was based on the children's expressive vocabulary, as reported on the MacArthur Communicative Development Inventory: Words and Sentences. From the pre-linguistic to linguistic level, the children's average rate per minute of: communicative acts overall increased significantly from 1.49 to 3.07 per minute; canonical vocalizations from 0.21 to 0.90 per minute; and word use from 0.16 to 3.61 per minute. Rates of communicative acts were associated with later word use. It appears that children with clefts rely on non-verbal communicative acts when verbal development is delayed.

Design and Development of a New Multi-Projection X-Ray System for Chest Imaging

Overlapping anatomical structures may confound the detection of abnormal pathology, including lung nodules, in conventional single-projection chest radiography. To minimize this fundamental limiting factor, a dedicated digital multi-projection system for chest imaging was recently developed at the Radiology Department of Duke University. We are reporting the design of the multi-projection imaging system and its initial performance in an ongoing clinical trial. The system is capable of acquiring multiple full-field projections of the same patient along both the horizontal and vertical axes at variable speeds and acquisition frame rates. These images acquired in rapid succession from slightly different angles about the posterior-anterior (PA) orientation can be correlated to minimize the influence of overlying anatomy. The developed system has been tested for repeatability and motion blur artifacts to investigate its robustness for clinical trials. Excellent geometrical consistency was found in the tube motion, with positional errors for clinical settings within 1%. The effect of tube-motion on the image quality measured in terms of impact on the Modulation Transfer Function (MTF) was found to be minimal. The system was deemed clinic-ready and a clinical trial was subsequently launched. The flexibility of image acquisition built into the system provides a unique opportunity to easily modify it for different clinical applications, including tomosynthesis, correlation imaging (CI), and stereoscopic imaging.

Epidermal lipid metabolism of cultured skin substitutes during healing of full-thickness wounds in athymic mice

Cultured epidermal keratinocytes provide an abundant supply of biologic material for wound treatment. Because restoration of barrier function is a definitive criterion for efficacy of wound closure and depends on the lipids present in the epidermis, we analyzed lipid composition of the epidermis in cultured skin substitutes in vitro and after grafting to athymic mice. The cultured skin substitutes were prepared from human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan substrates. After 14 days of incubation, cultured skin substitutes were grafted orthotopically onto full-thickness wounds in athymic mice. Samples for lipid analysis were collected after 14 and 34 days of in vitro incubation, and 3 weeks and 4 months after grafting. Both in vitro samples show disproportions in epidermal lipid profile as compared with the native human epidermis, i.e., a low amount of phospholipids (indicating imbalance in proliferation and differentiation); a large excess of triglycerides (storage lipids); and low levels of free fatty acids, gluco-sphingolipids, cholesterol sulfate, and ceramides-suggesting abnormal composition of stratum corneum barrier lipids. Fatty acid analysis of cultured skin substitutes in vitro revealed insufficient uptake of linoleic acid, which resulted in increased synthesis of and substitution with monounsaturated fatty acids, mainly oleic acid. These abnormalities were partially corrected by 3 weeks after grafting; and 4 months after grafting, all epidermal lipids, with some minor exceptions, were synthesized in proportions very similar to human epidermis. Results of this study show that grafting of cultured skin substitutes to a physiologic host permits the recovery of lipid in proportion to that required for barrier formation in normal human epidermis.

Risk of cancer treatment-related osteoporosis and fractures among women with breast cancer receiving aromatase inhibitors

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Background: Aromatase inhibitors (AIs) are a novel hormonal therapy for breast cancer. However, AIs can cause bone loss by blocking estrogen production. This study aims to assess the association between AIs and treatment-related bone loss in a large managed care population of women with breast cancer. Methods: Using medical and pharmacy claims data from over 5 million beneficiaries between 01/01/1998 and 01/31/2005, we identified 12,368 patients with ≥ 2 breast cancer claims in a 6-month period, who also had no bone metastasis and no prior osteoporosis or fracture claims. Patients who received anti-estrogen therapy were also excluded to remove the protective confounding effects. 1,354 patients receiving an AI (anastrozole, exemestane, letrozole) were compared to 11,014 controls who did not receive an AI with respect to their risk of bone loss. The observation start date for the AI and control groups was defined as the service date of the first AI claim and breast cancer claim, respectively. The bone loss endpoints analyzed were osteoporosis (including osteopenia) and clinical fractures. Results: The univariate analysis found that the prevalence of osteoporosis was 8.7% in the AI group vs. 7.1% in the control group, resulting in a statistically significant relative risk of 1.3 (95% CI=1.1–1.6, p=0.01). The prevalence of bone fracture was also statistically significantly elevated in the AI group compared to the controls (13.5% vs. 10.3%) with a relative risk of 1.4 (95% CI=1.2–1.6, p=0.001). Multivariate Cox proportional hazards regressions showed that after adjusting for age and comorbidities, the risk of bone loss remained statistically significantly higher in the AI group than the non-AI group, with 27% (95% CI=4%-55%, p=0.02) and 21% (95% CI=3%-43%, p=0.02) increase in the risk of osteoporosis and fractures, respectively. Conclusions: This retrospective longitudinal analysis of a large cohort of breast cancer patients corroborates previous findings from smaller clinical trials and demonstrates that AI therapies carry an increased risk of bone loss. Monitoring and treatment management strategies to alleviate bone loss risk are warranted in women receiving AI for breast cancer.

