Early-onset prescription drug misuse in Indiana youth.

BACKGROUND: Based on 2018 national estimates, approximately 5-10% of youth between the ages of 12-17 report past year prescription drug misuse (PDM) in the United States. PDM among adolescents is associated with negative health outcomes and risk behaviors. The current study examined both the prevalence of PDM among diverse groups of adolescents and the association of alcohol and cigarette use with early PDM. METHODS: Data came from the cross-sectional state-based 2018 Indiana Youth Survey of students from grades 6-12, ranging in age from 10 to 17 years (n = 80,926). Lifetime PDM, alcohol, and cigarettes were assessed by self-report, including ages at first use. A series of analyses were conducted separately for non-Hispanic Black, non-Hispanic White, and Hispanic students. We estimated the prevalence of PDM. Likelihood of PDM was estimated using the Kaplan-Meier survivor function. Cox proportional hazards regression models estimated age at first PDM from ages at first use of alcohol and cigarettes. RESULTS: Three percent of non-Hispanic Black, 4% of non-Hispanic White, and 5% of Hispanic students reported PDM. Onset of smoking was associated with first PDM across adolescence for all groups. Onset of drinking was associated with first PDM among Hispanic students across adolescence. For Non-Hispanic Black and Non-Hispanic White students, likelihood of PDM was most pronounced during very early adolescence. CONCLUSIONS: Onset of alcohol and cigarette use were associated with of PDM among Indiana youth, suggesting that interventions aimed at preventing early smoking and drinking may also reduce PDM among youth.

Staging and operability of primary lung cancer in Western Cape Province, South Africa.

Background: Lung cancer is the leading cause of cancer-related death globally and in South Africa. Historically, the majority of patients diagnosed with lung cancer are incurable at presentation. Objectives: To assess the tumour, nodes, metastasis (TNM) staging of lung cancer in a centre with access to both positron emission tomography-computed tomography (PET-CT) and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) using a structured diagnostic approach and to compare results with a historical cohort from 2009 from the same hospital. Methods: A retrospective descriptive observational study was performed using the registry of a high-volume tertiary hospital's weekly multidisciplinary thoracic oncology meeting (MDT). A structured diagnostic approach was used for staging purposes. All patients with a tissue diagnosis of primary lung cancer and adequate imaging (chest CT and/or PET-CT) who presented at the MDT during the period from 1 January - 31 December 2019 were included. Final staging and tissue diagnoses were documented and compared with a historical cohort from 2009 from the same institution. Results: Adenocarcinoma was the most common subtype (38.8%; n=116). Less than a tenth of patients (6.3%; n=16/254) with non-small cell lung cancer had potentially curable lung cancer (stage IA to IIIA) at presentation, significantly less than the 2009 cohort (14.5%; n=25/173; p=0.007). The most common procedure administered on patients was transthoracic needle aspiration (37.54%; n=112), followed by conventional bronchoscopic needle aspiration or biopsy (20.4%; n=61), and EBUS-TBNA (17.1%; n=51/299). After PET-CT, 19/30 cases were upstaged including 9/18 from potentially resectable to unresectable. Two of these cases were down-staged to potentially resectable following EBUS-TBNA. Conclusion: There was a significant decline in resectable and potentially curable lung cancer at presentation over a 10-year period. PET-CT and EBUS-TBNA improved the accuracy of non-small cell lung cancer staging among patients with resectable and potentially curable lung cancer but have exposed a higher stage profile.

The Menstrual Disorder of Teenagers (MDOT) Study No. 2: Period ImPact and Pain Assessment (PIPPA) Tool Validation in a Large Population-Based Cross-Sectional Study of Australian Teenagers.

