Muscimol inhibits plasma membrane rupture and ninjurin-1 oligomerization during pyroptosis

Pyroptosis is a cell death process that causes inflammation and contributes to numerous diseases. Pyroptosis is mediated by caspase-1 family proteases that cleave the pore-forming protein gasdermin D, causing plasma membrane rupture and release of pathogenic cellular contents. We previously identified muscimol as a small molecule that prevents plasma membrane rupture during pyroptosis via an unidentified mechanism. Here, we show that muscimol has reversible activity to prevent cellular lysis without affecting earlier pyroptotic events. Although muscimol is a well-characterized agonist for neuronal GABAA receptors, muscimol protection is not altered by GABAA receptor antagonists or recapitulated by other GABAA agonists, suggesting that muscimol acts via a novel mechanism. We find that muscimol blocks oligomerization of ninjurin-1, which is required for plasma membrane rupture downstream of gasdermin D pore formation. Our structure-activity relationship studies reveal distinct molecular determinants defining inhibition of pyroptotic lysis compared to GABAA binding. In addition, we demonstrate that muscimol reduces lethality during LPS-induced septic shock. Together, these findings demonstrate that ninjurin-1-mediated plasma membrane rupture can be pharmacologically modulated and pave the way toward identification of therapeutic strategies for pathologic conditions associated with pyroptosis.

Pyroptosis and the cellular consequences of gasdermin pores

The family of gasdermin proteins plays a key role in the host response against external and internal pathogenic signals by mediating the form of inflammatory regulated cell death known as pyroptosis. One of the most well-studied gasdermins within innate immunity is gasdermin D, which is cleaved, oligomerizes, and forms plasma membrane pores. Gasdermin D pores lead to a number of downstream cellular consequences including plasma membrane rupture, or cell lysis. In this review, we describe mechanisms of activation for each of the gasdermins, their cell type specificity and some disease associations. We then discuss downstream consequences of gasdermin pore formation, including cellular mechanisms of membrane repair. Finally, we present some important next steps to better understand pyroptosis and the cellular consequences of gasdermin pore formation.

Impact of oral Phytozen® EQ supplementation on plasma cortisol and behavior responses of young horses exposed to stressful stimuli

Calming supplements are common in the equine industry. This study tested the hypothesis that Phytozen® EQ, a blend of citrus botanical oils, magnesium, and yeast would reduce startle response as well as reduce behavioral and physiological signs of stress in young (1.5-6 years of age) horses (n = 14) when tied in isolation and when trailered in isolation. During the 59-day (d) trial, horses were assigned to either the control (CON; n=7) or treatment (PZEN; n=7) group that received 56 g of Phytozen® EQ daily. Horses underwent a 10 min isolation test on d 30 and a 15 min individual trailering test on day 52 or 55. For both tests, blood samples were obtained pre, immediately after, and 1-hour (h) post for analysis of plasma cortisol concentrations, which were analyzed by repeated measures ANOVA. On d 59, horses underwent a startle test, for which time to travel 3 m and total distance traveled were recorded. These data were analyzed using a T-test. During trailering, PZEN horses tended to have lower overall geometric mean (lower, upper 95% confidence interval) cortisol concentrations than CON (81 [67, 98] vs. 61 [48, 78] ng/mL; P = 0.071). For the startle test, PZEN horses tended to have longer geometric mean times to travel 3 m than CON horses (1.35 [0.39, 4.70] vs. 0.26 [0.07, 0.91 seconds [s], P = 0.064). Other data points were not different between treatments (P > 0.1). It is possible that this dietary supplement could have beneficial calming effects on horses undergoing trailering or in novel situations.

Molecular Mechanisms of Pyroptosis

Pyroptosis is a regulated form of cell death that leads to inflammation and plays a role in many different diseases. Pyroptosis was initially defined by the dependence on caspase-1, a protease which is activated by innate immune signaling complexes called inflammasomes. Caspase-1 cleaves the protein gasdermin D, releasing the N-terminal pore-forming domain, which inserts into the plasma membrane. Recent studies have revealed that other gasdermin family members form plasma membrane pores, leading to lytic cell death, and the definition of pyroptosis was revised to gasdermin-dependent cell death. In this review, we discuss how the use of the term pyroptosis has changed over time, as well as currently understood molecular mechanisms leading to pyroptosis and functional consequences of this form of regulated cell death.

A computational study on the three-dimensional printability of precipitate-strengthened nickel-based superalloys

This paper presents a computational framework to study the differences in process-induced microvoid and precipitate distributions during selective laser melting (SLM) of two nickel-based superalloys representative of low (IN718) and high (CM247LC) volume fraction precipitate-strengthened alloys. Simulations indicate that CM247LC has a higher propensity to form process-induced microvoids than IN718. Particle sintering is predicted to be strongly influenced by the powder size distribution. For deposition thickness of approximately 40 μm, thermal gradients during cooling are predicted to be larger for CM247LC than IN718 and consequently expect the development of larger residual stresses for a high volume fraction γ' alloy. A coupled mean field/finite-element approach has been used to predict the precipitate distributions across a simple rectangular build and during a subsequent hot isostatic pressing (HIP) cycle. Unimodal and multi-modal particle distributions are predicted for IN718 and CM247LC at the end of the SLM, respectively. A higher volume fraction of γ' is predicted for CM247LC at the end of the SLM process. During HIP, simulations indicate a dramatic increase in the γ' volume fraction in CM247LC, which can result in a reduction in stress relaxation and lead to a ductility drop.

Effects of supplemental lysine and methionine with zilpaterol hydrochloride on feedlot performance, carcass merit, and skeletal muscle fiber characteristics in finishing feedlot cattle

Feeding zilpaterol hydrochloride (ZH) with ruminally protected AA was evaluated in a small-pen feeding trial. Crossbred steers ( = 180; initial BW = 366 kg) were blocked by weight and then randomly assigned to treatments (45 pens; 9 pens/treatment). Treatment groups consisted of no ZH and no AA (Cont-), ZH and no AA (Cont+), ZH and a ruminally protected lysine supplement (Lys), ZH and a ruminally protected methionine supplement (Met), and ZH and ruminally protected lysine and methionine (Lys+Met). Zilpaterol hydrochloride (8.3 mg/kg DM) was fed for the last 20 d of the finishing period with a 3-d withdrawal period. Lysine and Met were top dressed daily for the 134-d feeding trial to provide 12 or 4 g·hd·d, respectively, to the small intestine. Carcass characteristics, striploins, and prerigor muscle samples were collected following harvest at a commercial facility. Steaks from each steer were aged for 7, 14, 21, and 28 d, and Warner-Bratzler shear force (WBSF) was determined as an indicator of tenderness. Prerigor muscle samples were used for immunohistological analysis. Cattle treated with Met and Lys+Met had increased final BW ( < 0.3) and ADG ( < 0.05) compared to Cont- and Cont+. Supplementation of Lys, Met, and Lys+Met improved G:F ( < 0.05) compared to Cont- during the ZH feeding period (d 111 to 134) as well as the entire feeding period ( < 0.05). Zilpaterol hydrochloride increased carcass ADG ( < 0.05) when compared to non-ZH-fed steers. Methionine and Lys+Met treatments had heavier HCW ( < 0.02) than that of Cont-. Yield grade was decreased ( < 0.04) for Cont+ steers compared to steers treated with Lys, Lys+Met, and Cont-. Tenderness was reduced ( < 0.05) with ZH regardless of AA supplementation. Lysine, Met, Lys+Met, and Cont+ had less tender steaks ( < 0.05) throughout all aging groups compared to Cont-. Steaks from Lys-treated steers were less tender ( < 0.05) than those of Cont+ during the 7- and 14-d aging periods. Nuclei density was the greatest with Cont- cattle compared to all other treatments suggesting a dilution effect of the nuclei in the larger muscle fibers with ZH feeding. Supplementation of Met in conjunction with ZH feeding increased ADG and HCW although this may lead to decreased tenderness even after aging for 28 d. These findings indicated that steers fed ZH may require additional AA absorbed from the small intestine to maximize performance.

