CTIM-35. A PHASE II STUDY OF GITR AGONIST INCAGN01876 AND PD-1 INHIBITOR RETIFANLIMAB IN COMBINATION WITH STEREOTACTIC RADIOTHERAPY IN PATIENTS WITH RECURRENT GLIOBLASTOMA

BACKGROUND

We evaluated the combination of retifanlimab, INCAGN01876, and FSRT in patients with recurrent GBM.

METHODS

Phase II, single-center, 2 cohort study (A: single-arm non-surgical cohort; B, two-arm neoadjuvant/surgical cohort). Cohort A patients received pre-FSRT one-time doses of retifanlimab (500mg) and INCAGN01876 (300mg), FSRT (8 Gy x 3 fractions), and post-FSRT 28-day treatment cycles (retifanlimab, day 1; INCAGN01876, days 1, 15). Cohort B patients received pre-surgery doses of retifanlimab + INCAGN01876; subsequently, patients either went directly to resection (Sub-Arm 1) or to FSRT followed by resection (Sub-Arm 2). All patients resumed immunotherapy post-operatively. Primary endpoint: ORR in Cohort A. Data cut-off for this analysis was June 30, 2022.

RESULTS

Thirty-two evaluable patients: Cohort A, n=16; Cohort B, n=16 (Sub-Arm 1, n=8, Sub-Arm 2, n=8). Median follow-up time: Cohort A, 13.6 months; Cohort B, 8.8 months. Forty-four percent women, median age 64 (IQR, 55–65), 56% MGMT unmethylated. Most common grade 3/4 treatment-related AEs included cerebral edema (25%), lymphopenia (16%), and cognitive disturbance (13%). Efficacy in Cohort A: no objective responses observed, best response of stable disease achieved in 9/16 patients (56%), median PFS 3.9 months (95% CI 2.1 – 6.2 months), median OS 9.8 months (95% CI 8.3 months – not reached [NR]). Efficacy in Cohort B: median PFS NR, median OS 15.1 months (95% CI 8.5 months – NR). Median PFS and OS are longer in Cohort B Sub-Arm 2 compared to Cohort B Sub-Arm 1 (PFS, NR vs. 2.2 months, p = 0.009; OS, NR vs. 8.5 months, p=0.026). Results of tissue and blood-based immune correlative analyses will be presented.

CONCLUSIONS

The combination of retifanlimab, INCAGN01876, and FSRT is generally well-tolerated in patients with recurrent GBM when administered with or without surgical resection. Survival outcomes in the neoadjuvant cohort are encouraging, largely driven by patients that received neoadjuvant FSRT.

SARS-CoV-2 Seropositivity and Seroconversion in Patients Undergoing Active Cancer-Directed Therapy

PURPOSE

Multiple studies have demonstrated the negative impact of cancer care delays during the COVID-19 pandemic, and transmission mitigation techniques are imperative for continued cancer care delivery. We aimed to gauge the effectiveness of these measures at the University of Pennsylvania.

METHODS

We conducted a longitudinal study of SARS-CoV-2 antibody seropositivity and seroconversion in patients presenting to infusion centers for cancer-directed therapy between May 21, 2020, and October 8, 2020. Participants completed questionnaires and had up to five serial blood collections.

RESULTS

Of 124 enrolled patients, only two (1.6%) had detectable SARS-CoV-2 antibodies on initial blood draw, and no initially seronegative patients developed newly detectable antibodies on subsequent blood draw(s), corresponding to a seroconversion rate of 0% (95% CI, 0.0 TO 4.1%) over 14.8 person-years of follow up, with a median of 13 health care visits per patient.

CONCLUSION

These results suggest that patients with cancer receiving in-person care at a facility with aggressive mitigation efforts have an extremely low likelihood of COVID-19 infection.

Molecular Correlates of Long Survival in IDH-Wildtype Glioblastoma Cohorts

IDH-wildtype glioblastoma is a relatively common malignant brain tumor in adults. These patients generally have dismal prognoses, although outliers with long survival have been noted in the literature. Recently, it has been reported that many histologically lower-grade IDH-wildtype astrocytomas have a similar clinical outcome to grade IV tumors, suggesting they may represent early or undersampled glioblastomas. cIMPACT-NOW 3 guidelines now recommend upgrading IDH-wildtype astrocytomas with certain molecular criteria (EGFR amplifications, chromosome 7 gain/10 loss, and/or TERT promoter mutations), establishing the concept of a "molecular grade IV" astrocytoma. In this report, we apply these cIMPACT-NOW 3 criteria to 2 independent glioblastoma cohorts, totaling 393 public database and institutional glioblastoma cases: 89 cases without any of the cIMPACT-NOW 3 criteria (GBM-C0) and 304 cases with one or more criteria (GBM-C1-3). In the GBM-C0 groups, there was a trend toward longer recurrence-free survival (median 12-17 vs 6-10 months), significantly longer overall survival (median 32-41 vs 15-18 months), younger age at initial diagnosis, and lower overall mutation burden compared to the GBM-C1-3 cohorts. These data suggest that while histologic features may not be ideal indicators of patient survival in IDH-wildtype astrocytomas, these 3 molecular features may also be important prognostic factors in IDH-wildtype glioblastoma.

