Human immunomodulatory ligand B7-1 mediates synaptic remodeling via the p75 neurotrophin receptor

Cell surface receptors, ligands, and adhesion molecules underlie development, circuit formation, and synaptic function of the central nervous system and represent important therapeutic targets for many neuropathologies. The functional contributions of interactions between cell surface proteins of neurons and nonneuronal cells have not been fully addressed. Using an unbiased protein-protein interaction screen, we showed that the human immunomodulatory ligand B7-1 (hB7-1) interacts with the p75 neurotrophin receptor (p75NTR) and that the B7-1:p75NTR interaction is a recent evolutionary adaptation present in humans and other primates, but absent in mice, rats, and other lower mammals. The surface of hB7-1 that engages p75NTR overlaps with the hB7-1 surface involved in CTLA-4/CD28 recognition, and these molecules directly compete for binding to p75NTR. Soluble or membrane-bound hB7-1 altered dendritic morphology of cultured hippocampal neurons, with loss of the postsynaptic protein PSD95 in a p75NTR-dependent manner. Abatacept, an FDA-approved therapeutic (CTLA-4-hFc fusion) inhibited these processes. In vivo injection of hB7-1 into the murine subiculum, a hippocampal region affected in Alzheimer's disease, resulted in p75NTR-dependent pruning of dendritic spines. Here, we report the biochemical interaction between B7-1 and p75NTR, describe biological effects on neuronal morphology, and identify a therapeutic opportunity for treatment of neuroinflammatory diseases.

Comparison of Cardiovascular Risk Factors in Obese Blacks and Whites

Blacks are known to have higher blood pressure levels, a higher prevalence of hypertension, and higher body weights than whites. However, the interrelationships of these and other cardiac risk factors have not been analyzed in an obese population. We compared blood pressure (BP) and lipid levels in 174 obese blacks and 939 obese white patients who were entering a weight loss program; we also assessed the effects of weight loss on these factors. Prevalence of treated hypertension was similar in blacks and whites (28% vs. 25%, respectively). In patients not taking BP medication, black women weighed more (108 kg) than white women (102 kg) and black and white males' weights were similar (135 kg vs. 131 kg). Systolic and diastolic BP were similar in black and white women; black males had similar SBP but a significantly lower DBP than white males (83 mmHg vs. 89 mmHg, respectively). Lipid levels were similar in black and white women except black women had lower triglycerides (1.30 mmol/L) than white women (1.58 mmol/L, p < 0.05); and black males compared to white males had significantly lower total cholesterol (4.76 mmol/L vs. 5.56 mmol/L), LDL-cholesterol (3.15 mmol/L vs. 3.52 mmol/L) and triglycerides (1.31 mmol/L vs. 2.17 mmol/L, p < 0.05). Adult-onset obesity adversely affected a number of cardiovascular risk factors in whites, but not in blacks. Blacks lost significantly less weight (-13 kg) than whites (-19 kg). However, controlling for the difference in weight loss, blacks sustained comparable improvement in lipids and blood pressure, except for TC/HDL-C (whites improved significantly more, -0.36 kg/m2, than blacks, 0.03 kg/m2). Thus, the impact of obesity on cardiovascular risk factors seems ameliorated in blacks compared to whites.

Suppression of the bacterial spot pathogen Xanthomonas euvesicatoria on tomato leaves by an attenuated mutant of Xanthomonas perforans

A bacteriocin-producing strain of the bacterial spot of tomato plant pathogen, Xanthomonas perforans, with attenuated pathogenicity was deployed for biocontrol of a bacteriocin-sensitive strain of the genetically closely related bacterial spot of tomato plant pathogen, X. euvesicatoria. The attenuated mutant (91-118DeltaopgHDeltabcnB) of X. perforans was tested in leaf tissue and shown to significantly inhibit internal populations of the wild-type X. euvesicatoria strain although significantly less than the wild-type 91-118 strain, whereas in a phyllosphere inhibition assay, the mutant strain reduced epiphytic populations comparably to 91-118. Thus, the attenuated mutant limited the sensitive bacterium more efficiently on the leaf surface than inside the leaf. In field experiments, weekly application of 91-118DeltaopgHDeltabcnB significantly reduced X. euvesicatoria populations compared to the growers' standard control (copper hydroxide and mancozeb applied weekly and acibenzolar-S-methyl applied every 2 weeks). The biological control agent, 91-118DeltaopgHDeltabcnB, applied every 2 weeks also significantly reduced X. euvesicatoria populations in one season but was not significantly different from the growers' standard control. Potentially, attenuated pathogenic strains could be deployed as biological control agents in order to improve disease control of foliar plant pathogens.

