Factors Affecting Prescribing of Type 2 Diabetes Medications in Older Adults within an Integrated Healthcare System

BACKGROUND

Despite type 2 diabetes guidelines recommending against the use of sulfonylureas in older adults and for the use of sodium-glucose cotransporter-2 inhibitors (SGLT2) and glucagon-like peptide-1 agonists (GLP1s) in patients with atherosclerotic cardiovascular disease (ASCVD), chronic kidney disease (CKD), and heart failure (HF), real-world guideline-concordant prescribing remains low. While some factors such as cost have been suggested, an in-depth analysis of the factors associated with guideline-concordant prescribing is warranted.

OBJECTIVE

To quantify the extent of guideline-concordant prescribing in an integrated health care delivery system and examine provider and patient level factors that influence guideline-concordant prescribing.

DESIGN

We performed a cross-sectional study.

PARTICIPANTS

Participants were included if they had a diagnosis of type 2 diabetes, were prescribed a second-line diabetes medication between January 1, 2018 and December 31, 2020 and were at least 65 years old at the time of this second-line prescription.

MAIN MEASURES

Our outcome of interest was guideline-concordant prescribing. The definition of guideline-concordant prescribing was based on American Diabetes Association and American Geriatric Society recommendations as well as expert consensus. Factors affecting guideline concordant prescribing included patient demographics and provider characteristics among others.

KEY RESULTS

We included 1,693 patients of which only 50% were prescribed guideline-concordant medications. In a subgroup of 843 patients with cardiorenal conditions, only 30% of prescriptions were guideline concordant. Prescribing of guideline-concordant prescriptions was more likely among pharmacists than physicians (RR 1.34, 95% CI 1.19-1.51, p<0.001) and in endocrinology practices compared to primary care practices (RR 1.41 95% CI 1.16-1.72, p=0.007). Additionally, guideline concordant prescribing increased over time (42% in 2018 vs 53% in 2019 vs 53% in 2020, p<0.001).

CONCLUSIONS

Guideline-concordant prescribing remains low in older adults, especially among those with cardiorenal conditions. Future studies should examine barriers to prescribing guideline-concordant medications and interventions to improve guideline-concordant prescribing.

Botulinum Toxin A and B Improve Perfusion, Increase Flap Survival, Cause Vasodilation, and Prevent Thrombosis: A Systematic Review and Meta-analysis of Controlled Animal Studies

BACKGROUND

A systematic review and meta-analysis of case-control animal model studies will help clarify the vascular effects of botulinum toxin (BTX).

METHODS

Preferred Reporting Items of Systematic reviews and Meta-Analyses guidelines were used to identify all animal case-control studies published before September 13, 2020, evaluating the vascular effects of BTX. Primary parameters included the following: perfusion, flap survival, arterial and venous dilation, and arterial and venous thrombosis.

RESULTS

Thirty-six studies with 1032 animals met the systematic review inclusion criteria. Twenty-nine studies had quantifiable data for statistical analysis. Statistically significant increases in perfusion with BTX over saline were detected within 1 day and sustained up to 8 weeks. The following represent weighted mean data from the meta-analysis. The administration of BTX has a 26% increase in both random pattern and pedicled flap survival area over controls. Botulinum toxin causes vasodilation. Botulinum toxin increases vessel diameter in arteries by 40% and in veins by 46% compared with saline controls. The administration of BTX reduces thrombosis by 85% in arteries and by 79% in veins compared with saline controls. Vascular effects were consistent across both BTX-A and BTX-B serotypes, multiple animal species, and various doses. No clear relationships between vascular effects and BTX pretreatment time were identified.

CONCLUSIONS

Perivascular BTX administration intraoperatively or as a chemical delay pretreatment several days before surgery in multiple animal species and models shows multiple changes to the vascular system. Extrapolation of lessons learned from this systematic review and meta-analysis of animal models could expand research and clinical use of BTX in human vascular disease and surgery.

Long-term Use of Wearable Health Technology by Chronic Pain Patients

OBJECTIVES

People living with chronic pain may use wearable health technology (WHT) in conjunction with an expert-directed pain management program for up to 1 year. WHT use may be associated with improvements in key patient outcomes.

METHODS

A 12-month study of WHT use among people with chronic pain was conducted, consisting of iPhone and Apple Watch applications to measure movement, sleep, and self-reported pain. Clinical outcomes among 105 patients enrolled in a multidisciplinary pain program that included WHT use were compared with 146 patients in the same program but without WHT, and to 161 patients receiving medical pain management without WHT.

RESULTS

Participants used the WHT on average 143.0 (SD: 117.6) out of 365 days. Mixed-effects models revealed participants who used WHT had decreases in depression scores (-7.83, P <0.01) and prescribed morphine milligram equivalents (-21.55, P =0.04) over 1 year. Control groups also showed decreases in depression scores (-5.08, P =0.01; -5.68, P <0.01) and morphine milligram equivalents (-18.67, P =0.01; -10.99, ns). The estimated slope of change among the WHT was not statistically different than control groups.

DISCUSSION

Patients who used WHT as part of their pain management program demonstrated a willingness to do so for extended periods of time despite living with chronic pain and other comorbidities. Data trends suggest that WHT use may positively impact depression and prescribed medication. Additional research is warranted to investigate the potential of WHT to improve the negative consequences of chronic pain.

Robotic-Arm Assisted Technology's Impact on Knee Arthroplasty and Associated Healthcare Costs

Background: The number of total knee arthroplasties (TKA) carried out globally is expected to substantially rise in the coming decades. Consequently, focus has been increasing on improving surgical techniques and minimizing expenses. Robotic arm-assisted knee arthroplasty has garnered interest to reduce surgical errors and improve precision. Objectives: Our primary aim was to compare the episode-of-care cost up to 90 days for unicompartmental knee arthroplasty (UKA) and TKA performed before and after the introduction of robotic arm-assisted technology. The secondary aim was to compare the volume of UKA vs TKA. Methods: This was a retrospective study design at a single healthcare system. For the cost analysis, we excluded patients with bilateral knee arthroplasty, body mass index >40, postoperative infection, or noninstitutional health plan insurance. Costs were obtained through an integrated billing system and affiliated institutional insurance company. Results: Knee arthroplasty volume increased 28% after the introduction of robotic-assisted technology. The TKA volume increased by 17%, while the UKA volume increased 190%. Post introduction, 97% of UKA cases used robotic arm-assisted technology. The cost analysis included 178 patients (manual UKA, n = 6; robotic UKA, n = 19; manual TKA, n = 58, robotic TKA, n = 85). Robotic arm-assisted TKA and UKA were less costly in terms of patient room and operating room costs but had higher imaging, recovery room, anesthesia, and supply costs. Overall, the perioperative costs were higher for robotic UKA and TKA. Postoperative costs were lower for robotic arm-assisted surgeries, and patients used less home health and home rehabilitation. Discussion: Surgeons performed higher volumes of UKA, and UKA comprised a greater percentage of total surgical volume after the introduction of this technology. The selective cost analysis indicated robotic arm-assisted technology is less expensive in several cost categories but overall more expensive by up to $550 due to higher cost categories including supplies and recovery room. Conclusions: Our findings show a change in surgeons' practice to include increased incidence and volume of UKA procedures and highlights several cost-saving categories through the use of robotic arm-assisted technology. Overall, robotic arm-assisted knee arthroplasty cost more than manual techniques at our institution. This analysis will help optimize costs in the future.

