Calcareous termite mounds in South Africa are ancient carbon reservoirs

Ecosystems that offer carbon sequestration by leaching bicarbonate to groundwater are valuable natural capital. One region that may offer this service is the west coast of South Africa. Over 20 % is covered by soil mounds ("heuweltjies") up to 40 m diameter, 2 m high, inhabited by the southern harvester termite Microhodotermes viator and enriched in soil organic and inorganic carbon and soluble minerals. We aimed to generate radiogenic and stable isotope data for soils and groundwater in a region where these data are absent, to 1) verify the atmosphere-soil-groundwater link, and 2) resolve the timing and pattern of calcite dissolution and water infiltration in the landscape. Results show that soil and groundwater sulfate have the same marine aerosol source. Episodic calcite dissolution in mound centers, which increased during periods of global cooling, has been set against background input of marine aerosols since before the Last Glacial according to radiocarbon (14C) ages. Our data push back soil organic carbon 14C ages of inhabited termite mounds to 13-19 ka (kiloannum, thousand years before present), nest carbonate 14C ages to 33 ka, and mound soil carbonate 14C ages to 34 ka, making these the oldest active termite features ever dated. These ages are consistent with soil organic carbon and carbonate 14C ages of regional, non-mound, coastal petrocalcic horizons formed by accumulation of carbonate leached from their overlying aeolian dune fields. Harvesting activities of termites inject younger organic material around nests >1 m deep, leading to continuous renewal of important soil carbon reservoirs at depth. Termite bioturbation increases the system's ability to dissolve carbonate. The central, bioturbated part of the mounds have greater infiltration depths and greater calcite dissolution, whereas surrounding soils experienced more surface runoff. Calcareous termite mounds offer a mechanism to sequester CO2 through dissolution and leaching of soil carbonate-bicarbonate to groundwater.

Understanding amphidromy in Hawai'i: 'O'opu nākea (Awaous stamineus)

Hawai'i is home to 'o'opu nākea (Awaous stamineus), a culturally significant, endemic, goby that exhibits an amphidromous life cycle characterized by a marine larval stage followed by post-larval recruitment to streams, where they live to become reproductive adults. However, it was recently suggested that their migration to the ocean might not be obligatory, as originally thought. Despite their importance in Hawaiian traditions and the ecology of Hawaiian freshwater ecosystems, we still lack a full understanding of their migratory patterns and life history due to the difficulties in determining the environmental migratory cues that set the timing and location of their migratory paths. This study examined environmental factors, such as mean annual rainfall, streamflow, and water chemistry, to determine if they play a role in whether A. stamineus spend their larval period in the ocean or their entire life cycle in freshwater streams. We sampled A. stamineus (n = 90) from three streams (Kahana, Kahalu'u, and Waimānalo) on the island of O'ahu, Hawai'i that represented the range of hydroclimatic gradient in wet-habitat conditions on the windward side of the island and characterized their migratory pattern using elemental analysis of sagittae, the largest pair of otoliths (calcareous ear structures). Based on otolith strontium:calcium and barium:calcium ratios, we determined if individuals spent their larval period in the ocean or the stream. We found that 100% of individuals displayed clear evidence of marine residence during their larval phase, regardless of the environmental factors the fish experienced. This study highlights the necessity of stream-ocean connectivity for the survival of A. stamineus and emphasizes the importance of stream-mouth conservation and management as it is a critical transition zone in stream-ocean-stream migratory pathways.

Oral Cavity Squamous Cell Carcinomas in Patients with a History of Oral Lichen Planus: Frequency and Outcomes

PURPOSE/OBJECTIVE(S)

Oral lichen planus (OLP) is an inflammatory condition which affects the mucous membranes of the oral cavity. While previous studies have described the association between OLP and development of oral cavity cancer, there is currently a paucity of literature examining the impact of this disease on treatment response and prognosis. As such, we present a retrospective cohort study of Oral cavity squamous cell carcinoma (OCSCC) patients with a history of OLP to explore the course of their disease.

MATERIALS/METHODS

Using an IRB approved tertiary care registry of head and neck cancer patients, we identified patients with OCSCC who had a prior diagnosis of OLP. The number of new primary tumors, rates of local (LF), regional (RF) and distant failure (DF), as well as overall survival (OS) were assessed using Cox proportional hazards and Kaplan Meier analysis for actuarial survival estimates.

RESULTS

Fifty-four patients with OCSCC and OLP were identified with 109 individual OCSCC diagnoses. Patients had a median age of 67 years, were predominantly female (n = 42, 77.8%) and never smokers (n = 29, 53.7%) with a median follow up after diagnosis of OCSCC of 46.5 months. Nine patients (16.7%) had a history of immunosuppression of whom 6 (11.1%) had chronic steroid use for treatment of OLP. Within the cohort, 33 (61.1%) of OLP patients had a single OCSCC, 11 (20.4%) had 2, and 10 (18.5%) had >3 separate tumors develop. The most common oral cavity subsites were oral tongue (n = 42, 38.5%), followed by alveolar ridge (n = 14, 12.8%) and gingiva (n = 13, 11.9%). Papillary SCC subtype was identified in 10.1%. 92.7% of tumors (n = 101) were treated with primary surgery, with 23 (21.1%) receiving adjuvant RT and 10 of those patients receiving concurrent chemotherapy. Among resected patients, pathologic stages were predominantly T1-2 (84.1%) and N0 (50% vs N1 15.6% and N2a-3 34.4%). The mean RT dose was 62 Gy in 32 fractions. Locoregional failure occurred in 24.8% of cancers (n = 27), with local and regional failure occurring in 13.8% (n = 15) and 11% (n = 12) of lesions, respectively. Recurrence free survival at 3 and 5 years was 75% and 70.3%, respectively, with overall survival at 3 and 5 years of 71.1% and 67%, respectively.

CONCLUSION

Patients with OCSCC and a history of OLP are predominantly female and never smokers. The tumors that develop in such patients are often early stage but a proportion of patients appear to be at higher risk of developing multiple malignancies and surveillance of this patient population to identify new tumors is crucial.

Stereotactic Body Radiation Therapy (SBRT) for Head and Neck Cancer Re-Irradiation: Should >180˚ Carotid Encasement or Dermal Involvement Remain an Exclusion Criteria?

PURPOSE/OBJECTIVE(S)

Patients with recurrent head and neck cancer (HNC) who present with carotid encasement (CE) >180˚ and skin involvement/abutment (SI/A) are often not considered for SBRT re-irradiation and are excluded from RTOG 3507. We reviewed our institutional experience of SBRT re-irradiation in such cases.

MATERIALS/METHODS

From an IRB approved registry, we identified previously irradiated HNC patients treated by SBRT with CE >180˚, SI/A, or use of bolus from 2013-2022. Toxicity as per CTCAEv4.0 and recurrence patterns were analyzed. The cumulative incidence of local progression was estimated with death as a competing risk. Survival analysis was performed with the Kaplan-Meier method.

RESULTS

Thirty-five patients were treated with SBRT to 37 sites with median follow up of 5.7 months (mo) (IQR 2.7-10.6). A total of 20 cases exhibited CE >180˚, 20 cases had SI/A, and 3 cases had both. The median time from prior radiation was 12.7 mo (range 1.9-144.1). Histology was squamous cell carcinoma in 89%. The site of SBRT was most commonly the neck (65%), 24% mucosa, 8% skull base, and 3% scalp. SBRT was delivered in 5 fractions every other day (62%) or 2 fractions per week (38%). 78% (N = 29) received ≥40 Gy while 22% (N = 8) received a lower dose. The cumulative incidence of local failure at 3 and 6 mo was 12.4% (95% CI 0.8-24.0) and 31.3% (95% CI 14.9-47.8), respectively. The median time of local and regional recurrence free survival was 7.0 and 4.9 mo. Median OS was 8.3 mo. Of the 20 cases with true SI, 40% (N = 8) completely resolved, 35% (N = 7) improved or had residual ulceration attributed to disease, and 25% (N = 5) had ulceration related to toxicity. There were no carotid bleeding events (CBE) related to SBRT, however 10% (N = 2) experienced fatal CBE related to progressive disease at 2.3 mo and 6.7 mo from SBRT. The rate of grade ≥2 treatment related skin toxicity was 19% (N = 7) and only occurred in those with pre-SBRT SI/A. These included a grade 2 neck wound and tracheostomy infection, a grade 3 infection, and two grade 3 soft tissue necrosis. One patient had cellulitis/meningitis related to scalp radiation, and one had an untreated SBRT wound as they transitioned to hospice. Dysphagia requiring PEG occurred in 5% (N = 2), one of which was related to CNX palsy. Six patients (17%) had post-SBRT nerve impairment including one each of grade 2 facial nerve paralysis, grade 2 brachial plexopathy, grade 3 CNVIII dysfunction, grade 3 CNX impairment, and two patients with grade 2 CNXII impairment.

CONCLUSION

SBRT for locally recurrent previously radiated HNC can provide effective local control in a patient population at high risk of morbidity and mortality from local disease progression. In patients who have >180˚ CE or SI/A, we observed non-trivial toxicity, but disease progression may have been more morbid. For appropriately counseled patients with limited treatment options, CE or SI/A may not be an absolute contraindication to SBRT re-irradiation.

