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PubMed1985

Cellular hyperplasia and hypertrophy, capillary proliferation and myoglobin concentration in the heart of newborn and adult rats at high altitude.

Newborn rats and their mothers were subjected to a simulated altitude of 5000 m for 4-5 weeks. Weight, capillary density (CD), fiber cross-sectional area (AF) and capillary-to-fiber ratio (C/F) of right (RV) and left (LV) ventricles and myocardial myoglobin (Mb) concentration were measured weekly in the newborns and at the end of the high altitude sojourn in the adults. Results were compared to sea level controls. In the adults, adaptive changes were only observed in the right ventricle. In newborns both, RV and LV, exhibited significant alterations. After 2 weeks at 5000 m the ventricular weight increase was 223% (RV) and 40% (LV) in the newborns and 96% in the adults' RV. Whereas only fiber hypertrophy was detectable in the RV of the dams, cardiac weight increase of the acclimatized neonates resulted from both, hypertrophy and hyperplasia of the myocytes. Appropriate capillary proliferation kept CD constant. Cardiac Mb concentration did not change. We conclude, that capillary neoformation primarily counteracts the increase of the O2 diffusion distance due to fiber hypertrophy and/or hyperplasia.

Altitude↗
PubMed1987

Ventilatory adaptation to hypoxia occurs in serotonin-depleted rats.

To test the hypothesis that serotonin mediated respiratory activity is involved in ventilatory adaptation to hypoxia, rats were treated with parachlorophenylalanine (PCPA), a potent, long-acting inhibitor of tryptophan hydroxylase, the rate-limiting enzyme in the biosynthesis of serotonin. In normoxia, a single, intraperitoneal injection of 300 mg PCPA/kg body weight decreased the Paco2 from a control level at 39.1 +/- 0.6 Torr (mean +/- 95% confidence limits) to 34.0 +/- 0.6 Torr measured during a period from 1 to 48 h following PCPA treatment. This PCPA-produced hyperventilation corresponds to an increase of 3.7 +/- 0.5 in the VA (BTPS)/Vco2 (STPD) ratio. Hyperventilation during ventilatory adaptation to hypoxia (PIO2 approximately equal to 90 Torr) was superimposed in an additive fashion on the underlying hyperventilation due to PCPA pretreatment. Specifically, PCPA pretreatment caused an average 3.5 +/- 1.2 increase in the VA/VCO2 ratio determined in acute (1 h) hypoxia, chronic (24 h) hypoxia and acute return to normoxia following chronic hypoxia. Since ventilatory adaptation to hypoxia occurred in rats treated with PCPA, the prolonged, serotonin mediated respiratory activity described by Millhorn et al. (1980b) is probably not important in ventilatory acclimatization to - or deacclimatization from - hypoxia.

Adaptation, Physiological↗
PubMed1995

Hypoxic ventilatory responses in Tibetan residents of 4400 m compared with 3658 m.

Lifelong Tibetan residents of 3658 m ventilate as much and have hypoxic and hypercapnic ventilatory responsiveness as least as great as acclimatized newcomers, and likely greater than lifelong North or South American high-altitude residents. To determine whether Tibetans residing at altitudes > 3658 m maintained similar levels of ventilation, hypoxic and hypercapnic ventilatory responses, we transported 20 lifelong residents of > or = 4400 m to 3658 m for comparison with 27 similarly-aged male Tibetan residents of 3658 m. At 3658 m, the 4400 m compared with the 3658 m Tibetans had similar levels of minute ventilation and arterial O2 saturation, higher respiratory quotients but lower hypoxic ventilatory responses. We conclude that Tibetan residents of > or = 4400 m ventilate as much as Tibetan residents of 3658 m despite an altitude-associated blunting of their hypoxic ventilatory responses. Thus, factors other than hypoxic ventilatory chemosensitivity are likely to be important contributors to resting ventilation among Tibetan high altitude residents.

Adult↗
PubMed1991

19-Nordeoxycorticosterone, aldosterone, and corticosterone excretion in sequential urine samples from male and female rats.