Decline and Pronounced Regional Disparities in Medical Cocaine Usage in the United States

Background: Cocaine is a stimulant and Schedule II drug used as a local anesthetic and vasoconstrictor. Objective: This descriptive study characterized medical cocaine use in the United States. Methods: Retail drug distribution data from 2002 to 2017 were extracted for each state from the Drug Enforcement Administration, which reports on medical, research, and analytical chemistry use. The percentage of buyers (pharmacies, hospitals, and providers) was obtained. Use per state, corrected for population, was determined. Available cross-sectional data on cocaine use as reported by the Medicare and Medicaid programs for 2013-2017 and electronic medical records were examined. Results: Medical cocaine use decreased by -62.5% from 2002 to 2017. Hospitals accounted for 84.9% and practitioners for 9.9% of cocaine distribution in 2017. The number of pharmacies carrying cocaine dropped by -69.4%. The percentages of hospitals, practitioners, and pharmacies that carried cocaine in 2017 were 38.4%, 2.3%, and 0.3%, respectively. There was a 7-fold difference in 2002 (South Dakota, 76.1 mg/100 persons; Delaware, 10.1 mg/100 persons). Relative to the average state in 2017, those reporting the highest values (Montana, 20.1; North Dakota, 24.1 mg/100 persons) were significantly elevated. Cocaine use within the Medicare and Medicaid programs was negligible. Cocaine use within the Geisinger system was rare from 2002 to 2007 (<4 orders/100 000 patients per year) but increased to 48.7 in 2018. Conclusion and Relevance: If these pharmacoepidemiological patterns continue, licit cocaine may soon become a historical relic. The pharmacology and pharmacotherapeutics education of health care providers may need to be adjusted accordingly.

Preoperative Use of Clopidogrel Does Not Affect Outcomes for Femoral Neck Fractures Treated With Hemiarthroplasty

BACKGROUND

The antiplatelet effect of clopidogrel on blood loss and perioperative complications after surgical intervention remains ambiguous. The purpose of this study was to determine if patients on clopidogrel before hemiarthroplasty for femoral neck fracture are predisposed to greater surgical bleeding and perioperative complications compared with those not taking clopidogrel before surgery.

METHODS

We conducted a review of our electronic medical record from 2006-2013 and identified 602 patients who underwent 623 hemiarthroplasty procedures for displaced femoral neck fracture, of which 54 cases (9%) were taking clopidogrel before hospital admission. Patient demographics and comorbidities, operative and surgical variables, and perioperative complications at 90 days were compared between the clopidogrel and nonclopidogrel user groups.

RESULTS

The 2 groups of patients had similar baseline characteristics, but patients taking clopidogrel preoperatively were sicker with higher American Society of Anesthesiologists scores (P = .049) and age-adjusted Charlson index (P = .001). They also had a greater incidence of cerebrovascular disease (P = .01), chronic obstructive pulmonary disease (P = .03), diabetes (0.03), and malignancy (P < .001). There was no significant difference between the 2 patient groups with respect to 90-day postoperative medical readmissions (P = .85), surgical readmissions (P = .26), infection (P = .99), and mortality (P = .89).

CONCLUSION

Patients taking clopidogrel who present with a displaced femoral neck fracture can safely undergo a hemiarthroplasty while actively on clopidogrel without an increase in medical or surgical complications and mortality. We do not recommend delaying surgical intervention until the antiplatelet effects of clopidogrel subside.

Potential of Nano-Formulated Zinc Oxide for Control of Citrus Canker on Grapefruit Trees

Antimicrobial activity of experimental formulations of two structurally different nano-zinc oxide materials, plate-like Zinkicide SG4 and particulate Zinkicide SG6, was evaluated against Xanthomonas citri subsp. citri, the cause of citrus canker. In vitro assay demonstrated Zinkicide SG4 had a twofold lower minimum inhibitory concentration (MIC) against Escherichia coli and X. alfalfae subsp. citrumelonis (62.5 to 250 µg/ml) compared with copper sulfate (250 µg/ml), copper hydroxide (250 to 500 µg/ml), or cuprous oxide/zinc oxide (125 to 250 µg/ml). Zinkicide SG6 had a sevenfold to eightfold lower MIC against Escherichia coli and X. alfalfae subsp. citrumelonis (31 to 250 μg/ml). Leaves of sweet orange (Citrus sinensis) and fruit of 'Ruby Red' grapefruit (C. paradisi) were evaluated for citrus canker disease control. A greenhouse assay with foliage demonstrated that spray treatment with Zinkicide reduced citrus canker lesion development after injection-infiltration of X. citri subsp. citri into the leaf intercellular space. In field trials conducted in Southeast Florida in 2014 and 2015, Zinkicide SG4 and SG6 reduction of grapefruit canker incidence exceeded that of cuprous oxide and cuprous oxide/zinc oxide bactericides. Zinkicide formulations were also effective against the fungal diseases, citrus scab (Elsinoe fawcetti) and melanose (Diaporthe citri), on grapefruit. No sign of phytotoxicity to the fruit rind was observed during either season. Antimicrobial activity of Zinkicide for protection of leaves and fruit against X. citri subsp. citri was comparable or exceeded that for commercial copper and zinc oxide formulations which may be attributed to translaminar movement of Zinkicide.

Clinical and economic consequences of statin intolerance in the United States: Results from an integrated health system

BACKGROUND

Although statins are considered safe and effective, they have been associated with statin intolerance (SI) in clinical and observational studies.

OBJECTIVE

The objective of this study was to describe the clinical and economic consequences of SI through comparison of an SI cohort of patients with matched controls.

METHODS

This study used data extracted from an integrated health system's electronic health records from 2008 to 2014. Adults with SI were matched to controls using a propensity score. Patients were hierarchically classified into 6 mutually exclusive cardiovascular (CV)-risk categories: recent acute coronary syndrome (ACS; ≤12 months preindex), coronary heart disease, ischemic stroke, peripheral artery disease, diabetes, or primary prevention. The study endpoints, low-density lipoprotein cholesterol (LDL-C) goal attainment, medical costs, and time to first CV event were compared using conditional logistic regression, generalized linear, and Cox proportional hazards models, respectively.

RESULTS

Patients with SI (n = 5190) were matched with controls (n = 15,570). Patients with SI incurred higher medical costs and were less likely to reach LDL-C goals than controls. Patients with SI were at higher risk for revascularization procedures in all CV risk categories except ACS, and those in the diabetes risk category were at higher risk for any CV event. There was a lower risk of all-cause death among patients with SI.

CONCLUSIONS

Patients with SI were less likely to reach LDL-C goals, incurred higher health care costs, and experienced a higher risk for nonfatal CV events than patients without SI. Alternative management strategies are needed to better treat high CV risk patients.

No association of labor epidural analgesia with cerebral palsy in children

BACKGROUND

Some pregnant women avoid labor epidural analgesia because of their concerns about risk of cerebral palsy in children. Although it is believed that labor epidural does not contribute to cerebral palsy, to our knowledge no study has been published to specifically address this concern. We carried out a retrospective case-control study to investigate whether labor epidural analgesia is associated with cerebral palsy in children.

METHODS

This study used data that were collected and entered into the Geisinger electronic health records between January 2004 and January 2013. During this period, 20,929 children were born at Geisinger hospitals. Among them, 50 children were diagnosed with cerebral palsy, and 20 of those were born vaginally. Each of these 20 cerebral palsy children was matched with up to 5 non-cerebral palsy children born at the same hospitals in the same timeframe using propensity scoring methods. Analgesia was classified as epidural (including epidural or combined spinal and epidural) or non-epidural. Conditional logistic regression was used to compare the percentages of deliveries with each analgesia type between the cerebral palsy and non-cerebral palsy groups.

RESULTS

In the non-cerebral palsy group, the percentage of patients receiving labor epidural analgesia was 72 %, and in the cerebral palsy group the percentage was 45 %. There was no significant difference between non-cerebral palsy and cerebral palsy groups (odds ratio, 0.57; 95 % confidence interval, 0.14-2.24; p = 0.42).

CONCLUSION

We found no association between the use of labor epidural analgesia and the occurrence of cerebral palsy in children.

Airborne Exposure of Methyl Methacrylate During Simulated Total Hip Arthroplasty and Fabrication of Antibiotic Beads

As the use of cement remains prevalent in orthopedic surgery, so do concerns over the safety of its active ingredient, methyl methacrylate (MMA). The Occupational Health and Safety Agency (OSHA) limits the airborne exposure to 100 parts per million (ppm) averaged over an 8 hour period. We measured MMA exposure to operating room personnel during simulated total hip arthroplasty (THA), antibiotic bead fabrication and simulated spill of MMA. Cumulative and peak exposures during simulated THA and antibiotic bead fabrication did not exceed OSHA limits of 100ppm. Vacuum mixing and greater distance from the vapor source reduced measured MMA exposure. Spilled MMA led to prolonged and elevated MMA levels. MMA levels returned to a negligible level in all scenarios by 20 minutes after mixing.