First Report of Tomato spotted wilt virus in Leek (Allium porrum) in the United States

Tomato spotted wilt virus (TSWV) is a member of the family Bunyaviridae. It has many important crop hosts including tomato, pepper, tobacco, peanut, and onion. In Georgia, Vidalia onions (Allium cepa), a close relative of leek, can be infected by TSWV and Iris yellow spot virus (IYSV), which is another thrips-vectored tospovirus (2). For this reason, samples of leek transplants with virus-like symptoms in one field at the border of Georgia and Florida were tested for the presence of TSWV and IYSV. The transplants had been grown from seed in a greenhouse at the same location. The sampled plants exhibited extended bleaching of leaf tips and necrotic lesions. These symptoms were also seen on onion plants infected with TSWV and IYSV. The only natural infections of leek with IYSV have been reported thus far only from Reunion Island (4) and Slovenia (1), but to our knowledge, TSWV has not been reported as a pathogen of leek. Green tissue near the necrotic lesions and bleached tips of one symptomatic leaf per plant was sampled and analyzed using a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) (Agdia, Inc., Elkhart, IN). Of 90 plants tested, eight were positive for TSWV and none were positive for IYSV. Leek samples testing positive using ELISA were blotted onto FTA cards (Whatman Inc., Brentford, UK) to bind viral RNA for preservation and then processed according to the manufacturer's protocol. Punch-outs from the FTA cards were used for reverse transcription polymerase chain reaction (RT-PCR) with the TSWV-specific forward primer (5'-TTAAGCAAGTTCTGTGAG-3') and reverse primer (5'-ATGTCTAAGGTTAAGCTC-3') (3) to confirm the identity of TSWV. The primers are specific to the viral nucleocapsid gene. An amplicon of the expected size (774 bp) was produced from TSWV ELISA-positive leek plants, but not from healthy controls. TSWV has been found in many plants worldwide, but to our knowledge this is the first report of TSWV infecting leek. The effect that TSWV has on leek production is currently unknown. References: (1) D. A. Benson et al. Nucleic Acids Res. 1:32 (Database issue):D23-6, 2004. (2) S. W. Mullis et al. Plant Dis. 88:1285, 2004. (3) H. R. Pappu et al. Tob. Sci. 40:74, 1996. (4) I. Robène-Soustrade et al. Online publication. New Dis. Rep. 11, 2005.

Integrated management of TYLCV/TYLCSV on greenhouse hydroponic tomatoes in Southern Italy

Tomato yellow leaf curl (TYLC) caused by Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl Sardinia virus (TYLCSV), vectored by the whitefly Bemisia tabaci, is a major disease of tomato in Sardinia and Sicily, and is becoming a serious threat in Southern Italy too. TYLCSV was first reported in Calabria region in 1991, but apparently it was an occasional outbreak, and B. tabaci was not detected. Later, during the 2003-2004 winter, a serious epidemic was observed in protected tomato crops in Castrovillari, Cosenza province. TYLCV was first described in Sicily in 2003 and during 2004 in continental Italy. Both viruses were detected in winter 2005-2006 on the Basilicata Ionic coast, in the Metapontum area, both in protected and in open field tomato crops. Experiments were conducted in Calabria Region, Southern Italy, under controlled conditions in a group of greenhouses where several tomato crops were grown hydroponically to determine the separate and integrated effects of UV-reflective mulch (UVRM), Acibenzolar-S-methyl (Actigard) and the two insecticides Imidacloprid (ADMIRE 2F) and Thiamethoxam (ACTARA 25WG). Highly UV-reflective mulch covered plots were treated with Actigard and insecticides, both alone or in combination. TYLC disease incidence was determined from late August 2005 to late January 2006. The highly UVRM alone was effective in reducing disease incidence of about 28.6% at the end of October, and of 31.7% at the end of January. However, Actigard with UVRM significantly reduced TYLC disease incidence to 70% and 48.5%, in 2 months and 5 months after the first treatment, respectively. The insecticides with UVRM, resulted in a moderate reduction of disease incidence (22.5%) at the end of October. At the end of January a reduction in disease incidence due to insecticide applications was not significant. The use of Actigard combined with the insecticides on UVRM reduced the disease incidence (63.4% with Admire and 56.1% with Actara) at the end of January. Actigard alone or with insecticides on UVRM was effective in reducing disease incidences. Highly UVRM and Actigard were effective in reducing the primary spread of TYLCV/TYLCSV in greenhouse hydroponic tomatoes. Comparative analysis of their effects at different periods post-treatment suggests that multiple applications of Actigard may be necessary to reduce progress of this disease.

Application of Acibenzolar-S-Methyl Enhances Host Resistance in Tomato Against Ralstonia solanacearum

The chemical elicitor acibenzolar-S-methyl (ASM; Actigard 50 WG), which induces systemic acquired resistance (SAR), was investigated to determine the effect on bacterial wilt of tomato caused by Ralstonia solanacearum on moderately resistant cultivars under greenhouse and field conditions. In greenhouse experiments, ASM was applied as foliar spray and/or soil drench (3 μg/ml) before and as foliar spray (30 μg/ml) after transplanting. The chemical elicitor was ineffective in reducing bacterial wilt incidence on susceptible tomato cultivars Equinox and FL 47 when plants were inoculated with R. solanacearum. However, greenhouse studies indicated that ASM significantly enhanced resistance in cultivars with moderate resistance to bacterial wilt such as Neptune and BHN 466. It appeared that ASM-mediated resistance was partially due to prevention of internal spread of R. solanacearum toward upper stem tissues of tomato plants. The effect of ASM on moderately resistant cultivars was consistent in field experiments conducted in 2002 and 2003 in Quincy, FL, where bacterial wilt incidence was significantly reduced in ASM-treated BHN 466 (in 2002), FL 7514 (in 2003), and Neptune (both years) plants. ASM-treated BHN 466 and FL 7514 produced significantly higher tomato yield than the untreated controls. This is the first report of ASM-mediated control of bacterial wilt under field conditions, which suggests that use of this treatment for moderately resistant genotypes may be effective for control of bacterial wilt of tomato.

