The antimicrobial peptide cathelicidin drives development of experimental autoimmune encephalomyelitis in mice by affecting Th17 differentiation

Multiple sclerosis (MS) is a highly prevalent demyelinating autoimmune condition; the mechanisms regulating its severity and progression are unclear. The IL-17-producing Th17 subset of T cells has been widely implicated in MS and in the mouse model, experimental autoimmune encephalomyelitis (EAE). However, the differentiation and regulation of Th17 cells during EAE remain incompletely understood. Although evidence is mounting that the antimicrobial peptide cathelicidin profoundly affects early T cell differentiation, no studies have looked at its role in longer-term T cell responses. Now, we report that cathelicidin drives severe EAE disease. It is released from neutrophils, microglia, and endothelial cells throughout disease; its interaction with T cells potentiates Th17 differentiation in lymph nodes and Th17 to exTh17 plasticity and IFN-γ production in the spinal cord. As a consequence, mice lacking cathelicidin are protected from severe EAE. In addition, we show that cathelicidin is produced by the same cell types in the active brain lesions in human MS disease. We propose that cathelicidin exposure results in highly activated, cytokine-producing T cells, which drive autoimmunity; this is a mechanism through which neutrophils amplify inflammation in the central nervous system.

Abstract 2162: Inhibition of GPR65 counteracts low pH induced immunosuppressive polarization of macrophages: In vitro and in vivo characterization of potent, selective and orally bioavailable small molecule GPR65 antagonists

The acidic tumour microenvironment (TME) and the abundance of tumour associated macrophages (TAMs) are key features of solid tumours that drive immune suppression, support tumour growth and limit the efficacy of approved therapies. We identified the pH sensing GPCR, GPR65, as a key determinant of low pH induced immune suppression in human cancers, particularly in TAMs, based on the following observations: 1) cancer patients who are homozygous for a hypomorphic coding variant in GPR65 (I231L) show a statistically significant increase in survival and altered expression of key immune system genes compared to other genotypes; 2) single cell RNA sequencing (scRNAseq) data from multiple solid tumors show that GPR65 and downstream pathway genes are ubiquitously expressed in myeloid and other innate immune cells in human cancers; and 3) low pH acting via GPR65 profoundly alters gene expression in human macrophages in vitro, bringing about a pronounced suppression of proinflammatory cytokines and a marked upregulation of tissue repair genes. These findings identify GPR65 as a novel innate immune check point, and suggest that GPR65 inhibition could be highly beneficial in cancer. Indeed, previous work has shown that genetic ablation of the GPR65 signaling pathway in B16.F10 tumour bearing mice upregulates immunostimulatory genes in TAMs and significantly reduces tumor growth1. Pathios has identified potent and selective antagonists of human GPR65 with excellent oral bioavailability and pharmacokinetics. In line with their potencies in recombinant cell systems, lead molecules are able to inhibit low pH induced cAMP elevations in primary human macrophages with IC50 values in the single digit nM range. In macrophages subjected to acidic conditions, the inhibitory effects on cAMP are accompanied by a reduction in the expression of anti inflammatory and tissue repair genes, and the enhancement of immunostimulatory genes. In particular, GPR65 inhibition counteracts the pronounced low pH induced suppression of key Type I/II interferon (IFN) response genes and chemokines such as CXCL9, CXCL10 and CXCL11. Following oral administration in tumour bearing mice, lead compounds up-regulate the expression of anti-tumor immune response genes at systemic exposures that significantly suppress GPR65 signalling in vitro. Results from tumour growth inhibition studies in mice with our GPR65 inhibitors will be also be presented. In summary, ‘Macrophage Conditioning’ via GPR65 inhibition holds substantial promise as a novel immunoncology strategy to counteract the immunosuppressive effects of the acidic TME on TAMs, and could be deployed either as monotherapy or in combination with T cell checkpoint inhibitors or other standard of care treatments. 1Nat. Immunol. 19:1319

Citation Format: Barbara Cipriani, David Miller, Alan Naylor, Gavin Milne, Barbara Young, Rupert Satchell, Suorav Sarkar, Zoe Smith, Rhoanne McPherson, Anastasia Nika, Preeti Singh, Toszka Bohn, Tobias Bopp, Tom McCarthy, Stuart Hughes. Inhibition of GPR65 counteracts low pH induced immunosuppressive polarization of macrophages: In vitro and in vivo characterization of potent, selective and orally bioavailable small molecule GPR65 antagonists [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2162.

Abstract 5586: Demonstrating restoration of T cell function in exhausted T cells with IKZF3 small molecule inhibitor, Lenalidomide

CD8+ T cell exhaustion as a result of prolonged antigenic stimulation in the tumour microenvironment is thought to be a major mechanism by which tumours can escape immune surveillance. T cell exhaustion is characterised by co-expression of checkpoint inhibitor molecules such as PD-1, LAG-3 and TIM-3; reduced proliferative capacity; and diminished production of pro-inflammatory cytokines such as IL-2, IFN-γ and TNF-α and treatment with checkpoint inhibitor blockade such as Nivolumab (anti-PD-1) have shown great promise in the treatment of a subset of individuals and tumour types. However, resistance to these approaches is prevalent and there is a need to identify novel targets to provide alternative options for the rescue of T cell exhaustion and cancer treatment for use alone or potentially in combination with checkpoint inhibitor modulation. One such target is IKZF3, a transcription factor that is increased in murine models of T cell exhaustion and reduces IL-2 expression. Previously we presented an in vitro human T cell exhaustion assay whereby in vitro stimulated T cells phenotypically and functionally recapitulate the exhausted T cells found within the tumour microenvironment and now we demonstrate that exhaustion can be partially rescued by treatment with the IKZF3 small molecule inhibitor, Lenalidomide, alone and in combination with checkpoint inhibitor blockade. The use of small molecule inhibitors offers new avenues for reversing T cell exhaustion in cases of checkpoint inhibitor resistance and this platform delivers a robust assay allowing for assessment of small molecules or checkpoint inhibitors both individually and in combination.

Citation Format: Joanne Hay, Francis Acklam, Darryl Turner, Mark Barbour, Preeti Singh, Courtney Grant, Hayley Gooding, Rhoanne McPherson, Justyna Rzepecka. Demonstrating restoration of T cell function in exhausted T cells with IKZF3 small molecule inhibitor, Lenalidomide [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5586.

