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PubMed2002

Lipid analysis of the response of a sedimentary microbial community to polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAH) are widespread environmental contaminants that can, under proper conditions, be degraded by microorganisms. The responses of a riverine sedimentary microbial community to PAH contamination were examined using an integrated biochemical assay that yielded data on PAH concentration, total microbial biomass, and microbial community structure and were interpreted using perturbation theory and the subsidy-stress gradient. Microbial mineralization of naphthalene, anthracene, fluorene, and phenanthrene was observed 24 h after their addition to all sediments sampled and ranged from 0.9 to 16.3% in ambient sediments and from 14.8 to 35.8% in contaminated sediments. Total microbial biomass, determined by phospholipid phosphate, increased in response to intermediate PAH concentration and decreased at sites with the highest PAH concentration (p < 0.05) during seven out of nine (78%) seasonal sampling periods. The two sampling periods that were not statistically different followed periods of high water and cold temperatures. Phospholipid fatty acid analysis of microbial community structure analysis indicated that increases in the relative abundance of gram-negative aerobes and heterotrophic eukaryotes were responsible, in part, for these observed increases in total microbial biomass. These findings (increased degradation rates, increased biomass at intermediate PAH concentrations, and altered community structure) indicate that a component of the microbial community responded to PAH as a usable input and are consistent with the predictions of perturbation theory and a subsidy-stress gradient.

Biomass↗
PubMed2002

Biosynthesis, biotechnological production and applications of 5-aminolevulinic acid.

Microbial production of 5-aminolevulinic acid (ALA) by photosynthetic bacteria compared to other bacteria and algae is reviewed. During aerobic-microaerobic cultivation of Rhodobacter sphaeroides mutant strain CR520, control of the redox potential was effective for producing large amounts of extracellular ALA. ALA has been practically applied in agriculture as an herbicide, an insecticide and a growth-promoting factor for plants. New agricultural applications including salt tolerance and cold temperature tolerance of plants are also described. Finally, recent medical applications for cancer treatment, tumor diagnosis and other clinical uses are discussed.

Aminolevulinic Acid↗
PubMed2001

Sensitivity of partially purified ice nucleation activity of Fusarium acuminatum SRSF 616.

Factors that affect bacterial ice nucleation, including growth medium, growth phase, nutrient deprivation, and cold-temperature exposure, were investigated in the ice nucleation active (INA) fungus Fusarium acuminatum SRSF 616. Ice nucleation activity remained relatively constant throughout the growth cycle, and the cell-free culture supernatant consistently displayed higher ice nucleation activity than the hyphal pellet. Although nutrient starvation and low-temperature exposure enhance bacterial ice nucleation activity, reducing the concentration of C, N, or P in synthetischer nährstoffarmer broth (SNB) did not increase fungal ice nucleation activity, nor did exposure to 4 degrees C or 15 degrees C. From the SNB supernatant, selected INA chromatography fractions were obtained that demonstrated increased sensitivity to proteinase K and heat compared with culture supernatant. We propose that partial purification of the fungal ice nuclei resulted in removal of low-molecular-weight stabilizing factors.

Culture Media↗
PubMed2006

Regulation of the beta-hydroxyacyl ACP dehydratase gene of Picea mariana by alternative splicing.

The gene for beta-hydroxyacyl ACP dehydratase, a de novo fatty acid biosynthetic enzyme, was cloned from Picea mariana (black spruce) and consists of five exons and four introns. The first intron of the beta-hydroxyacyl ACP dehydratase mRNA is alternatively spliced. Retention of intron 1 in splice variants results in truncation of the beta-hydroxyacyl ACP dehydratase ORF at a premature termination codon. In addition, splicing of intron 1 was found to be associated with cold temperature. mRNAs retaining intron 1 increase with seed imbibition at 22 degrees C but not 4 degrees C, whereas, splicing of intron 1 increases in winter weeks with temperatures below freezing. These results provide evidence that alternative splicing may also contribute to regulation of lipid biosynthesis in Picea mariana.