Integration of Biological Control Agents and Systemic Acquired Resistance Inducers Against Bacterial Spot on Tomato

Two strains of plant growth-promoting rhizobacteria, two systemic acquired resistance inducers (harpin and acibenzolar-S-methyl), host-specific unformulated bacteriophages, and two antagonistic bacteria were evaluated for control of tomato bacterial spot incited by Xanthomonas campestris pv. vesicatoria in greenhouse experiments. Untreated plants and plants treated with copper hydroxide were used as controls. The plant growth-promoting rhizobacteria or a tap water control were applied as a drench to the potting mix containing the seedlings, while the other treatments were applied to the foliage using a handheld sprayer. The plant growth-promoting rhizobacteria strains, when applied alone or in combination with other treatments, had no significant effect on bacterial spot intensity. Messenger and the antagonistic bacterial strains, when applied alone, had negligible effects on disease intensity. Unformulated phage or copper bactericide applications were inconsistent in performance under greenhouse conditions against bacterial spot. Although acibenzolar-S-methyl completely prevented occurrence of typical symptoms of the disease, necrotic spots typical of a hypersensitive reaction (HR) were observed on plants treated with acibenzolar-S-methyl alone. Electrolyte leakage and population dynamics experiments confirmed that acibenzolar-S-methyl-treated plants responded to inoculation by eliciting an HR. Application of bacteriophages in combination with acibenzolar-S-methyl suppressed a visible HR and provided excellent disease control. Although we were unable to quantify populations of the bacterium on the leaf surface, indirectly we determined that bacteriophages specific to the target bacterium reduced populations of a tomato race 3 strain of the pathogen on the leaf surface of acibenzolar-S-methyl-treated plants to levels that did not induce a visible HR. Integrated use of acibenzolar-S-methyl and phages may complement each other as an alternative management strategy against bacterial spot on tomato.

Evaluation of Thymol as Biofumigant for Control of Bacterial Wilt of Tomato Under Field Conditions

Volatile plant essential oils thymol and palmarosa oil, used at a concentration of 0.7%, were evaluated under field conditions for control of bacterial wilt of tomato caused by Ralstonia solanacearum. The experimental fields were artificially infested with the bacterial pathogen. Two hours after infestation, the plant essential oils were applied, then the plots were sealed with plastic mulch for 3 or 6 days. Tomato seedlings were transplanted into the field 7 days later. In fall of 2002, 92.5% of tomato plants (cv. Equinox) wilted in the untreated control plots. Both thymol and palmarosa oil soil treatments reduced bacterial wilt incidence significantly. Thymol was more effective than palmarosa oil based on the final assessment, when 33.1 and 48.1% of the plants had wilted in plots treated with thymol and palmarosa oil, respectively. Soil treatment with either thymol or palmarosa oil produced significantly higher yield of tomato than the untreated control. In 2003, only thymol was evaluated. Thymol application significantly reduced bacterial wilt incidence on the susceptible cultivar Solar Set. Disease incidence in untreated plots reached 65.5%, while in thymol treated plots only 12% of plants wilted. Thymol treatment also increased yield of Solar Set significantly compared with the untreated control. This is the first report on the use of thymol for controlling a plant disease under field conditions, which indicated that this compound provided effective control of bacterial wilt on susceptible tomato cultivars when used as preplant treatment of soils. Because of its volatile property and broad-spectrum functions, thymol shows potential to be used as a soil biofumigant for the management of various plant pathogens.

Integrated Management of Tomato Spotted Wilt on Field-Grown Tomatoes

Epidemics of spotted wilt caused by Tomato spotted wilt virus (TSWV) vectored by Frankliniella occidentalis and possibly other thrips species occur regularly in tomato in the southeastern United States. Field experiments were conducted to determine the effects of UV-reflective mulch, acibenzolar-S-methyl (plant activator), and insecticides on progress of tomato spotted wilt incidence and population dynamics of flower thrips (including F. occidentalis, F. tritici, and F. bispinosa). Whole plots of tomatoes grown on UV-reflective and black polyethylene mulch were divided into subplots of acibenzolar-S-methyl and no acibenzolar-S-methyl, and sub-subplots of insecticide and no insecticide for thrips control. The UV-reflective mulch was more effective than black polyethylene mulch each year in reducing colonization of thrips in May and the consequent primary infections of tomato spotted wilt. Application of acibenzolar-S-methyl further reduced tomato spotted wilt incidence in 2000 and 2002, when disease pressure was great. Reproduction of thrips on tomato was poor in these experiments, but their control in the insecticide-treated sub-subplots prevented secondary spread in both years. The combination of UV-reflective mulch, acibenzolar-S-methyl, and insecticides was very effective in reducing tomato spotted wilt incidence in tomato.

