EPEN-46. DNA METHYLATION LANDSCAPE OF RECURRENT PEDIATRIC EPENDYMOMA IDENTIFIES KEY DRIVER EVENTS

Pediatric ependymoma has a propensity of developing late and multiple relapses over many years. About 50% of patients will experience relapses and eventually succumb to their disease. Our study is aimed to understand the mechanism of resistance and drivers associated with pediatric ependymoma relapse. We developed 10 sets of patient-derived orthotopic xenograft (PDOX) models of recurrent pediatric ependymoma from both RELA and PFA tumors. Time from primary tumor to last recurrence ranges from 2.75 – 13 years. Number of recurrences per patient ranges from 1 – 7 times. We performed Reduced Representation Bisulfite Sequencing (RRBS) and Whole Genome Bisulfite Sequencing (WGBS) to map the DNA methylation landscape of total of 30 samples of matched primary and recurrent tumors. Molecular subtypes and DNA methylation profiles were maintained, and RELA/PFA signature genes showed similar expression pattern during serial relapses. RELA- and PFA-specific Differentially Methylated CpGs (DMCs) are identified from primary tumors. During the recurrent process, individual patients displayed consistent changes of DMCs and shared DMCs among patients became convergent. We then identified shared common specific DMCs in recurrent RELA and PFA tumors that emerged as the driver signatures. We found that these recurrent DNA methylation signatures could be identified from primary tumors. Our analysis of the PDOX models showed that they can mostly recapitulate humor tumors’ DNA methylation and we were able to identify shared recurrent specific DMCs associated genes in PDOX models. Our comprehensive data is the first of its kind aimed to investigate the epigenetic mechanisms during pediatric ependymoma recurrence.

EXTH-45. THERAPEUTIC EFFICACY OF MUTANT ISOCITRATE DEHYDROGENASE 1 (IDH1) INHIBITOR SYC-435 WITH STANDARD THERAPY IN PATIENT-DERIVED IDH1 MUTANT GLIOMA XENOGRAFT MOUSE MODELS

Mutation in isocitrate dehydrogenase 1 (IDH1) occurs in >70% of WHO grade II/III astrocytomas, oligodendrogliomas and secondary glioblastoma. The mutant enzyme catalyzes the reduction of α-ketoglutaric acid to D-2-hydroxyglutaric acid, leading to cancer initiation. In this study, we examined therapeutic efficacy of SYC-435 (1-hydroxypyridin-2-one), a newly developed mutant IDH1inhibitor, in IDH1 mutant gliomas. IDH1 R132H mutation (homozygous) was detected in BT142 anaplastic oligoastrocytoma (AOA) and R132C mutation (mutant allele frequency 39–50%) in V0914AOA by pyrosequencing. Suppression of cell growth by SYC-435 was observed with more sensitive of mutant over wild-type IDH1. Patient-derived orthotopic xenograft mouse models of BT142AOA and V0914AOA were treated with vehicle, SYC-435 (15 mg/kg/day x 28 days), temozolomide (50 mg/kg/day x 5 days)/fractionated radiation (2 Gy/day x 5 days) (standard therapy), and SYC-435/standard therapy starting 2 weeks after intracranial tumor implantation. Log rank analysis showed SYC-435 alone did not alter survival times. Although standard therapy significantly prolonged survival times in both models (P< 0.0005), SYC-435/standard therapy further extended survival times (P< 0.05) in V0914AOA and exhibited similar trend in BT142AOA. Elevation of 2-HG/α-KG ratio and methylation of H3K4/H3K9 in V0914AOA tumor compared to wild-type model was detected at the end of treatments. SYC-435 with/without standard therapy tended to reduce 2-HG/α-KG ratio and dramatically reduced methylation of H3K4/H3K9. RNA-seq analysis showed sirtuin signaling pathway, mitochondrial dysfunction and oxidative phosphorylation pathways with mitochondrial DNA (mtDNA) encoded molecules were highly affected by all treatments. However, mtDNA regulation did not correlate to survival benefits. In conclusion, SYC-435 possesses anti-tumor effects that are more sensitive in IDH1 mutant gliomas and generated strong synergistic activities with standard therapies for survival benefits with reduced methylation of H3K4/H3K9. Treatments significantly affected mtDNA but significance to survival benefits remains to be elucidated. Our data support the clinical testing of SYC-435 in patients with IDH1 mutant glioma.