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Randomized, controlled surgical trial of preoperative tumor curettage of basal cell carcinoma in Mohs micrographic surgery

BACKGROUND

The use of preoperative tumor curettage in Mohs micrographic surgery has never been prospectively systematically assessed.

OBJECTIVE

To assess the utility of preoperative tumor curettage in Mohs micrographic surgery for primary or recurrent, well-defined basal cell carcinoma less than 2 cm in diameter located on the head or neck.

METHODS

Patients were randomized to either preoperative tumor curettage or control group and were compared in terms of percent surface area increase from tumor surface area to wound surface area, absolute surface area increase, number of tissue layers removed, types of repairs performed, and postoperative complications. Multivariate analysis was performed to see if tumor location, appearance (exophytic or flat), or histology affected any of the above.

RESULTS

The preoperative tumor curettage group had a 399% (95% confidence interval [CI] 346-452) mean surface area increase from tumor to wound surface area versus 263% (95% CI 216-311) for control group (P=.0002). The preoperative tumor curettage group had a mean absolute surface area increase of 1.78 cm2 (95% CI 1.57-1.99) versus 1.40 cm2 (95% CI 1.15-1.65) for control group (P=.02). The preoperative tumor curettage group had fewer tissue layers removed (P=.3). Preoperative tumor curettage had no effect on types of repairs performed or number or type of postoperative complications. Tumor appearance and histology had no effect on any of the above end points.

CONCLUSION

Preoperative tumor curettage was associated with significantly greater percent surface area increase and absolute surface area increase from tumor surface area to wound surface area. This difference did not affect type of repair performed or postoperative complications.

P-Glycoprotein efflux reduces the brain concentration of the substance P (NK1 receptor) antagonists SR140333 and GR205171: a comparative study using mdr1a-/- and mdr1a+/+ mice

Investigation of the antidepressant-like actions of substance P (NK1 receptor) antagonists has been hindered by the few available compounds that bind with high affinity to the rat and mouse NK1 receptor, as these are the most commonly used preclinical species. The best available compounds for such studies are SR140333 and GR205171. However, SR140333 does not penetrate the central nervous system (CNS) after systemic administration, and GR205171 is active only at high doses, where unspecific pharmacological effects occur, so that changes in behaviour cannot be attributed to selective NK1 receptor blockade. These compounds may be substrates for P-glycoprotein (P-gp) and hence are actively excluded from the brain. The present studies used mdr1a-/- mice, a spontaneously occurring mutant that is deficient in P-gp, to examine the CNS penetration of SR140333 and GR205171. Following systemic administration of SR140333 and GR205171 (0.01-10 mg/kg i.v.), considerably higher drug concentrations were achieved in the brains of mdr1a-/- than in mdr1a+/+ mice, and this corresponded with a greater ability to inhibit NK1-agonist-induced behaviours in the mdr1a-/- mutants. Moreover, an NK1-receptor-specific inhibition of aggressive behaviour by GR205171 (10 mg/kg) could be demonstrated in mdr1a-/-, but not mdr1a+/+, mice. These findings suggest that P-gp deficient mice may have useful applications in behavioural pharmacology studies, especially when highly brain-penetrant compounds are not yet available.

