Degree Of Physiological Stress Research Articles

Psychological and Physiological Effects of Low-Level Meaningful Artificial Sounds on Intellectual Tasks

AbstractThe present study aimed to investigate the psychological and physiological effects of low-level meaningful artificial sounds on intellectual tasks. The psychological factors related to the degree of disturbance, concentration, and stress, as measured by subjective evaluation, were compared with the degree of physiological stress, as measured using salivary alpha-amylase activity. The results indicated that human speech and chewing sounds caused similar levels of psychological stress while performing intellectual tasks; however, chewing sounds caused comparatively less physiological stress than did human speech sounds. These findings suggest that depending on the sound stimulus, psychological and physiological stress characteristics may not coincide.

Effect of a simulated tactical occupation task on physiological strain index, stress and inflammation

Background. This study aimed to evaluate the physiological strain index (PSI) along with specific immune system markers in response to a simulated firefighting occupation workload. Methods. Ten healthy male adults completed a 6-min simulated fire stair climb (SFSC) at 60 steps/min. The protocol consisted of four conditions, some including wearing a 34.04-kg vest to simulate personal protective equipment (PPE) and/or inclusion of a color-word interference test (CWIT) as a distracting mechanism. The PSI was evaluated by continuously monitoring the heart rate and core temperature. Salivary cortisol (CORT) was measured at baseline, mid SFSC and post SFSC. C-reactive protein (CRP) was evaluated at baseline and 1 h post SFSC. Results. Repeated-measures analysis of variance showed a significantly different PSI across conditions (p = 0.001). A significantly elevated PSI was exhibited during all 6 min of SFSC for both PPE and PPE + CWIT conditions. Neither CORT (p = 0.116) nor CRP (p = 0.700) was significantly different across conditions or from baseline. Conclusion. These findings suggest that firefighters are potentially at a substantial degree of physiological stress from exercise and the weight of gear alone. Further work should be conducted to further evaluate the usefulness of the PSI as a means to monitor firefighters during fire suppression.

The Cardiovascular Autonomic Nervous System and Anaesthesia

Once awareness, our seat of deliberate action and movement, is temporarily extinguished by sleep or a loss of consciousness, we rely on a primordial, indispensable, and autonomous (“vegetative”) system that continues to sustain and control our vital organ systems. This vegetative system is never allowed to rest. The Cambridge physiologist J N Langley referred to it as the autonomic nervous system in a paper on the superior cervical ganglion in 1898. 1 The term and concept did not receive immediate and overwhelming acceptance, but what they refer to has since been revealed as something astonishingly complex and nuanced in both its central organization, and its peripheral responses to external stimuli. Anaesthesia has as its sine qua non the reversible abolition of a patient’s so-called “nocifensive” movement response to potential, or inflicted, tissue damage. 2 This abolition, as well as the subsequent surgery it allows, is always accompanied by a degree of physiological stress that leaves the patient’s autonomic nervous system neither unprovoked nor untouched. Successful anaesthesia paradoxically both perturbs and relies on the integrity of the autonomic nervous system. Anaesthesia is autonomic medicine. The greater part of our training and practice is spent acquiring skills in averting or utilizing the autonomic nervous system effects of anaesthetic drugs or surgical procedures under a variety of pathophysiological conditions. Moreover, many of these pathophysiological conditions may be associated with impaired preoperative autonomic function. Therefore, almost every aspect of clinical anaesthesia can be discussed with some reference to the autonomic nervous system. Considerations of space preclude an exhaustive, systematic treatment of the autonomic nervous system in anaesthesia. The approach here is, firstly, to assume that the reader has a fundamental grasp of the physiology and anatomy of the cardiovascular autonomic nervous system as they relate to anaesthesia. Secondly, the extrasynaptic non-innervated hormonal receptors that mediate part of the autonomic response and that are relied on whenever inotropes are administered, are not strictly part of the autonomic nervous system and will not be elaborated on. Similarly, a description of the comparative autonomic pharmacology of the anaesthetic agents belong more appropriately in a separate monograph. Autonomic dysfunction can manifest in protean ways, and involve many organ systems, that are decisively relevant to anaesthesia. Lists, for example, of the relevant autonomic manifestations of diabetic autonomic neuropathies (Table I), of those in multiple system atrophy (MSA ‐ formerly known as Shy-Drager syndrome) (Table II), and in Parkinson’s disease (Table III) serve to illustrate this. This discussion will consider the assessment of the autonomic

