Feasibility, acceptability and cost efficiency of using webinars to deliver first-line patient education for people with Irritable Bowel Syndrome as part of a dietetic-led gastroenterology service in primary care.

BACKGROUND: Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder. International research suggests dietary intervention as a first-line approach, although dietetic services are struggling to cope with demand. Digital technology may offer a solution to deliver appropriate patient education. The present study aimed to assess the feasibility, acceptability and cost efficiency of using webinars to deliver first-line IBS advice to patients as part of a dietetic-led gastroenterology service in primary care. METHODS: Patients were directed to an IBS First Line Advice webinar on a specialist NHS website. Data were collected from patients pre- and post-webinar use using an online survey. RESULTS: In total, 1171 attendees completed the pre-webinar survey and 443 completed the post-webinar survey. Attendees ranged from under 17 years to over 75 years. Of the attendees, 95% found the webinar easy to access and 91% were satisfied with the content of the webinar. Those with excellent or good knowledge rose from 25% pre-webinar to 67% post-webinar, and confidence in managing their condition improved for 74% of attendees. Using the webinars led to a 44% reduction in referrals for one-to-one appointments with a specialist dietitian in the first year of use. The value of the clinical time saved is estimated at £3593 per annum. The one-off cost of creating the webinar was £3597. CONCLUSIONS: The use of webinars is a feasible, acceptable and cost-efficient way of delivering first-line patient education to people suffering with Irritable Bowel Syndrome as part of a dietetic-led gastroenterology service in primary care.

Pdgf1aa regulates zebrafish neural crest cells migration through Hif-1 in an oxygen-independent manner.

The transcription factor Hif-1α regulates epithelial to mesenchymal transition and neural crest cell chemotaxis in Xenopus. Hif-1α is only stabilised under low oxygen levels, and the in vivo stabilisation of this factor in neural crest cells is poorly understood. Multiple oxygen-independent Hif-1α regulators have been described in cell cultures and cancer models. Among these, the PDGF pathway has been linked to neural crest development. The present study established a connection between the Pdgf pathway and Hif-1α stabilisation in zebrafish. Specifically, embryos with a disrupted Pdgf pathway were rescued by employing hif-1α mRNA through qPCR and immunohistochemistry techniques. The data suggest that oxygen levels in the neural crest are normal and that Pdgf1aa regulates neural crest migration through Hif-1α expression.

The effect of triclosan on posttranslational modification of proteins through citrullination and carbamylation.

OBJECTIVES: The aim of this study was evaluate the effect of triclosan on citrullination and carbamylation, two important protein posttranslational modifications associated with inflammatory conditions such as periodontitis and rheumatoid arthritis. MATERIALS AND METHODS: A range of triclosan concentrations were incubated in the presence of appropriate substrates used for the generation of either citrullinated or carbamylated proteins. The effect of triclosan on protein citrullination and carbamylation in macrophages was also assessed. RESULTS: Citrullination and carbamylation were both significantly decreased by triclosan at concentrations six times lower than the 0.3% triclosan approved by the FDA to use in mouthwash and toothpaste. When macrophages were exposed to triclosan, carbamylation was significantly deceased (p = 0.01), and while citrullination also decreased, this reduction was not statistically significant (p = 0.06). CONCLUSION: Triclosan reduced the generation of protein citrullination and carbamylation in vitro. CLINICAL RELEVANCE: Triclosan may be useful as an adjunct therapy in the management of inflammatory periodontal diseases and help to reduce posttranslational protein modification citrullination and carbamylation) in these tissues.

Azithromycin suppresses P. gingivalis LPS-induced pro-inflammatory cytokine and chemokine production by human gingival fibroblasts in vitro.