STUDY OBJECTIVE: To validate the Period ImPact and Pain Assessment (PIPPA) self-screening tool for menstrual disturbance in teenagers. DESIGN: Cross-sectional study. SETTING: Three senior high schools in the Australian Capital Territory (ACT), Australia. PARTICIPANTS: A total of 1066 girls between 15 and 19 years of age. INTERVENTIONS AND MAIN OUTCOME MEASURES: A quantitative paper survey collected self-reports of menstrual bleeding patterns, typical and atypical symptoms, morbidities, and interference with daily activities. Multiple correspondence analysis was used to examine associations between PIPPA questions. Generalized linear models compared total score and subscores by validation criteria: pain, school absence, and body mass index (BMI). Receiver operating characteristic curves were used to evaluate the predictiveness of menstrual disturbance indicators by total PIPPA score. RESULTS: Reports of pain, interference, and concern within the PIPPA items and between both the MDOT and PIPPA questionnaires were significantly correlated (P < .0001). The indicator "missing school" was highly associated (P < .0001) with pain and interference. Obesity (BMI ≥30) was associated with higher PIPPA scores, as was underweight (BMI≤18.4). Where 0 = no disturbance, 5 = high disturbance, aggregated PIPPA scores found 75% scoring 0-2 (out of 5) and 25% scoring 3-5 (257/1037). High scores of 4 or 5 (out of 5) were 7% (72/1037) and 3.7% (38/1037), respectively. CONCLUSION: PIPPA is a valid screening tool for pain-related menstrual disturbance that affects functioning in young women. PIPPA subdomains of pain/interference have good validity relative to indicators of pain and interference and are responsive to age, BMI, and school absence differences.

Bacterial infection, antibiotic use and COVID-19: Lessons from the intensive care unit.

BACKGROUND: Empirical broad-spectrum antibiotics are frequently prescribed to patients with severe COVID-19, motivated by concern about bacterial coinfection. There is no evidence of benefit from such a strategy, while the dangers of inappropriate antibiotics are well described. OBJECTIVES: To investigate the frequency, profile and related outcomes of infections by bacterial pathogens in patients admitted to an intensive care unit (ICU) with severe COVID-19 pneumonia. METHODS: This was a prospective, descriptive study in a dedicated COVID-19 ICU in Cape Town, South Africa, involving all adult patients admitted to the ICU with confirmed COVID-19 pneumonia between 26 March and 31 August 2020. We collected data on patient comorbidities, laboratory results, antibiotic treatment, duration of admission and in-hospital outcome. RESULTS: We included 363 patients, who collectively had 1 199 blood cultures, 308 tracheal aspirates and 317 urine cultures performed. We found positive cultures for pathogens in 20 patients (5.5%) within the first 48 hours of ICU admission, while 73 additional patients (20.1%) had positive cultures later during their stay. The most frequently isolated pathogens at all sites were Acinetobacter baumannii (n=54), Klebsiella species (n=13) and coagulase-negative staphylococci (n=9). Length of ICU stay (p<0.001) and intubation (p<0.001) were associated with positive cultures on multivariate analysis. Disease severity (p=0.5), early antibiotic use (p=0.5), diabetes mellitus (p=0.1) and HIV (p=0.9) were not associated with positive cultures. Positive cultures, particularly for tracheal aspirates (p<0.05), were associated with longer ICU length of stay and mortality. Early empirical antibiotic use was not associated with mortality (odds ratio 2.5; 95% confidence interval 0.95 - 6.81). CONCLUSIONS: Bacterial coinfection was uncommon in patients at the time of admission to the ICU with severe COVID-19. Avoiding early empirical antibiotic therapy is therefore reasonable. Strategies to avoid coinfection and outbreaks in hospital, such as infection prevention and control, as well as the strict use of personal protective equipment, are important to improve outcomes.

Autosegmentation of the rectum on megavoltage image guidance scans.

Autosegmentation of image guidance (IG) scans is crucial for streamlining and optimising delivered dose calculation in radiotherapy. By accounting for interfraction motion, daily delivered dose can be accumulated and incorporated into automated systems for adaptive radiotherapy. Autosegmentation of IG scans is challenging due to poorer image quality than typical planning kilovoltage computed tomography (kVCT) systems, and the resulting reduction of soft tissue contrast in regions such as the pelvis makes organ boundaries less distinguishable. Current autosegmentation solutions generally involve propagation of planning contours to the IG scan by deformable image registration (DIR). Here, we present a novel approach for primary autosegmentation of the rectum on megavoltage IG scans acquired during prostate radiotherapy, based on the Chan-Vese algorithm. Pre-processing steps such as Hounsfield unit/intensity scaling, identifying search regions, dealing with air, and handling the prostate, are detailed. Post-processing features include identification of implausible contours (nominally those affected by muscle or air), 3D self-checking, smoothing, and interpolation. In cases where the algorithm struggles, the best estimate on a given slice may revert to the propagated kVCT rectal contour. Algorithm parameters were optimised systematically for a training cohort of 26 scans, and tested on a validation cohort of 30 scans, from 10 patients. Manual intervention was not required. Comparing Chan-Vese autocontours with contours manually segmented by an experienced clinical oncologist achieved a mean Dice Similarity Coefficient of 0.78 (SE < 0.011). This was comparable with DIR methods for kVCT and CBCT published in the literature. The autosegmentation system was developed within the VoxTox Research Programme for accumulation of delivered dose to the rectum in prostate radiotherapy, but may have applicability to further anatomical sites and imaging modalities.