PDTM-17. MiR-126, miR-369-5p AND miR-487b DRIVE PEDIATRIC GLIOBLASTOMA INVASION VIA KCNA1

Diffuse invasion is one of the key features that make GBM particularly difficult to treat. We hypothesize that direct comparison of matched invasive (GBMINV) and tumor core GBM cells (GBMTC) would facilitate the discovery of drivers of pediatric GBM (pGBM) invasion. However, GBMINV cells are extremely difficult to obtain from normal brain tissues because aggressive surgical resection of normal tissue carries the risk of serious neurological deficits. Most past and current studies on GBM invasion were and are forced to utilize the resected primary tumor masses. To overcome this barrier, we utilized a panel of 6 pediatric patient tumor-derived orthotopic xenograft (PDOX) mouse models to isolate matching pairs of GBMTC cells and GBMINV cells and confirmed a significantly elevated invasive capacity in GBMINV cells both in vitro and in vivo. Global profiling of 768 human microRNA using a real-time PCR-based Taqman system identified 23 microRNAs were upregulated in the GBMINV cells in at least 4 of the 6 pGBM models as compared with the matching GBMTC cells. We subsequently showed that silencing the top three miRNAINV, miR-126, miR-369-5p, and miR-487b, suppressed tumor cell migration in vitro (both as neurospheres and monolayer cultures) without affecting cell proliferation, and blocked pGBM invasion in mouse brains. Integrated analysis of the mRNA profiling of the same set of GBMTC and GBMINV cells revealed the affected signaling pathways and identified KCNA1 as the sole common computational target gene of the three miRNAINV. Treatment of three pairs of GBMTC and GBMINV cells with two KCNA1 inhibitors, ADWX1 and Agitoxin 2, caused significant suppression of pGBM cell migration in vitro. In conclusion, this study revealed an intrinsically elevated invasive phenotype in GBMINV cells, identified miR-126, -369-5p, and -487b as novel drivers of pGBM invasion, and characterized KCNA1 as a potential therapeutic target for arresting pGBM invasion.