Abstract 146: Clinical and Economic Consequences of Statin Intolerance in the U.S.: Results from an Integrated Health System

Background: Low-density lipoprotein cholesterol (LDL-C) is a key therapeutic target for reducing risk of cardiovascular (CV) events. While statins are the mainstay of therapy due to efficacy and safety, observational studies indicate patients prescribed statins are unable to tolerate them to varying degrees. The study objective was to examine the clinical and economic consequences of statin intolerance (SI) comparing SI patients to non-SI patients on statin therapy.

Methods: This retrospective cohort study used data from an integrated health system’s electronic health record from 2009-2014. Adult patients diagnosed as statin intolerant (identified through a custom diagnosis code), with ≥ 6 months pre- and post-index date eligibility were considered for the study. All patients were hierarchically ordered into 6 mutually exclusive CV risk categories: recent acute coronary syndrome (ACS, < 12 months pre-index); coronary heart disease (CHD); ischemic stroke; peripheral artery disease (PAD); diabetes; or primary prevention. Index dates were defined as the SI diagnosis date for SI patients and a matched encounter date within ±90 days for controls. A total of 5,252 SI patients were matched to 15,756 non-SI statin users (1:3 ratio) using a propensity score that included CV risk, Charlson comorbidity index, and other clinical characteristics as covariates. Time to first myocardial infarction, unstable angina, coronary revascularization, ischemic stroke, and CV death were compared between groups using Kaplan-Meier plots and Cox proportional hazard models. Total medical costs and LDL-C goal attainment were compared using generalized linear models and conditional logistic regression, respectively.

Results: The mean age of the study population was 62 years with the majority being females (61%). Three percent were categorized as recent ACS, followed by 22% for CHD, 1% ischemic stroke, 5% PVD, 17% diabetes and 52% primary prevention patients. Before matching, 5% of statin users were deemed statin intolerant by their provider; although, 86% were still able to tolerate at least asymmetric statin dosing. Compared to the matched cohort, SI patients experienced significantly higher risk of unstable angina (hazard ratio (HR)=1.55, 95% CI=1.29-1.86) and revascularization procedures (HR=1.78, 95% CI=1.47-2.17) but lower risk of CV death (HR 0.42, 95% CI=0.33-0.55). Patients with statin intolerance also experienced higher costs (cost ratio=1.21, 95% CI=1.12, 1.29) and a higher risk of not achieving LDL-C goal (odds ratio=1.84, 95% CI=1.58-2.13). All p-values were <0.0001.

Conclusion: While the majority of SI patients were on a statin, SI patients demonstrate a higher risk of some cardiovascular events; incur higher healthcare costs; and difficulty reaching LDL-C goals compared to patients without SI. Alternative treatment strategies are needed to better serve this at-risk patient population.

Impact of chronic kidney disease stage on lower-extremity arthroplasty

End-stage renal disease and dialysis is commonly associated with poor outcomes after joint replacement surgery. The goal of this study was to evaluate postoperative complications in patients with less advanced chronic kidney disease undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA). Patients who underwent THA or TKA between 2004 and 2011 with stage 1, 2, or 3 chronic kidney disease were retrospectively reviewed via an electronic medical record. The authors compared 377 patients who had stage 1 to 2 chronic kidney disease with 402 patients who had stage 3 chronic kidney disease. No significant differences in 90-day readmission or revision rates were found between the stage 1 to 2 and stage 3 patient groups. For patients with stage 3 chronic kidney disease, the overall mortality rate was greater than that in patients with stage 1 to 2 chronic kidney disease. However, when adjusted for comorbid disease, no significant increases were seen in joint infection, readmission, or early revision between patients with stage 1 to 2 chronic kidney disease vs patients with stage 3 chronic kidney disease. The overall incidence of infection was high (3.5%) but far less than reported for patients with end-stage renal disease, dialysis, and kidney transplant. In conclusion, patients with stage 1, 2, or 3 chronic kidney disease may have a higher than expected rate of prosthetic joint infection (3.5%) after total joint arthroplasty. Patients with stage 3 chronic kidney disease are at higher risk for postoperative mortality compared with those with lesser stages of kidney disease.

Presymptomatic Fibrous Root Decline in Citrus Trees Caused by Huanglongbing and Potential Interaction with Phytophthora spp

Huanglongbing (HLB), associated with 'Candidatus Liberibacter asiaticus', was first detected in Florida in late 2005 and is now widely distributed throughout the commercial citrus-growing regions. In recent seasons, concurrent with freeze and drought episodes, symptomatic HLB-infected trees were much more affected by the extremes of temperature and moisture than trees without HLB. Symptoms exhibited by the stressed trees were excessive leaf loss and premature fruit drop even when HLB-infected trees were managed with good nutritional and irrigation practices recommended to support health of HLB-affected trees. This stress intolerance may be due to a loss of fibrous roots. To assess root status of HLB-infected trees on 'Swingle' citrumelo rootstock (Citrus paradisi × Poncirus trifoliata), blocks of 2,307 3-year-old 'Hamlin' orange trees and 2,693 4-year-old 'Valencia' orange trees were surveyed visually and with a real-time polymerase chain reaction (PCR) assay to determine 'Ca. L. asiaticus' infection status. The incidence of 'Ca. L. asiaticus'-infected trees (presymptomatic: 'Ca. L. asiaticus'+, visually negative; and symptomatic: 'Ca. L. asiaticus'+, visually positive) trees was 89% for the Hamlin block and 88% for the Valencia block. 'Ca. L. asiaticus'+ trees had 30 and 37% lower fibrous root mass density for presymptomatic and symptomatic trees, respectively, compared with 'Ca. L. asiaticus'- trees. In a second survey, 10- to 25-year-old Valencia trees on Swingle citrumelo or 'Carrizo' citrange (C. sinensis (L.) × P. trifoliata) rootstock were sampled within 3 to 6 months after identification of visual HLB status as symptomatic ('Ca. L. asiaticus'+, visually positive) or nonsymptomatic ('Ca. L. asiaticus'-, visually negative) in orchards located in the central ridge, south-central, and southwest flatwoods. Pairs of HLB symptomatic and nonsymptomatic trees were evaluated for PCR status, fibrous root mass density, and Phytophthora nicotianae propagules in the rhizosphere soil. 'Ca. L. asiaticus'+ trees had 27 to 40% lower fibrous root mass density and, in one location, higher P. nicotianae per root but Phytophthora populations per cubic centimeter of soil were high on both 'Ca. L. asiaticus'+ and 'Ca. L. asiaticus'- trees. Fibrous root loss from HLB damage interacted with P. nicotianae depending on orchard location and time of year.

Use of an integrated, anatomic-based, orthopaedic resident education curriculum: a 5-year retrospective review of its impact on orthopaedic in-training examination scores

INTRODUCTION

Experts have called for a comprehensive didactic curriculum in orthopaedic residency training. This study examined the effects of an anatomic-based, integrated conference program on annual Orthopaedic In-Training Examination (OITE) scores at a single orthopaedic residency program.

METHODS

We implemented a new, integrated, anatomic-based curriculum in January 2005. Differences between scores were analyzed by postgraduate year (PGY) of training. OITE scores (percentile ranking and raw scores) of year 1 (PGY-2) through year 4 (PGY-5) residents exposed to the curriculum (2005-2009) were compared to prior PGY-2 through PGY-5 residents (2000-2004) who had experienced the previous unstructured curriculum. To evaluate for cohort effects, United States Medical Licensing Examination (USMLE) Step I scores for these 2 groups were also compared.

RESULTS

Eight residents were exposed to the new conference program and 8 to the prior conference program. All residents' percentile rankings improved after exposure to the curriculum, although improvement was not statistically significant for all participants. The most dramatic improvements in OITE scores were seen for PGY-4 and PGY-5 residents, which improved from 65th to 91st percentile (P  =  .03) and from 66th to 91st percentile (P  =  .06), respectively. There were no differences between the cohorts in USMLE Step I scores.

DISCUSSION

Initiation of an integrated, anatomic-based, resident conference program had a positive impact on resident performance on the OITE.

