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PubMed1997

Effects of bioreactor retention time on aerobic microbial decomposition of CELSS crop residues.

The focus of resource recovery research at the KSC-CELSS Breadboard Project has been the evaluation of microbiologically mediated biodegradation of crop residues by manipulation of bioreactor process and environmental variables. We will present results from over 3 years of studies that used laboratory- and breadboard-scale (8 and 120 L working volumes, respectively) aerobic, fed-batch, continuous stirred tank reactors (CSTR) for recovery of carbon and minerals from breadboard grown wheat and white potato residues. The paper will focus on the effects of a key process variable--bioreactor retention time--on response variables indicative of bioreactor performance. The goal is to determine the shortest retention time that is feasible for processing CELSS crop residues, thereby reducing bioreactor volume and weight requirements. Pushing the lower limits of bioreactor retention times will provide useful data for engineers who need to compare biological and physicochemical components. Bioreactor retention times were manipulated to range between 0.25 and 48 days. Results indicate that increases in retention time lead to a 4-fold increase in crop residue biodegradation, as measured by both dry weight losses and CO2 production. A similar overall trend was also observed for crop residue fiber (cellulose and hemicellulose), with a noticeable jump in cellulose degradation between the 5.3 day and 10.7 day retention times. Water-soluble organic compounds (measured as soluble TOC) were appreciably reduced by more than 4-fold at all retention times tested. Results from a study of even shorter retention times (down to 0.25 days), in progress, will also be presented.

Aerobiosis↗

PubMed2001

Effects of genotype, nutrient availability, and defoliation on aspen phytochemistry and insect performance.

Genetic and environmental variability, and their interactions, influence phytochemical composition and, in turn, herbivore performance. We evaluated the independent and interactive effects of plant genotype, nutrient availability, and defoliation on the foliar chemistry of quaking aspen (Populus tremuloides) and consequences for performance of gypsy moths (Lymantria dispar). Saplings of four genotypes were grown under two conditions of nutrient availability and subjected to three levels of artificial defoliation. Concentrations of all secondary and primary metabolites evaluated responded to at least one or more of the experimental treatments. Of the secondary metabolites, phenolic glycosides were affected strongly by genotype, less so by nutrient availability, and not induced by defoliation. Condensed tannins were strongly dependent upon genotype, soil nutrient availability, and their interaction, and, in contrast to phenolic glycosides, were induced by artificial defoliation. Of the primary metabolites, foliar nitrogen was affected by genotype and soil nutrient availability. Starch concentrations were affected by genotype, nutrient availability, defoliation and interactions among these factors. Foliar water content responded to genotype, nutrient availability, and defoliation, and the effect of nutrient availability depended on genotype. Herbivore performance on these plants was strongly influenced by plant genotype and soil nutrient availability, but much less so by defoliation. Although several of the compound types (condensed tannins, starch, and water) responded to defoliation, quantitative variation in these compounds did not contribute to substantive changes in herbivore performance. Rather, the primary source of variation in insect performance was due to plant genotype (phenolic glycoside levels), while nutrient availability (foliar nitrogen levels) was of secondary importance. These results suggest that genetic variation in aspen plays a major role in determining patterns of insect performance, whereas environmental variation, such as was tested, here is of negligible importance.

Animals↗

PubMed1998

Modeling disease incidence rates in families.

We apply an extended Cox model to study latent genes and measured environmental exposures simultaneously as risk factors for disease. Using this method, we assume Mendelian transmission of the genes and either dominant or recessive gene action. We compared the results from this model with those obtained under a model that includes the environmental variables and a family risk score. We demonstrate the method in samples of 1,433 Caucasian families (N = 6,791) and 206 African-American families (N = 771) from the National Heart, Lung, and Blood Institute Family Heart Study. In Caucasians, we found evidence suggesting that having ever smoked increased the risk of coronary heart disease only in individuals who carry a genetic susceptibility. We also noted that in both Caucasian and African-American families, the relative risk of coronary heart disease for ever-treated vs never-treated for high serum total cholesterol increased after including an unobserved susceptibility genotype in the model. This finding implied that there may be genes influencing coronary heart disease independent of those that influence total cholesterol. Such findings were not evident when genetic risk was summarized by the family history score. We also discuss the extension of the model to address the etiology of complex diseases.