Ex vivo porcine vaginal mucosal model of infection for determining effectiveness and toxicity of antiseptics

AIMS

To develop a semi-high-throughput ex vivo mucosal model for determining efficacy and toxicity of antiseptics.

METHODS AND RESULTS

Explants (5 mm) from freshly excised, porcine vaginal mucosa were infected with methicillin-sensitive Staphylococcus aureus (1 × 10(6)  CFU) at the epithelial surface for 2 h. Haematoxylin and eosin staining revealed healthy uninfected tissue and only minor disruptions in tissue infected with methicillin susceptible Staph. aureus (MSSA), which remained in outer epithelial cell layers. After 2 h infection, 10 μl of chlorhexidine digluconate (CHG, 3%), povidone-iodine (PI, 7·5%), octenidine dihydrochloride (OCT, 0·1%) or polyhexamethylene biguanide (PHMB, 0·1%) was applied. Antiseptics significantly reduced MSSA (1-4 log10  CFU/explants) after 0·25 h to 4 h. CHG, PHMB and OCT exhibited persistence at 24 h. In broth culture, CHG 0·012% and PI 0·625% achieved >6 log10 reductions at 2 h. PI-based formulations were more efficacious than unformulated PI. PI-based formulations exhibited no significant cytotoxicity on explants using an MTT assay.

CONCLUSIONS

All antiseptics tested in the mucosal MSSA infection model reduced MSSA. CHG and PI were more potent in broth culture.

SIGNIFICANCE AND IMPACT OF THE STUDY

We developed a semi-high-throughput mucosal model that can identify compounds or formulations with promising antimicrobial and limited cytotoxic properties.

Interlaboratory reproducibility of a microsatellite-based typing assay for Aspergillus fumigatus through the use of allelic ladders: proof of concept

An interlaboratory study was performed with the aim of investigating the reproducibility of a multiplex microbial microsatellite-based typing assay for Aspergillus fumigatus in different settings using a variety of experimental and analytical conditions and with teams having variable prior microsatellite typing experience. In order to circumvent problems with exchange of sizing data, allelic ladders are introduced as a straightforward and universally applicable concept for standardization of such typing assays. Allelic ladders consist of mixtures of well-characterized reference fragments to act as reference points for the position in an electrophoretic trace of fragments with established repeat numbers. Five laboratories independently analysed six microsatellite markers in 18 samples that were provided either as DNA or as A. fumigatus conidia. Allelic data were reported as repeat numbers and as sizes in nucleotides. Without the use of allelic ladders, size differences of up to 6.7 nucleotides were observed, resulting in interpretation errors of up to two repeat units. Difficulties in interpretation were related to non-specific amplification products (which were resolved with explanation) and bleed-through of the different fluorescent labels. In contrast, after resolution of technical or interpretive problems, standardization of sizing data by using allelic ladders enabled all participants to produce identical typing data. The use of allelic ladders as a routine part of molecular typing using microsatellite markers provides robust results suitable for interlaboratory comparisons and for deposition in a global typing database.

Biochemical and toxicopathic biomarkers assessed in smallmouth bass recovered from a polychlorinated biphenyl-contaminated river

Smallmouth bass (Micropterus dolomieu) were collected to quantify the nature and prevalence of biomarker responses, including biochemical indices, toxicopathic lesions and general health indices, among fish collected from polychlorinated biphenyl (PCB)-contaminated and nearby uncontaminated reaches of the Kalamazoo River, Michigan, USA. Blood and tissue samples (gill, liver, spleen, head kidney, trunk kidney, thyroid and gonads) were collected and preserved at necropsy for biochemical and histological analyses. The body condition factor and liver somatic index were significantly lower in fish collected from the downstream, contaminated site. Plasma vitellogenin was not detected in male fish collected from either site. Liver ethoxyresorufin-O-deethylase activity and liver and spleen superoxide dismutase activity were significantly depressed in fish collected from the downstream site. Significant toxicopathic lesions such as glycogen depletion, enhanced macrophage aggregates, hepatic foci of cellular alteration (i.e. preneoplastic lesions) and neoplasia were also detected in the liver of fish collected from the downstream site. This study indicates that many of the biochemical and histopathological biomarker responses were associated with liver and body tissue PCB concentrations. Taken together, the biomarkers of exposure and effect strongly suggest that fish within the downstream site are adversely affected by PCBs and other chemical stressors.

Studies of human physique and sexual attractiveness: sexual preferences of men and women in China

Men and women at Northwest University (n = 631), Xi'an, China, were asked to rate the attractiveness of male or female figures manipulated to vary somatotype, waist-to-hip ratio (WHR), secondary sexual traits, and other features. In study 1, women rated the average masculine somatotype as most attractive, followed by the mesomorphic (muscular), ectomorphic (slim), and endomorphic (heavily built) somatotypes, in descending order of preference. In study 2, the amount and distribution of masculine trunk (chest and abdominal) hair were altered progressively in a series of front-posed figures. Women rated figures with no or little trunk hair as most attractive. Study 3 assessed the attractiveness of front-posed male figures which varied only in length of their nonerect penis. Numerical ratings for this trait were low, but moderate lengthening of the penis (22% or 33% above average) resulted in a significant increase in scores for attractiveness. In study 4, Chinese men rated the attractiveness of back-posed female images varying in waist-to-hip ratio (WHR from 0.5-1.0). The 0.6 WHR figure was most preferred, followed by 0.7, while figures with higher ratios (0.9 or 1.0) were significantly less attractive. Study 5 rated the attractiveness of female skin color: men expressed a marked preference for images which were lighter in color, as compared to images of average or darker skin colors. These results, the first of their kind reported for a Chinese population, support the view that sexual selection has influenced the evolution of human physique and sexual attractiveness in men and women.

