Flight muscle and heart phenotypes in the high-flying ruddy shelduck.

Ruddy shelduck migrate from wintering grounds in lowland India and Myanmar to breeding grounds in central China and Mongolia, sustaining flight over the Himalayas, where oxygen availability is greatly reduced. We compared phenotypes of the pectoralis muscle and the ventricle of the heart from ruddy shelduck and common shelduck (a closely related low-altitude congener) that were raised in common conditions at sea level, predicting that oxidative capacity would be greater in ruddy shelduck to support high-altitude migration. Fibre-type composition of the pectoralis and the maximal activity of eight enzymes involved in mitochondrial energy metabolism in the pectoralis and heart, were compared between species. Few differences distinguished ruddy shelduck from common shelduck in the flight muscle, with the exception that ruddy shelduck had higher activities of complex II and higher ratios of complex IV (cytochrome c oxidase) and complex II when expressed relative to citrate synthase activity. There were no species differences in fibre-type composition, so these changes in enzyme activity may reflect an evolved modification in the functional properties of muscle mitochondria, potentially influencing mitochondrial respiratory capacity and/or oxygen affinity. Ruddy shelduck also had higher lactate dehydrogenase activity concurrent with lower pyruvate kinase and hexokinase activity in the left ventricle, which likely reflects an increased capacity for lactate oxidation by the heart. We conclude that changes in pathways of mitochondrial energy metabolism in the muscle and heart may contribute to the ability of ruddy shelduck to fly at high altitude.

Age-related increase in mitochondrial quantity may mitigate a decline in mitochondrial quality in red blood cells from zebra finches (Taeniopygia guttata).

Aging is typically associated with a decline in whole animal performance that ultimately contributes to death. It is suspected that a decline in ATP production leads to dysfunction in cellular processes, contributing to the decline in performance. Birds require large amounts of ATP to support physiological process, especially flight, which is one of the most energetically expensive forms of locomotion in the animal kingdom to sustain. Since the bulk of ATP production is coordinated through mitochondrial activity, we set out to explore mitochondrial function in young (~8 months) and old (~73 months) zebra finches (Taeniopygia guttata). We exploited the fact that avian red blood cells (RBCs) are nucleated and have functional mitochondria to explore the phenomenon of age-related decline in mitochondrial function without the need for terminal sampling. We found that RBCs from old zebra finches have lower flux control ratios (mitochondrial O2 consumption attributed to ATP production; 0.29-0.36-fold), exhibit higher respiration (1.4-fold), and significantly higher citrate synthase activity (1.4-fold) than young birds. Respiration rates normalized to citrate synthase activity suggest that mitochondrial quality is changing, as leak state is significantly lower (0.39-fold) in old zebra finches in comparison to young animals. Overall, our findings indicate a possible change in the function of mitochondria in older zebra finches, which may be associated with a corresponding increase in mitochondrial quantity, possibly to offset a decline in mitochondrial quality.

Effects of chronic hypoxia on diaphragm function in deer mice native to high altitude.

AIM: We examined the effects of chronic hypoxia on diaphragm function in high- and low-altitude populations of Peromyscus mice. METHODS: Deer mice (P. maniculatus) native to high altitude and congeneric mice native to low altitude (P. leucopus) were born and raised in captivity to adulthood and were acclimated to normoxia or hypobaric hypoxia (12 or 9 kPa, simulating hypoxia at 4300 and 7000 m) for 6-8 weeks. We then measured indices of mitochondrial respiration capacity, force production, and fatigue resistance in the diaphragm. RESULTS: Mitochondrial respiratory capacities (assessed using permeabilized fibres with single or multiple inputs to the electron transport system), citrate synthase activity (a marker of mitochondrial volume), twitch force production, and muscle fatigue resistance increased after exposure to chronic hypoxia in both populations. These changes were not well explained by variation in the fibre-type composition of the muscle. However, there were several differences in diaphragm function in high-altitude mice compared to low-altitude mice. Exposure to a deeper level of hypoxia (9 kPa vs 12 kPa) was needed to elicit increases in mitochondrial respiration rates in highlanders. Chronic hypoxia did not increase the emission of reactive oxygen species from permeabilized fibres in highlanders, in contrast to the pronounced increases that occurred in lowlanders. In general, the diaphragm of high-altitude mice had greater capillary length densities, produced less force in response to stimulation and had shorter relaxation times. The latter was associated with higher activity of sarcoplasmic reticulum Ca2+ -ATPase (SERCA) activity in the diaphragm of high-altitude mice. CONCLUSION: Overall, our work suggests that exposure to chronic hypoxia increases the capacities for mitochondrial respiration, force production and fatigue resistance of the diaphragm. However, many of these effects are opposed by evolved changes in diaphragm function in high-altitude natives, such that highlanders in chronic hypoxia maintain similar diaphragm function to lowlanders in sea level conditions.