Age of Onset↗

PubMed1998

[Study of skin temperature, microclimate and comfort of clothing of old females at rest--ambient temperature x humidity: 30 degrees C. R.H.80%, 30 degrees C. R.H.45%, 20 degrees C. R.H.45%].

Old females are compared to young females for the purpose of studying the difference in comfort caused by the environmental variables of temperature and humidity as well as the form of clothing. Eight experiments were performed in three settings: (a) 30 degrees C R.H.80%; 30 degrees C R.H.45%; and 20 degrees C R.H.45%. The ages of the subjects range from 62 to 68 (Mean = 65.17, S.D. = 1.68) among old females and from 20 to 23 (Mean = 20.83, S.D. = 0.76) among young females. The following results were obtained: (1) The young females were sensitive to hot temperatures, while the old females were not. On the other hand, the old females were more sensitive to cold temperatures, under 20 degrees C R.H.45%, than the young females. In temperatures under 30 degrees C R.H.80%, the heat radiation from the young females was higher than that of the old females. Under 20 degrees C R.H.45%, the heat radiation from the old females was higher than from the young females. The old females are thought to decline in physiogenic function due to enduring both hot and cold temperatures. (2) The correlation between the temperature in clothes and comfort among the old females is not different from the same correlation among the young females. This conclusion agrees with previously published studies of the young females. (3) Skin temperature and bloodstream are measured, according to clothing form. As a result, a long skirt is the highest in thermal insulation, long pants the next highest, and a short skirt is the lowest. (4) The effect of thermal insulation provided by a lap robe was tested in both groups. The lap robe was found to be more effective for the older group than the younger in temperatures under 20 degrees C R.H.45%. Hence, the role of clothes in offsetting for the decline in the thermoregulation function that compensates for environmental change is more important for old females than for young.

Aged↗

PubMed1997

Cat allergen (Fel d 1) levels on school children's clothing and in primary school classrooms in Wellington, New Zealand.

BACKGROUND: New Zealand has a high prevalence of the major allergic diseases including asthma, rhinitis, and eczema, and cat ownership is common, with more than 50% of homes containing a cat. OBJECTIVE: The study was designed to examine the levels of cat allergen (Fel d 1) in the primary school environment, both on floors and on children's clothing. METHODS: We collected and analyzed dust samples from 11 school classrooms and from 202 children's garments using vacuum sampling and two-site monoclonal antibody ELISA, respectively. Environmental variables were identified by questionnaire. RESULTS: The geometric mean level of Fel d 1 in classrooms was 2.61 micro/gm (95% confidence interval, 1.28 to 3.84); however, seven classrooms had a floor sample with Fel d 1 greater than 8 microg/m2. Carpeted floor levels at 2.21 microg/gm (1.28 to 3.84) were considerably higher than those on uncarpeted floors, at 0.33 microg/gm (0.1 to 1.14). Floor levels and pupil cat ownership rates were positively correlated (r2 = 0.93, p = 0.0003). Children from homes with cats carried allergen on their clothes (mean Fel d 1, 6.10 microg per garment compared with non-cat owners (0.72 microg per garment). Wool and polyester garments contained more Fel d 1 than cotton clothing. Girls' clothing had significantly higher levels of allergen than did that of boys, even after controlling for cat status and fabric differences. CONCLUSIONS: Carpeting should be discouraged in environments such as schools and child care centers, where children spend considerable time. Transport of Fel d 1 on clothing from the domestic to the school environment is a major source of classroom cat allergen.

Adult↗

PubMed2006

Ecosystem responses to extreme natural events: impacts of three sequential hurricanes in fall 1999 on sediment quality and condition of benthic fauna in the Neuse River Estuary, North Carolina.