Trend differences in men and women in rural and urban U.S. settings.

BACKGROUND: Smoking prevalence is declining at a slower rate in rural than urban settings in the United States (U.S.), and known predictors of smoking do not readily account for this trend difference. Given that socioeconomic and psychosocial determinants of health disparities accumulate in rural settings and that life-course disadvantages are often greater in women than men, we examined whether smoking trends are different for rural and urban men and women. METHOD: We used yearly cross-sectional data (n = 303,311) from the U.S. National Survey on Drug Use and Health (NSDUH) from 2007 through 2014 to compare cigarette smoking trends in men and women across rural and urban areas. Current smoking status was modelled using logistic regression controlling for confounding risk factors. RESULTS: Regression derived graphs predicting unadjusted prevalence estimates and 95% confidence bands revealed that whereas the smoking trends of rural men, urban men, and urban women significantly declined from 2007 to 2014, the trend for rural women was flat. Controlling for demographic, socioeconomic and psychosocial predictors of smoking did not explain rural women's significantly different trend from those of the other three groups. CONCLUSION: Rural women lag behind rural men, urban men and urban women in decreasing smoking, a health disparity finding that supports the need for tobacco control and regulatory policies and interventions that are more effective in reducing smoking among rural women.

Automatic contour propagation using deformable image registration to determine delivered dose to spinal cord in head-and-neck cancer radiotherapy.

To determine delivered dose to the spinal cord, a technique has been developed to propagate manual contours from kilovoltage computed-tomography (kVCT) scans for treatment planning to megavoltage computed-tomography (MVCT) guidance scans. The technique uses the Elastix software to perform intensity-based deformable image registration of each kVCT scan to the associated MVCT scans. The registration transform is then applied to contours of the spinal cord drawn manually on the kVCT scan, to obtain contour positions on the MVCT scans. Different registration strategies have been investigated, with performance evaluated by comparing the resulting auto-contours with manual contours, drawn by oncologists. The comparison metrics include the conformity index (CI), and the distance between centres (DBC). With optimised registration, auto-contours generally agree well with manual contours. Considering all 30 MVCT scans for each of three patients, the median CI is [Formula: see text], and the median DBC is ([Formula: see text]) mm. An intra-observer comparison for the same scans gives a median CI of [Formula: see text] and a DBC of ([Formula: see text]) mm. Good levels of conformity are also obtained when auto-contours are compared with manual contours from one observer for a single MVCT scan for each of 30 patients, and when they are compared with manual contours from six observers for two MVCT scans for each of three patients. Using the auto-contours to estimate organ position at treatment time, a preliminary study of 33 patients who underwent radiotherapy for head-and-neck cancers indicates good agreement between planned and delivered dose to the spinal cord.

Delivered dose can be a better predictor of rectal toxicity than planned dose in prostate radiotherapy.

BACKGROUND AND PURPOSE: For the first time, delivered dose to the rectum has been calculated and accumulated throughout the course of prostate radiotherapy using megavoltage computed tomography (MVCT) image guidance scans. Dosimetric parameters were linked with toxicity to test the hypothesis that delivered dose is a stronger predictor of toxicity than planned dose. MATERIAL AND METHODS: Dose-surface maps (DSMs) of the rectal wall were automatically generated from daily MVCT scans for 109 patients within the VoxTox research programme. Accumulated-DSMs, representing total delivered dose, and planned-DSMs, from planning CT data, were parametrised using Equivalent Uniform Dose (EUD) and 'DSM dose-width', the lateral dimension of an ellipse fitted to a discrete isodose cluster. Associations with 6 toxicity endpoints were assessed using receiver operator characteristic curve analysis. RESULTS: For rectal bleeding, the area under the curve (AUC) was greater for accumulated dose than planned dose for DSM dose-widths up to 70Gy. Accumulated 65Gy DSM dose-width produced the strongest spatial correlation (AUC 0.664), while accumulated EUD generated the largest AUC overall (0.682). For proctitis, accumulated EUD was the only reportable predictor (AUC 0.673). Accumulated EUD was systematically lower than planned EUD. CONCLUSIONS: Dosimetric parameters extracted from accumulated DSMs have demonstrated stronger correlations with rectal bleeding and proctitis, than planned DSMs.