Management of Tomato Bacterial Spot in the Field by Foliar Applications of Bacteriophages and SAR Inducers

Various combinations of the harpin protein, acibenzolar-S-methyl, and bacteriophages were compared for controlling tomato bacterial spot in field experiments. Harpin protein and aciben-zolar-S-methyl were applied every 14 days beginning twice before transplanting and then an additional four applications throughout the season. Formulated bacteriophages were applied prior to inoculation followed by twice a week at dusk. A standard bactericide treatment, consisting of copper hydroxide plus mancozeb, was applied once prior to inoculation and then every 7 days, while untreated plants served as an untreated control. Experiments were conducted in north and central Florida fields during fall 2001, spring 2002, and fall 2002. In three consecutive seasons, acibenzolar-S-methyl applied in combination with bacteriophage or bacteriophage and harpin significantly reduced bacterial spot compared with the other treatments. However, it did not significantly affect the total yield compared with the standard or untreated control. Application of host-specific bacteriophages was effective against the bacterial spot pathogen in all three experiments, providing better disease control than copper-mancozeb or untreated control. When results of the disease severity assessments or harvested yield from the bacteriophage-treated plots were grouped and compared with the results of the corresponding nonbacteriophage group, the former provided significantly better disease control and yield of total marketable fruit.

Efficacy of Plant Growth-Promoting Rhizobacteria, Acibenzolar-S-Methyl, and Soil Amendment for Integrated Management of Bacterial Wilt on Tomato

Greenhouse experiments were conducted to study the effect of plant growth promoting rhizobacteria (PGPR; Bacillus pumilus SE 34, Pseudomonas putida 89B61, BioYield, and Equity), acibenzolar-S-methyl (Actigard), and a soil amendment with S-H mixture (contains agricultural and industrial wastes such as bagasse, rice husk, oyster shell powder, urea, potassium nitrate, calcium super phosphate, and mineral ash) on bacterial wilt incidence caused by Ralstonia solanacearum (race 1, biovar 1) in susceptible tomato (Lycopersicon esculentum cv. Solar Set). In experiments with PGPR, Pseudomonas putida 89B61 significantly reduced bacterial wilt incidence when applied to the transplants at the time of seeding and 1 week prior to inoculation with Ralstonia solanacearum. BioYield, a formulated PGPR that contained two Bacillus strains, decreased disease significantly in three experiments. Equity, a formulation containing more than 40 different microbial strains, did not reduced wilt incidence compared with the untreated control. With inoculum at low pathogen densities of 1 × 10⁵ and 1 × 10⁶ CFU/ml, disease incidence of Actigard-treated plants was significantly less than with nontreated plants. This is the first report of Actigard-mediated reduction of bacterial wilt incidence in a susceptible tomato cultivar. When PGPR and Actigard applications were combined, Actigard plus P. putida 89B61 or BioYield reduced bacterial wilt incidence compared with the untreated control. Incorporation of S-H mixture into infested soil 2 weeks before transplanting reduced bacterial wilt incidence in one experiment. Combination of Actigard with the S-H mixture significantly reduced bacterial wilt incidence in tomato in two experiments.

Improved Efficacy of Newly Formulated Bacteriophages for Management of Bacterial Spot on Tomato

Bacteriophages are currently used as an alternative method for controlling bacterial spot disease on tomato incited by Xanthomonas campestris pv. vesicatoria. However, the efficacy of phage is greatly reduced due to its short residual activity on plant foliage. Three formulations that significantly increased phage longevity on the plant surface were tested in field and greenhouse trials: (i) PCF, 0.5% pregelatinized corn flour (PCF) + 0.5% sucrose; (ii) Casecrete, 0.5% Casecrete NH-400 + 0.5% sucrose + 0.25% PCF; and (iii) skim milk, 0.75% powdered skim milk + 0.5% sucrose. In greenhouse experiments, the nonformulated, PCF-, Casecrete-, and skim milk-formulated phage mixtures reduced disease severity on plants compared with the control by 1, 30, 51, and 62%, respectively. In three consecutive field trials, nonformulated phage caused 15, 20, and 9% reduction in disease on treated plants compared with untreated control plants, whereas plants treated with PCF- and Casecrete-formulated phage had 27, 32, and 12% and 30, 43, and 24% disease reduction, respectively. Plants receiving copper-mancozeb treatments were included in two field trials and had a 20% decrease in disease in the first trial and a 13% increase in the second one. Skim milk-formulated phage was tested only once and caused an 18% disease reduction. PCF-formulated phage was more effective when applied in the evening than in the morning, reducing disease on plants by 27 and 13%, respectively. The Casecrete-formulated phage populations were over 1,000-fold higher than the nonformulated phage populations 36 h after phage application.