A study was conducted in November 1999 to assess sediment quality and condition of benthic fauna in the Neuse River Estuary (NRE), North Carolina, USA, following the passage of three Atlantic hurricanes during the two months prior. Samples for analysis of macroinfauna (>0.5 mm sieve size), chemical contamination of sediments, and other abiotic environmental variables (salinity, dissolved oxygen, pH, depth, sediment granulometry) were collected at 20 sites from the mouth of the Neuse River at Pamlico Sound to approximately 90 km upstream. Results were compared to those obtained from the same area in July 1998 using similar protocols. Depressed salinity, caused by extreme rainfall and associated high freshwater flow, persisted throughout much of the estuary, which had experienced periods of water-column stratification and hypoxia of underlying waters. Fifteen of the 20 sites, representing 299 km2 (76% of the survey area), also showed signs of benthic stress based on a multi-metric benthic index of biotic integrity (B-IBI). Benthic impacts included reductions in the abundance, diversity, and numbers of species and shifts in taxonomic composition, with a notable increase in dominance of the opportunistic polychaete Mediomastus ambiseta as other former dominant species declined. There was no significant increase in the extent of chemical contamination compared to pre-hurricane conditions. Storm-related reductions in dissolved oxygen and salinity were the more likely causes of the observed benthic impacts, though it was not possible, based on these results, to separate storm effects from seasonal changes in the benthos and annual episodes of summer anoxia and hypoxia.

Disasters↗

PubMed1994

Comparative efficacy of sunscreen reapplication regimens in children exposed to ambient sunlight.

Undercompliance with sunscreen reapplication recommendations is a probable factor in suboptimal childhood ultraviolet radiation (UVR) protection. However, improving on the ability of sunscreens to absorb UVR without requiring frequent reapplication is difficult because the models most frequently used to develop and evaluate photoprotectants have only a limited ability to incorporate behavioral and environmental variables that are primarily responsible for loss of sunscreen efficacy. Hence, the objective of the present work was to develop a method to evaluate the efficacy of various regimens of sunscreen reapplication in children, under conditions of unrestricted behavior and exposure to ambient sunlight. Ninety-eight children, ages 7-12, Fitzpatrick skin types I-III, were divided between two study groups. The majority were types I-II, and all types were approximately equally represented between the groups. The children received single or multiple applications of a sun protection factor 25 sunscreen to preassigned lateral halves of the body and engaged in unrestricted activities throughout a 6- (group I) or 8-h (group II) period of sun exposure at a seaside location. The end measurement for these studies was incidence and severity of erythema 18 to 22 h after peak UV exposure. The results obtained showed that 1 or 4 sunscreen applications yielded comparable erythema protection after a 6-hour sun exposure, totaling 13 minimal erythema doses (MED). However, after an 8-h, 21 MED exposure, incidence and severity of erythema was greater at body sites treated with 1 compared with 5 sunscreen applications.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylates↗

PubMed1990

Organic and inorganic components in estuarine colloids: implications for sorption and transport of pollutants.

In colloids isolated from Chesapeake Bay and its subestuaries the concentrations of Al, Fe, and a number of trace elements were determined to vary with the clay mineral fraction that was most abundant in freshwater samples collected during the winter. The elements As, Ba, Sb, and Zn, however, increased with increasing organic content, indicating a covariance with the organic component. Organic analyses for amino acids (proteins), carbohydrates, and lipids indicate that these biopolymers comprised 4 to 22%, 20 to 60%, and less than 1%, respectively, of the colloidal organic carbon in these samples. The results are significant because amino acids and carbohydrates contain oxygen, nitrogen, and sulfur functional groups capable of reacting with trace metals and organic pollutants. The sorption properties of several neutral hydrophobic organic compounds, including PAHs and herbicides, and several aromatic amines were investigated using the estuarine colloidal material. The effects of several environmental variables on these sorption properties were determined. The results indicate that colloids have the capacity to sorb and transport relatively insoluble pollutants that otherwise might remain immobile in the environment. Colloidal organic matter in natural water systems (lakes, rivers, estuaries and the oceans, as well as groundwater) may serve as substrates for the sorption or binding of organic contaminants. Although most of the data has been developed using neutral hydrophobic organic compounds, data also exist for selected polar compound groups such as aromatic amines. The chemical behavior of these compound groups in interaction with DOM appears to have some similarity to their chemical interaction with sediments and soils. Partitioning constants are linear, except for polar compounds, and appear to be closely correlated to fundamental compound properties such as solubilities and octanol-water partition coefficients. Even though a variety of methods were used to collect the colloids for study and to determine partition coefficients, no single method appears to be superior. Ultrafiltration techniques appear to be optimal for collecting the colloids, since this method subjects the materials to less extreme chemical conditions than the preparation of humic extracts, whereas equilibrium techniques such as dialysis and head space analysis appear to yield the best results for partitioning constants. However, each of these techniques has limitations with respect to the classes of compounds that can be studied successfully.