SARS-CoV-2 seropositivity and seroconversion in patients undergoing active cancer-directed therapy

Multiple studies have demonstrated the negative impact of cancer care delays during the COVID-19 pandemic, and transmission mitigation techniques are imperative for continued cancer care delivery. To gauge the effectiveness of these measures at the University of Pennsylvania, we conducted a longitudinal study of SARS-CoV-2 antibody seropositivity and seroconversion in patients presenting to infusion centers for cancer-directed therapy between 5/21/2020 and 10/8/2020. Participants completed questionnaires and had up to five serial blood collections. Of 124 enrolled patients, only two (1.6%) had detectable SARS-CoV-2 antibodies on initial blood draw, and no initially seronegative patients developed newly detectable antibodies on subsequent blood draw(s), corresponding to a seroconversion rate of 0% (95%CI 0.0-4.1%) over 14.8 person-years of follow up, with a median of 13 healthcare visits per patient. These results suggest that cancer patients receiving in-person care at a facility with aggressive mitigation efforts have an extremely low likelihood of COVID-19 infection.

Rethinking the interplay between affluence and vulnerability to aid climate change adaptive capacity

Affluence and vulnerability are often seen as opposite sides of a coin-with affluence generally understood as reducing forms of vulnerability through increased resilience and adaptive capacity. However, in the context of climate change and an increase in associated hazards and disasters, we suggest the need to re-examine this dynamic relationship-a complex association we define here as the Affluence-Vulnerability Interface (AVI). We review research in different national contexts to show how a more nuanced understanding of the AVI can (a) problematize the notion that increasing material affluence necessarily has a mitigating influence on social vulnerability, (b) extend our analysis of social vulnerability beyond low-income regions to include affluent contexts and (c) improve our understanding of how psychosocial characteristics influence people's vulnerability. Finally, we briefly outline three methodological approaches that we believe will assist future engagement with the AVI.

A prospective validation cohort study of baseline plasma cell-free DNA (cfDNA) as a prognostic biomarker in newly diagnosed glioblastoma (GBM)

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Background: Due to significant interpatient heterogeneity, survival outcomes vary widely in patients with GBM. Novel prognostic biomarkers are needed. We aimed to determine the prognostic impact of baseline plasma cfDNA concentration in patients with GBM. Methods: We analyzed 84 patients with newly diagnosed GBM and at least 7 months of follow-up time. The first 41 patients comprised a previously published derivation cohort (Bagley, Clin Cancer Res 2020). The subsequent 43 patients served as an independent validation cohort. cfDNA was extracted from plasma collected prior to initial surgical resection and quantified by qPCR for a 115 bp amplicon of the human ALU repeat element. Receiver operating characteristic (ROC) curve analysis was used in the derivation cohort to (1) assess the accuracy of plasma cfDNA concentration for predicting progression-free survival status at 7 months (PFS-7), a landmark based on the median PFS for newly diagnosed GBM (Stupp, N Engl J Med 2005), and (2) derive the optimal cutoff for dichotomizing patients into high- and low-cfDNA groups. In the validation cohort, logistic regression was used to measure the association of plasma cfDNA concentration (high vs. low) with PFS-7, adjusted for age, isocitrate dehydrogenase ( IDH) 1/2 mutational status, 0-6-methylguanine-methyltransferase ( MGMT) methylation, extent of resection, and performance status. Multivariate Cox regression was used for overall survival (OS) analysis. Results: In the derivation cohort, the optimal cutoff for plasma cfDNA was 25.0 ng/mL (area under the curve [AUC] = 0.663), with inferior PFS and OS in patients with cfDNA above this cutoff (PFS, median 4.9 vs. 9.5 months, log-rank p = 0.001; OS, median 8.5 vs. 15.5 months, log-rank p = 0.03). In the validation cohort, baseline plasma cfDNA concentration over the cutoff was independently associated with a lower likelihood of being alive and progression-free at 7 months (adjusted OR 0.13, 95% CI 0.02 – 0.75, p = 0.02). OS was also worse in in the validation cohort in patients with high plasma cfDNA (adjusted HR 3.0, 95% CI 1.1 – 8.0, p = 0.03). Conclusions: In patients with newly diagnosed GBM, high baseline plasma cfDNA concentration is associated with worse survival outcomes independent of other prognostic factors. Further validation in a larger, multicenter study is warranted.

Clinical Utility of Plasma Cell-Free DNA in Adult Patients with Newly Diagnosed Glioblastoma: A Pilot Prospective Study

PURPOSE

The clinical utility of plasma cell-free DNA (cfDNA) has not been assessed prospectively in patients with glioblastoma (GBM). We aimed to determine the prognostic impact of plasma cfDNA in GBM, as well as its role as a surrogate of tumor burden and substrate for next-generation sequencing (NGS).

EXPERIMENTAL DESIGN

We conducted a prospective cohort study of 42 patients with newly diagnosed GBM. Plasma cfDNA was quantified at baseline prior to initial tumor resection and longitudinally during chemoradiotherapy. Plasma cfDNA was assessed for its association with progression-free survival (PFS) and overall survival (OS), correlated with radiographic tumor burden, and subjected to a targeted NGS panel.

RESULTS

Prior to initial surgery, GBM patients had higher plasma cfDNA concentration than age-matched healthy controls (mean 13.4 vs. 6.7 ng/mL, P < 0.001). Plasma cfDNA concentration was correlated with radiographic tumor burden on patients' first post-radiation magnetic resonance imaging scan (ρ = 0.77, P = 0.003) and tended to rise prior to or concurrently with radiographic tumor progression. Preoperative plasma cfDNA concentration above the mean (>13.4 ng/mL) was associated with inferior PFS (median 4.9 vs. 9.5 months, P = 0.038). Detection of ≥1 somatic mutation in plasma cfDNA occurred in 55% of patients and was associated with nonstatistically significant decreases in PFS (median 6.0 vs. 8.7 months, P = 0.093) and OS (median 5.5 vs. 9.2 months, P = 0.053).