Fatty Acid methyl ester profiles for characterization of glomalean fungi and their endomycorrhizae

Arbuscule-forming fungi in the order Glomales form obligate endomycorrhizal associations with plants that make them difficult to quantify, and taxonomy of the group is only beginning to be objectively understood. Fatty acid methyl ester (FAME) profiles were analyzed to assess the diversity and quantity of fatty acids in 53 isolates of 24 glomalean species. Spores and endomycorrhizal roots of sudan grass (Sorghum sudanense) and the citrus rootstock Carrizo citrange (Poncirus trifoliata x Citrus sinensis) were examined. Spores yielded reproducible FAME profiles from replicate spore collections extracted from soil pot cultures despite being grown in association with a host plant and with contaminating microorganisms present. Unweighted pair group analysis revealed relatively tight clusters of groups at the intraspecific, specific, and generic levels; however, lipid profiles at the family level were convergent. Thus, FAME profile comparisons provided a robust measure of similarity below the family level. FAME profiles in sudan grass roots containing vesicles and/or spores of Glomus intraradices were more similar to spore profiles than to profiles from nonmycorrhizal roots. The FAME profiles for Gigaspora species, which do not form vesicles or spores in roots, were less distinct from nonmycorrhizal roots. G. intraradices and G. rosea produced fatty acids in roots that were distinguishable from each other as well as from the host root. Production in citrus roots of the fatty acid 16:1(inf(omega)5) cis by two Glomus species was correlated with the development of mycorrhizal colonization as measured by clearing and staining procedures and by estimates of total incidence and vesicle intensity. FAME analysis of roots not only provided a measure of colonization development but also served as an index of carbon allocated to intraradical fungal growth and lipid storage.

Wind Speed Effects on the Quantity of Xanthomonas citri subsp. citri Dispersed Downwind from Canopies of Grapefruit Trees Infected with Citrus Canker

The epidemic of citrus canker (Xanthomonas citri subsp. citri) in Florida continues to expand since termination of the eradication program in 2006. Storms are known to be associated with disease spread, but little information exists on the interaction of fundamental physical and biological processes involved in dispersal of this bacterium. To investigate the role of wind speed in dispersal, wind/rain events were simulated using a fan to generate wind up to 19 m·s^-1 and spray nozzles to simulate rain. Funnels at ground level and panels at 1.3 m height and distances up to 5 m downwind collected wind-driven splash. Greater wind speeds consistently dispersed more bacteria, measured by concentration (colony forming units [CFU] ml^-1) or number sampled (bacteria flux density [BFD] = bacteria cm^-2 min^-1), from the canopy in the splash. The CFU ml^-1 of X. citri subsp. citri collected by panels 1 m downwind at the highest wind speed was up to 41-fold greater than that collected at the lowest wind speed. BFD at the highest wind speed was up to 884-fold higher than that collected at the lowest wind speed. Both panels at distances >1 m and funnels at distances >0 m collected many-fold more X. citri subsp. citri at higher wind speeds compared to no wind (up to 1.4 × 10³-fold greater CFU ml^-1 and 1.8 × 10⁵-fold the BFD). The resulting relationship between wind speed up to 19 m·s^-1 and the mean CFU ml^-1 collected by panel collectors downwind was linear and highly significant. Likewise, the mean CFU ml^-1 collected from the funnel collectors had a linear relationship with wind speed. The relationship between wind speed and BFD collected by panels was generally similar to that described for CFU ml^-1 of X. citri subsp. citri collected. However, BFD collected by funnels was too inconsistent to determine a meaningful relationship with increasing wind speed. The quantity of bacteria collected by panels declined with distance, and the relationship was described by an inverse power model (R² = 0.94 to 1.00). At higher wind speeds, more bacteria were dispersed to all distances. Windborne inoculum in splash in subtropical wet environments is likely to be epidemiologically significant, as both rain intensity and high wind speed can interact to provide conditions conducive for dispersing large quantities of bacteria from canker-infected citrus trees. Disease and crop management aimed at reducing sources of inoculum and wind speeds in a grove should help minimize disease spread by windborne inoculum.

Plant-pathogenic bacteria as biological weapons - real threats?

At present, much attention is being given to the potential of plant pathogens, including plant-pathogenic bacteria, as biological weapons/bioterror weapons. These two terms are sometimes used interchangeably and there is need for care in their application. It has been claimed that clandestine introduction of certain plant-pathogenic bacteria could cause such crop losses as to impact so significantly on a national economy and thus constitute a threat to national security. As a separate outcome, it is suggested that they could cause serious public alarm, perhaps constituting a source of terror. Legislation is now in place to regulate selected plant-pathogenic bacteria as potential weapons. However, we consider it highly doubtful that any plant-pathogenic bacterium has the requisite capabilities to justify such a classification. Even if they were so capable, the differentiation of pathogens into a special category with regulations that are even more restrictive than those currently applied in quarantine legislation of most jurisdictions offers no obvious benefit. Moreover, we believe that such regulations are disadvantageous insofar as they limit research on precisely those pathogens most in need of study. Whereas some human and animal pathogens may have potential as biological or bioterror weapons, we conclude that it is unlikely that any plant-pathogenic bacterium realistically falls into this category.

Cyber security risk assessment for SCADA and DCS networks

The growing dependence of critical infrastructures and industrial automation on interconnected physical and cyber-based control systems has resulted in a growing and previously unforeseen cyber security threat to supervisory control and data acquisition (SCADA) and distributed control systems (DCSs). It is critical that engineers and managers understand these issues and know how to locate the information they need. This paper provides a broad overview of cyber security and risk assessment for SCADA and DCS, introduces the main industry organizations and government groups working in this area, and gives a comprehensive review of the literature to date. Major concepts related to the risk assessment methods are introduced with references cited for more detail. Included are risk assessment methods such as HHM, IIM, and RFRM which have been applied successfully to SCADA systems with many interdependencies and have highlighted the need for quantifiable metrics. Presented in broad terms is probability risk analysis (PRA) which includes methods such as FTA, ETA, and FEMA. The paper concludes with a general discussion of two recent methods (one based on compromise graphs and one on augmented vulnerability trees) that quantitatively determine the probability of an attack, the impact of the attack, and the reduction in risk associated with a particular countermeasure.

Protection of Citrus Rootstocks Against Phytophthora spp. with a Hypovirulent Isolate of Phytophthora nicotianae

ABSTRACT Phytophthora root rot of citrus in Florida is caused by Phytophthora nicotianae and P. palmivora. A naturally occurring isolate of P. nicotianae (Pn117) was characterized as hypovirulent on citrus roots. Pn117 infected and colonized fibrous roots, but caused significantly less disease than the virulent isolates P. nicotianae Pn198 and P. palmivora Pp99. Coincident inoculation of rootstock seedlings of Cleopatra mandarin (Citrus reticulata) or Swingle citrumelo (C. paradisi x Poncirus trifoliata) with the hypovirulent Pn117 and the virulent isolates Pn198 and Pp99 did not reduce the severity of disease caused by the virulent Phytophthora spp. When either rootstock was inoculated with the hypovirulent Pn117 for 3 days prior to inoculation with virulent isolates, preinoculated seedlings had significantly less disease and greater root weight compared with seedlings inoculated with the virulent isolates alone. Recovery of the different colony types of Phytophthora spp. from roots of sweet orange (C. sinensis) or Swingle citrumelo was evaluated on semiselective medium after sequential inoculations with the hypovirulent Pn117 and virulent Pp99. Pn117 was isolated from roots at the same level as the Pp99 at 3 days post inoculation. Preinoculation of Pn117 for 3 days followed by inoculation with Pp99 resulted in greater recovery of the hypovirulent isolate and lower recovery of the virulent compared with coincident inoculation.