Colloids↗

PubMedDate not supplied

Environmental regulation of xylem sap flow and total conductance of Larix gmelinii trees in eastern Siberia.

Xylem sap flow and environmental variables were measured on seven consecutive midsummer days in a 130-year-old Larix gmelinii (Rupr.) Rupr. forest located 160 km south of Yakutsk in eastern Siberia, Russia (61 degrees N, 128 degrees E, 300 m asl). The site received 20 mm of rainfall during the 4 days before measurements, and soil samples indicated that the trees were well watered. The tree canopy was sparse with a one-sided leaf area index of 1.5 and a tree density of 1760 ha(-1). On a clear day when air temperature ranged from 9 to 29 degrees C, and maximum air saturation deficit was 3.4 kPa, daily xylem sap flux (F) among 13 trees varied by an order of magnitude from 7 l day(-1) for subcanopy trees (representing 55% of trees in the forest) to 67 l day(-1) for emergent trees (representing 18% of trees in the forest). However, when based on xylem sap flux density (F'), calculated by dividing F by projected tree crown area (a surrogate for the occupied ground area), there was only a fourfold range in variability among the 13 trees, from 1.0 to 4.4 mm day(-1). The calculation of F' also eliminated systematic and large differences in F among emergent, canopy and subcanopy trees. Stand-level F', estimated by combining half-hourly linear relationships between F and stem cross-sectional area with tree size distribution data, ranged between 1.8 +/- 0.4 (standard deviation) and 2.3 +/- 0.6 mm day(-1). These stand-level F' values are about 0.6-0.7 mm day(-1) (30%) larger than daily tree canopy transpiration rates calculated from forest energy balance and understory evaporation measurements. Maximum total tree conductance for water vapor transfer (G(tmax), including canopy and aerodynamic conductances), calculated from the ratio of F' and the above-canopy air saturation deficit (D) for the eight trees with continuous data sets, was 9.9 +/- 2.8 mm s(-1). This is equivalent to a leaf-scale maximum stomatal conductance (g(smax)) of 6.1 mm s(-1), when expressed on a one-sided leaf area basis, which is comparable to the published porometer data for Larix. Diurnal variation in total tree conductance (G(t)) was related to changes in the above-canopy visible irradiance (Q) and D. A saturating upper-boundary function for the relationship between G(t) and Q was defined as G(t) = G(tmax)(Q/[Q + Q(50)]), where Q(50) = 164 +/- 85 micro mol m(-2) s(-1) when G(t) = G(tmax)/2. Accounting for Q by excluding data for Q < Q(85) when G(t) was at least 85% of G(tmax), the upper limit for the relationship between G(t) and D was determined based on the function G(t) = (a + blnD)(2), where a and b are regression coefficients. The relationship between G(t) and D was curvilinear, indicating that there was a proportional decrease in G(t) with increasing D such that F was relatively constant throughout much of the day, even when D ranged between about 2 and 4 kPa, which may be interpreted as an adaption of the species to its continental climate. However, at given values of Q and D, G(t) was generally higher in the morning than in the afternoon. The additional environmental constraints on G(t) imposed by leaf nitrogen nutrition and afternoon water stress are discussed.

