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Biomedical subjects

S J Reynolds

Publications and source records attributed to S J Reynolds.

At least 37 records · Page 2Linked to original sources
PubMed1999

An evaluation of the effectiveness of lead paint hazard reduction when conducted by homeowners and landlords.

This research project was conducted in collaboration with the Iowa Department of Public Health to evaluate whether property owners who follow recommended procedures for lead-based paint removal/repair can do the work safely and effectively. This study included 29 homes where a lead-based paint hazard had been identified and lead-based paint was removed or repaired (hazard reduction). Exposure evaluation included pre-project surface dust wipe sampling, air monitoring during lead-based paint removal, post-project surface dust wipe sampling, and pre- and post-project blood samples from adult study participants. The comparison of surface dust wipe samples taken before and after lead paint hazard reduction was used to evaluate the effectiveness of lead paint hazard reduction. The lead loadings on window sill surfaces in the work area were significantly lower after completion of the project (p = 0.04), and the lead-based paint removal did not contaminate the adjoining living area. The proportion of homes with surface dust lead loading exceeding Department of Housing and Urban Development (HUD) clearance standard was 73 percent pre-project and 38 percent post-project. Personal airborne exposures during lead removal activities (geometric mean = 59.3 micrograms/m3) reinforce the need for respiratory protection and good hygiene. There was no difference in adult pre-/post-blood levels, indicating that participants did remove lead in a safe manner with respect to their own exposures. The results indicate that hazard reduction can be done effectively when recommended procedures for the removal of lead-based paint are followed.

Adult↗
PubMed1998

Viewer-centered temporal biasing of 3-D rotation percepts.

The perceived direction of rotation of a 3-D cloud of dots can be biased by a prior rotation (Jiang, Pantle, and Mark, 1998 Perception & Psychophysics 60 275-286). In a series of experiments, it is shown that the temporal rotation bias is reversed by a 180 degrees change of head orientation between two rotation sequences; i.e. the perceived direction of rotation reverses for the second of two sequences when head orientation is changed. The bias is, therefore, viewer-centered. Perceptual reversals are not obtained when the orientation of the head is changed and returned to its original position between rotation sequences. It was also found that the viewer-centered bias combined additively with viewer-independent near-far luminance information. Finally, the bias was manifest when 3-D depth was re-established, but not maintained, between rotation sequences. A model, in descriptive and flowchart forms, is used to explain the integration of world-centered information and a viewer-centered temporal bias on the presence/absence of perceptual reversals of the rotating virtual sphere. In the model, the temporal bias is the result of the coupling of depth values to persisting 2-D retinal motion signals.

Computer Graphics↗
PubMed1997

Distinct cis-acting sequences are required for the germination and sugar responses of the cucumber isocitrate lyase gene.

Recent data have shown that distinct DNA sequence elements direct the germination and sugar responses of the cucumber (Cucumis sativus, L.) malate synthase (Ms) gene (Sarah et al. (1996) Mol. Gen. Genet., 250, 153-161). Such information is, however, lacking for the isocitrate lyase (Icl) gene which is coordinately regulated with Ms. Deletions from the 5' end of the Icl promoter were therefore created specifically to address this question. Analysis of expression in seeds of transgenic Nicotiana plumbaginifolia plants showed that whereas a promoter sequence of 2.9 kilobases (kb) produced a normal germination response, deletion to -1568 base pairs (bp) dramatically reduced this response. Examination of the sugar response employed a transgenic cucumber root system. In this case, the 2900 bp and 1568 bp promoters both gave a strong sugar response, but further deletion to -1367 bp eliminated the response. Therefore, the germination and sugar responses of the Icl gene require distinct cis-acting elements, located respectively upstream and downstream of -1568 bp. This observation is consistent with distinct signal transduction systems regulating gene expression in each case.

Cucumis sativus↗
PubMed1997

Lead poisoning among construction workers renovating a previously deleaded bridge.

This study evaluated lead poisoning among construction workers renovating a previously deleaded bridge. Twelve of 44 tested workers had blood leads exceeding 20 micrograms/dL. One was 50 micrograms/dL and two exceeded 40 micrograms/dL. Following medical intervention, blood leads dropped significantly, while ZPPs did not. Renovation released lead that had been inaccessible during deleading. Workers did not use engineering controls or respirators, change clothes, wash hands, or shower. Intervention included a lead-compliance program with provisions for exposure evaluation, training, hygiene, and engineering controls. Construction contractors and workers need to be aware that deleading of bridges and other structures may not remove lead from inaccessible locations. In particular, owners of these structures should specify provisions for anticipating and controlling this hazard in contracts.