Geant4 simulation of the Elekta XVI kV CBCT unit for accurate description of potential late toxicity effects of image-guided radiotherapy.

This paper describes the modelisation of the Elekta XVI Cone Beam Computed Tomography (CBCT) machine components with Geant4 and its validation against calibration data taken for two commonly used machine setups. Preliminary dose maps of simulated CBCTs coming from this modelisation work are presented. This study is the first step of a research project, GHOST, aiming to improve the understanding of late toxicity risk in external beam radiotherapy patients by simulating dose depositions integrated from different sources (imaging, treatment beam) over the entire treatment plan. The second cancer risk will then be derived from different models relating irradiation dose and second cancer risk.

Efficient biologically inspired photocell enhanced by delocalized quantum states.

Artificially implementing the biological light reactions responsible for the remarkably efficient photon-to-charge conversion in photosynthetic complexes represents a new direction for the future development of photovoltaic devices. Here, we develop such a paradigm and present a model photocell based on the nanoscale architecture and molecular elements of photosynthetic reaction centers. Quantum interference of photon absorption and emission induced by the dipole-dipole interaction between molecular excited states guarantees an enhanced light-to-current conversion and power generation for a wide range of electronic, thermal, and optical parameters for optimized dipolar geometries. This result opens a promising new route for designing artificial light-harvesting devices inspired by biological photosynthesis and quantum technologies.

The menstrual disorder of teenagers (MDOT) study: determining typical menstrual patterns and menstrual disturbance in a large population-based study of Australian teenagers.

OBJECTIVE: The aim of this study was to: (1) establish the typical experience of menstruation for senior high school girls and (2) determine how many experience considerable menstrual disturbance that could require further investigation and management of underlying pathology. DESIGN: Cross-sectional study. SETTING: Senior High Schools in the Australian Capital Territory (ACT), Australia. POPULATION: A total of 1051 girls aged between 15 and 19 years. METHODS: Data based on a quantitative survey. MAIN OUTCOME MEASURES: Self-reports of menstrual bleeding patterns, typical and atypical symptoms and morbidities. RESULTS: Typical menstruation in adolescence includes pain (93%), cramping (71%), premenstrual symptoms (96%) and mood disturbance (73%). Highly significant associations were found between increasing severity of menstrual pain, number of menstrual-related symptoms, interference with life activities and school absence. These associations indicate that approximately 25% of the sample had marked menstrual disturbance: 21% experienced severe pain; 26% school absence; 26% suffering five or more symptoms; > or =24% reporting moderate to high interference with four out of nine life activities. Approximately 10% reported atypical symptoms associated with menstruation. Diagnosis of menstrual pathology in the sample was low, even though 33% had seen a GP and 9% had been referred to a specialist. CONCLUSIONS: Menstrual pain and symptoms are common in teenagers. Girls indicating moderate to severe pain in association with a high number of menstrual symptoms, school absence and interference with life activities should be effectively managed to minimise menstrual morbidity. Those girls who do not respond to medical management should be considered for further investigation for possible underlying pathology, such as endometriosis.

Alemtuzumab induction and prednisone-free maintenance immunotherapy in simultaneous pancreas-kidney transplantation comparison with rabbit antithymocyte globulin induction - long-term results.

This study compared the effects of using two T-cell depleting antibodies, alemtuzumab (anti-CD 52, Campath-1H) and rabbit antithymocyte globulin (Thymoglobulin), as induction immunosuppression for recipients of simultaneous pancreas-kidney transplantation given a prednisone-free maintenance regimen. We used a single-center, nonrandomised, retrospective, sequential study design to evaluate the efficacy and safety of alemtuzumab (n = 50) or antithymocyte globulin (n = 38) induction in combination with a prednisone-free, tacrolimus/sirolimus-based immunosuppression protocol. Kaplan-Meier analyses of long-term patient and graft survivals and rejection rates were determined according to induction agent. Secondary endpoints included the quality of renal allograft function, incidence of infectious and malignant complications, and cost considerations. Overall long-term patient and graft survival rates did not significantly differ between patients treated with alemtuzumab and antithymocyte globulin. Rejection rates were also nearly equivalent at 1 and 2 years. Viral infectious complications were statistically significantly lower in the alemtuzumab group. The cost of alemtuzumab induction was lower than antithymocyte globulin. Alemtuzumab induction followed by steroid-free maintenance therapy with a tacrolimus/sirolimus-based immunosuppression regimen provided an effective, safe and cost-conscious approach to SPK transplantation.