Journal Article↗

PubMed2004

Flaked stones and old bones: biological and cultural evolution at the dawn of technology.

The appearance of Oldowan sites ca. 2.6 million years ago (Ma) may reflect one of the most important adaptive shifts in human evolution. Stone artifact manufacture, large mammal butchery, and novel transport and discard behaviors led to the accumulation of the first recognized archaeological debris. The appearance of the Oldowan sites coincides with generally cooler, drier, and more variable climatic conditions across Africa, probably resulting in a net decrease in woodland foods and an increase in large mammal biomass compared to the early and middle Pliocene. Shifts in plant food resource availability may have provided the stimulus for incorporating new foods into the diet, including meat from scavenged carcasses butchered with stone tools. Oldowan artifact form varies with clast size, shape, raw material physical properties, and flaking intensity. Oldowan hominins preferred hard raw materials with good fracture characteristics. Habitual stone transport is evident from technological analysis, and raw material sourcing to date suggests that stone was rarely moved more than 2-3 km from source. Oldowan debris accumulation was spatially redundant, reflecting recurrent visitation of attractive points on the landscape. Thin archaeological horizons from Bed I Olduvai Gorge, Tanzania, were probably formed and buried in less than 10 years and document hominin processing of multiple carcasses per year. Transport beyond simple refuging behavior is suggested by faunal density at some site levels. By 2.0 Ma, hominin rank within the predatory guild may have been moderately high, as they probably accessed meaty carcasses through hunting and confrontational scavenging, and hominin-carnivore competition appears minimal at some sites. It is likely that both Homo habilis sensu stricto and early African H. erectus made Oldowan tools. H. habilis sensu stricto was more encephalized than Australopithecus and may foreshadow H. erectus in lower limb elongation and some thermoregulatory adaptations to hot, dry climatic conditions. H. erectus was large and wide-ranging, had a high total energy expenditure, and required a high-quality diet. Reconstruction of H. erectus reproductive energetics and socioeconomic organization suggests that reproductively active females received assistance from other group members. This inference, combined with archaeological evidence for acquisition of meaty carcasses, suggests that meat would have been a shared food. This is indirectly confirmed by nutritional analysis suggesting that the combination of meat and nutritionally dense plant foods was the likely diet fueling body size increase and encephelization in Homo. Most discussion of Oldowan hominin behavior and ecology, including that presented here, is based on materials from a few sites. There is a critical need to analyze additional large, primary-context lithic and faunal assemblages to better assess temporal, geographic, and environmental variability in Oldowan behavior.

Adaptation, Physiological↗

PubMed2026

ALPHA-1 antitrypsin genotype, sex, and lung cancer: Clinical and molecular characterisation.

INTRODUCTION AND OBJECTIVES: Alpha-1 antitrypsin deficiency is associated with lung and liver disease, but its role in lung carcinogenesis remains unclear. This study aimed to compare the clinical, functional, and molecular characteristics of lung cancer according to alpha-1 antitrypsin (AAT) genotype and, additionally, to explore differences by sex and the possible influence of environmental exposures. PATIENTS AND METHODS: We conducted a cross-sectional, single-centre study including 407 patients with incident lung cancer diagnosed between 2020 and 2023. Clinical, functional, radiological, molecular, and environmental variables were collected. Comparisons were performed between carriers and non-carriers of altered AAT alleles and between women and men. RESULTS: Of the 394 patients with available genotyping, 24.4% carried at least one altered allele. No significant differences were observed by genotype in smoking status, radon exposure, comorbidities, lung function, or histological subtype. Carriers showed significantly lower serum AAT levels and a higher frequency of values < 116 mg/dL (p < 0.001). PD-L1 expression ≥ 50% was more common in carriers (28.1% vs. 19.4%; p = 0.036). In the multivariable analysis, the altered AAT genotype remained independently associated with a higher probability of PD-L1 expression ≥ 50% (aOR = 2.04; 95% CI: 1.09-3.80; p = 0.026). Women had lower cumulative tobacco exposure, lower prevalence of emphysema and COPD, greater biomass exposure, higher frequency of adenocarcinoma, and more EGFR mutations (p < 0.001). CONCLUSIONS: Patients carrying altered AAT alleles did not exhibit a distinctly different clinical profile, although they showed higher PD-L1 expression (≥50%). Furthermore, significant differences were observed between women and men in terms of exposure, histology and molecular alterations.