Food web responses to augmenting the entomopathogenic nematodes in bare and animal manure-mulched soil

Factorial treatments of entomopathogenic nematodes (EPN) and composted, manure mulches were evaluated for two years in a central Florida citrus orchard to study the post-application biology of EPN used to manage the root weevil, Diaprepes abbreviatus. Mulch treatments were applied once each year to study the effects of altering the community of EPN competitors (free-living bactivorous nematodes) and antagonists (nematophagous fungi (NF), predaceous nematodes and some microarthro-pods). EPN were augmented once with Steinernema riobrave in 2004 and twice in 2005. Adding EPN to soil affected the prevalence of organisms at several trophic levels, but the effects were often ephemeral and sometimes inconsistent. EPN augmentation always increased the mortality of sentinel weevil larvae, the prevalence of free-living nematodes in sentinel cadavers and the prevalence of trapping NF. Subsequent to the insecticidal effects of EPN augmentation in 2004, but not 2005, EPN became temporarily less prevalent, and fewer sentinel weevil larvae died in EPN-augmented compared to non-augmented plots. Manure mulch had variable effects on endoparasitic NF, but consistently decreased the prevalence of trapping NF and increased the prevalence of EPN and the sentinel mortality. Both temporal and spatial abundance of NF were inversely related to the prevalence of Steinernema diaprepesi, whereas Heterorhabditis zealandica prevalence was positively correlated with NF over time. The number of weevil larvae killed by EPN was likely greatest in 2005, due in part to non-target effects of augmentation on the endemic EPN community in 2004 that occurred during a period of peak weevil recruitment into the soil.

Feature and knowledge based analysis for reduction of false positives in the computerized detection of masses in screening mammography

Previously we presented a morphologic concentric layered (MCL) algorithm for the detection of masses in screening mammograms. The algorithm achieved high sensitivity (92%) but it also generated 3.26 false positives (FPs) per image. In the present study we propose a false positive reduction strategy based on using an artificial neural network that merges feature and knowledge-based analysis of suspicious mammographic locations. The ANN integrates two types of information regarding the suspicious candidates: (i) directional and fractal neighborhood analysis features, and (ii) knowledge-based analysis using an information-theoretic similarity metric. The study hypothesis is that the synergistic application of feature and knowledge-based analysis will be an effective strategy to reduce false positives while still maintaining sufficiently the detection rate for true masses. The study was performed using mammograms from the Digital Database of Screening Mammography. Using the fusion ANN decision strategy 56% of the FPs were reduced while maintaining 95% of the true masses.

Quantitative real-time polymerase chain reaction for bacterial enumeration and allelic discrimination to differentiate xanthomonas strains on citrus

ABSTRACT Quantitative real-time polymerase chain reaction (QRT-PCR) was developed for identification and enumeration of bacteria in citrus plant samples infected with Xanthomonas axonopodis pvs. citri and citrumelo, the cause of citrus bacterial canker (CBC) and citrus bacterial spot (CBS), respectively. Three sets of primers based on the pathogenicity gene (pth) in X. axonopodis pv. citri, a ribosomal gene in X. axonopodis pv. citrumelo, and the leucine-responsive regulatory protein (lrp) in both pathovars were combined with TaqMan probes and applied for specific strain detection and quantification. Calibration curves for bacterial abundance in plant samples obtained with the three primer-probe combinations were congruent with colony counts on plates of semiselective medium in most of the cases. However, apparent overestimation of bacterial cells by QRT-PCR indicated the presence of nonculturable or nonviable cells in some samples. In addition to quantification, the lrp primers and probes permitted differentiation by allelic discrimination of Xanthomonas strains infecting citrus tissues. This technique is based on the utilization of two probes that detect a single nucleotide difference in the target sequence between different strains and was validated with a collection of cultured Xanthomonas strains as well as tissue with CBC and CBS lesions. Allelic discrimination is demonstrated to be a more specific and sensitive protocol than previously developed PCR-based methods for strain identification and quantification.

Screening Triploid Hybrids of 'Lakeland' Limequat for Resistance to Citrus Canker

Resistance of citrus genotypes to Xanthomonas axonopodis pv. citri, the cause of Asiatic citrus canker (ACC), was evaluated by injection infiltration of 10³ and 10⁴ CFU/ml through stomates on the abaxial surface of immature leaves. Citrus genotypes for screening comprised two autotetraploids and nine triploid hybrids of 'Lakeland' limequat (Citrus aurantifolia × Fortunella japonica) and their progenitors ('Lakeland' limequat, the autotetraploids 'Femminello' lemon (Citrus limon) and 'Giant Key' lime (C. aurantifolia), and the somatic hybrids 'Key' [also known as 'Mexican'] lime + 'Valencia' orange and 'Hamlin' orange + 'Femminello' lemon). 'Meiwa' kumquat (Fortunella crassifolia) and 'Pineapple' sweet orange (C. sinensis) were used as known resistant and susceptible standards, respectively. Lesion number per inoculation site and bacterial population per lesion were recorded 15 to 19 days after inoculation. The assay was performed four times during a spring-summer-fall period under greenhouse conditions. Canker lesions were consistently produced by stomatal inoculation with 10⁴ but not 10³ CFU/ml. Susceptible and resistant genotypes were separated based on lesion number per inoculation site and bacterial population per lesion. Spearman's rank correlation analysis for lesion numbers on 15 genotypes common to all four assays showed significant correlations among the genotype rankings. Genotype rankings were also significantly correlated between the two bacterial population assays. Lesion number per inoculation site is sufficient for assessment of resistance of citrus genotypes to ACC without the necessity of conducting bacterial population assays. 'Lakeland' limequat is a promising seed parent for breeding acid citrus fruit that is resistant to ACC.

Lack of Control of Citrus Canker by Induced Systemic Resistance Compounds

Induced systemic resistance compounds (ISRs), acibenzolar-S-methyl (Actigard), and harpin protein (Messenger) were assayed in the greenhouse against Xanthomonas axonopodis pv. citrumelo, the cause of citrus bacterial spot (CBS), and X. axonopodis pv. citri, the cause of Asiatic citrus canker. Actigard and Messenger applied as foliar sprays 3 to 7 days before inoculation reduced numbers of lesions when either bacterium at 10³ or 10⁴ CFU/ml was injection-infiltrated into Swingle citrumelo leaves. Based on this activity, the ISRs were evaluated in southern Brazil in orchards of sweet oranges with low to moderate canker disease incidence in spray programs with and without copper oxychloride (COC) and copper hydroxide (CuOH). Actigard and Messenger were applied full season or in the first two or three sprays of a six-spray program in an attempt to reduce early canker disease on foliage and thereby reduce subsequent fruit infection and premature drop. Sprays of COC and CuOH were moderately to highly effective in reducing canker disease incidence and preventing premature fruit drop. Actigard or Messenger in combination with COC and CuOH, respectively, did not significantly reduce citrus canker incidence on foliage or fruit drop compared with Cu alone. The lack of additional control with ISRs means they cannot be recommended at this time to augment Cu programs for management of citrus canker.

Incidence of Endemic Entomopathogenic Nematodes Following Application of Steinernema riobrave for Control of Diaprepes abbreviatus

Control of Diaprepes abbreviatus by endemic and exotic entomopathogenic nematodes (EPN) was monitored during 2000-2001 in two citrus orchards in central Florida (Bartow and Poinciana). Caged sentinel insect larvae were buried beneath citrus trees for 7 days at 1 to 2-month intervals from April to October each year. At Bartow, the survey occurred in experimental plots that were (i) not treated with commercial EPN, (ii) treated twice annually since 1998 with commercially formulated Steinernema riobrave, or (iii) treated twice annually with S. riobrave and liquid fertilization (15 times/year) occurred in place of dry fertilizer (3 times/year) used in the other treatments. Four endemic EPN species, in addition to S. riobrave, were recovered from the sandy soil at Bartow: S. diaprepesi, Heterorhabditis zealandica, H. indica, and H. bacteriophora. Mean insect mortality in control plots was 39.4% (range = 13% to 74%), with seasonal maxima in May to July each year. Endemic EPN were recovered from 55% (range = 22% to 81%) of the cadavers each month. Total numbers of endemic EPN recovered in all plots during 2 years were directly related to the numbers of adult weevils (D. abbreviatus and Pachnaeus litus) captured in modified Tedder's traps and inversely related to recovery of S. riobrave. Insect mortality was higher and cadavers containing endemic EPN were more numerous in untreated control plots than in S. riobrave-treated plots, except during months in which S. riobrave was applied. In treated plots, endemic EPN were recovered from cadavers at twice the rate of S. riobrave. Suppression of endemic EPN in plots treated with S. riobrave, combined with inferior persistence by the introduced species, may have attenuated the net efficacy of S. riobrave against D. abbreviatus. In contrast, H. indica was the only endemic nematode recovered from the sandy clay loam soil at Poinciana, where the average mortality of D. abbreviatus was 12% (range 3% to 20%) and incidence of H. indica did not exceed 8%. Results of these surveys suggest that the regional patterns in the abundance and damage to citrus caused by D. abbreviatus in Florida are regulated by endemic EPN and other soilborne enemies of the weevil.