Alternative Splicing↗
PubMed2006

Delayed flowering time in Arabidopsis and Brassica rapa by the overexpression of FLOWERING LOCUS C (FLC) homologs isolated from Chinese cabbage (Brassica rapa L.: ssp. pekinensis).

Chinese cabbage plants remain in the vegetative growth phase until they have experienced prolonged exposure to cold temperature, known as vernalization. This inhibition of flowering is caused by the high levels of FLOWERING LOCUS C (FLC) expression. To increase the product value of Chinese cabbage by inhibiting the floral transition, three genes (BrFLC1, BrFLC2, and BrFLC3) homologous to the AtFLC gene, which encodes a floral repressor, were isolated from the Chinese cabbage 'Chiifu'. These genes showed high similarity to AtFLC, although the putative BrFLC1 protein contained ten more residues than AtFLC. The BrFLC genes were expressed ubiquitously, except that BrFLC3 was not expressed in roots. BrFLC1 and BrFLC2 showed stronger expression than BrFLC3 in unvernalized and vernalized Chinese cabbage. The expression levels of the three BrFLC genes were lower in an early-flowering Chinese cabbage, suggesting that the BrFLC transcript level was associated with flowering time. Constitutive expression of the BrFLC genes in Arabidopsis significantly delayed flowering, which was also observed in transgenic Chinese cabbage overexpressing BrFLC3. These results suggest that the BrFLC genes act similarly to AtFLC. Our results provide a technique for controlling flowering time in Chinese cabbage and other crops to produce high yields of vegetative tissues.

Amino Acid Sequence↗
PubMed2001

Physiological responses to supercooling and hypoxia in the hatchling painted turtle, Chrysemys picta.

We investigated physiological responses to supercooling in hatchling painted turtles (Chrysemys picta) which remain in their natal nests over winter and therefore may become exposed to subzero temperatures. These turtles are freeze tolerant but also must rely on supercooling to survive exposure to the lower temperatures occurring in nests during winter. We compared whole-body concentrations of lactate, glucose, glycerol, and ATP in turtles chilled at 0 degrees C, -4 degrees C, or -6 degrees C for 5 days, or at 6 degrees C for 19 days. In a companion experiment, we measured metabolite concentrations in turtles exposed to a hypoxic environment for 1 day, 4 days, or 8 days. Supercooling and hypoxia exposure were both associated with an increase in concentrations of lactate and glucose and a decrease in glycerol concentrations (albeit no change in the ATP pool), suggesting that supercooling induces functional hypoxia. We conclude that hypoxia tolerance may be an important pre-adaptation for surviving exposure to subzero temperatures in hatchling C. picta.

Animals↗
PubMed2005

Impact of urban air pollutants and noise levels over daily hospital admissions in children in Madrid: a time series analysis.

OBJECTIVE: The aim of this paper was to analyse the effects of the urban air pollutants and noise levels on daily emergency hospital admissions of children less than 10 years of age in Madrid. MATERIAL AND METHODS: Poisson Regression Models were used to quantify the associations. Meteorological variables, influenza epidemics, pollen concentrations and trends and periodicities were used as controlling variables. RESULTS: The main results obtained were the detected relationship (p<0.05) between emergency hospital admissions due to organic diseases and noise levels (AR=2.4%) and for PM(10) concentrations (AR=2.1%). For respiratory diseases statistically significant associations were detected for noise levels (AR=4.7%) and cold temperatures (AR=3.8%). The main association detected for causes of admissions due to bronchitis was for O(3) (AR=36.8%) and for pneumonia was for noise levels (AR=7.7%). CONCLUSION: The results obtained suggest that noise level particularly is a risk factor for daily emergency hospital admissions for organic and respiratory diseases in children less than 10 years old in Madrid.

Air Pollutants↗
PubMed2004

Lowering of skin temperature decreases isokinetic maximal force production independent of core temperature.