Humans↗

PubMed2006

Bacterial contamination associated with estuarine shoreline development.

AIMS: To examine the relationships among increasing estuarine shellfish closings due to bacterial contamination, adjacent shoreline land uses and environmental variables. METHODS AND RESULTS: A 1 year study of faecal coliform bacterial contamination of a small estuary in central NC, USA was done relative to adjacent land uses. The area has experienced rapid growth in residential shoreline development including the installation of adjacent, separate docking facilities for larger boats, each <11 slips (pseudomarina) that appear to be a single marina (individual facilities of >10 slips). Six near-shore sites were selected [old developed shore (OD), undeveloped shore (UD), two pseudomarinas (P1, P2), newly developed shore (ND) and a real marina (RM)]. Five locations were spaced along the shore near each site. Paired Thursday/Monday samples were collected biweekly (summer) and monthly (other seasons). Results indicate that OD had the highest bacteria counts followed by ND, RM and P1 & P2. Three sites (OD, ND and RM) failed to meet NC shellfishing waters standards at all locations. At the pseudomarina sites 4 of 10 locations failed to meet shellfish standards while two locations at UD failed to meet these standards. There were no significant differences between paired Thursday/Monday samples. At three sites (OD, UD and P2) bacteria counts were positively correlated with increased water level due to wind tides. CONCLUSIONS: Any type of estuarine shoreline development may result in closing of adjacent shellfishing waters. ND had bacterial counts second only to OD in spite of the retention of vegetated shoreline buffers and very new septic systems. As expected, the RM also failed to meet shellfish standards. Unexpectedly, only four of the 10 pseudomarina locations failed to meet the standards. Weekend boat use had no effect on bacterial counts. Surface runoff from rain and shoreline flooding from increased water levels increased bacterial counts, probably as a result of suspension of surface deposited faeces from wildlife and domestic animals. SIGNIFICANCE AND IMPACT OF THE STUDY: Multiple docking facilities do not necessarily result in violations of shellfish water quality standards. However, the elevated bacterial counts observed along the newly developed shore suggest caution in approving the practice of allowing individual 'oyster gardening' off private piers if the oysters are intended for human consumption. The practice of automatic closure of shellfish waters around RMs was supported. Correlations of bacterial counts with time following significant rainfall suggests a sampling strategy to separate local sources of bacteria from more remote sources thus focusing limited remedial resources more effectively.

Animals↗

PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗

PubMed1998

Modeling of biomass productivity in tubular photobioreactors for microalgal cultures: effects of dilution rate, tube diameter, and solar irradiance

A macromodel is developed for estimating the year-long biomass productivity of outdoor cultures of microalga in tubular photobioreactors. The model evaluates the solar irradiance on the culture surface as a function of day of the year and the geographic location. In a second step, the geometry of the system is taken into account in estimating the average irradiance to which the cells are exposed. Finally, the growth rate is estimated as a function of irradiance, taking into account photoinhibition and photolimitation. The model interconnects solar irradiance (an environmental variable), tube diameter (a design variable), and dilution rate (an operating variable). Continuous cultures in two different tubular photobioreactors were analyzed using the macromodel. The biomass productivity ranged from 0.50 to 2.04 g L-1 d-1, and from 1.08 to 2. 76 g L-1 d-1, for the larger and the smaller tube diameter photobioreactors, respectively. The quantum yield ranged from 1.1 to 2.2 g E-1; the higher the incident solar radiation, the lower the quantum yield. Simultaneous photolimitation and photoinhibition of outdoor cultures was observed. The model reproduced the experimental results with less than 20% error. If photoinhibition was neglected, and a growth model that considered only photolimitation was used to fit the data, the error increased to 45%, thus reflecting the inadequacy of previous outdoor growth models that disregard photoinhibition. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗

PubMed1997

Roles of photoperiod and testosterone in seasonal plasticity of the avian song control system.