Health Education↗
PubMed1997

Impaired vision for binocular tasks after unilateral optic nerve regeneration in the frog Litoria moorei.

Behavioural responses to objects in the binocular field were examined in frogs with one regenerate and one intact optic nerve. Data were compared to those for normal controls and for frogs with vision via one intact optic nerve. During prey acquisition, frogs with regenerated optic nerves underestimated the distance to the prey on their first strike; as a consequence, the regenerate series made several attempts to achieve a successful prey capture. By contrast, normal frogs and those using only one eye struck accurately at the prey and usually captured it on the first attempt. However, frogs using only one eye struck from a closer distance than either the regenerate or normal series. Frogs with regenerated optic nerves also made more errors than either of the other series when leaping through a set of closely spaced horizontally aligned rods. Our results show that prey capture and the negotiation of horizontally aligned rods is impaired in animals using one regenerated and one intact optic nerve as compared to both normal frogs and those using only one eye. We suggest that the poor visual performance for frogs with one regenerated and one intact optic nerve for tasks presented in the binocular field is related to the integration of a degraded and a normal image within the visual centres.

Animals↗
PubMed1997

Field evaluation of endotoxin air sampling assay methods.

This study tested the importance of filter media, extraction and assay protocol, and bioaerosol source on the determination of endotoxin under field conditions in swine and poultry confinement buildings. Multiple simultaneous air samples were collected using glass fiber (GF) and polycarbonate (PC) filters, and these were assayed using two methods in two separate laboratories: an endpoint chromogenic Limulus amebocyte lysate (LAL) assay (QCL) performed in water and a kinetic chromogenic LAL assay (KQCL) performed in buffer with resistant-parallel line estimation analysis (KLARE). In addition, two aqueous filter extraction methods were compared in the QCL assay: 120 min extraction at 22 degrees C with vigorous shaking and 30 min extraction at 68 degrees C with gentle rocking. These extraction methods yielded endotoxin activities that were not significantly different and were very highly correlated. Reproducibility of endotoxin determinations from duplicate air sampling filters was very high (Cronbach alpha all > 0.94). When analyzed by the QCL method GF filters yielded significantly higher endotoxin activity than PC filters. QCL and KLARE methods gave similar estimates for endotoxin activity from PC filters; however, GF filters analyzed by the QCL method yielded significantly higher endotoxin activity estimates, suggesting enhancement of the QCL assay or inhibition of the KLARE asay with GF filters. Correlation between QCL-GF and QCL-PC was high (r = 0.98) while that between KLARE-GF and KLARE-PC was moderate (r = 0.68). Analysis of variance demonstrated that assay methodology, filter-type, barn-type, and interactions between assay and filter-type and between assay and barn-type were important factors influencing endotoxin exposure assessment.

Air Pollution, Indoor↗
PubMed1997

Laboratory comparison of vacuum, OSHA, and HUD sampling methods for lead in household dust.

The goals of this project were to evaluate and compare the efficiency and reproducibility of three methods for sampling lead-containing dust in homes. Lead-containing dust was generated in a 1-m3 chamber and uniformly deposited onto surfaces typically found in the home (painted wood, unpainted wood, varnished wood, linoleum, and carpet). Trials with three levels of lead concentrations were performed for each surface. Replicate, side-by-side, surface samples were collected using the Occupational Safety and Health Administration (OSHA) wipe method, the Department of Housing and Urban Development (HUD) wipe method, and a vacuum-filter method. Samples were digested with nitric acid and analyzed using graphite furnace atomic absorption spectroscopy per National Institute of Occupational Safety and Health Method 7105. Recovery for the HUD method was consistently the highest on most surfaces (linoleum, 89.9 to 108.9%; painted wood, 71.2 to 153.7%; unpainted wood, 25.3 to 76.0%; varnished wood, 8.7 to 165.6%). On carpet the vacuum method had a significantly higher recovery (26.2 to 47.8%). For all sampling methods the percent recovery depended on type of surface and lead concentration. The reproducibility of percent recovery for the HUD (pooled coefficient of variation [CV] = 0.22) and OSHA (pooled CV = 0.27) methods was lower than that of the vacuum method (pooled CV = 0.46), though not statistically significant. Reproducibility for all methods did not vary significantly over surface type or lead concentration. Overall, the HUD method yielded the most accurate measurements, with recoveries closest to 100%. It was also more durable than the OSHA method, where Whatman filters were observed to tear.