OBSERVATIONS ON THE TRANSPORT OF CARBON DIOXIDE IN THE BLOOD OF SOME MARINE INVERTEBRATES

Although the results we have recorded merely serve to indicate the possibilities of this interesting field of investigation, we have sufficient data to enable us to draw certain general conclusions. In the first place it is evident that the bloods of the more highly developed marine invertebrates, such as the active Crustacia and the Cephalopods, are specially adapted for the carriage of carbon dioxide. The quantity of carbon dioxide taken up by the blood of Maia, Palinurus, or Octopus at any given tension of the gas is, in general, about twice or three times as great as that which is taken up by sea water under the same conditions. On the other hand, the blood of a slow, creeping form, such as Aplysia, or of a sessile animal such as the ascidian Phallusia shows no more adaptation for the carriage of carbon dioxide than does sea water. But our estimations of the CO(2) content of the blood as it circulates in the bodies of these more active invertebrates show that the conditions of transport of this gas differ considerably in some respects from those which obtain in mammals. For the invertebrate blood in the body contains only a relatively small quantity of carbon dioxide, averaging in the forms we examined from 3 to 10 cc. per 100 cc. of blood. This forms a marked contrast with the condition found in mammals where even the arterial blood contains about 50 cc. of CO(2) per 100 cc. of blood. The invertebrate, therefore, works at a very low CO(2) tension. There is a twofold significance in this circumstance. In the first place, it means that only the first portion of the carbon dioxide dissociation curve is in use in the respiratory mechanism. Now an inspection of our curves will show that at these low carbon dioxide tensions the dissociation curves tend to be steeper than at higher tensions. As we intend to show in a later paper it can be proved mathematically that, other things being equal, a blood with a carbon dissociation curve of moderate steepness, i.e. one in which the carbon dioxide content of the blood increases fairly rapidly with increase of carbon dioxide tension, is a more efficient carrier of the gas from the tissues to a respiratory surface than a blood in which the dissociation curve is either steeper or flatter. It would seem as if the active invertebrates avoid the use of too flat a part of their CO(2) dissociation curves by working over the initial steeper portion. Furthermore, it is seen that over the range of this initial steep portion of the curves the changes of reaction produced by the uptake of carbon dioxide are much smaller than at higher tensions of the gas; for these initial portions of the curves are more nearly parallel to the lines of constant reaction calculated for a temperature of 15 degrees C. according to Hasselbalch's method (10) on the assumption that the whole of the combined CO(2) is in the form of sodium bicarbonate. It is evident also that on this assumption the hydrogen ion concentration of the blood of invertebrates (with the exception of the tunicates) would appear to be practically the same as that of the warm-blooded vertebrates-a conclusion confirmed by the direct measurements of Quagliariello (9). On the other hand, our measurements do not lend support to the idea put forward by Collip (4) that in order to maintain an appropriate faintly alkaline reaction an invertebrate needs to retain carbon dioxide in its blood at a comparatively high tension. This idea was based on the observation that at comparatively high CO(2) tensions the blood of invertebrates contains considerably more sodium bicarbonate than does sea water. But our curves show that this is no longer true at the lower values of carbon dioxide tension, the amount of sodium bicarbonate falling off more rapidly in the blood than in the sea water with diminution of the carbon dioxide tension so that in order to maintain an appropriate reaction in the blood only a comparatively small tension of CO(2) is required. The largest amount of carbon dioxide that we found present in the circulating blood of any of the types examined was 9.7 cc. per 100 cc. of blood in the case of Maia, and in most cases the amount was considerably less. But even this lowest value corresponds to a tension of CO(2) of only about 3 mm., so that the tension gradient across the gill membrane must be even less than this. We would emphasize rather the circumstances that as the portion of the dissociation curve over which the reaction is approximately constant is of but small extent, it is necessary that in an active form like Octopus the carbon dioxide produced should be removed rapidly lest an accumulation of it should cause the limits of normal reaction to be exceeded; and this need is correlated with the extreme efficiency of the respiratory apparatus in this animal. It is interesting to notice that the mammal which, in order to obtain an appropriate reaction in the blood, has to work at relatively high carbon dioxide tensions where the dissociation curve is comparatively flat, secures a steeper physiological CO(2) dissociation curve in the body, and with it a more efficient carriage of carbon dioxide and a more constant reaction in the circulating fluid, in virtue of the effect of oxygenation on the carbon dioxide-combining power of its blood (3, 6). Returning now to the consideration of the actual form of the dissociation curves we have obtained-it is a significant fact that it is in those forms such as Maia, Palinurus, and Octopus whose bloods are rich in proteins-particularly hemocyanine-that the initial steep portion of the curve is observed. This suggests that in these forms the blood proteins act as weak acids and expel carbon dioxide from the blood at the low tensions which include the physiological range, just as in vertebrates the hemoglobin similarly displaces carbonic acid from its combination with alkali metal. On the other hand the coelomic fluid of Aplysia contains no pigment and only 0.00672 per cent of protein nitrogen (Bottazzi (11)) and shows no initial rapidly ascending portion of the CO(2) dissociation curve. This is supported by the observation of Quagliariello (9) that the acid-neutralising power of the blood of an invertebrate is roughly proportional to its protein content. It seems as if the proteins of invertebrate blood like the blood proteins of vertebrates, exist in the form of sodium salts which are capable of giving up sodium for the transport of carbon dioxide as sodium bicarbonate. That this is so in the case of hemocyanine follows from the fact that the isoelectric point of this pigment occurs at a hydrogen ion concentration of 2.12 x 10(-5)N, i.e. at a pH of 4.67 (Quagliariello (12)) so that in the alkaline blood of the invertebrates possessing it, hemocyanine will act as a weak acid. It is probable that the initial steep portion of the carbon dioxide dissociation curves which we have found to be of such importance in the respiration physiology of Octopus, Palinurus, and Maia is produced by the competition of this acid with carbonic acid for the available sodium of the blood.

Safe introduction of the VNUS Closure procedure: a multidisciplinary approach

Objectives: The National Institute for Health and Clinical Excellence supports the use of radiofrequency ablation (VNUS Closure) of the long saphenous vein (LSV) as an alternative to stripping. An increase in interest in the procedure is anticipated. The technique can produce serious complications not commonly associated with conventional surgery, and safety is a major concern with its introduction. The aim was to introduce the new technique into a district hospital, without major complications or failures.