OBJECTIVE: Azithromycin is a macrolide antibiotic that appears to have both antibacterial and anti-inflammatory properties. This study aimed to investigate the effect of azithromycin on the production of pro-inflammatory cytokines and chemokines by human gingival fibroblasts (HGF) in vitro. MATERIALS AND METHODS: The effects of azithromycin (0.1 to 10 µg/mL) on the production of interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), and growth-regulated oncogene (GRO) by human gingival fibroblasts cultured in the presence or absence of Porphyromonas gingivalis lipopolysaccharide (LPS) was studied. Cytokine and chemokine protein levels in the culture supernatant were assessed using a Luminex® multiplex immunoassay. RESULTS: P. gingivalis LPS induced cytokine/chemokine (IL-6, IL-8, MCP-1, and GRO) protein production in HGFs, and this effect was suppressed by azithromycin at all concentrations tested. CONCLUSIONS: This study demonstrates that azithromycin suppresses P. gingivalis LPS-induced cytokine/chemokine protein production in HGF, which may explain some of the clinical benefits observed with the adjunctive use of azithromycin in the treatment of periodontitis. CLINICAL RELEVANCE: The current study examines the anti-inflammatory properties of azithromycin which may make it useful as an adjunct treatment to periodontitis. Specifically, we used azithromycin to modulate the production of pro-inflammatory cytokines by gingival fibroblasts known to be important in periodontal inflammation.

Expression of peptidylarginine deiminase-2 and -4, citrullinated proteins and anti-citrullinated protein antibodies in human gingiva.

BACKGROUND AND OBJECTIVE: The presence of citrullinated proteins, and peptidylarginine deiminase types -2 (PAD-2) and -4 (PAD-4) in periodontal tissues, determine the presence of anti-cyclic citrullinated protein antibodies (anti-CCP) in gingival crevicular fluid (GCF) and compare the expression of these proteins between inflamed and non-inflamed sites. MATERIAL AND METHODS: Tissue sections were stained using antibodies against citrullinated proteins, PAD-2 and PAD-4. RT-PCR was performed to investigate PAD-2 and PAD-4 mRNA in inflamed and non-inflamed gingival tissues. Anti-CCP antibodies in gingival crevicular fluid were detected by ELISA. RESULTS: Citrullinated proteins, PAD-2 and PAD-4 were detected in gingiva. There was a correlation between inflammation and expression of these proteins. mRNAs for PAD-2 and PAD-4 were detected in both inflamed and non-inflamed gingival tissues. Antibodies to CCP were found mostly in the GCF of individuals with periodontitis. CONCLUSION: PAD-2 and PAD-4 (protein and mRNA) as well as citrullinated proteins are present in inflamed gingiva, and anti-CCP antibodies can be detected in the GCF of some patients. Tissue expression of citrullinated proteins and PAD increased with the severity of inflammation. The presence of anti-CCP antibodies in GCF was almost exclusive to a subset of patients with periodontitis. Increased expression of these proteins in inflamed gingiva lends support to the notion that periodontal inflammation contributes to the inflammatory burden in a similar way to rheumatoid arthritis.

Distribution of repetitive DNAs and the hybrid origin of the red vizcacha rat (Octodontidae).

Great genome size (GS) variations described in desert-specialist octodontid rodents include diploid species ( Octomys mimax and Octodontomys gliroides ) and putative tetraploid species ( Tympanoctomys barrerae and Pipanacoctomys aureus ). Because of its high DNA content, elevated chromosome number, and gigas effect, the genome of T. barrerae is claimed to have resulted from tetraploidy. Alternatively, the origin of its GS has been attributed to the accumulation of repetitive sequences. To better characterize the extent and origin of these repetitive DNA, self-genomic in situ hybridization (self-GISH), whole-comparative genomic hybridization (W-CGH), and conventional GISH were conducted in mitotic and meiotic chromosomes. Self-GISH on T. barrerae mitotic plates together with comparative self-GISH (using its closest relatives) discriminate a pericentromeric and a telomeric DNA fraction. As most of the repetitive sequences are pericentromeric, it seems that the large GS of T. barrerae is not due to highly repeated sequences accumulated along chromosomes arms. W-CGH using red-labeled P. aureus DNA and green-labeled O. mimax DNA simultaneously on chromosomes of T. barrerae revealed a yellow-orange fluorescence over a repetitive fraction of the karyotype. However, distinctive red-only fluorescent signals were also detected at some centromeres and telomeres, indicating closer homology with the DNA sequences of P. aureus. Conventional GISH using an excess of blocking DNA from either P. aureus or O. mimax labeled only a fraction of the T. barrerae genome, indicating its double genome composition. These data point to a hybrid nature of the T. barrerae karyotype, suggesting a hybridization event in the origin of this species.