Abstract 419: The development of BRPF1 degraders as a potential treatment for acute myeloid leukemia

Acetylation of histones and additional nuclear proteins is a key mechanism in the regulation of gene expression. Aberrant acetylation has been linked to a wide range of diseases including cancer, inflammation, and neurodevelopmental disorders. Histone acetylation is introduced by histone acetyltransferases complexes (HATs), where substrate specificity is dramatically enhanced by scaffolding proteins that activate and target them to specific chromatin sites. A protein of interest with both epigenetic acetyl reader and scaffolding function is the protein Bromodomain and PHD finger-containing protein 1 (BRPF1). The Protein contains domains of two plant homeodomain (PHD) fingers separated by a zinc knuckle (PZP domain), a bromodomain, and a proline-tryptophan-tryptophan-proline (PWWP) Tudor domain. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as the catalytic MYST-family acetyltransferase subunit and the stable complex with Moz-Tif2 is known to lead to the development of human acute myeloid leukemia (AML). Given this, we chose to pursue the development of BRPF1 degraders to probe cancer disease biology especially in AML, where new therapies are required to overcome several unmet needs such as less-toxic treatments and relapsed/refractory disease paradigms. Here we present the design and synthesis of a range of BRPF1 degraders in highly desirable physicochemical space utilizing in-silico modeling. The prepared degraders which utilize multiple E3 ligases were then screened against cell lines harboring Mixed-lineage leukemia (MLL) translocations specifically the THP-1 cell line. In addition to this, we investigated the ability of the compounds to effectively degrade the target and suitability of our degraders for potential in-vivo exposure through a panel of routine ADMET assays.

Citation Format: Daniel Joseph Glynn, Rosie Crampton, Thomas Pesnot, Andrew Scott, Anne-Chloe Nassoy, Ralph Kirk, Daniele Narducci, Gary Nelson, Lynette Ongiri, Habiba Begum, Vincent Rao, Matilda Bingham, Rhoanne McPherson, Darryl Turner. The development of BRPF1 degraders as a potential treatment for acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 419.

251 The use of small molecule inhibitors to target novel pathways in exhausted T cells for immuno-oncology therapeutic intervention

Background

The ability to reverse exhaustion in CD8+ T cells holds great promise for therapeutic intervention in oncology. Indeed, treatment with therapeutics targeted at checkpoint inhibitors, such as Nivolumab (anti-PD-1), have shown great promise in the treatment of a subset of individuals and tumour types. However, pre-clinical success does not always translate to success in clinical trials and resistance to these approaches is prevalent. As such, there is a pressing need to develop novel approaches that target alternative pathways for use alone or potentially in combination with checkpoint inhibitor modulation. A secondary need is the requirement for advanced assays that accurately recapitulate the pathways and cell phenotypes prevalent in the tumour environment.

Methods

Here we describe the characteristics of an in vitro human T cell exhaustion assay whereby in vitro stimulated T cells phenotypically and functionally recapitulate the exhausted T cells found within the tumour microenvironment. We also demonstrate the effect of checkpoint blockade as well as small molecule inhibition of a novel target on the exhausted T cell phenotype.

Results

In this assay, exhaustion can be partially but not fully reversed by treatment with anti-PD-1 alone. In addition, we demonstrate the effect of a small molecule inhibitor targeting IKZF3, a transcription factor shown to be upregulated in T cell exhaustion, on reversing T cell exhaustion alone and in combination with checkpoint inhibitor blockade.

Conclusions

These assays and approaches enable investigation into the ability of compounds to influence reversal of T cell exhaustion where anti-PD-1 treatment does not fully reverse the exhausted phenotype and offers the ability to test combination therapy approaches.

Acknowledgements

This work was aided by the valuable input and insight of Professor Stephen Anderton.

Ethics Approval

The study obtained ethics approval from West Midlands – Black Country Research Ethics Committee under IRAS project ID 270936. All donors gave informed consent before taking part.

Abstract LB158: Implications of Targeting Novel Pathways in Exhausted T Cells for Immuno-Oncology Therapeutic Intervention

The induction of CD8+ T cell exhaustion, driven by the tumor microenvironment, is thought to be a major mechanism by which tumors can escape immune surveillance and are able to persist and progress. T cell exhaustion is typically characterized by the expression of co-inhibitory markers such as PD-1, LAG-3 and TIM-3 and a reduced capacity for pro-inflammatory cytokine production. Whilst treatment with therapeutics targeted at checkpoint inhibitors, such as Nivolumab (anti-PD-1), have shown great promise in the treatment of a subset of individuals and tumor types, resistance to these approaches is prevalent. As such, novel approaches are required in order to provide alternative options for the rescue of T cell exhaustion and cancer treatment.

Here we describe the characteristics of an in vitro human T cell exhaustion assay whereby in vitro stimulated T cells phenotypically and functionally recapitulate the exhausted T cells found within the tumor microenvironment and where exhaustion can be partially rescued by treatment with anti-PD-1. Furthermore, we demonstrate the effect of treatment with an inhibitor of a novel target identified in exhausted T cells on T cell function; both through analysis of pro-inflammatory cytokine production and the ability to kill tumor cells. These assays and approaches enable investigation into the ability of compounds to influence reversal of T cell exhaustion where anti-PD-1 treatment does not fully reverse the exhausted phenotype and offers the ability to test combination therapy approaches.

Citation Format: Rhoanne McPherson, Francis Acklam, Joanne Hay, Mark Barbour, Courtney Grant, Preeti Singh, Adriana Gambardella, Justyna Rzepecka, Stephen Anderton, Hayley Gooding. Implications of Targeting Novel Pathways in Exhausted T Cells for Immuno-Oncology Therapeutic Intervention [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 LB158.

Abstract 1631: GPR65 is a critical mediator of low pH induced immunosuppressive signalling in tumor associated macrophages: Human target validation of GPR65 as a novel innate immune checkpoint and discovery of potent, selective GPR65 antagonists

Tumor-associated macrophages (TAMs) are the major innate immune component in the microenvironment of solid tumors. These cells are highly heterogeneous and plastic but often display a pronounced immunosuppressive phenotype that supports primary tumor growth and metastasis. A recently identified determinant of the immunosuppressive properties of TAMs is the activation of the pH-sensing G protein-coupled receptor, GPR65, on these cells by the acidic microenvironment that is inherent to many advanced solid tumours1. Previous work in mouse macrophages has shown that GPR65 activation leads to an elevation of inducible cAMP early repressor (ICER), an isoform of the CREM gene, which in turn suppresses the expression of a host of proinflammatory mediators1. Consistent with a high expression of GPR65 and CREM in human myeloid cells, and particularly in human TAMs, we now show that equivalent immunosuppressive signaling is also present in human macrophages in response to low pH. Further substantiating GPR65 as an innate immune checkpoint in human cancers, we also show that subjects that are homozygous for a hypomorphic coding variant in GPR65 (I231L) have a significantly improved survival across a range of cancers compared to other genotypes. This survival advantage is maintained in patients with highly glycolytic tumors that would otherwise be predicted to respond poorly to immunotherapy, and is consistent with studies showing that genetic deletion of ICER attenuates the growth of anti-PD-1-resistant B16.F10 melanoma tumors in mice1. With a view to developing a therapeutic agent able to reverse low pH-dependent immunosuppression in TAMs, we identified potent and selective small molecule inhibitors of GPR65 from a screening campaign. These molecules were able to fully ablate the acidic pH-induced expression of ICER in human macrophages with downstream implications for pro-inflammatory cytokines known to support T cell anti-tumor responses. Additional medicinal chemistry optimization led to molecules exhibiting excellent oral bioavailability in preclinical species and systemic exposure that completely suppressed GPR65 signaling following oral dosing in mice. Profiling of these inhibitors in relevant mouse tumor models is currently ongoing. In conclusion, we have (i) demonstrated that GPR65 is a key determinant of low pH-induced immunosuppression in human macrophages and thus an important innate immune checkpoint in cancer, and (ii) identified selective small molecule inhibitors of GPR65 with potent in vivo activity. This work provides the basis for developing novel “macrophage conditioning” therapeutic agents that may have utility across a range of cancers, either as single agents or in combination with other approved immunoncology drugs. 1Nat Immunol 19:1319.

