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PubMed2000

Is depression an adaptation?

Many functions have been suggested for low mood or depression, including communicating a need for help, signaling yielding in a hierarchy conflict, fostering disengagement from commitments to unreachable goals, and regulating patterns of investment. A more comprehensive evolutionary explanation may emerge from attempts to identify how the characteristics of low mood increase an organism's ability to cope with the adaptive challenges characteristic of unpropitious situations in which effort to pursue a major goal will likely result in danger, loss, bodily damage, or wasted effort. In such situations, pessimism and lack of motivation may give a fitness advantage by inhibiting certain actions, especially futile or dangerous challenges to dominant figures, actions in the absence of a crucial resource or a viable plan, efforts that would damage the body, and actions that would disrupt a currently unsatisfactory major life enterprise when it might recover or the alternative is likely to be even worse. These hypotheses are consistent with considerable evidence and suggest specific tests.

Adaptation, Physiological↗
PubMed1997

Emergency surgery for colon cancer in the aged.

BACKGROUND: The prognosis of colon cancer is poorest in cases of emergency presentation of this disease in the elderly. The high rate of clinical mortality in this group of patients has made it necessary to devise a specific therapeutic approach. OBJECTIVE: To define the therapeutic approach used for colon cancer in the elderly. DESIGN: A retrospective study. SETTING: A secondary referral center. PATIENTS: Ninety-nine patients with colon carcinoma that first became clinically manifested in an emergency situation were examined retrospectively. The patients had been treated from 1986 through 1995. All patients were older than 70 years. A total of 74 patients showed clinical manifestation of a colon carcinoma with an ileus, while 10 patients had tumor perforation. A further 15 patients had a perforation proximal to an obstructing tumor. MAIN OUTCOME MEASURES: Clinical lethality, surgical procedure, risk of comorbidity, and multiple organ system failure. RESULTS: Any increase in comorbidity was associated with a higher clinical lethality, which was especially true for the lungs, heart, and kidney, and also for diabetes. In 44.4% of the patients with a significantly higher comorbidity (P = .04) and a more advanced tumor stage (P < .001), the tumor was left in situ during the primary surgical intervention. Patients who survived after staged resection had an even higher comorbidity at first presentation when compared with patients who survived after primary resection (P = .02). However, the comorbidity of deceased patients who were supposed to undergo staged resection did not differ significantly from the comorbidity of those who underwent primary resection (P = .70). The clinical lethality in patients who were managed by stoma only or by bypass anastomosis was markedly higher than that in patients who underwent primary resection (59.0% vs 43.6%). The significantly highest postoperative mortality rate was recorded in patients who underwent primary resection after colonic perforation (74%) (P = .03), while the significantly lowest postoperative mortality rate was recorded in patients who underwent primary resection after tumor obstruction (28%) (P < .001). Postoperative failure of the lungs and heart and kidney failure requiring hemodialysis were associated with significantly higher clinical mortality rates (P < .001 to P = .004). Postoperative complications occurred in 28 (28.3%) of the patients. However, rupture of the anastomosis was observed in only 2 of these patients. Generalized disease was associated with a significantly higher rate of postoperative complications (P = .04), which was especially true for pneumonia (P = .003). However, no effect on survival was found for patients with Dukes disease stage D. CONCLUSIONS: The lower mortality rate following primary resection is achieved by preselection of patients. The preselection is such that patients in poor general condition who have tumors in advanced stages are not treated by resection. The significantly (P = .03) highest postoperative mortality rate in patients who underwent primary resection after tumor perforation reflects the necessity of resection in those cases regardless of higher comorbidity. In an emergency situation, initial minimal surgery followed by staged resection is a feasible alternative to treat aged patients with a higher comorbidity and an intraoperatively established greater spread of tumor. This procedure permits delayed radical resection at the lowest rate of clinical mortality for this age group and is especially suitable for frail, aged patients in poor condition. The advantages of staged resection can be demonstrated by the fact that more patients with a higher comorbidity survive. The poor physiological adaptability of elderly patients limits their ability to compensate for postoperative organ failure and adds the risk of comorbidity. Hence, these 2 factors are associated with poor prognosis in this age group.

Aged↗
PubMed1999

Daily energy expenditure across the course of lactation among urban Bangladeshi women.