Neurological phenotype and synaptic function in mice lacking the CaV1.3 alpha subunit of neuronal L-type voltage-dependent Ca2+ channels

Neuronal L-type calcium channels have been implicated in pain perception and neuronal synaptic plasticity. To investigate this we have examined the effect of disrupting the gene encoding the CaV1.3 (alpha 1D) alpha subunit of L-type Ca2+ channels on neurological function, acute nociceptive behavior, and hippocampal synaptic function in mice. CaV1.3 alpha 1 subunit knockout (CaV1.3 alpha 1(-/-)) mice had relatively normal neurological function with the exception of reduced auditory evoked behavioral responses and lower body weight. Baseline thermal and mechanical thresholds were unaltered in these animals. CaV1.3 alpha 1(-/-) mice were also examined for differences in N-methyl-D-aspartate (NMDA) receptor-dependent (100 Hz tetanization for 1 s) and NMDA receptor-independent (200 Hz in 100 microM DL-2-amino-5-phosphopentanoic acid) long-term potentiation within the CA1 region of the hippocampus. Both NMDA receptor-dependent and NMDA receptor-independent forms of long-term potentiation were expressed normally. Radioligand binding studies revealed that the density of (+)[3H]isradipine binding sites in brain homogenates was reduced by 20-25% in CaV1.3 alpha 1(-/-) mice, without any detectable change in CaV1.2 (alpha 1C) protein levels as detected using Western blot analysis. Taken together these data indicate that following loss of CaV1.3 alpha 1 subunit expression there is sufficient residual activity of other Ca2+ channel subtypes to support NMDA receptor-independent long-term potentiation and some forms of sensory behavior/function.

The substance P (NK1) receptor antagonist L-760735 inhibits fear conditioning in gerbils

The ability of the substance P (NK(1) receptor) antagonist (SPA) L-760735 to inhibit conditioned fear was assessed in gerbils using a four plate apparatus. Animals that had been treated with diazepam (3 mg/kg) or L-760735 (3 mg/kg) 30 min before a 3 min conditioning session in the apparatus exhibited a release of plate crossings during the retest session approximately 3 h later. Plate crossings were also increased when animals received diazepam or L-760735 30 min before the retest session. In contrast, fluoxetine and venlafaxine (30 mg/kg) did not exhibit anxiolytic-like effects. During the retest session, gerbils drummed their hind feet on the floor; this behaviour was not observed spontaneously in gerbils that were naïve to the apparatus. Foot drumming was abolished by pretreatment with L-760735 or diazepam (3 mg/kg) but was markedly increased following administration of fluoxetine or venlafaxine (30 mg/kg). Foot drumming elicited by aversive conditioning alone or in combination with fluoxetine was abolished by administration of L-760735 and by amygdala lesions involving the basolateral and lateral nuclei, indicating that this behaviour is an alarm signal or fear response mediated via release of substance P in brain circuits involving the amygdala. The observations provide further evidence for an anxiolytic-like profile of SPAs in preclinical assays and demonstrate a clear difference between the actions of SPAs and established antidepressant drugs.

Treatment of atopic dermatitis and psoriasis vulgaris with bupropion-SR: a pilot study

OBJECTIVE

To determine whether the antidepressant bupropion may be useful in treating atopic dermatitis and psoriasis in nondepressed patients.

METHOD

Ten nondepressed subjects with atopic dermatitis and 10 with psoriasis completed a single-track, open-label treatment protocol with bupropion-SR in doses of 150 mg/day and 300 mg/day, administered sequentially for 3 weeks each, followed by a 3-week wash-out. Treatment response was assessed at the end of each 3-week period.

RESULTS

Six of the 10 subjects with atopic dermatitis showed a reduction in affected body surface area by the end of 6 weeks of bupropion treatment, with affected area increasing toward the prestudy baseline in all responders following bupropion discontinuation-a highly significant treatment effect (p =.0003). Of the 10 subjects having psoriasis, improvement over baseline after 6 weeks of treatment was seen in eight subjects, with coverage increasing toward the prestudy baseline in the responders following bupropion discontinuation (p =.001). Average reduction in affected area in the responders at week 6 of treatment was approximately 50% in both groups.

CONCLUSIONS

The generally good tolerability and relative safety of bupropion-SR makes a trial of this agent worthwhile in patients with atopic dermatitis or psoriasis who have failed treatment with more conventional medications. Normalization by bupropion of potentially causative neuroendocrine, immunologic, or catecholaminergic abnormalities in both of these dermatologic disorders is a possible mechanism of action for the observed salutary effects of this drug on our subjects' skin disease.

Paraneoplastic dermatoses

Skin manifestations of systemic disease and malignancy are protean. The recognition of a potentially paraneoplastic dermatosis as such must prompt an investigation for occult malignancy. Lack of familiarity with cutaneous clues of internal malignancy may delay diagnosis and treatment of cancer. It is important to consider a paraneoplastic process in the differential diagnosis of a number of eruptive and treatment-resistant dermatoses. These dermatoses may be the first sign of an occult neoplasm. Their recognition may assist in cancer detection and the swift induction of appropriate therapy.