Local Cost-Effectiveness of Nasopharyngeal Carcinoma Screening Strategies in Southern China: Secondary Analysis of the PRO-NPC-001 Cluster-Randomized Trial

PURPOSE/OBJECTIVE(S)

Population-based screening for endemic nasopharyngeal carcinoma (NPC) detects most cases at an early stage. In a cluster-randomized trial conducted in Guangdong, a combination of Epstein-Barr Virus (EBV) anti-VCA/EBNA1 IgA serology and endoscopy reduced NPC mortality. We conducted a secondary analysis of this trial in conjunction with local incidence and cost data, hypothesizing that screening would be cost-effective in this region.

MATERIALS/METHODS

We estimated population-level NPC mortality reduction, resource utilization, and cost-effectiveness of 12 unique screening strategies in six populations in Guangdong/Guangxi using a previously-validated time-inhomogeneous decision-analytic cohort model. These 12 strategies evaluated combinations of serology, nasopharyngeal swab PCR (NP PCR), endoscopy, and head/neck MRI. Incidence data, screening costs, and healthcare costs were obtained from local cancer registries, laboratories conducting ELISA/PCR, and the Guangdong provincial healthcare system. We evaluated variable screening ages, sexes, intervals, and durations to identify optimal screening approaches from the perspective of the healthcare system in southern China. An incremental cost-effectiveness ratio (ICER) willingness-to-pay threshold of 1.50 times the per-capita GDP was considered cost-effective in southern China.

RESULTS

For the base strategy screening 50-year-old men and women using only serology and endoscopy, the average cost per screened subject for a single round of screening over a five-year cycle was ¥175.69. The addition of MRI improved sensitivity (76% vs. 62%) and approximately doubled screening costs. Triage with NP PCR was cost-neutral when used in conjunction with MRI and reduced endoscopy/MRI utilization by 37% with a 3-4% reduction in screening sensitivity. Among 50-year-old men and women, screening was cost-effective in all populations provided that medium-risk subjects were not referred for endoscopy/MRI (ICER/GDP 0.62-0.83). The use of NP PCR without MRI (ICER/GDP 0.83) was dominated by the base strategy (ICER/GDP 0.62) due to higher costs and NPC mortality. After a single five-year screening cycle, screening reduced population NPC mortality by 14% with serology + endoscopy and 21% with serology + endoscopy + MRI. Introduction of MRI with or without NP PCR could be cost-effective in all populations. For MRI-based strategies, the most efficient use of resources was deferral of endoscopy unless MRI was abnormal (ICER/GDP 0.67). Overall, the best-performing strategies balanced NPC mortality, screening costs, and MRI utilization.

CONCLUSION

EBV serology-based screening for endemic NPC is likely to be cost-effective among adult men and women in Guangdong and Guangxi. Referring medium-risk subjects for endoscopy/MRI should be avoided, and NP PCR should be used to triage individuals for MRI rather than endoscopy. These data may aid the design of population-based screening programs in this region.

Definitive Radiotherapy for the Treatment of Gross Disease in Unresected Differentiated Thyroid Cancer

PURPOSE/OBJECTIVE(S)

While surgery (with or without radioactive iodine (RAI)) is the mainstay of locoregional control in differentiated thyroid cancer (DTC), patients with unresectable disease present a clinical challenge. Uncontrolled disease in the neck can lead to substantial morbidity and mortality in DTC and obtaining locoregional control is vital to preserving quality of life and longevity. High dose definitive radiotherapy (RT) for gross disease in DTC is understudied. This study examines the efficacy of definitive RT in this setting.

MATERIALS/METHODS

From an IRB-approved registry of head and neck cancer cases treated at a tertiary care center over a period of 8 years (2014-2022), patients with incompletely resected or unresectable DTC including papillary, follicular, mixed, medullary, and poorly differentiated types were identified. All patients were treated to the neck and/or thyroid regions with visible gross disease to a definitive dose of radiation. The primary endpoint was local control within the radiated portal with a secondary endpoint of locoregional control within the neck.

RESULTS

A total of 31 patients were identified, of whom 74.2% were Caucasian. Fourteen were female (45.2%), and 17 (54.8%) were male. The median age was 68 years (range 26-90) and the median follow-up was 31 months. Histologically, 19 (61.3%) cases were papillary, 4 (12.9%) were follicular, 2 (6.5%) were mixed, 3 (9.7%) were medullary, and 3 (9.7%) were poorly differentiated. Among patients with non-medullary DTC 18 (69.2%) received prior RAI. Twelve patients were treated with radiation at initial diagnosis, while 19 patients were treated at the time of recurrence; two patients received concurrent chemotherapy. Twenty-eight patients (90.3%) were treated with IMRT and 3 (9.7%) were treated with SBRT. The median dose to the gross disease was 66 Gy (range 30-70.4) in 32 fractions (range 5-35). Overall, 5 patients (16.1%) experienced a locoregional failure after RT and all experienced failure in the RT portal. The actuarial infield control/locoregional control of radiation therapy at 3 and 5 years was 84.8% and 74.2%, respectively. Overall survival at 3 and 5 years was 68.5% and 47.4%, respectively. Among patients who had a locoregional failure after RT, 2 patients were salvaged with systemic therapy, 2 patients with surgery, and 1 patient with SBRT re-irradiation (40 Gy/5 fractions). The patient salvaged with SBRT remains without disease 8 months post-RT.

CONCLUSION

Definitive radiotherapy is a highly effective strategy to obtain durable control of unresected DTC. It should be standard for unresected disease and considered as a viable alternative for patients with borderline resectable disease for whom resection would be highly morbid.

Partial Tongue Sparing without Marginal Failures: The Dosimetric Advantages for Oral Tongue Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

Due to a lack of internal barriers, many radiation oncologists believe whole tongue (WT) irradiation is warranted in the adjuvant setting for oral tongue cancer. Our institutional practice is to include the resection bed and flap with a 5-10 mm margin, attempting to spare unaffected oral tongue. We hypothesize that partial tongue (PT) irradiation, when feasible, results in decreased dose to surrounding normal structures without an increased risk of local recurrence (LR).

MATERIALS/METHODS

Patients with a new diagnosis of squamous cell carcinoma of the oral tongue treated with adjuvant IMRT between 2010 and 2021 were collected from an IRB approved database. PT was defined as <80% of residual tongue in the clinical target volume (CTV). Recurrence was deemed local if in the tongue or floor of mouth, and in field if within the CTV or marginal if outside of CTV. Mean dose to mandible, pharyngeal constrictors, and oral cavity were evaluated. Comparisons between groups were made using parametric one-way ANOVA. Multivariable linear regression was used to predict mean radiation dose. Local control and overall survival were estimated using Kaplan-Meier.

RESULTS

A total of 130 patients are included with median follow up 34.1 months (IQR 13.5-64.6). Radiation dose was 48-72 Gy in 24-36 fractions, most commonly 60-66 Gy in 30-33 fractions (84.6%). All were treated to oral cavity, and neck irradiation included bilateral 96 (72%), unilateral 31 (24%), and none 3 (4%). PT sparing was feasible in 91 (70%) and 39 (30%) required WT. Primary tumor stage in PT included 20 pT1, 50 pT2, 17 pT3, and 4 pT4, and WT included 3 pT1, 8 pT2, 15 pT3, and 13 pT4. 3-year local control for PT and WT was 96% and 87%, respectively. LR occurred in 14 patients overall (10.8%), 6.6% (6) of patients treated with PT and 20.5% (8) treated with WT (p = 0.072). Of the LR for PT, stage was 2 pT1, 3 pT2, and 1 pT3, and all occurred within the radiation field. Of the LR for WT, stage was 1 each of pT1 and pT2, 2 pT3, and 4 pT4. Overall survival was 57%, regional and distant recurrence was each 17.7%. Dosimetric analysis for PT vs WT is described in Table 1, demonstrating lower mean dose when the primary tumor CTV is limited to PT. Unilateral neck irradiation also resulted in a lower mandible [-8.5 Gy (-11.2 - -5.8)], pharyngeal constrictor [-14.3 Gy (-18.1 - -10.5)], and oral cavity [-9.0 Gy (-13.0 - -5.0)] dose (all p<0.001).

CONCLUSION

Limiting the primary tumor CTV to PT for adjuvant radiotherapy resulted in significant sparing of the mandible and pharyngeal constrictors, and a routinely lower oral cavity mean dose of ≥3.5 Gy. There was a low risk of LR when implementing PT, and all LR occurred in field. Given the increased sparing of normal structures, and low risk of LR outside of PT radiation field, sparing a portion of unaffected oral tongue should be considered.

Phase II Randomized Trial of Single- vs. Two-Fraction Spine Stereotactic Radiosurgery for the Treatment of Vertebral Metastases

PURPOSE/OBJECTIVE(S)

As systemic therapies improve significantly, more patients with limited metastatic disease are undergoing spine stereotactic radiosurgery (sSRS). High dose (≥24 Gy) single fraction sSRS has been associated with a vertebral compression fracture (VCF) risk of up to 40%. Comparatively, lower dose (16-18 Gy) single fraction sSRS is associated with a fracture risk of 15-20%, with the risk increasing as the dose increases. To mitigate the risk of VCF, while optimizing higher dose delivery, some have advocated utilizing two-fraction sSRS regimen. Therefore, we designed a phase II randomized trial in which we hypothesized that single fraction sSRS is non-inferior to two-fraction sSRS with respect to VCF but offers patients greater convenience.