Citation Format: Barbara Cipriani, Alan Naylor, Gavin Milne, Barbara Young, Rupert Satchell, Sourav Sarkar, Zoe Smith, Louise Healy, John Unitt, Jessica Holien, Rhoanne McPherson, Anastasia Nika, Jessy Cartier, Tozska Bohn, Tobias Bopp, Tom McCarthy, Stuart Hughes. GPR65 is a critical mediator of low pH induced immunosuppressive signalling in tumor associated macrophages: Human target validation of GPR65 as a novel innate immune checkpoint and discovery of potent, selective GPR65 antagonists [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 1631.

A prospective randomized evaluation of a pharmacogenomic approach to antiplatelet therapy among patients with ST-elevation myocardial infarction: the RAPID STEMI study

Treatment of carriers of the CYP2C19*2 allele and ABCB1 TT genotype with clopidogrel is associated with increased ischemic complications after percutaneous coronary intervention (PCI). We sought to evaluate a pharmacogenomic strategy among patients undergoing PCI for ST-elevation myocardial infarction (STEMI), by performing a randomized trial, enrolling 102 patients. Point-of-care genetic testing for CYP2C19*2, ABCB1 TT and CYP2C19*17 was performed with carriers of either the CYP2C19*2 allele or ABCB1 TT genotype randomly assigned to a strategy of prasugrel 10 mg daily or an augmented dosing strategy of clopidogrel (150 mg daily for 6 days then 75 mg daily). The primary end point was the proportion of at-risk carriers exhibiting high on-treatment platelet reactivity (HPR), a marker associated with increased adverse cardiovascular events, after 1 month. Fifty-nine subjects (57.8%) were identified as carriers of at least one at-risk variant. Treatment with prasugrel significantly reduced HPR compared with clopidogrel by P2Y12 reaction unit (PRU) thresholds of >234 (0 vs 24.1%, P=0.0046) and PRU>208 (3.3 vs 34.5%, P=0.0025). The sensitivity of point-of-care testing was 100% (95% CI 88.0-100), 100% (86.3-100) and 96.9% (82.0-99.8) and specificity was 97.0% (88.5-99.5), 97.1% (89.0-99.5) and 98.5% (90.9-99.9) for identifying CYP2C19*2, ABCB1 TT and CYP2C19*17, respectively. Logistic regression confirmed carriers as a strong predictor of HPR (OR=6.58, 95% CI 1.24-34.92; P=0.03). We confirmed that concurrent identification of three separate genetic variants in patients with STEMI receiving PCI is feasible at the bedside. Among carriers of at-risk genotypes, treatment with prasugrel was superior to an augmented dosing strategy of clopidogrel in reducing HPR.

Naturally occurring R225W mutation of the gene encoding AMP-activated protein kinase (AMPK)gamma(3) results in increased oxidative capacity and glucose uptake in human primary myotubes

AIMS/HYPOTHESIS

AMP-activated protein kinase (AMPK) has a broad role in the regulation of glucose and lipid metabolism making it a promising target in the treatment of type 2 diabetes mellitus. We therefore sought to characterise for the first time the effects of chronic AMPK activation on skeletal muscle carbohydrate metabolism in carriers of the rare gain-of-function mutation of the gene encoding AMPKgamma(3) subunit, PRKAG3 R225W.

METHODS

Aspects of fuel metabolism were studied in vitro in myocytes isolated from vastus lateralis of PRKAG3 R225W carriers and matched control participants. In vivo, muscular strength and fatigue were evaluated by isokinetic dynamometer and surface electromyography, respectively. Glucose uptake in exercising quadriceps was determined using [(18)F]fluorodeoxyglucose and positron emission tomography.

RESULTS

Myotubes from PRKAG3 R225W carriers had threefold higher mitochondrial content (p < 0.01) and oxidative capacity, higher leak-dependent respiration (1.6-fold, p < 0.05), higher basal glucose uptake (twofold, p < 0.01) and higher glycogen synthesis rates (twofold, p < 0.05) than control myotubes. They also had higher levels of intracellular glycogen (p < 0.01) and a trend for lower intramuscular triacylglycerol stores. R225W carriers showed remarkable resistance to muscular fatigue and a trend for increased glucose uptake in exercising muscle in vivo.

CONCLUSIONS/INTERPRETATION

Through the enhancement of skeletal muscle glucose uptake and increased mitochondrial content, the R225W mutation may significantly enhance exercise performance. These findings are also consistent with the hypothesis that the gamma(3) subunit of AMPK is a promising tissue-specific target for the treatment of type 2 diabetes mellitus, a condition in which glucose uptake and mitochondrial function are impaired.

Testing a scalable community-based approach to improve maternal and neonatal health in rural Nepal

OBJECTIVE

The aim of the study was to determine the feasibility of improved maternal-neonatal care-seeking and household practices using an approach scalable under Nepal's primary health-care services.

STUDY DESIGN

Impact was assessed by pre- and post-intervention surveys of women delivering within the previous 12 months. Each district sample comprised 30 clusters, each with 30 respondents. The intervention consisted primarily of community-based antenatal counseling and dispensing and an early postnatal home visit; most activities were carried out by community-based health volunteers.

RESULT

There were notable improvements in most household practice and service utilization indicators, although results regarding care-seeking for danger signs were mixed.

CONCLUSION

It is feasible in a Nepal setting to significantly improve utilization of maternal-neonatal services and household practices, using the resources available under the government primary health-care system. This has the potential to significantly reduce neonatal mortality.

Increased susceptibility to oxidative damage in post-diabetic human myotubes

AIMS/HYPOTHESIS

Obesity is an important risk factor for the development of type 2 diabetes, but not all obese individuals develop this complication. The clinical signs of type 2 diabetes can often be reversed with weight loss; however, it is unknown whether the skeletal muscle oxidative stress associated with type 2 diabetes remains after weight loss. We hypothesised that chronic exposure to high glucose and insulin would re-elicit impaired metabolism in primary myotubes from patients with a history of type 2 diabetes.