Genetic markers for analysing symbiotic relationships and lateral gene transfer in Neotropical bradyrhizobia.

Assays with seven sets of lineage-specific polymerase chain reaction (PCR) primers in the ribosomal RNA region were performed on 96 isolates of the Bradyrhizobium sp. nodule bacteria from Barro Colorado Island, Panama. The isolates were derived from 10 legume host species in six genera (Centrosema, Desmodium, Dioclea, Inga, Machaerium and Vigna). The PCR assays differentiated 13 composite genotypes, and sequencing of a 5' 23S rRNA region indicated that all but one had a unique sequence. The most common genotype (seen in 44% of the isolates) was associated with all six legume host genera, and had a marker profile and 5' 23S rRNA sequence identical to a Bradyrhizobium lineage associated with several other legume genera in Panama and Costa Rica. Another 46% of the isolates had genotypes found to be associated with two to three legume genera. Bradyrhizobium strains with low host specificity thus appear to be prevalent in this tropical forest. Based on 16S rRNA and 5' 23S rRNA markers, most of the isolates had clear affinities to either B. japonicum or B. elkanii. However, one strain (Cp5-3) with a B. elkanii-type 16S rRNA marker had a 5' 23S rRNA region resembling B. japonicum. A partition homogeneity test indicated that relationships of strain Cp5-3 were significantly discordant for 16S rRNA vs. 23S rRNA sequences, and a runs test detected significant mosaic structure across the rRNA region. Lateral gene transfer events have therefore played a role in the evolution of symbiotic bacteria in this environment.

Over-expression of cyclin D1 regulates Cdk4 protein synthesis.

Increased Cdk4 expression occurs coincident with over-expression of cyclin D1 in many human tumours and tumourigenic mouse models. Here, we investigate both in vivo and in vitro the mechanism by which Cdk4 expression is regulated in the context of cyclin D1 over-expression. Cdk4 mRNA levels in cyclin D1-over-expressing tissue and cultured cells were unchanged compared with controls. In contrast, Cdk4 protein levels were increased in cyclin D1-over-expressing tissue and cells versus their respective controls. This increase was not due to altered protein stability, but appeared to be due to an increase in Cdk4 protein synthesis. We also performed immunoprecipitation and in vitro kinase assays to demonstrate an increase in cyclin D1-Cdk4 complex formation and associated kinase activity. Blocking cyclin D1 expression resulted in diminished Cdk4 protein but not mRNA levels. These findings suggest a mechanism by which Cdk4 expression is increased in the context of cyclin D1 over-expression during tumourigenesis.

Psychiatric morbidity and screening for colorectal cancer.

BACKGROUND: Several studies have shown that faecal occult blood (FOB) screening reduces mortality from colorectal cancer. However, concern has been expressed that health screening may have adverse psychological effects, particularly for the group returning false positive tests. OBJECTIVES: To evaluate any adverse psychological effects associated with faecal occult blood screening. SETTING: Randomised controlled trial of faecal occult blood screening for colorectal cancer. METHODS: Psychiatric morbidity was measured, using the general health questionnaire (GHQ) before and 3 months after the offer of screening for colorectal cancer with FOB testing. Scores were related to acceptance of the screening test. A smaller cohort, who had returned positive FOB tests, had anxiety levels measured, using the Spielberger anxiety inventory (SAI), at different times during screening, investigation, and follow up. RESULTS: A GHQ was sent to 2184 subjects before the offer of screening, and 1541 (70.6%) were returned. Of the 1693 subjects offered the GHQ 3 months after the offer of screening, 1303 (77%) returned it. A GHQ score of 5 or more, indicating possible psychiatric morbidity, was present in 454 subjects (29.5%) before screening and in 386 (29.6%) subjects 3 months after screening (NS). Of the 454 subjects who scored 5 or more, 241 (53.1%) accepted screening and 213 (46.9%) refused. A total of 1081 subjects scored less than 5, and of these 521 (48.2%) accepted screening and 560 (51.8%) refused (NS). Anxiety scores were measured in 100 test positive patients and were highest after notification of a positive test and before investigation by colonoscopy. In patients with false positive results, scores fell the day after colonoscopy and remained low 1 month later. CONCLUSIONS: The receipt of a screening test does not cause sustained anxiety and the existence of psychiatric morbidity is not a factor affecting a person's decision to accept or refuse a screening test for colorectal cancer.