Use of sublingual glyceryl trinitrate as a supplement to volatile inhalational anaesthesia in a case of uterine inversion.

We present a case of uterine inversion in which glyceryl trinitrate was used via the sublingual route, as opposed to the intravenous route, in association with volatile inhalational anaesthesia in order to achieve relaxation of the uterus. A transient, but significant, hypotensive response occurred, which was easily corrected with a colloid infusion and vasopressors. Sublingual glyceryl trinitrate is easily administered, has a fast onset of action and may have a role in situations where rapid relaxation of the uterus is required.

The assessment of intramuscular discrimination using signal detection theory: its potential contribution to chiropractic.

INTRODUCTION: Most studies on sensory changes after manual therapies have focused on pain sensitivity. This ignores the wider range of sensory alternations that may be important in assessing patient functioning and neglects the issue of bias, which is inherent in most methods of pain assessment employing threshold methodology. Signal detection theory (SDT) addresses the issue of bias and provides a measurement of intramuscular discrimination--the ability to discriminate between two stimuli--which can be assessed over the full range of sensation. This paper will discuss the strengths and limitations of SDT and report on the effects of trigger point therapy and manipulation on intramuscular discrimination to illustrate the potential contribution of this methodology to chiropractic. METHODS: Intramuscular needle electrodes were used to provide a pair of electrical stimuli to the forearm extensor muscles. Subjects were asked to assess the differences between stimuli before and after treatment. The treatments consisted of manual trigger point therapy applied to the forearm extensors, cervical spine manipulation and a control treatment. RESULTS: After the trigger point therapy, there was a significant improvement in the ability of the subjects to discriminate between intramuscular signals to treated muscle. Some individual subjects showed alterations in ability to discriminate after cervical spine manipulation but the effect was not significant in the group as a whole. CONCLUSIONS: The methodology of signal detection theory provides a promising, bias-free method of assessing changes in intramuscular sensation after various treatments. In these experiments, trigger point therapy was found to enhance intramuscular discrimination, suggesting that a peripheral reflex may be involved.

Sacroiliac joint manipulation decreases the H-reflex.

Joint manipulation is widely utilized clinically to decrease pain and increase the range of motion of joints displaying limited mobility. Evidence of efficacy is based on subjective reports of symptom improvement as well as on the results of clinical trials. Experiments were designed to determine whether or not sacroiliac joint manipulation affects the amplitude of the Hoffman (H) reflex. Surface EMG recordings of the reflex response to electrical stimulation of the tibial nerve in the popliteal fossa were made from the soleus muscle. The averaged amplitudes of H-reflexes were compared on both legs before and after either sacroiliac joint manipulation or a sham procedure. H-reflex amplitude was significantly decreased (12.9%) in the ipsilateral leg (p < 0.001) following a sacroiliac joint manipulation while there was no significant alteration following the sham intervention. There was no significant alteration in reflex excitability in the contralateral leg to the sacroiliac joint manipulation. To further investigate the mechanism of these reflex alterations, the local anaesthetic cream EMLA (Astra Pharmaceuticals) was applied to the skin overlying the sacroiliac joint and the experiments were repeated on a different group of subjects. This was intended to determine if excitation of cutaneous afferents was responsible for the reflex excitability changes. There was still a significant decrease in reflex excitability (10.6%) following sacroiliac joint manipulation (p < 0.001). These findings indicate that joint manipulation exerts physiological effects on the central nervous system, probably at the segmental level. The fact that the changes persisted in the presence of cutaneous anaesthesia suggests that the reflex changes are likely to be mediated by joint and/or muscle afferents.