CONCLUSIONS

Plasma cfDNA may be an effective prognostic tool and surrogate of tumor burden in newly diagnosed GBM. Detection of somatic alterations in plasma is feasible when samples are obtained prior to initial surgical resection.

PATH-49. CLINICAL UTILITY OF PLASMA CELL-FREE DNA IN ADULT PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA – A PILOT PROSPECTIVE STUDY

BACKGROUND

Liquid biopsy has been not been widely utilized in patients with glioblastoma (GBM) compared to other solid tumors. However, the clinical utility of plasma cell-free DNA (cfDNA) in GBM has not been assessed prospectively or at the time of initial diagnosis.

METHODS

We conducted a prospective cohort study of patients with newly diagnosed GBM. Whole blood was collected in Streck® tubes at baseline prior to initial surgical resection and longitudinally during the course of adjuvant chemoradiotherapy. Plasma cfDNA concentration (ng/mL) was quantified by qPCR for a 115 bp amplicon of the human ALU repeat element, correlated with radiographic tumor burden by volumetry at multiple time points using Spearman rank correlation, and assessed for its impact on progression-free (PFS) and overall survival (OS) by Cox regression.

RESULTS

Prior to initial resection, GBM patients (N=42) had higher plasma cfDNA concentration compared to age-matched healthy controls (N=42) (mean 13.43 vs. 6.70 ng/mL, p< 0.001). Plasma cfDNA concentration was correlated with radiographic tumor burden on subjects’ first post-radiation MRI scan (r=0.77, p=0.003) and tended to rise prior to or concurrently with radiographic tumor progression. Pre-operative plasma cfDNA concentration above the mean (>13.4 ng/mL) was associated with inferior PFS (median 4.9 vs. 9.5 months, p=0.038) and OS (median 8.9 vs. 14.8 months, p=0.078). The impact on PFS persisted after adjusting for age, extent of resection, performance status, MGMT promoter methylation, and IDH1/2 mutational status (HR 2.48, 95% CI 1.1–6.1, p=0.046).

CONCLUSIONS

Plasma cfDNA may be an effective prognostic tool and noninvasive surrogate of tumor burden in newly diagnosed GBM. Tumor tissue samples from our cohort have been subjected to targeted next generation sequencing (NGS), and baseline plasma samples have been sent to Guardant Health for NGS. Plasma NGS results and concordance with matched tissue NGS will be included at time of presentation.

RBTT-05. A SINGLE-ARM, OPEN-LABEL, PHASE II STUDY EVALUATING THE EFFICACY AND SAFETY OF ABEMACICLIB IN PATIENTS WITH RECURRENT OLIGODENDROGLIOMA: TRIALS IN PROGRESS

BACKGROUND

Oligodendroglioma is a rare primary brain tumor characterized by mutation in the IDH1/IDH2 genes and codeletion of chromosomes 1p and 19q. Although median overall survival extends beyond 10 years for patients with oligodendroglioma who receive adjuvant radiation and alkylating chemotherapy, the disease uniformly relapses and has no other effective treatments. The CIC gene, which encodes a high-mobility group box transcriptional repressor, is mutated in about 70% of oligodendrogliomas and is associated with worse prognosis and overexpression of cyclin D1 (CCND1). Cyclin D1 assembles with the cyclin-dependent kinases CDK4 and CDK6 to cause phosphorylation of Rb protein and subsequent cell cycle progression from the G1 to S phase. Therapeutic inhibition of CDK4/6 activity, which leads to Rb dephosphorylation and cell cycle arrest, has revolutionized the care of breast cancer. The current phase 2 study will investigate the efficacy and safety of abemaciclib, a selective and potent small molecule inhibitor of CDK4 and CDK6 with significant brain-brain barrier penetration, in patients with 1p/19q codeleted oligodendroglioma that has recurred after standard radiation and alkylating chemotherapy.

METHODS

This protocol (NCT03969706) has a single-arm, open-label, single-stage phase 2 design. Subjects will be treated with abemaciclib 200mg tablet twice daily on 28-day cycles until disease progression or unacceptable toxicity. Tumor response will be assessed according to modified Response Assessment in Neuro-Oncology (mRANO) criteria. The primary objective of the study is to determine the efficacy of abemaciclib for recurrent oligodendroglioma. The primary endpoint is the progression-free survival status of the subject at 6 months after enrollment (PFS-6). The alternative hypothesis is that the proportion of subjects without an event at 6 months will be ³85%. We will test this hypothesis against a null hypothesis of PFS-6 = 50%. With enrollment of 10 planned subjects, the power to detect this difference is 82% (one-sided alpha = 0.05).

Are fetuses that fail to achieve their growth potential at increased risk of intrapartum compromise?

OBJECTIVE

The true growth potential of a fetus is difficult to predict but recently a new definition, independent of fetal weight, using cerebroplacental (cerebro-umbilical) ratio (CPR) < 0.6765 multiples of the median (MoM), was reported. We applied this definition to a cohort of low-risk pregnancies recruited prospectively to determine if fetuses with CPR < 0.6765 are at increased risk of developing signs of intrapartum fetal compromise.