Tylenchulus semipenetrans Alters the Microbial Community in the Citrus Rhizosphere

Infection of citrus seedlings by Tylenchulus semipenetrans was shown to reduce subsequent infection of roots by Phytophthora nicotianae and to increase plant growth compared to plants infected by only the fungus. Hypothetical mechanisms by which the nematode suppresses fungal development include nutrient competition, direct antibiosis, or alteration of the microbial community in the rhizosphere to favor microorganisms antagonistic to P. nicotianae. A test of the last hypothesis was conducted via surveys of five sites in each of three citrus orchards infested with both organisms. A total of 180 2-cm-long fibrous root segments, half with a female T. semipenetrans egg mass on the root surface and half without, were obtained from each orchard site. The samples were macerated in water, and fungi and bacteria in the suspensions were isolated, quantified, and identified. No differences were detected in the numbers of microorganism species isolated from nematode-infected and uninfected root segments. However, nematode-infected root segments had significantly more propagules of bacteria at all orchard sites. Bacillus megaterium and Burkholderia cepacia were the dominant bacterial species recovered. Bacteria belonging to the genera Arthrobacter and Stenotrophomonas were encountered less frequently. The fungus community was dominated by Fusarium solani, but Trichoderma, Verticillum, Phythophthora, and Penicillium spp. also were recovered. All isolated bacteria equally inhibited the growth of P. nicotianae in vitro. Experiments using selected bacteria, T. semipenetrans, and P. nicotianae, alone or in combination, were conducted in both the laboratory and greenhouse. Root and stem fresh weights of P. nicotianae-infected plants treated with T. semipenetrans, B. cepacia, or B. megaterium were greater than for plants treated only with the fungus. Phytophthora nicotianae protein in roots of fungus-infected plants was reduced by nematodes (P </= 0.001), either alone or in combination with either bacterium. However, treatment with bacteria did not affect P. nicotianae development in roots. The results suggest different mechanisms by which T. semipenetrans, B. cepacia, and B. megaterium may mitigate virulence of P. nicotianae.

Phytophthora-Diaprepes Weevil Complex: Phytophthora spp. Relationship with Citrus Rootstocks

Diaprepes abbreviatus (Coleoptera: Curculionidae) is a root weevil, introduced from the Caribbean Basin into Florida in 1964. The larval stage feeds on fibrous and structural roots of citrus, predisposing the injured root system to infection and girdling by Phytophthora spp. In citrus orchards, the rootstocks trifoliate orange (Poncirus trifoliata) and hybrid 'Swingle' citrumelo (Citrus paradisi × P. trifoliata) are resistant to the complex of P. nicotianae with D. abbreviatus, while 'Cleopatra' mandarin (C. reticulata) is susceptible to this complex. When Phytophthora palmivora is coincident with P. nicotianae in fine-textured, poorly drained soils, Swingle citrumelo is more vulnerable to attack by the complex with P. palmivora than is Cleopatra mandarin. Infestation of 9-month-old seedlings with zero, two, or five neonate larvae resulted in a wide range of fibrous root and taproot damage of trifoliate orange and Cleopatra mandarin. Leakage of reducing sugars increased sharply as injury to the roots exceeded 75%. The relationship between feeding damage and root leakage was similar for the two rootstocks. Thus, reduced root damage was not based on host resistance to larval feeding. Root infection and rhizosphere populations of P. nicotianae were higher on Cleopatra mandarin than on trifoliate orange. Root rot by P. nicotianae did not increase with severity of feeding injury on either rootstock. Root infection and root rot by P. palmivora was more severe on trifoliate orange than on Cleopatra mandarin and increased with severity of larval damage. P. palmivora infected and rotted the taproot of both rootstocks if predisposed by larval feeding, but P. nicotianae did not. Commercial rootstocks are severely damaged by larvae of D. abbreviatus; therefore, tolerance of the Phytophthora-Diaprepes weevil complex should be based on resistance of rootstocks to each Phytophthora sp.

Infection of Citrus Roots by Tylenchulus semipenetrans Reduces Root Infection by Phytophthora nicotianae

Bioassays and whole-plant experiments were conducted to investigate the interaction between Tylenchulus semipenetrans and Phytophthora nicotianae. Both organisms are parasites of the citrus fibrous root cortex. Nematode-infected and non-infected root segments were excised from naturally infected field roots and placed on water agar in close proximity to agar plugs of P. nicotianae and then transferred to a Phytophthora-selective medium. At 10 and 12 days, 50% fewer nematode-infected segments were infected by P. nicotianae than non-infected segments. In whole-plant experiments in glass test tubes, sour orange seedlings were inoculated with two densities (8,000 or 80,000 eggs and second-stage juveniles) of T. semipenetrans, and after establishment of infection were inoculated with two densities (9,000 and 90,000 zoospores) of P. nicotianae. In the first experiment, fungal protein was 53% to 65% lower in the roots infected by both organisms than in roots infected by the fungus only. Compared to plants infected only by P. nicotianae, shoot weights were 33% to 50% greater (P </= 0.05) in plants infected by both parasites, regardless of inoculum density. Fibrous and tap root weights were 5% to 23% and 19% to 34% greater (P </= 0.05), respectively, in nematode-fungus combination treatments compared to the fungus alone. A second experiment was conducted, where plants were infected by the fungus, the nematode, both organisms, or neither organism. The soil mixture pH for 50% of the plants was adjusted from 4.5 to 7.0 to favor nematode infection. A higher rate of nematode infection of plants growing at pH 7.0 compared to pH 4.5 resulted in greater suppression of fungal development and greater inhibition of fungal damage to the plant. Compared to plants infected only by P. nicotianae, shoot and root weights were 37% and 33% greater (P </= 0.05), respectively, in plants infected by both parasites. These experiments have revealed antagonism between T. semipenetrans and P. nicotianae in citrus.

Eggs of Tylenchulus semipenetrans Inhibit Growth of Phytophthora nicotianae and Fusarium solani in vitro

In previous greenhouse and laboratory studies, citrus seedlings infested with the citrus nematode Tylenchulus semipenetrans and later inoculated with the fungus Phylophthora nicotianae grew larger and contained less fungal protein in root tissues than plants infected by only the fungus, demonstrating antagonism of the nematode to the fungus. In this study, we determined whether eggs of the citrus nematode T. semipenetrans and root-knot nematode Meloidogyne arenaria affected mycelial growth of P. nicotianae and Fusarium solani in vitro. Approximately 35,000 live or heat-killed (60 degrees C, 10 minutes) eggs of each nematode species were surface-sterilized with cupric sulfate, mercuric chloride, and streptomycin sulfate and placed in 5-pl drops onto the center of nutrient agar plates. Nutrient agar plugs from actively growing colonies of P. nicotianae or F. solani were placed on top of the eggs for 48 hours after which fungal colony growth was determined. Live citrus nematode eggs suppressed mycelial growth of P. nicotianae and F. solani (P </= 0.05) compared to heat-killed eggs and water controls. Reaction of the fungi to heat-killed eggs was variable. Root-knot nematode eggs had no effect on either P. nicotianae or F. solani mycelial growth. The experiment demonstrated a species-specific, direct effect of the eggs of the citrus nematode on P, nicotianae and F. solani.