Measures of energy intake of lactating women in developing countries show that intakes are often lower than those recommended by international bodies, while fat-mass losses are often substantially less than the 3-4 kg used in the calculations of recommendations, suggesting that physiological adaptation must be commonplace among such women. The cost of lactation may be met by reduction in energy expenditure, including reduced physical activity, as well as by mobilization of bodily soft tissue. However, daily energy expenditure of lactating women has been shown to increase across the course of lactation among women in a rural population in the Philippines and an urban population in India, with a decline in body weight across the course of lactation in both studies. In the present study, total daily energy expenditure and anthropometric body composition were measured longitudinally in 68 mothers from a poor urban area of Dhaka, Bangladesh, at 0, 1, 2, 4, and 8 months of lactation, to determine whether the increasing energy expenditure across lactation observed elsewhere also occurs in Bangladeshi women. In addition, the extent to which an extended period of lactation was accompanied by weight and body fat change in these women was determined. Energy expenditure by heart-rate monitoring and activity report, and body composition from anthropometry was carried out four times across the 8-month period of lactation. A small decline in body fat mass and a significant increase in total energy expenditure across this period were observed, confirming similar observations elsewhere in the developing world.

Adult↗
PubMed1998

Ontogenesis of the sperm whale brain.

The development of the sperm whale brain (Physeter macrocephalus) was investigated in 12 embryos and early fetuses to obtain a better understanding of the morphological and physiological adaptations in this most exotic cetacean concerning locomotion, deep diving, and orientation. In male adult sperm whales, the average absolute brain mass and the relative size of the telencephalic hemisphere are the largest within the mammalia, whereas the ratio of the brain mass to the total body mass is one of the smallest. In the early sperm whale fetus, the rostral part of the olfactory system (olfactory nerves and bulbs) is lost, whereas the nervus terminalis seems to persist. Several components of the limbic system show signs of regression (hippocampus, fornix, mamillary body). In contrast, some components of the auditory system (trapezoid body, inferior colliculus) show marked enlargement in the early fetal period, thereby reflecting their dominant position in the adult. The cerebellum and pons grow slower than in most smaller toothed whales. The pyramidal tract develops poorly (reduction of the limbs), whereas marked growth of the striatum and inferior olive may be related to the animal's locomotion via trunk and tail. In the early fetal period, the trigeminal, vestibulocochlear, and facial nerves are the dominant cranial nerves (besides the vagus nerve). Whereas the number of axons in the vestibulocochlear nerve is high in adult, toothed whales and their diameters are considerable, the trigeminal nerve of the sperm whale may be the thickest of all cranial nerves and has the largest number of axons (innervation of the huge forehead region). A similar situation seems to exist for the facial nerve: It innervates the blowhole musculature that surrounds the very large spermaceti organ and melon (generation and emission of sonar clicks).

Animals↗
PubMed1996

Insulin response in bulimia nervosa as a marker of nutritional depletion.

OBJECTIVE: The aim of this provocation study was to examine insulin, glucose, and cortisol levels in response to a glucose load in bulimia nervosa patients and to relate this to behavior, treatment status, and depressive symptomatology. METHOD: A 3-hr glucose tolerance test was performed in 15 female patients and in 4 controls. Tests were performed at different stages of treatment and following documented engagement in the patient's usual or previous repertoire of bulimic behaviors in the 24 hr prior to testing. Insulin, glucose, and cortisol levels were assayed at baseline and at 30-min intervals following the glucose load. Presence or absence of significant depressive symptomatology was ascertained. RESULTS: Three patterns of insulin response were identified: (1) an exaggerated response, (2) a normative response which resembled that of healthy controls, and (3) a blunted pattern. A reciprocal relationship between peak insulin and mean cortisol levels was seen with higher depression scores associated with blunted insulin response. Patients whose response was exaggerated binged and vomited relatively infrequently and were of stable weight. The insulin response of successfully treated patients, abstinent from binging and vomiting for 4 weeks, was similar to that of normal controls. A blunted response occurred in patients who binged and vomited more frequently, whose weight was unstable, and whose baseline eating was chaotic or nonexistent. DISCUSSION: The exaggerated insulin response was seen as a physiological adaptation to intermittent starvation reversible with treatment, while the blunted insulin response associated with higher cortisol levels was seen to result from more constant nutritional deprivation secondary to greater disturbance of behavior.