METHODS

Recruitment to this prospective observational study took place between March 2011 and March 2014. All women with low-risk singleton pregnancies at term were eligible. Women with known or suspected placental dysfunction were excluded, as were women with fetuses with an estimated fetal weight < 10(th) centile. All participants underwent ultrasound examination prior to active labor (≤ 4 cm cervical dilatation), during which fetal biometry as well as umbilical artery and fetal middle cerebral artery blood flow were assessed. Following delivery, intrapartum and neonatal outcomes were compared between fetuses that had a CPR < 0.6765 MoM and those that had a CPR ≥ 0.6765 MoM.

RESULTS

In total, 775 women were recruited. Fetuses with CPR < 0.6765 MoM were significantly more likely to require Cesarean delivery because of presumed fetal compromise (P < 0.001). These fetuses were also at increased risk of compromise at any time during labor and were less likely to be delivered vaginally, spontaneously or otherwise, than were those with CPR ≥ 0.6765 MoM. CPR < 0.6765 MoM gave a positive predictive value (PPV) for Cesarean delivery because of presumed fetal compromise of 36.7% and a negative predictive value of 88.7%, with a sensitivity of 18% and a specificity of 95.4%.

CONCLUSION

Fetuses that failed to achieve their growth potential (defined as CPR < 0.6765 MoM) were at increased risk of intrapartum compromise and were less likely to be delivered vaginally. However, a low negative predictive value was observed for fetal compromise and further studies are required to support the translation of this technique into clinical practice.

Influence of parity on fetal hemodynamics and amniotic fluid volume at term

OBJECTIVES

Pregnancy complications, particularly those associated with placental dysfunction, occur more frequently in nulliparous than in parous women. This difference may be a consequence of improved trophoblastic invasion and, as a result, improved placental function following previous pregnancy. Placental dysfunction in cases of fetal growth restriction may be identified by ultrasound assessment of fetoplacental hemodynamics and amniotic fluid volume. In this prospective observational study, we investigated whether differences in these measures of placental function exist between nulliparous and parous women, prior to active labor.

METHODS

Over a 2-year period, 456 nulliparous and 152 parous women with uncomplicated singleton pregnancies were recruited to this prospective observational study. Each participant underwent an ultrasound assessment prior to active labor, during which fetal biometry, umbilical artery, middle cerebral artery and umbilical venous Dopplers, as well as amniotic fluid volume, were assessed. All cases were followed up within 48 h of delivery. Ultrasound parameters and intrapartum outcomes were then compared between the nulliparous and parous groups.

RESULTS

Compared with nulliparous women, parous women had significantly higher fetal middle cerebral artery pulsatility index, cerebroplacental ratio and amniotic fluid volume. In nulliparous women, middle cerebral artery flow rate was also significantly higher and represented a greater percentage of umbilical venous flow than was observed in parous women.

CONCLUSION

Prior to the active phase of labor, ultrasound parameters indicative of placental function differ significantly between nulliparous and parous pregnancy, even amongst an uncomplicated, low-risk cohort.

A novel fluorescent "turn-on" chemosensor for nanomolar detection of Fe(III) from aqueous solution and its application in living cells imaging

An electronically active and spectral sensitive fluorescent "turn-on" chemosensor (BTP-1) based on the benzo-thiazolo-pyrimidine unit was designed and synthesized for the highly selective and sensitive detection of Fe(3+) from aqueous medium. With Fe(3+), the sensor BTP-1 showed a remarkable fluorescence enhancement at 554 nm (λex = 314 nm) due to the inhibition of photo-induced electron transfer. The sensor formed a host-guest complex in 1:1 stoichiometry with the detection limit down to 0.74 nM. Further, the sensor was successfully utilized for the qualitative and quantitative intracellular detection of Fe(3+) in two liver cell lines i.e., HepG2 cells (human hepatocellular liver carcinoma cell line) and HL-7701 cells (human normal liver cell line) by a confocal imaging technique.

Sustainable governance of scarce metals: the case of lithium

Minerals and metals are finite resources, and recent evidence suggests that for many, primary production is becoming more difficult and more expensive. Yet these resources are fundamentally important for society--they support many critical services like infrastructure, telecommunications and energy generation. A continued reliance on minerals and metals as service providers in modern society requires dedicated and concerted governance in relation to production, use, reuse and recycling. Lithium provides a good example to explore possible sustainable governance strategies. Lithium is a geochemically scarce metal (being found in a wide range of natural systems, but in low concentrations that are difficult to extract), yet recent studies suggest increasing future demand, particularly to supply the lithium in lithium-ion batteries, which are used in a wide variety of modern personal and commercial technologies. This paper explores interventions for sustainable governance and handling of lithium for two different supply and demand contexts: Australia as a net lithium producer and Switzerland as a net lithium consumer. It focuses particularly on possible nation-specific issues for sustainable governance in these two countries' contexts, and links these to the global lithium supply chain and demand scenarios. The article concludes that innovative business models, like 'servicizing' the lithium value chain, would hold sustainable governance advantages for both producer and consumer countries.

A new approach to identify species in Xiphinema americanum sensu lato

Four putative species belonging to the X. americanum group are known to transmit American nepoviruses and these nematodes and viruses are listed in European quarantine legislation. Identification of species in this group is therefore of particular importance for phytosanitary purposes, but is problematic because of the similar morphology of the putative species. As part of the Synthesys project BE-TAF 1769, eight collaborative institutions contributed material to Fera for study. Video technology allowed the best records of type material and in conjunction with photographic images created a 'virtual' collection of images that relies less on the deteriorating quality of museum specimens. Revised definitions of lip region and tail shape are considered to be the most stable characters for differentiation. Position of the amphidial aperture, development of the odontostyle collar and some established morphometric characters are considered of limited use although they retain value for latter stages of identification.