Limits of detection of regional differences in vasodilated flow in viable myocardium by first-pass magnetic resonance perfusion imaging.

BACKGROUND: Perfusion imaging techniques intended to identify regional limitations in coronary flow reserve in viable myocardium need to identify 2-fold differences in regional flow during coronary vasodilation consistently. This study evaluated the suitability of current first-pass magnetic resonance approaches for evaluating such differences, which are 1 to 2 orders of magnitude less than in myocardial infarction. METHODS AND RESULTS: Graded regional differences in vasodilated flow were produced in chronically instrumented dogs with either left circumflex (LCx) infusion of adenosine or partial LCx occlusion during global coronary vasodilation. First-pass myocardial signal intensity-time curves were obtained after right atrial injection of gadoteridol (0.025 mmol/kg) with an MRI inversion recovery true-FISP sequence. The area under the initial portion of the LCx curve was compared with that of a curve from a remote area of the ventricle. Relative LCx and remote flows were assessed simultaneously with microspheres. The ratio of LCx and remote MRI curve areas and the ratio of LCx and remote microsphere concentrations were highly correlated and linearly related over a 5-fold range of flow differences (y=0.96 x+/-0.07, P<0.0001, r(2)=0.87). The 95% confidence limits for individual MRI measurements were +/-35%. Regional differences of >/=2-fold were consistently apparent in unprocessed MR images. CONCLUSIONS: Clinically relevant regional reductions in vasodilated flow in viable myocardium can be detected with 95% confidence over the range of 1 to 5 times resting flow. This suggests that MRI can identify and quantify limitations in perfusion reserve that are expected to be produced by stenoses of >/=70%.

Rhizobitoxine production and symbiotic compatibility of Bradyrhizobium from Asian and North American lineages of amphicarpaea.

Reciprocal inoculations with Bradyrhizobium sp. isolates from the North American legume Amphicarpaea bracteata (L.) Fern. (Phaseoleae-Glycininae) and from a Japanese population of its close relative Amphicarpaea edgeworthii (Benth.) var. japonica were performed to analyze relative symbiotic compatibility. Amphicarpaea edgeworthii plants formed few or no nodules with any North American bradyrhizobial strains isolated from A. bracteata, but all A. bracteata lineages formed effective nitrogen-fixing nodules with Japanese Bradyrhizobium isolates from A. edgeworthii. However, one group of A. bracteata plants (lineage Ia) when inoculated with Japanese bradyrhizobia developed a striking leaf chlorosis similar to that known to be caused by rhizobitoxine. The beta-cystathionase inhibition assay demonstrated that significant amounts of rhizobitoxine were present in nodules formed by these Japanese bradyrhizobia. No North American bradyrhizobial isolate from A. bracteata induced chlorosis on any plants, and the beta-cystathionase assay failed to detect rhizobitoxine in nodules formed by these isolates. The role of rhizobitoxine in A. edgeworthii nodulation development was tested by inoculating plants with a Bradyrhizobium elkanii rhizobitoxine-producing strain, USDA 61, and two mutant derivatives, RX17E and RX18E, which are unable to synthesize rhizobitoxine. Amphicarpaea edgeworthii inoculated with wild-type USDA 61 developed >150 nodules per plant, while plants inoculated with RX17E and RX18E developed fewer than 10 nodules per plant. Thus, efficient nodule development in A. edgeworthii appears to be highly dependent on rhizobitoxine production by Bradyrhizobium strains.

Nuclear magnetic resonance study of doxorubicin binding to cardiolipin containing magnetically oriented phospholipid bilayers.

Doxorubicin (DOX) is a potent anthracycline cancer drug whose interaction with anionic membrane phospholipids, such as cardiolipin (CL), is thought to contribute to its cytotoxicity as well as induce cardiotoxic side effects. We have studied the interaction of DOX with a CL containing model membrane system using high resolution, oriented sample (31)P and (2)H NMR. The model membrane system is composed of a bilayer forming phospholipid and a detergent that breaks the extended bilayers into disc-shaped micelles (bicelles) that can orient in a magnetic field. The effects of DOX on the phospholipid bilayer were monitored using samples containing dimyristoylphosphatidylcholine (DMPC), selectively deuterated in either headgroup or acyl chain positions, and measuring the changes in (2)H quadrupolar splittings as DOX was added. Changes in quadrupolar splittings upon DOX addition provide evidence for interaction with both surface and buried sites within the membrane bilayer.