MATERIALS/METHODS

Inclusion criteria include age ≥18, Karnofsky performance score ≥70, vertebral metastasis from C3 to L5, maximum of three separate sites of metastases, limited paraspinal extension (<5 cm), and no rapid neurological decline. Patients must also be either Recursive Partitioning Analysis Class 1 (KPS >70 AND controlled systemic disease) or Class 2 (KPS >70, uncontrolled systemic disease OR KPS ≤70, age ≥54, no visceral metastases). Exclusion criteria include multiple primary cancers, primary neoplasm of the spine, prior surgery at the site of sSRS, spinal cord compression, bony retropulsion resulting in neurologic deficit, inability to undergo/contraindication to MRI, or diffuse multi-level metastatic spine disease. Our primary hypothesis is that single fraction sSRS (experimental arm - 16-18 Gy) is non-inferior to two fraction sSRS (standard arm - 24 Gy). Furthermore, we hypothesize that both treatment arms will have similar local control, pain control, quality of life and toxicity profiles. The primary endpoint of this trial is the development or progression of VCF at 6 months. Secondary endpoints include local control, pain control, quality of life and toxicity all of which will be assessed at 12 months. For the sample size calculation, we assumed a VCF risk of 17% in the experimental arm and a 7% risk in the standard arm. Based on these calculations, we aim to enroll 130 patients, 65 in each arm. This trial is currently enrolling patients actively, and approximately 30% of expected enrollment has been completed to date. This trial is registered on clinicaltrials.gov: NCT04218617.

RESULTS

Pending full accrual.

CONCLUSION

Pending full accrual.

Reimagining Drug Manufacturing Paradigm in Today’s Pharmacy Landscape

The coronavirus disease 2019 pandemic has escalated the ongoing problem of critical medication shortages, which has serious implications for the health of our patients. Currently, active pharmaceutical ingredients (APIs) are synthesized in large-scale batch operations and shipped to drug product manufacturers, where they are produced on a large scale at centralized facilities. In the centralized drug manufacturing process, the formulation components, operations, and packaging are structured to favor long-term storage and shipment of resultant medicines to the point of care, making this process vulnerable to supply chain disruptions. We propose a rethinking of the drug manufacturing paradigm with an upgraded pharmaceutical compounding-based manufacturing paradigm. This paradigm will be based on integration of continuous manufacturing of APIs and manufacturing of medicines at the point of care with application of machine learning, artificial intelligence, and 3-dimensional printing. This paradigm will support implementation of precision medicine and customization according to patients’ needs. The new model of drug manufacturing will be less dependent on the supply chain while ensuring availability of medicines in a cost-effective manner.

Saline groundwater in the Buffels River catchment, Namaqualand, South Africa: A new look at an old problem

Namaqualand, South Africa, is a global biodiversity hotspot but local populations are affected by challenging economic conditions largely because of poor access to water. In this study groundwater types are characterised and sources of salts and salinisation processes are identified using hydrochemistry and δ¹⁸O, δ²H and ⁸⁷Sr/⁸⁶Sr data. Analysis of δ¹⁸O and δ²H data suggests that evaporation does not play a major role in salinisation of the groundwater. However, major ion chemistry and ⁸⁷Sr/⁸⁶Sr ratios indicate that salts present in the groundwater are linked to dry deposition of marine aerosols and ion-exchange reactions in soils in the alluvial aquifer systems. The hydrochemical variability of the groundwater in the basement aquifer system suggests that there are strong local controls linked to weathering processes in individual basement rock types. The region is also notable for the high density of heuweltjies, biophysical features associated with increased nutrient levels, associated with termite activity. Electromagnetic scanning as well as measurement of water-soluble soil electrical conductivity values on and off heuweltjies, show that heuweltjies are saline with salinity increasing with depth. The level of groundwater salinity correlates with the level of heuweltjie salinity. Precipitation records from the last 150 years provide support for the hypothesis that accumulated salts, and in particular, heuweltjie salts are flushed into the groundwater system during sporadic large volume precipitation events. Thus, heuweltjies and hence termite activity, could potentially represent a previously unrecognized contributor to groundwater salinisation across Namaqualand and in other parts of the world.

Spatial and temporal variability of tritium in precipitation within South Africa and it's bearing on hydrological studies

Tritium, the radioactive isotope of hydrogen, has been used to understand groundwater recharge processes for decades. The current variation of tritium in the atmosphere is largely attributed to stratospheric production and fall out rates as well as global circulation phenomena controlling the hydrological cycle. Global controls on the variability in atmospheric tritium activity are poorly suited to explain local variation and tritium activities in precipitation are often assumed to be uniform over both local and regional catchments and watersheds. This assumption can result in both over and under estimation of modern recharge within an aquifer when using tritium as the recharge proxy. In order to minimize the inherent prediction residuals associated with tritium based recharge investigations, the variability of tritium in precipitation was modelled from 127 spatial precipitation samples taken over a two year period, combined with a 76 precipitation sample group-set taken over a one year period in a single location. Precipitation events were traced backward in time, from the point of collection, using HYSPLIT modelling to ascertain the origins of moisture content as well as the altitudes of moisture origin reached along the particle track. Tritium activities, collected over a one year period in Paarl, range from 0.45 to 4.16 TU and have a mean of 1.59 TU. Spatial storm events in the Western Cape in 2017 and 2018 had a range from 0 to 2.2 and 0.37 to 3.27 TU, respectively, with mean activities of 1.18 (n = 34) and 1.25 TU (n = 32). Both storm events had similar tritium variability (σ = 0.5 n = 35 and 0.48 n = 32). Regional precipitation events had the largest range of tritium activities (0.55-12.2 TU). Although not all tritium activities can be explained by interrogating the water mass origin, this study suggests that approximately 90% of events can be completely or partially attributed to the origin of the water mass. The variability of tritium, both spatially and temporally, was higher than expected, confirming that when uniform tritium inputs are used, the groundwater system would provide inaccurate modern recharge estimates. Higher spatial resolution of tritium variation in precipitation for a particular region will improve our ability to relate tritium activities in groundwater to local precipitation.

International multicentre review of perioperative management and outcome for catecholamine-producing tumours

BACKGROUND

Surgery for catecholamine-producing tumours can be complicated by intraoperative and postoperative haemodynamic instability. Several perioperative management strategies have emerged but none has been evaluated in randomized trials. To assess this issue, contemporary perioperative management and outcome data from 21 centres were collected.

METHODS

Twenty-one centres contributed outcome data from patients who had surgery for phaeochromocytoma and paraganglioma between 2000 and 2017. The data included the number of patients with and without α-receptor blockade, surgical and anaesthetic techniques, complications and perioperative mortality.

RESULTS

Across all centres, data were reported on 1860 patients with phaeochromocytoma or paraganglioma, of whom 343 underwent surgery without α-receptor blockade. The majority of operations (78·9 per cent) were performed using minimally invasive techniques, including 16·1 per cent adrenal cortex-sparing procedures. The cardiovascular complication rate was 5·0 per cent overall: 5·9 per cent (90 of 1517) in patients with preoperative α-receptor blockade and 0·9 per cent (3 of 343) among patients without α-receptor blockade. The mortality rate was 0·5 per cent overall (9 of 1860): 0·5 per cent (8 of 517) in pretreated and 0·3 per cent (1 of 343) in non-pretreated patients.

CONCLUSION

There is substantial variability in the perioperative management of catecholamine-producing tumours, yet the overall complication rate is low. Further studies are needed to better define the optimal management approach, and reappraisal of international perioperative guidelines appears desirable.

RNF168-Mediated Ubiquitin Signaling Inhibits the Viability of BRCA1-Null Cancers

BRCA1 gene mutations impair homologous recombination (HR) DNA repair, resulting in cellular senescence and embryonic lethality in mice. Therefore, BRCA1-deficient cancers require adaptations that prevent excessive genomic alterations from triggering cell death. RNF168-mediated ubiquitination of γH2AX at K13/15 (ub-H2AX) serves as a recruitment module for the localization of 53BP1 to DNA break sites. Here, we found multiple BRCA1-mutant cancer cell lines and primary tumors with low levels of RNF168 protein expression. Overexpression of ectopic RNF168 or a ub-H2AX fusion protein induced cell death and delayed BRCA1-mutant tumor formation. Cell death resulted from the recruitment of 53BP1 to DNA break sites and inhibition of DNA end resection. Strikingly, reintroduction of BRCA1 or 53BP1 depletion restored HR and rescued the ability of cells to maintain RNF168 and ub-H2AX overexpression. Thus, downregulation of RNF168 protein expression is a mechanism for providing BRCA1-null cancer cell lines with a residual level of HR that is essential for viability. Overall, our work identifies loss of RNF168 ubiquitin signaling as a proteomic alteration that supports BRCA1-mutant carcinogenesis. We propose that restoring RNF168-ub-H2AX signaling, potentially through inhibition of deubiquitinases, could represent a new therapeutic approach. SIGNIFICANCE: This study explores the concept that homologous recombination DNA repair is not an all-or-nothing concept, but a spectrum, and that where a tumor stands on this spectrum may have therapeutic relevance.See related commentary by Wang and Wulf, p. 2720.