Outcomes of radical conformal radiotherapy and concomitant cisplatin chemotherapy for olfactory neuroblastoma—Review of a single centre experience

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Background: Olfactory neuroblastoma is rare with 25 new cases annually in the UK. Cranio-facial resection and post operative radiotherapy is standard treatment. The use of concomitant chemotherapy has not been fully evaluated, although chemo-sensitivity has been demonstrated by retrospective series. This study evaluates the use of radical radiotherapy and concomitant chemotherapy. Methods: Since 1978 more than 70 patients have been seen at the Institute of Otology and Laryngology. Eighteen patients treated with radiotherapy between 1999 and 2005 were reviewed. These were all CT planned and treated with conformal radiotherapy ± cisplatin chemotherapy 100 mg/m2 D 1, 22 and 43. The radiotherapy prescribed dose varied from 50Gy to 62 Gy in 1.8 to 2 Gy fractions, 10 (56%) received 60Gy in 30 fractions. Overall survival, disease free survival and treatment related morbidity were assessed. Results: Seventeen patients were post operative and 1 was neo-adjuvant. Mean age was 46 years (range 20–83) and the majority were Kadish stage C. Of the 17 post-operative patients, 13 (76%) had surgery as primary treatment and 4 (24%) for recurrence. Eight patients (44%) received concomitant chemotherapy. At the time of analysis follow up ranged from 4 months to 72 months (median 17.5, mean 28.2), 16 (88.9%) patients were alive and 14 (77.8%) disease free. Four (22.2%) patients developed recurrence and 2 died of disease. Of the 4 patients with recurrence, 3 did not receive concurrent cisplatin chemotherapy and the fourth patient did not undergo radical surgery. No patients reported deterioration in vision or significant morbidity following treatment. Conclusions: Post operative radiotherapy with concurrent cisplatin chemotherapy is effective and well tolerated in the management of olfactory neuroblastoma. Where concurrent chemotherapy was not given, relapse rates were high. Our results, although immature, suggest disease free survival superior to published data. A prospective multi-centre study to evaluate concomitant treatment schedules is required.

No significant financial relationships to disclose.

Phenotypic differences in cholinergic responses of distal colonic epithelium

The Flinders sensitive line (FSL) rats exhibit an increased cholinergic responsiveness in vivo when compared to their counterparts, the Flinders resistant line (FRL) rats. The functional consequences of this phenotypic difference on colonic mucosal function are not known. We sought to determine whether isolated distal colonic mucosa from the two strains exhibit differential responses to cholinergic agonists. The responses of the distal colonic mucosa from two lines of rats to carbachol were compared by recording changes in short-circuit current. The ion movements associated with these changes were assessed by flux analysis of the radiotracers, 22Na and 36Cl. The anticipated hyper-responsiveness to cholinergic stimulation in FSL rats was not seen. Carbachol responses were significantly enhanced by indomethacin pretreatment only in FRL rats. Tetrodotoxin (TTX) pretreatment significantly reduced responses to carbachol in FSL rats at all concentrations tested, though this was only seen with lower concentrations in FRL rats. Flux analysis indicated that both lines absorbed Na+ and Cl- under basal conditions and that a significant residual flux was present. Stimulation with carbachol led to significant reductions in net Na+ and Cl- fluxes in both lines. The changes in net Na+ and Cl- flux in both lines stem largely from a decrease in mucosal to serosal fluxes of both ions with an increase in serosal to mucosal flux of Cl-. The striking difference is the significant reduction in residual flux seen only in FRL rats. Indomethacin pretreatment abolished the changes in residual flux seen in FRL rats. Thus the responses to carbachol in these rats had at least three components: (a) a direct effect on the transporting colonocyte, (b) an indirect effect mediated by an arachidonic acid metabolite, and (c) another indirect effect involving a neurotransmitter. The relative contributions of each of these components were different in the two lines.

Calcium-stimulated short-circuit currents in the canine proximal colonic epithelium: effects of DK-PGD2, a metabolite of prostaglandin D2

Prostaglandin D2 (PGD2) has marked inhibitory effects on the canine proximal colonic epithelium set up in Ussing chambers. These effects involved a receptor that is pharmacologically distinct from the classical DP, presumably the recently identified CRTH2/DP2 variety. The mechanism underlying these effects was studied using 13,14-dihydro-15-keto-PGD2 (DK-PGD2), a stable metabolite of the parent prostanoid. The metabolite quickly reversed short circuit currents (I(sc)) stimulated by diverse agonists. Greater inhibitory effects were seen with stimulants such as carbachol and cyclopiazonic acid (CPA) rather than with forskolin or protein kinase A activators. Since the same stimulants were differentially affected by removal and replacement of serosal Ca2+, we tested the possibility that the prostanoid inhibited basolateral Ca2+ entry. In the absence of serosal Ca2+, tissues primed with CPA demonstrated concentration-dependent increases in I(sc), to cumulative additions of Ca2+ or Sr2+, though the former was more potent. Cl- removal and pretreatment with bumetanide virtually abolished responses, suggesting that the increase in I(sc) reflected Ca2+ dependent Cl- secretion. Though responses were insensitive to the L-type channel antagonist, verapamil, a marked inhibition was seen in the presence of metal cations (Gd3+, Cd2+, and La3+). Pretreatment with DK-PGD2 inhibited responses to Ca2+ in CPA-primed tissues. Thus, basolateral Ca2+ entry via store-operated Ca2+ channels may be the locus for the inhibitory effects of PGD2 in this tissue. These results could indicate a potential transduction mechanism for the novel DP receptor variously called CRTH2 or DP2.

