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PubMed1997

Health risk assessment of an industrial site contaminated with polycyclic aromatic hydrocarbons using CalTOX, an environmental fate/exposure model.

This paper presents the results of a risk assessment study made using CalTOX, a multimedia, multiple pathway risk assessment model. The case study is based on the Polycyclic Aromatic Hydrocarbon (PAH) soil contamination resulting from the activities of a natural gas power station over a period of 70 years. It describes model characteristics and input parameters such as physico-chemical properties, landscape description, and human exposure factors. Model simulations and risk estimations corresponding to different remedial scenarios in an industrial zone are also presented. These estimations were based on soil contamination by 16 PAHs in the root-zone and vadose-zone layer. Results show that adult exposure (workers) to contaminated soil will lead to a potential health risk of carcinogenic effects, and to no potential risk of non-carcinogenic effects. On the other hand, the addition of 10 cm of clean soil over the contaminated soil (mitigated scenario) decreases the lifetime cancer risk to an acceptable level. The sensitivity analysis showed that the half-life of benzo[a]pyrene in the root-zone soil is the most sensitive parameter and that it contributes significantly to the variability of the cancer risk estimation. In addition, the cancer risk level of the workers exposed to this substance, as estimated by CalTOX (point estimate) in the mitigated and unmitigated scenario, corresponds approximately to the 95th percentile value obtained by means of Monte-Carlo simulations. Finally, CalTOX has proven to be a valuable tool to predict and elaborate scenarios for the risk management of sites contaminated as a result of industrial activities.

Adult↗
PubMed2002

Chronomodulated chemotherapy: clinical value and possibilities for dissemination in the United States.

Modern medicine has been relatively slow to apply chronotherapeutic principles to standard oncologic practice. Despite the impressive body of evidence supporting the use of chronochemotherapy, with only a rare exception most oncology clinics in the United States lack the expertise and capability to implement it. At the same time, American medicine has increasingly come to recognize the importance of toxicity mitigation, cytoprotection, and quality of life for patients undergoing cancer treatment. However, toxicity mitigation strategies such as chronomodulated infusional chemotherapy and novel cytoprotective agents are not widely embraced by U.S. physicians. This article explores some reasons why this situation exists, including the influence of non-medical biases that may affect management decisions on the application of chemotherapy. The author conducted a survey of U.S. companies representing the three private insurance payers available (HMO, PPO, Indemnity) as well as representatives of Medicare and Medicaid. Responses to the survey confirmed that U.S. insurers do not at present officially reimburse for chronotherapy; however, changes will come about through educational efforts aimed at increasing awareness among insurers as to the clinical benefits and cost-effectiveness of this mode of treatment. At this juncture, the outlook for cancer chronotherapy as a first-line approach to the treatment of metastatic cancer in the United States remains uncertain. Under the current method of insurance reimbursement, the advancement of chronotherapy in the United States is threatened despite evidence that such treatment is both therapeutically sound and cost-effective.

Antineoplastic Agents↗
PubMed2003

Estimation of methane emission from rice cultivation in Korea.

This study focused on estimating a methane (CH4) inventory and developing mitigation options in South Korea, and was performed jointly in an integrated national research program on CH4 from rice fields conducted by three National Agricultural Research Institutes, under the Rural Development Administration during 1993-1997. Methane emissions were measured by a closed chamber method, in rice plots at three locations (Suwon, Iksan, and Milyang) with the single rice cropping system. All experimental data from 5 years of study were summarized and used for calculating nation-wide CH4 emissions. Temperature, soil type, cultural practices, water management, organic matter management, and cultivar selection significantly affected the fluctuations of CH4 emissions. The two most promising mitigation options for reducing emissions were altered water management, in particular mid-season aeration by short-term drainage, and improved organic matter management, by promotion of aerobic degradation through composing or soil incorporation. Annual total CH4 emission in Korea changed from 410Gg in 1990 to 339Gg in 2000, due mainly to a decrease in the cultivated area of paddy rice. If we convert annual CH4 emission to Global Warming Potential as CO2 equivalent, it amounts to 7.1 M CO2 t yr(-1) of greenhouse gas emitted to the atmosphere in 2000 from the rice fields in Korea, which is just 5.3% of the annual CO2 emission from the industry and energy sector. More importantly, the balance between CO2 uptake by photosynthesis and CO2 emission is positive (a net sink), so that rice culture actually has net benefits for the global atmospheric carbon issue. Further reductions in emission amounts, by following recommendations in this article, could make these benefits even greater.