Specific Programmed Multiple Development–Thin Layer Chromatography of Furazolidone in Chicken, Turkey, Swine, and Bovine Tissues: Collaborative Study

A specific method for assay of furazolidone at 2 ppb has been developed using programmed multiple development-thin layer chromatography (PMD-TLC) and the conversion of the drug to a fluorescent species which is quantitated by fluorodensitometry on the TLC plate. The method requires only 5 g tissue, specifies an automatic spotter for PMD-TLC, and is capable of measuring &lt;1 ng of drug when the fluorodensitometer is coupled with a computing integrator. This procedure requires an average of 2 man-hours per sample and can be completed in one day. Six laboratories collaboratively studied the method for assay of furazolidone at the 2, 3, and 6 ppb levels in chicken, turkey, swine, and bovine tissues. Tissues were fortified by each laboratory and then processed through extraction, solvent partition, programmed multiple development-thin layer chromatography, and fluorodensitometry. Results showed satisfactory recoveries and accuracy. A statistical comparison of the results demonstrated that 5 of the 6 laboratories obtained similar results. The higher responses from the sixth laboratory appeared to be due to an exceptional vacuum system and the use of silated flasks. The mean drug recovery response for the tissues spiked at 2 ppb from the 5 laboratories was 2.2324 ng ± 20.2% (SD), which at the 99.7% confidence level gives no overlap with control tissue data. The results can be expected to be repeatable within and among laboratories.

Trait-based characterization of species transported on Japanese tsunami marine debris: Effect of prior invasion history on trait distribution

Nearly 300 coastal marine species collected from >630 debris items from the 2011 Great East Japan earthquake and tsunami have landed alive along the North American Pacific coast and the Hawaiian Archipelago. We synthesized life history, environmental, and distributional traits for 103 of these species and compared species with (n=30) and without (n=62) known invasion histories. The species represent 12 phyla, and Mollusca, Crustacea, and Bryozoa accounted for 71 of the 103 species. The majority are native to the Northwest Pacific and the Central Indo-Pacific. Species with known invasion history were more common on artificial and hardpan substrates, in temperate reef, fouling, and flotsam habitats, at subtropical and tropical temperatures, and exhibited greater salinity tolerance than species with no prior invasion history. Thirty-five Japanese tsunami marine species without prior invasion history overlapped in ordination trait space with known invaders, indicating a subset of species in this novel assemblage that possess traits similar to species with known invasion history.

Transoceanic dispersal of the mussel Mytilus galloprovincialis on Japanese tsunami marine debris: An approach for evaluating rafting of a coastal species at sea

Biofouled debris from the 2011 Great East Japan earthquake and tsunami has landed in the Northeast Pacific and along the Hawaiian Islands since 2012. As of 2017, >630 biofouled debris items with >320 living species of algae, invertebrates, and fish have been examined. The invasive mussel Mytilus galloprovincialis was present on >50% of those items. Size, reproduction, and growth of this filter-feeding species were examined to better understand long-distance rafting of a coastal species. The majority of mussels (79%) had developing or mature gametes, and growth rates averaged 0.075±0.018 SE mm/day. Structural and elemental (barium/calcium) analysis of mussel shells generated estimates of growth in coastal waters (mean=1.3 to 25mm total length), which provides an indication of residence times in waters along North America and the Hawaiian Islands prior to landing. Detailed studies of individual species contribute to our understanding of debris as a transport vector and aid efforts to evaluate potential risks associated with marine debris.

Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography

The 2011 East Japan earthquake generated a massive tsunami that launched an extraordinary transoceanic biological rafting event with no known historical precedent. We document 289 living Japanese coastal marine species from 16 phyla transported over 6 years on objects that traveled thousands of kilometers across the Pacific Ocean to the shores of North America and Hawai‘i. Most of this dispersal occurred on nonbiodegradable objects, resulting in the longest documented transoceanic survival and dispersal of coastal species by rafting. Expanding shoreline infrastructure has increased global sources of plastic materials available for biotic colonization and also interacts with climate change–induced storms of increasing severity to eject debris into the oceans. In turn, increased ocean rafting may intensify species invasions.

Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties

This paper investigates the effects of moisture, anisotropy, stress state, and strain rate on the mechanical properties of the bighorn sheep (Ovis Canadensis) horn keratin. The horns consist of fibrous keratin tubules extending along the length of the horn and are contained within an amorphous keratin matrix. Samples were tested in the rehydrated (35wt% water) and ambient dry (10wt% water) conditions along the longitudinal and radial directions under tension and compression. Increased moisture content was found to increase ductility and decrease strength, as well as alter the stress state dependent nature of the material. The horn keratin demonstrates a significant strain rate dependence in both tension and compression, and also showed increased energy absorption in the hydrated condition at high strain rates when compared to quasi-static data, with increases of 114% in tension and 192% in compression. Compressive failure occurred by lamellar buckling in the longitudinal orientation followed by shear delamination. Tensile failure in the longitudinal orientation occurred by lamellar delamination combined with tubule pullout and fracture. The structure-property relationships quantified here for bighorn sheep horn keratin can be used to help validate finite element simulations of ram's impacting each other as well as being useful for other analysis regarding horn keratin on other animals.

STATEMENT OF SIGNIFICANCE

The horn of the bighorn sheep is an anisotropic composite composed of keratin that is highly sensitive to moisture content. Keratin is also found in many other animals in the form of hooves, claws, beaks, and feathers. Only one previous study contains high rate experimental data, which was performed in the dry condition and only in compression. Considering the bighorn sheep horns' protective role in high speed impacts along with the moisture and strain rate sensitivity, more high strain rate data is needed to fully characterize and model the material. This study provides high strain rate results demonstrating the effects of moisture, anisotropy, and stress state. As a result, the comprehensive data allows modeling efforts to be greatly improved.

Plasma metabolomic profiles of breast cancer patients after short-term limonene intervention

Limonene is a lipophilic monoterpene found in high levels in citrus peel. Limonene demonstrates anticancer properties in preclinical models with effects on multiple cellular targets at varying potency. While of interest as a cancer chemopreventive, the biologic activity of limonene in humans is poorly understood. We conducted metabolite profiling in 39 paired (pre/postintervention) plasma samples from early-stage breast cancer patients receiving limonene treatment (2 g QD) before surgical resection of their tumor. Metabolite profiling was conducted using ultra-performance liquid chromatography coupled to a linear trap quadrupole system and gas chromatography-mass spectrometry. Metabolites were identified by comparison of ion features in samples to a standard reference library. Pathway-based interpretation was conducted using the human metabolome database and the MetaCyc database. Of the 397 named metabolites identified, 72 changed significantly with limonene intervention. Class-based changes included significant decreases in adrenal steroids (P < 0.01), and significant increases in bile acids (P ≤ 0.05) and multiple collagen breakdown products (P < 0.001). The pattern of changes also suggested alterations in glucose metabolism. There were 47 metabolites whose change with intervention was significantly correlated to a decrease in cyclin D1, a cell-cycle regulatory protein, in patient tumor tissues (P ≤ 0.05). Here, oral administration of limonene resulted in significant changes in several metabolic pathways. Furthermore, pathway-based changes were related to the change in tissue level cyclin D1 expression. Future controlled clinical trials with limonene are necessary to determine the potential role and mechanisms of limonene in the breast cancer prevention setting.

Metabolomic characterization of nipple aspirate fluid by (1)H NMR spectroscopy and GC-MS

Nipple aspirate fluid (NAF) is a noninvasively obtained biofluid from the duct openings of the breast. NAF components are constantly secreted, metabolized, and reabsorbed by the epithelial lining of the lactiferous ducts of the breast. NAF has been studied as a potential breast tissue surrogate for the discovery of novel breast cancer risk, early detection, and treatment response biomarkers. We report the first unsupervised metabolite characterization of nipple aspirate fluid using NMR and GC-MS using convenience samples previously collected from four premenopausal and four postmenopausal women. A total of 38 metabolites were identified using the two analytical techniques, including amino acids, organic acids, fatty acids, and carbohydrates. Analytical reproducibility of metabolites in NAF by GC-MS was high across different extraction and analysis days. Overall, 31 metabolites had a coefficient of variation below 20%. By GC-MS, there were eight metabolites unique to NAF, 19 unique to plasma, and 24 shared metabolites. Correlative analysis of shared metabolites between matched NAF and plasma samples from pre- and postmenopausal women shows almost no correlations, with the exception being lactic acid, which was significantly negatively correlated (R(2) = 0.57; P = 0.03). These results suggest that NAF is metabolically distinct from plasma and that the application of metabolomic strategies may be useful for future studies investigating breast cancer risk and intervention response biomarkers.

Elemental markers in elasmobranchs: effects of environmental history and growth on vertebral chemistry

Differences in the chemical composition of calcified skeletal structures (e.g. shells, otoliths) have proven useful for reconstructing the environmental history of many marine species. However, the extent to which ambient environmental conditions can be inferred from the elemental signatures within the vertebrae of elasmobranchs (sharks, skates, rays) has not been evaluated. To assess the relationship between water and vertebral elemental composition, we conducted two laboratory studies using round stingrays, Urobatis halleri, as a model species. First, we examined the effects of temperature (16°, 18°, 24°C) on vertebral elemental incorporation (Li/Ca, Mg/Ca, Mn/Ca, Zn/Ca, Sr/Ca, Ba/Ca). Second, we tested the relationship between water and subsequent vertebral elemental composition by manipulating dissolved barium concentrations (1x, 3x, 6x). We also evaluated the influence of natural variation in growth rate on elemental incorporation for both experiments. Finally, we examined the accuracy of classifying individuals to known environmental histories (temperature and barium treatments) using vertebral elemental composition. Temperature had strong, negative effects on the uptake of magnesium (D_Mg) and barium (D_Ba) and positively influenced manganese (D_Mn) incorporation. Temperature-dependent responses were not observed for lithium and strontium. Vertebral Ba/Ca was positively correlated with ambient Ba/Ca. Partition coefficients (D_Ba) revealed increased discrimination of barium in response to increased dissolved barium concentrations. There were no significant relationships between elemental incorporation and somatic growth or vertebral precipitation rates for any elements except Zn. Relationships between somatic growth rate and D_Zn were, however, inconsistent and inconclusive. Variation in the vertebral elemental signatures of U. halleri reliably distinguished individual rays from each treatment based on temperature (85%) and Ba exposure (96%) history. These results support the assumption that vertebral elemental composition reflects the environmental conditions during deposition and validates the use of vertebral elemental signatures as natural markers in an elasmobranch. Vertebral elemental analysis is a promising tool for the study of elasmobranch population structure, movement, and habitat use.