Heterogeneity in disease severity in a family with a novel G68V GCK activating mutation causing persistent hyperinsulinaemic hypoglycaemia of infancy.

BACKGROUND/AIM: Glucokinase (GCK)-activating mutations cause persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI). GCK-PHHI patients have regulated insulin secretion and can usually be treated with diazoxide. The six reported cases suggest that the severity of the mutation predicts the clinical phenotype. The aim of this study was to relate genotype to phenotype [clinical phenotype, glucose-stimulated insulin release (GSIR) and GCK functional analysis] in a large pedigree with eight affected individuals. METHODS: The genes encoding B-cell GCK and the K(ATP) channel subunits (ABCC8 and KCNJ11) were sequenced to identify mutations for functional analysis. Genetic variants influencing B-cell function were genotyped in affected individuals. Islet secretory capacity was determined by oral glucose tolerance test RESULTS: A novel GCK mutation (G68V) co-segregating with hypoglycaemia was identified in eight family members. Kinetic analysis revealed that G68V-GCK activity is ~16 times more than wild-type-GCK with an increased affinity for glucose [concentration at half maximal activation (S(0.5)) 1.94 +/- 0.16 vs. 7.43 +/- 0.12, mutant vs. wild type, mean +/- sem]. Mathematical modelling predicted a threshold for GSIR of 1.9 mmol/l in the mutant. Oral glucose tolerance tests showed regulated insulin secretion. The severity of hypoglycaemia and related symptoms in affected subjects were heterogeneous. Clinical presentations were asymptomatic (n = 1), extreme hunger (n = 3), seizures (n = 2) and loss of consciousness (n = 2); 7/8 were managed with diet but the proband was treated with diazoxide and octreotide. Phenotypic modification by a second mutation in the K(ATP) channel genes (ABCC8, KCNJ11) or by common genetic variants in KCNJ11, GCK and TCF7L2 was excluded. CONCLUSION: The novel activating GCK mutation G68V is associated with variable phenotypic severity, supporting modification of GSIR by genetic and/or environmental factors.

Factores socio-familiares asociados al embarazo adolescente en una comunidad rural / Partner-social factors associated to the adolescent pregnancy in a rural community

Introducción: El embarazo en la adolescencia ha sido considerado un problema bio-psicosocial, puesto que implica mayor riesgo de morbilidad materna, menores oportunidades de educación, fortalecimiento del círculo de la pobreza y un mayor riesgo de morbilidad y mortalidad infantil. Objetivo: Analizar las características sociofamiliares en adolescentes embarazadas en una comuna rural de Chile. Material y Método: Estudio retrospectivo, descriptivo y transversal, realizado en la maternidad del Hospital de la Comuna de Bulnes, Chile, año 2004. El grupo estudiado correspondió a 209 adolescentes embarazadas que ingresaron a control prenatal entre los años 2001 al 2003 en consultorios de atención urbano-rural de la comuna de Bulnes. Resultados: El 44,3% de las adolescentes cursó la enseñanza básica, el 25.6% cursó la enseñanza media incompleta, Actualmente el 14% de las adolescentes es soltera con pareja, 39.5% sin pareja, 20.9% casada y el 25.6% convive. El 79.1% proviene de una familia que tiene un ingreso menor a 100 mil pesos (149 Euros), el 20.9% de las adolescentes relata haber sufrido violencia intrafamiliar, el 14% de las madres y el 32.6% de los padres de las adolescentes son fumadores, el 28.5% de las madres y el 58,1% de los padres consume alcohol, siendo alcohólico el 28% de los padres de estas jóvenes. Conclusión: Existe un ambiente sociofamiliar adverso, carente económicamente y con problemas estructurales que llevan a la adolescente a un embarazo precoz

