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PubMed1986

A wide range of sensitivities to androgens develops in cloned Shionogi mouse mammary tumor cells.

Clones obtained in soft agar from a Shionogi mouse mammary carcinoma show marked heterogeneity of growth characteristics and sensitivities to androgens. These data pertain to spontaneous growth in the absence of androgens, maximal response to dihydrotestosterone (DHT) and Km values of the stimulatory action of DHT ranging from 0.008 to 10 ng/ml (1,250-fold range). Following 13 months in culture in the presence of 10 nM DHT, recloning of one original cell clone led to an even greater variation of androgen-free growth and of the maximal responses to DHT, while the Km values of DHT action ranged from 0.05 to 10 nM (200-fold range). The present demonstration of a marked heterogeneity of Km values of DHT action in subpopulations of tumors grown in a controlled environment has major implications for the efficient antihormonal treatment of androgen-sensitive diseases such as prostate cancer. Such data indicate that cell clones having a high degree of sensitivity to DHT (androgen-hypersensitive) can continue to grow in the presence of castration levels of androgens, thus suggesting that an antiandrogen is required in order to achieve a more complete androgen blockage and to induce a regression of these androgen-hypersensitive tumors.

Animals↗

PubMed2002

Using observed load distributions with a simple model to analyse the epidemiology of sea lice (Lepeophtheirus salmonis) on sea trout (Salmo trutta).

Sea lice are ectoparasites of salmonids that have been associated with the recent decline in sea trout numbers in north-west Europe. Observed patterns of louse load distribution between sea trout in the seas surrounding the UK, Ireland and Norway and a simple model have been used to analyse the epidemiology of lice. Loads are aggregated and deviate strongly from the Poisson distribution, although less than is observed with many other parasites. The louse numbers on fish from offshore sites are slightly less variable than for fish from coastal sites with comparable mean loads. Analysis of louse development stages and sexes shows that selection between hosts by sea lice plays a limited role. If host selection is absent, then associated poor condition would be caused by, not the cause of, high louse burdens; however the absence of such selection is not proved. Scenarios with infection that is patchy in space and time best generate the aggregated load patterns observed; these patches accord with observed swarms of copepodids. Prevalence patterns may indicate the movement of trout between environments. Control of copepodids in infection 'hot spots', either directly or through control of louse egg production in their catchment, may reduce louse loads on wild sea trout and, in particular, extreme and damaging loads.

Animals↗

PubMed2003

Wind tunnel studies on spray deposition on leaves of tree species used for windbreaks and exposure of honey bees.

A wind tunnel study was conducted to determine pesticide deposition on commonly used windbreak tree species used as spray drift barriers and associated exposure of honey bees. Although it has been known that windbreaks are effective in reducing chemical drift from agricultural applications, there is still an enormous information and data gap on details of the dependence of the mechanism on the biological materials of the barriers and on standardization of relevant assessment methods. Beneficial arthropods like honey bees are adversely affected by airborne drift of pesticides. A study was initiated by first establishing a wind tunnel to create a controlled environment for capture efficiency work. Suitable spray parameters were determined after a preliminary study to construct and develop a wind tunnel protocol. A tracer dye solution was sprayed onto the windbreak samples and honey bees located in the wind tunnel at various simulated wind speeds. Analysis of data from this work has shown that needle-like foliage of windbreak trees captures two to four times more spray than broad-leaves. In addition, it was determined that, at lower wind speeds, flying bees tend to capture slightly more spray than bees at rest.

Animals↗

PubMed2006

Optimum blood sampling time windows for parameter estimation in population pharmacokinetic experiments.

Clinical trials requiring the collection of pharmacokinetic information often specify blood samples to be taken at fixed times. This may be feasible when trial participants are in a controlled environment such as in early phase clinical trials, however it becomes problematic in trials where patients are in an out-patient clinic setting such as in late phase drug development. In such a situation it is common to take blood samples when it is convenient for all involved and may result in data that are uninformative. This paper proposes an approach to pharmacokinetic study design that allows greater flexibility as to when blood samples can be taken and still result in data that allows satisfactory parameter estimation. The sampling window approach proposed in this paper is based on determining time intervals around the D-optimum pharmacokinetic sampling times. These intervals are determined by allowing the sampling window design to result in a specified level of efficiency when compared to the fixed times D-optimum design. Several approaches are suggested for dealing with this design problem.

