[Physiological observations on the adaptation to altitude in Caucasus].
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Acclimatization↗
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Proctocolectomy and quadruple-limb W pouch reconstruction for the management of pediatric ulcerative colitis and familial polyposis.
Proctocolectomy with ileal pouch-anal anastomosis (IPAA) has become the procedure of choice for many children with ulcerative colitis and familial polyposis. The modified quadruple-limb (W) IPAA was designed to increase reservoir compliance and capacity, and to improve functional results by decreasing stool frequency. However, only limited information has been reported concerning the technical considerations and functional outcomes from W IPAA modification and utilization in the pediatric population. Additionally, pediatric IPAA physiological adaptation, expressed as IPAA volume/pressure relationships, for any type of IPAA design has not been described. In this report, the authors analyze their functional and physiological results with W IPAA in 19 children undergoing colectomy for ulcerative colitis and familial polyposis. Since 1986, 19 children (5 girls, 14 boys; mean age, 15.3 years [range, 11 to 18 years]) have undergone proctocolectomy with W IPAA for ulcerative colitis (n = 9) and familial polyposis (n = 10). IPAA pressure and volume profiles were measured in 10 patients at 2 and 12 months postileostomy takedown, and in five patients at 3 years. W IPAA compliance was calculated as the change in volume over change in pressure (delta V/delta P). There were no deaths, anastomotic leaks, or pelvic sepsis. The 24-hour stool frequency (mean +/- SEM) decreased significantly (P < or = .05) from 4.6 +/- 0.6 at 2 months to 3.3 +/- 0.1 at 12 months. No nighttime evacuation occurred after 12 months. W IPAA evacuation volume significantly increased (P < or = .05) from 238 +/- 22.9 mL at 2 months to 346 +/- 26.5 mL at 12 months and remained stable thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)
Adaptation, Physiological↗
Adaptations to daily exercise in hot and humid ambient conditions in trained thoroughbred horses.
The objectives of this study were to: 1) determine the effects of heat and high relative humidity (RH) on the clinical and physiological responses of horses during and after daily exercise training and 2) determine whether repeated exposure to, and exercise in, the heat would result in improved thermal tolerance (heat acclimation). Six trained Thoroughbred horses completed 1 h of submaximal exercise in cool, dry conditions (CD) and during a daily 4 h period of exposure to high heat and humidity (HH, room temperature = 33-35 degrees C, RH = 80-85%) for 22 days. Rectal temperature (Tre) and heart rate (HR) were measured before, during and after exercise and respiratory rate (RR) was measured before exercise and during a 2 h recovery. In HH, the rate of rise in Tre was significantly higher than in CD. However, by HH Day 5, Tre before, during and after exercise was significantly lower than on HH Day 1. The day-to-day decrease in Tre during exercise was reflected in significant decreases in heat storage following exercise by HH Day 10 (910 +/- 47 kcal) when compared to HH Day 1 (1211 +/- 75 kcal). At rest, RR was initially higher in HH than CD, and a further increase in pre-exercise RR from HH Day 1 to Day 10 may have contributed to the lower pre-exercise Tre. Recovery RR was higher after HH Day 1 and was associated with a lower end-of-exercise HR did not change in the 1 h before exercise in CD and did not differ from HH Days 1-22. By HH Day 10, mean HR during the latter part of exercise was lower than HH Day 1 and was not different from pre-exercise by 60 min of recovery. Pre-exercise body mass did not change during the 3 wk period and the decrease in body mass that occurred during the 4 h training period was significantly attenuated by HH Day 15 (9.8 +/- 0.8 kg) when compared to HH Day 1 (12.5 +/- 0.8 kg). Over the 3 week period of HH, mean 24 h water consumption increased from 26.0 +/- 2.1 litres to 39.5 +/- 3.2 litres, largely reflecting a 2-fold increase in water intake during the 4 h period of heat exposure. It is concluded that 3 weeks of daily exposure to, and exercise in, hot and humid ambient conditions resulted in a progressive reduction in thermal and cardiovascular strain. Furthermore, the reported physiological adaptations are consistent with an improved thermal tolerance (heat acclimation).
Adaptation, Physiological↗
[Adaptive duodenal endocrine cell changes after antrectomy. Experimental study in the rat].
The known gastric endocrine relationship between "G" cells and "D" cells is altered after the loss of antral "G" cell population after antrectomy, leading to physiologic adaptative changes over the cell population producing gastrin and somatostatin in the duodenum, replacing thus the endocrine function of the resected gastric antrum. In this experimental study, Sprague-Dawley rats have been randomized in two groups, Control and Antrectomy with gastroduodenostomy, maintaining the alimentary stimulation of the duodenum. Endocrine "G" and "D" cell studies have been carried out by immunohistochemical staining with an Avidin-Biotin affinity technique. The statistical method used was the "t" test of Student. The results demonstrated a significant increase of the duodenal "G" cell population without changes of the duodenal "D" cell population after antrectomy and gastroduodenostomy. The endocrine cell ratio "G/D" in the duodenum increases due to the loss of antral gastrin release and the decrease of gastric acid output provoked by antrectomy.