Foods, health claims, and the law: comparisons of the United States and Europe

Government, academia, and the food industry can play a significant role in the identification of healthy foods and ingredients important for weight management and health. The U.S. Food and Drug Administration developed regulations that define specific food categories for weight management and health. These categories include foods for special dietary uses and medical foods. Medical foods are classified for use in specific disease states and require a physician's recommendation and continuous monitoring. The European regulations specify energy-restricted foods as a subcategory of food for particular nutritional uses, which includes infant formula, medical foods, and foods for sports. European standards for energy-restricted diets have been established, leaving little flexibility for change. Three categories exist (i.e., very-low-calorie diets [450 to 800 kcal], low-calorie diets [800 to 1200 kcal], and meal replacements [200 to 400 kcal]). No claims on anticipated weight loss can be made even where significant clinical research has demonstrated long-term efficacy, thereby preventing informed choice management. Dramatic changes in lifestyle (e.g., disruption of the family unit, altered eating occasions, fast foods, and food grazing) have resulted in an epidemic of obesity and chronic disease. Regulating food selection or dietary patterns to limit the epidemic is not realistic. However, stimulating government health agencies and the food industry to increase public awareness through educational programs and regulating the definition of acceptable methods and products can provide an environment for change. A consensus is needed among academia, government, and industry for appropriate food labeling and claims. These actions are needed to help individuals make healthy food selections and maintain a healthy weight. Public health initiatives should change consumer attitudes with programs that are simple, affordable, effective, and accessible.

Chronic stress impairs rat growth and jejunal epithelial barrier function: role of mast cells

We examined the impact of chronic stress on rat growth rate and intestinal epithelial physiology and the role of mast cells in these responses. Mast cell-deficient (Ws/Ws) rats and +/+ littermate controls were submitted to water avoidance stress or sham stress, 1 h/day, for 5 days. Seven hours after the last sham or stress session, jejunal segments were mounted in Ussing chambers, in which secretion and permeability were measured. Body weight (as a growth index) and food intake were determined daily. Stress increased baseline jejunal epithelial ion secretion (indicated by short-circuit current), ionic permeability (conductance), and macromolecular permeability (horseradish peroxidase flux) in +/+ rats, but not in Ws/Ws rats, compared with nonstressed controls. Stress induced weight loss and reduced food intake similarly in the groups. In +/+ rats, these parameters remained altered 24-72 h after the cessation of stress. Modulation of stress-induced mucosal mast cell activation may help in the management of certain intestinal conditions involving epithelial pathophysiology.

Probing the "active site" of diamine oxidase: structure-activity relations for histamine potentiation by O-alkylhydroxylamines on colonic epithelium

The responses of the canine colonic epithelium to histamine are potentiated by O-alkylhydroxylamines. A study of a series of such compounds suggested that active compounds had the structure R-O-NH2, substitution of a nitrogen led to total loss of activity. The locus of the potentiation effect was traced to the inhibition of diamine oxidase. A new series of aliphatic and aromatic O-alkylhydroxylamines were synthesized to explore further the structure-activity relations of this effect. The potentiating effects of these compounds were determined by examining the changes in short circuit current (Isc) produced by histamine and from the activity of a soluble preparation of diamine oxidase. We found that 1) branched compounds are less active than their straight chain counterparts, 2) greater steric bulk of the aliphatic substituent decreased activity, 3) the presence of a double bond had no significant effect though a triple bond reduced activity, 4) longer straight chain compounds were less active than the shorter chain derivatives and 5) all benzylic compounds were less active than the straight chain aliphatics. O-1-benzyl was inactive however the meta or para oxygen substituted compounds as well as the O-(1-E-Cinnamyl) derivative were active. A current model for the action of diamine oxidase proposes a crucial role for a trihydroxyphenylalanine quinone cofactor as part of the active site together with a copper atom. Using molecular modeling based on our inhibition data we are able to define the region of space that is just beyond the reactive carbonyl of the trihydroxyphenylalanine residue at the active site of diamine oxidase. We suggest that a negatively charged species, such as an aspartate or a glutamate, resides in a trough about 7 to 8 A from the trihydroxyphenylalanine carbonyl carbon and this species aids in the strong selective binding of substrates such as putrescine and histamine.