Blood Specimen Collection↗

PubMed1995

Biological mechanisms and perinatal exposure to abused drugs.

Use of illicit and licit drugs during pregnancy is a major public health concern, as it can have adverse effects on the developing fetus. Infants born of women addicted to narcotics, cocaine, alcohol, or polydrugs often undergo a characteristic withdrawal syndrome and may have physical, behavioral, and/or neurological abnormalities. As it is not feasible to ascertain whether these functional changes in human infants are produced by abused substance(s) per se or by a combination of complex socioeconomic factors and polydrug use, researchers in recent years have developed and utilized various innovative animal models to assess drug-induced alterations and their biological mechanisms during the developmental period under a controlled environment. To promote interdisciplinary communications as well as to assess the progress and the future needs in this area, the National Institute on Drug Abuse (NIDA) held a technical review at which biomedical researchers discussed their current findings in various physiological systems. This report summarizes the major findings and the methodological and experimental issues discussed at the conference. The meeting was held in Washington, DC, on May 25 and 26, 1994.

Animals↗

PubMed1995

Evaluation of the developmental toxicity of ethylene glycol aerosol in CD-1 mice by nose-only exposure.

Ethylene glycol (EG; CAS No. 107-21-1) is teratogenic to mice by whole-body (WB) exposure to aerosol (1000-2500 mg/m3). The WB results were confounded by possible exposure from ingestion after grooming and/or from percutaneous absorption. Therefore, CD-1 mice were exposed to EG aerosol (MMAD 2.6 +/- 1.7 microns) on Gestational Days (GD) 6 through 15, 6 hr/day, by nose-only (NO) (0, 500, 1000, or 2500 mg/m3) or WB exposures (0 or 2100 mg/m3, as positive control), 30/group. Five additional "satellite" females each at 2500 mg/m3 NO and 2100 mg/m3 WB were exposed on GD 6 for measurement of EG on fur. Control environments were water aerosol (4200 mg/m3 for NO; 2700 mg/m3 for WB). Females were weighed and evaluated for clinical signs and water consumption throughout gestation. On GD 18, maternal uterus, liver, and kidneys (2) were weighed, with kidneys examined microscopically. Corpora lutea and implantation sites were recorded. Live fetuses were weighed, sexed, and examined for structural alterations. For NO dams, kidney weights were increased at 1000 and 2500 mg/m3; no renal lesions and no other treatment-related maternal toxicity were observed. There were no effects on pre- or postimplantation loss; fetal body weights/litter were reduced at 2500 mg/m3. At 2500 mg/m3, incidences of fused ribs and skeletal variations were increased. The 2500 mg/m3 NO satellite animals had approximately 330 mg/kg extractable EG. The WB group exhibited maternal and developmental toxicity including increased fetal skeletal malformations and variations, confirming previous results, with 1390 mg/kg extractable EG on fur. Therefore, exposure of CD-1 mice to a respirable EG aerosol during organogenesis by NO inhalation resulted in minimal maternal toxicity at 1000 and 2500 mg/m3 and developmental toxicity at 2500 mg/m3. The NOAEL was 500 mg/m3 NO for maternal and 1000 mg/m3 NO for developmental toxicity. This study supports the interpretation of the initial EG WB results as due to systemic exposure from noninhalation routes since limiting noninhalation routes prevented almost all of the effects (including teratogenicity) observed in mice after WB exposure.

Abnormalities, Drug-Induced↗

PubMed2000

Appearance of a nocturnal peak of leptin secretion in the pubertal rat.