Effects of Plant Essential Oils on Ralstonia solanacearum Population Density and Bacterial Wilt Incidence in Tomato

Greenhouse experiments were conducted to determine the effectiveness of plant essential oils as soil fumigants to manage bacterial wilt (caused by Ralstonia solanacearum) in tomato. Potting mixture ("soil") infested with R. solanacearum was treated with the essential oils at 400 mg or μl and 700 mg or μl per liter of soil in greenhouse experiments. R. solanacearum population densities were determined just before and 7 days after treatment. Populations declined to undetectable levels in thymol, palmarosa oil, and lemongrass oil treatments at both concentrations, whereas tea tree oil had no effect. Tomato seedlings transplanted in soil treated with 700 mg/liter of thymol, 700 ml/liter of palmarosa oil, and 700 ml/liter of lemongrass oil were free from bacterial wilt and 100% of plants in thymol treatments were free of R. solanacearum. Soil amendment with fresh leaves of essential oil-producing plants did not reduce bacterial wilt incidence compare to untreated inoculated control. Some thyme oil-producing plants such as thyme (Thymus vulgaris) cv. German winter, Creeping thyme (Thymus serpyllum), and Greek oregano (Origanum vulgare subsp. hirtum), while remaining symptomless, became systemically infected by R. solanacearum and were therefore identified as hosts of R. solanacearum.

An invasive cleavage assay for direct quantitation of specific RNAs

RNA quantitation is becoming increasingly important in basic, pharmaceutical, and clinical research. For example, quantitation of viral RNAs can predict disease progression and therapeutic efficacy. Likewise, gene expression analysis of diseased versus normal, or untreated versus treated, tissue can identify relevant biological responses or assess the effects of pharmacological agents. As the focus of the Human Genome Project moves toward gene expression analysis, the field will require a flexible RNA analysis technology that can quantitatively monitor multiple forms of alternatively transcribed and/or processed RNAs (refs 3,4). We have applied the principles of invasive cleavage and engineered an improved 5'-nuclease to develop an isothermal, fluorescence resonance energy transfer (FRET)-based signal amplification method for detecting RNA in both total RNA and cell lysate samples. This detection format, termed the RNA invasive cleavage assay, obviates the need for target amplification or additional enzymatic signal enhancement. In this report, we describe the assay and present data demonstrating its capabilities for sensitive (<100 copies per reaction), specific (discrimination of 95% homologous sequences, 1 in > or =20,000), and quantitative (1.2-fold changes in RNA levels) detection of unamplified RNA in both single- and biplex-reaction formats.

First Report of Tomato spotted wilt virus in Habanero and Tabasco Peppers in Florida

In spring 2000, symptoms similar to thrips-vectored spotted wilt disease caused by Tomato spotted wilt virus (TSWV) were observed on habanero (Capsicum chinense) and tabasco (Capsicum frutescens) peppers in north Florida. Habanero peppers were from commercial fields grown for specialty markets and tabasco peppers were from research plots. Symptoms observed were leaf necrosis, fruit drop, necrotic stem lesions, and stunting. Fruit symptoms included chlorotic and necrotic spotting and distinct ring pattern and distortion. The incidence of symptomatic habanero peppers was 7 to 8% in one of the three production fields visited, and a lower incidence in two other fields (all in Jackson County). In tabasco pepper, TSWV was detected in spring and fall 1999, and spring 2000 seasons in 10 to 15% of the plants (Gadsden County). Adjacent tomato fields contained scattered plants exhibiting symptoms of TSWV. Diagnosis of TSWV from symptomatic stems, leaves, and fruit of habanero and tabasco peppers was confirmed by a double antibody sandwich enzyme linked immunosorbent assay (ELISA) using a commercially available kit (Agdia Inc., Elkhart, IN). ELISA values ranged from 1.57 to 1.95 for habanero pepper and 0.80 to 0.95 for tabasco pepper. The mean ELISA value of the negative controls was 0.001. To further verify TSWV infection, immunocapture reverse transcription-polymerase chain reaction (IC-RT-PCR) was performed (1). The primer pair 5'-ATGTCTAAGGTTAAGCTC-3' and 5'-TTAAGCAAGTTCTGTGAG-3' represented the first and last 18 bases of the coding region of the nucleocapsid gene of TSWV, respectively, and produces approximately 800 bp PCR product (1). IC-RT-PCR gave a single DNA band of expected size in both habanero and tabasco samples, while no amplification was found in an uninfected pepper sample. This is the first report of TSWV on habanero and tabasco peppers in Florida. TSWV continues to be an economically important disease constraint to the production of tomato, pepper (C. annuum), peanut, and tobacco in the southeastern United States (observations from Georgia and Florida). Meanwhile, the known host range is expanding to include new species of cultivated vegetables. References: (1) R. K. Jain et al.. Plant Dis. 82:900, 1998.