Abstract 160: Modulation of the serum metabolomic profiles of breast cancer patients after receiving limonene intervention

Background. Limonene is a bioactive food component found in citrus peel oil that has demonstrated chemopreventive and chemotherapeutic activities in preclinical studies. To better characterize its mechanism of action in the clinical setting, we measured the serum metabolomic profiles of breast cancer patients before and after receiving a short-term limonene intervention.

Methods. Forty women with stage 0 - II breast cancer received 2 g QD limonene daily for 2 - 6 weeks (21.5 ± 8.8 days) before surgical resection of their tumor. Pre/post intervention blood draws were taken to assess serum metabolomic profiles. Metabolomic analysis was performed on the gas chromatography mass spectrometry and liquid chromatography mass spectrometry platforms established at Metabolon, Inc.

Results. Of the 397 identified biochemicals, 71 changed significantly (p&lt;0.05) from baseline to post limonene intervention. Pathway analysis revealed several key metabolic changes. Significant increases were noted in eight bile acid conjugates following limonene intervention, including a 3-fold elevation in taurocholate, taurodeoxycholate, and glycoursodeoxycholate. There were also significant decreases in a number of steroid hormones including dehydroisoandrosterone sulfate (DHEA-S), 4-androsten-3beta, 17beta-diol disulfate, epiandrosterone sulfate, androsterone sulfate, and pregnen-diol disulfate. In addition, markers of collagen remodeling or degradation were elevated following limonene intervention. Increased circulating vitamin C, improved insulin sensitivity and glycemic control, and reduced inflammatory potential were also noted following limonene treatment. An increase in plasma levels of ten different glycerophosphocholines and four carnitines were all significantly correlated to a decrease in cyclinD1 (all p's&lt;0.01 and Rˆ2&gt;0.4) in an exploratory analysis.

Conclusions. This global metabolomic profiling study revealed several novel mechanistic insights into the potential clinical activities of limonene. Efforts are ongoing to correlate these metabolic changes to carcinogenesis, clinical characteristics, and risk markers measured in breast tissue and serum.

Citation Format: Jessica A. Miller, Kirk Pappan, Chengcheng Hu, Elizabeth J. Want, Hector Keun, Julie E. Lang, H-H Sherry Chow. Modulation of the serum metabolomic profiles of breast cancer patients after receiving limonene intervention. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 160. doi:10.1158/1538-7445.AM2013-160

Expression of epidermal growth factor, transforming growth factor-β1 and adiponectin in nipple aspirate fluid and plasma of pre and post-menopausal women

BACKGROUND

Nipple aspirate fluid (NAF) contains large amounts of protein thought to reflect the microenvironment of the breast, and is of interest in breast cancer prevention research. The correlation between specific NAF proteins to plasma concentrations have not been well studied in healthy women. We collected matched NAF and plasma from 43 healthy pre and postmenopausal women participating in an early phase clinical study to compare the levels of putative cancer protein biomarkers. We compared baseline NAF and plasma levels of epidermal growth factor (EGF), transforming growth factor-beta 1 (TGF-β1), and adiponectin and evaluated menopausal status and body mass index (BMI) as potential modifying factors.

FINDINGS

NAF and plasma levels of EGF, TGF-β1 and adiponectin were not correlated. EGF and TGF-β1 levels in NAF of premenopausal women were significantly higher than postmenopausal women (P's < 0.01). These differences by menopausal status were not observed in plasma. Both NAF and plasma adiponectin levels were non-significantly higher in postmenopausal women. NAF biomarker levels were not associated with BMI whereas plasma EGF, TGF-β1 and adiponectin levels in postmenopausal women were all inversely correlated with BMI (P's < 0.05).

CONCLUSIONS

Protein biomarkers differ significantly between NAF and plasma and are affected differently by both BMI and menopausal status. This study demonstrates important differences in biological information gained by characterizing biomarkers in NAF compared to plasma and suggests each sample source may independently inform on breast cancer risk.

Human breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer

Limonene is a bioactive food component found in citrus peel oil that has shown chemopreventive and chemotherapeutic activities in preclinical studies. We conducted an open-label pilot clinical study to determine the human breast tissue disposition of limonene and its associated bioactivity. We recruited 43 women with newly diagnosed operable breast cancer electing to undergo surgical excision to take 2 grams of limonene daily for two to six weeks before surgery. Blood and breast tissue were collected to determine drug/metabolite concentrations and limonene-induced changes in systemic and tissue biomarkers of breast cancer risk or carcinogenesis. Limonene was found to preferentially concentrate in the breast tissue, reaching high tissue concentration (mean = 41.3 μg/g tissue), whereas the major active circulating metabolite, perillic acid, did not concentrate in the breast tissue. Limonene intervention resulted in a 22% reduction in cyclin D1 expression (P = 0.002) in tumor tissue but minimal changes in tissue Ki67 and cleaved caspase-3 expression. No significant changes in serum leptin, adiponectin, TGF-β1, insulin-like growth factor binding protein-3 (IGFBP-3), and interleukin-6 (IL-6) levels were observed following limonene intervention. There was a small but statistically significant postintervention increase in insulin-like growth factor I (IGF-I) levels. We conclude that limonene distributed extensively to human breast tissue and reduced breast tumor cyclin D1 expression that may lead to cell-cycle arrest and reduced cell proliferation. Furthermore, placebo-controlled clinical trials and translational research are warranted to establish limonene's role for breast cancer prevention or treatment.

Efficacy of amitraz-impregnated collars on white-tailed deer (Artiodactyla: Cervidae) in reducing free-living populations of lone star ticks (Acari: Ixodidae)

Over a 7 yr period, we monitored the effect of a commercially available, amitraz impregnated anti-tick collar in controlling free-living populations of lone star ticks, Amblyomma americanum (L.) when manually fitted around necks of white-tailed deer, Odocoileus virginianus (Zimmermann). Study animals in treatment and control groups were confined in 38.8 ha game-fenced and densely vegetated treatment plots in South Texas. Tick densities during years 1 and 7 served as untreated pre- and posttreatment comparisons and treatments occurred during years 2 through 5. Reductions in tick densities in the treatment plot were compared against tick densities in a control plot having similar vegetation and numbers of untreated deer. During years of treatment, indices of control pressure ranged from 18.2 to 82.6 for nymphs and 16.9-78.7 for adults, and efficacy, expressed as percentage control during the final year of treatment, was 77.2 and 85.0%, respectively, for nymphal and adult ticks. These data show that acaricidal collar treatments provide efficacies very similar to those achieved with the existing ivermectin-medicated bait and '4-Poster' topical treatment technologies to control ticks feeding on wild white-tailed deer.

Efficacy of AR-R15896AR in the rat monofilament model of transient middle cerebral artery occlusion

The monofilament technique of transient middle cerebral artery occlusion (MCAO) was used in 3 separate studies to evaluate the efficacy of the low-affinity, use-dependent N-methyl-d-aspartate receptor antagonist, AR-R15896AR. First, a dose-response curve was attempted. Wister Kyoto rats received 2 hours of MCAO. Five minutes later, a 30-minute intravenous infusion of AR-R15896AR was given, followed by subcutaneous implantation of Alzet minipumps that were calibrated to maintain specified plasma levels (approximately 682, 1885, or 2682 ng/mL) of AR-R15896 (free base) for 1 week. The highest plasma level attained significantly decreased the percentage of damage to the subcortex, cortex, and total brain. Second, the high-dose, 1-week treatment regimen was repeated to determine if neuroprotection would extend to 8 weeks after MCAO. Indeed, in separate groups of animals, significant reduction in the percentage of damage, which was generally confined to the cortex and subcortex, was observed at 1, 2, 4, and 8 weeks. Third, verification was achieved in another laboratory. Lister Hooded rats received 60 minutes of transient MCAO. At 70 minutes, an acute dose of AR-R15896AR (20.3 mg/kg) was injected intraperitoneally and the rats were killed 23 hours later. This treatment group also exhibited significant reduction in the volume of infarction in the subcortex, cortex, and total brain. The outcome of these investigations supports the ongoing Phase II clinical trials in patients with acute stroke.

Multimodal hyperspectral imaging for the noninvasive diagnosis of cervical neoplasia

OBJECTIVE

To determine the ability of Multimodal Hyperspectral Imaging (MHI) to noninvasively detect, localize and diagnose cervical neoplasia.

MATERIALS AND METHODS

The cervical epithelium was interrogated by MHI using tissue fluorescence and reflectance measurements after the probe was placed on the ectocervix. A Papanicolaou smear was taken, and a colposcopic examination was performed and cervical histologic specimens were collected, when indicated. MHI and Pap smear sensitivity and specificity data were compared with colposcopic and histologic results.