Whether leptin is involved in the timing of puberty remains highly controversial in the rat. Daytime leptin secretion shows little change during the transition into adulthood. Because leptin exhibits a diurnal variation in the adult, it is possible that the ontogeny of such a rhythm provides important information for the timing of puberty. To begin to evaluate this hypothesis, we determined the development of the diurnal leptin secretion in the rat. The young females were raised in a light-controlled environment (12L, 0700 h light on). A cannula was placed in the right atrium on the previous day, and blood samples were collected every 4 h on Days 21, 24, 28, 32, 36 (1 day after vaginal opening), and 48 (adult, diestrus of estrous cycle). In addition to vaginal opening, plasma prolactin levels were determined as an endocrine index of puberty. Changes in food intake were monitored because nocturnal food intake has been considered to be a synchronizer for the leptin rhythm. This pattern of food intake was clearly evident throughout the ages studied. By contrast, there was no leptin rhythm at 21 and 24 days of age. Beginning at 28 days, leptin secretion exhibited a significant nocturnal peak (2300 h); this nocturnal peak increased in amplitude at 32 and 36 days and was still apparent in the cycling adult at Day 48. Plasma prolactin did not exhibit a diurnal rhythm but it increased from Days 32 to 48. The present findings indicate that in the rat, both the appearance of the nocturnal leptin rhythm and the nocturnal increase in circulating leptin levels during development carry information for timing the onset of puberty.

Aging↗

PubMed2000

Adolescent participation in the U.K. national lottery games.

This study investigated illegal participation in the two U.K. National Lottery games (on-line game and scratchcards) by children under the age of 16 years. The sample consisted of 256 children aged between 13 and 15 years from four mixed-sex comprehensive schools/colleges, which serve city, town, rural and coastal catchment areas in the county of Devon, U.K. Pupils completed a questionnaire in a controlled environment at their respective schools/colleges. The findings indicated that 56% of the sample had participated in the National Lottery on-line game and 54% in the National Lottery Instants scratchcards. Regression analysis revealed that the best predictors of participation in the on-line game were income, household participation, whether the TV show was watched and whether a retailer had ever refused to sell a child a lottery ticket. The same variables (minus watching of the TV show) were also the best predictors of buying scratchcards.

Adolescent↗

PubMed2002

Modeling nucleation and coagulation modes in the formation of particulate matter inside a turbulent exhaust plume of a diesel engine.

This paper presents the results from a study that is aimed at predicting the nucleation, coagulation, and dynamics of particulate matter (PM) emissions from on-road heavy-duty diesel vehicles. The PM concentration is predicted from the composition of fuel, and operating and ambient conditions. A numerical algorithm for simultaneously solving the coagulation, condensation, and nucleation equations is developed. The effect of relative humidity on the nucleation rate and the nucleus size is also discussed. In addition, the effect of the ambient air dilution on PM size distribution is numerically predicted for a diesel-powered truck operating in a controlled environment at NASA Langley wind-tunnel facility. The particle size distribution and concentration are measured at four different locations in a turbulent plume from the diesel exhaust in the tunnel, and an excellent agreement between the measured and predicted PM concentration values at these locations inside the tunnel is observed.

Journal Article↗

PubMed1998

Effect of Soil Texture and Soil Sterilization on Susceptibility of Ovipositing Grasshoppers to Beauveria bassiana

The effect of conidial concentration, soil texture, and soil sterilization on the efficacy of Beauveria bassiana against ovipositing grasshoppers (Melanoplus sanguinipes) was investigated in a controlled environment. In the first experiment, mortality of female grasshoppers ovipositing into a sterile loamy-sand soil containing conidia of B. bassiana was measured. The prevalence of mortality increased as the concentration of conidia in soil increased, and a median lethal concentration of 10(4) colony-forming units (CFU) per gram of soil (dry weight) was observed. Conidia (10(2.9) to 10(3) CFU per abdomen) were recovered from the abdomens of grasshoppers ovipositing into sand containing 10(5.5) and 10(6) conidia per gram. Similar numbers of eggs were laid among treatments during the first oviposition period (1 to 7 days), but an effect of conidial concentration on eggs laid was observed during the second oviposition period (8 to 14 days). This was attributed to reduction in female numbers and not to reduction in fecundity independent of mortality. In a second experiment, grasshoppers oviposited into soils of three different textures (loamy-sand, sandy-loam, or clay-loam) that were amended with 10(5) B. bassiana conidia per gram and possessed either a viable or heat-killed microflora. There was no effect of soil texture on mortality of ovipositing grasshoppers, on the number of eggs laid, on positioning of egg pods in the soil profile, or on numbers of B. bassiana CFU recovered from female abdomens. However, a higher prevalence of mortality was observed for females ovipositing into the sterilized than nonsterilized sandy-loam and clay-loam soils. Substantial populations of fungi and bacteria were recovered from nonsterilized soils. The predominant fungi isolated from these soils were members of the genera Chrysosporium, Fusarium, Gliocladium, Penicillium, Rhizopus, and Trichoderma, whereas Bacillus, Paenibacillus, and Pseudomonas species were the most commonly isolated bacteria. This study demonstrates that ovipositing grasshoppers are susceptible to relatively low densities of conidia in soils of varying textures, but the soil microflora may have an adverse affect on the efficacy of B. bassiana in field soils. Copyright 1998 Academic Press. Copyright 1998 Academic Press