Child, Preschool↗
PubMed1997

Health impairments among refuse derived fuel workers.

We conducted this study to address concerns regarding a perceived increase in bronchitis, skin rashes, and diarrhea and long term health effects in workers at two Refuse Derived Fuel (RDF) processing plants. We abstracted medical records to assess symptom occurrence, and to identify spirometry and lab abnormalities. Overall FEV1 and FVC showed no decrease over time for workers with more than five years of exposure. The primary self reported symptoms were low back pain and headaches followed by skin rashes, colds, 'flu', hay fever and ear problems. Conclusions from this analysis are limited by lack of standardized protocols or a control group. However, results from this analysis pointed out potential occupational health problems among RDF workers for future epidemiological and environmental studies.

Adult↗
PubMed1996

Distinct cis-acting elements direct the germination and sugar responses of the cucumber malate synthase gene.

The malate synthase gene (ms) promoter in cucumber (Cucumis sativus L.) was investigated with the aim of distinguishing DNA sequences mediating regulation of gene expression by sugar, and expression following seed germination. Promoter deletions were constructed and their ability to direct expression of the beta-glucuronidase (gus) reporter gene was investigated in transgenic Nicotiana plumbaginifolia. Gene expression was assayed in germinating seeds and developing seedlings (the germination response) and in seedlings transferred from light into darkness with and without sucrose (the sugar response). As progressively more of the promoter was deleted from the 5' end, first the sugar response and then the germination response was lost. Thus, distinct regions of the promoter are required for carbohydrate control and for regulation of gene expression in response to germination. Sequence comparisons of the ms promoter with that of the isocitrate lyase gene (icl) of cucumber have previously identified four IMH(ICL-MS-Homology) sequences. One such sequence, IMH2, is shown here to be implicated in the sugar response of the ms gene. The 17 bp sequences which when deleted from the ms gene results in loss of the germination response, contains a 14 bp sequence which is similar to a sequence in the icl promoter, which we refer to as IMH5. Furthermore, this sequence has similarity with amdI9-like sequences in filamentous fungi, which confer facB-mediated acetate inducibility on several genes, including those encoding ICL and MS.

Base Sequence↗
PubMed1996

Longitudinal evaluation of dose-response relationships for environmental exposures and pulmonary function in swine production workers.

Studies describing respiratory health hazards for workers in swine production facilities have been published in the United States, Sweden, Canada, the Netherlands, and Denmark. Up to 50% of these workers experience bronchitis, organic dust toxic syndrome, hyper-reactive airways disease, chronic mucous membrane irritation, and other respiratory effects. These studies clearly point to the fact that this occupational environment poses a significant health risk hazard, and that control methods are needed to protect the worker. Before precise control strategies can be developed, implemented, and evaluated, dose-response studies are required to determine acceptable target levels for exposure. A previous manuscript described the development of multiple regression equations characterizing the relationships between environmental exposures and pulmonary response in a cohort of 207 swine producers. Baseline pulmonary function was included as a significant predictor of cross-shift decrements in pulmonary function in addition to personal measurements of dust, endotoxin, and ammonia concentrations. These equations were then used to predict specific exposure levels of dust and ammonia that could be expected to elicit significant decrements in cross-shift pulmonary function. This paper presents the results from analysis of follow-up data obtained on this same cohort 2 years after the initial measurements. At the second measurement period of the study (time-2), swine workers were found to have a mean cross-shift decrease in FEV1 of 2%. Cross-shift change in FEV1 was significantly correlated with personal exposures to total dust, total endotoxin, respirable endotoxin, and ammonia. The magnitude of the decrease in FEV1 was associated with increasing airborne concentrations of these environmental parameters thus confirming the dose-response relationship observed in the initial study (time-1). The correlation of dust with FEV1 changes in workers with more than 6 years of exposure (time-1 data) and more than 10 years of exposure (time-2 data) suggests that dust exposure is an important factor in chronic respiratory disease. Additionally, the correlation of endotoxins with FEV1 changes in the group with less than 6 years exposure (time-2 data) suggests endotoxins may have more significance for subacute respiratory effects. The agreement between observed cross-shift FEV1 changes measured in time-2 with changes predicted using regression equations derived from time-1 data demonstrates a consistent dose-response relationship over time for this cohort of swine production workers. This finding provides further support for conclusions of the previous study that levels of 2.5 mg/m3 (total dust) and 7.5 ppm (ammonia) are reasonable guidelines for occupational exposure limits in this environment.