Phenotypic and genotypic identification of enterococci isolated from canals of root-filled teeth with periapical lesions

The objectives of the present study were to identify enterococcal species isolated from the canals of root-filled teeth with periapical lesions using biochemical and molecular techniques, and to investigate the genetic diversity of the isolates. Twenty-two Enterococcus strains, isolated from the canals of root-filled teeth with persisting periapical lesions, were identified to species level using rapid ID 32 STREP galleries and partial 16S rDNA sequencing. To subtype the strains, genomic DNA from the isolates was analyzed by pulsed field gel electrophoresis (PFGE) after digestion with SmaI. Intragenic regions of two genes, ace and salA, were sequenced for further differentiation of the isolates. All strains were identified as Enterococcus faecalis by both commercial kit and partial 16S rDNA sequencing. PFGE with SmaI of 22 isolates demonstrated 18 macrorestriction profiles, whereas 13 distinct genotypes were identified after analysis of the ace and salA composite sequences. Most of the isolates from distinct patients had different PFGE profiles. Moreover, in two cases, different E. faecalis strains were found in different root-filled teeth from the same mouth. E. faecalis was the only enterococcal species isolated from the canals of root-filled teeth with periapical lesions. Genetic heterogeneity was observed among the E. faecalis isolates following PFGE and sequence-based typing method. Furthermore, the genetic diversity within root canal strains was similar to previous reports regarding E. faecalis isolates from different clinical and geographic origins.

What theAspergillusgenomes have told us

The sequencing and annotation of the genomes of the first strains of Aspergillus nidulans, Aspergillus oryzae, and Aspergillus fumigatus will be seen in retrospect as a transformational event in Aspergillus biology. With this event the entire genetic composition of A. nidulans, the sexual experimental model organism of the genus Aspergillus, A. oryzae, the food biotechnology organism which is the product of centuries of cultivation, and A. fumigatus, the most common causative agent of invasive aspergillosis is now revealed to the extent that we are at present able to understand. Each genome exhibits a large set of genes common to the three as well as a much smaller set of genes unique to each. Moreover, these sequences serve as resources providing the major tool to expanding our understanding of the biology of each. Transcription profiling of A. fumigatus at high temperatures and comparative genomic hybridization between A. fumigatus and a closely related Aspergillus species provides microarray based examples of the beginning of functional analysis of the genomes of these organisms going forward from the genome sequence.

Primate mating systems and the evolution of immune response

White blood cell (WBC) and red blood cell (RBC) counts were examined in a sample comprising 762 specimens, representing 25 genera and 38 species of captive non-human primates. Animals suffering from illnesses exhibited higher WBC counts than healthy specimens sampled during routine health checks. Analysis of basal WBC counts in healthy animals confirmed a positive correlation between higher cell counts and occurrences of multiple partner mating. This finding remained statistically significant after use of comparative analysis of independent contrasts (CAIC) to control for possible phylogenetic biases in the dataset. These findings were confirmed when using relative testis size as an independent index of mating system. By contrast, RBC counts were not significantly affected by health or correlated with mating systems. These studies confirm a correlation between WBC counts and primate mating systems, and extend the findings to include a positive correlation between WBC counts and relative testis size. However, the findings do not prove that a causal relationship between these variables exists. Further research is required to establish the evolutionary causation of basal WBC counts in primates.

Interleukin-6 and tumor necrosis factor-alpha are not increased in patients with Type 2 diabetes: evidence that plasma interleukin-6 is related to fat mass and not insulin responsiveness

AIMS/HYPOTHESIS

Our aim was to examine the possible direct relationship of interleukin-6 and TNFalpha with insulin sensitivity in humans.

METHODS

We carried out two series of euglycaemic-hyperinsulinaemic clamp experiments. In the first (CLAMP1), skeletal muscle mRNA expression and plasma concentrations of IL-6 and TNFalpha were examined in patients with Type 2 diabetes ( n=6), subjects matched for age (n=6), and young healthy (n=11) control subjects during a 120-min supra-physiological hyperinsulinaemic (40 mU.m(-2).min(-1)) euglycaemic clamp. In the second series of experiments (CLAMP2), patients with Type 2 diabetes (n=6) and subjects matched for age (n=7) were studied during a 240-min high-physiological hyperinsulinaemic (7 mU.m(-2).min(-1)) euglycaemic clamp, during which arterial and venous (femoral and subclavian) blood samples were measured for IL-6 and TNFalpha flux.

RESULTS

In both experiments the glucose infusion rate in the patients was markedly lower than that in the other groups. In CLAMP1, basal skeletal muscle IL-6 and TNFalpha mRNA were the same in all groups. They were not affected by insulin and they were not related to the glucose infusion rate. In CLAMP2, neither cytokine was released from the arm or leg during insulin stimulation in either group. In both experiments plasma concentrations of these cytokines were similar in the patients and in the control subjects, although in CLAMP1 the young healthy control group had lower (p<0.05) plasma IL-6 concentrations. Using data from all subjects, a strong positive correlation (r=0.85; p<0.00001) was observed between basal plasma IL-6 and BMI. Conversely, a negative relationship (r=-0.345; p<0.05) was found between basal plasma TNFalpha and BMI, although this was not significant when corrected for BMI. When corrected for BMI, no relationship was observed between either basal plasma IL-6 or TNFalpha and GIR.

CONCLUSIONS/INTERPRETATION

These data show that the increased circulating IL-6 concentrations seen in patients with Type 2 diabetes are strongly related to fat mass and not insulin responsiveness, and suggest that neither IL-6 nor TNFalpha are indicative of insulin resistance.

CADRE: the Central Aspergillus Data REpository

CADRE is a public resource for housing and analysing genomic data extracted from species of Aspergillus. It arose to enable maintenance of the complete annotated genomic sequence of Aspergillus fumigatus and to provide tools for searching, analysing and visualizing features of fungal genomes. By implementing CADRE using Ensembl, a framework is in place for storing and comparing several genomes: the resource will thus expand by including other Aspergillus genomes (such as Aspergillus nidulans) as they become available. CADRE is accessible at http://www.cadre. man.ac.uk.

Association of bullying with adolescent health-related quality of life

OBJECTIVE

To examine the relationship between being bullied and health-related quality of life (HR-QOL) in adolescence.

METHODOLOGY

Subjects were a cohort of 805 adolescents with a mean age of 13.6 years (standard deviation 0.2 years). An adolescent questionnaire elicited the frequency of being bullied. HR-QOL was measured using the Child Health Questionnaire - Parent Report Form (CHQ-PF50) and Dartmouth COOP Functional Health Assessment Charts for Adolescents.

RESULTS

Thirty-six per cent of boys and 38 per cent of girls reported being bullied at least weekly. Adolescent psychosocial HR-QOL was inversely related to frequency of being bullied, while physical HR-QOL was not related.

CONCLUSION

Peer bullying is an important determinant of adolescent HR-QOL with a negative impact on psychosocial well-being.