Journal Article↗

PubMed1994

Determination of electrostatic potential around specific locations on the surface of actin by diffusion-enhanced fluorescence resonance energy transfer.

In this study we have established systematic procedures for the measurement of electrostatic potentials around specific and localized portions of protein surfaces. Diffusion-enhanced fluorescence energy transfer was used for these determinations. Energy transfer from donor molecules to freely diffusing acceptors is sensitive to the electrostatic potential around the donor when the acceptors possess electric charges. To quantify this sensitivity phenomenon in a controllable environment, we observed energy transfer from excited terbium chelate donors of known electric charge to a series of acceptors of different charges but bearing the same chromophore group. The rate of energy transfer was calculated theoretically (considering the structural arrangement of charged groups around the chromophore center), as well as determined experimentally (by time-resolved detection of terbium luminescence), with the two values obtained by the different means in close agreement. Having established the validity of this procedure using a relatively simple system, we studied the electrostatic conditions around two specific sites on the surface of actin molecules. A negative potential was found at both sites; the potential at one location (around the myosin binding site) was nearly neutralized by the addition of myosin subfragment-1, while the potential at the other site (around the phalloidin binding site) was not significantly affected.

Actins↗

PubMed1993

Fluorescence ratio imaging measurement of pH gradients: calibration and application in normal and tumor tissues.

The fluorescence ratio imaging technique is currently applied in vitro and in vivo to measure intracellular as well as extracellular pH. To date, however, no effort has been made to assess the technique's ability to detect spatial pH gradients in vitro or in vivo, where pH gradients are known to exist, in a controlled environment using an independent pH measurement system. We present here both in vitro calibration and in vivo application of fluorescence ratio imaging to measure pH gradients in a biologically useful pH range (6.2-7.8). Isoelectric focusing in short polyacrylamide gels was used to establish spatial pH gradients ranging from approximately 0.2 to 0.5 pH units/mm. The pH gradients were measured independently with fluorescence ratio imaging microscopy (FRIM) and a surface electrode. The average difference between measurements using the two techniques was 0.043 pH units for 10-mm polyacrylamide gels (100 measurements in 12 gels) and 0.046 pH units for 20-mm gels (114 measurements in 15 gels). These gel studies have demonstrated the use of isoelectric focusing to calibrate FRIM for measuring spatial pH gradients characteristic of those found in tumors in vivo. The feasibility of FRIM was tested in vivo by measuring pH in a solid tumor (VX2 carcinoma) and surrounding normal granulation tissue grown in the rabbit ear chamber. The average (+/- SD) pH of normal and neoplastic regions of the composite tissue was 7.18 +/- 0.11 (n = 158) and 6.75 +/- 0.10 (n = 191), respectively. The pH varied by an average of approximately 0.6 pH units over the 5-mm diameter of the chamber and showed a sharp difference at the interface of the two tissue types. These pH values are consistent with the current pH data on normal and neoplastic tissues. Thus FRIM should permit noninvasive in vivo evaluation of new pH-modifying agents and, in combination with other optical techniques, should offer novel mechanistic information about tumor pathophysiology.

Animals↗

PubMed1996

Chemical sensitivities and the Gulf War: Department of Veterans Affairs Research Center in basic and clinical science studies of environmental hazards.