Based on studies using maximal isometric contractions, it is suggested that fatigue may be elicited due to hyperthermia-induced impairments in central neuromuscular activation. We investigated the effects of passive hyperthermia on isokinetic maximal force production. Twenty young healthy males [peak oxygen uptake 52.9 (6.8) ml x kg(-1) min(-1), body fat 11 (5)%] were passively warmed in a hot (42 degrees C) water bath to rectal temperature ( T(re)) of 39.5 degrees C and then cooled back to 38.0 degrees C. At 0.5 degrees C intervals, they performed two maximal voluntary knee extensions each at 60, 120, and 240 s(-1). Peak torques at 37.5 degrees C were 168 (34), 145 (29), and 112 (17) N m for 60, 120, and 240 s(-1) contraction speeds, respectively, and 166 (38), 150 (31), and 119 (17) N m at T(re) of 39.5 degrees C. No significant differences in peak torque at any of the three contraction speeds were observed over the range 37.5-39.5 degrees C. Skin cooling, even with a warm core of 39.5 degrees C, immediately decreased peak torque [159 (42), 133 (34), 107 (22) N m at 60, 120, and 240 s(-1), respectively). We conclude that lowered skin temperature can impair isokinetic force production independent of core temperature.

Adaptation, Physiological↗
PubMed2004

Passive hyperthermia reduces voluntary activation and isometric force production.

It has been suggested that a critically high body core temperature may impair central neuromuscular activation and cause fatigue. We investigated the effects of passive hyperthermia on maximal isometric force production (MVC) and voluntary activation (VA) to determine the relative roles of skin (T(sk)) and body core temperature ( T(c)) on these factors. Twenty-two males [VO(2max)=64.2 (8.9) ml x kg(-1) min(-1), body fat=8.2 (3.9)%] were seated in a knee-extension myograph, then passively heated from 37.4 to 39.4 degrees C rectal temperature (T(re)) and then cooled back to 37.4(o)C using a liquid conditioning garment. Voluntary strength and VA (interpolated twitch) were examined during an isometric 10-s MVC at 0.5 degrees C intervals during both heating and cooling. Passive heating to a T(c) of 39.4(o)C reduced VA by 11 (11)% and MVC by 13 (18)% (P<0.05), but rapid skin cooling, with a concomitant reduction in cardiovascular strain [percentage heart rate reserve decreased from 64 (11)% to 29 (11)%] and psychophysical strain did not restore either of these measures to baseline. Only when cooling lowered T(c) back to normal did VA and MVC return to baseline (P<0.05). We conclude that an elevated T(c) reduces VA during isometric MVC, and neither T(sk) nor cardiovascular or psychophysical strain modulates this response. Results are given as mean (SD) unless otherwise stated.

Adaptation, Physiological↗
PubMed2004

Effects of brief leg cooling after moderate exercise on cardiorespiratory responses to subsequent exercise in the heat.

We investigated the effects of brief leg cooling after moderate exercise on the cardiorespiratory responses to subsequent exercise in the heat. Following 40 min of ergometer cycling [65% peak oxygen uptake (VO(2peak))] at 35 degrees C (Ex. 1), seven male subjects [21.9 (1.1) years of age; 170.9 (1.9) cm height; 66.0 (2.0) kg body mass; 46.7 (2.0) ml kg(-1) min(-1) VO(2peak)] immersed their legs in 35 degrees C (control condition, CONT) or 20 degrees C (cooling condition, COOL) water for 5 min and then repeated the cycling (as before, but for 10 min) (Ex. 2). Just before Ex. 2, esophageal temperature ( T(es)) was lower in COOL than in CONT [36.9 (0.2) vs 37.5 (0.1) degrees C] ( P<0.01), as also were both mean skin temperature [33.9 (0.2) vs 35.2 (0.2) degrees C] ( P<0.01), and heart rate (HR) [93.2 (6.0) vs 102.7 (4.9) beats min(-1)] ( P<0.05). During Ex. 2, no differences between CONT and COOL were observed in oxygen uptake, arterial blood pressure, blood lactate concentration, or ratings of perceived exertion; however, T(es), skin temperature, and HR were lower in COOL than in CONT. Further, during the first 5 min of Ex. 2, minute ventilation was significantly lower in COOL than in CONT [50.3 (2.0) vs 53.4 (2.6) l min(-1)] ( P<0.01). These results suggest that brief leg cooling during the recovery period may be effective at reducing thermal and cardiorespiratory strain during subsequent exercise in the heat.