METHODS

Obese participants with or without type 2 diabetes completed a standardised weight loss protocol, following which all participants were euglycaemic and had similar indices of insulin sensitivity. Satellite cells were isolated from muscle biopsies and differentiated under low or high glucose and insulin conditions (HGI).

RESULTS

Cells from participants with no history of type 2 diabetes showed robust increases in mitochondrial content, citrate synthase and cytochrome c oxidase activities when exposed to HGI. This increase in oxidative capacity was absent in cells from patients with a history of type 2 diabetes. High glucose and insulin caused increased oxidative damage in cells from the latter, despite higher superoxide dismutase expression. Cells from patients with a history of type 2 diabetes were unable to decrease mitochondrial membrane potential in response to HGI, potentially due to lower levels of uncoupling protein-3.

CONCLUSIONS/INTERPRETATION

This is the first report to note that primary myotubes from patients with a history of type 2 diabetes are unable to adapt to a hyperglycaemic-hyperinsulinaemic challenge. We have demonstrated that impaired mitochondrial biogenesis and an inability to manage oxidative stress define a muscle phenotype at risk of obesity-associated type 2 diabetes.

Vascular calcifications in homozygote familial hypercholesterolemia

BACKGROUND

Patients with homozygous familial hypercholesterolemia (hmzFH) attributable to LDL receptor gene mutations have shown a remarkable increase in survival over the last 20 years. Early onset coronary heart disease (CHD) and calcific aortic valve stenosis are the major complications of this disorder. We now report extensive premature calcification of the aorta in patients with hmzFH.

METHODS AND RESULTS

We examined 25 hmzFH patients from Canada; mean age was 32 years (range 5 to 54), and mean baseline cholesterol before treatment was 19+/-5 mmol/L (737+/-206 mg/dL). Aortic calcification was quantified using computed tomography (CT). An elevated mean calcium score was found in patients by age 20 and correlated with age (r(2)=0.53, P=0.001). One quarter (24%) of patients underwent aortic valve surgery.

CONCLUSIONS

We document premature severe aortic calcifications in all adult hmzFH patients studied. These presented considerable surgical management challenges. Strategies to identify and monitor aortic calcification in hmzFH by noninvasive techniques are required, as are clinical trials to determine whether additional or more intensive therapies will prevent the progression of such calcifications. Whether vascular calcifications in hmzFH subjects are related to sustained increases in LDL-C levels or to other mechanisms, such as abnormal osteoblast activity, remains to be determined.

Automated sample exchange and tracking system for neutron research at cryogenic temperatures

An automated system for sample exchange and tracking in a cryogenic environment and under remote computer control was developed. Up to 24 sample "cans" per cycle can be inserted and retrieved in a programed sequence. A video camera acquires a unique identification marked on the sample can to provide a record of the sequence. All operations are coordinated via a LABVIEW program that can be operated locally or over a network. The samples are contained in vanadium cans of 6-10 mm in diameter and equipped with a hermetically sealed lid that interfaces with the sample handler. The system uses a closed-cycle refrigerator (CCR) for cooling. The sample was delivered to a precooling location that was at a temperature of approximately 25 K, after several minutes, it was moved onto a "landing pad" at approximately 10 K that locates the sample in the probe beam. After the sample was released onto the landing pad, the sample handler was retracted. Reading the sample identification and the exchange operation takes approximately 2 min. The time to cool the sample from ambient temperature to approximately 10 K was approximately 7 min including precooling time. The cooling time increases to approximately 12 min if precooling is not used. Small differences in cooling rate were observed between sample materials and for different sample can sizes. Filling the sample well and the sample can with low pressure helium is essential to provide heat transfer and to achieve useful cooling rates. A resistive heating coil can be used to offset the refrigeration so that temperatures up to approximately 350 K can be accessed and controlled using a proportional-integral-derivative control loop. The time for the landing pad to cool to approximately 10 K after it has been heated to approximately 240 K was approximately 20 min.

Safety of Triamcinolone acetonide (TA)-assisted pars plana vitrectomy in macular hole surgery

AIM

To evaluate whether Triamcinolone acetonide (TA)-assisted pars plana vitrectomy for visualisation of posterior hyaloid during macular hole surgery has any adverse effects on macular hole closure rate and intraocular pressure (IOP).

METHODS

Case series comparing outcomes and adverse effects in patients who had surgery for macular holes with ILM peel, with and without the use of TA-assisted vitrectomy.

RESULTS

During the study period, 29 patients had vitrectomy for macular holes. In 18 patients (group 1), TA was used intraoperatively to facilitate visualisation of the posterior hyaloid and in 11 patients (group 2) no TA was used. There was no statistically significant difference in the macular hole closure rates and the improvement in visual acuity between the two groups. No long-term increase in IOP was recorded in any of the 29 patients. The total anatomical success rate in both groups was 85.6% and the average improvement in visual acuity in both groups was two Snellen lines.

CONCLUSIONS

TA is safe and there is no contraindication for its use as an intraoperative aid to facilitate vitreous visualisation in macular hole surgery.

The low density lipoprotein receptor-related protein contributes to selective uptake of high density lipoprotein cholesteryl esters by SW872 liposarcoma cells and primary human adipocytes

The concept that selective transfer of high density lipoprotein (HDL)-derived cholesteryl esters (CE) does not require lipoprotein internalization has been challenged recently by evidence that implicates HDL recycling during the selective uptake process. This has prompted us to examine the role of the low density lipoprotein receptor-related protein (LRP) in selective uptake. LRP is an endocytic receptor for lipoprotein lipase (LpL) and apolipoprotein E (apoE) ligands that are able to mediate selective uptake. We report that molecules that interfere with ligand binding to LRP, such as the receptor-associated protein (RAP), suramin, alpha(2)-macroglobulin, or lactoferrin, inhibit HDL-CE selective uptake by human primary adipocytes and SW872 liposarcoma cells by 35-50%. This partial inhibition of selective uptake from total HDL was not due to preferential inhibition of the HDL(2) or HDL(3) subfractions. Selective uptake by the scavenger receptor BI was not inhibited by RAP, excluding its involvement. Furthermore, in SW872 cells in which LRP was reduced to 14% of control levels by stable antisense expression, selective uptake was attenuated by at least 33%, confirming a role for LRP in this process. RAP, alpha(2)-macroglobulin, lactoferrin, and suramin (individually or in paired combinations) also attenuated selective uptake of HDL-CE by primary human adipocytes by about 40%. On the other hand, human skin fibroblasts express LRP abundantly but lack the capacity for selective uptake, demonstrating that other molecules are required. In SW872 cells, exogenous apoE or LpL can facilitate selective uptake but only the apoE-enhanced uptake can be inhibited by RAP, implicating apoE as a likely co-mediator. We discuss the possible mechanisms by which the endocytic receptor, LRP, can mediate selective uptake.