Methods: A multidisciplinary team was developed consisting of consultant surgeon, vascular technologist and theatre nurse, who received intensive training and mentoring from a group with considerable experience. All members attended operating theatre and duplex imaging sessions over a period of six months. Approval for the introduction of the technique into our institution was sought from the Medical Director and Clinical Governance Directorate. The results of VNUS Closure surgery were included in the monthly clinical governance and audit meetings. During the consent process, the first patient was informed that the team had not yet undertaken the procedure, but had taken all necessary measures to ensure its competence. Subsequently, patients were advised of our experience and the results.

Results: Of the 18 patients who consented for the study, 13 (72%) were found on duplex scanning to have saphenofemoral reflux suitable for VNUS Closure. VNUS Closure was attempted in 22 LSVs in 13 patients; 21 LSVs (95%) in 12 patients were closed at surgery and 19 (86%) remained completely closed at a median of 12 months (range 3–24 months). There were no deaths and no major complications.

Conclusion: The safe introduction of VNUS Closure in a district hospital can be accomplished through intensive training and a process of mentoring from experienced practitioners, a multidisciplinary approach with a vascular technologist in theatre and attention to governance issues, in particular audit and consent.

Adductor-related groin pain in athletes: correlation of MR imaging with clinical findings

OBJECTIVE

To evaluate gadolinium-enhanced MR imaging in athletes with chronic groin pain and correlate with the clinical features.

DESIGN AND PATIENTS

MR examinations performed in 52 athletes (51 male, 1 female; median age 26 years) with chronic groin pain and 6 asymptomatic control athletes (6 male; median age 29 years) were independently reviewed by two radiologists masked to the clinical details. Symptom duration (median 6 months) and clinical side of severity were recorded. Anatomical areas in the pelvis were scored for abnormality (as normal, mildly abnormal or abnormal) and an overall assessment for side distribution of abnormality was recorded, initially without post-gadolinium sequences and then, 3 weeks later (median 29 days), the post-gadolinium sequences only. Correlation between radiological and clinical abnormality was calculated by Spearman's correlation.

RESULTS

Abnormal anterior pubis and enthesis enhancement significantly correlated with clinical side for both radiologists (both P=0.008). Abnormal anterior pubis and adductor longus enthesis oedema was significant for one radiologist ( P=0.009). All other features showed no significant correlation ( P>0.05). In the control cases there was no soft tissue abnormality but symphyseal irregularity was present ( n=2). For both radiologists assessment of imaging side severity significantly correlated with clinical side for post-gadolinium ( P=0.048 and P=0.023) but not non-gadolinium sequences ( P>0.05).

CONCLUSION

The extent and side of anterior pubis and adductor longus enthesis abnormality on MR imaging significantly and reproducibly correlates with the athletes' current symptoms in chronic adductor-related groin pain.

Failed primary management of iatrogenic biliary injury: incidence and significance of concomitant hepatic arterial disruption

BACKGROUND

Vasculobiliary injury (VBI) is a well-recognized complication of laparoscopic cholecystectomy (LC). In patients with failed primary management of bile duct injury (BDI), an assessment of the hepatic arterial system may be important to determine the presence of VBI. This study was conducted to determine the incidence of VBI in patients with failed primary management of LC-related BDI and to establish a potential correlation between the level of BDI and the incidence of VBI.

METHODS

A retrospective review was conducted on 18 patients referred for failed primary management of LC-related BDI who underwent prospective arteriography as part of the preoperative work-up.

RESULTS

Of the 18 patients who sustained BDI, Bismuth level 4 lesions were found in 7 patients (39%), level 3 in 8 patients (44%), and level 2 in 3 patients (17%). VBI was identified on arteriography in 11 patients (61%). VBI was present in 71% of patients with level 4 lesions, 63% of patients with level 3 lesions, and 33% of patients with level 2 lesions. The time interval from primary management to its failure was longer in VBI than in BDI alone.

CONCLUSIONS

We have observed a high incidence of VBI in patients with failed primary management of LC-related BDI. Arterial disruption may affect the outcome of primary management of BDI.

Cervical cytology smears in sexually transmitted infection clinics in the United Kingdom

OBJECTIVES

To determine the current practice of smear taking in sexually transmitted infection (STI) clinics within the United Kingdom; what proportion of smears are taken within the national guidelines; whether clinics are screening women not covered by the national screening programme. To compare the abnormality rates of routine and opportunistic (that is, in addition to the screening recommendations) smears; the abnormality rates of smears taken within STI clinics with those taken within the community setting.