The effect of therapeutic muscle stretch on neural processing.

Therapeutic muscle stretch is a commonly used procedure despite little evidence in support of efficacy or information about the mechanisms underlying the various methods. The purpose of this work was to compare the sequential application of static and ballistic muscle stretch with static muscle stretch alone, using the electrically elicited Hoffmann reflex (H-reflex) as a measure of excitability of homonymous motoneurons. The foot was passively dorsiflexed and either maintained in this position or rapidly and repeatedly dorsiflexed at a velocity of 1.0 radian/sec. Hoffmann reflexes were taken using established criteria under control conditions and during stretch conditions. An analysis of variance indicated a significant difference (p < 0.05) between condition means, with H-reflex amplitude reducing to 60 and 15% of the control value during static and ballistic stretch, respectively. Since reductions in alpha-motoneuron pool excitability correlate with increased flexibility, ballistic stretch applied following static stretch appears more effective than static stretch alone.

Discriminability of electrocutaneous stimuli after topical anesthesia: detection-theory measurement of sensitivity to painful stimuli.

In three experiments on the psychophysical measurement of pain, electrocutaneous currents were applied to the volar surface of the forearm. In the first experiment, a conventional category scaling method was compared with the rating method of signal detection. The results of both methods were analyzed in detection-theory terms to derive receiver operating characteristic curves and measures of the discriminability of adjacent currents. The rating method yielded larger discriminability values than the category scale did, and that method was therefore used in the subsequent experiments to examine the effect of a topical anesthetic on discriminability. When the stimuli were applied through surface electrodes, no effect of the topical anesthetic on discriminability was found, but when the stimuli were applied to a more localized area by intradermal needle electrodes, a dose-dependent effect of the anesthetic on discriminability occurred. For this experiment, the slope of the cumulative sensitivity function increased with increasing elapsed time since the removal of the anesthetic. This result is congruent with the theory that discriminability can serve as a measure of sensitivity to painful stimuli.

Transport of latex microspheres by peripheral nerves of the rat.

The usefulness of rhodamine-labelled latex microspheres (RLM) as a marker for studying intracellular transport in peripheral nerves has been investigated in the intercostal and sciatic nerves of the rat. Suspensions of microspheres were injected into peripheral nerves, and after periods of survival ranging from 24 to 240 h, the nerves and dorsal root ganglia were fixed, frozen sections cut, and sections examined by fluorescence microscopy. It was found that RLM were transported in both anterograde and retrograde directions, but that dorsal root ganglion cells were poorly labelled. Horseradish peroxidase histochemistry did not affect the fluorescence of RLM. Features of the uptake and transport of RLM are discussed and possible applications suggested.

The behaviour of different factor VIII concentrates in a chromogenic factor X-activating system.

A chromogenic factor Xa generation method has been developed for comparing the co-factor activity of factor VIII concentrates at physiological factor VIII concentrations (1 iu/ml). In the presence of thrombin all concentrates gave similar rapid rates of factor Xa generation, but in the absence of thrombin there were major differences between the rates of Xa generation between different products. High purity products, particularly those prepared by monoclonal antibody purification from plasma and recombinant sources, gave more rapid Xa generation than most intermediate-purity products. There was a very strong correlation between the rate of Xa generation and the difference in factor VIII potency by one-stage and two-stage assays. These results suggest the possible presence of small amounts of activated factor VIII in some concentrates, but differences in von Willebrand factor content could also contribute towards the different rates of factor Xa generation observed.

Pre-spinal convergence between thoracic and visceral nerves of the rat.

Dichotomizing sensory axons have been demonstrated in a number of species and are of significance in understanding the possible mechanisms underlying referred pain. The present study reviews work employing fluorescent dyes as tracers to demonstrate afferent dichotomization in the peripheral nervous system. Dichotomization between the intercostal and splanchnic nerves of the rat was demonstrated by means of intraneural transport of Diamidino yellow or Fast blue. Frequency of pre-spinal somato-visceral convergence averaged 2% (range 0.1-21%). Average frequency of convergence was 8.3% (range 2-23.1%) between internal and external intercostal nerves. Control experiments in which axoplasmic transport was inhibited by vinblastine ruled out the possibility of errors from non-axoplasmic transport of the markers. Thoraco-visceral pre-spinal convergence occurs in the rat and is variable in extent.