Adaptive hypersensitivity to estradiol: potential mechanism for secondary hormonal responses in breast cancer patients

Women with hormone dependent breast cancer initially respond to hormone deprivation therapy with tamoxifen or oophorectomy for 12-18 months but later relapse. Upon secondary therapy with aromatase inhibitors, patients often experience further tumor regression. The mechanisms responsible for secondary responses are unknown. We postulated that hormone deprivation induces hypersensitivity to estradiol. Evidence of this phenomenon was provided in a model system involving MCF-7 cells grown in vitro and in xenografts. To determine if the ER transcriptional process is involved in hypersensitivity, we examined the effect of estradiol on ER reporter activity, PgR, PS2, and c-myc as markers and found no alterations in hypersensitive cells. Next, we examined whether MAP kinase may be upregulated in the hypersensitive cells as a reflection of increased growth factor secretion or action. Basal MAP kinase activity was increased both in vitro and in vivo in hypersensitive cells. Proof of principle studies indicated that an increase in MAP kinase activity induced by TGFalpha administration caused a two- to three-fold shift to the left in estradiol dose response curves in wild type cells. Blockade of MAP kinase with PD98059 returned the shifted curve back to baseline. These data suggested that MAP kinase overexpression could induce hypersensitivity. To determine why MAP kinase was increased, we excluded constitutive receptor activity and growth factor secretion by the demonstration that the pure anti-estrogen, ICI 182780, could inhibit MAP kinase activation. We also excluded hypersensitivity to estradiol induced growth factor secretion, and thus MAP kinase activation, since estradiol stimulated MAP kinase at 24, 48, and 72 h at the same concentrations in hypersensitive as in wild type cells. Surprisingly, a series of experiments suggested that MAP kinase increased in hypersensitive cells as a result of estrogen activation via a non-genomic pathway. We examined the classical signal pathway in which SHC is phosphorylated and binds to SOS and GRB-2 to activate Ras, Raf, and MAP kinase. With 5-20 min of exposure, estradiol caused binding of SHC to the estrogen receptor, phosphorylation of SHC, binding of GRB-2 to SOS, and activation of MAP kinase. All of these affects could be blocked by ICI 182780. Taken together, these observations suggest that the cell membrane ER pathway may be responsible for upregulation of MAP kinase and hypersensitivity in cells adapted to estradiol deprivation.

The bioaccumulation of cadmium by the Blue Swimmer Crab Portunus pelagicus L

The Blue Swimmer Crab (Portunus pelagicus) accumulates only cadmium in the hepatopancreas after being presented elevated levels of the metals Cd, Cu, Zn, As, Fe and Al via a food source, the mussel Trychomya hirsuta. Over 8 weeks, crabs were fed a controlled diet to determine the accumulation of metals. Significant (P = 0.05) Cd accumulation was detected after 4 weeks of feeding. Food mussels were sourced from either 'contaminated' or 'uncontaminated' sites. Mussels from uncontaminated sites had an average Cd level of 0.07 microg/g wet weight and contaminated mussels had an average of 5.2 microg/g wet weight. The usefulness of presenting metals in this way to assess potential bioaccumulators is further considered against other presentation methods.

UCP3 and its putative function: consistencies and controversies

The physiological function of uncoupling protein 3 (UCP3) is as yet unknown. Based on its 57% homology to UCP1 whose physiologic function is uncoupling and thermogenesis, UCP3 was attributed with the function of mitochondrial uncoupling through proton-leak reactions. UCP3 is expressed selectively in muscle, a tissue in which it has been estimated that proton leak accounts for approx. 50% of resting energy metabolism. Genetic linkage, association and variant studies suggest a role for UCP3 in obesity and/or diabetes. Studies of the heterologous expression of UCP3 in yeast provide support for the idea that UCP3 can uncouple mitochondrial oxidative phosphorylation, but the physiological relevance of these results is questionable. In vitro studies of mitochondria from Ucp3(-/-) mice provide support, but there are no changes in resting metabolic rate (RMR) of mice. In vivo studies demonstrate increased ATP synthesis, but estimates of substrate oxidation rate indicate no change. Mice that greatly overexpress Ucp3 in muscle have increased RMR. Inconsistent with the function of uncoupling are the observations that fasting results in increased expression of UCP3, but no change in muscle proton leak. Moreover, fasting decreases energy expenditure in muscle. Expression patterns for Ucp3 and lipid-metabolism genes support a physiological role in fatty acid oxidation. Overall, findings support a role for Ucp3 in fatty acid metabolism that may have implications for obesity and/or Type II diabetes.

Endocytosis is enhanced in Tangier fibroblasts: possible role of ATP-binding cassette protein A1 in endosomal vesicular transport

A human genetic disorder, Tangier disease, has been linked recently to mutations in ATP-binding cassette protein A1 (ABCA1). In addition to its function in apoprotein A-I-mediated lipid removal, ABCA1 was also shown to be a phosphatidylserine (PS) translocase that facilitates PS exofacial flipping. This PS translocation is crucial for the plasma membrane to produce protrusions enabling the engulfment of apoptotic cells. In this report, we show that ABCA1 also plays a role in endocytosis. Receptor-mediated endocytosis, probed by both transferrin and low density lipoprotein, is up-regulated by more than 50% in homozygous Tangier fibroblasts in comparison with controls. Fluid-phase uptake is increased similarly. We also demonstrate that bulk membrane flow, including lipid endocytosis and exocytosis, is accelerated greatly in Tangier cells. Moreover, endocytosis is similarly enhanced in normal fibroblasts when ABCA1 function is inhibited by glyburide, whereas glyburide has no effect on endocytosis in Tangier cells. In addition, we demonstrate a decreased annexin V binding in Tangier fibroblasts as compared with controls, supporting the notion that PS transmembrane distribution is indeed defective in the presence of ABCA1 mutations. Furthermore, adding a PS analog to the exofacial leaflet of the plasma membrane normalizes endocytosis in Tangier cells. Taken together, these data demonstrate that ABCA1 plays an important role in endocytosis. We speculate that this is related to the PS translocase function of ABCA1. A loss of functional ABCA1, as in the case of Tangier cells, enhances membrane inward bending and facilitates endocytosis.

Cerivastatin versus branded pravastatin in the treatment of primary hypercholesterolemia in primary care practice in Canada: a one-year, open-label, randomized, comparative study of efficacy, safety, and cost-effectiveness

BACKGROUND

Potential cost differences between statins are driven primarily by drug costs, differential lowering effects on low-density lipoprotein cholesterol (LDL-C) levels, and adverse drug interactions and reactions.