Ineffectiveness of the presence of H-ras/p53 combination of mutations in squamous cell carcinoma cells to induce a conversion of a nontumorigenic to a tumorigenic phenotype

Human tumor cells have properties in vitro or in surrogate hosts that are distinct from those of normal cells, such as immortality, anchorage independence, and tumor formation in nude mice. However, different cells from individual tumors may exhibit some, but not all of these features. In previous years, human tumor cell lines derived from different tumor and tissue types have been studied to determine those molecular changes that are associated with the in vitro properties listed above and with tumorigenicity in nude mice. In the present study, seven cell lines derived from human tumors were characterized for p53 and ras mutations that may occur in SCC tumor phenotypes and for tumor formation in nude mice. This investigation was designed to examine whether co-occurrence of mutated ras and p53 lead to a malignant stage in the progression process. None of the seven cell lines contained mutations in the recognized "hot spots" of the p53 tumor suppressor gene, but four had a nonsense/splice mutation in codon 126 and a mutation in codon 12 of the H-ras gene. The remaining three cell lines had p53 mutations in intron 5, in codon 193, and a missense mutation in codon 126, respectively. Four of seven cell lines were nontumorigenic; two of these cell lines contained a nonsense p53-126 mutation and mutated ras; one had a missense mutation at codon 126 but no mutated ras; the the fourth had only a p53 mutation at codon 193. Two of the nontumorigenic cell lines were converted to tumorigenicity after treatment with methyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine with no apparent additional mutations in either gene. Our analysis revealed that there was a high frequency of genetic diversity and mutations in both p53 and H-ras. There was also a lack of a causal relationship in the presence of mutations in p53 and the cells' ability to exhibit a malignant potential in nude mice.

Functional subtyping of histamine receptors on the canine proximal colonic mucosa

The receptors involved in the neural and non-neural effects of histamine on the canine proximal colon in vitro were defined functionally by using selective agonists and antagonists. Two preparations, a ganglionated mucosa and an aganglionated epithelium, were set up in Ussing chambers and short-circuit currents were monitored. The mucosa was obtained by removing the circular and longitudinal muscles, but keeping intact the muscularis mucosa and attendant submucosal plexuses, whereas the epithelium was devoid of that layer as well. On the mucosal preparation, histamine, 2-methylhistamine (2-MH) and 2-pyridylethylamine (PEA), a histamine (H)1-selective agonist elicited responses which were inhibited by pretreatment with tetrodotoxin and H1 antagonists (mepyramine). Responses to dimaprit (H2 agonist) were seen only at high concentrations and these were unaffected by tetrodotoxin; no responses were noted with any of the other agonists tested. By contrast, responses on the epithelial preparation were seen with histamine as well as H1 (PEA and 2-MH), H2 (dimaprit, impromidine and 4-MH) and H3-selective agonists [R(-)-alpha-MH]. Responses to PEA were inhibited selectively by mepyramine (H1 antagonist), whereas those elicited by H2 agonists were antagonized only by ranitidine (H2 antagonist). Both mepyramine and ranitidine significantly reduced the epithelial responses of 2-MH. Responses to [R(-)-alpha-MH] (H3 agonist) were seen only at high concentrations and were inhibited by ranitidine, but not by thioperamide (H3 antagonist). The effects of histamine were unaffected by pretreatment with indomethacin. Thus, neural effects are mediated by the occupation of H1 receptors (presumably on the submucosal neurons), whereas the non-neural (direct) effects result from the occupation of either H1 or H2 receptors. H3 receptors are functionally absent. Flux experiments showed that histamine, dimaprit and PEA produced marked increases in short circuit current that were accompanied by significant increases in JsmCl leading to decreases in JnetCl. Dimaprit stimulated an increase in JnetNa, largely as a result of increases in JmsNa. A negative residual flux (Jres) was seen with all three agonists. Thus, neural effects involve H1 receptors; non-neural effects involve both H1 and H2 receptors. Cl- secretion results from occupation of either receptor subset. Only the selective H2-agonist, dimaprit, produced significant changes in JnetNa. H3 receptors are functionally absent.

Adenosine A1 receptors are not involved in contraction of canine gastric muscularis mucosae by adenosine analogues

In vitro contractility studies were conducted in canine gastric muscularis mucosae muscle strips with the adenosine analogues 2-chloroadenosine (CIAD), 5'-N-ethylcarboxamidoadenosine (NECA), 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA), R-N6-(2-phenylisopropyl)adenosine (R-PIA), S-PIA, N6-cyclohexyladenosine (CHA) and (2-p-carboxyethyl)phenylamino-5'-N-carboxamidoadenosine (CGS21680) as well as the A1-selective antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). Adenosine analogues contracted the muscle strips with the following rank order of potency: CPCA > NECA > CIAD > R-PIA > CHA > S-PIA > CGS21680. CPCA, R-PIA, and CHA were partial agonists. At a concentration selective for adenosine A1 receptors (50 nM), DPCPX did not alter the concentration-response curves to CIAD or CHA. However, at higher concentrations (1-10 microM), DPCPX antagonized CIAD-mediated contractions in a competitive manner (pA2 = 6.96; slope = 0.93). CIAD-mediated contraction was not altered by treatment of the muscle strips with tetrodotoxin (1 microgram/ml) or mepyramine (1 microM). Our results indicate that adenosine A1 receptors, nerves or mast cells are not involved in contraction of canine gastric muscularis mucosae by adenosine analogues.

Effects of bradykinin on the canine proximal colon

The canine proximal colon set up in Ussing chambers responded to the serosal addition of bradykinin (BK) with changes in short-circuit current (Isc). Two preparations were used to analyze these effects - an innervated mucosal preparation and a 'functionally nerve-free' epithelial preparation. The specific questions that this study sought to answer were (1) is there a significant neural component to the effects noted?, and (2) what is the receptor subtype involved? BK produced dose-dependent increases across both the mucosa and the epithelial preparations. A secondary decrease in Isc was noted in the mucosal but not the epithelial preparation. Tetrodotoxin (TTX) significantly inhibited the magnitude of mucosal responses and delayed their onset as well, indicating the presence of a significant neural component. Addition of the B2 antagonist, D-Arg0[Hyp3,Thi5,8, D-Phe7]BK produced a surmountable inhibition of the responses to the agonist. The B1 selective agonist, des-Arg9BK produced increases in Isc across both preparations, though TTX had no significant effects on these responses. Cross-desensitization was seen between BK and des-Arg9 BK. However, since the B1 selective antagonist, des-Arg9[Leu8]BK acted as a partial agonist in our preparation, these effects could not be defined further. Clearly, B2 receptors are involved in mediating canine colonic BK responses, however the role of B1 receptors in this tissue requires further definition.