Adult↗
PubMed2005

Safe cooling limits from exercise-induced hyperthermia.

We evaluated the cooling rate of hyperthermic subjects, as measured by three estimates of deep core temperatures (esophageal, rectal and aural canal temperatures), during immersion in a range of water temperatures. The objective of the study was to compare the three indices of core temperature and define safe cooling limits when using rectal temperature to avoid the development of hypothermia. On 4 separate days, seven subjects (four males, three females) exercised for 45.4+/-4.1 min at 65% V(O2)max at an ambient temperature of 39 degrees C, RH: 36.5%, until rectal temperature (T (re)) increased to 40.0 degrees C (39.5 degrees C for two subjects). Following exercise, the subjects were immersed in a circulated water bath controlled at 2, 8, 14 and 20 degrees C until T (re) returned to 37.5 degrees C. When T (re) reached normothermia during the cooling period (37.5+/-0.05 degrees C), both esophageal (T (es)) (35.6+/-1.3 degrees C) and aural canal (T (ac)) (35.9+/-0.9 degrees C) temperatures were approaching or reaching hypothermia, particularly during immersion in 2 degrees C water (T (es)=34.5+/-1.2 degrees C). On the basis of the heat loss data, the heat gained during the exercise was fully eliminated after 5.4+/-1.5, 7.9+/-2.9, 10.4+/-3.8 and 13.1+/-2.8 min of immersion in 2, 8, 14 and 20 degrees C water, respectively, with the coldest water showing a significantly faster cooling rate. During the immersion in 2 degrees C water, a decrease of only 1.5 degrees C in T (re) resulted in the elimination of 100% of the heat gained during exercise without causing hypothermia. This study would therefore support cooling the core temperature of hyperthermic subjects to a rectal temperature between 37.8 degrees C (during immersion in water >10 degrees C) and 38.6 degrees C (during immersion in water <10 degrees C) to eliminate the heat gained during exercise without causing hypothermia.

Adult↗
PubMed2000

Influence of muscle temperature during fatiguing work with the first dorsal interosseous muscle in man: a 31P-NMR spectroscopy study.

Six healthy subjects rapidly lifted and lowered a small (250 g) weight with the first dorsal interosseous muscle (FDI) of one hand while the work performed was recorded continuously until fatigue (defined as losing the ability to continue lifting). Work was recorded in units of chart recorder trace displacement from baseline (centimeters) as an isotonic transducer followed the movement of the weight. In all experiments, the temperature of the hand was first adjusted by immersion in a controlled-temperature water bath. In the warmest condition, the skin surface temperature over the FDI was 30.5(0.30) degrees C [mean (SE)]. After moderate cooling, this surface temperature was 21.5(0.16) degrees C. Cooling significantly reduced the time taken to reach fatigue and more than halved the work capacity. An intermediate degree of cooling was also used in four subjects, showing that most of the effects seen were changing incrementally. Before work, and at fatigue, intracellular metabolic conditions in the FDI were studied by phosphorus nuclear magnetic resonance (31P-NMR) spectroscopy, with occlusion of the blood flow maintained during measurements. The mean intracellular pH of the FDI was also calculated. The changes observed were all consistent with the fact that intense work requires energy which must be derived largely from intracellular stores of phosphocreatine and glycogen. Less work made less demand upon reserves, and created lower concentrations of waste products and by-products. The observations did not, however, allow us to explain why fatigue occurred at a particular point or why work capacity was reduced by cooling.

Adult↗
PubMed2003

Effects of head cooling on human sleep stages and body temperature.