Utility of Mi Gene Resistance in Tomato to Manage Meloidogyne javanica in North Florida

Three field trials were conducted to determine response of Meloidogyne javanica to tomato cultivars containing the Mi gene for resistance in sequential tests. Trials were conducted in spring and fall 1997 and spring 1998 on the same site. Tomatoes were grown on polyethylene mulch at a site initially treated with methyl bromide and then infested with M. javanica via drip tubing. Cultivars with the Mi gene were 'PSR 8991994' and 'Sanibel', and susceptible cultivars were 'Colonial' and 'Agriset 761'. The resistant cultivars greatly suppressed root galling in the three tests. Population densities of second-stage juveniles also were low in soil samples collected from resistant cultivars. Tomato fruit yields were significantly increased in only one test when using resistant cultivars. However, the susceptible cultivars are high-yielding and recommended for north Florida production, while the cultivars containing the Mi gene are not as well adapted. In the three successive crops, no evidence of resistance-breaking biotypes of M. javanica was observed. With further incorporation into adapted cultivars, the Mi gene resistance could be a valuable tool to manage M. javanica in north Florida stake tomato production.

First Report of Tomato Yellow Leaf Curl Virus in Tomato in South Georgia

In October 1998, symptoms characteristic of tomato yellow leaf curl virus (TYLCV) were observed on fresh market tomato (Lycopersicon esculentum Mill.) in four production fields, two in Decatur County, Georgia, and two in Gadsden County, Florida. Symptoms observed were plant stunting, reduced leaf size, yellow leaf margins, and mottling. The incidence of symptomatic plants was less than 1% in all fields examined. In most cases, symptoms were observed only on the upper portion of plants, suggesting these plants had been infected by secondary spread from an unknown source. Nuclear inclusions characteristic of geminiviruses were observed by light microscopy in leaf tissue from symptomatic plants (1). To identify the geminivirus, total DNA from infected plants was extracted from six symptomatic tomato plants (two from Georgia and four from Florida) for polymerase chain reaction (PCR; J. E. Polston, personal communication). DNA was amplified with geminivirus DNA A degenerate primer set PAL1v1978 and PAR1c496 (2) from these extracts in addition to extracts from a known TYLCV-infected, a tomato mottle virus (ToMoV)-infected, and a healthy tomato plant. A PCR product of 1.4 kb was obtained from plants with TYLCV-like symptoms, while a 1.4-kb product and a 1.1-kb product were obtained from extracts of the known TYLCV-infected and ToMoV-infected tomato plants, respectively. No PCR product was obtained from extracts of healthy tomato plants. The 1.4-kb PCR products from one Georgia sample and one Florida sample were compared with those of TYLCV and ToMoV by restriction enzyme (RE) digestion with EcoRI and ClaI. The RE pattern of the 1.4-kb fragment from both samples was identical to the RE pattern of TYLCV and different from that of ToMoV. Adult and immature whiteflies collected from the fields where TYLCV was found were identified as Bemisia tabaci, the vector of TYLCV, but the biotype was not established. This report of TYLCV in south Georgia and north Florida extends the geographic range of TYLCV in the U.S. northward approximately 100 km. Georgia is the second state in which TYLCV was found since its initial detection in south Florida in July 1997 (J. E. Polston, personal communication). Monitoring of silverleaf whitefly populations and detection of TYLCV on alternate hosts will continue in order to estimate the potential impact of this virus on south Georgia and north Florida agriculture. References: (1) R. G. Christie and J. R. Edwardson. Plant Dis. 70:273, 1986, (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.

Evaluation of a community-based program to improve infant immunization rates in rural Minnesota

OBJECTIVE

The purpose of this study was to evaluate the effects of enrollment in a community-based public health nursing program, Communities Caring for Children (CCC), on infant immunization rates in rural Minnesota. The program involved health education, a registry, and a reminder system.

DESIGN

The evaluation was a collaborative effort of university, public health agency, and private managed-care personnel. Two data sources were used to assess the association of program enrollment and immunization compliance; public birth certificates and a telephone survey of 421 CCC enrollees and non-enrollees.

RESULTS

Birth certificate and survey data showed that CCC enrollees were significantly younger, less educated, more likely to be white, and of lower parity than non-enrollees. The average age of subjects' infants was eight months. The survey data showed that, overall, CCC enrollees perceived less danger in infant immunizations than did non-enrollees and were more likely than non-enrollees to have access to infant immunization reminder cards. CCC enrollees reported significantly higher immunization compliance for their infants than did non-enrollees.

CONCLUSIONS

The area served by this program is relatively low-income and rural. Infant immunization status was among the lowest in Minnesota prior to the implementation of CCC. The evaluation suggested that enrollment in CCC was one of the most powerful predictors of infant immunization compliance.