Adult↗
PubMed2001

Down-regulation in the insulin-like growth factor (IGF) axis during hibernation in the golden-mantled ground squirrel, Spermophilus lateralis: IGF-I and the IGF-binding proteins (IGFBPs).

The golden-mantled ground squirrel, Spermophilus lateralis, undergoes a profound winter hibernation that represents, among other changes, a prolonged period of starvation. In addition to dramatic metabolic and other physiological adaptations during hibernation which serve to reduce fuel energy expenditure, we have hypothesized that there may also be significant changes in the endocrine axis that regulates energetically-expensive somatic growth. As compared with euthermic, non-hibernating controls, hibernating S. lateralis were found to have 75%-reduced serum concentrations of insulin-like growth factor-I (IGF-I; from approximately 625 to approximately 150 ng/ml in both females and males, P < 0.05). While IGFBP-3 was the predominant IGFBP in serum of the euthermic controls, its levels were reduced to a similar degree in serum from the hibernating animals. IGFBP-4 was present at relatively low levels in the euthermic controls, and was reduced to undetectable levels in hibernating animals. Surprisingly, there was no IGFBP detectable in the 30 kDa range in either euthermic or hibernating S. lateralis, suggesting that IGFBP-1 does not play a role in hibernation-related changes in the IGF axis. In accordance with these endocrine changes, when serum from hibernating S. lateralis was added to cartilage explant cultures (at a 5% v/v concentration), it exhibited no ability to alter (35)S-proteoglycan synthetic rate, whereas serum from the euthermic squirrels significantly stimulated synthetic activity by 2-fold. These results suggest that part of hibernation adaptation in S. lateralis includes down-regulation in the growth-regulatory IGF axis. J. Exp. Zool. 289:66-73, 2001.

Animals↗
PubMed2000

Coping with head and neck cancer during different phases of treatment.

BACKGROUND: Little is known about how patients cope with head and neck cancer despite its devastating impact on basic functioning. This study examined coping patterns among patients at different phases of illness. METHODS: Participants were 120 patients with advanced disease, who were grouped according to the following phases of illness: (1) pretreatment, (2) on treatment, (3) <6 months after treatment, and (4) >6 months after treatment. Coping was assessed with the COPE questionnaire, and outcome measures assessed general distress (Profile of Mood States) and illness-specific distress (Impact of Events Scale). RESULTS: Use of specific coping responses differed among the groups. Denial (p <.05), behavioral disengagement (ie, giving up or withdrawing, p <.05), suppression of competing activities (ie, focusing exclusively on the illness, p <.01), and emotional ventilation (p <.10) were most characteristic of patients who were receiving or had recently completed treatment. There were no differences in flexibility of coping or overall effort expended, but patients who were on treatment or who had recently completed treatment used the greatest number of strategies. Generally, denial, behavioral disengagement, and emotional ventilation were associated with greater distress. CONCLUSIONS: Results suggest that phase of illness may be important in shaping patients' responses to life-threatening illness.

Adaptation, Physiological↗
PubMed2001

A structured review of quality of life instruments for head and neck cancer patients.

BACKGROUND: Quality of life (QOL) is an important treatment outcome for head and neck cancer. Our purpose was to critically review published disease-specific QOL instruments. METHODS: Medline and Cancerlit were searched from 1966-1999. Eight disease-specific QOL instruments were identified, described, and appraised for development, sensibility, reliability, validity and responsiveness to change. RESULTS: Several of the available instruments have been well-developed and characterized. No one instrument is ideal for all purposes. When selecting a disease-specific QOL instrument for head and neck cancer patients, careful consideration must be given to disease subsite, treatment, timing of assessment, clinical setting, study purpose and research question. CONCLUSION: Validation of QOL instruments is an ongoing process. Direct comparisons of different instruments may help to establish the most appropriate questionnaire for each situation. Efforts should be focused on the evaluation of existing instruments, rather than the development of new questionnaires.

Adaptation, Physiological↗
PubMedDate not supplied

Physical, psychological and social well-being of women with breast cancer: the influence of disease phase.