Introduction: The pregnancy in the adolescence has been considered a biopsicosocial problem, since it implies greater risk of maternal morbidity, minors education opportunities, fortification of the circle of the poverty and a greater risk of morbidity and infant mortality. Objective: To analyze the characteristics partner-social in adolescents pregnancied in a rural commune of Chile. Material and Method: Retrospective, descriptive and cross-sectional study, made in the maternity of the Hospital of the Commune of Bulnes, Chile, 2004. The studied group corresponded to 209 pregnant adolescents who entered prenatal-control between 2001 to the 2003 in urban-rural medical attention of the commune of Bulnes. Results: 44.3% of the adolescents attended basic education, the 25,6% attended incomplete hight school. 14% of the adolescents are unmarried, 39,5% without pair and 20,9% married The 79,1% come from a family who has a enter smaller 100 thousand pesos (149 Euros), the 20,9% of the adolescents relates to have undergone intrafamiliar violence. 14% of the mothers and the 32,6% of the parents of the adolescents are smokers, the 28,5% of the mothers and 58.1% of the parents alcohol use, being alcoholic 28% of the parents of these young people. Conclusion: An atmosphere exists to sociofamiliar economically adverse, devoid and with structural problems that take to the adolescent a precocious pregnancy

Regionalization of DNA and protein synthesis in developing stages of the parasitic platyhelminth Echinococcus granulosus.

Echinococcus granulosus is a parasitic platyhelminth, which causes cystid hydatid disease, a major zoonosis involving canids as definitive hosts, and both human and herbivorous domestic animals as intermediate hosts. The disease is caused in intermediate hosts by hydatid cysts, formed upon ingestion of E. granulosus eggs excreted by canids. Protoscoleces, the developmental forms of the parasite infective to canids, are formed in the germinal cellular layer of hydatid cysts. We have found that protoscoleces develop from patches of proliferating cells present in the germinal layer of the hydatid cyst, while most of the other cells of the germinal layer are in a resting state. Further, patches of proliferating cells form buds, which elongate and develop a separate population of cycling cells. In these elongated buds, cell differentiation leads to the main structures of the protoscolex. Protein synthesis is very active among cells of early buds and coincides with their proliferating activity. By contrast, protein synthesis presents a much lower activity in the resting cells of the germinal layer surrounding the growing protoscoleces. In elongated buds at different stages of development, protein synthesis is found mainly close to cellular territories in which cell differentiation occurs. In free infective protoscoleces, cells in DNA synthesis are concentrated in the body of the larva while protein synthesis occurs in the entire larva. This is the first description of the regionalization of DNA and protein synthesis in developing stages of E. granulosus.

A trial of acellular pertussis vaccine in hospital workers during the Cincinnati pertussis epidemic of 1993.

The safety and immunogenicity of acellular pertussis (AP) vaccine in outbreak control was determined in a randomized, double-blind, controlled trial. Participants received AP vaccine (n=102), which contained 25 microg of pertussis toxoid (PT) and 3 microg of filamentous hemagglutinin (FHA), or licensed meningococcal vaccine (MN; n=97). Local reactions (pain or tenderness, redness, swelling, and induration) and systemic reactions (fever, sleepiness or lethargy, and irritability) were similar among AP and MN vaccinees. One month after AP vaccination, the geometric mean level of IgG anti-PT was 33.1 microg/mL, with 2-fold increases in 85% of patients and 4-fold increases in 73% of patients; for IgG anti-FHA, the respective values were 34.7 microg/mL, 92%, and 63%. After 6 months of follow-up, no serological evidence of pertussis was seen among symptomatic or asymptomatic subjects. However, recent evidence of Bordetella pertussis infection before immunization was shown. Thus, AP vaccine was safe and immunogenic in adults.