The purpose of the New Jersey Center for Environmental Hazards Research is to define the illness referred to as Persian Gulf Syndrome (PGS). Our preliminary data indicated that more than half of the Persian Gulf Registry (PGR) veterans reported illness characterized by severe fatigue and symptoms consistent with chemical sensitivities. Therefore, our research approach focuses on investigations of veterans with chronic fatigue syndrome (CFS) and multiple chemical sensitivities (MCS). Project 1 is an epidemiological study of 2800 PGR veterans. Symptoms, indices of Chronic Fatigue (CF) and Chemical Sensitivity (CS), and risk factors will be surveyed with mailed questionnaires. Risk factors include demographics, past medical history, psychosocial variables, Gulf War experiences such as prophylactic medication use, occupational and environmental exposures, and pesticide exposures. Symptoms will be clustered to define Gulf War Syndromes. Significant associations between risk factors and these symptom clusters will also be investigated Subjects identified as CF, CS, or both will be recruited into Projects 2 and 3. In Project 2, healthy veterans will be compared to veterans with CF, CS, and CF concurrent with CS. Veterans will undergo four studies: (1) viral-immunological, (2) psychiatric, psychological, behavioral, and neuropsychological, (3) autonomic dysregulation, and (4) marker of P4501A2 induction resulting from exposure to combusting material. The purpose of Project 3 is to test the autonomic, immunologic, neuropsychologic, and psychologic responses of veterans with CS or CF to two stressors: controlled chemical exposure and exercise. CS subjects will undergo chemical exposures in our Controlled Environment Facility (CEF) to assess their biologic and psychologic response to low-level exposure. CF subjects will undergo a maximal treadmill exercise test. Circadian patterns of catecholamines and axillary temperature, viral burden, and cardiovascular and endocrine reactivity will be measured in response to this physical stressor. Project 4 is an animal study evaluating the interaction between stress and pathology/physiology when rats are predisposed to disease by exposure to Soman or to Dioxin. Two strains of rats that differ in stress reactivity will be used to determine the interaction of hereditary factors and chemical exposure.

Comorbidity↗

PubMed1995

Expression of Arabidopsis cytosolic ascorbate peroxidase gene in response to ozone or sulfur dioxide.

The effects of ozone or sulfur dioxide on antioxidant enzymes were investigated in Arabidopsis thaliana. Plants were fumigated with 0.1-0.15 ppm ozone or sulfur dioxide up to about 1 week in an environment-controlled chamber. Both pollutants increased the activities of ascorbate peroxidase and guaiacol peroxidase in leaves, but had little effect on the activities of superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase or glutathione reductase. Ozone was more effective than sulfur dioxide in increasing the activities of the peroxidases. Ascorbate peroxidase activity increased 1.8-fold without a lag period during fumigation with 0.1 ppm ozone, while guaiacol peroxidase activity increased 4.4-fold with a 1-day lag. Expression of the APX1 gene encoding cytosolic ascorbate peroxidase was further investigated. Its protein levels in leaves exposed to 0.1 ppm ozone for 4 or 8 days were 1.5-fold higher than in controls. Both ozone and sulfur dioxide elevated APX1 mRNA levels in leaves at 4 and 7 days, whereas at 1 day only ozone was effective. The induction of APX1 mRNA levels by ozone (3.4- to 4.1-fold) was more prominent than that by sulfur dioxide (1.6- to 2.6-fold). The APX1 mRNA level increased by day and decreased by night. Exposure of plants to 0.1 ppm ozone enhanced the APX1 mRNA level within 3 h, which showed a diurnal rhythm similar to that of the control. These results demonstrate that near-ambient concentrations of ozone as well as similar concentrations of sulfur dioxide can induce APX1 gene expression in A. thaliana.

Air Pollutants↗

PubMed1994

Expression of sunflower low-molecular-weight heat-shock proteins during embryogenesis and persistence after germination: localization and possible functional implications.