Genetic relationship among worldwide strains of Xanthomonas causing canker in citrus species and design of new primers for their identification by PCR

Partial sequence analysis of the ribosomal operon in Xanthomonas axonopodis allowed discrimination among strains causing the A, B, and C types of citrus bacterial canker (CBC) and quantification of the relationship of these organisms with other species and pathovars in the same genus. Sets of primers based on sequence differences in the internally transcribed spacer and on a sequence from the plasmid gene pthA involved in virulence were designed for specific identification of xanthomonads causing CBC diseases. The two sets were validated with a collection of Xanthomonas strains associated with citrus species. The primer set based on ribosomal sequences had a high level of specificity for X. axonopodis pv. citri, whereas the set based on the pthA gene was universal for all types of CBC organisms. Moreover, the relationships among worldwide Xanthomonas strains causing CBC were analyzed by amplification of repetitive sequences (enterobacterial repetitive intergenic consensus and BOX elements). Under specific conditions, pathotypes of these Xanthomonas strains could be discerned, and subgroups of the pathotypes were identified. Subgroups of strains were associated with certain geographic areas of the world, and on this basis the origin of type A strains introduced into Florida could be inferred.

Quantitative PCR method for diagnosis of citrus bacterial canker

For diagnosis of citrus bacterial canker by PCR, an internal standard is employed to ensure the quality of the DNA extraction and that proper requisites exist for the amplification reaction. The ratio of PCR products from the internal standard and bacterial target is used to estimate the initial bacterial concentration in citrus tissues with lesions.

Growth and developmental stability of Drosophila melanogaster in low frequency magnetic fields

Magnetic fields (60 Hz) of 1.5 and 80 microT caused a significant reduction in the weight of Drosophila melanogaster. Moreover, fruit flies in an 80 microT field showed lower developmental stability than either those in a 0 or 1.5 microT field. Developmental instability was measured by fluctuating asymmetry and frequency of phenodeviants. More of the flies in the 80 microT field had fused abdominal segments, and they were more asymmetrical for wing vein R(4+5). The flies in the 1.5 microT field actually showed greater developmental stability than the control flies. Fewer of them had fused abdominal segments, and they were more symmetrical for wing vein R(4+5). Thus, at low field strengths, flies are more developmentally stable than control flies, even though they weigh less.

Larval growth of Diaprepes abbreviatus (Coleoptera: Curculionidae) and resulting root injury to three citrus varieties in two soil types

Larval growth and intraspecific competition of Diaprepes abbreviatus (L.) larvae and consequent root injury in container-grown citrus in the greenhouse were evaluated. Roots of Carrizo citrange, Citrus sinesis L. Osbeck x Poncirus trifoliata (L.) Raf.; Cleopatra mandarin, C. reticulata Blanco, and Swingle citrumelo, C. paradisi Macf. x P. trifoliata (L.) Raf. rootstock seedlings grown in Candler fine sand and potting soil were colonized with different populations of D. abbreviatus larvae. Larvae were exposed to the seedlings for 79 d. Larval growth and development increased steadily for approximately 70 d on all rootstock-soil combinations, at which time most larvae were instars 6-8. Most feeding injury occurred to roots when larvae were between instars 3 and 6. Larval weight reached a plateau at approximately 70 d, but often declined between 70 and 79 d. When larvae were small, injury to seedlings developed slowly, primarily on fibrous roots, then feeding increased rapidly, often resulting in total consumption of both fibrous root and bark tissue. Although not statistically significant, root injury developed slightly slower on Swingle citrumelo compared with Carrizo and Cleopatra rootstocks, but damage was comparable by 79 d. Little or no difference in consumptive benefit to the larvae was found between the rootstocks. Based on larval weight days, little feeding injury occurred during the first 21 d, but increased rapidly between 21 and 60 d. Soil type affected the rate of larval growth and development, with potting soil contributing to greater growth rates. Detritus in potting soil provided little or no nutritional resource, suggesting that the effect of potting soil on larval development was primarily physical. In addition, fewer inoculated larvae per seedling exhibited greater weight gains than higher infestation densities, suggesting that intraspecific competition for nutritional resources influenced larval development.

Phytophthora Brown Rot of Citrus: Temperature and Moisture Effects on Infection, Sporangium Production, and Dispersal

Sporadic epidemics of Phytophthora brown rot occur in citrus orchards in Florida and are caused primarily by Phytophthora palmivora and secondarily by P. nicotianae. With P. palmivora, fruit wetness durations of 3 h or more resulted in maximum infection at favorable temperatures. The optimum temperature range for fruit infection and brown rot development was 27 to 30°C. No brown rot developed at 22°C or less. The optimum temperature for sporulation in culture and on the fruit surface was 24°C, with sporangium production decreasing rapidly at higher or lower temperatures. A few sporangia were produced with 18 h of fruit wetness, and numbers increased as duration of wetness increased up to 72 h. Propagules were splash-dispersed by single droplets of water from infested peel disks horizontally about 350 to 450 mm and vertically about 30 to 45 mm with most isolates. Sporangia were not dispersed by air currents alone. Few sporangia of P. nicotianae were produced on fruit surfaces, and they were not readily dispersed by falling water droplets. Brown rot caused by P. palmivora can become epidemic in Florida from July to October during the rainy season because of its high temperature optimum and prolific sporulation on the fruit surface.

Developmental Instability as a Means of Assessing Stress in Plants: A Case Study Using Electromagnetic Fields and Soybeans

Developmental instability is often assessed using deviations from perfect bilateral symmetry. Here, we review the literature describing previous studies, suggest mechanisms that may account for both the generation and disruption of bilateral symmetry, and examine the influence of electromagnetic fields on the asymmetry of soybean leaves. Leaves from plants under high-voltage power lines generating pulsed magnetic fields of <3 to >50 mG were more asymmetrical for two parameters (the terminal leaflet widths and lateral rachilla lengths) than leaves of plants even 50 or 100 m away from power lines. This asymmetry could not be attributed to either size scaling or measurement error.

Characterization of Phytophthora spp. Causing Outbreaks of Citrus Brown Rot in Florida

ABSTRACT Epidemics of citrus brown rot from 1994 to 1997 in the south-central and east-coast citrus areas of Florida were characterized and the causal Phytophthora spp. identified. Two species of Phytophthora, P. palmivora and P. nicotianae, were consistently associated with brown rot. Epidemics caused by P. palmivora appeared to be initiated on immature fruit dropped on the orchard floor. The soilborne fungus infected and sporulated on these fruit and was then disseminated to fruit above 1 m in the canopy. In contrast, infection by P. nicotianae, the common cause of root rot, was confined to the lowest 1 m of the canopy. Fruit infected by P. palmivora produced large amounts of ellipsoidal sporangia available for splash dispersal, whereas those infected by P. nicotianae produced far fewer spherical sporangia. Isolates from brown rot epidemics were compared with P. nicotianae from citrus in Florida and Texas, P. citrophthora in California, P. palmivora, and selected Phytophthora spp. from other hosts. Brown rot symptoms produced by the different pathogenic citrus isolates on inoculated fruit were indistinguishable. Morphology, mating behavior, and isozyme patterns of brown rot isolates from 1988 to 1997 matched P. palmivora from citrus roots, other host plants, and other locations, but were different from characterized isolates of P. citrophthora in California and P. nicotianae in Florida and Texas. Cellulose acetate electrophoresis of the isozyme glucose-6-phosphate isomerase rapidly identified the causal citrus pathogen from infected fruit and soil isolation plates. Although P. palmivora is an aggressive pathogen of citrus roots, bark, and fruit, populations in orchard soils were low compared with P. nicotianae.

Composted Municipal Waste Reduces Infection of Citrus Seedlings by Phytophthora nicotianae

Most citrus nurseries and orchards in Florida are infested with Phytophthora nicotianae, the causal agent of Phytophthora root rot. Although fungicides control the disease and increase seedling growth and tree yields, they are not always economically or environmentally sustainable. Amendment of citrus soils with composted municipal waste (CMW) may provide an alternative to fungicides for disease management. Citrus seedling growth decreased with increasing proportions of one CMW source, indicating the potential for phytotoxicity from soluble salts and acetic acid when the proportion of CMW in soil exceeded 20% (vol/vol). When a citrus soil was amended (20% vol/vol) with certain sources of CMW, the incidence of infection of 5-week-old susceptible citrus seedlings by P. nicotianae was reduced from 95% to as low as 5%. Addition of fresh CMW to two different citrus soils reduced colony growth of P. nicotianae after the fungus was incubated in the amended soil for 6 days and then recovered on PARPH selective medium. If CMW was stored for more than 3 months before amendment, the soil mixtures did not suppress colony development. In general, extracts of fresh CMW reduced mycelial growth in vitro; whereas suppressiveness of CMW from the same batch was lost after storage. Acetic acid was detected at higher concentration in fresh CMW that suppressed colony growth than in CMW that lacked activity. A species of Acremonium was isolated from another source of CMW that was suppressive to P. nicotianae. This fungus parasitized hyphae of P. nicotianae in vitro. Thus, CMWs have the potential to at least temporarily suppress P. nicotianae through chemical and microbial agents depending on source and age of the CMW.