Need satisfaction in terminal care settings.

Research comparing hospice and conventional programs of care for the terminally ill has identified few measurable differences in the care provided to patients and their families. Nonetheless, hospice recipients frequently express a higher level of satisfaction with their program of care. This study compared the ability of hospice and conventional care settings to meet the basic emotional needs of families during a member's dying and death from cancer. In addition, the relationship of basic needs satisfaction, perceptions about the nurse, and overall satisfaction with the program of care were explored. One hundred bereaved familial care givers completed a mail questionnaire concerning their perceptions of care at the site of a family member's death. The sites were (1) the home, with care provided by a Medicare certified, community-based hospice program: (2) a hospital affiliated with a Medicare certified, community-based hospice program; (3) a hospital with its own hospice program; and (4) a conventional (non-hospice) hospital. Analyses of quantitative data supported two hypotheses about significant differences between hospice and conventional care. The conventional care group demonstrated the lowest levels of basic needs satisfaction, satisfaction with the psycho-social support of the nurse, and overall program satisfaction. As predicted, overall satisfaction with care was consistent across hospice groups. However, home hospice care provided the highest quality of basic needs satisfaction and the highest level of satisfaction with the nurse. Significant Pearson correlations supported the hypothesis that overall satisfaction is negatively related to unmet basic needs (r = -0.69) and positively related to the psycho-social support received from nurses (r = 0.73).(ABSTRACT TRUNCATED AT 250 WORDS)

High molecular weight aggregate content of heated and unheated factor VIII products determined by fast-protein liquid chromatography.

The molecular-weight distribution of proteins in factor VIII concentrates has been analysed by fast-protein liquid chromatography. The proportion of high-molecular-weight (HMW) aggregates in one product increased on freeze-drying and heating, with fibrinogen and fibronectin being the main protein components of the HMW peak. In all other concentrates, the HMW peak was less than or equal to 5% of the total protein content and there were no differences in HMW content according to purity or method of viral inactivation.

Inhibition of interleukin-2 secretion by factor VIII concentrates: a possible cause of immunosuppression in haemophiliacs.

The inhibitory effect of factor VIII concentrate products on IL-2 secretion by human T-cells was investigated. The six products used widely in the U.K. showed very different activities varying from almost total inhibition to no significant effect. There appeared to be no obvious relationship between inhibitory activity and protein composition but factor VIII itself was not responsible for the effect as affinity purified products were entirely non-inhibitory. The two wet-heated products were most inhibitory whereas dry-heated products were less inhibitory or non-inhibitory. However, a wet-heated version of a non-inhibitory dry-heated product was also non-inhibitory, suggesting that the composition of the concentrate rather than anti-viral treatment is important for immunosuppressive activity. A product treated by the solvent/detergent procedure showed considerable inhibitory activity. Immunoglobulin and albumin products did not inhibit IL-2 secretion to any significant extent, but factor IX concentrates were inhibitory. We suggest that inhibition of IL-2 secretion by factor VIII concentrates may be related to the immunosuppression observed in haemophiliacs treated with high dose factor VIII products and that our results should be considered by clinicians and manufacturers of factor VIII products.

Assay discrepancies with highly purified factor VIII concentrates.

We have assayed two different monoclonal-antibody-purified concentrates (A and B) and one conventional concentrate (C), against the 3rd International Standard for factor VIII concentrate, using one-stage, two-stage and chromogenic methods. One-stage assays performed with immunodepleted plasmas gave lower potencies than with haemophilic plasma for all concentrates, though the discrepancies were most marked for the two highly purified products. The absence of von Willebrand factor in one of the immunodepleted plasmas appeared to contribute towards the low potencies observed. In addition, potencies of product A were 50% higher by one-stage assays (haemophilic plasma) than by two-stage or chromogenic methods. These results indicate the need for careful evaluation of assay methodologies for assessment of factor VIII:C activity in highly purified concentrates.

Effects of environmental temperature on the development of a noradrenergic thermoregulatory mechanism in the rat.