RESULTS

Nineteen patients had CIN2 or higher, 30 had CIN1, 34 had benign cellular changes or metaplasia, and 28 were normal by both Pap smear and colposcopic examination. At equal specificity (70%) for both tests, the sensitivity of MHI was 97%, compared to 72% for the Pap smear.

CONCLUSION

MHI detected cervical cancer precursors at a rate greater than that obtained by a simultaneously collected Pap smear.

Abstract 3560: Application of metabolomics to assess serum profiles in limonene-treated breast cancer patients

Background. Limonene is a highly lipophilic monoterpene found in citrus peel that has demonstrated anticancer effects in preclinical models. Limonene likely affects multiple targets with varying potency. Advanced techniques to obtain metabolomic profiles from biofluids have the potential to provide a non-invasive means to assess these multiple effects. This strategy was applied to a clinical trial with women with early stage breast cancer receiving limonene treatment. Methods. Forty women with stage 0 - 2 breast cancer received 2 g QD limonene daily for 2 - 6 weeks (21.5 + 8.8 days) before scheduled surgical resection of their tumor. Pre/post intervention blood draws were taken for metabolomics analysis. Metabolomics profiling was conducted using ultra performance liquid chromatography tandem time-of-flight mass spectrometry (UPLC-QToF). Chromatographic separation was achieved using a gradient of two mobile phases; A: 0.1% formic acid in water, and B: 0.1% formic acid in methanol with a flow rate of 0.4 mL/min. A Waters Aquity UltraPerformance LC HSS T3 column was used. Metabolomics data was preprocessed with XCMS. Preliminary metabolite identification was conducted by mining the Human Metabolome Database (HMDB). Results. Over 1,000 metabolite features were identified by metabolomic profiling. In negative ion mode, three metabolites exhibited a 48-fold change or higher from pre to post-intervention; 183.1 m/z at 9.4 min, 177.0 m/z at 10.0 min, and 345.1 m/z 8.9 min (P's&lt;0.001). Two distinct peaks with m/z of 103.0 elute at 1.9 and 2.25 minutes respectively and changed &gt;20% (P's&lt;0.05). Twenty potential metabolites were identified in positive ion mode with &gt;20% change by the intervention (P's&lt; 0.05), of these, two exhibited 10-fold change or higher; 312.2 m/z at 8.7 min, and 369.2 m/z at 9.0 min (P's&lt;0.001). Discussion. This study demonstrates that 2 g QD daily oral limonene results in significant changes in approximately 20 metabolites in serum. Candidate compounds include limonene metabolites, carnitines and end products of arachindonic acid metabolism. Efforts are ongoing to identify these metabolites for analyte specific verification and quantitation. Further clinical trials with limonene are necessary to establish its potential role as a chemopreventive agent in breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3560. doi:1538-7445.AM2012-3560

Abstract 3558: A pilot clinical study of limonene in women with early stage breast cancer: Effects of short-term treatment on tissue limonene disposition and serum markers

Background: Limonene is a highly lipophilic monoterpene found in citrus peel oil that has demonstrated anticancer properties in preclinical studies. The purpose of this study was to evaluate whether limonene and its primary metabolite perillic acid (PA) would distribute extensively to the breast tissue and reach an effective drug concentration. Secondary endpoints included evaluation of changes in cancer-related biomarkers in plasma and tissue. Methods: Participants (N = 40) with newly diagnosed stage 0 - 2 breast cancer took 2 grams daily of oral limonene for 2 - 6 weeks (21.5 ± 8.8 days) prior to planned surgical tumor resection. Blood was drawn pre/post intervention for measurement of serum concentration of limonene, PA, and protein biomarkers, as well as to assess toxicity profiles. A small piece of breast tissue adjacent to the tumor mass was also collected for analysis of limonene and PA levels. Limonene and PA levels in tissue and serum were analyzed using specific chromatography-based assays. Results: Limonene was found to preferentially concentrate in breast tissue (332.3 + 336.1 uM) versus plasma (0.49 + 0.67 uM) with tissue-to-plasma concentration ratio (TPCR) of 1,667 + 312.5 (P&lt;0.001). PA did not concentrate in breast tissue (5.73 + 10.28 uM) versus plasma (3.89 + 6.81 uM) with TPCR of 1.4 + 0.56. Post-intervention serum levels of leptin, adiponectin, TGF-beta1, IGFBP-3 and IL-6 were unchanged from baseline. There was a small but statistically significant post-intervention increase in IGF-1, however the change was no longer significant after adjustment for number of days on agent. Possibly or probably related adverse events were primarily GI-related and were not dose-limiting. No clinically significant changes in complete blood count, renal, hepatic or other blood chemistry studies were noted. Analysis of the intervention effects on tissue biomarkers of proliferation, apoptosis, and cell cycle regulation is ongoing. Discussion: Oral limonene preferentially concentrates in the breast tissue and has a favorable side effect profile. PA does not readily concentrate in breast tissue when administered as oral limonene. Short-term limonene intervention resulted in minimal changes in systemic biomarkers. Further clinical trials with a longer intervention are necessary to establish limonene's potential role as a chemopreventive agent in breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3558. doi:1538-7445.AM2012-3558

Safety and Feasibility of Topical Application of Limonene as a Massage Oil to the Breast

BACKGROUND

Limonene, a major component in citrus oil, has demonstrated anti-cancer effects in preclinical mammary cancer models. However, the effective oral dose translates to a human dose that may not be feasible for chronic dosing. We proposed to evaluate topical application of limonene to the breast as an alternative dosing strategy.

MATERIALS AND METHODS

We conducted a mouse disposition study to determine whether limonene would be bio available in the mammary tissue after topical application. SKH-1 mice received topical or oral administration of limonene in the form of orange oil every day for 4 weeks. Plasma and mammary pads were collected 4 hrs after the final dosing. We also conducted an exploratory clinical study to evaluate the safety and feasibility of topically applied limonene in the form of orange oil to the breast. Healthy women were recruited to apply orange oil containing massage oil to their breasts daily for four weeks. Safety and feasibility were assessed by reported adverse events, clinical labs, and usage compliance. Pre and post-intervention nipple aspirate fluid (NAF) and plasma were collected for limonene concentration determination.

RESULTS

The mouse disposition study showed that topical and oral orange oil administration resulted in similar mammary tissue disposition of limonene with no clinical signs of toxicity. In the clinical study, the topical application of limonene containing massage oil to the breast was found to be safe with high levels of usage compliance for daily application, although NAF and plasma limonene concentrations were not significantly changed after the massage oil application.

CONCLUSIONS

Our studies showed that limonene is bio available in mammary tissue after topical orange oil application in mice and this novel route of administration to the breast is safe and feasible in healthy women.

P3-11-03: A Phase I Trial of D-Limonene in Newly Diagnosed Breast Cancer Patients: A Chemoprevention Study

Background: D-limonene (DL) is a highly lipophilic monoterpene found naturally in citrus that has been demonstrated in preclinical studies to have anticancer properties. Early phase clinical trials support the investigation of DL in the chemoprevention of breast cancer. We sought to evaluate whether DL and its presumed active metabolite perillic acid (PA) would distribute extensively to the breast tissue and reach an effective drug concentration. We hypothesized that the mechanism of DL is related to the induction of apoptosis in cancer cells.

Materials and Methods: We enrolled 40 patients with newly diagnosed Stage 0–2 breast cancer to take 2 grams daily of oral DL for 2–6 weeks prior to planned surgical intervention. Blood was drawn pre/post intervention to assess for toxicity and plasma concentration of DL and PA. Adverse effects related or possibly related to the study drug were noted. A small piece of breast tissue adjacent to the tumor mass was used to measure drug concentration for each patient. DL and PA levels in breast tissue were analyzed by gas chromatography and liquid chromatography, respectively, in tandem with mass spectrometry. Analysis of variance testing was used to determine if DL or PA preferentially concentrated in the breast tissue compared to plasma. We tested for a possible modulation of the biomarkers estrogen receptor (ER), progesterone receptor, HER2, Ki67 or grade pre/post treatment by comparing results from the core biopsy to the surgical pathology and applying pairwise Student's T tests. The caspase 3 and the annexin V assays were performed by plating 10,000 cells per well for the cell lines MCF7, MDA-231, BT474, and T47D and separately administering DL and PA acid in serial dilutions in their treatment concentration ranges in triplicate and read by microplate. Results: DL was found to preferentially concentrate in breast tissue versus plasma (tissue/plasma concentration ratio (TPCR) of 1297, p&lt;0.001) while PA did not concentrate (TPCR of 1.4, p=0.9). 20 patients (50%) reported Grade 1 eructation, which was the most common adverse effect. A slight decrease in white count from a mean of 7.1 to 6.6 (p=0.03) and a slight increase in ALT from a mean of 22.5 to 26.9 (p=0.03) were noted. No other statistically significant changes in laboratory values related to serum complete blood count, renal, hepatic or other studies were noted. No change in tissue biomarkers were noted post-treatment. DL produced a dose dependent increase in the apoptotic markers cleaved caspase 3 and annexin V for the ER positive cell lines MCF7, BT474, and T47D, however, no such response was noted for the triple negative cell line MDA-231. A PA dose response trend was noted with the annexin V but not the caspase 3 assay for each cell line.