19-Nordeoxycorticosterone (19-norDOC) is a powerful mineralocorticoid that has been postulated to play a role in the pathogenesis of some forms of hypertension in the rat. We measured the daily excretion of 19-norDOC, aldosterone, and corticosterone in intact male and female SR/jr rats for 20 consecutive days. The excretion of corticosterone and aldosterone was higher during the first 4 days of collection and remained relatively stable for the rest of the collection period. The excretion of corticosterone and aldosterone was not different between male and female rats. The excretion of 19-norDOC, which, as has been reported previously, was significantly higher in female than male rats, varied over 600% from day to day in some individual rats. The variability in the excretion of 19-norDOC did not correlate with the excretion of aldosterone or corticosterone and did not appear to coincide with an estrous cycle. These studies also indicate that when the urinary excretion of steroids is intended to be used as an indication of steroid production in the basal state, a period of at least 4 days of acclimatization in metabolic cages, even for animals accustomed to handling, is necessary to obtain stable excretions.

Aldosterone↗
PubMed1984

The influence of milk diet, grain diet, and method of dosing on lead toxicity in young calves.

Twenty 2- to 3-week-old calves were fed a milk diet or a mixture of grain and hay. After acclimatization, all calves were dosed po with lead acetate for 7 days, either in solution via a nursing bottle or in a gelatin capsule. At the end of the treatment period, 6 of 10 calves fed milk were either dead or showed multiple signs of Pb poisoning. All calves fed grain and hay appeared normal. Tissue Pb was significantly higher in calves on a milk diet (p less than 0.05) compared to tissue from calves on a grain and hay diet. No significant differences wee found when dosing methods wee compared. These data clearly show that diet but not dosing methods greatly influenced the absorption and tissue distribution of Pb in calves. delta-Aminolevulinic acid dehydratase (ALAD) activity in blood dropped to approximately 20% of pre-Pb exposure concentrations within 24 hr after the initial dose of Pb and remained at this concentration despite continued Pb administration. Blood Pb concentrations indicate that, in this model, the Pb enters the blood rapidly and retention is prolonged. The calf model warrants further studies on absorption and metabolism.

Animal Feed↗
PubMed1977

Effects of marihuana on reaction time and short-term memory in human volunteers.

Twenty-seven adult male marihuana smokers volunteered to participate in a hospital research ward study for a 31-day period. Following five days of baseline acclimatization, subjects could purchase and smoke marihuana cigarettes on a free choice basis for a period of 21 consecutive days. The marihuana smoking period was followed by a concluding five-day baseline. Measurements of simple reaction time, choice reaction time and short-term memory were carried out during the entire study. Analysis of variance revealed no statistically significant differences between control and marihuana performance; however, a correlational analysis showed that individual subject performances on all three tasks were significantly correlated from test session to test session during control conditions but not during marihuana smoking conditions. Findings are discussed in relation to attentional and motivational factors associated with performance on the three tasks.

Adult↗
PubMed1986

Effect of fenprostalene, a PGF(2)alpha analogue, on plasma levels of estradiol-17beta and progesterone in cyclic heifers.

Following a 40-day acclimatization period, 12 cyclic beef heifers entered a 95- to 101-day test period. Prior to fenprostalene treatment, all animals were studied through two normal estrous cycles. Plasma samples were obtained daily from all animals during the course of the study and were assayed for estradiol-17beta and progesterone. Group 1 heifers (n=6) were then treated with fenprostalene at mid-cycle during two subsequent cycles. This treatment was accomplished by treating the animals 11 days after the first clinically observed signs of estrus following Study Day 21 and treating them again 11 days later. Each treatment consisted of a subcutaneous injection of 1.0 mg fenprostalene. The animals were studied through two or three estrous cycles following the second injection. The Group 2 animals (n=6) were maintained as untreated controls through a corresponding period. Fenprostalene induced estrus in five of six treated heifers within 5 d following the first injection and in five of six heifers within 3 d following the second injection. The mean time to estrus was 3.4 d (+/- 1.1 d SD) following the first injection and 2.2 d (+/-0.8 days SD) following the second injection. No significant differences were found in the plasma levels of estradiol-17beta and progesterone when comparing fenprostalene-induced cycles to those that occurred naturally. The fenprostalene injection reset the estrous cycle without changing the nature of the cycle. The time of clinically detected estrus usually coincided with a sharp peak in estradiol-17beta concentration.

Journal Article↗
PubMed1987

Comparative distribution of petechial haemorrhages as a function of aircraft cockpit geometry.