Adaptation of soil solarization to the integrated management of soilborne pests of tomato under humid conditions

ABSTRACT Soil solarization was shown to be cost effective, compatible with other pest management tactics, readily integrated into standard production systems, and a valid alternative to preplant fumigation with methyl bromide under the tested conditions. Solarization using clear, photoselective, or gas-impermeable plastic was evaluated in combination with metham sodium, 1,3-dichloropropene + chloropicrin, methyl bromide + chloropicrin, pebulate, or cabbage residue. Strip solarization, applied to 20-cm-high, 0.9-m-wide beds, was conducted to achieve compatibility with standard production practices and resulted in soil temperatures 2 to 4 degrees C above those temperatures resulting when using conventional flatbed solarization. Soil temperatures were 1 to 2 degrees C higher at the edges of the raised beds, eliminating any border effects associated with solarization. Following a 40- to 55-day solarization period, the plastic was painted white and used as a production mulch for a subsequent tomato crop. The incidence of Southern blight and the density of Paratrichodorus minor and Criconemella spp. were lower (P < 0.05) in solarized plots. No differences (P < 0.05) in the incidence of Fusarium wilt and the density of nutsedge and Helicotylenchus spp. were observed between plots receiving solarization and plots fumigated with a mixture of methyl bromide + chloropicrin. The severity of root galling was lower (P < 0.05) when soil solarization was combined with 1,3-dichloropropene + chloropicrin (16.2 + 3.4 g/m(2)) and a gas-impermeable film. The incidence of bacterial wilt was not affected by soil treatments. Marketable yields in plots using various combinations of soil solarization and other tactics were similar (P < 0.05) to yields obtained in plots fumigated with methyl bromide + chloropicrin. The results were validated in several large scale field experiments conducted by commercial growers.

Abdominal stab wound protocol: prospective study documents applicability for widespread use

Traditionally, stab wounds violating the abdominal wall fascia led to exploratory celiotomy that was often nontherapeutic. In an attempt to limit the number of nontherapeutic celiotomies (NTC), we devised a protocol to prospectively study stab wounds violating the anterior abdominal wall fascia. Through protocol, abdominal stab wounds were explored in stable adults. If the anterior fascia was violated, paracentesis and, if necessary, peritoneal lavage was undertaken in the absence of previous abdominal surgery. If evisceration was noted, it was reduced and the patient lavaged. Fascial penetration was noted in 72 patients. 46 patients underwent celiotomy: because of shock/peritonitis in 8 (2 NTC), fascial penetration with a history of previous celiotomy in 7 (5 NTC), positive paracentesis in 20 (5 NTC), or positive lavage in 10 (4 NTC). One patient underwent late celiotomy without ill-effect after a negative lavage because she subsequently developed fever and localized peritonitis (ice pick injury to cecum). Eleven patients had evisceration; nine underwent celiotomy. Patients with abdominal stab wounds can be selectively managed safely. More than one-third with fascial penetration, some with evisceration, avoided exploration. Only one patient underwent delayed celiotomy and did so without detriment. Nontherapeutic celiotomy rates were highest in patients with previous abdominal surgery who, thereby, could not undergo paracentesis/lavage; excluding these patients, the nontherapeutic celiotomy rate was 17% (11/65) for those with fascial penetration.

Reduction of phytoparasitic nematodes on tomato by soil solarization and genotype

The effects of soil solarization and tomato (Lycopersicon esculentum) genotype on populations of plant-parasitic nematodes and bacterial wilt were examined in North Florida. Maximum soil temperatures achieved under solarization treatments using a photoselective polyethylene mulch were 49.5, 46, and 40.5 C at depths of 5, 15, and 25 cm, respectively. Soil solarization reduced (P < 0.05) populations of Paratrichodorus minor, Rotylenchulus reniformis, and Criconemella spp. 85 days after transplanting on the cultivar Solar Set. Soil solarization reduced (P < 0.10) populations of P. minor, R. reniformis, and Criconemella spp. on the breeding line Fla. 7421. Reductions of P. minor and Criconemella spp. on Solar Set and Fla. 7421 were similar to those achieved by fumigation with a 67:33 mixture of methyl bromide and chloropicrin (448 kg/ha). Fla. 7421 reduced (P < 0.10) populations of R. reniformis compared with Solar Set. Neither soil solarization nor fumigation reduced the incidence of bacterial wilt on the susceptible cultivar Solar Set. This study demonstrates the ability of soil solarization to provide season-long control of plant-parasitic nematodes of tomato under a climatic regime characterized by periods of abundant rainfall and extended cloud cover.

Prehospital traumatic cardiac arrest: the cost of futility

Of 12,462 trauma patients cared for by prehospital services from October 1, 1989 to March 31, 1991, 138 patients underwent CPR at the scene or during transport because of the absence of blood pressure, pulse, and respiration. Ninety-six (70%) suffered blunt trauma, 42 (30%) suffered penetrating trauma. Sixty (43%) were transported by air utilizing county-wide transport protocols. None of the patients survived. Aggregate care cost $871,186.00. In 11 cases (8%), tissue for transplantation was procured (only corneas).

CONCLUSION

Trauma patients who require CPR at the scene or in transport die. Infrequent organ procurement does not seem to justify the cost (primarily borne by hospitals), consumption of resources, and exposure of health care providers to occupational health hazards. The wisdom of transporting trauma victims suffering cardiopulmonary arrest at the scene or during transport must be questioned. Allocation of resources to these patients is not an insular medical issue, but a broad concern for our society, and society should decide if the "cost of futility" is excessive.

