RESUMEN

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.

RESUMEN

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.

RESUMEN

OBJECTIVES: The purpose of this effort was to identify the incidence and consequences of both farming and non-farming related injuries and the potential risk factors for farming related injuries among children and youth, aged 0-19 years, who lived in farm households in a large region of the United States. METHODS: Data were collected from randomly selected farm households during 1990. Rates and rate ratios with 95% confidence intervals were calculated for sociodemographic and exposure variables. Multivariate analyses were conducted, using a priori and backward stepwise logistic regression models. RESULTS: Within the population of 3,939 farm households and 13,144 persons, children and youth accounted for 33%. Injury rates for farming and non-farming sources, respectively, were 1,683 and 6,980 per 100,000 persons. Animals (40%) were the primary sources of the farming operation related injuries; sports/recreation sources (61%) were associated primarily with non-farming related injuries. Of the farming and non-farming operation related injury cases, 83% and 90%, respectively, required some type of health care; moreover, 17% and 24%, respectively, were restricted from regular activities for one month or more. Through multivariate analyses, important increased rate ratios were observed for operating a tractor, working with dairy cattle, and being male. Increased rate ratios for working with beef cattle, operating a harvester, and living on a farm where there were all terrain vehicles in use, and a decreased rate ratio for living on a farm where there were sheep, appeared suggestive. CONCLUSIONS: Based on the relevant rates, injury consequences, and potential risk factors identified, injuries to children and youth on farms represent a significant problem. Future analytic studies are essential to identify more specific risk factors that can serve as a basis for development of appropriate intervention efforts. Given the population at risk, and the opportunity for intervention in this unique occupational setting, many of these injuries may be readily amenable to prevention efforts.

Asunto(s)

RESUMEN

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.

Asunto(s)

RESUMEN

Sweet potato feathery mottle virus (SPFMV, genus Potyvirus) infects sweet potatoes (Ipomoea batatas) worldwide, but no sequence data on isolates from Africa are available. Coat protein (CP) gene sequences from eight East African isolates from Madagascar and different districts of Uganda (the second biggest sweet potato producer in the world) and two West African isolates from Nigeria and Niger were determined. They were compared by phylogenetic analysis with the previously reported sequences of ten SPFMV isolates from other continents. The East African SPFMV isolates formed a distinct cluster, whereas the other isolates were not clustered according to geographic origin. These data indicate that East African isolates of SPFMV form a genetically unique group.

Asunto(s)

RESUMEN

When infecting alone, Sweet potato feathery mottle virus (SPFMV, genus Potyvirus) and Sweet potato chlorotic stunt virus (SPCSV, genus Crinivirus) cause no or only mild symptoms (slight stunting and purpling), respectively, in the sweet potato (Ipomoea batatas L. ). In the SPFMV-resistant cv. Tanzania, SPFMV is also present at extremely low titers, though plants are systemically infected. However, infection with both viruses results in the development of sweet potato virus disease (SPVD) characterized by severe symptoms in leaves and stunting of the plants. Data from this study showed that SPCSV remains confined to phloem and at a similar or slightly lower titer in the SPVD-affected plants, whereas the amounts of SPFMV RNA and CP antigen increase 600-fold. SPFMV was not confined to phloem, and the movement from the inoculated leaf to the upper leaves occurred at a similar rate, regardless of whether or not the plants were infected with SPCSV. Hence, resistance to SPFMV in cv. Tanzania was not based on restricted virus movement, neither did SPCSV significantly enhance the phloem loading or unloading of SPFMV. It is also noteworthy that SPVD is an unusual synergistic interaction in that the potyvirus component is not the cause of synergism but is the beneficiary. It is hypothesized that SPCSV is able to enhance the multiplication of SPFMV in tissues other than where it occurs itself, perhaps by interfering with systemic phloem-dependent signaling required in a resistance mechanism directed against SPFMV.

Asunto(s)

RESUMEN

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.

RESUMEN

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.

Asunto(s)

RESUMEN

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.

Asunto(s)

RESUMEN

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.

RESUMEN

This case-control study used the National Crime Victimization Survey database (a national sample of housing addresses) to examine sociodemographic risk factors for becoming a victim of work-related robbery and assault. Cases (N = 267) reported having been violently victimized in the previous 6 months. Controls (N = 1,783) were chosen from all nonvictims of violent crime at the end of the 6-month period. Risk factors varied by type of victimization, and differences were evident between men and women. Men less than 45 years of age had an increased risk for assault [odds ratio (OR) = 2.0-2.7], compared with those 55 years of age and older; and those with a family income of less than $40,000 had an increased risk for assault (OR = 1.7-1.9), compared with those having a family income of $50,000 or more. We found a decreased risk for those with a high school education (OR = 0.6), compared with those with some college education. For women, an increased risk was seen for ages 16-18 years (OR = 3.3) and 25-34 years (OR = 2.3), compared with those 55 years of age or older. Women who were divorced or separated (OR = 4.4) and never-married (OR = 2.1) were at higher risk than women who were married. We found a decreased risk for nonwhites (OR = 0.5), compared with whites.