CO2 laser treatment of epidermal nevi: long-term success

BACKGROUND

Epidermal nevi have been notoriously difficult to treat due to their large size and often conspicuous location. Variable results have been obtained with different laser treatments, and scarring and/or incomplete removal is typical after excisional or other destructive modalities.

OBJECTIVE

To outline the successful use of a short-pulsed CO2 laser in the long-term eradication of epidermal nevi in three patients.

METHODS

Three females (ages 15-19) presented with extensive grouped verrucous papules and plaques on the face, trunk, and extremities. A pulsed CO2 laser was used to vaporize the lesions using a 500 mJ pulse energy, 3 mm spotsize, and 7 watts of power.

RESULTS

All lesions healed without incident. No lesional recurrence was observed 10 to 13 months after treatment except in one small area on the ankle in one patient.

CONCLUSIONS

Carbon dioxide laser vaporization of epidermal nevi provides good clinical effect and offers unique advantages for the treatment of these lesions, including effective intraoperative hemostasis with excellent lesional visualization. It is also possible to treat widespread areas in one laser treatment session. While the results of this series clearly show the benefit of CO2 laser treatment, epidermal nevi may not always respond so favorably, due in part to the variability in their depths of involvement.

Increased mortality after coronary artery bypass graft surgery is associated with increased levels of postoperative creatine kinase-myocardial band isoenzyme release: results from the GUARDIAN trial

OBJECTIVES

We sought to determine if elevated cardiac serum biomarkers after coronary artery bypass graft surgery (CABG) are associated with increased medium-term mortality and to identify patients that may benefit from better postoperative myocardial protection.

BACKGROUND

The relationship between the magnitude of cardiac serum protein elevation and subsequent mortality after CABG is not well defined, partly because of the lack of large, prospectively studied patient cohorts in whom postoperative elevations of cardiac serum markers have been correlated to medium- and long-term mortality.

METHODS

The GUARD during Ischemia Against Necrosis (GUARDIAN) study enrolled 2,918 patients assigned to the entry category of CABG and considered as high risk for myocardial necrosis. Creatine kinase-myocardial band (CK-MB) isoenzyme measurements were obtained at baseline and at 8, 12, 16 and 24 h after CABG.

RESULTS

The unadjusted six-month mortality rates were 3.4%, 5.8%, 7.8% and 20.2% for patients with a postoperative peak CK-MB ratio (peak CK-MB value/upper limits of normal [ULN] for laboratory test) of < 5, > or = 5 to <10, > or =10 to < 20 and > or =20 ULN, respectively (p < 0.0001). The relationship remained statistically significant after adjustment for ejection fraction, congestive heart failure, cerebrovascular disease, peripheral vascular disease, cardiac arrhythmias and the method of cardioplegia delivery. Receiver operating characteristic curve analysis revealed an area under the curve of 0.648 (p < 0.001); the optimal cut-point to predict six-month mortality ranged from 5 to 10 ULN.

CONCLUSIONS

Progressive elevation of the CK-MB ratio in clinically high-risk patients is associated with significant elevations of medium-term mortality after CABG. Strategies to afford myocardial protection both during CABG and in the postoperative phase may serve to improve the clinical outcome.

Intra-amygdala injection of the substance P [NK(1) receptor] antagonist L-760735 inhibits neonatal vocalisations in guinea-pigs

The involvement of the basolateral amygdala in mediating the inhibition of neonatal vocalisation by substance P (NK(1) receptor) antagonists was examined. These studies determined whether the time course for separation-induced vocalisations in guinea-pig pups coincided with NK(1) receptor internalisation (a marker of substance P release) in the amygdala, and whether vocalisations could be blocked by focal injection of the NK(1) receptor antagonist L-760735 into this brain region. The peak period for neonatal vocalisations occurred 5-10 min following maternal separation. This coincided with the peak increase in the number of cells in the basolateral amygdala exhibiting NK(1) receptor endocytosis, consistent with the proposal that substance P is released in the amygdala as a result of isolation stress. Focal injection of L-760735 (15 nmol per side) but not L-770765 (an analogue of L-760735 which has low NK(1) receptor affinity) into the basolateral amygdala attenuated separation-induced vocalisations. In contrast, injection of L-760735 (15 nmol per side) into the dorsal ventricular nucleus of the thalamus, a region with relatively low density of NK(1) receptors, had no effect on neonatal vocalisations. These findings are consistent with other evidence that the amygdala is one possible site of action for the inhibition of neonatal vocalisations by substance P antagonists.