Agriculture↗
PubMed2002

Acculturation and Latino adolescents' substance use: a research agenda for the future.

This paper conducts a review of the literature on acculturation by Latino adolescents to traditional European-American cultural values and its effect on their substance-using behaviors. This review includes a critical analysis of studies that examine the effects of acculturation on the mental wellbeing of Latino adolescents. Recent findings documenting the association between acculturation and substance use among Latino adolescents are discussed. This paper also examines the limitations of the current research and proposes the development of acculturation scales that focus on measuring the role that predominant Latino and American values, attitudes, and norms play in the substance-use behavior of Latino adolescents. Additionally, the author proposes the development of a conceptual framework that accounts for the impact of acculturation-related stress and the mitigating factors affecting such stress on the substance-use behavior of Latino adolescents. The author asserts that understanding the effects of acculturation-related stress and accompanying mitigating factors could begin to explain the increasingly high rates of substance use reported for Latino adolescents. There is a discussion of research gaps and related research issues, and recommendations for future research are also made.

Acculturation↗
PubMed1989

DNA hybridization in animal taxonomy: a critique from first principles.

DNA hybridization is a "distance method" for phylogenetic reconstruction and, as such, shares a set of assumptions, advantages, and problems with other techniques that do not directly employ character data. The technique purports to measure the average percent mismatch of homologous nucleotide sequences between the single-copy genomes of species. This measurement, as any other, is subject to considerations of accuracy and precision. While replicate measurements and technical modifications can improve precision, the accuracy of such measurements is limited by the equivalence of genomes under comparison. Such routine events in genome evolution as gene duplication and deletion may complicate the interpretation of DNA hybridization distances. Beyond measurement limitations, the most serious potential distortions of distances are due to biased sequence sampling and homoplasy. These problems, however, do not necessarily preclude phylogenetic reconstruction, and their effects may be mitigated by numerical corrections. Homoplasy, in particular, is a difficulty faced by all methods of phylogenetic inference. If such distortions can be eliminated, mitigated by correction, or shown to be trivial, pairwise tree-construction strategies should provide reliable estimates of phylogeny.

Animals↗
PubMed2005

Run-to-run control of meal-related insulin dosing.

BACKGROUND: This study was designed to determine if it was feasible to use a run-to-run algorithm to improve postprandial glucose concentrations in individuals with type 1 diabetes mellitus (T1DM). METHODS: Fourteen subjects were recruited for this 10-week study. During the initial phases of the study, the following information was derived for each subject: basal insulin infusion rates, insulin-to-carbohydrate ratios, insulin correction factors for hyperglycemia, and insulin sensitivities. During the final phases, the algorithm was used to suggest preprandial insulin doses, with a goal of bringing the postprandial glucose into a predetermined target range within 3-7 days. RESULTS: In the single-meal phase (phase 5), 33% of the subject-meal responses were convergent in 3-4 days to a clinically acceptable range, 33% always stayed in range, and 33% had divergent responses, incorrect sensitivities, and/or other mitigating circumstances. In the three-meal phase (phase 6), 41% of the subject-meal responses were convergent in 3-4 days to a clinically acceptable range, 26% were always in range, and 33% had divergent responses, incorrect sensitivities, and/or other mitigating circumstances. CONCLUSIONS: Overall, we were able to safely demonstrate that run-to-run control can be used to manage meal-related insulin in subjects with T1DM.