Poisoning with the recreational drug paramethoxyamphetamine ("death").

OBJECTIVE: To describe the clinical features of paramethoxyamphetamine (PMA; "death") poisoning and to compare these with those of people with self-reported "ecstasy" poisoning. DESIGN: Retrospective casenote review. PARTICIPANTS AND SETTING: 22 patients who presented to the Emergency Department of the Royal Adelaide Hospital (RAH), a major metropolitan teaching hospital, between 1 January 1996 and 31 December 1998 with PMA poisoning identified through urine drug screens; and 61 patients with self-reported ecstasy poisoning between 1 September 1997 and 31 December 1998 found through the hospital databases. RESULTS: Patients with PMA poisoning presented with tachycardia (64%), hyperthermia (temperature > 37.5 degrees C; 36%), coma (41%), seizures (32%), arrhythmias (23%), and QRS intervals > or = 100 ms (50%) with greater frequency and often greater severity than those with self-reported ecstasy poisoning. Two patients with PMA poisoning presented with severe hypoglycaemia (blood glucose level, < 1.5 mmol/L) accompanied by hyperkalaemia (K+ concentration, > 7.5 mmol/L). CONCLUSIONS: At our hospital, PMA poisonings accounted for most of the severe reactions among people who believed they had taken ecstasy. Hypoglycaemia and hyperkalaemia may be specific to PMA poisoning. PMA toxicity should be suspected with severe or atypical reactions to "ecstasy", and confirmed by chromatographic urine drug screens.

The increasing incidence of pertussis in Massachusetts adolescents and adults, 1989-1998.

From 1989 to 1998, the incidence of pertussis increased in Massachusetts adolescents and adults, reaching 71 and 5 per 100,000, respectively, by 1998, whereas the incidence in children remained stable. By 1998, 92% of cases occurred in adolescents and adults. Nationally, in contrast, adolescents and adults had incidences of only 5 and 0.8 per 100,000, respectively, and accounted for 47% of cases. The availability of a specific serologic test and active surveillance by public health personnel in Massachusetts are at least partial explanations. The rise in incidence may be real, however, because, as diagnostic efforts increased, the percentage of patients with a positive serologic test result also increased. Cases identified in adolescents and adults were quite severe: 83% and 87%, respectively, experienced paroxysmal cough, 45% and 41% experienced vomiting, and 41% and 52% experienced a cough lasting >4 weeks. Administration of acellular pertussis vaccine in these age groups could prevent this substantial morbidity.

Evaluation of a guinea pig model to assess interference in the immunogenicity of different components of a combination vaccine comprising diphtheria, tetanus and acellular pertussis (DTaP) vaccine and haemophilus influenzae type b capsular polysaccharide conjugate vaccine.