Effect of glycerol-induced hyperhydration on thermoregulation and metabolism during exercise in heat

This study examined the effect of glycerol ingestion on fluid homeostasis, thermoregulation, and metabolism during rest and exercise. Six endurance-trained men ingested either 1 g glycerol in 20 ml H2O x kg(-1) body weight (bw) (GLY) or 20 ml H2O x kg(-1) bw (CON) in a randomized double-blind fashion, 120 min prior to undertaking 90 min of steady state cycle exercise (SS) at 98% of lactate threshold in dry heat (35 degrees C, 30% RH), with ingestion of CHO-electrolyte beverage (6% CHO) at 15-min intervals. A 15-min cycle, where performance was quantified in kJ, followed (PC). Pre-exercise urine volume was lower in GLY than CON (1119 +/- 97 vs. 1503 +/- 146 ml x 120 min(-1); p < .05). Heart rate was lower (p < .05) throughout SS in GLY, while forearm blood flow was higher (17.1 +/- 1.5 vs. 13.7 +/- 3.0 ml x 100 g tissue x min(-1); p < .05) and rectal temperature lower (38.7 +/- 0.1 vs. 39.1 +/- 0.1 degrees C; p < .05) in GLY late in SS. Despite these changes, skin and muscle temperatures and circulating catecholamines were not different between trials. Accordingly, no differences were observed in muscle glycogenolysis, lactate accumulation, adenine nucleotide, and phosphocreatine degradation or inosine 5'-monophosphate accumulation when comparing GLY with CON. Of note, the work performed during PC was 5% greater in GLY (252 +/- 10 vs. 240 +/- 9 kJ; p < .05). These results demonstrate that glycerol, when ingested with a bolus of water 2 hours prior to exercise, results in fluid retention, which is capable of reducing cardiovascular strain and enhancing thermoregulation. Furthermore, this practice increases exercise performance in the heat by mechanisms other than alterations in muscle metabolism.

Source apportionment of exposure to toxic volatile organic compounds using positive matrix factorization

Data from the Total Exposure Assessment Methodology studies, conducted from 1980 to 1987 in New Jersey (NJ) and California (CA), and the 1990 California Indoor Exposure study were analyzed using positive matrix factorization, a receptor-oriented source apportionment model. Personal exposure and outdoor concentrations of 14 and 17 toxic volatile organic compounds (VOCs) were studied from the NJ and CA data, respectively. Analyzing both the personal exposure and outdoor concentrations made it possible to compare toxic VOCs in outdoor air and exposure resulting from personal activities. Regression analyses of the measured concentrations versus the factor scores were performed to determine the relative contribution of each factor to total exposure concentrations. Activity patterns of the NJ and CA participants were examined to determine whether reported exposures to specific sources correspond to higher estimated contributions from the factor identified with that source. For a subset of VOCs, a preliminary analysis to determine irritancy-based contributions of factors to exposures was carried out. Major source types of toxic VOCs in both NJ and CA appear to be aromatic sources resembling automobile exhaust, gasoline vapor, or environmental tobacco smoke for personal exposures, and automobile exhaust or gasoline vapors for outdoor concentrations.

Circulating monocytes are not the source of elevations in plasma IL-6 and TNF-alpha levels after prolonged running

The present study was undertaken to examine the effect of prolonged running on monocyte intracellular cytokine production and plasma cytokine concentration. Blood samples were collected 1 h before, immediately after, 2 h after, and 24 h after a competitive marathon run. There was no change in the number of cells spontaneously producing tumor necrosis factor (TNF)-alpha; however, there was a decrease in the number of cells producing interleukin (IL)-1alpha and IL-6 (P < 0.01) postexercise. In contrast, there was an increase in the number of monocytes that responded to lipopolysaccharide stimulation by producing IL-1alpha, TNF-alpha, and IL-6 (P < 0.01) immediately and 2 h postexercise; however, these cells contained less cytokine (P < 0.05). Plasma IL-6, TNF-alpha, epinephrine, norepinephrine, and cortisol concentrations were markedly increased (P < 0.01) postexercise. These data demonstrate that circulating monocytes are not the source of elevated levels of plasma IL-6 and TNF-alpha after prolonged running. In addition, it is likely that stress hormones result in a decrease in the amount of cytokine produced by LPS-stimulated cells postexercise.

The colonoscope in cecal volvulus: report of three cases

Colonoscopy was employed to attempt detorsion of volvulus of the right colon in four patients considered to be high-risk surgical patients. In one patient detorsion was accomplished, so that emergency laparotomy became unneccesary. The site of torsion was reached in every patient. When detorsion does not occur reasonably soon after the colonoscope enters the right colon, persistent efforts are more likely to be harmful than helpful. Abdominal symptoms in a patient who has been ill or injured for some time should suggest the possibility of volvulus of the right colon. Early diagnosis and earlier employment of colonoscopy would almost surely result in an increased rate of success in accomplishing detorsion. When detorsion is accomplished, subsequent resection of the right colon should be seriously considered as, without it, volvulus is said to recur frequently.

Embryonic expression of the tumor-associated PAX3-FKHR fusion protein interferes with the developmental functions of Pax3

A unique chromosomal translocation involving the genes PAX3 and FKHR is characteristic of most human alveolar rhabdomyosarcomas. The resultant chimeric protein fuses the PAX3 DNA-binding domains to the transactivation domain of FKHR, suggesting that PAX3-FKHR exerts its role in alveolar rhabdomyosarcomas through dysregulation of PAX3-specific target genes. Here, we have produced transgenic mice in which PAX3-FKHR expression was driven by mouse Pax3 promoter/enhancer sequences. Five independent lines expressed PAX3-FKHR in the dorsal neural tube and lateral dermomyotome. Each line exhibited phenotypes that correlated with PAX3-FKHR expression levels and predominantly involved pigmentary disturbances of the abdomen, hindpaws, and tail, with additional neurological related alterations. Phenotypic severity could be increased by reducing Pax3 levels through matings with Pax3-defective Splotch mice, and interference between PAX3 and PAX3-FKHR was apparent in transcription reporter assays. These data suggest that the tumor-associated PAX3-FKHR fusion protein interferes with normal Pax3 developmental functions as a prelude to transformation.

Immediate-release oxybutynin versus tolterodine in detrusor overactivity: a population analysis

We evaluated adherence to treatment with immediate-release (IR) oxybutynin (515 patients) and tolterodine (505 patients) for detrusor overactivity through retrospective analysis of a pharmacy claims database. Outcomes included percentage of patients continuing therapy for 6 months, medication possession ratios, and time to discontinuation of therapy. The proportion of patients continuing therapy for 6 months was statistically superior for tolterodine (32%) compared with IR oxybutynin (22%, p<0.001). Medication possession ratios were also superior for patients in the tolterodine group (medians 0.83 and 0.64, ranges 0.11-1.15 and 0.07-1.13, respectively, p<0.001). Oxybutynin was discontinued significantly earlier (mean 45 days) than tolterodine (mean 59 days, p<0.001) and was switched to another therapy more commonly than tolterodine (19% and 14%, respectively). Tolterodine was favored over oxybutynin for several measurements of patient adherence. However, less than one-third of patients continued therapy with either agent for 6 months. The clinical relevance of these differences is unknown.