Algorithms↗
PubMed2006

Physiological effects of kaolin applications in well-irrigated and water-stressed walnut and almond trees.

BACKGROUND AND AIMS: Kaolin applications have been used to mitigate the negative effects of water and heat stress on plant physiology and productivity with variable results, ranging from increased to decreased yields and photosynthetic rates. The mechanisms of action of kaolin applications are not clear: although the increased albedo reduces leaf temperature and the consequent heat stress, it also reduces the light available for photosynthesis, possibly offsetting benefits of lower temperature. The objective of this study was to investigate which of these effects are prevalent and under which conditions. METHODS: A 6% kaolin suspension was applied on well-irrigated and water-stressed walnut (Juglans regia) and almond (Prunus dulcis) trees. Water status (i.e. stem water potential, psi(s)), gas exchange (i.e. light-saturated CO2 assimilation rate, Amax; stomatal conductance, g(s)), leaf temperature (T(l)) and physiological relationships in treated and control trees were then measured and compared. KEY RESULTS: In both species, kaolin did not affect the daily course of psi(s) whereas it reduced Amax by 1-4 micromol CO2 m(-2) s(-1) throughout the day in all combinations of species and irrigation treatments. Kaolin did not reduce g(s) in any situation. Consequently, intercellular CO2 concentration (C(i)) was always greater in treated trees than in controls, suggesting that the reduction of Amax with kaolin was not due to stomatal limitations. Kaolin reduced leaf temperature (T(l)) by about 1-3 degrees C and leaf-to-air vapour pressure difference (VPD(l)) by about 0.1-0.7 kPa. Amax was lower at all values of g(s), T(l) and VPD(l) in kaolin-treated trees. Kaolin affected the photosynthetic response to the photosynthetically active radiation (PAR) in almond leaves: kaolin-coated leaves had similar dark respiration rates and light-saturated photosynthesis, but a higher light compensation point and lower apparent quantum yield, while the photosynthetic light-response curve saturated at higher PAR. When these parameters were used to model the photosynthetic response curve to PAR, it was estimated that the kaolin film allowed 63% of the incident PAR to reach the leaf. CONCLUSIONS: The main effect of kaolin application was the reduction, albeit minor, of photosynthesis, which appeared to be related to the shading of the leaves. The reduction in T(l) and VPD(l) with kaolin did not suffice to mitigate the adverse effects of heat and water stress on Amax.

Carbon Dioxide↗
PubMed2001

Changes in driving patterns and worsening depressive symptoms among older adults.

OBJECTIVES: This study examined whether changes in driving patterns-driving cessation and reduction-have negative consequences for the depressive symptoms of older Americans and whether these consequences are mitigated for people with a spouse who drives. METHODS: The project used data from 3 waves of the Asset and Health Dynamics Among the Oldest Old (AHEAD) study. Depressive symptoms were assessed with an abbreviated Center for Epidemiologic Studies-Depression scale. Using 2 models, the project examined how driving cessation and reduction that occurred between Waves 1 and 2 contributed to increases in depressive symptoms between Waves 2 and 3. The first model included the entire sample (N = 5,239), and the second model focused on drivers only (n = 3,543). A third model added interaction terms to the analysis to consider whether respondents who stopped driving but had a spouse who drove were less at risk of worsening depressive symptoms. RESULTS: Respondents who stopped driving had greater risk of worsening depressive symptoms. Drivers who restricted their driving distances before the study began also had greater risk of worsening depressive symptoms, but seemingly less so than the respondents who stopped driving altogether. For respondents who stopped driving, having a spouse available to drive them did not mitigate the risk of worsening symptoms. DISCUSSION: Changes in driving patterns can be deleterious for older people's depressive symptoms. Initiatives for assisting older people should focus on strategies that help them retain driving skills, that prepare them for the possible transition from driver to ex-driver, and that ensure that they have access to mental health therapies if driving changes are imminent.

Activities of Daily Living↗
PubMed2026

Flavonoid biosynthesis mediated by GmF3Hs contributes to drought tolerance in soybean.