One of the stresses to which aircrew are subjected in a modern highly manoeuvrable military aircraft is produced by high-speed turns; the resultant elevated G forces may cause petechial haemorrhages, particularly in the lower limbs. Since an aeroplane is an inconvenient laboratory, the mechanisms responsible for these haemorrhages are best investigated by elevated G forces produced in a human centrifuge on the ground, where a similar stress produces the same kind of haemorrhage. Such physical stimuli are in effect a modification of the normal terrestrial gravitational force (a force which under normal conditions is assumed to be +1 G) acting in a + Gz (head to foot) direction. The distribution of petechial haemorrhages is determined by a number of factors, including cockpit configuration. Differences in the distribution of petechial haemorrhages in the F-15 and F-16 aircraft (12 degrees tilt-back seat and 30 degrees tilt-back seat with elevation of the heel, respectively) lend an insight into those body areas where there is inadequate protection. The phenomenon usually begins to develop in healthy individuals at approximately +5 Gz (head to foot), with virtually everyone having petechial haemorrhages at +9 Gz. The kinetics of +Gz -induced petechiasis is interesting, because individuals develop an acclimatized resistance to these formations, whose exact aetiology is unknown; whether or not the petechiae are due to rupture of susceptible capillaries or to diapedesis is also unknown. Stasis and pooling of blood in the lower limbs play a specific role in the petechial formation; it is not only the +Gz stress, but also the protective equipment and techniques which determine the extent and magnitude of the petechiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aircraft↗
PubMedDate not supplied

Children of torture victims: reactions and coping.

The aim of this study was to describe mental reactions and coping strategies among children of torture victims. The study comprised 11 children from 5 exiled families with at least one of the parents having been subjected to torture. Investigation methods applied were qualitative interviews in three different settings and two projective tests. The children were anxious, depressive, and regressive. Moreover, they presented psychosomatic symptoms, sleep disorders, and family and school problems. The children's ways of dealing with their experiences were divided into four main coping strategies: (a) isolation and withdrawal, (b) mental flight, (c) eagerness to acclimatize, and (d) strength of will and fighting. A lack of flexibility in the children's development of coping strategies was mainly explained by the strength of challenges in the families' overall situation before and after escape and exilation. A lack of openness about imprisonment and torture seemed to be an essential way of parental coping. The observation methods chosen all proved to be applicable and informative. Moreover, the qualitative interview showed to be the crucial method.

Adaptation, Psychological↗
PubMed1989

Regulatory detoxication responses in Gobiidae experimentally exposed to PCBs.

In order to investigate interspecific responses to pollutants, physiological and biochemical parameters were studied in two species of Gobiidae under both natural and experimental conditions. Gobius niger, collected in a polluted area, had higher mixed function oxidases activity and polychlorobiphenyl (PCB) residues than another species, Zosterisessor ophiocephalus, collected from a relatively clean lagoon. After acclimatization to clean water and exposure to PCBs (Aroclor 1260), both species showed responses similar to those observed in the field and all biochemical parameters related to detoxication were much higher in G. niger. This suggests that this species undergoes metabolic or genetic adaptation.

Animals↗
PubMed1991

Effects of auditory stimulation during rapid eye movement sleep in healthy volunteers and depressed patients.

Auditory and somesthesic forms of stimulation have substantially increased rapid eye movement (REM) sleep in cats. We investigated whether auditory stimulation, applied during REM sleep or outside REM sleep, would have similar effects in normal volunteers. We also administered auditory stimulation to depressed patients during REM sleep. Subjects were studied during 1 acclimatization night, 2 baseline nights, 4 consecutive nights with auditory stimulation, and 1 followup night without auditory stimulation. Normal volunteers were randomly divided into Group R, which received auditory stimulation during each REM sleep episode, and Group NR, which received auditory stimulation at the end of each REM sleep episode. Depressed patients (Group D) received auditory stimulation during each REM sleep period. Only Group R showed increased REM sleep time during the nights of auditory stimulation and throughout the followup night. This group also increased their sleep efficiency. Group NR showed reduced sleep efficiency due to an increase in both the duration and frequency of awakenings. Group D did not show increased REM sleep time, but did show shortened REM sleep episodes, increased REM sleep frequency, and increased duration of awakenings. Group D did not show clinical changes.

Acoustic Stimulation↗
PubMed1986

Seasonal changes in the humoral immune response and the lymphoid tissues of the marine teleost, Sebastiscus marmoratus.