Nematode Community Composition under Various Irrigation Schemes in a Citrus Soil Ecosystem

Interest in the sustainability of farming practices has increased in response to environmental problems associated with conventional agricultural management often adopted for the production of herbaceous crops, ornamentals, and fruit crops. Availability of measures of the status of the soil ecosystem is of immediate importance, particularly for environmental assessment and monitoring programs. This study investigated the effects of various irrigation regimes (an example of an agricultural management practice) on the structure of the nematode fauna in a citrus orchard in the sandy ridge area of Central Florida. Ecological measures such as community structure indices, diversity indices, and maturity indices were assessed and related to irrigation intensity. Maturity index was an effective measure in distinguishing differences between irrigation regimes, whereas other indices of community structure were not. Of various nematode genera and trophic groups, only omnivores and the omnivore genera. Aporcelaimellus and Eudorylaimus responded to irrigation treatments.

Histological Comparison of Fibrous Root Infection of Disease-Tolerant and Susceptible Citrus Hosts by Phytophthora nicotianae and P. palmivora

ABSTRACT Phytophthora nicotianae and P. palmivora infect and cause rot of fibrous roots of susceptible and tolerant citrus rootstocks in Florida orchards. The infection and colonization by the two Phytophthora spp. of a susceptible citrus host, sour orange (Citrus aurantium), and a tolerant host, trifoliate orange (Poncirus trifoliata), were compared using light and electron microscopy. Penetration by both Phytophthora spp. occurred within 1 h after inoculation, regardless of the host species. No differences were observed in mode of penetration of the hypodermis or the hosts' response to infection. After 24 h, P. palmivora had a significantly higher colonization of cortical cells in susceptible sour orange than in tolerant trifoliate orange. Intracellular hyphae of both Phytophthora spp. were observed in the cortex of sour orange, and cortical cells adjacent to intercellular hyphae of P. palmivora were disrupted. In contrast, the cortical cells of sour orange and trifoliate orange adjacent to P. nicotianae hyphae and the cortical cells of trifoliate orange adjacent to P. palmivora were still intact. After 48 h, the cortical cells of both hosts adjacent to either Phytophthora spp. were disrupted. After 48 and 72 h, P. palmivora hyphae colonized the cortex of sour orange more extensively than the cortex of trifoliate orange; P. palmivora also colonized both hosts more extensively than P. nicotianae. A higher rate of electrolyte leakage among host-pathogen combinations reflected the combined effects of greater cell disruption by P. palmivora than by P. nicotianae, and the higher concentration of electrolytes in healthy roots of trifoliate orange than of sour orange. Although cellular responses unique to the tolerant host were not observed, reduced hyphal colonization by both pathogens in the cortex of trifoliate orange compared with sour orange is evidence for a putative resistance factor(s) in the trifoliate orange roots that inhibits the growth of Phytophthora spp.

Metalaxyl-Resistant Isolates of Phytophthora nicotianae: Occurrence, Sensitivity, and Competitive Parasitic Ability on Citrus

Phytophthora nicotianae was recovered from 8 of 11 nursery sites, and metalaxyl-resistant isolates were detected at 6 of the 8 positive sites. Resistant isolates comprised 31 to 59% of the population at those sites. Most resistant isolates grew well in the presence of 100 μg/ml of metalaxyl, whereas sensitive isolates did not grow at 1.0 μg/ml. Some isolates from mature citrus groves were intermediate in their sensitivity. Metalaxyl-drench treatments failed to control resistant isolates in greenhouse tests, but fosetyl-Al was usually effective. The replacement series technique was used to compare the relative competitive ability of resistant and sensitive isolates in greenhouse tests. Results varied according to the isolate used, but at least some metalaxyl-resistant isolates were able to compete favorably with sensitive isolates in the absence of metalaxyl. In a field test, a high percentage of the population remained resistant to metalaxyl even after 2.5 years without treatment with this fungicide. Excessive use of metalaxyl in nursery situations has reduced the future utility of the product in Florida citrus groves.

HMB45 negative spindle cell malignant melanoma

Desmoplastic malignant melanoma (DMM) and spindle cell malignant melanoma (SCMM) form a continuum without a discrete separation. One feature characteristic of DMM is a negative reaction for HMB45, a marker for premelanosomes. Fifty-six cases of SCMM were stained with HMB45. The clinical features, histologic features, and survival data for HMB45(+) and HMB45(-) SCMM were compared. Thirty cases were HMB45(-), and 26 were HMB45(+). In the HMB45(-) cases, there was a 1.4:1 ratio of males to females, and in the HMB45(+) cases the ratio was 1:1.5. Only 12.9% of the HMB45(-) cases occurred on the trunk compared with 40% of the HMB45(+) cases. The average ages for the HMB45(-) and the HMB45(+) cases were 65.6 and 61 years, respectively. Follow-up was obtained on 22 cases: 11 HMB45(-) and 11 HMB45(+). Of the 11 HMB45(-) cases, four had a 5-year disease-free survival. Of the 11 HMB45(+) cases, only one had a 5-year disease free survival. HMB45(-) SCMM appear to have a less aggressive biologic potential than HMB45(+) SCMM.

Merkel cell carcinoma: analysis of clinical, histologic, and immunohistologic features of 132 cases with relation to survival

BACKGROUND

Merkel cell carcinoma (MCC) is an uncommon malignancy of the skin and has a high rate of recurrence and metastasis. There have been few large studies of the biologic behavior of MCC.

OBJECTIVE

Our purpose was to determine whether there were clinical or histologic features of MCC that predict its biologic behavior.

METHODS

We reviewed 132 cases of MCC. Clinical and histologic features were correlated with follow-up information to determine whether any of these were associated with prognosis.

RESULTS

Clinical information was available on 126 patients; 57 were alive, 1 was alive with tumor, 28 died of tumor, 27 died from other causes, and 14 were lost to follow-up. MCC on the buttock/thigh area or trunk had the worst prognosis, and those on the distal extremities had the best prognosis; however, the difference was not statistically significant. Sex and age were not significant factors. Small cell size, high mitotic rate, and large tumor size were associated with a low survival rate. When cell size was excluded, male sex and depth of invasion were associated with a worse survival, although these were not statistically significant.

CONCLUSION

Cell size, mitotic rate, and tumor size are significant factors in relation to the biologic behavior of MCC.

The Influence of Spray Adjuvants on Exacerbation of Citrus Bacterial Spot

The effect of adjuvants on the spread of Xanthomonas axonopodis pv. citrumelo applied to nursery plots of citrus (Citrus spp.) rootstock trees in simulated wind-blown rain was studied. Commercial adjuvants tested included a penetrant-surfactant, the penetrant or surfactant components of the penetrant-surfactant alone, an antitranspirant, a surfactant, or 1 of 3 formulations of a spreader-binder. Individual rows were treated with the adjuvants or water alone as a control. Bacterial dispersal gradients in all rows were similar and extended the entire 7 m of the nursery rows. Disease incidence, number of lesions per plant, and lesion diameters were determined at selected assay points in each row 28 days after the event. The penetrant-surfactant and its surfactant component significantly increased the total number of lesions per plant and mean lesion diameters compared to the water control. The disease gradient slopes associated with the penetrant-surfactant and its surfactant component were significantly flatter and more extensive than the water control. The penetrant component of the penetrant-surfactant, the antitranspirant, and two spreader-binders adjuvants did not significantly alter the disease gradient compared to the water control. Lesion sizes and numbers were also increased by a surfactant product and the surfactant component of the penetrant-surfactant, but not by the penetrant component of the penetrant-surfactant, the antitranspirant, or the three spreader-binder formulations. These results suggest that surfactants which induce stomatal flooding may enhance infection and exacerbate citrus bacterial epidemics.