While research exists on the well-being of women during a specific phase of breast cancer, little research exists in which researchers utilized the same instruments to examine differences in women's well-being, based on the phase of their breast cancer. Using a trajectory framework, the purpose of this study is to examine the differences in the physical and social well-being of women during the following breast cancer states: newly diagnosed, adjuvant therapy, stable disease and recurrent disease. The convenience sample consisted of 35 women newly diagnosed with breast cancer, 52 women with breast cancer undergoing adjuvant therapy, 84 women whose breast cancer was considered stable and 64 women with recurrent breast cancer. Participants completed a packet of questionnaires which contained a demographic questionnaire, Short Form-36 (SF-36) Health Survey, a researcher designed (RD) questionnaire, Cancer Rehabilitation Evaluation System-Short Form (CARES-SF) and the Brief Symptom Inventory (BSI). Descriptive statistics, analysis of variance, and general linear F-tests were used to analyze the data. Differences were found across phases of disease on various subscales, including those representing perceived health states, overall impact, medical interactions, physical function, role function, fatigue, pain, social function and satisfaction with health. No significant differences were found between groups on the BSI subscales with the exception of somatization, global psychosocial measures, sexual and marital relation subscales. While individuals with recurrent disease often experienced more difficulties with their well-being than women in the other groups, women newly diagnosed and in the adjuvant group experienced more difficulties in select areas of well-being when compared with women in the stable group. Health care professionals need to recognize differences between groups to better meet the needs of patients with a breast cancer diagnosis.

Adaptation, Physiological↗
PubMed1980

Skeletal muscle fiber splitting with weight-lifting exercise in rats.

Adult male albino rats were assigned randomly to control (CON) and weight-lifting (WL) groups. The WL rats were subjected to a progressive weight-lifting program against high resistance for 8 weeks. During the last 2 weeks, each WL rat lifted a load equal to 130% of its body weight. The mean weight of the adductor longus muscle was significantly increased in the WL group ( p < 0.05). This increased muscle weight was shown to be due to an increase in the number of fibers per unit cross-sectional area ( p < 0.05), and the mean sizes of both fast-twitch oxidative glycolytic and slow-twitch oxidative fibers were significantly smaller in the WL rats than in the CON rats (p < 0.05). Light and electron microscopic examination showed that five out of eight WL rats exhibited longitudinally split muscle fibers, while only one CON rat had a few centrally placed nuclei. The splitting process appeared as either a "pinching-off" of a small segment from the parent fiber or an invagination of the sarcolemma deep into the muscle fiber in a plane parallel to the sarcomeres. There were preliminary indications that this work-induced fiber-splitting process may be a physiological adaptation of muscle to the stress of exercise.

Animals↗
PubMed1988

Structural manifestations of diabetic cardiomyopathy in the rat and its reversal by insulin treatment.

The structural effects of diabetes and subsequent insulin treatment upon the contractile and supporting elements of the rat myocardium were examined at progressive stages of both untreated and treated disease. Diabetes was induced by intravenous injection of alloxan, and tissue was examined after 6, 12, and 26 weeks. Insulin treatment began after 12 weeks of diabetes and tissue from these animals was examined after the same intervals. Within the cardiocytes, diabetes produced a focal yet progressive loss of myofibrils, transverse tubules, and sarcoplasmic reticulum, and separation of the fasciae adherens was evident at the intercalated disk. Mitochondrial damage was not evident. These cytoplasmic alterations were accompanied by intercellular and perivascular deposition of connective tissue, thickening of the endothelial cytoplasm with pinocytotic hyperactivity, and characteristic basal laminar changes. When insulin treatment began after 12 weeks of diabetes, most, but not all, of these changes were reversed, and this reversal was essentially complete within 6-12 weeks. Even with longer periods of insulin treatment, cardiocytes still exhibited scattered areas of myofibril loss and extracellular matrix was retained. In contrast, diabetic changes in the intercalated disk and capillaries, including their basal laminae, were completely and rapidly reversed. It is hypothesized that the structural manifestations of diabetic cardiomyopathy consist of two major components; the first is a short-term, physiologic adaptation to metabolic alterations, while the other represents degenerative changes for which the myocardium has only a limited capacity for repair.

Animals↗
PubMedDate not supplied

Basal metabolic rate in the Yakut (Sakha) of Siberia.