Seasonal modulation in antibody production in relation to the state of lymphoid tissue development was studied in the ovoviviparous fish, S. marmoratus. Animals were kept in tanks with running seawater at 23 +/- 1 degrees C for a minimum 2 week acclimatization period and then immunized three times at 2 day intervals with 20% SRBC (5 microliters/g body weight) intraperitoneally. Immunized fish were bled 2 weeks after the first injection at the time of peak response and plasma were analyzed for titration. The thymus and pronephros were weighed and the number of leukocytes counted in the cell suspension. Antibody levels in fish immunized in summer were higher than those in fish immunized in winter, even if the environmental temperature was held constant. Furthermore, the reactivity of mature females to SRBC was lower than that of males or immature females in the spawning season (winter). The antibody titre was inversely related to the weight of the thymus with the exception of females during the spawning season, while the weight of the pronephros did not show any significant change throughout the year. In addition, the thymus of pregnant, and especially post-spawning females, was entirely involuted, showing a marked decrease in the number of lymphocytes in both the cortex and medulla. Preliminary experiments to examine the effect of photoperiod on antibody production indicated a slight increase in titre among adult fish under a long photoperiod regimen. The present data show that both the season and stage of sexual maturity affect the humoral immune response and lymphoid tissues, and suggest that the thymus might have a function other than that concerned with immunity.

Animals↗
PubMed1996

Characterization of single chain urokinase-type plasminogen activator with a novel amino-acid substitution in the kringle structure.

ECV304 is a cell line established by a spontaneous transformation of endothelial cells of a human umbilical vein. It was shown that ECV304 secretes single chain urokinase-type plasminogen activator (scu-PA). A subclone, ECV304 clone 15, was obtained by acclimatization of parental clone to serum-free medium followed by limiting dilution. The clone was found to produce approximately five times as much scu-PA (approximately 20 IU/10(6) cells per day) as the parental clone after a 40 days' culture. Though the biochemical characteristics of the purified scu-PA were indistinguishable from those of the native scu-PA, it had a lower affinity for fibrin clots under the employed conditions. Molecular cloning of a cDNA encoding the scu-PA has identified a novel substitution from C to T in the nucleotide sequence encoding the kringle structure. The substitution resulted in an alteration from Pro (CCG) to Leu (CTG) at amino-acid position 121, which may be directly or indirectly involved in the decrease in the apparent affinity.

Amino Acid Sequence↗
PubMed1990

Relationship between heart rate and rhythm, and cardiac performance assessed in the human fetus in utero.

To evaluate the relationship between heart rate and rhythm, and cardiac performance, in the human fetus in utero, observed over a long-term period in gestation, we made a total of 138 studies in 114 fetuses from 18 to 41 weeks of gestation; 104 having heart rate changes without rhythm disturbances ("control group"), 6 with complete atrioventricular block and 4 with supraventricular tachycardia. Using M-mode echocardiogram, we measured end-diastolic dimension and fractional shortening in the right and left ventricles. The corresponding heart rate for each cardiac cycle was measured using the interval between two consecutive end-systolic points. In fetuses in the group of controls, the values for fractional shortening in both ventricles were almost constant with advancing gestational age, unrelated to an increase in end-diastolic dimensions of either ventricle. There was no correlation between changes in heart rate and changes in the value of ventricular fractional shortening at any period of gestation studied. In the fetuses with atrioventricular block, dimensions and fractional shortenings in both ventricles were significantly larger than those in the group of control fetuses at the same stage of gestation. This indicates that the fetal heart is capable of acclimatizing itself, beginning as early as 18-25 weeks of gestation, to long-lasting bradycardia in which an increased stroke volume would be required. In fetuses with supraventricular tachycardia, end-diastolic dimensions were larger and fractional shortening was significantly smaller in both ventricles than in fetuses from the control group from 26-30 weeks of gestation onwards. This suggests tachycardia-induced cardiomyopathy occurring during intrauterine life.

Echocardiography↗
PubMed1992

Metabolic adaptation of myocardial mitochondria to mild altitude hypoxia.

We studied the metabolic parameters of myocardial mitochondria (respiration, respiratory control index, oxidative phosphorylation rapidity and coefficient of oxidative phosphorylation) in two groups of rats: one living at an altitude of 140 m above sea level (control group) and the other living from birth at an altitude of 1350 m above sea level for 2 and 4 months (experimental group). Compared with the control rats, the experimental rats during 2 and 4 months of mild altitude acclimatization increased their basal and stimulated respiration, as well as the rapidity of energy production by myocardial mitochondria. The coefficient of oxidative phosphorylation under mild altitude hypoxia decreased but the respiratory control index did not change. We explain these alterations of heart muscle metabolism at the mitochondrial level as an adaptation to the mild hypoxic conditions.

Altitude↗
PubMed1991

The Sodium-Potassium Blood Pressure Trial in Children. Design, recruitment, and randomization: the children and adolescent blood pressure program.