A guinea pig model to assess the immunogenicity of a combination vaccine containing diphtheria, tetanus and acellular pertussis (DTaP) vaccine and Haemophilus influenzae type b (Hib) capsular polysaccharide conjugated to tetanus toxoid (HibT) was evaluated comparatively with the mouse immunogenicity test to study the effect of combining these antigens on the immunogenicity of various components. The immunogenicity test in mice was performed by subcutaneous injection of groups of 10 animals twice at an interval of four weeks with 1/10 of a single human dose of various formulations of combination vaccines, DTaP or HibT vaccine. The animals were bled at 4 and 6 weeks and IgG or total antibodies to various components were determined by ELISA or RIA. The guinea pig immunogenicity model included groups of animals injected subcutaneously twice at an interval of six weeks with 1.5 times the single human dose of various formulations. The animals were bled at 4, 6 and 8 weeks and serum samples were tested for antibodies to various components by ELISA, RIA and/or neutralization tests. Additionally, potency of tetanus and diphtheria components was assessed as per the US Food and Drug Administration's regulations. Aluminium phosphate (AIPO(4)) adsorbed HibT vaccine or HibT as a combination with AIPO(4)adsorbed DTaP vaccine showed significant increases in IgG antibodies to tetanus toxin in mice as well increased tetanus antitoxin levels in guinea pigs as compared to soluble HibT vaccine. In general, combining DTaP and HibT vaccines did not affect the antibody levels to tetanus and diphtheria toxoids whereas DTaP-HibT combination vaccine elicited significantly lower IgG antibodies to pertussis toxin and filamentous haemagglutinin than DTaP vaccine alone, particularly after first injection. Mice showed similar Hib antibody responses for the combination and HibT alone whereas guinea pigs consistently showed lower anamnestic responses to Hib for combination formulations than for HibT alone. Reducing the amount of HibT and/or tetanus toxoid in the combination formulations reduced this suppression of Hib antibody response in guinea pigs. Suppression of Hib antibody response in combination vaccines has also been reported from recent clinical trials. Based on the results from this study, it appears that the guinea pig model may be able to predict the human response to various components of combination vaccines.

Knowledge-based expert systems for toxicity and metabolism prediction: DEREK, StAR and METEOR.

It has long been recognised that the ability to predict the metabolic fate of a chemical substance and the potential toxicity of either the parent compound or its metabolites are important in novel drug design. The popularity of using computer models as an aid in this area has grown considerably in recent years. LHASA Limited has been developing knowledge-based expert systems for toxicity and metabolism prediction in collaboration with industry and regulatory authorities. These systems, DEREK, StAR and METEOR, use rules to describe the relationship between chemical structure and either toxicity in the case of DEREK and StAR, or metabolic fate in the case of METEOR. The rule refinement process for DEREK often involves assessing the predictions for a novel set of compounds and comparing them to their biological assay results as a measure of the system's performance. For example, 266 non-congeneric chemicals from the National Toxicology Program database have been processed through the DEREK mutagenicity knowledge base and the predictions compared to their Salmonella typhimurium mutagenicity data. Initially, 81 of 114 mutagens (71%) and 117 of 152 non-mutagens (77%) were correctly identified. Following further knowledge base development, the number of correctly identified mutagens has increased to 96 (84%). Further work on improving the predictive capabilities of DEREK, StAR and METEOR is in progress.

A cryoclamp for the rapid cryofixation of the isolated blood-perfused rabbit cardiac papillary muscle preparation at predefined times during the contraction cycle.

There is increasing evidence that the distribution of monovalent cations in cardiac cells may be non-uniform, particularly in the region immediately beneath the sarcolemma, and we have proposed that a build-up of sodium in this region could be an important factor in the development of ischaemia-reperfusion injury. Electron probe X-ray microanalysis is ideal for the study of such changes in distribution but the application of the technique to this problem imposes severe requirements on the specimen and on the method for cryofixation. The specimen must be perfused through its vasculature so that it can be made truly ischaemic and be successfully reperfused. It is necessary to be able to cryofix the specimen without disturbance of its blood supply, electrical stimulation or temperature. It is also important to know the time in the contraction cycle when cryofixation occurs. Here we describe the design of an automated cryofixation device which can be used to cryofix a blood perfused papillary muscle preparation at predetermined time points in the contraction cycle. Preliminary data obtained from the analysis of rabbit papillary muscles subjected to varying periods of ischaemia are included as an example of the use of the cryoclamp.

Tissue-specific changes in angiotensin II receptors in streptozotocin-diabetic rats.

