Methodology for Inoculating Sweetpotato Virus Disease: Discovery of Tip Dieback, and Plant Recovery and Reversion in Different Clones.

Evaluating sweetpotato (Ipomoea batatas) genotypes for resistance to sweetpotato virus disease (SPVD) has been slow and inefficient. Ipomoea setosa plants, normally used as the source of scions for graft-infecting sweetpotatoes with viral diseases, are often severely stunted and their mortality is 10 to 30% when infected with SPVD, making them unsuitable as scions. Tanzania, a landrace of I. batatas widely grown in East Africa, was found to be a superior host for maintaining and increasing SPVD inoculum (scions) for mass grafting. Modifications to a cleft-grafting technique also increased survival of grafted SPVD-affected scions from 5 to 100%. These modifications, coupled with an efficient SPVD scoring technique, allowed rapid screening of large sweetpotato populations for SPVD resistance. Plant recovery from SPVD is reported here as a component of SPVD resistance. Differences in recovery from SPVD were detected among progenies, indicating its genetic basis. Plant tip dieback, a hypersensitivity response, was observed only in families with cv. Wagabolige as a parent. These findings may open up new opportunities for improved understanding and control of this devastating disease.

Host Range, Purification, and Genetic Variability in Sweet potato chlorotic fleck virus.

Sweet potato chlorotic fleck virus (SPCFV) has recently been classified as a putative new member of the genus Carlavirus (family Flexiviridae) on the basis of its molecular properties. In this study, SPCFV was characterized in terms of host range, physical and biological characteristics, and genetic variability. In addition to sweet potato, SPCFV infected some plant species in the families Convolvulaceae, Chenopodiaceae, and Solanaceae. Limited numbers of virus particles were observed in the assimilation parenchyma cells of infected plant tissues; some cells had a distorted and enlarged endoplasmic reticulum though without any cytoplasmic and amorphous inclusions. The normal length of SPCFV particles was determined to be approximately 800 nm. In enzyme-linked immunosorbent assays, polyclonal antibodies raised against purified SPCFV virions were able to detect the virus in infected sweet potato and indicator plant tissues. In immunoelectron microscopy, SPCFV particles were all strongly decorated when reacted with homologous antiserum. Comparison of the 3' terminal part of the genome of a range of geographically diverse isolates revealed a high level of genetic diversity. The amino acid sequence identity in the coat protein and the nucleic acid binding protein ranged from 89 to 99.7% and from 75.9 to 99.2%, respectively. Phylogenetic analysis of both proteins showed a geographically associated clustering into two genogroups.

Private psychiatric hospitals: "excellence is their watchword".

Throughout their history private psychiatric hospitals have been a major force in psychiatry, and their humanistic concern for the mentally ill has resulted in numerous innovations in treatment. Over the past two decades the sharp increase in psychiatric patient care episodes has resulted in a greater reliance on private psychiatric hospitals, and they have reponded by modifying their role, broadening the spectrum of patients served, and developing alternatives to inpatient treatment. In addition to continuing to provide high-quality inpatient care, private psychiatric hospitals in the future should expand various alternatives to such care, explore opportunities for collaboration with other health care systems, and provide more patient services to the underserved.

First-pass radionuclide angiography using a multiwire gamma camera and tantalum-178.

A portable multiwire gamma camera (MWGC) with enhanced imaging characteristics relative to conventional sodium iodide camera has been evaluated with 178Ta, a short-lived, generator-produced radioisotope (half-life 9.3 min). First-pass radionuclide angiography (FPRA) was performed and results were compared to those obtained with FPRA using a multicrystal camera (MCC) and 99mTc in 38 patients. The overall left ventricular count sensitivity (counts/mCi/sec/millisteradians [msr]) was significantly higher with MWGC/178Ta (176 +/- 132 versus 108 +/- 49, p less than 0.001) yielding images of higher statistics with higher resolution collimation (31 versus 63 msr). Left ventricular ejection fraction was 0.54 +/- 0.18 by MWGC and 0.54 +/- 0.18 by MCC with an excellent correlation between the two techniques (r = 0.94, s.e.e. = 0.06). The detection of wall motion abnormality was virtually identical with the two techniques. Intra- and interobserver reproducibility by MWGC was excellent (r = 0.99 and 0.99, respectively). Thus, this new technology provides first-pass studies of higher statistical quality and improved resolution, affording more precise assessment of left ventricular performance and likelihood of further substantial improvement by use of even higher doses of 178Ta.