Determination of kinetic changes of aggrecan-hyaluronan interactions in solution from its rheological properties

The kinetics of interactions between aggregating cartilage proteoglycan (aggrecan) and hyaluronan was examined through their rheological flow behavior using a cone on plate viscometer. The mixing of the two types of molecules was carried out directly on the plate of the viscometer, and aggregation process was monitored through the changes of the sample's steady-shear viscosity and/or dynamic shear modulus as a function of time. The effect of flow conditions on the aggrecan-hyaluronan interaction rates was examined by subjecting samples to steady-shearing motions at specified shear rates, and to oscillatory shear motions of specified frequencies and amplitudes. The characteristics of the kinetics of interaction between aggrecan and hyaluronan molecules depended not only on the flow conditions under which proteoglycan aggregation took place, but also on the concentration of the components in the solution. At high shear rates (> 10 s −1), viscosity of the mixture solution increased monotonically, starting near the viscosity of the aggrecan solution, and reaching the viscosity of the aggregate solution in approximately 35 min. Surprisingly, under slow shearing motions (< 10 s −1), the viscosities of the mixture solutions exceeded those of control aggregate solutions at identical hyaluronan: aggrecan ratios and concentrations. In addition, the aggregation under oscillatory motions took place near physiologic frequency (10 rad s −1) although the rate of aggregation process was much slower than under steady-shearing motion (> 100 min). However, the high-frequency oscillatory shearing (62.8 rad s −1) tended to impede aggregation resulting in a reduction of dynamic modulus over time. The influence of loading conditions on the rate of aggregation and aggregate size observed in this study seems to suggest a close relationship between proteoglycan structure and content, and degree of physiological stress throughout the joint and frequency of the joint motion.

Proteoglycans Nondissociatively Extracted from Different Zones of Canine Normal Articular Cartilage: Variations in the Sedimentation Profile of Aggregates with Degree of Physiological Stress

Proteoglycans were extracted and purified without dissociation (a-A1 preparations) from superficial and deeper layers of high weight-bearing (HWA) and low weight-bearing (LWA) areas of dog normal articular cartilage. These proteoglycans were then characterized by velocity gradient centrifugation. In each of the 4 different topographical regions, the weight average sedimentation coefficients related strongly with total hexuronate content of the tissue. In the superficial layers, almost all aggregates had low sedimentation coefficients: the aggregates were smaller and less abundant in LWA than in HWA. The deeper layers contained an additional population of faster sedimenting aggregates which appeared smaller and less abundant in LWA than in HWA. Quantification and functional characterization of aggregates as well as in vitro aggregating studies showed that the topographical differences in size and content of aggregates were related to differences in content of hyaluronate and link protein in the a-A1 preparations. Superficial a-A1 specimens contained twice as much hyaluronate as deeper a-A1 preparations and their hyaluronate content increased with degree of physiological stress. Deeper a-A1 specimens from weight-bearing areas did not differ in their hyaluronate content but experiments assessing the saturation with link protein of these different a-A1 preparations suggested that specimens from HWA contained more active link than those from LWA. In contrast, the capacity of aggregation of a-A1D1D1 proteoglycan monomers as well as the molecular weight (Mr = 5 x 10(5) and aggregating capacity of hyluronate molecules appeared very similar in all a-A1 preparations from areas of articular cartilage. It is hypothesized that the synthesis of the three constituents necessary for aggregate formation (i.e. proteoglycan monomers as well as hyaluronate and link protein molecules) increases with degree of physiological load and that aggregation helps to maintain within cartilage the high concentration of proteoglycans that are essential for its biomechanical functions. The reported topographical variations in the distribution of proteoglycan aggregates reflect probably a maximal adaptation of the physiologic and biomechanical properties of the matrix to meet the high stress levels experienced by the articular cartilage in vivo.