Flavonoids are central to abiotic stress responses, yet the specific signaling roles and evolutionary dynamics of flavonoid biosynthetic intermediates in crop drought adaptation remain elusive. Here, we demonstrate that dihydrokaempferol (DHK) and dihydroquercetin (DHQ), specific intermediate products of the soybean flavanone 3-hydroxylases GmF3H1/2, function as potent signaling molecules that mitigate drought stress. Exogenous DHK/DHQ promoted abscisic acid-dependent stomatal closure and enhanced drought tolerance across diverse dicot species, including soybean and tobacco, highlighting a broadly conserved stress-mitigating signaling mechanism. CRISPR/Cas9-generated gmf3hs double mutants exhibited severe drought hypersensitivity due to compromised redox homeostasis and defective stomatal regulation, which could be specifically rescued by DHK/DHQ application. Furthermore, the loss of GmF3H triggered a distinct reproductive trade-off under stress, leading to increased pod initiation but severe filling defects. Multiomics network analysis revealed extensive rewiring of broader stress-responsive pathways and identified upstream transcription factors, among which GmPHL11 directly binds to and activates the GmF3H1 promoter; overexpression of GmPHL11 promoted DHK accumulation and enhanced drought stress tolerance in soybean hairy roots. Finally, population genomic analyses demonstrated that the GmF3H1H1 haplotype, which confers superior enzymatic activity and robust root growth under drought stress, might have undergone positive selection during soybean domestication. Collectively, our findings redefine the role of GmF3H-derived specific intermediates as potent signaling molecules, providing comprehensive mechanistic and evolutionary insights into flavonoid-mediated drought resilience, developmental trade-offs, and molecular breeding in crops.

Drought Resistance↗
PubMed1997

Cloning of rat and human inducible penile nitric oxide synthase. Application for gene therapy of erectile dysfunction.

Erectile dysfunction is mainly due to the inability of the cavernosal smooth muscle of the penis to undergo complete relaxation. In the aging rat model, erectile dysfunction is accompanied by a reduction of penile smooth muscle compliance and, in very old animals, by a decrease in penile nitric oxide synthase (NOS), which is responsible for the synthesis of the mediator of penile erection, nitric oxide (NO). We have investigated whether the stimulation of penile NOS expression by local induction or gene therapy can mitigate erectile dysfunction in the aged rat. A mix of iNOS (inducible NOS) inducers was continuously delivered to the penises of 5- ("adult"), 20- ("old"), and 30- ("very old") mo-old rats for 3-6 days, and the erectile response to electrical field stimulation of the cavernosal nerve was measured. The erectile dysfunction observed in old and very old rats as compared to adult animals was ameliorated by treatment with iNOS inducers. Penile iNOS was detectable in the penis of these rats by Western blot, NADPH diaphorase, and NOS activity assays. Inducible NOS was inducible in vitro in both rat and human corpora cavernosal tissue and in rat penile smooth muscle cells (RPSMC), as shown by Western blots. However, NO synthesis in cavernosal tissue upon iNOS protein induction remained low, indicating that the increased NOS levels were under physiological control. The iNOS cDNA was cloned from induced RPSMC mRNA and generated by reverse transcriptase polymerase chain reaction (RT-PCR) from induced human penile smooth muscle cells and corporal tissue. The coding regions from both the rat (RPiNOS) and human (HPiNOS) penile iNOS showed several amino acid differences from their analogous isoform in nonpenile tissues. RPiNOS cDNA injected into the penis mitigated the aging-associated erectile dysfunction. The iNOS construct was detected in cavernosal tissue by PCR, and its expression by RT-PCR and Western blots. These results open the way for the possible use of NOS isoforms in the management of erectile dysfunction.

Aging↗
PubMed2007

Uncoupling protein-3: clues in an ongoing mitochondrial mystery.