Adult↗
PubMed1995

Respiratory dysfunction in swine production facility workers: dose-response relationships of environmental exposures and pulmonary function.

Human respiratory health hazards for people working in livestock confinement buildings have been recognized since 1974. However, before comprehensive control programs can be implemented, more knowledge is needed of specific hazardous substances present in the air of these buildings, and at what concentrations they are harmful. Therefore, a medical epidemiological and exposure-response study was conducted on 207 swine producers using intensive housing systems (108 farms). Dose-response relationships between pulmonary function and exposures are reported here. Positive correlations were seen between change in pulmonary function over a work period and exposure to total dust, respirable dust, ammonia, respirable endotoxin, and the interactions of age-of-producer and dust exposure and years-of-working-in-the-facility and dust exposure. Relationships between baseline pulmonary function and exposures were not strong and therefore, not pursued in this study. The correlations between exposure and response were stronger after 6 years of exposure. Multiple regression models were used to identify total dust and ammonia as the two primary environmental predictors of pulmonary function decrements over a work period. The regression models were then used to determine exposure concentrations related to pulmonary function decrements suggestive of a health hazard. Total dust concentrations > or = 2.8 mg/m3 were predictive of a work period decrement of > or = 10% in FEV1. Ammonia concentrations of > or = 7.5 ppm were predictive of a > or = 3% work period decrement in FEV1. These predictive concentrations were similar to a previous dose-response study, which suggested 2.5 mg/m3 of total dust and 7 ppm of NH3 were associated with significant work period decrements. Therefore, dust > or = 2.8 mg/m3 and ammonia > or = 7.5 ppm should be considered reasonable evidence for guidelines regarding hazardous exposure concentrations in this work environment.

Adult↗
PubMed1995

Regulation of expression of the cucumber isocitrate lyase gene in cotyledons upon seed germination and by sucrose.

A 6.5 kb cucumber genomic DNA fragment containing the icl gene was introduced into Nicotiana plumbaginifolia and shown to direct isocitrate lyase (ICL) mRNA synthesis in transgenic seedlings upon germination, in a temporally regulated manner. Two putative icl promoter fragments, of 2900 and 572 bp, were subsequently linked to the GUS reporter gene and introduced into N. plumbaginifolia. Both constructs directed GUS expression after transgenic seed germination, and although the 572 bp fragment gave only 1% of the activity of the 2900 bp fragment, it directed expression in the same cotyledon-specific and temporally regulated pattern. Seedlings were transferred to darkness after 18 days growth in the light, to induce a starvation response. The 2900 bp construct was activated by starvation and repressed by exogenous sucrose, whereas the 572 bp construct was not starvation-responsive. To localize the region of the 2900 bp promoter fragment which is responsible for regulation by sucrose, further deletions were made, linked to GUS, and assayed in a cucumber protoplast transient assay system. Constructs with promoters of 2900, 2142 and 1663 bp were activated by starvation and repressed by sucrose, but promoters of 1142 and 572 bp showed no such response. We conclude that the icl gene promoter contains at least two distinct cis-acting elements, one required for the response to sucrose and the other which participates in expression upon seed germination.

Base Sequence↗
PubMed1995

The isocitrate lyase gene of cucumber: isolation, characterisation and expression in cotyledons following seed germination.

The cucumber (Cucumis sativus L.) genome contains only a single gene encoding the glyoxylate cycle enzyme isocitrate lyase (ICL). The cucumber icl gene has been isolated and sequenced, revealing only two small introns. The predicted amino acid sequence is more than 85% identical to ICL from other higher plants, and contains the C-terminal tripeptide Ser-Arg-Met which resembles a peroxisomal targeting sequence. The icl gene is coordinately expressed with the malate synthase (ms) gene after seed germination in both the light and the dark, suggesting that these genes may contain similar DNA elements regulating transcription. The start of transcription of the icl gene was determined and the DNA sequences upstream compared with the region of the ms gene promoter known to regulate transcription. This comparison revealed a highly conserved DNA sequence at similar positions in each gene.