Clinical guidelines for the use of the prone position in acute respiratory distress syndrome

The mortality associated with acute respiratory distress syndrome (ARDS) remains high. It has been suggested that use of the prone position may improve survival. However, approaches to the use of the position are often haphazard. The development of clinical guidelines indicating the need for the prone position in ARDS and the process by which the manoeuvre may be performed were thought to be important for two reasons. Primarily, we sought to improve oxygenation through the use of the prone position whilst promoting patient safety. Secondly, we wished to standardize our approach to the use of the prone position and make recommendations for practice so that its use was no longer seen as a last resort in the management of ARDS. The process associated with the development of clinical guidelines is first described. This is followed by presentation of the clinical guidelines. Included in these are the criteria and discussion which indicate consideration of the prone position, potential exclusion criteria, pre-turn considerations, the turning technique, monitoring the effectiveness of the prone position, passive movements and limb positioning and, finally, documentation of the problems associated with use of the prone position. The paper concludes with discussion concerning the potential for future research in this area.

Etoricoxib (MK-0663): preclinical profile and comparison with other agents that selectively inhibit cyclooxygenase-2

We report here the preclinical profile of etoricoxib (MK-0663) [5-chloro-2-(6-methylpyridin-3-yl)-3-(4-methylsulfonylphenyl) pyridine], a novel orally active agent that selectively inhibits cyclooxygenase-2 (COX-2), that has been developed for high selectivity in vitro using whole blood assays and sensitive COX-1 enzyme assays at low substrate concentration. Etoricoxib selectively inhibited COX-2 in human whole blood assays in vitro, with an IC(50) value of 1.1 +/- 0.1 microM for COX-2 (LPS-induced prostaglandin E2 synthesis), compared with an IC(50) value of 116 +/- 8 microM for COX-1 (serum thromboxane B2 generation after clotting of the blood). Using the ratio of IC(50) values (COX-1/COX-2), the selectivity ratio for the inhibition of COX-2 by etoricoxib in the human whole blood assay was 106, compared with values of 35, 30, 7.6, 7.3, 2.4, and 2.0 for rofecoxib, valdecoxib, celecoxib, nimesulide, etodolac, and meloxicam, respectively. Etoricoxib did not inhibit platelet or human recombinant COX-1 under most assay conditions (IC(50) > 100 microM). In a highly sensitive assay for COX-1 with U937 microsomes where the arachidonic acid concentration was lowered to 0.1 microM, IC(50) values of 12, 2, 0.25, and 0.05 microM were obtained for etoricoxib, rofecoxib, valdecoxib, and celecoxib, respectively. These differences in potency were in agreement with the dissociation constants (K(i)) for binding to COX-1 as estimated from an assay based on the ability of the compounds to delay the time-dependent inhibition by indomethacin. Etoricoxib was a potent inhibitor in models of carrageenan-induced paw edema (ID(50) = 0.64 mg/kg), carrageenan-induced paw hyperalgesia (ID(50) = 0.34 mg/kg), LPS-induced pyresis (ID(50) = 0.88 mg/kg), and adjuvant-induced arthritis (ID(50) = 0.6 mg/kg/day) in rats, without effects on gastrointestinal permeability up to a dose of 200 mg/kg/day for 10 days. In squirrel monkeys, etoricoxib reversed LPS-induced pyresis by 81% within 2 h of administration at a dose of 3 mg/kg and showed no effect in a fecal 51Cr excretion model of gastropathy at 100 mg/kg/day for 5 days, in contrast to lower doses of diclofenac or naproxen. In summary, etoricoxib represents a novel agent that selectively inhibits COX-2 with 106-fold selectivity in human whole blood assays in vitro and with the lowest potency of inhibition of COX-1 compared with other reported selective agents.

Warm-coding deficits and aberrant inflammatory pain in mice lacking P2X3 receptors

ATP activates damage-sensing neurons (nociceptors) and can evoke a sensation of pain. The ATP receptor P2X3 is selectively expressed by nociceptors and is one of seven ATP-gated, cation-selective ion channels. Here we demonstrate that ablation of the P2X3 gene results in the loss of rapidly desensitizing ATP-gated cation currents in dorsal root ganglion neurons, and that the responses of nodose ganglion neurons to ATP show altered kinetics and pharmacology resulting from the loss of expression of P2X(2/3) heteromultimers. Null mutants have normal sensorimotor function. Behavioural responses to noxious mechanical and thermal stimuli are also normal, although formalin-induced pain behaviour is reduced. In contrast, deletion of the P2X3 receptor causes enhanced thermal hyperalgesia in chronic inflammation. Notably, although dorsal-horn neuronal responses to mechanical and noxious heat application are normal, P2X3-null mice are unable to code the intensity of non-noxious 'warming' stimuli.