Uncoupling protein (UCP) 3 (UCP3) is a mitochondrial anion carrier protein with highly selective expression in skeletal muscle. Despite a great deal of interest, to date neither its molecular mechanism nor its biochemical and physiological functions are well understood. Based on its high degree of homology to the original UCP (UCP1), early studies examined a role for UCP3 in thermogenesis. However, evidence for such a function is lacking. Recent studies have focused on two distinct, but not mutually exclusive, hypotheses: 1) UCP3 mitigates reactive oxygen species (ROS) production, and 2) UCP3 is somehow involved in fatty acid (FA) translocation. While supportive evidence exists for both hypotheses, the interpretation of the corresponding evidence has created some controversy. Mechanistic studies examining mitigated ROS production have been largely conducted in vitro, and the physiological significance of the findings is questioned. Conversely, while physiological evidence exists for FA translocation hypotheses, the evidence is largely correlative, leaving causal relationships unexplored. This review critically assesses evidence for the hypotheses and attempts to link the outcomes from mechanistic studies to physiological implications. Important directions for future studies, using current and novel approaches, are discussed.

Animals↗
PubMed1997

Urine and plasma catecholamine and cortisol concentrations after myocardial revascularization. Modulation by continuous sedation. Multicenter Study of Perioperative Ischemia (McSPI) Research Group, and the Ischemia Research and Education Foundation (IREF).

BACKGROUND: Cardiopulmonary bypass is associated with substantial release of catecholamines and cortisol for 12 or more h. A technique was assessed that may mitigate the responses with continuous 12-h postoperative sedation using propofol. METHODS: One hundred twenty-one patients having primary elective cardiopulmonary bypass graft (CABG) surgery were enrolled in a double-blind, randomized trial and anesthetized using a standardized sufentanil-midazolam regimen. When arriving at the intensive care unit (ICU), patients were randomly assigned to either group SC (standard care), in which intermittent bolus administration of midazolam and morphine were given as required to keep patients comfortable; or group CP (continuous propofol), in which 12 h of continuous postoperative infusion of propofol was titrated to keep patients deeply sedated. Serial perioperative measurements of plasma and urine cortisol, epinephrine, norepinephrine, and dopamine were obtained; heart rate and blood pressure were recorded continuously, and medication use, including requirements for opioids and vasoactive drugs, was recorded. Repeated-measures analysis was used to assess differences between study groups for plasma catecholamine and cortisol levels at each measurement time. RESULTS: In the control state-before the initiation of postoperative sedation in the ICU-no significant differences between study groups were observed for urine or plasma catecholamine or cortisol concentrations. During the ICU study period, for the first 6-8 h, significant differences were found between study groups SC and CP in plasma cortisol (SC = 28 +/- 15 mg/dl; CP = 19 +/- 12 mg/dl; estimated mean difference [EMD] = 9 mg/dl; P = 0.0004), plasma epinephrine (SC = 132 +/- 120 micrograms/ml; CP = 77 +/- 122 micrograms/ml; EMD = 69 micrograms/ml; P = 0.009), urine cortisol (SC = 216 +/- 313 micrograms/ml; CP = 93 +/- 129 micrograms/ml; EMD = 127 micrograms/ml; P = 0.007), urine dopamine (SC = 85 +/- 48 micrograms; CP = 52 +/- 43 micrograms; EMD = 32 micrograms; P = 0.002), urine epinephrine (SC = 7 +/- 8 micrograms; CP = 4 +/- 5 micrograms; EMD = 3 micrograms; P = 0.0009), and urine norepinephrine (SC = 24 +/- 14 mg; CP = 13 +/- 9 mg; EMD = 11 mg; P = 0.0004). Reductions in urine and plasma catecholamine and cortisol concentrations found for the CP group generally persisted during the 12-h propofol infusion period and then rapidly returned toward control (SC group) values after propofol was discontinued. Postoperative opioid use was reduced in the CP group (SC = 97%; CP = 49%; P = 0.001), as was the incidence of tachycardia (SC = 79%; CP = 60%; P = 0.04) and hypertension (SC = 58%; CP = 33%; P = 0.01), but the incidence of hypotension was increased (SC = 49%; CP = 81%; P = 0.001). CONCLUSIONS: Cardiopulmonary bypass graft surgery is associated with substantial increases in plasma and urine catecholamine and cortisol concentrations, which persist for 12 or more h. This hormonal response may be mitigated by a technique of intensive continuous 12-h postoperative sedation with propofol, which is associated with a decrease in tachycardia and hypertension and an increase in hypotension.