Discussion: D-limonene preferentially concentrates in the breast tissue and is a candidate chemopreventive agent based on its favorable side effect profile. PA does not readily concentrate in the breast when administered as oral DL. Our correlative studies establish that DL induces apoptosis in ER positive breast cancer cell lines; no definite relationship between PA and apoptosis was found. Further clinical trials of DL are necessary to establish its potential role as a chemopreventive agent in breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-11-03.

d-Limonene: a bioactive food component from citrus and evidence for a potential role in breast cancer prevention and treatment

Although limited, observations from cell culture, animal, and epidemiological studies support the presence of anti-cancer properties in citrus peel and the primary bioactive food constituent, d-limonene. Early evidence from animal models suggests that when ingested, d-limonene exhibits a wide spectrum of biologic activity including chemotherapeutic and chemopreventive effects. In some of these early models, an analog of d-limonene, perillyl alcohol, demonstrated a more potent effect than d-limonene itself. Yet, when perillyl alcohol advanced to clinical trials, several trials were ended early due to doselimiting toxicities. Alternatively, oral d-limonene administration in humans is well tolerated even at high doses supporting its investigation as a potential bioactive for cancer prevention. Though the exact mechanisms of action of d-limonene are unclear, immune modulation and antiproliferative effects are commonly reported. Here, we review the pre-clinical evidence for d-limonene’s anticancer mechanisms, bioavailability, and safety, as well as the evidence for anti-cancer effects in humans, focusing on studies relevant to its use in the prevention and treatment of breast cancer.

Adipose tissue accumulation of d-limonene with the consumption of a lemonade preparation rich in d-limonene content

d-limonene is a bioactive food component found in high concentration in citrus peel oil with anticancer effects in preclinical studies of mammary carcinogenesis. Extrapolation of preclinical data to human cancer is limited, in part, by inadequate information on the oral bioavailability and tissue disposition of d-limonene in humans. As a fat-soluble compound, d-limonene is more likely to deposit in fatty tissues such as the breast. To assess disposition of d-limonene in humans, we conducted a pilot study of oral d-limonene-rich lemonade. Following a 1-wk washout period devoid of citrus, healthy adults consumed 40 oz. of freshly prepared lemonade containing 500 to 600 mg d-limonene daily for 4 wk. On the first and last consumption days, blood and buttock fat biopsy were collected. Matched preintervention and postintervention fat biopsies (n = 7), and matched preintervention and postintervention plasma samples (n = 6), were analyzed for d-limonene levels using gas chromatography and mass spectrometry. There was a significant increase in d-limonene levels in the fat biopsies after 4 wk (P = 0.009); initial levels ranged from nondetectable to 7.79 micromol/kg tissue, and postintervention levels ranged from 53.6 to 294 micromol/kg tissue. Plasma d-limonene levels increased from 0.35 to 0.72 micromol/l initially to postintervention levels of 0.54 to 1.65 micromol/l (P = 0.016). Postintervention adipose d-limonene levels were 51.0 to 195 times higher than plasma levels (P = 0.009). Our results demonstrate accumulation of d-limonene in adipose tissue after oral dosing and support additional studies of d-limonene for chemoprevention in tissues such as the breast that are comprised of a significant fat fraction.

Resveratrol modulates drug- and carcinogen-metabolizing enzymes in a healthy volunteer study

Resveratrol has been shown to exhibit cancer-preventive activities in preclinical studies. We conducted a clinical study to determine the effect of pharmacologic doses of resveratrol on drug- and carcinogen-metabolizing enzymes. Forty-two healthy volunteers underwent baseline assessment of cytochrome P450 (CYP) and phase II detoxification enzymes. CYP1A2, CYP2D6, CYP2C9, and CYP3A4 enzyme activities were measured by the metabolism of caffeine, dextromethorphan, losartan, and buspirone, respectively. Blood lymphocyte glutathione S-transferase (GST) activity and GST-pi level and serum total and direct bilirubin, a surrogate for UDP-glucuronosyl transferase (UGT) 1A1 activity, were measured to assess phase II enzymes. After the baseline evaluation, study participants took 1 g of resveratrol once daily for 4 weeks. Enzyme assessment was repeated upon intervention completion. Resveratrol intervention was found to inhibit the phenotypic indices of CYP3A4, CYP2D6, and CYP2C9 and to induce the phenotypic index of 1A2. Overall, GST and UGT1A1 activities were minimally affected by the intervention, although an induction of GST-pi level and UGT1A1 activity was observed in individuals with low baseline enzyme level/activity. We conclude that resveratrol can modulate enzyme systems involved in carcinogen activation and detoxification, which may be one mechanism by which resveratrol inhibits carcinogenesis. However, pharmacologic doses of resveratrol could potentially lead to increased adverse drug reactions or altered drug efficacy due to inhibition or induction of certain CYPs. Further clinical development of resveratrol for cancer prevention should consider evaluation of lower doses of resveratrol to minimize adverse metabolic drug interactions.

THE EFFECTS OF EXPOSURE TO COLD UPON EXPERIMENTAL INFECTION OF THE RESPIRATORY TRACT

1. Respiratory infection of rabbits with Bacillus bovisepticus (snuffles) is favored by chilling the animals after they have been accustomed to heat. 2. The character of this disease, which occurs frequently in rabbits under natural conditions, makes the application of the experimental results to similar respiratory conditions in man less open to objection than in similar experiments with other infections. 3. The weight of experimental evidence, including our own, does not justify the elimination of exposure to cold as a possible though secondary factor in the incidence of acute respiratory disease. 4. From the limited data of our last two experiments it is suggested that any marked change of temperature predisposes rabbits to this infection, the severity of which varies with the amount of change, and that a change from low to high temperature has an even more marked effect than that from high to low.

Abstract A57: High-dose resveratrol modulates drug and carcinogen metabolizing enzymes in a healthy volunteer study

Purpose: Resveratrol (RES) or 3, 4′, 5-trihydroxystilbene has been shown to inhibit carcinogenesis by affecting various molecular events in the initiation, promotion and progression stages. The cancer chemopreventive activity of RES has been demonstrated in vivo in a wide variety of tumors including skin, mammary, gastrointestinal, and liver cancer models. Modulation of Phase I and Phase II enzymes has been suggested to be one of the mechanisms responsible for the cancer preventive effect of RES. We conducted a clinical study to determine the effect of pharmacological doses of RES on drug and carcinogen metabolizing enzymes.

Methods: Forty-two healthy volunteers underwent baseline assessment of Phase I and Phase II enzymes. A cocktail of cytochrome P450 (CYP) metabolic probe drugs, including caffeine, dextromethorphan, losartan, and buspirone, were administered to assess the activity of CYP1A2, 2D6, 2C9, and 3A4, respectively. Blood and urine samples were collected for 8 hours after probe drug administration to determine parent probe drug and metabolite concentrations for measurements of CYP enzyme activities. Blood lymphocyte glutathione S-transferase (GST) activity and GST-π level, and serum total and direct bilirubin, a surrogate for UDP-glucuronosyl transferase (UGT) 1A1 activity, were measured to assess Phase II enzymes. After the baseline evaluation, study participants took 1 gm of RES once daily for 4 wks. Enzyme assessment was repeated upon intervention completion.

Results: RES intervention was found to suppress the activity of CYP3A4, 2D6, and 2C9. The geometric mean change of the activity index of CPY3A4, 2D6, and 2C9 was 33% (p = 0.01), 70% (p = 0.01), and 171% (p &lt; 0.0001), respectively. CYP1A2 activity was induced; the geometric mean change of the activity index was 16% (p = 0.005). The overall GST and UGT1A1 activity index were minimally affected by the intervention while an induction of GST-π level (84%, p = 0.002) and UGT1A1 activity index (20%, p = 0.0089) was observed in individuals with baseline enzyme level/activity in the lowest tertile.

Conclusion: We conclude that high doses of RES administration may modulate enzyme systems involved in carcinogen activation and detoxification, which may be one mechanism by which RES inhibits carcinogenesis. However, high doses of RES administration may lead to clinically relevant metabolic drug interactions. Further clinical studies are needed to determine whether lower doses of RES could be used to achieve cancer preventive activities. (Supported by N01CN35158 from the National Cancer Institute, Division of Cancer Prevention)

Citation Information: Cancer Prev Res 2010;3(1 Suppl):A57.

Abstract A79: Human breast tissue bioavailability of topically applied limonene

Purpose: Limonene is a monocyclic monoterpene found at high concentration in citrus peel oil and has demonstrated anti-cancer effects in preclinical studies of mammary carcinogenesis. However, the effective oral dose determined in rodents extrapolates to a human dose that may not be feasible for long-term consumption. Limonene is highly lipophilic and has been long explored as an enhancer for percutaneous absorption of pharmaceutical drugs, including tamoxifen. Preliminary work from our group demonstrated that topically applied limonene is absorbed through the mouse skin and accumulates in the mammary glands.

Methods: We conducted a pilot clinical study to determine whether limonene would be bioavailable in the breast following topical application. In the first study phase, we recruited 19 healthy women to apply limonene containing massage oil to the breast daily or 3x/wk. Nipple aspirate fluid (NAF) and plasma samples were collected before and after 4 weeks of limonene massage application. Sample limonene concentrations were determined using gas chromatography-mass spectrometry. In the second study phase, we recruited 25 healthy women to undergo 4 weeks of daily limonene massage oil application to the breast. Potential agent effect biomarkers were determined in NAF and plasma collected before and after the limonene massage application.