OBJECTIVE

The purpose of this study was to compare the efficacy, safety, and direct treatment costs of cerivastatin and branded pravastatin in adult patients with primary hypercholesterolemia over a 1-year period.

METHODS

This was a multicenter (48 sites), randomized, open-label, parallel-group, optional dose-titration study conducted in Canada. Patients aged 18 to 75 years with documented primary hypercholesterolemia (mean LDL-C > or = 160 mg/dL [> or = 4.5 mmol/L] and at least 1 fasting triglyceride measurement < or = 400 mg/dL [< or = 4.5 mmol/L]) that did not respond adequately to dietary intervention were enrolled. Patients who were on a diet at study entry were instructed to continue that diet for the duration of the study. Patients not following a diet were also entered into the study provided they had received previous dietary counseling and were unwilling or unable to comply with this dietary advice. Before randomization, treating physicians were required to record a target lipid level for each patient and then instructed to randomize patients to treatment with any dose and any titration schedule of cerivastatin or branded pravastatin according to their normal practice. Physicians were not required to titrate the study drug dose if the patient did not achieve the predefined target goal. Lipid analyses were conducted at baseline/randomization and at months 3, 6, 9, and 12. All samples drawn for lipid analyses were collected after a fast of > or = 10 hours. A cost-minimization approach was used to compare the direct treatment costs between cerivastatin and branded pravastatin. Since the analysis was from the perspective of the third-party payer (Ministries of Health), only costs attributed to the third-party payer were included.

RESULTS

A total of 417 patients were randomized to once-daily treatment with cerivastatin 0.1 mg to 0.4 mg (n = 209) or branded pravastatin 10 mg to 40 mg (n = 208); 39 (9.4%) of patients discontinued prematurely, 19 (4.6%) because of an adverse event. The incidence of adverse events was similar for cerivastatin (73.6%) and branded pravastatin (74.9%). The majority of adverse events were mild or moderate and included headache, nausea, pain, and dizziness. Both cerivastatin and pravastatin were effective in lowering LDL-C to target levels (mean reduction 29.8% and 27.5%, respectively, P = 0.35). An LDL-C decrease of > or = 20% from baseline to end point was achieved in 74.2% of cerivastatin patients and 74.0% of pravastatin patients. The annualized direct hyperlipidemia treatment cost was 19% higher in the branded pravastatin group compared with the cerivastatin group. A sensitivity analysis designed to examine the impact of generic pricing on the cost-minimization analysis indicated that the cost difference between cerivastatin and generic pravastatin was not significant.

CONCLUSIONS

Both cerivastatin and branded pravastatin were well tolerated and effective in lowering LDL-C by > or = 20% versus baseline. A cost savings in favor of cerivastatin was a reflection of the lower drug acquisition cost of cerivastatin compared with branded pravastatin.

Efficacy of atorvastatin in achieving National Cholesterol Education Program low-density lipoprotein targets in women with severe dyslipidemia and cardiovascular disease or risk factors for cardiovascular disease: The Women's Atorvastatin Trial on Cholesterol (WATCH)

BACKGROUND

Recent studies have demonstrated that women at high risk for cardiovascular disease (CVD) benefit from cholesterol lowering to an extent similar to that of men. The ability to achieve established treatment goals for low-density lipoprotein cholesterol (LDL-C) in women with clearly defined risk factors has not been examined in detail.

METHODS AND RESULTS

We have determined the efficacy and frequency of achieving target levels for LDL-C with atorvastatin on the basis of National Cholesterol Education Program Adult Treatment Panel II recommendations in 318 women according to the presence of CVD (198 women) or risk factors for CVD (120 women) and the presence of mixed dyslipidemia with obesity with or without CVD (72 women). Mean baseline LDL-C concentrations for women with established CVD were in the upper 10% of the distribution for age-matched North American women and, for those without CVD, were also extremely elevated and were in the top 5% of the LDL-C distribution for age-matched women in this population. The majority of participants without CVD (63%) reached LDL-C targets (LDL-C <or=160 mg/dL [4.1 mmol/L] if <2 CHD risk factors and LDL-C <or=130 mg/dL [3.4 mmol/L] if >or=2 CVD risk factors) with 10 mg atorvastatin and 79% reached targets with up to 20 mg of atorvastatin. For women with established CVD, 34% achieved an LDL-C <or=100 mg/dL (2.6 mmol/L) with 10 mg and 60% reached this target with up to 20 mg of atorvastatin. With maximal titration to the LDL-C target, up to and including 80 mg atorvastatin, 87% of women without CVD and 80% of women with established CVD achieved LDL-C targets. The presence of mixed dyslipidemia with obesity did not affect the frequency of achieving LDL-C targets.

CONCLUSION

Atorvastatin is very effective in achieving National Cholesterol Education Program Adult Treatment Panel II target concentrations for LDL-C in the majority of women with established CVD or CVD risk factors.

Attachment styles in older European American and African American adults

OBJECTIVES

Differential attachment styles have been linked to differential emotion regulation and ability to cope with stress in samples of young adults. There are few data on attachment styles in older adults despite the fact that attachment relationships are said to play a significant role in psychological well-being throughout the life span. The goal of the study was to examine attachment patterns in older adults.

METHODS

Participants were 800 community-dwelling older European Americans and African Americans (M = 74 years) living in a large urban community. Attachment measures included the family and friend intimacy subscales from the Network Analysis Profile and the Relationship Scales Questionnaire.

RESULTS

In contrast to findings with younger individuals, where the majority of respondents have been found to be secure (i.e., comfortable with closeness and dependency), the majority of the present sample were found to be dismissing/avoidant (i.e., uncomfortable with closeness, compulsively self-reliant). European Americans scored higher than African Americans on attachment security, whereas African Americans scored higher than European Americans on dismissing attachment. However, the assessment of relatedness based on the Network Analysis Profile, where respondents named their closest kin, indicated that African Americans had higher scores than European Americans, though their networks were smaller.

DISCUSSION

Age and ethnicity differences appear to reflect cohort effects related to the impact of economic hardship on families earlier this century and racial prejudice. The high rates of dismissing attachment and low rates of secure attachment in this large urban population suggest that these individuals may be at risk for social isolation and poor health as they become older and more frail.

Lipid screening to prevent coronary artery disease: a quantitative evaluation of evolving guidelines

BACKGROUND

There is strong evidence to support the treatment of abnormal blood lipid levels among people with cardiovascular disease. Primary prevention is problematic because many individuals with lipid abnormalities may never actually develop cardiovascular disease. We evaluated the 1998 Canadian lipid guidelines to determine whether they accurately identify high-risk adults for primary prevention.