Aged↗
PubMed2001

Anesthetic concentrations of propofol protect against oxidative stress in primary astrocyte cultures: comparison with hypothermia.

BACKGROUND: The extracellular concentration of glutamate in the brain increases after oxidative damage. This increase may be caused, in part, by changes in glutamate transport by astrocytes. The authors hypothesized that propofol and hypothermia mitigate the effects on astrocytes of oxidative stress. METHODS: Primary cultures of rat cerebral astrocytes were subjected to oxidative stress by incubation with tert-butyl hydroperoxide for 30 min, followed by a 30-90-min washout period. The effects of prophylactic (simultaneous with tert-butyl hydroperoxide application) and delayed (administered 30 min after the oxidant) propofol or hypothermia were determined by measuring the uptake of glutamate as well as the release of preloaded d-aspartate (a nonmetabolizable analog of glutamate) and endogenous lactate dehydrogenase (a cytosolic marker). RESULTS: Delayed administration of an anesthetic concentration of propofol (1-3 microm) prevented the inhibition of high-affinity glutamate uptake, stimulation of d-aspartate release, and increase in lactate dehydrogenase release caused by tert-butyl hydroperoxide (1 mm, 37 degrees C). The protective effect of propofol (EC50 = 2 microm) on glutamate uptake was 20-fold more potent than that of alpha-tocopherol (EC50 = 40 microm). Prophylactic hypothermia (28 and 33 degrees C) also protected astrocytes from tert-butyl hydroperoxide. Delayed hypothermia was not protective but did not compromise rescue by propofol. CONCLUSIONS: Clinical levels of propofol and hypothermia mitigate the effects of oxidative stress on astrocytic uptake and retention of glutamate, with propofol having a relatively larger therapeutic window. The ability of these treatments to normalize cell transport systems may attenuate the pathologic increase in extracellular glutamate at synapses and thus prevent excitotoxic neuronal death.

Anesthetics, Intravenous↗
PubMed2004

Propofol attenuates peroxynitrite-mediated DNA damage and apoptosis in cultured astrocytes: an alternative protective mechanism.

BACKGROUND: The concentration of peroxynitrite in the brain increases after central nervous system injuries. The authors hypothesized that propofol, because of its particular chemical structure, mitigates the effects of peroxynitrite-mediated oxidative stress and apoptosis by the induction of heme oxygenase (HO)-1 in primary cultured astroglial cells. METHODS: Primary cultured astroglial cells were incubated for 18 h with a known peroxynitrite donor (3 mm SIN-1) in the presence or absence of propofol (40 microm, 80 microm, 160 microm, and 1 mm). The protective effects of propofol were evaluated by 3(4,5-dimethyl-thiazol-2-yl)2,5-diphenyl-tetrazolium bromide cytotoxicity assay, lactic dehydrogenase release, DNA ladderization by Comet assay, and caspase-3 activation by Western blot analysis. RESULTS: Appropriate propofol concentrations (ranging from 40 microm to 1 mm) significantly increased HO-1 expression and attenuated SIN-1-mediated DNA ladderization and caspase-3 activation. The protective effects of propofol were mitigated by the addition of tin mesoporphyrin, a potent inhibitor of HO activity. The addition of a specific synthetic inhibitor of nuclear factor kappaB abolished propofol-mediated HO-1 induction, suggesting a possible role of this nuclear transcriptional factor in our experimental conditions. CONCLUSIONS: The antioxidant properties of propofol can be partially attributed to its scavenging effect on peroxynitrite as well as to its ability to increase HO-1 expression at higher concentrations, a property that might be relevant to neuroprotection during anesthesia.