Adaptation, Physiological↗
Influence of dietary calcium chloride on adaptive changes in acid-base status and mineral metabolism in lactating dairy cows fed a diet high in sodium bicarbonate.
Eight mature, lactating Holstein cows were assigned to two treatments in a simple changeover design to examine physiological adaptations to dietary NaHCO3 over a 2-wk period. Treatments were diets containing, on a total diet DM basis, 1) 1.4% NaHCO3 and 2) 1.4% NaHCO3 with 1.3% CaCl2 substituted for limestone. Blood samples were collected hourly, and urine samples bihourly, for 8 h postfeeding on the 1st d of the experimental period and daily at 4 h post-feeding thereafter. Hourly analysis revealed that for most variables measured, the greatest response to dietary treatments occurred at or after 4 h post-feeding. Blood pH and blood HCO3- tended to be lower, and urinary excretion of chloride higher, on 1.4% NaHCO3 plus 1.3% CaCl2 throughout the trial. Blood HCO3- and blood partial pressure of CO2 fluctuated in response to the dietary treatments but functioned to maintain blood pH fairly constant. Plasma K concentration tended to increase during the experimental period on both treatments, but overall, plasma mineral concentration was relatively unresponsive to diet, and urinary mineral excretion was an excellent indicator of dietary mineral concentration. Inherent homeostatic mechanisms appear adequate to maintain a constant internal milieu when a high NaHCO3 diet is fed for 2 wk.
Acid-Base Equilibrium↗
Adaptation of left ventricular morphology to long-term training in sprint- and endurance-trained elite runners.
Long-term studies on left ventricular (LV) adaptation have not been reported. The echocardiograms of 41 top-class runners (8 males and 6 females sprint-trained, 15 males and 12 females endurance-trained) were recorded at the beginning and after 1, 2, and 3 years of training. A one-way ANOVA and a linear regression analysis were conducted to determine changes and association between performance and LV values. Training resulted in an increase in performance and LV internal diameter at end-diastole (LVIDd) and decreases in end-diastolic interventricular septal wall thickness, and posterior wall thickness (PWTd). There were no significant differences in LV mass and LV ejection fraction (LVEF, %). The changes in PWTd were linked to enlargement of the LV. In athletes with unusual LV dilatation (>60 mm), LVIDd was related to performance and LVEF was >50%. Maximal wall thickness was <13 mm in all athletes. LV adaptations were independent of sex and type of training and related to the initial level of performance. We believe that LV enlargement in elite runners is a physiological adaptation and that the LVIDd is a predictor of running performance.
Adaptation, Physiological↗
Left ventricular morphology and function in female athletes: a meta-analysis.
The purpose of the present study was to examine the impact of physical training upon cardiac structure and function, and identify physiologic upper limits in female athletes. Meta-analytical techniques were applied to 13 published echocardiographic studies examining cardiac structure and function in female athletes. The study group included 890 athletes and 333 controls. For comparison of sporting discipline, studies were partitioned into 3 categories (endurance, strength/sprint, team). Significant (p < 0.05) effect sizes were observed for all structural measures between athletes and controls. Significant effect size differences existed between sporting groups for LVIDd and LVM only, with endurance and team game athletes demonstrating the largest effect sizes compared to strength trained athletes. No significant effect of training was observed for left ventricular diastolic or systolic function, with the exception of stroke volume where a significant effect size difference was observed between athletes and controls with no observed difference between sporting groups. Maximum reported upper limits for LV wall thickness and LVIDd in female athletes were 12 mm and 66 mm respectively. Chronic exercise training results in cardiac enlargement in female athletes. The nature of physiologic adaptation is similar to that observed in male athletes. LV wall thickness values greater than 12 mm in female athletes should be viewed with caution and indicate a more comprehensive evaluation to establish a physiological or pathological basis for the observed left ventricular enlargement.
Adaptation, Physiological↗
BEHAVIORAL AND 17-HYDROXYCORTICOSTEROID CHANGES FOLLOWING PNEUMOENCEPHALOGRAPHY.
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17-Hydroxycorticosteroids↗
Physiological and histochemical adaptation of the electrically stimulated gracilis muscle to neoanal sphincter function.