METHODS

A questionnaire was circulated to all clinics in May 1998. Details of screening practice were requested. The clinics then prospectively collected details of patient's age, GP registration, date and result of previous smear, and current result of all smears taken between 11 May 1998 and 25 May 1998.

RESULTS

There were 1828 smears taken in the 2 week period; 504 (27.6%) were opportunistic. Opportunistic smears had marginal significantly increased rates of low grade abnormalities but lower (but not statistically significant) high grade abnormalities than in routine smears. 231 (12.6%) of the women were not registered with a GP so would not be included in the national programme. The national rates of abnormalities were significantly higher in the STI clinics compared with the community setting.

CONCLUSION

The majority of smears taken within STI clinics fall within the national guidelines, and 12.6% of the women would probably not otherwise have been screened. The rates of abnormality were significantly higher in the STI clinics but smears taken opportunisticly were less likely to have high grade abnormalities. There is no evidence from this study to support the practice of additional smears in the presence of an effective national cytology screening programme.

WIN 17317-3, a new high-affinity probe for voltage-gated sodium channels

The iminodihydroquinoline WIN 17317-3 was previously shown to inhibit selectively the voltage-gated potassium channels, K(v)1.3 and K(v)1.4 [Hill, R. J., et al. (1995) Mol. Pharmacol. 48, 98-104; Nguyen, A., et al. (1996) Mol. Pharmacol. 50, 1672-1679]. Since these channels are found in brain, radiolabeled WIN 17317-3 was synthesized to probe neuronal K(v)1 channels. In rat brain synaptic membranes, [(3)H]WIN 17317-3 binds reversibly and saturably to a single class of high-affinity sites (K(d) 2.2 +/- 0.3 nM; B(max) 5.4 +/- 0.2 pmol/mg of protein). However, the interaction of [(3)H]WIN 17317-3 with brain membranes is not sensitive to any of several well-characterized potassium channel ligands. Rather, binding is modulated by numerous structurally unrelated sodium channel effectors (e.g., channel toxins, local anesthetics, antiarrhythmics, and cardiotonics). The potency and rank order of effectiveness of these agents in affecting [(3)H]WIN 17317-3 binding is consistent with their known abilities to modify sodium channel activity. Autoradiograms of rat brain sections indicate that the distribution of [(3)H]WIN 17317-3 binding sites is in excellent agreement with that of sodium channels. Furthermore, WIN 17317-3 inhibits sodium currents in CHO cells stably transfected with the rat brain IIA sodium channel with high affinity (K(i) 9 nM), as well as agonist-stimulated (22)Na uptake in this cell line. WIN 17317-3 interacts similarly with skeletal muscle sodium channels but is a weaker inhibitor of the cardiac sodium channel. Together, these results demonstrate that WIN 17317-3 is a new, high-affinity, subtype-selective ligand for sodium channels and is a potent blocker of brain IIA sodium channels.

Intra-articular primatised anti-CD4: efficacy in resistant rheumatoid knees. A study of combined arthroscopy, magnetic resonance imaging, and histology

OBJECTIVES

CD4+ T cells sustain the chronic synovial inflammatory response in rheumatoid arthritis (RA). SB-210396/CE 9.1 is an anti-CD4 monoclonal antibody that has documented efficacy in RA when given intravenously. This study aimed to establish the safety and efficacy of the intra-articular administration of SB-210396/CE 9.1 compared with placebo, examining its mode of action using a combined imaging approach of arthroscopy, magnetic resonance imaging (MRI), and histology.

METHODS

Thirteen RA patients with active, resistant knee synovitis, were randomised to intra-articular injection of placebo (n=3), 0.4 mg (n=3) or 40 mg (n=7) of anti-CD4 after sequential dynamic gadolinium enhanced MRI, followed by same day arthroscopy and synovial membrane biopsy. Imaging and arthroscopic synovial membrane sampling were repeated at six weeks. This study used a unique region of interest (ROI) analysis mapping the MRI area analysed to the specific biopsy site identified arthroscopically, thus providing data for all three modalities at the same synovial membrane site.