Anesthetics, Intravenous↗
PubMed1999

Issues for academic health centers to consider before implementing a balanced-scorecard effort.

Because of changes in the health care environment, it is likely that strategic planning and management will become much more important to academic health centers (AHCs) than in the past. One approach to strategic planning and management that is gaining the considerable interest of health care organizations is the balanced scorecard. Based on a year's experience in examining this management tool, and on early implementation efforts, the authors critically evaluate the applicability of the balanced-scorecard approach at AHCs in relation to two fundamental questions: Does the decentralized nature of most AHCs mitigate the potential usefulness of the balanced-scorecard approach? Are the balanced scorecard's four perspectives (learning and growth, internal; customer; and financial) appropriate for AHCs, which are neither for-profit nor manufacturing organizations? The authors conclude that (1) the unique characteristics of AHCs may mitigate the full benefit of the balanced-scorecard approach, and (2) in cases where it is used, some key modifications must be made in the balanced-scorecard approach to account for those unique characteristics. For example, in a corporation, the key question from the financial perspective is "To succeed financially, how should we appear to our stockholders?" But in an AHC, this question must be revised to "What financial condition must we achieve to allow us to accomplish our mission?"

Academic Medical Centers↗
PubMed1999

Mild or moderate hypothermia but not increased oxygen breathing prolongs survival during lethal uncontrolled hemorrhagic shock in rats, with monitoring of visceral dysoxia.

OBJECTIVE: To test the hypotheses that during lethal uncontrolled hemorrhagic shock (UHS) in rats compared with normothermia and room air breathing: a) mild hypothermia would prolong survival time as well as moderate hypothermia; b) oxygen breathing would prolong survival further; and c) hypothermia and oxygen would mitigate visceral ischemia (dysoxia) during UHS. DESIGN: Prospective, randomized, controlled laboratory animal study. SETTING: Animal research facility. SUBJECTS: Male Sprague-Dawley rats. INTERVENTION: Fifty-four rats were lightly anesthetized with halothane during spontaneous breathing. UHS was induced by blood withdrawal of 3 mL/100 g over 15 mins, followed by 75% tail amputation with topical application of heparin. Five minutes after tail cut, rats were randomly divided into nine groups (6 rats each) with three rectal temperature levels (38 degrees C [100.4 degrees F; normothermia] vs. 34 degrees C [93.2 degrees F; mild hypothermia] vs. 30 degrees C [86 degrees F; moderate hypothermia]) by surface cooling; each with 3 FIO2 levels (0.25 vs. 0.5 vs. 1.0). Rats were observed without fluid resuscitation until death (apnea and pulselessness). Visceral ischemia was monitored by observing liver and gut surface PCO2. MEASUREMENTS AND MAIN RESULTS: Mean survival time, which was 51 mins in the control group with normothermia and FIO2 of 0.25, was more than doubled with hypothermia, to 119 mins in the combined mild hypothermia groups (p < .05) and to 132 mins in the combined moderate hypothermia groups (p < .05; NS for moderate vs. mild hypothermia). FIO2 had no statistically significant effect on survival time. Increases in visceral surface PCO2 correlated with hypotension (r2 = .22 for intestine and .40 for liver). Transiently, increased FIO2, not hypothermia, mitigated visceral ischemia. CONCLUSIONS: Both mild and moderate hypothermia prolonged survival time during untreated, lethal UHS in rats. Increased FIO2 had no effect on survival. The effects of hypothermia and increased FIO2 during UHS on viscera, the ability to be resuscitated, and outcome should be explored further.

Animals↗
PubMed1994

Relationships between 222Rn dissolved in ground water supplies and indoor 222Rn concentrations in some Colorado front range houses.