The purpose of this study was to confirm the effect of head cooling on human sleep stages and body temperature. Nine healthy male volunteers with a mean age of 25 +/- 3.77 years served as subjects. The experiments were carried out under three different sets of conditions: 26 degrees C, relative humidity (RH) 50% (26/50); 32 degrees C, RH 80% (32/80); and 32 degrees C RH 80% with the use of a cooling pillow (32/80 HC). The subjects slept from 2300 hours to 0700 hours with a cotton blanket, wearing short-sleeved pyjamas and shorts on a bed, which was covered with a sheet. Electroencephalograms, electro-ouclogram, and mental electromyelograms were recorded through the night. Rectal temperature (Tre) and skin temperature (Tsk) were measured continuously. Whole-body sweat and the tympanic temperature (Tty) were measured before and after sleep. Wakefulness significantly increased at 32/80 than at 26/50; however, no significant difference was observed between 32/80 HC and 26/50. Tre and mean Tsk were higher both at 32/80 and 32/80 HC than at 26/50. The whole-body sweat loss was significantly greater and Tty in the morning was higher at 32/80 than 32/80 HC and 26/50. These results suggest that head cooling during sleep may help to decrease the whole-body sweat rate during sleep under humid heat conditions.

Adult↗
PubMed2003

Current Treatment Options in Raynaud's Phenomenon.

The treatment of Raynaud's phenomenon (RP) strictly depends on the severity of symptoms and on the presence of an underlying systemic disease. For this reason, any patient with RP should be carefully assessed for signs and symptoms that may herald an underlying disease. Primary RP can usually be managed with conservative nonpharmacologic lifestyle modifications (eg, avoidance of cold temperatures, tobacco, caffeine, and any drug interfering with vascular tone) and pharmacologic treatment added only if attacks are poorly controlled. Vasodilating drugs (eg, calcium channel blockers, angiotensin II receptor antagonists, topical nitrates, and prostanoids) are still the mainstay of medical therapy for RP. Anecdotal reports with different kinds of therapies appear regularly but always need evidence-based confirmation. In particular, antioxidant agents may be useful in limiting the progressive endothelial damage. Novel therapeutic tools interfering either with primary or secondary pathogenetic processes (ie, endothelial and peripheral nervous system dysfunction and smooth muscle cell hypertrophy) are awaited.

Journal Article↗
PubMed2026

Using Organoids to Unlock the Potential of Human Torpor for Spaceflight.

PURPOSE OF REVIEW: This paper reviews the current understanding of the potential for humans to enter a state of torpor/hibernation, and discusses the possibility of inducing torpor in astronauts for long-duration space travel, including some of the physiological, technological, and ethical considerations associated with its implementation. By exploring means to induce torpor in various human organoid systems, we hope such research can provides insights to comprehensive solutions to overcome some of the major hurdles that limit the potential for human to enter a state of torpor during long-duration deep-space missions, and contribute to the ongoing efforts to make such missions more feasible and safer for astronauts. RECENT FINDINGS: On future deep space missions such as NASA's planned missions to the Moon, Mars, and near-Earth asteroids, astronauts will be continuously exposed to environments that are radically different from those on Earth, each presenting multiple logistical and physiological challenges. Beyond the well-documented physiological effects of microgravity, space travelers will encounter a complex radiation environment that may contribute to significant short- and long-term adverse effects on human physiology and increase the risk of cancer and other diseases. Besides these physical challenges, life support systems must also be designed to mitigate psychological impacts of long-term isolation and confinement - all of which collectively pose formidable engineering problems. Hibernation/torpor is a state of prolonged inactivity and metabolic depression used by a wide variety of mammals to survive periods of cold temperatures and food scarcity, including some primates and perhaps even an extinct early line of hominins that lived nearly half a million years ago. Since modern humans share common ancestry with these hominins and hibernating primates, it is likely the human genome encodes the necessary genetic information to hibernate, or at least enter the similar, more transient state of torpor. The reduced body activity, lowered metabolism, and decreased energy requirements that characterize torpor suggest that developing means of inducing such a state in astronauts could address these challenges, including providing a degree of radioprotection. SUMMARY: This review explores the potential application of human torpor as a countermeasure to address the many challenges posed by long-duration spaceflight beyond low-Earth orbit (LEO), discusses various natural hibernating model systems for studying means of inducing a torpor-like state in humans, and highlights the vast potential of using human organoids to test and validate mechanisms that govern induction and maintenance of torpor to identify the means to one day safely induce this state in astronauts to provide additional protection from the myriad stressors of spaceflight.