RESULTS

12 patients completed the study (one placebo treated patient refused further MRI). Arthroscopic improvement was observed in 0 of 2 placebo patients but in 10 of 10 patients receiving active drug (>20% in 6 of 10). Improvement in MRI was consistently observed in all patients of the 40 mg group but not in the other two groups. A reduction in SM CD4+ score was noted in the 40 mg group and in the 0.4 mg group. Strong correlations both before and after treatment, were identified between the three imaging modalities. Intra-articular delivery of SB-210396/CE 9.1 was well tolerated.

CONCLUSIONS

SB-210396/CE 9.1 is safe when administered by intra-articular injection. A trend toward efficacy was found by coordinated MRI, arthroscopic, and histological imaging, not seen in the placebo group. The value of ROI analysis was demonstrated.

Patient education in psoriatic arthritis: a cross sectional study on knowledge by a validated self-administered questionnaire

OBJECTIVE

To assess the level of knowledge in a group of patients with psoriatic arthritis (PsA) following one reading of an information leaflet [UK Arthritis Rheumatism Council (ARC) booklet] using a validated self-administered questionnaire. Comparisons with subsets of the disease and level of general education were also made.

METHODS

A multiple choice self-administered questionnaire was carried out in a group of 59 patients (32 male, 27 female, mean age 47.53 +/- 12.71 yrs) with established disease (mean duration 9.6 +/- 8.5 yrs). The questionnaire covered 4 broad areas of the disease (general knowledge of skin and joint disease, etiology, symptoms, blood test; general management and drug therapy; physiotherapy treatments; joint protection and priorities) and it was written collecting the majority of the information from an ARC booklet on PsA and from advice from the rheumatology team. Detailed statistical analysis was performed to validate the questionnaire and to measure any associations with demographic data.

RESULTS

The questionnaire was consistent, reliable, and easy to read. Patients showed a lack of knowledge with some erroneous beliefs about their disease (i.e., causes, blood tests, longterm drugs). No statistical associations were found between the level of knowledge achieved and demographic data and patterns of disease. A significant association was found between the median score and level of general education (Kruskal-Wallis analysis of variance 7.97, p = 0.02).

CONCLUSION

The questionnaire is a good instrument to assess knowledge in PsA. The ARC booklet alone seems inadequate to provide sufficient knowledge of disease. Patients' erroneous beliefs were highlighted and these should be addressed.

Short-term administration of tall oil phytosterols improves plasma lipid profiles in subjects with different cholesterol levels

To assess the short-term cholesterol-lowering potential of sitostanol-containing tall oil plant sterols, 22 subjects consumed fixed-food diets over two 10-day periods with or without 21.2 mg/kg body weight/d tall oil phytosterols (sitosterol 62%, sitostanol 21%, campesterol 16%, and campestanol 1%) in a randomized crossover study design. On day 10 of each diet, plasma lipoprotein cholesterol levels, plasma phytosterol concentrations, and cholesterol biosynthesis rates were determined. Total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol levels were lower (P < .01) after administration of tall oil phytosterol (4.7 +/- 0.3 and 3.0 +/- 0.3 mmol/L, respectively) versus placebo (5.0 +/- 0.3 and 3.2 +/- 0.3 mmol/L, respectively). Tall oil treatment had no effect on the plasma high-density lipoprotein (HDL) cholesterol level (1.1 +/- 0.1 mmol/L) versus placebo (1.1 +/- 0.1 mmol/L). Similarly, plasma triglyceride (TG) levels did not differ between tall oil (1.3 +/- 0.2 mmol/L) and placebo (1.4 +/- 0.2 mmol/L) treatments. Plasma campesterol (15.8 +/- 3.7 mmol/mol cholesterol) and sitosterol (6.0 +/- 2.1 mmol/mol cholesterol) levels were not different after tall oil treatment versus placebo treatment (15.4 +/- 2.3 and 6.4 +/- 2.0 mmol/mol cholesterol, respectively). Plasma sitostanol levels were essentially undetectable. No difference was observed in cholesterol biosynthesis between tall oil (0.045 +/- 0.004 pools/d) and placebo (0.034 +/- 0.004 pools/d) treatments; however, the effect of treatments in subjects with different cholesterol levels varied. In subjects with lower cholesterol values, the red blood cell cholesterol fractional synthesis rate (FSR) increased from 0.0291 +/- 0.0054 pools/d after placebo to 0.0509 +/- 0.0049 pools/d (P < .05) after phytosterol treatment. In subjects with higher cholesterol values, the red blood cell cholesterol FSR did not change significantly after treatment. These results demonstrate the short-term efficacy of tall oil plant sterols as cholesterol-lowering agents.