While there have been reports on changes in the renin-angiotensin system and angiotensin II (AT) receptors in diabetes, there is no agreement on the nature of these changes. This study has characterised specific AT receptors in the heart, kidney, liver and adrenal glands of the streptozotocin (STZ)-diabetic rat using radioligand binding studies with the radioligand 125I-[Sar1, Ile8]-angiotensin II. Left ventricular AT receptor density increased by 135% 4 weeks after treatment and by 206% 12 weeks after treatment; in the liver, AT receptor density increased by 476% (4 weeks) and 263% (12 weeks) and in the adrenal gland by 236% (4 weeks) and 109% (12 weeks). In contrast, renal AT receptor density decreased by 49% (4 weeks) and 36% (12 weeks). Competition-displacement assays with losartan, an AT1-selective ligand, showed that the proportion of AT receptor subtypes remained unchanged. STZ treatment decreased plasma angiotensinogen by 72% (4 weeks) and 67% (12 weeks) and increased plasma renin concentration after 12 weeks; plasma renin activity and aldosterone concentrations remained unchanged. Treatment with human insulin (5 U/day) attenuated changes in plasma angiotensinogen and AT receptor density except in the left ventricle. We conclude that there are major changes in AT receptors in the STZ-diabetic rat that are tissue-specific and time-dependent. Plasma angiotensinogen and renin secretion change in directions that result in the maintenance of plasma renin activity and aldosterone concentration.

Toxicity of polyunsaturated fatty acid esters for human monocyte-macrophages: the anomalous behaviour of cholesteryl linolenate.

We have investigated the toxicity to human monocytemacrophages, and susceptibility to oxidation, of different individual dietary fatty acids in cholesterol esters and triglycerides, added to the cell cultures as coacervates with bovine serum albumin. Toxicity was assessed using release of radioactivity from cells preloaded with tritiated adenine. Lipid oxidation was measured by gas chromatography (GC). The triglycerides showed a direct relationship between toxicity and increasing unsaturation, which in turn correlated with increasing susceptibility to oxidation. Triolein (18:1; omega-9) and trilinolein (18:2; omega-6) were non-toxic. Trilinolenin (18:3; omega-3) was toxic only after prolonged incubation. Triarachidonin (20:4; omega-6), trieicosapentaenoin (20:5; omega-3) and tridocosahexaenoin (22:6; omega-3) were profoundly and rapidly toxic. There was a similar relationship between toxicity and increasing unsaturation for most of the cholesterol esters, but cholesteryl linolenate was apparently anomalous, being non-toxic in spite of possessing three double bonds and being extensively oxidised. Probucol and DL-alpha-tocopherol conferred protection against the toxicity of cholesteryl arachidonate and triarachidonin. The oxidation in these experiments was largely independent of the presence of cells. GC indicated that formation of 7-oxysterols might contribute to the toxicity of cholesteryl linoleate. The toxicity of triglycerides suggests that polyunsaturated fatty acid peroxidation products are also toxic. Possible mechanisms of cytotoxicity and relevance to atherosclerosis are discussed.

Prediction of rodent carcinogenicity using the DEREK system for 30 chemicals currently being tested by the National Toxicology Program. The DEREK Collaborative Group.

DEREK is a knowledge-based expert system for the qualitative prediction of toxicity. The DEREK system has been used to predict the carcinogenicity in rodents of the 30 chemicals in the second National Toxicology Program (NTP) carcinogenicity prediction exercise. Seven of the chemicals were predicted to be carcinogens. For 23 chemicals, there was no evidence in the DEREK knowledge base to suggest carcinogenic activity. Supplementary data from a variety of sources have been evaluated by human experts to assess confidence in each DEREK prediction. These sources included standard toxicology reference texts, genotoxicity and subchronic toxicity assay results for each chemical, as well as Salmonella mutagenicity and carcinogenicity data for close structural analogues. This process has led to the proposal of a number of improvements to the DEREK carcinogenicity knowledge base.