The Sosium-Potassium Blood Pressure Trial in Children (NaKS), is a clinical trial in a healthy, free living population of children and adolescents. It is designed to test the hypotheses that a reduction in dietary sodium and/or an increase in potassium intake will decrease the rate of rise in blood pressure during normal maturation in children and adolescents with high normal blood pressure. Screening was conducted in 19,452 students in grades 5-8 in Minneapolis and St. Paul between January 1986 and May 1987. After screening, 3,223 students were found to have blood pressures that fulfilled the initial eligibility criteria for the study, and of these, 643 (20.0%) attended the orientation meeting, i.e., the first clinic visit. A total of four clinic visits, designed to test the willingness and capability of the potential participants to comply with the study protocol were conducted prior to randomization. At the conclusion of the four prerandomization visits, 243 children (7.5% of the initially eligible children) agreed to be randomized to one of four trial groups: low-sodium diet; potassium supplement administration; placebo-treated control group; and a no-treatment control group (to test the effect of acclimatization on blood pressure measurements) that will not be seen after randomization until the 4-year termination of the study. The first participant was randomized into the study on June 17, 1986, and the last on December 29, 1987. The potassium and placebo capsules are administered double-masked. Participants will be examined and receive intervention instruction four times yearly for 4 years counted from the date of their randomization. All groups were comparable with regard to distribution of school district, sex, and race and with respect to baseline physical characteristics. Results from this study will provide information about the feasibility and effect of dietary intervention during childhood and adolescence on the prevention of essential hypertension.

Adolescent↗
PubMed1993

Whole-plant growth and leaf formation in ozonated hybrid poplar (Populus x euramericana).

Seasonal growth was studied in potted cuttings of hybrid poplar (one clone of Populus x euramericana) either exposed to ozone in filtered air (0 = control, 0.05, 0.10 microl litre(-1)) or in ambient air (mean = 0.03 microl litre(-1)). Only at 0.10 microl litre(-1) was biomass production reduced and related to leaf loss rather than leaf formation, since the latter was similar in all treatments. Stem length at 0.10 microl litre(-1) approached that of the control, whereas starch concentration in the green stem bark tended to be reduced, as were the ratios of stem weight/length and root/shoot biomass. The changes in carbon allocation and biomass production gradually became established during the second half of the growing season. At the altered carbon allocation at 0.10 microl litre(-1), the ratio of whole-plant production/attached foliage area resembled that of the other O(3) regimes. However, the latter ratio was strongly reduced at 0.10 microl litre(-1) when calculated on the basis of the potential foliage area, as compensated for the O(3)-induced leaf loss. Thus the carbon return/cost balance of the totally formed foliage was low, although the relative-growth rate of ozonated plants temporarily reached that of the control. The relation between leaf differentiation under ozonation (lowered stomatal density) and whole-plant production remains uncertain. The plant behavior found is discussed in terms of passive response or acclimatization to O(3) stress.

Journal Article↗
PubMed1994

PB uptake by ecologically dissimilar earthworm (Lumbricidae) species near a lead smelter in south Finland.

The number of species and individuals, and the total biomass of earthworms decreased with decreasing distance from a lead smelter in southern Finland, as the Pb load of the soil increased. In soils highly polluted with Pb significant interspecific differences were found in the Pb concentration and the Pb concentration factor of lumbricids, whereas in slightly Pb polluted 'control' soils there were no significant interspecific differences. Near the smelter, the Pb concentration of the endogeic Aporrectodea caliginosa was higher than in the epigeic Lumbricus rubellus and L. casteneus. Pb concentration factors of these three species were lower in the highly polluted soil than in the 'control' soil, indicating that they were able to regulate their Pb accumulation. Contradicting these field observations, of the worms from the 'control' soil but reared in highly Pb polluted soil for up to 70 days, the epigeic L. castaneus, L. rubellus and Dendrodrilus rubidus took up more Pb than did the endogeic A. caliginosa and A. rosea. They also accumulated more Pb during the rearing periods than their counterparts permanently living in the highly Pb polluted soil, indicating that besides interspecific differences in Pb accumulation there seem to be intraspecific differences as well. Acclimatization and/or genotype differences can underlie earthworms' adaptation to Pb polluted soil, where they may have dissimilar physiological pathways to cope with high soil Pb concentrations. The amount of Pb rendered available to a local food chain by a population of earthworms will depend on the ability of the worms to accumulate Pb in their tissues, which in turn, is a function of the population's history of Pb exposure. Species such as A. caligonosa, which accumulate and continuously withstand high Pb concentrations in their tissues, are most appropriate for biomonitoring.

Journal Article↗

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