Results: In samples collected from the first study phase, no significant increase in NAF and plasma limonene levels was observed following the limonene massage application, possibly because limonene deposits in the fatty breast tissue with minimal secretion to NAF or systemic circulation. Changes in agent effect biomarkers in NAF, including TGF-beta, EGF, and adiponectin, were evaluated in the second study phase for determination of the breast tissue limonene bioavailability. There were no consistent changes in the agent effect biomarkers overall or in pre-menopausal women following the limonene massage application. However, among the post-menopausal women (n =8), there were significant increases in NAF levels of TGF-beta (p = 0.005) and EGF (p = 0.032), and there was an increasing trend in adiponectin (p = 0.164, n=5 due to limited NAF volume).

Conclusions: We conclude that breast massage application of limonene containing massage oil did not result in consistent changes in limonene secretion to the NAF and the potential drug effect biomarkers in NAF. However, limonene massage application increased the NAF expression of TGF-beta and EGF in post-menopausal women, indicative of the intervention effects in the breast tissue. Further studies are needed to explore the potential effects of topical limonene massage intervention on carcinogenesis biomarkers in a larger cohort of post-menopausal women. Supported by Department of Defense, BCRP Idea Award, BC061529

Citation Information: Cancer Prev Res 2010;3(1 Suppl):A79.

The effects of temperature and water concentration on the otolith incorporation of barium and manganese in black rockfish Sebastes melanops

Observations of multiple years of geographic variation in [Ba:Ca](otolith) and [Mn:Ca](otolith) in black rockfish Sebastes melanops prompted this study to examine the effects of temperature and water concentration on the otolith incorporation of Ba and Mn in this wholly marine species. The replicated experiment design consisted of two water temperatures (7.4 and 13.0 degrees C) and four water concentrations of Ba:Ca and Mn:Ca. A positive, linear relationship between [Ba:Ca](water) and [Ba:Ca](otolith) was observed at both temperatures. A positive temperature effect was also observed with mean partition coefficients for Ba (D(Ba)) greater in the 13 degrees C than in the 7.4 degrees C treatments (mean = 0.061 and 0.048, respectively). There was no relationship between [Mn:Ca](water) and [Mn:Ca](otolith) although a negative temperature effect was observed. Mean partition coefficients for Mn (D(Mn)) were lower in the 13 degrees C than in the 7.4 degrees C treatments (mean = 0.027 and 0.036, respectively). The data presented support the assumption of a positive, linear relationship between water and otolith Metal:Ca concentrations for Ba:Ca but not for Mn:Ca. Thus, although indicative of residence in distinct water masses, observed variation in [Metal:Ca](otolith) may not reflect variation in water concentration and can be affected by temperature. Caution should be applied in the interpretation of geographic variation of [Mn:Ca](otolith) until the mechanisms regulating its incorporation are more fully understood.

Efficacy of eprinomectin and doramectin against Amblyomma americanum (Acari: Ixodidae) on cattle

Steers were treated with doramectin or eprinomectin by daily oral capsule for 28 consecutive days. The level of doramectin in the serum of steers treated at 200 microg/kg/d reached a maximum of 104.0 +/- 22.1 ppb at day 21 and declined from 93.3 +/- 20.5 ppb on the final day of treatment to below detectable by day 56. Steers treated at 50 microg/kg/d reached a maximum level of doramectin in the serum of 24.7 +/- 1.2 ppb on day 21 and declined from 24.7 +/- 0.6 ppb on the final day of treatment to less than detectable on day 42. Both doramectin dosages provided 100% control of estimated larvae (EL) of Amblyomma americanum (L.) (Acari: Ixodidae) throughout the 28-d treatment period. Daily oral treatment with eprinomectin at a dosage of 200 microg/kg for 28 consecutive days produced a maximum concentration in the serum of 41.6 +/- 11.0 ppb at day 14. On the final day of eprinomectin treatment, the serum concentration was 38.3 +/- 5.9 ppb. Seven days later at day 35, eprinomectin was not detectable in the serum. For steers treated at 50 microg/kg/d for 28 consecutive days, the serum level of eprinomectin reached a maximum of 10.0 +/- 3.0 ppb on day 28 and was undetectable on day 35. Both eprinomectin dosages provided complete control of EL of A. americanum during the 28-d treatment period. Because eprinomectin is efficacious against A. americanum at lower serum levels in cattle and is eliminated from the serum at a more rapid rate than either doramectin or ivermectin, it provides advantages for use in applications such as the medicated bait for control of ticks on white-tailed deer and could have potential for use in the Cattle Fever Tick Eradication Program.

A sustained release gel formulation of doramectin for control of lone star ticks (Acari: Ixodidae) and horn flies (Diptera: Muscidae) on cattle

A gel formulation formed by incorporating technical doramectin into a 10% hydroxypropyl methylcellulose aqueous solution was used to subcutaneously inject steers at varying dosages. Doramectin serum concentration of steers receiving 600 microg (AI)/kg body weight declined from 21.9 ppb at 0.5 wk to below detectable at 8 wk postinjection. The 1,200 microg (AI)/kg injection resulted in serum concentrations of 29.1 ppb at 0.5 wk and declined to 0.5 ppb at 8 wk postinjection. Both the 600 and 1,200 microg (AI)/kg injections provided 100% inhibition of index of fecundity (IF) in adult lone star ticks, Amblyomma americanum L. (Acari: Ixodidae) through week 8, after which inhibition declined to 79.4 and 45.3%, respectively, during the 12th week posttreatment. For steers treated at 600 microg (AI)/kg, mortality of adult horn flies, Hematobia irritans L. (Diptera: Muscidae), declined from 16.9% during week 2 to 3.1% during week 7 postinjection. The blood from steers treated at 1,200 microg (AI)/kg resulted in a similar decline in mortality of blood fed adult horn flies from 29.4% during week 1 to 4.0% during week 7. The 600 microg (AI)/kg treatment provided complete control of larval horn flies in the manure for 9 wk, whereas the 1,200 microg (AI)/kg injection gave complete control for 14 wk posttreatment. The doramectin gel formulation provided long-lasting delivery of doramectin to cattle and extended control of lone star ticks and larval horn flies. Such a simple and inexpensive formulation could be useful in tick eradication programs by reducing the frequency of gathering cattle.

Reduced interference by gray squirrels with 4-poster deer treatment bait stations by using timed-release bait

When white-tailed deer, Odocoileus virginianus, feed on corn bait dispensed by 4-poster tick control devices, they rub against paint rollers impregnated with acaricide. Gray squirrels, Sciurus carolinensis, also feed on the corn bait in the feeding troughs of 4-posters, but in doing so, leave abundant corn fragments and meal that impede the flow of uneaten corn into the troughs. Large accumulations of fragments and meal adversely affect the operation of 4-posters and their use by deer. A battery-operated closure mechanism controlled by a photo sensor was developed to block the flow of corn into the troughs during the day when squirrels are active and deer infrequently visit 4-posters. The effectiveness of the diurnal corn restriction (DCR) concept and restriction mechanism was tested in a field trial at a tick-infested site in Maryland. DCR effectively eliminated accumulation of whole corn, partially eaten corn and corn meal in corn troughs associated with squirrel feeding. At the same time, deer usage of 4-posters was not diminished.

Determination of d-limonene in adipose tissue by gas chromatography-mass spectrometry

We developed a novel method for analyzing d-limonene levels in adipose tissue. Fat samples were subjected to saponification followed by solvent extraction. d-Limonene in the sample extract was analyzed using gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring. Linear calibration curves were established over the mass range of 79.0-2529 ng d-limonene per 0.1g of adipose tissue. Satisfactory within-day precision (R.S.D. 6.7-9.6%) and accuracy (%difference of -2.7 to 3.8%) and between-day precision (R.S.D. 6.0-10.7%) and accuracy (%difference of 1.8-2.6%) were achieved. The assay was successfully applied to human fat biopsy samples from a d-limonene feeding trial.

The effect of oral contraceptives on the nitric oxide system and renal function

We have demonstrated that oral contraceptive (OC) users exhibit elevated angiotensin II levels and angiotensin II type 1 receptor expression, indicative of renin-angiotensin system (RAS) activation, yet the renal and systemic consequences are minimal, suggesting that there is increased vasodilatory activity, counteracting the effect of RAS activation. We hypothesized that the nitric oxide (NO) system would be upregulated in OC users and that this would be reflected by a blunted hemodynamic response to l-arginine infusion. All subjects were studied after a 7-day controlled sodium and protein diet. Inulin and para-aminohippurate clearance techniques were used to assess renal function. l-Arginine was infused at 100, 250, and 500 mg/kg, each over 30 min. Skin endothelial NO synthase mRNA expression was assessed by real-time PCR. While OC nonusers exhibited significant increases in effective renal plasma flow (670.8 +/- 35.6 to 816.2 +/- 59.7 ml.min(-1).1.73 m(-2)) and glomerular filtration rate (133.4 +/- 4.3 to 151.0 +/- 5.7 ml.min(-1).1.73 m(-2), P = 0.04) and declines in renal vascular resistance (81.1 +/- 6.1 to 63.5 +/- 6.2 mmHg.ml(-1).min, P = 0.001) at the lower l-arginine infusion rates, the responses in OC users were blunted. While l-arginine reduced mean arterial pressure at the 250 and 500 mg/kg doses in OC nonusers, OC users only exhibited a decrease in mean arterial pressure at the highest infusion rate. In contrast, tissue endothelial NO synthase mRNA levels were higher in the OC users (P = 0.04). In summary, these findings suggest that the NO system is upregulated by OC use in young, healthy women. Increased activity of the NO pathway may modulate the hemodynamic effects of RAS activation in OC users.