PubMed Health⌕ Search

Biomedical subjects

J C Snyder

Publications and source records attributed to J C Snyder.

At least 19 recordsLinked to original sources
PubMed2004

Effects of culturing on the population structure of a hyperthermophilic virus.

The existence of a culturing bias has long been known when sampling organisms from the environment. This bias underestimates microbial diversity and does not accurately reflect the most ecologically relevant species. Until now no study has examined the effects of culture bias on viral populations. We have employed culture-independent methods to assess the diversity of Sulfolobus spindle-shaped viruses (SSVs) from extremely hyperthermal environments. This diversity is then compared to the viral diversity of cultured samples. We detected a clear culturing bias between environmental samples and cultured isolates. This is the first study identifying a culture bias in a viral population.

Archaeal Viruses↗
PubMed2003

Potential of solid phase extraction disks to aid determination of dislodgeable foliar residues of chlorpyriphos, malathion, diazinon, and acephate.

The utility of solid phase extraction (SPE) for concentrating four organophosphate insecticides from solutions of water and sodium dioctyl sulfosuccinate, a surfactant, was evaluated. Reverse phase (C18, octadecyl bonded silica) sorbent in the form of a disk was the SPE medium evaluated. Chlorpyriphos, malathion, and diazinon, but not acephate, were retained on and eluted from the SPE disks. For pesticides that were retained on SPE disks, recoveries from the disks were equal to or higher than recoveries achieved by solvent partitioning. Dislodgeable foliar residues of acephate were successfully concentrated for analysis by lyophilization of water-surfactant solutions. Recoveries of pesticides from SPE disks stored at -15 degrees C for one week were equal to or higher than those of pesticides stored in water-surfactant for one week at -15 degrees C. Malathion- and diazinon-fortified samples in watersurfactant and on SPE disks were prepared in one state and shipped for analysis in another state. Pesticides in the water-surfactant samples were concentrated by solvent partitioning and were underestimated by 41% (diazinon) and 16% (malathion). Conversely, diazinon samples on the SPE disks were on average underestimated by 3% and malathion was overestimated by an average of 55%. The overestimation of malathion was attributed to a matrix effect during analysis associated with the presence of surfactant, which was retained on and subsequently eluted from the SPE disks. The retention of surfactant by the SPE disks and its subsequent elution may considerably limit their usefulness in determination of dislodgeable foliar residues.

Chemistry Techniques, Analytical↗
PubMed2001

Pyrethrins and piperonyl butoxide residues on potato leaves and in soil under field conditions.

Residues of pyrethrin-I (Py-I) and pyrethrin-II (Py-II), the major insecticidal components of the pyrethrum daisy (Tanacetum cinerariifolium) as well as residues of piperonyl butoxide (PBO, a pyrethrum synergist) were determined in soil and on potato foliage grown under field conditions. A pyrethrum formulation (Multi-Purpose Insecticide) containing the three active ingredients was sprayed twice at the rate of 6 lbs of formulated product.acre(-1) ( 5.4 and 27.2 g A.I. of pyrethrin and PBO, respectively) on potato foliage during the growing season. In soil, three management practices (yard waste compost, grass filter strips, and a no mulch treatment) were used to study the impact of surface soil characteristics on the amount of pyrethrins (Pys) and PBO retained in soil. Soil samples and potato leaves were collected at different time intervals after spraying. Samples were purified and concentrated using solid-phase extraction columns containing C18-Octadecyl bonded silica. Residues were quantified by high-performance liquid chromatograph equipped with a UV detector. The first spray resulted in mean initial deposits of 0.18, 0.40, and 0.99 microg.g(-1) potato leaves for Py-I, Py-II, and PBO, respectively. Residues in soil were higher in compost treatments compared to no mulch treatments.

Agriculture↗
PubMed2001

Sustainable soil management practices and quality of potato grown on erodible lands.

Land productivity can decline when top soil is lost. In Kentucky, limited resource farmers often produce vegetable crops on erodible lands. The objectives of this study were 1) to quantify the impact of three soil management practices (SMPs) on quantity of potato produced on erodible land, 2) to evaluate the impact of pyrethrin and azadirachtin insecticides on potato tuber quality, and 3) to assess the impact of yard waste compost on the chemical composition (ascorbic acid, free sugars, phenol contents) of potato tubers. Potatoes (Solanum tuberosum L. cv. Kennebec) were grown in a silty loam soil of 10% slope. Plots (n= 18) were 3.7 m wide and 22 m long (10% slope), with metal borders of 20 cm above ground level. Two botanical insecticides, Multi-Purpose Insecticide (containing pyrethrin 0.2%) and Neemix 4EC (containing 0.25% azadirachtin) were sprayed twice on potato foliage during each of two growing seasons (1997 and 1999) at the recommended rates of 6 lbs and 2 gallons.acre(-1), respectively. The SMPs were tall fescue strips (FS) intercropped between each two potato rows, soil mixed with yard waste compost (COM) and no-mulch (NM) treatment (roto-tilled bare soil). The experimental designwas a 2 x 3 x 3 factorial with main factors of two insecticides and three SMPs replicated three times. Average potato yield was lowest in NM and FS and highest in COM treatments. Yield obtained from the bottom of the plots was greater than that obtained from the top of plots. Tuber defects (rot, scab, sun green, hollow heart, necrosis, and vascular discoloration) were significantly different between the two growing seasons. The two insecticidal treatments did not have much influence on potato yield or tuber defects. Tubers obtained from tall fescue treatments had low levels of ascorbic acid and reducing sugars compared to compost treatments.

Insecticides↗
PubMed1992

Orthostatic hypotension: a potential side effect of psychiatric medications.

1. Orthostatic hypotension is a major underrecognized side effect of antipsychotic and antidepressant medications. It has been associated with falls, fractures, and lacerations, particularly in the elderly. 2. Orthostatic vital signs need to be routinely measured in patients susceptible to orthostasis. A standardized procedure should be available and must include a stable baseline measurement in the supine position at 30 seconds and 2 minutes in the sitting or standing position. 3. Measures to counteract orthostasis include nutrition/hydration assessment, environmental safety, and patient teaching.

Antidepressive Agents↗
PubMed1991

When staff are assaulted. A nursing consultation support service.

Increasing patient to staff assaults led to the development of a Nursing Consultation Service, which can respond to the needs of assault victims and set the tone for institutional attitudes of nonblaming concern. A member of the consultation service meets with each known assault victim to review the incident, offer support, and provide assistance in addressing issues aroused by the incident. Implementation of this service and the use of a continuous monitor to track assault incidents is vital to highlight problem areas and develop assault prevention strategies.

Assertiveness↗
PubMed1986

Consensus and difference among hospital professionals in evaluating child maltreatment.

The decision-making process in suspected cases of child maltreatment involves reaching interprofessional consensus. Interprofessional consensus in seriousness ratings of maltreatment incidents for the welfare of the child was examined by surveying 39 case vignette ratings by 295 pediatric hospital professionals from five occupations. The survey instrument was derived from research by Giovannoni and Becerrra (1979). An exploratory factor analysis yielded five categories of maltreatment: physical abuse, sexual abuse, general failures in care, minor neglect/discipline, and lifestyles/values. A sixth category, parental sexual preference, was rated not very serious and did not appear to belong in the maltreatment domain. Nurses and social workers rated incidents as most serious, differing significantly from psychiatrists and, often, from physicians and psychologists. Professions agreed on rank ordering of categories by seriousness. Variables such as sex, parenthood status, years of experience, and medical specialty showed some relationship to ratings within some professional groups.

Adult↗