METHODS

Using data from the Lipid Research Clinics and receiver operating characteristic (ROC) curves, we compared the diagnostic performance of the 1998 lipid guidelines when risk factors for coronary artery disease (CAD) were counted versus calculating risk using Framingham risk equations. We also compared the diagnostic accuracy of the 1998 guidelines with guidelines previously published by the National Cholesterol Education Program in the United States and the 1988 Canadian Consensus Conference on Cholesterol and then used Canadian Heart Health Survey data to forecast lipid screening and treatment rates for the Canadian population.

RESULTS

The Framingham risk equations were more accurate than counting risk factors for predicting CAD risk (areas under the ROC curves, 0.83 [standard deviation (SD) 0.02] v. 0.77 [SD 0.03], p < 0.05). Risk counting was a particularly poor method for predicting risk for women. The 1998 Canadian guidelines identified high-risk individuals more accurately than the earlier guidelines, but the increased accuracy was largely due to a lower false-positive rate or a higher true-negative rate (i.e., increased test specificity). Using the 1998 lipid guidelines we estimate that 5.9 million Canadians currently free of cardiovascular disease would be eligible for lipid screening and 322,705 (5.5%) would require therapy.

INTERPRETATION

Calculating risk using risk equations is a more accurate method to identify people at high risk for CAD than counting the number of risk factors present, especially for women, and the 1998 Canadian lipid screening guidelines are significantly better at identifying high-risk patients than the 1988 guidelines. Many of our findings were incorporated into the new 2000 guidelines.

High-density lipoprotein cholesterol esterification and transfer rates to lighter density lipoproteins mediated by cholesteryl ester transfer protein in the fasting and postprandial periods are not altered in type 1 diabetes mellitus

Background: Diabetes mellitus is associated with atherosclerosis that has, in part, been ascribed to abnormalities in the reverse cholesterol transport system. Methods: We determined, in the fasting and post-alimentary periods, rates of HDL cholesterol esterification and transfer to apoB-containing lipoproteins, cholesteryl ester transfer protein (CETP) concentration, and apoB lipoprotein size in 10 type 1 diabetics and 10 well-matched controls. Autologous HDL was labeled with [14C]cholesterol and incubated at 37 degrees C during a period of 30 min for measurement of the cholesterol esterification rate (CER), as well as for 24 h for measurement of the endogenous HDL [14C]cholesteryl ester ([14C]CE) transfer rate to apoB-containing lipoproteins after 2- and 4-h incubations with the subject's own plasma. Exogenous cholesteryl ester transfer activity (CETA) was estimated by incubation of the participant's plasma (CETP source) with [14C]CE-HDL and VLDL from a pool of plasma donors. ApoB lipoprotein size was determined using non-denaturing polyacrylamide gradient gel electrophoresis of whole plasma. Results: Contrary to previous studies, we showed that even not well-controlled type 1 diabetics did not differ from lipid-matched, non-diabetic subjects in HDL-[14C]cholesterol esterification rate, transfer rates, or CETP concentration. CETP concentration correlates with the exogenous method of [14C]CE transfer and with the endogenous method only when the latter is corrected for plasma triacylglycerol (TG) concentration. In addition, during the postprandial phase, diabetic patients' VLDL are smaller and IDL size increases less than in controls. Conclusion: In type 1 diabetes mellitus, CETA is not altered when the plasma levels of donor and/or acceptor lipoproteins are within the normal range.

Evaluation of a second set of lateral lasers for easier patient positioning in radiotherapy

On modern linear accelerators patient set-up is often awkward due to the height of the isocentre. A second set of lateral lasers was mounted approximately 20 cm below the isocentre allowing patient positioning at an ergonomical height. A small randomised study involving 16 heavy patients treated for pelvic malignancies demonstrated that using the lower lasers for patient set-up is not only likely to reduce strain on staff but also speed up the set-up process.

Is hormone replacement therapy cardioprotective? Decision-making after the heart and estrogen/progestin replacement study

Coronary artery disease (CAD) is the major cause of death in women. Postmenopausal status is associated with a twofold increase of risk for cardiovascular events, in part because of detrimental changes in plasma lipoproteins and endothelial function. Hormone replacement therapy (HRT) has beneficial effects on plasma lipids, flow-mediated vasodilation and fibrinolysis that could be expected to have positive effects on the incidence of cardiovascular events in many postmenopausal women. However, oral HRT also has procoagulant effects and clearly increases the risk of venous thromboembolism. The prothrombotic effects of oral estrogen are not a major concern for the majority of healthy women and major studies including the Framingham Heart Study and the Nurses' Health Study showed that HRT use is associated with protection from cardiovascular disease. In contrast, the Heart and Estrogen/progestin Replacement Study (HERS) failed to show a beneficial effect of oral HRT on cardiovascular events in older women with advanced CAD. In such women, the acute prothrombotic effects of oral estrogen may outweigh the long-term antiatherosclerotic effects of HRT. Until the results of other randomized controlled studies are complete, advice regarding HRT should be based on anticipated benefits on CAD risk factors versus the overall risk of both venous and arterial thrombosis.

Coronary artery disease and women: applying the guidelines for risk factor management

Coronary artery disease (CAD) is the leading cause of death for women. In large part because of increased age at presentation and a greater frequency of concomitant morbidities, women who develop CAD have a poorer prognosis than do men. Although the long term outcome of revascularization procedures is good, the associated procedural morbidity and mortality in women is high. More emphasis should be placed on the primary and secondary prevention of CAD in women. Although women respond well to risk factor modification, including lipid-lowering therapies, recent data indicate that their awareness of risk factors and prevention strategies is poor. Physician risk factor assessment and adherence to current guideline recommendations are essential in preventing the development or progression of CAD in women.

Diet and waist-to-hip ratio: important predictors of lipoprotein levels in sedentary and active young men with no evidence of cardiovascular disease

OBJECTIVE

Healthy, young men were studied to determine the relationship of energy and nutrient intake and physical activity to concentrations of plasma lipoprotein and cholesteryl ester transfer protein.

DESIGN

A cross-sectional study compared active and sedentary male subjects (17 to 35 years old) with no personal or family history of coronary heart disease. Participants kept 20-day food and activity journals. Individual intakes of energy, protein, carbohydrate, fat, saturated fat, monounsaturated fatty acids, polyunsaturated fatty acids, dietary fiber, and alcohol were evaluated. Measurements of blood lipids (total cholesterol and triglycerides, high- and low-density lipoprotein cholesterol); apolipoproteins; cholesteryl ester transfer protein; anthropometric variables (body mass index, waist-to-hip ratio, percentage of body fat); and aerobic capacity were taken during fall and spring data collection periods. SUBJECT SELECTION: Subjects were selected on the basis of normal blood lipid levels, absence of underlying disease, and willingness to comply with their current level of physical activity for the duration of the study. Minimal sample size for statistical power was 12 men per group: 12 of 15 subjects who exercised and 13 of 15 subjects who were sedentary completed all phases of the study.