Indoor 222Rn concentrations were measured in 37 houses with alpha track detectors placed in water-use rooms near water sources (bathrooms, laundry rooms, and kitchens) and in non-water-use living rooms, dining rooms, and bedrooms away from water sources. Results show that relative contributions of 222Rn to indoor air from water use are insignificant when soil-gas concentrations are high but become increasingly important as the ratio of 222Rn-in-water: 222Rn-in-soil gas increases. High soil-gas 222Rn concentrations may mask 222Rn contributions from water even when waterborne 222Rn concentrations are as high as 750 kBq m-3. Ground water in Precambrian Pikes Peak granite averages 340 kBq m-3 222Rn, vs. 170 kBq m-3 in Precambrian migmatite, but average 222Rn concentrations in soil gas are also lower in migmatite. Because the ratio of 222Rn-in-water: 222Rn-in-soil gas may be consistently higher for houses in migmatite than in Pikes Peak granite, indoor air in houses built on migmatite may have a greater relative contribution from water use even though average 222Rn concentrations in the water are lower. Continuous monitoring of 222Rn concentrations in air on 15-min intervals also indicates that additions to indoor concentrations from water use are significant and measurable only when soil-gas concentrations are low and concentrations in water are high. When soil-gas concentrations were mitigated to less than 150 Bq m-3 in one house, water contributes 20-40% of the annual indoor 222Rn concentration in the laundry room (222Rn concentration in water of 670 kBq m-3). Conversely, when the mitigation system is inactive, diurnal fluctuations and other variations in the soil-gas 222Rn contribution swamp the variability due to water use in the house. Measurable variations in indoor concentrations from water use were not detected in one house despite a low soil-gas contribution of approximately 150 Bq m-3 because waterborne 222Rn concentrations also are low (80 kBq m-3). This result suggests that 222Rn concentrations in water near the recommended EPA limit in drinking water of 11 kBq m-3 may not contribute measurable amounts of 222Rn to indoor air in most houses.

Air Pollutants, Radioactive↗
PubMed1997

A comparison of independently conducted dose assessments to determine compliance and resettlement options for the people of Rongelap Atoll.

Rongelap Island was the home of Marshallese people numbering less than 120 in 1954; 67 were on the island and severely exposed to radioactive fallout from an atomic weapons test in March of that year. Those resident on Rongelap were evacuated 50 h after the test, returned 3 y later, then voluntarily left their home island in 1985 due to their ongoing fear of radiation exposure from residual radioactive contamination. Following international negotiations in 1991, a Memorandum of Understanding (MOU) was signed in early 1992 between the Republic of the Marshall Islands Government, the Rongelap Atoll Local Government, the U.S. Department of Energy, and the U.S. Department of the Interior. In this MOU it was agreed that the Republic of the Marshall Islands, with the aid of the U.S. Department of Energy, would carry out independent dose assessments for the purpose of assisting and advising the Rongelap community on radiological issues related to a safe resettlement of Rongelap. The MOU enacted two action levels which were agreed to be used to establish whether mitigation should be considered as a condition for resettlement of Rongelap Island: (1) no individual should receive an annual dose in the future of 1 mSv or more, above that from natural background radiation, assuming that his/her diet consists of only locally produced foods, and (2) the total surface soil concentration of plutonium and other transuranic elements must be less than 629 Bq kg(-1) (averaged over the top 5 cm). Environmental radiological data and dietary information were collected over two years (1992-1993) for the purpose of predicting future potential doses to Rongelapese who might resettle. In 1994, four independent assessments were reported, including one from each of the following entities: Marshall Islands Nationwide Radiological Study; Lawrence Livermore National Laboratory; an independent advisor from the United Kingdom (MCT); and a committee of the National Research Council. All four assessments concluded that possibly more than 25% of the adult population could exceed the 1 mSv y(-1) dose level based on strict utilization of a local food diet. The purpose of this report is to summarize the methodology, assumptions, and findings from each of four assessments; to summarize the recommendations related to mitigation and resettlement options; to discuss unique programmatic aspects of the study; and to consider the implications of the findings to the future of the Rongelap people.

Adult↗