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PubMed1992

The membrane proteins of the overloaded and senescent heart.

Cardiac hypertrophy which occurs during chronic mechanical overload is one of the numerous examples of biological adaptation to environmental requirements. As such, it is obtained at random by trial and error, and adaptation represents the sum of various modifications in gene expression, including the shift in isoform of myosin or in iso Na+, K+ ATPase, the decrease in beta-adrenergic and muscarinic receptors, ryanodine channels or SR Ca2+ ATPase densities and the unchanged density in Ca2+ current. Some of these changes are beneficial at the cellular level, but are finally detrimental for the organism as a whole, as is the slowing of Vmax. It was suggested that the calcium homeostasis of the hypertrophied cardiocyte was fragile and that this modified cell was less able to buffer the changes in the intracellular calcium, thus providing a biological basis for the arrhythmogenicity of the hypertrophied heart. These various modifications may provide a new key for future pharmaceutical research.

Adaptation, Physiological↗
PubMed2001

Accelerated nervous system development contributes to behavioral efficiency in the laboratory mouse: a behavioral review and theoretical proposal.

The emergence of the laboratory mouse as a favored species for genetic research has posed a number of problems for scientists interested in the reflection of genetic influences in mouse behavior. It is commonly thought that rat behavior, which has been studied more extensively than mouse behavior, could be easily generalized to mice. In this article, a number of categories of behavior displayed by the mouse (motor, spatial, defensive, social) are reviewed and contrasted with the same categories of behavior displayed by the rat. The comparison suggests that mouse behavior is simpler and more dependent upon elementary actions than the behavior of the rat. We suggest that the behavioral simplification in the mouse adapts it for a different ecological niche than that occupied by the rat. We propose that this simplification may be mediated by accelerated brain maturation during development. We further propose that this developmental acceleration in the mouse renders it less dependent upon complex social behavior and plastic nervous system changes associated with learning than the rat. This difference poses problems for the development of relevant methods of behavioral analysis and interpretation. Since the mouse's biological adaptations will be reflected in laboratory behavior, suggestions are made for behavioral approaches to the study and interpretation of mouse behavior.

Animals↗
PubMed2000

Pinniped diving response mechanism and evolution: a window on the paradigm of comparative biochemistry and physiology.

Starting even before the end of World War II, the discipline of comparative physiology and biochemistry experienced a period of unprecedented growth and development that pioneers in this field thought would never end. However, by the mid-1970s many of the major mechanistic problems in the field were pretty well understood in principle, and by the mid-1980s workers in the field widely recognized that the discipline was at the point of diminishing returns. One response to this was disillusionment, which turned out to be premature because the field was already absorbing molecular biology tools which has now caused a kind of renaissance in mechanistic physiology studies. The second major response to the sense of disillusionment led to a search for new approaches, and out of this endeavor the newly rejuvenated field of evolutionary physiology arose, and this research area too is now in a growth phase. These general patterns of growth and development in our discipline as a whole are particularly clearly evident in the field of aquatic mammals and birds. Between the 1930s and the 1970s, studies of diving physiology and biochemistry made great progress in mechanistically explaining the basic diving response of aquatic mammals and birds. Key components of the diving response (apnea, bradycardia, peripheral vasoconstriction, redistribution of cardiac output) were found in essentially all species analyzed and were generally taken to be biological adaptations. By the mid-1970s, this approach to unraveling the diving response had run 'out of steam' and was in conceptual stasis. The breakthrough which gave renewal to the field at this time was the development of microprocessor based monitoring of diving animals in their natural environments, which led to a flurry of studies mostly confirming the essential outlines of the diving response based upon laboratory studies and firmly placing it into a proper biological context, underlining its plasticity and species specificities. Now as we begin a new millenium, despite ever more detailed field monitoring of physiology, behavior and ecology, studies aimed at improving understanding of physiological mechanisms in diving are again approaching a point of diminishing returns. To avoid another conceptual stasis, what seems required are new initiatives which may arise from two differing approaches. The first is purely experimental, relying on magnetic resonance imaging (MRI) and spectroscopy (MRS) to expand the framework of the original 'diving response' concept. The second, evolutionary study of the diving response, is synthetic, linked to both field and laboratory studies. To date the evolution of the diving response has only been analyzed in pinnipeds and from these studies two kinds of patterns have emerged. (1) Some physiological and biochemical characters, required and used in diving animals, are highly conserved not only in pinnipeds but in all vertebrates; these traits are necessarily similar in all pinnipeds and include diving apnea, bradycardia, tissue specific hypoperfusion, and hypometabolism of hypoperfused tissues. (2) Another group of functionally linked characters are more malleable and include (i) spleen mass, (ii) blood volume, and (iii) hemoglobin (Hb) pool size. Increases in any of these traits (or in a morphological character, body size) improve diving capacity. Assuming that conserved physiological function means conserved sequences in specific genes and their products (and that evolving function requires changes in such sequences), it is possible to rationalize both the above trait categories in pinniped phylogeny. However, it is more difficult for molecular evolution theory to explain how complex regulatory systems like those involved in bradycardia and peripheral vasoconstriction remain the same through phylogenetic time than it is to explain physiological change driven by directional natural selection.