Astronaut Health↗
PubMed1989

Fish-oil dietary supplementation in patients with Raynaud's phenomenon: a double-blind, controlled, prospective study.

PURPOSE: The ingestion of omega-3 fatty acids could benefit patients with Raynaud's phenomenon because, among other effects, these fatty acids induce a favorable vascular response to ischemia. The aim of our study was to investigate, in a double-blind, placebo-controlled manner, the effects of fish-oil fatty-acid dietary therapy in patients with rheumatic disease. PATIENTS AND METHODS: Thirty-two patients with primary or secondary Raynaud's phenomenon were randomly assigned to olive-oil placebo or fish-oil groups. Patients ingested 12 fish-oil capsules daily containing a total of 3.96 g eicosapentaenoic acid and 2.64 g docosahexaenoic acid or 12 olive-oil capsules and were evaluated at baseline and after six, 12, and 17 weeks. All patients ingested olive oil between Weeks 12 to 17. Digital systolic blood pressures and blood flow were measured at room air and water baths of 40 degrees C, 25 degrees C, 15 degrees C, and 10 degrees C using strain gauge plethysmography. Onset of Raynaud's phenomenon was timed with a stop watch and defined as plethysmographic evidence of cessation of blood flow and blood pressure in the study finger. RESULTS: In the fish-oil group, the median time interval before the onset of Raynaud's phenomenon increased from 31.3 +/- 1.3 minutes baseline to 46.5 +/- 2.1 minutes at six weeks (p = 0.04). Patients with primary Raynaud's phenomenon ingesting fish oil had the greatest increase in the time interval before the onset of the condition. Five of 11 patients (45.5 percent) with primary Raynaud's phenomenon ingesting fish oil in whom the phenomenon was induced at baseline could not be induced to develop Raynaud's at the six- or 12-week visit compared with one of nine patients (11 percent) with primary Raynaud's ingesting olive oil (p = 0.05). The mean digital systolic pressures were higher in the patients with primary Raynaud's phenomenon ingesting fish oil than in patients with primary Raynaud's ingesting olive oil in the 10 degrees C water bath (+32 mm Hg, p = 0.02). CONCLUSION: We conclude that the ingestion of fish oil improves tolerance to cold exposure and delays the onset of vasospasm in patients with primary, but not secondary, Raynaud's phenomenon. These improvements are associated with significantly increased digital systolic blood pressures in cold temperatures.

Adult↗
PubMed1988

Assessment of a cold air breathing aid.

During nasal breathing, heat and humidity are exchanged over a 160 cm(2) area of mucous membrane. This capacity is not sufficient for airway comfort during cold air breathing. Similarly, airway discomfort and constriction may be experienced during exercise-induced mouth breathing in marginally cold temperatures. In asthmatics and sensitive persons such airway discomfort rapidly transforms to broncho-constriction and related breathing problems. The Lungplus mouth-held breathing aid contains a coil of corrugated aluminium foil that provides a heat and moisture exchange area of 1200 cm(2) (Model 1) with a minimal breathing resistance. The present experiment was designed to quantify improved airway comfort using the device. Ninety-one subjects were exposed to each of three rooms with average air temperatures of +20, +3 and -15 degrees C, with a corresponding relative humidity of 50, 70 and 90%. For each condition, subjects gave subjective numerical assessments of the airway sensation during nose, mouth and Lungplus breathing, respectively. At each room temperature, mouth breathing resulted in a less comfortable airway rating than did breathing through the nose, which in turn resulted in a less comfortable rating than the Lungplus breathing condition.

Journal Article↗