Akt promotes cell survival by phosphorylating and inhibiting a Forkhead transcription factor

Survival factors can suppress apoptosis in a transcription-independent manner by activating the serine/ threonine kinase Akt, which then phosphorylates and inactivates components of the apoptotic machinery, including BAD and Caspase 9. In this study, we demonstrate that Akt also regulates the activity of FKHRL1, a member of the Forkhead family of transcription factors. In the presence of survival factors, Akt phosphorylates FKHRL1, leading to FKHRL1's association with 14-3-3 proteins and FKHRL1's retention in the cytoplasm. Survival factor withdrawal leads to FKHRL1 dephosphorylation, nuclear translocation, and target gene activation. Within the nucleus, FKHRL1 triggers apoptosis most likely by inducing the expression of genes that are critical for cell death, such as the Fas ligand gene.

Total hip arthroplasty with insertion of the acetabular component without cement in hips with total congenital dislocation or marked congenital dysplasia

BACKGROUND

End-stage osteoarthritis secondary to total congenital dislocation or severe congenital dysplasia of the hip (class B or C according to the system of Eftekhar or type 2 or 3 according to the system of Hartofilakidis et al.) in adults presents special problems with regard to reconstruction of the hip. The purpose of the present study was to assess the intermediate-term results associated with the use of a porous ingrowth acetabular component for the treatment of these difficult cases.

METHODS

We performed a prospective study of a consecutive series of twenty-one patients (twenty-four hips) who had had a primary total hip arthroplasty with use of a hemispherical acetabular component that was inserted without cement and fixed with screws. No patient was lost to follow-up. Three patients (four hips) died, of causes unrelated to the total hip arthroplasty, before a minimum duration of follow-up of five years. None of these patients had had revision. Of the remaining eighteen patients (twenty hips), fifteen were women and three were men. Ten hips had total dislocation, and ten had severe dysplasia.

RESULTS

After an average duration of follow-up of eighty-three months (range, sixty-four to 102 months), the average Harris hip score was 90 points (range, 68 to 97 points). No patient had revision, loosening, or migration of the acetabular component; pelvic osteolysis; or a continuous radiolucent line at the mesh-bone interface of the acetabular component. The average rate of polyethylene wear was 0.08 millimeter per year (range, zero to 0.21 millimeter per year).

CONCLUSIONS

The porous ingrowth acetabular component that was used in the present study functioned well at the time of the intermediate-term follow-up of this group of patients who had marked congenital dysplasia or total dislocation of the hip. The use of this component decreased the need for structural acetabular grafts. This component appears to perform as well as larger components of this design that have been assessed after similar durations of follow-up.

Optimization of in situ cellular ELISA performed on influenza A virus-infected monolayers for screening of antiviral agents

Viral susceptibility testing has been traditionally performed by the plaque reduction assay (PRA) which is laborious, time consuming, relatively expensive, and requires subjective input by the reader. An in situ cellular enzyme-linked immunosorbent assay (ELISA) has been developed with the potential to overcome many of the limitations of PRA and has been applied to a variety of viruses. This study establishes the specific conditions necessary for susceptibility testing of influenza A virus to antiviral agents such as amount of inoculum size, duration of incubation, fixative type, and cell number; factors which are critical to the performance of the in situ cellular ELISA. In situ cellular ELISA was found to correlate strongly with the plaque assay (PA) (R2 = 0.997, P < 0.002). Both assays were applied to test the susceptibility of influenza A virus to a new antiviral emulsion agent and yielded comparable data. The optimized in situ cellular ELISA can serve as a reliable assay for the rapid screening of large numbers of antiviral agents.

Aspergillus fumigatus catalases: cloning of an Aspergillus nidulans catalase B homologue and evidence for at least three catalases

The presence of catalases in the water soluble fractions of three Aspergillus fumigatus strains was investigated using non-denaturing and denaturing polyacrylamide gel electrophoresis and Western analysis. Using non-denaturing polyacrylamide gel electrophoresis and staining for catalase activity, three separate catalases were identified. An A. fumigatus catalase gene (catB) was cloned from genomic DNA using the Aspergillus niger catR gene as a probe. Polyclonal antibodies were raised to a glutathione S-transferase-CatB fusion product expressed in Escherichia coli. Western analysis indicated that, under denaturing conditions, the polyclonal antibody recognised a 90-kDa band and under non-denaturing conditions, two separate bands were identified. These results indicate that A. fumigatus in addition to CatB, produces at least two other catalases, one of which is similar in size to CatB. The polyclonal antibody was also used to observe catalase expression in mice, experimentally infected with A. fumigatus. Staining was observed heterogeneously throughout the fungal hyphae. This result indicates that catalase is produced by A. fumigatus during invasive aspergillosis.

Substantial carbon recycling from linoleate into products of de novo lipogenesis occurs in rat liver even under conditions of extreme dietary linoleate deficiency

A significant portion of the beta-oxidized carbon skeleton of some polyunsaturated fatty acids can be recycled into de novo lipogenesis, i.e., cholesterol, saturates and monounsaturates. The recycling of carbon from linoleate was quantified in liver lipids of severely linoleate-deficient rats to determine whether it is more likely to be a function of redundancy or could be obligatory. After 13 wk on a control (2 energy % linoleate) or severely linoleate-deficient (<0. 05 energy % linoleate) diet, 7 muCi [1-14C]linoleate was given by gavage and the rats were killed 48 h later. A second linoleate-deficient group received an oral bolus of 256 mg linoleate as a supplement with the radiotracer. In comparison to the controls, 14C recovery in liver total lipids of the linoleate deficient group was increased about 5-fold with increased dpm/g in linoleate (13.7-fold higher), arachidonate (2.7-fold higher) and products of de novo lipogenesis (3.5-fold higher). In livers of control rats, 14C distribution was: 41% arachidonate, 29% linoleate, 22% sterols, 3% oleate, 3% palmitate, and 2% stearate. In livers of linoleate-deficient rats, 14C distribution was: 63% linoleate, 19% arachidonate, 11% sterols, 4% oleate, 3% palmitate, and <1% stearate. Thus, in controls, equivalent amounts of 14C were in products of de novo lipogenesis as in linoleate (29-30%), and in livers of linoleate-deficient rats, a similar proportion of 14C was in products of de novo lipogenesis as was converted to arachidonate (18-19%). We conclude that carbon recycling into de novo lipogenesis accounts for a significant, obligatory component of linoleate metabolism even during extreme linoleate deficiency.