Animals↗
PubMed2001

Investigations of thermal property gradients in the human dentine.

An investigation of the adaptation of dentine to temperature variation was conducted with the aid of digital moiré interferometry and thermomechanical analysis. The moiré interferometric patterns provided direct evidence of two major phases of thermally involved deformation in dentine. An initial phase of expansion was followed by contraction at higher temperatures. Significant gradients in thermal strain and the coefficient of thermal expansion were identified. Close agreement was found between the response of dentine to thermal changes as observed by moiré interferometry and that detected by thermomechanical analysis. This study highlights the biological adaptation of dentine to thermal variations.

Dentin↗
PubMed2002

Darwinian psychiatry and the concept of mental disorder.

In this paper, we discuss the concept of mental disorder from the perspective of Darwinian psychiatry. Using this perspective does not resolve all of the quandaries which philosophers of medicine face when trying to provide a general definition of disease. However, it does take an important step toward clarifying why current methods of psychiatric diagnosis are criticizable and how clinicians can improve the identification of true mental disorders. According to Darwinian psychiatry, the validity of the conventional criteria of psychiatric morbidity is dependent on their association with functional impairment. Suffering, statistical deviance, and physical lesion are frequent correlates of mental disorders but, in absence of dysfunctional consequences, none of these criteria is sufficient for considering a psychological or behavioral condition as a psychiatric disorder. The Darwinian concept of mental disorder builds from two basic ideas: (1) the capacity to achieve biological goals is the best single attribute that characterizes mental health; and (2), the assessment of functional capacities cannot be properly made without consideration of the environment in which the individual lives. These two ideas reflect a concept of mental disorder that is both functional and ecological. A correct application of evolutionary knowledge should not necessarily lead to the conclusion that therapeutic intervention should be limited to conditions that jeopardize biological adaptation. Because one of the basic aims of medicine is to alleviate human suffering, an understanding of the evolutionary foundations of the concept of mental disorder should translate into more effective ways for promoting individual and social well-being, not into the search for natural laws determining what is therapeutically right or wrong.

Biological Evolution↗
PubMed2003

Closing the loop: a spatial analysis to link observed environmental damage to predicted heavy metal emissions.

In many cases, the link between industrial emissions and damage to the environment can only be inferred. The Environment Agency of the United Kingdom imposes emissions limits on industrial sites so that predicted concentrations and deposition rates remain below standard thresholds. Estimates of appropriate critical levels and loads are usually based on laboratory results and rarely estimate synergistic effects between pollutants or consider biological adaptation or selection in the target receptor organisms. The Avonmouth smelter has been emitting zinc and other heavy metals since 1929. It has been the subject of a number of detailed and synoptic studies, especially the impact on soil invertebrates. Damage was assessed using both physiological and ecological measurements. Two methods of spatial analysis were investigated, namely interpolation using standard geographical information system (GIS) operators and atmospheric dispersal modeling using an off-the-shelf model. Both methods can be used to compute contours (isolines) of predicted biological effect. Correlation results show that dispersal modeling is at least as good as kriging but requires much less data. This article demonstrates the usefulness of GIS and dispersal models as tools in decision making to determine the most suitable sampling sites in the assessment and monitoring of the impact of contamination around major point sources.

Air Pollution↗
PubMedDate not supplied

The meaning of food in our lives: a cross-cultural perspective on eating and well-being.