The song control nuclei of songbirds undergo pronounced seasonal changes in size and neuronal attributes. The mechanisms by which seasonal changes in environmental variables such as photoperiod mediate seasonal changes in these brain regions are not known. Manipulations of photoperiod and/or testosterone in captive songbirds induce seasonal changes in the size of song nuclei comparable to those observed in wild songbirds. It is unclear, however, whether the effects of photoperiod on the song nuclei are mediated by testosterone or by steroid-independent mechanisms. We independently manipulated photoperiod and testosterone in castrated male Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) to determine the contributions of steroid-dependent and -independent actions of photoperiod to seasonal changes in the size and neuronal attributes of song nuclei. Testosterone implants increased the size of several song nuclei, regardless of photoperiod. Photoperiod exerted small but significant steroid-independent effects on the volume of the higher vocal center and the size of neurons in the robust nucleus of the archistriatum. Photoperiod also modulated the effect of testosterone on the size of area X; testosterone treatment had a more pronounced effect on the size of area X on short days than on long days. These results suggest that although testosterone is the primary factor mediating seasonal changes in neural attributes of the song nuclei, photoperiod may act via mechanisms that are independent of steroid levels to supplement or modulate the actions of testosterone.

Animals↗

PubMed2000

Ultradian clocks in eukaryotic microbes: from behavioural observation to functional genomics.

Period homeostasis is the defining characteristic of a biological clock. Strict period homeostasis is found for the ultradian clocks of eukaryotic microbes. In addition to being temperature-compensated, the period of these rhythms is unaffected by differences in nutrient composition or changes in other environmental variables. The best-studied examples of ultradian clocks are those of the ciliates Paramecium tetraurelia and Tetrahymena sp. and of the fission yeast, Schizosaccharomyces pombe. In these single cell eukaryotes, up to seven different parameters display ultradian rhythmicity with the same, species- and strain-specific period. In fission yeast, the molecular genetic analysis of ultradian clock mechanisms has begun with the systematic analysis of mutants in identified candidate genes. More than 40 "clock mutants" have already been identified, most of them affected in components of major regulatory and signalling pathways. These results indicate a high degree of complexity for a eukaryotic clock mechanism. BioEssays 22:16-22, 2000.

Activity Cycles↗

PubMed1976

Development of a diagnostic checklist for low back pain patients.

The study of psychosomatic disorders implies that environmental variables, as well as attitudes and personality, can influence an individual's physical health. The present study developed a checklist composed of demographic and psychological variables to help to make diagnostic decisions related to chronic low-back pain. The need for the checklist stems from the situation that medical clinical evidence is often inconclusive to identify the etiology of patient complaints of low back pain. Cut-off scores on the checklist were able to discriminate with greater than 80% accuracy patients who received a specific medical diagnosis from patients who received a non-specific medical diagnosis. The findings provide additional support for procedures used to make difficult diagnoses of low back pain.

Adult↗

PubMed1987

Epidemiology of PTSD in a national cohort of Vietnam veterans.

At age 36, Vietnam veterans in the high school class of 1963 reported significantly more problems related to nightmares, loss of control over behavior, emotional numbing, withdrawal from the external environment, hyperalertness, anxiety, and depression than did their classmates matched with them on 51 high school characteristics. These problems correspond closely to the disorder labeled post-traumatic stress disorder (PTSD) by the American Psychiatric Association. PTSD was associated with other family, mental health, and social interaction problems. Some environmental variables--e.g., the presence of a spouse or being a churchgoer--were associated with reduced levels of PTSD or with reductions in the degree of association between combat and PTSD. The direction of cause and effect in these associations cannot be ascertained from our data, but it seems plausible to postulate that support factors can and do help some Vietnam veterans with PTSD.

Adult↗