RNA extraction from virus-diseased sweet potato for reverse transcriptase polymerase chain reaction analysis.

Sweet potato virus disease (SPVD), which causes severe crop losses in Africa, is caused by a complex of sweet potato feathery mottle potyvirus (SPFMV) and sweet potato chlorotic stunt crinivirus (SPCSV). Extraction of pure RNA (for diagnosis by reverse transcriptase polymerase chain reaction [RT-PCR] methods) from diseased sweet potato proved to be difficult using five different total-RNA extraction procedures: (a) that of Chomczynski and Sacchi (1) (b) an adaptation of Lodhi et al., (2) and three commercially available kits (c) Clonsep (Clontech, Clontech Labs Inc, Palo Alto, CA; (d) RNeasy (Qiagen, West Sussex, UK); and (e) RNA isolator (Genosys Biotechnologies). Four of these methods (b-e) generated sufficient RNA, but it was unsuitable for RT-PCR amplification of SPFMV. When these RNA samples were treated with Wizard DNA extraction resin (Promega), the inhibitors of RT-PCR were consistently removed from three (b-d) of these four samples. Another deproteinating step was needed to allow RT-PCR amplification of sample e. The Wizard DNA column purification in conjunction with one of these total RNA extraction methods facilitates quick and reliable extraction of pure RNA for diagnostic purposes and might be suitable for similar problematic plant material.

Two Serotypes of Sweetpotato feathery mottle virus in Uganda and Their Interaction with Resistant Sweetpotato Cultivars.

ABSTRACT Isolates of Sweetpotato feathery mottle virus (SPFMV, genus Potyvirus, family Potyviridae) were obtained in several districts of Uganda from sweetpotato plants infected with the sweetpotato virus disease (SPVD), the most important disease of this crop in Africa. A monoclonal antibody (MAb 7H8) raised against the coat proteins (CP) of a mixture of the SPFMV strain C (United States) and the isolate SPV-I (West Africa) distinguished Ugandan SPFMV isolates into those detectable and not detectable by the MAb. These two serotypes differed in prevalence in different districts of Uganda and in two common sweetpotato cultivars. Both serotypes could be transmitted simultaneously by single aphids. The serotypes differed in their ability to systemically coinfect sweetpotatoes that were infected with Sweetpotato chlorotic stunt virus (SPCSV, genus Crinivirus), the virus required to induce SPVD in SPFMV-infected plants. One sweetpotato breeding line, resistant to SPFMV from the New World, was infected by graft-inoculation with all SPFMV isolates from Uganda. Another SPFMV-resistant sweetpotato line became infected with SPFMV and developed SPVD only following coinoculation with SPCSV.

An epidemiological study of roadway fatalities related to farm vehicles: United States, 1988 to 1993.

Compared with the estimated injury fatality rate for workers in all occupations (nine in 100,000 in 1988) the farm fatality rate (48 in 100,000) was among the highest in the nation; in 1993, these rates were eight and 35 in 100,000, respectively. On-road farm-vehicle fatalities have been identified as a significant problem, yet these events apparently have not been investigated in a comprehensive manner. The purpose of this study was to investigate the circumstances surrounding all on-road, non-truck, farm-vehicle crash fatalities in the United States form 1988 through 1993. The National Highway Traffic Safety Administration's Fatal Accident Reporting System, which includes data for all US fatal on-road motor vehicle crashes, was the source of data. Driver-related variables were compared among farm vehicles, vehicles in collisions with farm vehicles, and all other vehicles in rural, fatal crashes; environmental variables were compared between rural farm-vehicle and non-farm-vehicle crashes. During 1988 to 1993, in rural areas, 444 farm-vehicle occupants were killed; in addition, 238 occupants of other vehicles or pedestrians were killed in collisions with the farm vehicles. The farm vehicles were disproportionately involved in overturns, rear-end collisions, and incidents in which the injured person fell from the vehicle, when compared with all other non-farm vehicles involved in rural-area fatal crashes. Of the farm vehicles involved in fatal crashes at night, dawn, or dusk, 65% were struck in the rear, compared with 4% of vehicles involved in fatal non-farm-vehicle crashes. Compared with drivers in all other rural crashes, farm-vehicle operators were more likely to be male, have a greater proportion of convictions for driving while intoxicated, and a lower proportion of previous speeding convictions. From this initial investigation, it appears that the fatal-crash involvement of farm vehicles are related to vehicle and environmental factors that are changeable. Given the proportion of overturns associated with farm-vehicle crashes (21%) compared with non-farm vehicles (9%), there is a need to investigate design characteristics of the farm vehicles. The large proportion of farm vehicles struck in the rear during daylight (24%) as well as night, dawn, or dusk hours (65%), compared with non-farm vehicles (4% and 4%, respectively), suggest factors related to visibility and perception of the farm vehicles' speed that provide a basis for further study.