Humans are biologically adapted to their ancestral food environment in which foods were dispersed and energy expenditure was required to obtain them. The modern developed world has a surplus of very accessible, inexpensive food. Amid the enormous variety of different foods are "super" foods, such as chocolate, which are particularly appealing and calorie dense. Energy output can be minimal to obtain large amounts of food. In terms of education (eg, in nutrition and risk-benefit thinking) and environment design, modern cultures have not kept pace with changes in the food world. Overweight and worrying about food result from this mismatch between human biological predispositions and the current food environment. The French have coped with this mismatch better than Americans. Although at least as healthy as Americans, they focus more on the experience of eating and less on the health effects of eating. They spend more time eating, but they eat less, partly because of smaller portion sizes. French traditions of moderation (versus American abundance), focus on quality (versus quantity), and emphasis on the joys of the moment (rather than making life comfortable and easy) support a healthier lifestyle. The French physical environment encourages slow, moderate social eating, minimal snacking, and more physical activity in daily life.

Cross-Cultural Comparison↗
PubMed2005

Spatial mosaic formation through frequency-dependent selection in Müllerian mimicry complexes.

Although contemporary models of Müllerian mimicry have considered the movement of interfacial boundaries between two distinct mimetic forms, and even the possibility of polymorphisms in two patch systems, no model has considered how multiple forms of Müllerian mimics might evolve and be maintained over large geographical areas. A spatially explicit individual-based model for the evolution of Müllerian mimicry is presented, in which two unpalatable species are distributed over discrete cells within a regular lattice. Populations in each cell are capable of genetic drift and experience localized dispersal as well as frequency-dependent selection by predators. When each unpalatable prey species was introduced into a random cell and allowed to spread, then mimicry evolved throughout the system in the form of a spatial mosaic of phenotypes, separated by narrow "hybrid zones". The primary mechanism generating phenotypic diversity was the occasional establishment of new mutant forms in unoccupied cells and their subsequent maintenance (and spread) through frequency-dependent selection. The mean number of discrete clusters of the same morph that formed in the lattice was higher the higher the intensity of predation, and higher the lower the dispersal rate of unpalatable prey. Under certain conditions the hybrid zones moved, in a direction dependent on the curvature of their interfacial boundaries. However, the mimetic mosaics were highly stable when the intensity of predation was high and the rate of prey dispersal was low. Overall, this model highlights how a stable mosaic of different mimetic forms can evolve from a range of starting conditions through a combination of chance effects and localized frequency-dependent selection.

Adaptation, Biological↗
PubMed1999

The origins of insect metamorphosis.

Insect metamorphosis is a fascinating and highly successful biological adaptation, but there is much uncertainty as to how it evolved. Ancestral insect species did not undergo metamorphosis and there are still some existing species that lack metamorphosis or undergo only partial metamorphosis. Based on endocrine studies and morphological comparisons of the development of insect species with and without metamorphosis, a novel hypothesis for the evolution of metamorphosis is proposed. Changes in the endocrinology of development are central to this hypothesis. The three stages of the ancestral insect species-pronymph, nymph and adult-are proposed to be equivalent to the larva, pupa and adult stages of insects with complete metamorphosis. This proposal has general implications for insect developmental biology.

Animals↗
PubMed1984

Searching-waiting strategy: a candidate for an evolutionary model of depression?

The model proposed here assumes that depressive disorders could reflect an extreme state of a current behavioral strategy. According to this model, a subject facing a problem of survival without apparent solution may choose between two behavioral patterns: searching for a solution or waiting for that solution to occur. This choice can be made after one or several estimations of the cost and benefit attached to each of these alternatives. Two of the main behavioral models of depression are interpreted according to this model: namely, infant response to maternal separation in monkeys and "behavioral despair" in rodents. Practical and theoretical consequences of this model are discussed.

Adaptation, Biological↗
PubMed1996

Hypothalamic cellular and molecular mechanisms helping to satisfy axiomatic requirements for reproduction.

In the absence of universal equations expressing neurobiological findings, the safest theoretical approach for the neuroendocrinologist is to start from axiomatic requirements for biologically adaptive neural mechanisms, in our case for reproduction. From this emerge two themes: the likely importance of interactions between internal (hormonal) and external signals in controlling gene expression relevant to reproductive functions; and, second, the vision of molecular interactions on DNA subserving environmental impacts on reproduction. The first theoretical notion has so far yielded data showing a role for synaptic inputs during the onset of estradiol actions for the hormone's induction of enkephalin mRNA, a finding which parallels earlier behavioral results. As well, noxious somatosensory inputs interact with estrogens and progesterone in their influence on enkephalin gene expression. The second theme led to novel investigations of thyroid influences on reproductive molecular biology and behavior, including the ability of exogenous or endogenous thyroid hormones to reduce female mating responses. Since elevated thyroid hormone levels could signal environmental cold, our experiments offer the possibility of explaining ethological facts at a molecular level. More generally, nuclear hormone receptor interactions on the surface of DNA may offer a new level of neural integration revealed first by hormone effects in neuroendocrine cells.