Amino Acid Sequence↗
PubMed1993

Cross-sectional epidemiological study of respiratory disease in turkey farmers.

This study was a cross-sectional epidemiological investigation of respiratory disease in farmers involved in the turkey growing industry. Pulmonary function tests and health history questionnaires were administered to a total of 95 turkey farmers throughout Minnesota. Respiratory symptoms were greatest during the winter months when exposure to environmental agents was highest. Prevalence of symptoms was higher for smokers, personnel who worked in hen barns, and for persons who had worked in the turkey growing industry for more than 10 years. Pulmonary function was found to decrease during the work day. Also, pulmonary function was lowest for personnel working in hen bars, and for persons who had been employed in the industry for more than 10 years. These data support the association between respiratory disease and exposure to the environment in confinement farm buildings.

Adolescent↗
PubMed1992

Catecholamines in turkeys with alcohol-induced cardiomyopathy.

Although alcoholic cardiomyopathy has been difficult to reproduce in animals, turkeys fed 5% ethanol develop a dilated congestive cardiomyopathy. We therefore used this model to examine the adrenergic response to left ventricular dysfunction induced by alcohol. In normal turkeys, norepinephrine in kidneys decreased markedly with age from 1 day to 2 mo, with a similar but less dramatic decrease in cardiac norepinephrine. By 2 mo, chronic alcohol ingestion depleted cardiac norepinephrine compared with controls (217 +/- 22 vs. 316 +/- 41 ng/g, P < 0.05), even though cardiac norepinephrine is relatively low in turkeys compared with many other animals and humans. Norepinephrine in aorta was also decreased with alcohol administration, but kidney norepinephrine was unaffected. Dopamine was unaltered in any of the organs studied. Plasma norepinephrine is normally high in turkeys with arterial levels greater than venous (2,898 +/- 746 vs. 1,987 +/- 531 pg/ml at 2 mo). Venous plasma norepinephrine did not differ from control (2,595 +/- 547 pg/ml) after 2 mo of alcohol. Thus, as in humans, cardiomyopathy in alcohol-fed turkeys is associated with reduced cardiac norepinephrine, but unlike humans with cardiomyopathy, circulating norepinephrine remains normal.

Aging↗
PubMed1991

Central nervous system myelin: structure, function, and pathology.

Multiple sclerosis (MS) and a number of related distinctive diseases are characterized by the active degradation of central nervous system (CNS) myelin, an axonal sheath comprised essentially of proteins and lipids. These demyelinating diseases appear to arise from complex interactions of genetic, immunological, infective, and biochemical mechanisms. While circumstances of MS etiology remain hypothetical, one persistent theme involves recognition by the immune system of myelin-specific antigens derived from myelin basic protein (MBP), the most abundant extrinsic myelin membrane protein, and/or another equally susceptible myelin protein or lipid component. Knowledge of the biochemical and physical-chemical properties of myelin proteins and lipids, particularly their composition, organization, structure, and accessibility with respect to the compacted myelin multilayers, thus becomes central to the understanding of how and why these antigens become selected during the development of MS. This review focuses on current understanding of the molecular basis underlying demyelinating disease as it may relate to the impact of the various protein and lipid components on myelin morphology; the precise molecular architecture of this membrane as dictated by protein-lipid and lipid-lipid interactions; and the relationship, if any, between the protein/lipid components and the destruction of myelin in pathological situations.

Amino Acid Sequence↗
PubMed1991

Mitochondrial genome organization and expression associated with cytoplasmic male sterility in sunflower (Helianthus annuus).

A comparative investigation of the organization and expression of the mitochondrial genome in fertile and cytoplasmic male sterile (CMS) sunflower (Helianthus annuus) has been undertaken. A region of mitochondrial genome variation between the two phenotypes has been located in the 3' flanking region of the gene encoding the alpha subunit of the F1 ATPase (atpA). Physical mapping and sequence analysis have been used to show that a rearrangement involving an inversion and an insertion has occurred immediately downstream of the atpA coding region in the mitochondrial DNA from sterile sunflower. This rearrangement has resulted in the creation of a new open reading frame (ORFc) which is co-transcribed with atpA in sterile sunflower. In organello labelling of mitochondrial translation products from the two types of sunflower shows that a 15 kDa protein is synthesized by the mitochondria from sterile sunflower but not by those from fertile plants. The ORFc sequence could encode this 15 kDa protein which may be causally related to the CMS phenotype.

Amino Acid Sequence↗