Synchronism in a metapopulation model

We consider a spatially explicit metapopulation model with interaction among the two nearest neighbors to relate, with a simple mathematical expression, chaos in the local, uncoupled, populations, the degree of interaction among patches, size of the metapopulation, and the stability of the synchronized attractor. Since synchronism is strongly correlated with extinction, our results can provide useful information on factors leading to population extinction.     

Cardiorespiratory function

ACCURATE EVALUATION OF THE DEGREE OF IMPAIRMENT OF PULMONARY FUNCTION IN PERSONS WITH FIBROSIS AND EMPHYSEMA REQUIRES: (1) ventilatory measurements from rapid spirogram tracings (vital capacity, maximal breathing capacity and the time required to blow the air from the lungs); (2) determination of the degree of bronchospasm present; (3) determination of the degree of pulmonary emphysema (residual air expressed quantitatively as percent of total lung volume); (4) determination of the arterial blood oxygen saturation at rest and immediately after step-up exercise; (5) measurement of the oxygen extraction from inspired air (per cent of oxygen removed) during rest and exercise; (6) determination of the oxygen up-take during exercise; and (7) observation of the duration of dyspnea after step-up exercise. No single physiologic test is adequate in evaluating impairment of pulmonary function, and roentgenograms of the chest are unreliable as a sole basis for appraisal of disability. In industrial medicine, pulmonary function studies make possible (a) more accurate diagnosis and evaluation of pulmonary disability; and (b) earlier detection and thus prevention of prolonged exposure by susceptible individuals to environmental hazards.     

Cardiorespiratory Coordination in Acute Hypoxia in Runners

Human Physiology - The study was aimed at determining cardiorespiratory coordination under the influence of acute hypoxia in athletes with different levels of sports qualifications. Eighteen...     

Adult Neurogenesis in Humans

Adult neurogenesis appears very well conserved among mammals. It was, however, not until recently that quantitative data on the extent of this process became available in humans, largely because of methodological challenges to study this process in man. There is substantial hippocampal neurogenesis in adult humans, but humans appear unique among mammals in that there is no detectable olfactory bulb neurogenesis but continuous addition of new neurons in the striatum.There has been an enormous expansion in the knowledge regarding adult neurogenesis in experimental animals over the last two decades. A strong motivation in this research field has been that similar processes are likely to operate in humans, and that alterations in adult neurogenesis could underlie neurological or psychiatric diseases. Moreover, many have hoped that the potential of resident neural stem cells could be harnessed to promote the generation of new neurons for cell replacement in neurological diseases. A seminal study by Eriksson, Gage and colleagues (Eriksson et al. 1998), in which they were able to show the presence of 5-bromo-2-deoxyuridine (BrdU) in hippocampal neurons of cancer patients who had received the label for diagnostic purposes, established the presence of adult-born neurons in the human hippocampus. This study was exceptionally important in that it provided strong evidence for the presence of adult neurogenesis in humans. However, it did not enable any quantitative estimates, and a lingering question has been whether adult neurogenesis decreased with primate evolution, and whether the extent of this process in humans is sufficient to have any functional impact (Rakic 1985; Kempermann 2012).     

Cardiorespiratory interactions to external stimuli

Respiration is a powerful modulator of heart rate variability, and of baro- or chemo-reflex sensitivity. This occurs via a mechanical effect of breathing that synchronizes all cardiovascular variables at the respiratory rhythm, particularly when this occurs at a particular slow rate coincident with the Mayer waves in arterial pressure (approximately 6 cycles/min). Recitation of the rosary prayer (or of most mantras), induces a marked enhancement of these slow rhythms, whereas random verbalization or random breathing does not. This phenomenon in turn increases baroreflex sensitivity and reduces chemoreflex sensitivity, leading to increases in parasympathetic and reductions in sympathetic activity. The opposite can be seen during either verbalization or mental stress tests. Qualitatively similar effects can be obtained even by passive listening to more or less rhythmic auditory stimuli, such as music, and the speed of the rhythm (rather than the style) appears to be one of the main determinants of the cardiovascular and respiratory responses. These findings have clinical relevance. Appropriate modulation of breathing, can improve/restore autonomic control of cardiovascular and respiratory systems in relevant diseases such as hypertension and heart failure, and might therefore help improving exercise tolerance, quality of life, and ultimately, survival.     

Cardiorespiratory Studies in Patients with Pulmonary Tuberculosis

Cardiorespiratory studies in 13 young females and 11 middle-aged men with localized acute pulmonary tuberculosis revealed evidence of significant resting hyperventilation and reduction in the dynamics of ventilation indicative of restrictive lung disease. Indices of intrapulmonary mixing and pulmonary diffusing capacities were normal, as were alveolar-arterial pCO₂ gradients.The ventilation/perfusion ratios were slightly elevated in both groups, while pulmonary artery pressure and total pulmonary vascular resistance (TPVR) showed a rise in the males only.Both groups showed an increase in actual QBF flows and a resultant significant decrease in arterial pO₂, which suggests that the areas of tuberculous infection are metabolically active.     