Klebsiella endocarditis: report of two cases and review

The rarity of endocarditis due to Klebsiella species limits its recognition and awareness of its often malignant course. We describe two recent cases of Klebsiella pneumoniae endocarditis and review the clinical context and outcomes of 48 other cases reported in the literature. At our hospital, endocarditis complicated only one of 86 consecutive episodes of bacteremia due to Klebsiella species. In 22 series of endocarditis that we reviewed, Klebsiella species caused < or =1.2% of cases of native valve endocarditis and up to 4.1% of cases of prosthetic valve endocarditis. Valves were replaced in 44% of these cases, and the mortality rate was 49% in cases for which outcome was specified. Valve replacement may be associated with improved survival. We conclude that Klebsiella species are a rare but ominous cause of complicated bacterial endocarditis that requires careful evaluation during the entire course of therapy.

Cloning and characterization of three human forkhead genes that comprise an FKHR-like gene subfamily

Alveolar rhabdomyosarcomas are associated with unique chromosomal translocations t(2;13) and t(1;13), which arise from fusion of the genes for the paired box proteins PAX3 and PAX7, respectively, to the FKHR (forkhead in rhabdomyosarcoma) gene on chromosome 13q14. Here we report the identification and characterization of three novel human forkhead genes with similarity to FKHR. The three genes (HGMW-approved symbols FKHRP1, FKHRL1, and FKHRL1P1) map to chromosomal regions 5q35.2-q35.3, 6q21, and 17p11, respectively. Based on amino acid sequence comparisons of their forkhead domains, FKHRL1, FKHRL1P1, and FKHRP1 share 86, 84, and 68% identity, respectively, with FKHR. While FKHR and FKHRL1 are expressed in every human adult tissue examined, FKHRP1 mRNA expression could not be detected, and FKHRL1P1 expression was present only at low levels. FKHR and FKHRL1 share a similar genomic organization, each having a very large intron 1 (FKHR approximately 130 kb and FKHRL1 > 90 kb), which bisects their respective forkhead domains at identical positions, as well as a second intron just downstream of each stop codon. FKHRP1 and FKHRL1P1 lack introns and contain stop codons that prevent them from yielding full-length proteins. Thus, while FKHR and FKHRL1 represent functional genes, FKHRP1 and FKHRL1P1 probably are processed pseudogenes. These results suggest that these four genes represent an FKHR-like gene subfamily within the larger human forkhead gene family.

Variation in morphotype, karyotype and DNA type of fluconazole resistant Candida albicans from an AIDS patient

Azole-resistant oropharyngeal and oesophageal candidiasis is a recent phenomenon observed in patients with AIDS usually previously treated with fluconazole. Some variation has been observed in antifungal susceptibility testing among separate colonies of Candida albicans from the same patient. This raises the question of whether there are multiple clones present or simply phenotypic variation in expression of azole resistance. To address this question we took 18 isolates grown from multiple swabs taken before and after experimental azole therapy from a single HIV-positive individual with fluconazole-resistant oral candidiasis and compared morphotype, karyotype, PCR-based DNA typing and azole susceptibility. Ten of the isolates were from a single 2-day period. Amongst these 10 there were seven morphotypes, five karyotypes and four polymerase chain reaction (PCR) types. Three further morphotypes, one karyotype and two PCR types were found amongst the eight isolates obtained during the subsequent 4 months. Limited variation in susceptibility to two azoles--fluconazole and D0870--was also seen. This work emphasizes both the large genotype and phenotypic variability of C. albicans isolates in the mouth of AIDS patients with fluconazole resistance, and the difficulties in interpretation of present typing methods.

Nerve-induced disruption and reformation of beta1-integrin aggregates during development of the neuromuscular junction

The earliest biochemical change detected during synaptogenesis is a local elimination of muscle basal lamina proteins. To explore whether this provides signal(s) that regulate postsynaptic differentiation, we examined the effects of innervation on the distribution of beta1-integrins, which were initially present in scattered aggregates complexed with basal lamina ligands. These beta1-integrin aggregates disappear along paths of nerve contact as their basal lamina ligands are eliminated. New accumulations of these proteins then form during assembly of the postsynaptic apparatus. The new beta1-integrin aggregates at developing synapses form partly via a redistribution of mobile molecules on muscle surface. We thus consider whether (a) the removal of integrins' basal lamina ligands alters their cytoplasmic ligand-interactions, causing the dissociation of integrin clusters, and (b) this receptor modulation helps to transduce local changes in pericellular protease activity into cytoplasmic signals that control postsynaptic differentiation.

Itraconazole resistance in Aspergillus fumigatus

Invasive aspergillosis is an increasingly frequent opportunistic infection in immunocompromised patients. Only two agents, amphotericin B and itraconazole, are licensed for therapy. Itraconazole acts through inhibition of a P-450 enzyme undertaking sterol 14alpha demethylation. In vitro resistance in Aspergillus fumigatus to itraconazole correlated with in vivo outcome has not been previously described. For three isolates (AF72, AF90, and AF91) of A. fumigatus from two patients with invasive aspergillosis itraconazole MICs were elevated. A neutropenic murine model was used to establish the validity of the MICs. The isolates were typed by random amplification of polymorphic DNA. Analysis of sterols, inhibition of cell-free sterol biosynthesis from [14C] mevalonate, quantitation of P-450 content, and [3H]itraconazole concentration in mycelial pellets were used to determine the mechanisms of resistance. The MICs for the three resistant isolates were >16 microg/ml. In vitro resistance was confirmed in vivo for all three isolates. Molecular typing showed the isolates from the two patients to be genetically distinct. Compared to the susceptible isolate from patient 1, AF72 had a reduced ergosterol content, greater quantities of sterol intermediates, a similar susceptibility to itraconazole in cell-free ergosterol biosynthesis, and a reduced intracellular [3H]itraconazole concentration. In contrast, AF91 and AF92 had slightly higher ergosterol and lower intermediate sterol concentrations, fivefold increased resistance in cell-free systems to the effect of itraconazole on sterol 14alpha demethylation, and intracellular [3H] itraconazole concentrations found in susceptible isolates. Resistance to itraconazole in A. fumigatus is detectable in vitro and is present in wild-type isolates, and at least two mechanisms of resistance are responsible.

Pure linoleate deficiency in the rat: influence on growth, accumulation of n-6 polyunsaturates, and [1-14C]linoleate oxidation

Essential fatty acid deficiency has been widely studied but the extent to which its effects are attributable specifically to deficiency of linoleate as opposed to deficiency of all unsaturated fatty acids is unknown. Our objective was to evaluate the effect of pure linoleate deficiency on growth as well as changes in the metabolism and oxidation of n-6 polyunsaturates. The diets contained 20 energy % fat blended from 3 energy % pure oleate, 2 energy % linoleate (0.01 energy % in the linoleate-deficient group), 0.3 energy % pure alpha-linolenate, and the balance as palmitate and stearate from fully hydrogenated soybean oil. Thirty-five-day-old rats consumed the two diets for 84 days, after which the linoleate-deficient rats weighed 15% less than the controls (P < 0.05), had mild scaling on the paws, and visible hair loss (in a few rats). Compared with the controls, the ratio of eicosatrienoate to arachidonate after 84 days was elevated in liver (170-fold) and serum (520-fold) phospholipids of the linoleate-deficient group. In total, linoleate-deficient rats consumed 122 mg of linoleate and had a net whole body loss of 479 mg n-6 polyunsaturates compared with an intake of 24,130 mg and a net whole body gain of 7206 mg n-6 polyunsaturates in the control group. Linoleate-deficient rats oxidized 1% of an oral bolus of [1-14C]linoleate over 8 h compared with 34% in the control rats (P < 0.05). We conclude that pure linoleate deficiency has marked effects on accumulation of n-6 polyunsaturates but induces milder gross symptoms, particularly growth retardation, than classical essential fatty acid deficiency. alpha-Linolenate and possibly oleate may have a sparing effect on linoleate oxidation from body stores during linoleate deficiency.