Analgesic and toxic effects of ABT-594 resemble epibatidine and nicotine in rats

The present study directly compared the antinociceptive and toxic effects of the neuronal nicotinic receptor agonist ABT-594 ((R)-5-(2-azetidinylmethoxy)-2-chloropyridine) with (-)-nicotine and (+)-epibatidine. Like (-)-nicotine (0.8 and 1.6 mg/kg s.c.) and (+)-epibatidine (0.005 and 0.01 mg/kg s.c.), ABT-594 (0.05 and 0.1 mg/kg s.c.) increased response latencies in the hot-plate test in rats, indicating that it has antinociceptive activity. In contrast to (-)-nicotine and (+)-epibatidine, ABT-594 did not cause rotarod impairment at antinociceptive doses but did cause hypothermia and life-threatening adverse effects including seizures. ABT-594 (0.01 and 0.1 mg/kg i.v.) also produced a dose-dependent increase in blood pressure resembling that observed with (-)-nicotine (0.03, 0.1 and 0. 03 mg/kg i.v.) and (+)-epibatidine (0.001 and 0.003 mg/kg i.v.). Both the antinociceptive and toxic effects (convulsions and hypertension) were abolished by pretreatment with the brain penetrant neuronal nAChR antagonist mecamylamine (1 mg/kg s.c.; i.v. for cardiovascular studies), demonstrating that these actions of ABT-594 were mediated via activation of neuronal nicotinic receptors. Continuous infusion of ABT-594 (0.2 mg/kg per day s.c.) to rats for 7 days followed by challenge with mecamylamine (1 mg/kg i.p.) induced a nicotine-like abstinence syndrome suggesting that ABT-594 has nicotine-like dependence liability. These findings indicate that the acute safety profile of ABT-594 is not significantly improved over other nicotinic analgesics.

Outcome of pregnancies complicated by pre-gestational diabetes mellitus

Pregestational diabetes mellitus (DM) is associated with adverse fetal and maternal outcomes. Studies suggest that optimal control of diabetes before and during pregnancy minimises these risks. There are few recent reviews of outcomes of pregnancies complicated by DM in Australia. Ninety-three pregnancies in women with DM at our hospital since 1989 were identified. We collected data for maternal age, type of diabetes, duration of therapy, complications of diabetes, maternal complications of pregnancy and fetal outcomes including malformations. The rate of pregnancy planning with optimal glycaemic control at conception was low in our population, particularly in patients with Type 1 diabetes. Women who smoked had worse glycaemic control, and a higher rate of miscarriage. There was a high rate of Caesarean section, particularly in those women with Type 1 diabetes (77.4%). The rate of Caesarean section was lower in planned pregnancies. There were no perinatal deaths. The number of neonates with major congenital anomalies was high (13%) in the Type 1 population. It is important to increase the rates of prepregnancy planning and to optimise glycaemic control before pregnancy. In many cases there has been a long interval between diagnosis and pregnancy, so all women with diabetes should receive counselling at frequent intervals about pregnancy and the importance of planning. Women who planned their pregnancies had improved outcomes, with decreased rate of Caesarean section, better glycaemic control and better neonatal Apgar scores. Women with diabetes should not smoke during pregnancy because of the increased risk of miscarriage and poorer glycaemic control.

History of the enzyme nomenclature system

Naming things is essential for people to understand one another, no matter what language or field of interest is involved. This is as true for enzymes, genes and chemicals as it is for birds, food, flowers, etc. Effective communication requires a lack of ambiguity, but, in practice, ambiguities abound even between people who use the same language in different parts of the world, or even within the same country. Whereas ambiguities in the words used for common objects or actions have been the basis for many, more-or-less memorable jokes, they can also cause a great deal of confusion. Such linguistic chaos is welcomed by many as being a part of a diverse heritage that should be preserved at all costs to prevent us from descending into Orwellian 'newspeak'. However, in the sciences, there are distinct advantages in others being able to understand what one is doing. Many groups have stressed the need for standardized, universally accepted systems of nomenclature in chemistry, genetics, enzymology, etc. However, it is the universal acceptance that usually causes the problem. It is rare to find people who will admit that they find nomenclature to be an interesting subject, but many who profess contempt for it will get very excited if it is suggested that their pet nomenclature should be changed in the interest of clarity or uniformity. This account will consider the development of the enzyme nomenclature system, its benefits, shortcomings and future prospects.