Characterization of translational frame exception patients in Duchenne/Becker muscular dystrophy

The clinical progression of Duchenne muscular dystrophy (DMD) patients with deletions can be predicted in 93% of cases by whether the deletion maintains or disrupts the translational reading frame (frameshift hypothesis). We have identified and studied a number of patients who have deletions that do not conform to the translational frame hypothesis. The most common exception to the frameshift hypothesis is the deletion of exons 3 to 7 which disrupts the translational reading frame. We identified a Becker muscular dystrophy (BMD) patient, an intermediate, and a DMD patient with this deletion. In all three cases, dystrophin was detected and localized to the membrane. One DMD patient with an inframe deletion of exons 4-18 produced no dystrophin. One patient with a mild intermediate phenotype and a deletion of exon 45, which shifts the reading frame, produced no dystrophin. Two patients with large inframe deletions had discordant phenotypes (exons 3-41, DMD; exons 13-48, BMD), but both produced dystrophin that localized to the sarcolemma. The DMD patient, 113, indicates that dystrophin with an intact carboxy terminus can be produced in Duchenne patients at levels equivalent to some Beckers. The dystrophin analysis from these patients, together with patients reported in the literature, indicate that more than one domain can localize dystrophin to the sarcolemma. Lastly, the data shows that although most patients show correlation of clinical severity to molecular data, there are rare patients which do not conform.

H1 contractile and H2 relaxant receptors in canine gastric muscularis mucosae

Histamine had two effects on the contractility of canine gastric muscularis mucosae in vitro: relaxation at or below 10 microM and contraction at higher concentrations. Selective agonists and antagonists were used to test the possibility that these effects were mediated by different receptor subtypes. The H1-selective agonist 2-pyridylethylamine (2-PEA) and the H2-selective agonist dimaprit contracted and relaxed this muscle, respectively, while the H3-selective agonist R-alpha-methylhistamine had no effect. The H1- and H2-selective antagonists mepyramine and ranitidine selectively blocked 2-PEA-mediated contractions and dimaprit-mediated relaxations, respectively. Agonist responses, were unaltered by tetrodotoxin, suggesting a site of action other than nerves. Our results indicate that canine gastric corpus muscularis mucosae possesses both contractile H1 and relaxant H2 receptors.

Histamine potentiation by hydroxylamines: structure-activity relations; inhibition of diamine oxidase

Hydroxylamines potentiated the responses of the canine colonic epithelium to histamine but not to other agonists such as serotonin or carbachol. We tested the hypothesis that an inhibition of histamine catabolism could explain the observed potentiation. A clear structure activity relation was defined, active compounds having the structure NH2-O-R, R being a simple uncharged aliphatic group. Active compounds delayed the disappearance of histamine from the bathing solutions and inhibited colonic diamine oxidase, an effect mimicked by standard inhibitors aminoguanidine and semicarbazide. Histamine agonists that possessed an imidazole nucleus (2- and 4-methylhistamine) were affected, whereas impromidine, 2 pyridylethylamine, and dimaprit were not. Agonist specificity combined with the enzyme data suggest an inhibition of histamine catabolism as a possible mechanism for the potentiating effects observed.

Epithelial and mucosal preparations from canine colon: responses to substance P

The hypothesis that substance P (SP) elicits both direct and indirect responses on the canine proximal colon was tested using two different in vitro preparations. The mucosa contained the muscularis mucosa and the attendant submucosal plexuses whereas the epithelium, being devoid of both, was functionally "nerve-free." Dose-dependent stimulation was noted on both preparations, increases in peak current (microamperes per squared centimeter) as well as charge transfers (millicoulombs per squared centimeter) were monitored. Tetrodotoxin significantly reduced mucosal responses whereas atropine and the H1 antagonists mepyramine and diphenhydramine had only marginal effects. None of these agents affected the responses of the epithelium to SP. Indomethacin significantly reduced responses in both preparations. Removal of Na+ or Cl- or the use of C- channel blockers (9-anthracene carboxylic acid and N-phenylanthranilic acid) produced a significant reduction of SP responses across the epithelium. Thus, SP has both direct and indirect affects on the colon; activation of the cyclooxygenase pathway could be significant.

Carrier detection in Duchenne muscular dystrophy: a review of current issues and approaches

The clinical chemistry laboratory has traditionally played a passive role in the application of technology to diagnostic interpretation. Recent developments offer the clinical laboratorian a renewed potential to enter the patient care arena as a consultant. Our lack of understanding of the disease processes in the muscular dystrophies places emphasis on prevention through carrier detection. This review summarizes the clinical progress of the disease, our present understanding of the genetics that control the mode of inheritance of the disease, and the analytical approaches to carrier detection, including their advantages and limitations. Recent advances allow the examination of the genetic material itself instead of concentrating on the phenotypic expression of biochemical abnormalities.