Animals↗
PubMed1982

Agonistic behaviour in rats: evidence for non-involvement of opioid mechanisms.

It has recently been proposed that a stress-activated, endogenous analgesia mechanism would be adaptive in situations in which pain perception might otherwise disrupt effective behavioural performance. In a semi-natural test situation, the current study examined two predictions arising from this hypothesis: (1) in a manner analogous to other stressors, agonistic experience should produce analgesia and, if naloxone-sensitive opioid mechanisms are implicated, then (2) pretreatment with naloxone should block the development of this response and alter the displayed behaviour patterns. Neither prediction was substantiated by the data. Experience of an agonistic encounter failed to produce analgesia in either resident or intruder animals. Furthermore, naloxone hydrochloride (1-25 mg/kg) was also without effect on patterns of offense or defense. Data are discussed in relation to the critical nature of the stimulus factors involved in the activation of endogenous analgesic mechanisms and the postulated involvement of such mechanisms in biologically-adaptive behaviours.

Aggression↗
PubMed2003

Effects of Ginkgo biloba on corticosterone stress responses after inescapable shock exposure in the rat.

Extracts from the leaves of the Ginkgo biloba tree (GBE) are found to be clinically effective in neuroprotection, cerebral and cardiovascular function and cognitive processing. Recent animal findings suggest that GBE also may improve stress adaptation and prevent learned helplessness, as evidenced by its reduction of behavioral acquisition deficits of active avoidance after inescapable shock exposure. In the present report, the effects of two doses of GBE were studied on corticosterone stress responses and acquisition of active avoidance after inescapable shock exposure. Forty-eight rats were divided into three groups: either receiving a daily dose of 50 mg/kg or 150 mg/kg of GBE (containing 24% flavonoid and 6% terpenoid) or vehicle for 2 weeks. After 2 weeks of administration, animals were trained for active-avoidance acquisition following inescapable shock exposure (stress induction) or nonshock exposure (nonstress). Administration of 150 mg/kg but not of 50 mg/kg of GBE significantly prevented a corticosterone stress response after inescapable shock exposure (P<.0001) without any beneficial behavioral effect on active avoidance. Repeated administration of GBE particularly improves biological adaptation to noxious stimuli without beneficial behavioral consequences. Present findings do not support previous claims about the benefits of G. biloba on improving behavioral stress adaptation and acquisition of active avoidance and on reducing behavioral deficits indicative of "learned helplessness."

Animals↗
PubMedDate not supplied

Reproductive success: which meaning?

The theory of kin selection (the part played by behavior in the changes of mean inclusive fitness) induced many human sociobiologists to think that since behavior was involved in the increase in fitness, this last entity could apply to the individual. Approximated by the individual's lifetime reproductive success, this measure became the keyword of studies linking social and cultural behavior to biological adaptive processes. To be commonly applicable to human populations, it had to be simplified to represent the number of offspring reaching sexual maturity and most existing studies are based on this definition. The current trend, however, seems to consider that, like inbreeding, reproductive success takes its signification in the depth of successive generations. These diverse measures were tested in two traditional populations, Berber and Aymara, and show that finding a satisfactory evaluation of reproductive success is a problem that is still far from a solution.

Family Characteristics↗
PubMed1995

[Importance of DSM IV (APA) and ICD-10 (WHO) in diagnosis and treatment of mood disorders].