Possible antimigraine mechanisms of action of the 5HT1F receptor agonist LY334370

This study investigated whether the selective 5HT1F receptor agonist LY334370 has other possible antimigraine mechanisms in addition to the proposed inhibition of dural plasma extravasation. LY334370 (up to 10(-5) M) had no vasoconstrictor effects on human cerebral arteries in vitro. It had no effect (up to 10 mg kg-1, i.v.) on neurogenic vasodilation of dural blood vessels produced by electrical stimulation of the dura mater in anesthetized rats. Nor had it any effect (at 3 mg kg-1, i.v.) on the hyperalgesia produced by injection of carrageenan into the paw of conscious rats or on nociceptive reflex responses in the spinalized, decerebrate rabbit (up to 3 mg kg-1, i.v.), indicating that it has no general analgesic properties. However, it significantly inhibited activation of second-order neurons in the trigeminal nucleus caudalis produced by electrical stimulation of the dura mater in anesthetised rats at 3 mg kg-1, i.v. These results provide evidence to suggest that LY334370 has a central mechanism of action in blocking the transmission of nociceptive impulses within the trigeminal nucleus caudalis and that this may represent a mechanism through which it has its antimigraine effect.

SAR in the alkoxy lactone series: the discovery of DFP, a potent and orally active COX-2 inhibitor

Extensive SAR has been established in the alkoxy lactone series and this has lead to the discovery of DFP (5,5-dimethyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanon e), a potent COX-2 inhibitor exhibiting in vivo efficacy in all models studied.

Rofecoxib [Vioxx, MK-0966; 4-(4'-methylsulfonylphenyl)-3-phenyl-2-(5H)-furanone]: a potent and orally active cyclooxygenase-2 inhibitor. Pharmacological and biochemical profiles

The discoveries that cyclooxygenase (COX)-2 is an inducible form of COX involved in inflammation and that COX-1 is the major isoform responsible for the production of prostaglandins (PGs) in the gastrointestinal tract have provided a rationale for the development of specific COX-2 inhibitors as a new class of anti-inflammatory agents with improved gastrointestinal tolerability. In the present study, the preclinical pharmacological and biochemical profiles of rofecoxib [Vioxx, also known as MK-0966, 4-(4'-methylsulfonylphenyl)-3-phenyl-2-(5H)-furanone], an orally active COX-2 inhibitor, are described. Rofecoxib is a potent inhibitor of the COX-2-dependent production of PGE(2) in human osteosarcoma cells (IC(50) = 26 +/- 10 nM) and Chinese hamster ovary cells expressing human COX-2 (IC(50) = 18 +/- 7 nM) with a 1000-fold selectivity for the inhibition of COX-2 compared with the inhibition of COX-1 activity (IC(50) > 50 microM in U937 cells and IC(50) > 15 microM in Chinese hamster ovary cells expressing human COX-1). Rofecoxib is a time-dependent inhibitor of purified human recombinant COX-2 (IC(50) = 0.34 microM) but caused inhibition of purified human COX-1 in a non-time-dependent manner that could only be observed at a very low substrate concentration (IC(50) = 26 microM at 0.1 microM arachidonic acid concentration). In an in vitro human whole blood assay, rofecoxib selectively inhibited lipopolysaccharide-induced, COX-2-derived PGE(2) synthesis with an IC(50) value of 0.53 +/- 0.02 microM compared with an IC(50) value of 18.8 +/- 0.9 microM for the inhibition of COX-1-derived thromboxane B(2) synthesis after blood coagulation. Using the ratio of the COX-1 IC(50) values over the COX-2 IC(50) values in the human whole blood assay, selectivity ratios for the inhibition of COX-2 of 36, 6.6, 2, 3, and 0.4 were obtained for rofecoxib, celecoxib, meloxicam, diclofenac, and indomethacin, respectively. In several in vivo rodent models, rofecoxib is a potent inhibitor of carrageenan-induced paw edema (ID(50) = 1.5 mg/kg), carrageenan-induced paw hyperalgesia (ID(50) = 1.0 mg/kg), lipopolysaccharide-induced pyresis (ID(50) = 0.24 mg/kg), and adjuvant-induced arthritis (ID(50) = 0.74 mg/kg/day). Rofecoxib also has a protective effect on adjuvant-induced destruction of cartilage and bone structures in rats. In a (51)Cr excretion assay for detection of gastrointestinal integrity in either rats or squirrel monkeys, rofecoxib has no effect at doses up to 200 mg/kg/day for 5 days. Rofecoxib is a novel COX-2 inhibitor with a biochemical and pharmacological profile clearly distinct from that of current nonsteroidal anti-inflammatory drugs and represents a new therapeutic class of anti-inflammatory agents for the treatment of the symptoms of osteoarthritis and rheumatoid arthritis with improved gastrointestinal tolerability.