Cardiorespiratory effects of nifedipine in pregnant sheep

Four concentrations of nifedipine (AdalatR, Bayer) were infused into 25 pregnant sheep of 123-140 days of gestation (term, 147 days) and the effects on the ewe and the foetus have been studied. At all doses of nifedipine infused, maternal diastolic pressure fell by about 15% and maternal heart rate increased by 33%. There was no change in blood gases or pH. Uterine activity, as measured by uterine electromyographic recordings, was reduced due to an increase in the interval between periods of activity. The duration of a burst of activity remained unaffected. The effects of nifedipine on the foetus, were similar. Mean foetal arterial pressure fell by 4-5 mmHg and heart rate rose by 15 to 50%, both changes being maintained for the duration of the infusion and the increased heart rate for longer. The electrocorticogram of the foetal sheep was unaffected by nifedipine. The effects on foetal breathing movements were small. At the concentration of 5 micrograms/kg/min for either 2 or 4 hours the breathing pattern changed so that the episodes of breathing were shorter and more frequent. The total amount of breathing per hour was unaffected. Control infusion of ethanol had little effect on the ewe except for a significant increase in lactate production. In the foetus breathing was reduced at the highest concentration used.     

Identifying and Evaluating Patterns in Cardiorespiratory Physiology

SYNOPSIS. A major theme of many papers in this symposium isthe identification of broad physiological trends and patternsthat extend beyond the boundaries of data from individual studies.Recognizing patterns in everything from hypoxic ventilatorypatterns to regulation of blood gases not only helps the investigatorunderstand specific data sets, but also helps place those datain a broad context. Yet, recognizing physiological patternsis confounded by two factors: phylogenetic relationships andphysiological state. Fortunately, the last decade has seen infiltrationof sound evolutionary theory, including tools of cladisiticanalysis and population genetics, into more and more studiesof comparative physiology. However, even when an experimentercarefully accounts for phytogeny, differences in physiologicalstate in the experimental animals can still obscure physiologicalpatterns. Two informal categories of physiological state aredescribed, the first obvious and frequently controlled for,and the second less obvious and typically not controlled for.Examples of the latter, including seasons, rhythms, prandialeffects and sex of the animal, are developed to show how ignoringthese can lead to considerable misleading variation in cardiorespiratorydata sets. Considering physiological state is vital in producingreliable data that can be used meaningfully for delineatingbroad physiological patterns.     

Aberrant Gene Expression in Humans

Gene expression as an intermediate molecular phenotype has been a focus of research interest. In particular, studies of expression quantitative trait loci (eQTL) have offered promise for understanding gene regulation through the discovery of genetic variants that explain variation in gene expression levels. Existing eQTL methods are designed for assessing the effects of common variants, but not rare variants. Here, we address the problem by establishing a novel analytical framework for evaluating the effects of rare or private variants on gene expression. Our method starts from the identification of outlier individuals that show markedly different gene expression from the majority of a population, and then reveals the contributions of private SNPs to the aberrant gene expression in these outliers. Using population-scale mRNA sequencing data, we identify outlier individuals using a multivariate approach. We find that outlier individuals are more readily detected with respect to gene sets that include genes involved in cellular regulation and signal transduction, and less likely to be detected with respect to the gene sets with genes involved in metabolic pathways and other fundamental molecular functions. Analysis of polymorphic data suggests that private SNPs of outlier individuals are enriched in the enhancer and promoter regions of corresponding aberrantly-expressed genes, suggesting a specific regulatory role of private SNPs, while the commonly-occurring regulatory genetic variants (i.e., eQTL SNPs) show little evidence of involvement. Additional data suggest that non-genetic factors may also underlie aberrant gene expression. Taken together, our findings advance a novel viewpoint relevant to situations wherein common eQTLs fail to predict gene expression when heritable, rare inter-individual variation exists. The analytical framework we describe, taking into consideration the reality of differential phenotypic robustness, may be valuable for investigating complex traits and conditions.     

Pasteurella Septica Infections in Humans

Five instances of infection by Pasteurella septica, an organism which closely resembles H. influenzae on methods of presumptive bacteriology, are reported from an acute treatment general hospital practice over a period of three months. This infection decidedly outnumbers those caused by other Pasteurella species in North America. The organism is apt to be identified as H. influenzae, Friedlander''s bacillus or Mima polymorpha. Unlike these, it shows extreme sensitivity to penicillin, sometimes combined with resistance to antibiotics that inhibit or kill these other organisms.While in the past Pasteurella septica infection was considered to be characterized by persistent local infection following domestic animal scratches or bites, it is clear that it is more often found in cases of respiratory tract infection and peripheral septic disease. In three of the five cases reported, exposure to animals was the source of infection.Because mixed infection with confusingly similar organisms may occur, lack of awareness of extreme penicillin sensitivity of Pasteurella septica may account for persistent failure of antibiotic therapy.     

Mate Choice Copying in Humans

There is substantial evidence that in human mate choice, females directly select males based on male display of both physical and behavioral traits. In non-humans, there is additionally a growing literature on indirect mate choice, such as choice through observing and subsequently copying the mating preferences of conspecifics (mate choice copying). Given that humans are a social species with a high degree of sharing information, long-term pair bonds, and high parental care, it is likely that human females could avoid substantial costs associated with directly searching for information about potential males by mate choice copying. The present study was a test of whether women perceived men to be more attractive when men were presented with a female date or consort than when they were presented alone, and whether the physical attractiveness of the female consort affected women’s copying decisions. The results suggested that women’s mate choice decision rule is to copy only if a man’s female consort is physically attractive. Further analyses implied that copying may be a conditional female mating tactic aimed at solving the problem of informational constraints on assessing male suitability for long-term sexual relationships, and that lack of mate choice experience, measured as reported lifetime number of sex partners, is also an important determinant of copying.