A population-based study of tractor-related injuries: Regional Rural Injury Study-I (RRIS-I).

Although tractors account for the majority of fatal farming-related injuries, little is known about the magnitude of this problem. The study population in this article was obtained from the five state Regional Rural Injury Study-I (RRIS-I) database that included 3939 farm households and 13,144 persons interviewed during 1990. Rates were calculated for sociodemographic variables and various exposures; logistic regression was used to calculate the relative risks and respective confidence intervals. Among the total farming-related injury events (n = 764), 65 (8.4%) were related to regular tractor (> or = 20 horsepower) use (495 injured persons per 100,000 persons per year). The rates increased incrementally for those persons working between 20 to 39 and 60 to 79 hours per week (range, 529 to 1430 per 100,000 persons). Among the 12 rollover events, there were only three injuries. The majority of injury events occurred while persons were mounting or dismounting the tractor (42%). Although only 7% of the cases were hospitalized, 83% required some type of health care. Among all injured persons, 43% were restricted from regular activities for 1 week or more and 20% were restricted for 1 month or more; 28% continued to have persistent problems. The finding of the large proportion of events associated with activities of mounting and dismounting suggests a need to investigate specific design characteristics of the tractors associated with these events and, in general, the tractors to which the population is exposed.

Machinery-related injuries: regional rural injury study--I (RRIS--I).

Although it is known that farm machinery is a source of serious and catastrophic farm work-related injuries, little is known about the magnitude of, and potential risk factors for, this problem. The study population is from the five-state Regional Rural Injury Study--I (RRIS--I) that included 3,939 farm households and 13,144 persons who were interviewed about their injury experience and farming operation-related exposures during 1990. Rates were calculated for sociodemographic variables and various exposures pertinent to large farm machinery (excluding tractors). Multivariate analyses were conducted using logistic regression, based on a model developed a priori and further confirmed using backward stepwise logistic regression. Among the total farming-related injury events (n = 764), 151 (20%) were related to large machinery use (1,127 injured persons per 100,000 persons per year). Through multivariate analyses, several variables were associated with elevated rate ratios that were important in both models: hours worked per week on the farm (40-59, 60-79, 80+); operation of an auger; field crops as the enterprise requiring the most time; and male gender. In addition, in the backward stepwise model, certain marital status categories (married; separated/widowed/divorced) were also associated with elevated rate ratios that were important. The majority of injury events occurred while persons were lifting, pushing, or pulling (21%), adjusting a machine (20%), or repairing a machine (17%). While only 5% of the cases were hospitalized, 79% required some type of health care. Among all injured persons, 34% were restricted from regular activities for 1 week or more and 19% were restricted for 1 month or more; 25% continued to have persistent problems. In summary, the RRIS-I permitted one of the most comprehensive studies of agricultural machinery-related injuries, to date. The findings indicate that these injuries represent a significant problem, based on the relevant rates, potential risk factors, and consequences from trauma.

Identification of the East African Strain of Sweet Potato Chlorotic Stunt Virus as a Major Component of Sweet Potato Virus Disease in Southern Africa.