Species differentiation by internally transcribed spacer PCR and HhaI digestion of fluconazole-resistant Candida krusei, Candida inconspicua, and Candida norvegensis strains

PCR amplification of the regions containing the internally transcribed spacers and 5.8S rRNA gene of Candida krusei, C. inconspicua, and C. norvegensis yielded fragments of 510, 460, and 500 bp, respectively. HhaI digestion of these fragments yielded species-specific bands. Random amplification of polymorphic DNA with primer R108 showed interspecific discriminatory band patterns. Susceptibilities to fluconazole and amphotericin B were determined.

The majority of dietary linoleate in growing rats is beta-oxidized or stored in visceral fat

On a quantitative, whole-body basis, little is known about the amount of linoleate that is converted to arachidonate or the partitioning of linoleate and its longer-chain derivatives among lean and fat tissues. The aim of the present study was to examine linoleate balance and organ partitioning in rats consuming a low but adequate level of linoleate. Weanling male Sprague-Dawley rats were given free access to a semipurified diet containing 2.3% of energy as linoleate. Food intake, fecal output and body weight gain were measured for 26 d. Whole-body fatty acid balance analysis showed that 75.5% of the linoleate consumed disappeared (apparently by beta-oxidation), 18.7% was accumulated as linoleate, 3.0% was converted to (n-6) longer-chain polyunsaturated fatty acids, and 1.2% was excreted in the feces Visceral fat contained 64% of the accumulated linoleate, and 23% was in lean tissues. Comparable values for alpha-linolenate were as follows: disappearance (84.9%), accumulation (10.9%), excretion in the feces (2.2%), and conversion to (n-3) longer-chain polyunsaturated fatty acids (1.4%). Visceral fat contained 67% of the accumulated alpha-linolenate, and 23% was in lean tissues. Visceral fat also accumulated 26% of newly synthesized (n-6) longer-chain polyunsaturated fatty acids and 31% of the (n-3) longer-chain polyunsaturated fatty acids. Thus, only 6.5% of dietary linoleate consumed at a low but adequate level for rats appeared in lean tissues as linoleate or its fatty acid metabolites; the rest was beta-oxidized or stored in fat, mostly in visceral fat. These results lead us to speculate whether losses through beta-oxidation contribute to the recommended intake for linoleate in growing rats.

Evaluation of critical body residue QSARs for predicting organic chemical toxicity to aquatic organisms

The critical body residue (CBR) is the concentration of chemical bioaccumulated in an aquatic organism that corresponds to a defined measure of toxicity (e.g., mortality). The CBR can provide an alternative measure of toxicity to traditional waterborne concentration measurements (e.g., concentration in water causing 50% mortality). The CBR has been suggested as a better estimator of dose than the external water concentration and has been postulated to be constant for chemicals with the same mode of action. CBR QSARs have both theoretical and experimental support, developed primarily from studies on the acute toxicity of narcotic chemicals to small fish. CBR QSARs are less well developed for the aquatic toxicity of non-narcotic chemicals. CBRs vary substantially with the mode of action and toxicity endpoint, and may be affected by genetic, hormonal or environmental variation. CBR QSARs may not be applicable to very hydrophobic chemicals, chemicals with specific modes of action, or those with toxicity controlled by kinetic processes such as biotransformation. CBRs models have not been developed or evaluated for sediment and dietary exposure routes. Application of CBR QSARs to contaminated site assessments will require further research and development.

Characterization of the expression and immunogenicity of poliovirus replicons that encode simian immunodeficiency virus SIVmac239 Gag or envelope SU proteins

The effectiveness of the poliovirus vaccines to induce both systemic and mucosal immunity has prompted the development of this virus as a vector in which to express foreign proteins. Our laboratory has previously reported on the construction and characterization of poliovirus genomes that encode HIV-1 proteins (Porter DC, et al.: J Virol 1996;70:2643-2649). To develop this system further, we have constructed poliovirus genomes, referred to as replicons, which encode the SIVmac239 Gag or Env SU in place of the poliovirus capsid gene (P1). Since the replicons do not encode capsid proteins, they are encapsidated into poliovirus by passage with a recombinant vaccinia virus, VVP1, which provides the poliovirus capsid proteins in trans. Using this system, we have derived stocks of the encapsidated replicons which encode the SIVmac239 or Env SU protein. Infection of cells with the replicon that encodes SIVmac239 Gag resulted in the expression of a 55-kDa protein that was released from the infected cells. Analysis of the sedimentation of the released proteins by sucrose density gradient centrifugation revealed that the protein was released from the cell in the form of a virus-like particle. Infection of cells with the replicons encoding the SIVmac239 Env SU resulted in the expression of a 63-kDa protein, corresponding to the molecular mass predicted for the nonglycosylated SIVmac239 SU protein. A second protein with a molecular mass greater than 160 kDa was also immunoprecipitated. After enzymatic deglycosylation, this protein migrated at a molecular mass consistent with that for an Env SU dimer. Analysis of the medium from cells infected with the replicon encoding SIVmac239 Env SU revealed the presence of a protein of molecular mass 85-90 kDa, possibly representing a fragment of the SIVmac239 or Env SU protein. To determine the immunogenicity of the replicons encoding SIVmac239 Gag or Env SU, transgenic mice that express the human receptor for poliovirus, and are thus susceptible to poliovirus, were immunized via the intramuscular route. A serum antibody response to SIV envelope was detected following booster immunization, establishing that the encapsidated replicon was immunogenic. Finally, we demonstrate that the replicons have the capacity to infect peripheral blood mononuclear monocytes/macrophages, suggesting that this cell is a possible target for in vivo infection. The results of our studies, then, lend further support for the development and application of recombinant poliovirus replicons in a vaccine strategy.