We isolated and sequenced Ha hsp17.9, a DNA complementary (cDNA) of dry-seed stored mRNA that encodes a low-molecular-weight heat-shock protein (LMW HSP). Sequence analysis identified Ha hsp17.9, and the previously reported Ha hsp17.6, as cDNAs encoding proteins (HSP17.6 and HSP17.9) which belong to different families of cytoplasmic LMW HSPs. Using specific antibodies we observed differential expression of both proteins during zygotic embryogenesis under controlled environment, and a remarkable persistence of these LMW HSPs during germination. Immuno-blot analysis of HSP17.9 proteins in two-dimensional gels revealed that the polypeptides expressed in embryos were indistinguishable from LMW HSPs expressed in vegetative tissues in response to water deficit; but they appeared different from homologous proteins expressed in response to thermal-stress. Tissue-print immunolocalization experiments showed that HSP17.9 and HSP17.6 were homogeneously distributed in every tissue of desiccation-tolerant dry seeds and young seedlings under non-stress conditions. These results demonstrate developmental regulation of specific, cytoplasmic, plant LMW HSPs, suggesting also their involvement in water-stress tolerance.

Adaptation, Biological↗

PubMed1987

Human foetal kidney explants in serum-free organ culture.

The purpose of the work was to develop an in vitro model for the study of human kidney development. Human metanephric explants from foetuses 10-18 weeks of gestational age were cultured in serum-free Leibovitz L-15 medium without hormones. Under the current minimal conditions for growth, the system permitted to maintain the renal tissues in culture for periods up to 9 days, although no evident sign of morphological differentiation was observed. However, during the studied period the overall architecture of the explants was preserved as well as the ultrastructural features of cytoplasmic organelles. The incorporation of 3H-thymidine and 3H-leucine indicated that DNA and protein synthesis was maintained or increased. Glycoprotein synthesis evaluated by 3H-glucosamine incorporation and radioautography continued in mesangium as well as in glomerular and tubular basement membranes. Alkaline phosphatase, gamma-glutamyltranspeptidase (brush border) and catalase (peroxisomes) activities remained histochemically active. The proposed organ culture system appears as a reliable and promising model that will provide basic data on the morphology and functional characteristics of the developing kidney. Since it is achieved in a completely controlled environment, it will permit to study the role of growth factors and hormones in proliferation and differentiation of the cell populations during development of the human foetal kidney.

Alkaline Phosphatase↗

PubMedDate not supplied

Nonoperative management of esophageal perforation secondary to balloon dilatation.

Esophageal perforation is usually considered a surgical emergency. However, esophageal perforation after therapeutic endoscopic manipulation is a different entity. This type of perforation occurs in a controlled environment and the perforation is usually detected early. Three documented cases of perforation during endoscopic balloon dilatation are described. They were successfully treated nonoperatively.

Aged↗

PubMed1996

Regional differences in age-related decrements of the cutaneous vascular and sweating responses to passive heating.

Ten older (aged 64-76 years) and ten younger (aged 20-24 years) healthy men were exposed to a standard heat stress [by placing the lower legs and feet in a water bath at 42 degrees C while sitting in a controlled environment (ambient temperature 35 degrees C and 45% relative humidity) for 60 min]. During passive heating, the rectal temperature of the older men was significantly greater (P < 0.05) and mean skin temperature was lower (P < 0.001), compared to the younger men. Skin blood flow by laser Doppler flowmetry (LDF) was significantly lower on the chest and thigh for the older men (P < 0.001), but forehead LDF did not differ between the groups. The percentages of total LDF in the older men to total LDF in the younger men for the last 30 min were 99%, 58% and 50% on the forehead, chest and thigh, respectively. The age-related differences in LDF responses mirrored cutaneous vascular conductances (CVC), since no group and time effects were observed in mean arterial blood pressure during the test. During the last 30 min the local sweat rates (msw) on the back and thigh were significantly lower for the older men (P < 0.02), but not on forehead, chest and forearm, although the older men had lower msw during the first 30 min exposure regardless of site (P < 0.03). The percentages of total msw in the older men to total msw in the younger men during the last 30 min were 105%, 99%, 63%, 106% and 88% on the forehead, chest, thigh, forearm, and back, respectively. During the latter half of the exposure, the older men had similar LDF, CVC and msw on the forehead, lower LDF and CVC and a similar msw on the chest, and lower LDF, CVC and msw on the thigh, compared to the younger men. These results suggest firstly that regional differences exist in the age-related decrement of cutaneous vasodilatation as well as sweat gland function, secondly that the age-related decrement in cutaneous vascular function may precede a decrement in sweat gland function, and thirdly that the successive decrements may develop sequentially from the lower limbs to the upper body, and head.

Adult↗