Since 1993, with ICD-10 (WHO), and 1994, with DSM IV (APA), practitioners have had at their disposal two (practically compatible) classifications of mental disorders containing operational criteria for diagnosis, and helpful in guiding clinical and therapeutic approach. Moreover, the use of one of these classifications (ICD-10) is compulsory in French state psychiatric institutions. We shall try to convince that these manuals are useful, and indeed unavoidable, henceforth, not only for researchers but also for practitioners, for the following reasons: "Any form of order is preferable to chaos" (Lévi Strauss); An implicit classification is always at work, even where the clinician feels he is working by intuition and treating each patient as a unique and individual case. It is not necessarily a bad thing to compare one's own stereotypes with currently held beliefs; All efforts to evaluate treatments, both psychotherapeutic and chemotherapeutic, are now based on these clinical definitions and models. Particularly as regards mood disorders, DSM III and DMS IV have managed to rid us of the uncertainties and contradictions surrounding etiopathogenesis (endogenous? psychogenic? reactive? defensive? adaptive? biological? etc.) which previously ruled out any explanatory classification. There still remain a number of pathological pictures of proven existence but with different levels of significance and different treatments. The bipolar/unipolar distinction (BP/UP) has been strengthened. Major depression (actual "depression", of moderate severity) remains the central model, and exists in both the unipolar and bipolar forms. There is also chronic (more than 2 years) progressive dysthymia (UP) which corresponds almost exactly to "Depressive personality". For bipolar disorders, the distinction between bipolar I disorders and bipolar II disorders, which is now well-documented, has been retained. Cyclothymia (lasting over 2 years) is in a sense the bipolar equivalent of dysthymia. Mixed disorders are distinguished from rapid-cycling bipolar disorders. It is now known that the range of bipolar disorders requires treatment with thymoleptic drugs and that antidepressants should be used only in unipolar disorders, and occasionally in bipolar forms to treat certain acute episodes of depression. Furthermore, many specific clinical forms are defined: postnatal depression, seasonal depression, adaptive difficulties with depressive mood or anxiety and depression, iatrogenic depression or depression related to medication or to intercurrent illnesses. Moreover, criteria are also suggested "for future studies" of post-psychotic depression in schizophrenic patients, minor depression, brief recurrent depressive episodes and anxio-depressive syndrome.

Antidepressive Agents↗
PubMed1979

[The serum concentration of anticonvulsants -- pharmacokinetic findings and practical therapeutic applications (author's transl)].

Routine determination of the blood serum concentration of most of the usual anticonvulsants is possible by means of an immunoenzymatic method (EMIT). Determination of the total concentration permits conclusions as to the amount of available, unbound and, thus, effective amount of the substance. Regular determination of serum values provides insight into the relevant pharmacokinetics. Metabolism of anticonvulsants differs greatly among individuals and therefore considerable individual variation exists in the relation between the applied dose and the attained serum level. The metabolic rate of the various substances is unequal and, accordingly, the time necessary to reach a steady state and the half life is very variable. Metabolism may be altered by various biological adaptations, diseases or other drugs, causing alterations in the serum level of the anticonvulsant. Results obtained to date indicate a therapeutic threshold concentration range. In a certain percentage of patients seizures are abolished or diminish in frequency only on attaining such a serum level. In more benign cases an adequate therapeutic effect may be obtained with lower ("subtherapeutic") concentrations, while on the other hand, in malignant cases, no efficient control of seizure activity can be attained even at a high serum concentration. The method should be used in all problematic patients. Up to 50% of patients with insufficient control of seizures show improvement or, even, absence of seizures if this method is included in the therapeutic concept.

Antacids↗
PubMed2005

Shooting darts: co-evolution and counter-adaptation in hermaphroditic snails.

BACKGROUND: Evolutionary conflicts of interest between the sexes often lead to co-evolutionary arms races consisting of repeated arisal of traits advantageous for one sex but harmful to the other sex, and counter-adaptations by the latter. In hermaphrodites, these antagonistic interactions are at least an equally important driving force. Here, we investigate the evolution of one of the most striking examples of sexual conflict in hermaphrodites, the so-called shooting of love-darts in land snails. Stabbing this calcareous dart through the partner's skin ultimately increases paternity. This trait is obviously beneficial for the shooter, but it manipulates sperm storage in the receiver. Hence, an arms race between the love-dart and the spermatophore receiving organs may be expected. RESULTS: We performed a detailed phylogenetic analysis of 28S ribosomal RNA gene sequences from dart-possessing land snail species. Both the Shimodaira-Hasegawa test and Bayesian posterior probabilities rejected a monophyletic origin of most reproductive structures, including the love-dart, indicating that most traits arose repeatedly. Based on the inferred phylogenetic trees, we calculated phylogenetically independent contrasts for the different reproductive traits. Subsequent principal component and correlation analyses demonstrated that these contrasts covary, meaning that correlated evolution of these traits occurred. CONCLUSION: Our study represents the first comprehensive comparative analysis of reproductive organ characteristics in simultaneous hermaphrodites. Moreover, it strongly suggests that co-evolutionary arms races can result from sexual conflict in these organisms and play a key role in the evolution of hermaphroditic mating systems.

Adaptation, Biological↗