Human indigenous circumpolar populations have elevated basal metabolic rates (BMRs) relative to predicted values; this metabolic elevation has been postulated to be a physiological adaptation to chronic and severe cold stress. The present study examines BMR in the Yakut, an indigenous high-latitude population from the Sakha Republic of Russia to determine (1) whether the Yakut show evidence of an elevated BMR, (2) if the Yakut display evidence of age-related changes in BMR, and (3) whether lifestyle differences influence BMR. BMR was measured during the late summer in 75 women and 50 men (ages 18-56 years) from the Siberian village of Berdygestiakh. Measured BMR (+/- SEM) of the entire sample was significantly elevated (+6.5%) compared to predictions based on body mass (6,623.7 +/- 94.9 vs. 6,218.2 +/- 84.7 kJ/day; P < 0.001). Additionally, measured BMR for the entire sample was significantly higher than predictions based on fat-free mass (+20.8%) and surface area (+8.9%). Males and females both showed significant elevations relative to all three standards. The elevated BMR of the Yakut does not appear to be attributable to extreme levels of protein, since the Yakut consume a mixed diet with a substantial proportion of carbohydrates. No significant age-related changes in BMR were found when controlled for body composition. No significant relationship was found between lifestyle variables and BMR, suggesting the possibility of a genetic or developmental mechanism. This study provides additional evidence of metabolic elevation in indigenous circumpolar groups and has important implications for estimating the nutritional requirements of these populations.

Acclimatization↗
PubMed2004

Circadian rhythms in diet and habitat use in red ruffed lemurs (Varecia rubra) and white-fronted brown lemurs (Eulemur fulvus albifrons).

Daily variation in niche use among vertebrates is attributed to a variety of factors, including thermoregulatory, reproductive, and nutritional requirements. Lemuriform primates exhibit many behavioral and physiological adaptations related to thermoregulation and sharp, seasonal reproduction, yet they have rarely been subjects of a quantitative analysis of circadian (or daily) rhythms in niche use. In this study, I document daily rhythms in diet and microhabitat use over an annual cycle in two sympatric, frugivorous lemurs, Varecia rubra and Eulemur fulvus albifrons. Data on diet, forest site, and forest height were recorded at 5-min time points on focal animals and divided into three time blocks for analysis (06:00-10:00 hr, 10:00-14:00 hr, and 14:00-18:00 hr). I employed multivariate tests of independence to examine daily rhythms in diet and microhabitat use according to sex, season, and reproductive stage. Throughout the day, V. rubra is frugivorous and dwells in the upper canopy, with notable departures (especially for females) during the hot seasons, gestation, and lactation. E. f. albifrons has heterogeneous daily rhythms of food choice and microhabitat use, particularly across seasons, and both sexes are equally variable. These daily rhythms in diet and microhabitat use appear related to thermoregulatory and nutritional requirements, seasonal food availability and circadian rhythms of plant (and possibly insect) palatability, predator avoidance tactics, and in the case of Varecia, to reproduction. Daily rhythms of food choice in V. rubra support two previously suggested hypotheses explaining why primates consume more nonfruit items late in the day, whereas those of E. f. albifrons are too variable to lend support to these hypotheses.

Animals↗
PubMed1987

Hemoglobin concentration of pastoral nomads permanently resident at 4,850-5,450 meters in Tibet.

This paper presents data on the hemoglobin concentration of a sample of 103 pastoral nomads who are lifelong residents of Phala, at 4,850-5,450 m, on the northern plateau of the Tibet Autonomous Region of the Peoples' Republic of China. This native population resides at the highest altitude of which we are aware and is thus exposed to the most extreme chronic hypoxic stress. However, they do not exhibit the most pronounced physiological adaptations, i.e., hemoglobin concentrations exceeding those found in all other high-altitude populations. Adult male and female mean hemoglobin concentrations of 18.2 and 16.7 gm/dl, respectively, were found. These data, in conjunction with earlier studies of ethnic Tibetans living at 3,400 m, demonstrate a pattern of increasing hemoglobin concentration (erythrocytosis) at increasing altitude of residence in the Himalayas and Tibet. At the same time, however, the hemoglobin concentration is lower than that found among Andean highlanders. These new data raise the possibility of quantitative population differences in hematological adaptation to high altitude hypoxia.

Adolescent↗