Long-term follow-up of patients attending a combination very-low calorie diet and behaviour therapy weight loss programme

We examined the effects of treatment with a very-low calorie diet (VLCD) combined with behaviour modification on weight loss and long-term maintenance of weight loss in 118 of 199 patients who completed eight weeks of VLCD. Those who began therapy in 1984 were surveyed by telephone an average of 3.3 years after ending the VLCD. Questionnaire data included reported weight, exercise, eating, work and sleep habits, emotional factors, and current use of behavioural techniques taught in the programme. Results showed that mean maximum weight loss during the time they attended the programme (average 51.6 weeks) was 31.3 kg, corresponding to a decrease in body mass index of 10.7 kg/m2. At follow-up a regain of 60.9% was reported yielding a net overall weight loss of 13.6 kg and decrease in body mass index of 4.4 kg/m2. Seventy-five per cent of subjects showed only a 37.5% regain of the weight they had lost. Those whose weight loss was better maintained at the time of follow-up reported exercising more, eating fewer high fat foods, and using more of the behavioural techniques taught in the programme. This study provides support for the conclusion that some patients treated with VLCD and behaviour modification can maintain significant weight losses over a relatively long period of time and that specific behaviours relate to this success.

The equilibrium position of the mitral valve: an accurate model of mitral valve motion in humans

A "semiopen" diastolic equilibrium position of the mitral valve that is assumed in the absence of transmitral flow has been demonstrated in instrumented dogs. It has been suggested that the papillary muscles and chordae tendineae play an integral role in returning the valve to this position after initial diastolic opening. To determine whether such a model of mitral valve motion is valid in noninstrumented humans without underlying valvular disease, M-mode and Doppler ultrasound studies were performed in 6 subjects who underwent prolonged periods of ventricular diastole and atrial inactivity. After maximal opening, the mitral valve assumed a stable open position in which mean separation of the anterior and posterior mitral leaflets was 52% of maximal separation. This position was maintained for a mean duration of 585 ms, during which time transmitral flow fell to 0 m/s. Peak mitral valve opening preceded the early transmitral flow peak by an average of 42 ms, suggesting an active closure of the mitral valve as flow continued to accelerate. It is concluded that a semiopen equilibrium position of the mitral valve is assumed during prolonged diastolic periods in the absence of transmitral flow and is an accurate model describing diastolic mitral valve motion in noninstrumented humans. The chordae tendineae and papillary muscles may actively participate in the genesis and maintenance of the equilibrium position.

Effect of acute standing and prolonged upright activity on left ventricular hemodynamics, systolic and diastolic intervals, and QT-QS2 relationship

It is generally accepted that upright posture decreases preload and afterload, which could alter left ventricular (LV) performance. It is not known if changes occurring with acute standing persist after prolonged ambulatory activity (amb-act). In seven normal subjects echocardiographic end-diastolic and end-systolic diameters, percent shortening of the internal diameter (% delta D) and end-systolic wall stress (ES-WS), radionuclide diastolic volume and ejection fraction, preejection period over left ventricular ejection time (PEP/LVET), and diastolic time and QT-QS2 were measured supine, within 1 to 2 minutes after standing and after prolonged (60 minutes) amb-act. In addition, serial measurements were performed in PEP/LVET for 105 minutes at 15-minute intervals. With acute standing, end-diastolic diameter, diastolic volume, and ES-WS decreased (p less than 0.01); heart rate and PEP/LVET increased (p less than 0.01); while % delta D and ejection fraction remained unchanged. There was an inverse correlation between change in PEP/LVET and diastolic diameter (r = -0.59), but no correlation between PEP/LVET and ES-WS. The diastolic time per beat and per minute decreased (375 +/- 115 msec from 519 +/- 176 msec [p less than 0.01] and 31.3 +/- 4.2 sec/min from 33.7 +/- 4.5 sec/min [p less than 0.01]). The QT-QS2 increased when compared to supine (-7 +/- 7.6 msec from -22 +/- 7.7 msec [p less than 0.005]), but the QT-QS2 relationship remained normal (QT less than or equal to QS2). All the dynamic changes that occurred with acute standing tended to persist during prolonged amb-act.

Feasibility of prime vendor purchasing for a state university hospital

The economic feasibility of implementing a prime vendor purchasing system for pharmaceuticals was evaluated in a midwestern university hospital. Inventory costs, personnel costs, and check processing costs under the current purchasing system were compared with costs estimated for a proposed prime vendor purchasing system. For each step in the purchasing process that would be changed under the proposed system, work measurement techniques were used to determine personnel costs. The total savings from reductions in inventory holding costs, personnel costs, and check processing costs under the proposed prime vendor system was +98,396.37, or 2.4% of the value of pharmaceuticals purchased. Since the pharmacy department could not negotiate a contract in which the prime vendor's service fee was 2.4% or less, implementing a prime vendor purchasing system would not have been cost effective. Therefore, the hospital retained its existing purchasing system. Through detailed analysis of the major costs involved in pharmaceutical purchasing, the hospital was able to determine that it was not cost effective for it to use prime vendor purchasing.