The physiological and histochemical characteristics of the gracilis muscle were studied in 19 patients undergoing electrically stimulated gracilis neosphincter construction. Indications for surgery were faecal incontinence (n = 11) and reconstruction following sphincter excision or congenital absence (n = 8). Transposition of the gracilis muscle around the anal canal followed by chronic low-frequency electrical stimulation was associated with a shift in the frequency-response curve and a prolongation of the time-course of individual muscle twitches suggestive of transformation to a slow-twitch fatigue-resistant type. Temporary cessation of electrical stimulation resulted in a reversal of the frequency-response changes. Muscle biopsies taken before and a median of 80 (range 49-137) days after transposition and low-frequency electrical stimulation indicated a significant increase in the proportion of type 1 fibres and a significant decrease in their diameter. These results show that the human gracilis muscle is capable of physiological and histochemical adaptation to long-term neosphincter function.
Adaptation, Physiological↗
Local adaptation across a climatic gradient despite small effective population size in the rare sapphire rockcress.
When assigning conservation priorities in endangered species, two common management strategies seek to protect remnant populations that (i) are the most genetically divergent or (ii) possess the highest diversity at neutral genetic markers. These two approaches assume that variation in molecular markers reflects variation in ecologically important traits and ignore the possibility of local adaptation among populations that show little divergence or variation at marker loci. Using common garden experiments, we demonstrate that populations of the rare endemic plant Arabis fecunda are physiologically adapted to the local microclimate. Local adaptation occurs despite (i) the absence of divergence at almost all marker loci and (ii) very small effective population sizes, as evidenced by extremely low levels of allozyme and DNA sequence polymorphism. Our results provide empirical evidence that setting conservation priorities based exclusively on molecular marker diversity may lead to the loss of locally adapted populations.
Adaptation, Physiological↗
A review to develop an effective exercise training for heart failure patients.
The patient with heart failure relies on varied physiological adaptations to exercise training. Although, the cardiovascular adaptations may be limited, the patient with heart failure relies on changes in the pulmonary system as well as peripheral muscular adaptations. Therefore, the intent of this review is to outline effective exercise program design and to discuss the effects of exercise training on the patient with heart failure, including cardiovascular, pulmonary, and peripheral musculature adaptations. As a result of exercise training, patients with heart failure can improve their exercise capacity and quality of life, despite no or reduced improvement in central hemodynamics. Respiratory muscle endurance improves with exercise training which contributes to patients' increased exercise capacity, decreased breathlessness, and decreased perception of breathlessness. In addition, peripheral muscle adaptations result in an enhanced ability for oxygen extraction and utilization, a delayed onset of anaerobic metabolism during physical activity, and less fatigue as a result of physical activity and activities of daily living. Many of the physiological sequela associated with reduce functional ability in heart failure patients are correctable with exercise training. The practical implications (and maybe the most important to the patient) of these positive adaptations include less frequent rest periods, lesser overall fatigue, greater confidence to embark on physical tasks, maintenance of independence, and enhanced quality of life.
Adaptation, Physiological↗
The strategic role of exercise devices in manned spaceflight.
Exercise appears in various contexts during spaceflight. It serves as a key countermeasure against adverse physiological adaptation processes; it also plays a role in life sciences research as reference state or stimulus. Further aspects concern human factors, recreational activities, health monitoring and training for emergency egress and extra-vehicular activities. Current approaches rely on conventional ergometers, they add rather than integrate training programs, and they tend to disregard applications other than "countermeasures". Two major consequences are an appreciable impact on available crew-time and an unsolved problem: Exercise countermeasures use extrapolations of 1g-physiology in order to eliminate what physiologists would like to study: adaptation to weightlessness. New concepts and devices are required to reconcile such conflicting demands and to reduce time consumption for physical training. Key elements are an improved simulation of terrestrial locomotion and a recombination of work and physical exercise. The GRASIM device will be presented as an example for a new generation of multi-purpose "exercisers".
Adaptation, Physiological↗
Adaptations to fasting in the American mink (Mustela vison): carbohydrate and lipid metabolism.
The aim of this study was to investigate whether the actively wintering American mink Mustela vison is strictly dependent on continuous food availability or if it has evolved physiological adaptations to tolerate nutritional scarcity. Fifty farm-bred male minks were divided into a fed control group and four experimental groups fasted for 2, 3, 5 or 7 days. The rate of weight loss was several-fold higher (1.5-3.2% day(-1)) in the mink than recorded previously in larger carnivores utilizing passive wintering strategies. The minks remained normoglycaemic, although their liver glycogen stores and glucose-6-phosphatase activities decreased during fasting. Adipose tissue constituted approximately 36% of their body mass after 7 days of food deprivation. Intra-abdominal fat, especially retroperitoneal but also mesenteric adipose tissue, were the most important fat depots to be hydrolyzed, but the ability of the mink to utilize its body lipids during fasting may be limited. The increased liver size, hepatic triacylglycerol accumulation and increases in the activities of plasma aminotransferases indicated liver dysfunction. Food deprivation also affected the red blood cell indices, and the blood monocyte and lymphocyte counts decreased suggesting immunosuppression during fasting. The results of the present study suggest that the mink has not evolved sophisticated adaptations to wintertime fasting.