Asunto(s)

Asunto(s)

RESUMEN

Animals have been implicated as an important source of injury for farm household members. Little is known, however, about the specific activities associated with the animal/livestock operations that place a person at increased or decreased risk for injuries. The primary aim of this case-control study was to identify which dairy cattle operation activities (that is, milking, feeding, cleaning barns, trimming and treating feet, dehorning, assisting with difficult calvings, and doing treatments) were associated with an increased or decreased risk of injury. We found milking to have the greatest increase in risk for injury. The ratios for increasing hours per week spent at milking (0, 1-10, 11-20, 21-30, 31-63) were 1.0, 2.3, 5.5, 10.9, and 20.6, respectively. We also found an increased rate ratio associated with trimming or treating hooves (rate ratio = 4.2).

Asunto(s)

RESUMEN

Brain injury, a leading cause of mortality, morbidity and disability in the United States, has serious consequences and substantial costs. Although previous studies have assessed a variety of outcomes subsequent to brain injury, documentation of performance prior to brain injury using a case-control approach has not been included; preinjury performance differences may confound the estimate of the effects of brain injury on performance. The primary objective of this study was to compare academic performance before and after brain injury in a population of university undergraduate students to determine the extent to which the academic career of the brain-injured person was altered from what would have been expected in the absence of such an injury. Cases included all undergraduate students in a major university, between the ages of 17 and 27, who incurred a brain injury requiring hospitalization between 1980 and 1984 (n = 99). Two comparison groups were used to determine whether changes in academic performance were specifically related to brain injuries or injuries in general: (1) injured controls, i.e. 121 students between the ages of 17 and 27 years, hospitalized for injuries other than to the central nervous system, and (2) uninjured academic controls, i.e. 198 students with out injuries requiring hospitalization during the study period, matched 2:1 to the brain-injured students by age, gender, and completed course credits categorized as < 90, > or = 90. Although there were no differences when the total groups, including both males and females, were compared, there was a significant pre- to postinjury decrease in the grade point average for female cases when compared to their uninjured academic controls (p < 0.02). This difference was related to the effects of brain injury, and not to the effects of injury in general. No such difference was observed for the males. There were also no differences when the total groups, including males and females, were compared relevant to return to school. However, a significantly higher proportion of the female cases, compared with their uninjured academic controls, did not return to school after their injury; similar findings were identified for the injured controls as well. Thus, these differences were not specific to brain injury but rather to injury in general. In spite of this observation, the difference between female cases who returned and those who did not return was associated with neurological deficits, especially upper left limb motor deficits, as the time of hospital discharge. The findings from this effort are suggestive of gender differences in the consequences of brain injury and serve as a basis for further studies to evaluate the magnitude of this problem.

Asunto(s)

RESUMEN

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.

Asunto(s)

RESUMEN

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.

Asunto(s)

RESUMEN

Proxy respondents have often been used in case-control studies of cancer and pesticides. To evaluate the effect of exposure misclassification, we compared data collected during 1981-1983 from participants interviewed for a case-control study of leukemia and non-Hodgkin's lymphoma with data collected during 1990-1991 from proxy respondents for participants who died or became incompetent since the initial interview (328 self-proxy pairs). As questions increased in detail, agreement percentages decreased. Agreement percentages were highest for demographic and general farming information (averages = 88-90%) and lowest for specific pesticide use (averages = 68-74%). Generally, odds ratios calculated from proxy respondent data were less than those from self-respondent data; however, several exceptions occurred. The findings indicate that pesticide data provided by proxy respondents will not necessarily result in the same estimate of risk and/or lead to the same conclusions as data provided by self-respondents.

Asunto(s)

RESUMEN

A case-control study was conducted in the Minneapolis-St Paul (Minnesota, United States) area to assess the role of dietary factors in the etiology of pancreatic cancer. Cases were White males aged 40 to 84 whose death certificate listed pancreatic cancer (exocrine only). White male controls were ascertained through random-digit dialing. Family members were interviewed about the subject's dietary usage in the two years prior to death (cases, n = 212) or prior to interview (controls, n = 220). Energy-adjusted, nutrient-intake, risk estimates were calculated. Among all respondents, negative trends were observed for polyunsaturated fat, linoleic acid, vitamin C, and beta-carotene. Positive trends were observed for riboflavin and retinol. Point estimates were, in general, comparable between the analyses of all respondents and spouse-only respondents. The nutrients associated with a decreased risk for pancreatic cancer occur primarily in vegetables and fruits, of which the consumption of cruciferous and beta-carotene-rich vegetables and citrus fruits provided the greatest reduction in risk.

Asunto(s)

RESUMEN

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.

Asunto(s)