Association of serine protease with the rise of intracellular calcium in cytotoxic T lymphocytes

The precise role of the granular enzyme A (granzyme A), a serine protease, in the lytic process of cytotoxic T lymphocytes (CTL) is not clear. We have recently constructed a CTL line transfected with the antisense gene of granzyme A (a-GrA). These a-GrA CTL had lower GrA activity as well as decreased lytic activities, as measured by 51Cr and by DNA degradation assays. Furthermore, at low effector:target ratio (1:8) in prolonged lytic assays, they could not lyse targets as rapidly as the control CTL. When we examined their ability to exocytose BLT (CBZ-L-lys-thiobenzyl)-esterase in the presence of anti-CD3 antibody, the a-GrA CTL exocytosed poorly compared to the parental CTL or control transfectant with a CAT gene. Most strikingly, a-GrA cells could not release intracellular stores of Ca2+ in response to anti-CD3 induction, although the Ca2+ flux was normal when they were stimulated with ionomycin. When the parental CTL was treated with a specific benzyllactam inhibitor of BLT-esterase or N-tosyl-L-phenylalanylchloromethyl ketone, the Ca2+ flux induced by anti-CD3 was also suppressed. We propose that granzyme A is involved in the signal transduction pathway that causes the rise of the intracellular calcium.

Assessing adequacy of mammographic image quality

High-quality mammographic images enhance the radiologist's ability to interpret mammograms with high sensitivity for detecting abnormalities and high specificity for classifying lesions suspicious for malignancy. In addition to proper exposure, contrast, resolution, compression, and positioning, high-quality mammographic images must be accompanied by pertinent history and available comparison images. To avoid negating the benefits of technically ideal images, mammograms must be viewed under optimal viewing conditions. Constant attention to quality control, with every image evaluated for adherence to strict technical standards, is essential for maintaining image quality.

Current serum levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin in phenoxy acid herbicide applicators and characterization of historical levels

BACKGROUND

Workers who sprayed phenoxy acid herbicides, especially those who sprayed before 1975, may have been exposed to significant amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent animal carcinogen present in herbicide preparations as a contaminant.

PURPOSE

The aims of this study were (a) to determine serum levels of TCDD in a representative sample of workers occupationally exposed to the agent during the spraying of phenoxy acid herbicides; (b) to compare serum levels in workers exposed before 1965, when concentrations in herbicide products were unregulated and high, with levels in workers exposed after 1974, when concentrations were lower as a result of government regulations worldwide; and (c) to examine the correlation, if any, between serum levels and duration of employment in spraying.

METHODS

Thirty-seven subjects were randomly selected from a group of 654 men who had sprayed the herbicides 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) in Australia for at least 12 months. The workers were classified as follows: eight who sprayed only before 1965, nine who sprayed only during the period after 1964 and before 1975, and 20 who sprayed during the period after 1974 and before 1991. Serum from the workers was analyzed for TCDD by high-resolution gas chromatography and high-resolution mass spectrometry at a detection limit of 0.6 parts per trillion (ppt) on a lipid-weight basis. In addition, rates of exposure to TCDD were estimated, as were TCDD serum concentrations at termination of employment and intensity of herbicide use.

RESULTS

Only one worker, with a serum TCDD level of 34 ppt, had a serum level higher than the maximum level of 26 ppt reported for the general population. Assuming a half-life of 7.1 years, we estimated the mean exposure rates to be 2.7, 2.3, and 0.06 ppt/mo for the three epochs, respectively. We found the highest serum level of TCDD at the time of cessation of employment to be 329 ppt. Calendar period and intensity of use of 2,4,5-T and 2,4-D were statistically significant determinants of rate of exposure to TCDD, but 2,4-D was associated with exposure rate only for the pre-1975 periods. Estimated rates prior to 1965 were more than an order of magnitude higher than those after 1974.

CONCLUSION

The highest estimated exposure rate was 20.7 ppt/mo, which suggests that some sprayers may have been exposed to levels comparable with those that produce cancer in laboratory animals.