Adaptation, Physiological↗
Invited review: Physiological and pathophysiological responses to intermittent hypoxia.
This mini-review summarizes the physiological adaptations to and pathophysiological consequences of intermittent hypoxia with special emphasis given to the pathophysiology associated with obstructive sleep apnea. Intermittent hypoxia is an effective stimulus for evoking the respiratory, cardiovascular, and metabolic adaptations normally associated with continuous chronic hypoxia. These adaptations are thought by some to be beneficial in that they may provide protection against disease as well as improve exercise performance in athletes. The long-term consequences of chronic intermittent hypoxia may have detrimental effects, including hypertension, cerebral and coronary vascular problems, developmental and neurocognitive deficits, and neurodegeneration due to the cumulative effects of persistent bouts of hypoxia. Emphasis is placed on reviewing the available data on intermittent hypoxia, making extensions from applicable information from acute and chronic hypoxia studies, and pointing out major gaps in information linking the genomic and cellular responses to intermittent hypoxia with physiological or pathophysiological responses.
Adaptation, Physiological↗
[Adaptation reactions in acute peritonitis and their correction using sorption detoxification].
Examined were 233 patients with acute peritonitis. In patients, who underwent the conventional intensive infusion therapy alone, in complicated course of the postoperative period, within 28 days, the high level of pathologic stress reactions was observed, which correlated with changes in the content of middle molecular mass peptides (MMMP). In uncomplicated course of the postoperative period, the MMMP level and adaptation reactions didn't differ from the control findings. Hemosorption in patients with high toxin level was accompanied by the decline in MMMP concentration below the diagnostic level, restoration of physiologic adaptation reactions.
Acute Disease↗
Neuroprotective adaptations in hibernation: therapeutic implications for ischemia-reperfusion, traumatic brain injury and neurodegenerative diseases.
Brains of hibernating mammals are protected against a variety of insults that are detrimental to humans and other nonhibernating species. Such protection is associated with a number of physiological adaptations including hypothermia, increased antioxidant defense, metabolic arrest, leukocytopenia, immunosuppression, and hypocoagulation. It is intriguing that similar manipulations provide considerable protection as experimental treatments for central nervous system injury. This review focuses on neuroprotective mechanisms employed during hibernation that may offer novel approaches in the treatment of stroke, traumatic brain injury, and neurodegenerative diseases in humans.
Adaptation, Physiological↗
Influence of a Biokinergia session on cardiorespiratory and metabolic adaptations of trained subjects.
BACKGROUND AND PURPOSE: Biokinergia (BK) is a massage aimed at improving "biological" potential. An initial pilot study demonstrated that a BK session could alter blood lactate concentration during prolonged exercise. OBJECTIVE: To confirm the effect of BK on performance and physiological adaptations during maximal aerobic muscular exercise. METHODS: Two groups of 10 subjects each performed a maximal progressive exercise on a cycle ergometer before and 10 days after a BK session (B group) or a feigned one (C group) in a simple-blinded manner. RESULTS: No modifications were noticed in the C group. After BK in the B group, maximum oxygen consumption was slightly increased (7%) and submaximal heart rate slightly lowered (4.7%) in 65% of the subjects; tidal volume was higher and breathing frequency was lower for 45% of the subjects. CONCLUSION AND DISCUSSION: The slight modifications induced by BK suggest that BK altered the sympathetic nervous system, but this needs confirmation.
Adaptation, Physiological↗
Mole-rats from higher altitudes have greater thermoregulatory capabilities.
Subterranean mammals (those that live and forage underground) inhabit a challenging microenvironment, with high levels of carbon dioxide and low levels of oxygen. Consequently, they have evolved specialised morphological and physiological adaptations. For small mammals that inhabit high altitudes, the effects of cold are compounded by low oxygen partial pressures. Hence, subterranean mammals living at high altitudes are faced with a uniquely demanding physiological environment, which presumably necessitates additional physiological adjustments. We examined the thermoregulatory capabilities of two populations of Lesotho mole-rat Cryptomys hottentotus mahali that inhabit a 'low' (1600 m) and a 'high' (3200 m) altitude. Mole-rats from the high altitude had a lower temperature of the lower critical point, a broader thermoneutral zone, a lower thermal conductance and greater regulatory non-shivering thermogenesis than animals from the lower altitude. However, minimum resting metabolic rate values were not significantly different between the populations and were low compared with allometric predictions. We suggest that thermoregulatory costs may in part be met by animals maintaining a low resting metabolic rate. High-altitude animals may adjust to their cooler, more oxygen-deficient environment by having an increased non-shivering thermogenesis whilst maintaining low thermal conductance.
Acclimatization↗