STATISTICAL ANALYSES

Statistical analyses consisted of 2-way analysis of variance (activity level and season). Pearson product moment correlations and multiple regression analyses were conducted to assess whether energy and nutrient intakes, physical activity status, and/or anthropometric variables predicted plasma concentrations of lipids and apolipoproteins.

RESULTS

Lower waist-to-hip ratio, and not specifically activity level, was associated with higher levels of high-density lipoprotein cholesterol (HDL-C) and lower levels of low-density lipoprotein cholesterol (LDL-C). Dietary intake of saturated and monounsaturated fats and alcohol predicted changes in some apolipoprotein and lipoprotein levels.

APPLICATIONS

Use of waist-to-hip ratio in the primary prevention of coronary heart disease is a simple and cost-effective measure to predict development of abnormal lipoprotein profiles in young men. Specific dietary recommendations include adoption of a heart-healthy diet with emphasis on monounsaturated fatty acids (10% to 12% of energy or one third of total fat intake) and the suggestion that small amounts of alcohol (< 3 drinks per week) may, indeed, be beneficial. Because alcohol and waist-to-hip ratio were both important predictors of LDL-C level, even in active young men, the consumption of low levels of alcohol may be beneficial only if waist-to-hip ratio is maintained within the healthful range by achieving an appropriate balance of physical activity and macronutrient intake.

Transplantation of cryopreserved osteochondral Dowel allografts for repair of focal articular defects in an ovine model

The purpose of this study was to test whether successful cryopreservation of osteochondral tissue is possible and whether, with the appropriate surgical procedure, it can be used for the successful repair of focal articular defects within joints. Fresh (nonfrozen) and snap-frozen (plunged in liquid nitrogen and thawed in a water bath at 37 degrees C, repeated three times) autografts were used as positive and negative controls, respectively. Snap-frozen, frozen (fresh tissue placed in a freezer at -80 degrees C), and cryopreserved (immersed in 10% dimethyl sulfoxide for 30 minutes and then frozen at 1 degrees C/min to -80 degrees C) allografts were transplanted into the knees of adult sheep. Outcomes were evaluated 3, 6, and 12 months after transplantation. The morphological, histological, biochemical, and biomechanical behaviors and characteristics of the graft cartilage, the host cartilage adjacent to the grafts, and the opposing tibial cartilage were assessed. Freezing protocols that yielded poor chondrocyte recovery after thawing (frozen and snap-frozen) resulted in poor overall graft outcome. The cryopreservation protocol, however, resulted in intermediate recovery (50%) of chondrocytes and in intermediate overall graft outcome compared with fresh autografts. The membrane integrity of the allograft chondrocytes immediately following cryopreservation was identified as the most reliable predictor of long-term outcome of the graft. Further improvements in cryopreservation technique may lead to an effective method of banking osteochondral tissue for successful transplantation for the repair of focal defects and larger joint reconstructions.

Comparative effects of simvastatin and cholestyramine on plasma lipoproteins and CETP in humans

Cholesteryl ester transfer protein (CETP) mediates neutral lipid transport in plasma, resulting in a net transfer of cholesteryl ester from high density lipoprotein to very low density lipoprotein. CETP gene expression is regulated by cholesterol, and plasma CETP level increases in patients with hyperlipidemia and with cholesterol feeding. Simvastatin, unlike cholestyramine, reduces hydroxymethylglutaryl coenzyme A reductase activity and may decrease a cellular pool of cholesterol, which is regulatory for CETP gene expression. The effects of simvastatin and cholestyramine on plasma lipids and CETP in 24 male and 19 female patients with primary hypercholesterolemia were compared. Following a four-week placebo period, patients were randomly assigned to receive either simvastatin or cholestyramine. Medication was increased in a stepwise fashion (from 10 to 40 mg for simvastatin and from 8 to 24 g for cholestyramine) as required at six-week intervals to maintain a low density lipoprotein cholesterol (LDL-C) level below 3.4 mmol/L. At the end of the 18-week study, the mean dose of simvastatin was 28.6 mg/day and of cholestyramine 19.3 g/day. Simvastatin was more effective than cholestyramine in lowering LDL-C (-36.8% versus -27. 2%; P=0.031) and triglycerides (-8.5% versus +12.5%; P=0.045). Plasma CETP level decreased by 14.8% following treatment with simvastatin (P=0.003) but did not change following cholestyramine treatment. This study demonstrates that, compared with cholestyramine, simvastatin results in more favourable improvements in the plasma lipoprotein profile and also lowers plasma levels of CETP.

Characterization of a cholesterol response element (CRE) in the promoter of the cholesteryl ester transfer protein gene: functional role of the transcription factors SREBP-1a, -2, and YY1

Cholesteryl ester transfer protein (CETP) is expressed in human adipocytes, where it acts to promote selective uptake of HDL-CE (Benoist, F., M. McDonnell, P. Lau, R. Milne, and R. McPherson. 1997. J. Biol. Chem. 272: 23572;-23577). In contrast to other major sterol-responsive genes such as 3-hydroxy-3-methylglutaryl coenzyme A reductase CETP expression is up-regulated rather than down-regulated in response to cholesterol. To define elements involved in cholesterol-mediated up-regulation of CETP gene expression, deletion derivatives of the CETP promoter were cloned into a luciferase reporter construct and transfected into the human liposarcoma cell line SW872, cultured in the presence or absence of lipoproteins. A fragment associated with a positive cholesterol response was identified between nucleotides -361 and -138 (relative to the initiation site of transcription) of the promoter. This region contains a tandem repeat of a sequence known to mediate sterol dependent regulation of the hamster HMG-CoA reductase gene. We have putatively denoted this region, the cholesterol response element (CRE). Using gel mobility shift assays we demonstrate that both YY1 and SREBP-1 interact with the CRE of CETP. Furthermore, in transient co-transfection experiments, both YY1 and SREBP-1a were found to trans-activate, in a dose-dependent manner, the luciferase activity of constructs harboring the CRE. We also demonstrate that SREBP-2, is able to trans-activate a luciferase construct harboring the CRE although much less effectively as compared to SREBP-1. Finally, functional analysis of the CRE confirms its regulatory role in modulating CETP gene expression through its interaction with YY1 and SREBP-1a.

Controversies in primary prevention among hyperlipidemic patients

Data from a number of population-based primary prevention trials clearly indicate that reducing total serum cholesterol levels leads to a reduced risk of coronary artery disease and death. Similarly, for patients with coronary artery disease, reducing total serum cholesterol levels proved to be an effective secondary prevention strategy, leading to a reduced risk of coronary events and death. Targeting high risk patients is a particularly important component of primary prevention. The overall benefit of treatment is significantly reduced when cholesterol-lowering strategies are initiated later in life. To assist in both primary and secondary prevention strategies, an outline of guidelines developed by a Health Canada working group for the management of hyperlipidemia have recently been published.