Proteolytic disruption of laminin-integrin complexes on muscle cells during synapse formation

To explore whether a neural modulation of muscle integrins' extracellular ligand interactions contributes to synapse induction, we compared the distributions of beta1-integrins and basal lamina proteins on Xenopus myotomal myocytes developing in culture. beta1-Integrins formed numerous organized aggregates scattered over the entire muscle surface, with particularly dense accumulations at specialized sites resembling myotendinous and neuromuscular junctions. Integrin aggregates on muscle cells differed from those on surrounding fibroblasts and epithelial cells, both in their lack of response to cross-linking by multivalent ligands and in their consistent association with the cells' own extracellular matrices. Muscle integrin clusters were usually associated with congruent basal lamina accumulations containing laminin and a heparan sulfate proteoglycan (HSPG), sometimes including fibronectin and vitronectin acquired from the surrounding medium. Immediately prior to synaptic differentiation, any existing laminin and HSPG accumulations along the path of cell contact were eliminated, disrupting otherwise stable laminin-integrin complexes. This apparently proteolytic modulation of integrins' extracellular ligand interactions was soon followed by the accumulation of new congruent accumulations of laminin and HSPG in the developing synaptic basal lamina. Combining these results with earlier findings, we consider the possibility that postsynaptic differentiation is induced, at least in part, by the proteolytic disruption of integrin-ligand complexes at sites of nerve-muscle contact.

Detection of the t(2;13) chromosomal translocation in alveolar rhabdomyosarcoma using the reverse transcriptase-polymerase chain reaction

Rhabdomyosarcoma, a small-, round-cell tumor of skeletal muscle, is the most common soft tissue sarcoma found in children. A specific and unique chromosomal translocation, t(2;13)(q35;q14), has been described cytogenetically in a subset of these tumors and is most often associated with the alveolar histologic subtype. The cloning and sequencing of complementary DNA from fusion transcripts expressed by both cell lines and tumors have shown that this chromosomal translocation results in the fusion of the PAX3 gene on chromosome 2 with a member of the forkhead gene family, FKHR, on chromosome 13. To detect this genetic abnormality we have developed a sensitive method which relies on a reverse transcriptase-polymerase chain reaction with primers designed to be specific for the chromosome 2 and chromosome 13 sides of the translocation. The utility of this approach was tested by analyzing a series of rhabdomyosarcoma cell lines and tumor samples. The data demonstrate that the transcripts derived from the t(2;13) were restricted to tumors having features of the alveolar subtype and that they could be detected with greater ease and sensitivity than with cytogenetic analysis. This approach will facilitate a large-scale group effort to determine the frequency as well as the prognostic and diagnostic significance of this chromosomal rearrangement.

Dioxinlike properties of a trichloroethylene combustion-generated aerosol

Conventional chemical analyses of incineration by-products identify compounds of known toxicity but often fail to indicate the presence of other chemicals that may pose health risks. In a previous report, extracts from soot aerosols formed during incomplete combustion of trichloroethylene (TCE) and pyrolysis of plastics exhibited a dioxinlike response when subjected to a keratinocyte assay. To verify this dioxinlike effect, the complete extract, its polar and nonpolar fractions, some containing primarily halogenated aromatic hydrocarbons, were evaluated for toxicity using an embryo assay, for antiestrogenicity using primary liver cell cultures, and for the ability to transform the aryl hydrocarbon receptor into its DNA binding form using liver cytosol in a gel retardation assay. Each of these assays detect dioxinlike effects. Medaka (Oryzias latipes) embryos and primary liver cell cultures of rainbow trout (Oncorhynchus mykiss) were exposed to concentrations of extract ranging from 0.05 to 45 micrograms/l. Cardiotoxicity with pericardial, yolk sac, and adjacent peritoneal edema occurred after exposure of embryos to concentrations of 7 micrograms/l or greater. These same exposure levels were associated with abnormal embryo development and, at the higher concentrations, death. Some of the fractions were toxic but none was as toxic as the whole extract. In liver cells, total cellular protein and cellular lactate dehydrogenase activity were not altered by in vitro exposure to whole extract (0.05-25 micrograms/l). However, induction of cytochrome P4501A1 protein and ethoxyresorufin O-deethylase activity occurred. In the presence of whole extract, estradiol-dependent vitellogenin synthesis was reduced. Of the fractions, only fraction 1 (nonpolar) showed a similar trend, although vitellogenin synthesis inhibition was not significant. The soot extract and fractions bound to the Ah receptor and showed a significantly positive result in the gel retardation/DNA binding test. Chemical analyses using GC-MS with detection limits for 2,3,7,8-tetrachlorodibenzo-p-dioxin and dibenzofuran in the picomole range did not show presence of these compounds. Our results indicate that other chemicals associated with TCE combustion and not originally targeted for analysis may also pose health risks through dioxinlike mechanisms.

Loss of oncogenic ras expression does not correlate with loss of tumorigenicity in human cells

ras oncogenes are mutated in at variety of human tumors, which suggests that they play an important role in human carcinogenesis. To determine whether continued oncogenic ras expression is necessary to maintain the malignant phenotype, we studied the human fibrosarcoma cell line, HT1080, which contains one mutated and one wild-type N-ras allele. We isolated a variant of this cell line that no longer contained the mutated copy of the N-ras gene. Loss of mutant N-ras resulted in cells that displayed a less transformed phenotype characterized by a flat morphology, decreased growth rate, organized actin stress fibers, and loss of anchorage-independent growth. The transformed phenotype was restored following reintroduction of mutant N-ras. Although loss of the oncogenic N-ras drastically affected in vitro growth parameters, the variant remained tumorigenic in nude mice indicating that mutated N-ras expression is not necessary for maintenance of the tumorigenic phenotype. We confirmed this latter observation in colon carcinoma cell lines that have lost activated K-ras expression via targeted knockout of the mutant K-ras gene.

A Chemical Cue Induces Settlement of Sydney Rock Oysters, Saccostrea commercialis, in the Laboratory and in the Field

The physical and chemical nature of a substratum's surface, including the presence of dissolved compounds or a bacterial film, may induce the settlement of invertebrate larvae. Based on previous observations of (1) enhanced recruitment of Sydney rock oysters (Saccostrea commercialis) on concrete surfaces and (2) high alkalinity at the surface of concrete due to the leaching of calcium hydroxide (Ca(OH)2) from the cement, experiments were designed to test the hypothesis that a surface containing Ca(OH)2 enhances settlement of oysters. The effect of a biofilm on settlement of Sydney rock oysters was also tested. The results obtained from the field experiment differed slightly from those obtained in the laboratory. In both the laboratory and the field, Ca(OH)2 had a positive effect on settlement. No significant effect of a biofilm on settlement on concrete substrata was observed in either experiment; a positive effect of a biofilm on substrata made with sand only or on sandstone was seen in both the laboratory and the field. For the substrata made with Ca(OH)2 and sand, however, the effect of a biofilm was positive in the field but negative in the lab. Although the results from the lab and field experiments were similar, the discrepancy was crucial in accepting or rejecting one of the hypotheses under test. The results of the study demonstrated that (1) the effects of a biofilm on settlement vary with the substratum and (2) these oysters can respond to a chemical cue (Ca(OH)2) in the field. The ecological implications of the ability of larvae to select a habitat in response to chemical cues are discussed.