The tetrodotoxin-resistant sodium channel SNS has a specialized function in pain pathways

Many damage-sensing neurons express tetrodotoxin (TTX)-resistant voltage-gated sodium channels. Here we examined the role of the sensory-neuron-specific (SNS) TTX-resistant sodium channel alpha subunit in nociception and pain by constructing sns-null mutant mice. These mice expressed only TTX-sensitive sodium currents on step depolarizations from normal resting potentials, showing that all slow TTX-resistant currents are encoded by the sns gene. Null mutants were viable, fertile and apparently normal, although lowered thresholds of electrical activation of C-fibers and increased current densities of TTX-sensitive channels demonstrated compensatory upregulation of TTX-sensitive currents in sensory neurons. Behavioral studies demonstrated a pronounced analgesia to noxious mechanical stimuli, small deficits in noxious thermoreception and delayed development of inflammatory hyperalgesia. These data show that SNS is involved in pain pathways and suggest that blockade of SNS expression or function may produce analgesia without side effects.

Selective NMDA NR2B antagonists induce antinociception without motor dysfunction: correlation with restricted localisation of NR2B subunit in dorsal horn

The present study investigated the regional distribution of the N-methyl-D-aspartate (NMDA) receptor containing the NR2B subunit protein in rat lumbar spinal cord and examined whether selective NR2B antagonists would exhibit antinociception with reduced side-effect liability than subtype non-selective NMDA antagonists and anticonvulsants. Immunocytochemical studies showed the NR2B subunit had a restricted distribution, with moderate labelling of fibres in laminas I and II of the dorsal horn suggesting a presynaptic location on primary afferent fibers and possible involvement in pain transmission. In the in vivo studies, the NMDA/glycine antagonists (MK-801, 0.02-1 mg/kg i.p., L-687,414 10-300 mg/kg i.p., and L-701,324 1-10 mg/kg i.p.) and the anticonvulsant, gabapentin (10-500 mg/kg p.o.), induced rotarod deficits at antinociceptive doses. In contrast, the selective NR2B antagonists, (+/-)-CP-101,606 (1-100 mg/kg p.o.) and (+/-)-Ro 25-6981 (3-100 mg/kg i.p.) showed a significant dose window. (+/-)-CP-101,606 caused no motor impairment or stimulation in rats at doses up to 100 mg/kg p.o., which is far in excess of those inhibiting allodynia in neuropathic rats (ID50 4.1 mg/kg, p.o.). (+/-)-Ro 25-6981 also showed a significant separation (ID50 allodynia 3.8 mg/kg, i.p.), however, some disruption of rotarod performance was observed at 100 mg/kg. The anticonvulsant lamotrigine (3-500 mg/kg p.o.) also showed a good dose window. These findings demonstrate that NR2B antagonists may have clinical utility for the treatment of neuropathic and other pain conditions in man with a reduced side-effect profile than existing NMDA antagonists.

Age-related cognitive deficits, impaired long-term potentiation and reduction in synaptic marker density in mice lacking the beta-amyloid precursor protein

Mutations in the beta-amyloid precursor protein are strongly associated with some cases of familial Alzheimer's disease. The normal physiological role of beta-amyloid precursor protein in the brain was evaluated in a cross-sectional analysis of mice deficient in beta-amyloid precursor protein. Compared with wild-type control mice the beta-amyloid precursor protein-null mice developed age-dependent deficits in cognitive function and also had impairments in long-term potentiation. In addition, the brains of the beta-amyloid precursor protein-null mice had marked reactive gliosis in many areas, especially in the cortex and hippocampus. A subpopulation of mice (n = 15) died prematurely (between three and 18 months of age). Analysis of another six mice from the same population that were showing weight loss and hypolocomotor activity exhibited a marked reactive gliosis as detected by immunoreactivity for glial fibrillary acidic protein and a profound loss of immunoreactivities for the presynaptic terminal vesicle marker proteins synaptophysin and synapsin and the dendritic marker microtubule-associated protein-2 in many brain areas, but most predominantly in the cortex and hippocampus. These results suggest that normal beta-amyloid precursor protein may serve an essential role in the maintenance of synaptic function during ageing. A compromise of this function of the beta-amyloid precursor protein may contribute to the progression of the memory decline and the neurodegenerative changes seen in Alzheimer's disease.