Sweet potato virus disease (SPVD) is the most damaging disease of sweet potato Ipomoea batatas (L.) Lam. in Africa. It is caused by sweet potato feathery mottle potyvirus (SPFMV) plus either the West African strain of sweet potato chlorotic stunt crinivirus (Closteroviridae) (SPCSV-WA) (2) or the serologically distinct and apparently more severe East African strain (SPCSV-EA) (1). Typical symptoms of SPVD include severe plant stunting, leaf distortion, chlorosis, mosaic, or vein clearing (1). During a survey done in February 1998 of 48 farmers' fields in Lusaka Province and North Western Province of Zambia, sweet potato plants with typical SPVD symptoms were observed. Incidence was generally 1 to 5% but occasionally >20%. To determine which viruses (SPFMV, SPCSV-EA, SPCSV-WA) were present in symptomatic plants, enzyme-linked immunosorbent assays (ELISAs) were done on leaf sap extracts. Twenty-two SPVD-affected plants from Lusaka Province and 15 from North Western Province were tested and SPFMV and SPCSV-EA (but not SPCSV-WA) were detected in all samples. SPCSV-EA by itself may cause purpling or yellowing of lower or middle leaves (1). Eight plants showing these symptoms were collected from North Western Province, and SPCSV-EA only was detected in six of the samples. SPVD was also observed in a 1997 survey of crops near Antsirable, Madagascar; incidence was generally <1% but occasionally >20%; SPFMV and SPCSV-EA, but not SPCSV-WA, were detected in two SPVD samples tested. Our results are the first report of SPCSV in southern Africa. SPVD in the regions surveyed appears to be due to SPFMV and SPCSV-EA; SPCSV-WA was not detected. References: (1) R. W. Gibson et al. Plant Pathol. 47:95, 1998. (2) G. A. Schaefers and E. R. Terry. Phytopathology 66:642, 1976.

Leukemia and non-Hodgkin's lymphoma and residential proximity to industrial plants.

The risks of developing leukemia and non-Hodgkin's lymphoma from living near industrial facilities were evaluated among men from Iowa and Minnesota in a population-based, case-control study. We found a statistically significant increase in the risk of developing non-Hodgkin's lymphoma (RR = 1.4) and a slight, nonsignificant excess for leukemia (RR = 1.2) among individuals who lived .8-3.2 km (1/2-2 miles) from a factory. Risks were greater for certain histologic types: follicular lymphoma (RR = 1.5), acute lymphocytic leukemia (RR = 5.4), and acute myelocytic leukemia (RR = 2.2). For non-Hodgkin's lymphoma (but not for leukemia), the relative risks for those living within .8 km (1/2 mile) of a factory were similar or slightly larger than for those living .8-3.2 km (1/2-2 miles) from a factory. Risks did not increase with duration of residence near a factory. The elevated risks of non-Hodgkin's lymphoma were particularly associated with residing near stone, clay, or glass industry facilities. The risk of developing leukemia was greater among persons who resided near chemical and petroleum plants. These preliminary findings raise the possibility that general environmental exposure associated with certain industrial activities may elevate the risk of developing leukemia and non-Hodgkin's lymphoma. Evaluation of data on proximity to industrial plants from studies in other geographic locations is needed to determine whether our results represent a meaningful association.

Perspectives on faculty clinical practice: views of occupational therapy curriculum chairpersons and faculty members.

OBJECTIVE: This study investigated whether and how faculty clinical practice (FCP) was being implemented in occupational therapy professional education programs. METHOD: Chairpersons and faculty members from all accredited entry-level occupational therapy curricula in the United States were asked to complete questionnaires about their involvement in FCP. The chairperson questionnaire consisted of primarily closed-ended questions that addressed the organization of faculty practice within their programs, whereas the faculty questionnaire was primarily open-ended and addressed faculty members' individual involvement in FCP as well as the perceived benefits and drawbacks. Responses were analyzed for 39 program chairpersons and 136 faculty members were analyzed. RESULTS: Twenty-five chairperson respondents reported that their educational program had FCP, and 44 faculty respondents indicated involvement in FCP during the past year. FCP was more prevalent in public-funded institutions and academic health centers. Faculty members primarily engaged in FCP in order to stay current, enhance teaching, and develop networks. They reported increased credibility with students as an important benefit of clinical practice. The primary reasons faculty members did not engage in clinical practice were insufficient time and institutional policies. CONCLUSION: Although many faculty members in occupational therapy education programs value clinical practice as a part of their educator role, it is necessary to negotiate responsibilities and rewards to prevent role overload and comply with institutional policies.