Rats reared at 30 degrees C do not exhibit the same thermoregulatory competence during cold exposure as do rats reared at 20 degrees C. They are even more clearly distinguished by the absence of an hypothermic response to intrahypothalamic noradrenaline (IH-NA). In one series of experiments, different groups of rats all received 120 days 30 degrees C-exposure and 20 days 20 degrees C-exposure. The 20 degrees C-exposure occurred at different ages in different treatment groups. At 140 days of age, bilateral IH-NA injections (each 10 micrograms/1 microliter CSF) were administered in conscious rats and the body temperature response observed. An hypothermic response to IH-NA was observed in groups whose exposure to 20 degrees C terminated between 20 and 80 days of age. In a second series of experiments, duration of rearing at 20 degrees C varied but always started at 40 days of age. Responses to IH-NA in 140-day-old adults indicated that the exposure required to induce 50% of the hypothermic response of control (20 degrees C-reared) rats was approximately 17 days. These data suggest that there is an hypothalamic noradrenergic mechanism implicated in the control of body temperature whose development is affected by environmental temperature in a duration-dependent manner. The period during which this effect may be exerted extends into adulthood.

Contralateral intramuscular acupuncture-like electrical stimulation differentially changes the short-latency responses to muscle stretch.

Measurements were made from the human first dorsal interosseous and extensor digitorum communis muscles of the surface electromyographic activity reflexly produced by brief stretch of the muscle. For the first dorsal interosseous muscle, reflex EMG activity was also produced by electrical stimulation of the ulnar nerve at the wrist. The procedures were carried out before, during, and after 25 min of nonspecific, low-frequency electrical stimulation to the contralateral arm delivered through intramuscular electrodes. Control stimulation was delivered subcutaneously. The EMG recorded during a maintained contraction was rectified, filtered, and averaged. Two reflex components (M1 and M2) of the EMG response to muscle stretch or ulnar nerve stimulation were investigated. During nonspecific intramuscular stimulation to the contralateral arm, M1 responses of the extensor digitorum communis were depressed, initially by 37%. The effect began to fade during stimulation but extended beyond it. Reflex responses were elicited alternately by brief stretch of the first dorsal interosseus muscle and by electrical stimulation of the ulnar nerve in the same experiment. Nonspecific intramuscular stimulation to the contralateral arm depressed the M1 response to stretch, but had no effect on the M1 response to electrical stimulation. It is concluded that nonspecific intramuscular electrical stimulation reduces the amplitude of the M1 component of the response to brief stretch of contralateral muscle, either through depression of fusimotor activity or inhibition of oligosynaptic pathways that contribute to the early reflex response.

Brain stem projections of the glossopharyngeal nerve and its carotid sinus branch in the rat.

Transganglionic transport of horseradish peroxidase or lectin-conjugated horseradish peroxidase from an application site in the cervical trunk of the glossopharyngeal (IXth cranial) nerve of the rat produced extraperikaryal reaction product characteristic of axon terminal processes in three regions of the brain stem: (1) the nucleus of the tractus solitarius, from approximately 2.5 mm rostral to the obex to approximately 3 mm caudal to the obex; (2) the spinal trigeminal nucleus at the level of obex; (3) the cuneate fasciculus, approximately 3 mm caudal to the obex. In contrast, labelling of the carotid sinus nerve, a branch of the glossopharyngeal nerve which conveys chemoreceptor and baroreceptor afferent fibers from the carotid bifurcation, revealed a restricted central projection to within 1 mm of the obex and corresponding to the intermediate region of the glossopharyngeal nerve projection to the nucleus of the tractus solitarius. Two distinct aggregations of label were observed: (1) rostral to the obex, within the lateral and dorsomedial subnuclei of the nucleus of the tractus solitarius; (2) caudal to the obex, within the commissural and ventrolateral subnuclei of the nucleus of the tractus solitarius. Between these two sites the density of labelling was reduced. Retrogradely labelled neurons were demonstrated in the inferior salivatory nucleus and in the nucleus ambiguus after application of lectin-conjugated horseradish peroxidase to the glossopharyngeal nerve. Of the labelled neurons in the nucleus ambiguus (approximately 100), 25% contributed fibers to the carotid sinus nerve. The concentration of extraperikaryal reaction product located rostral to the obex after labelling of the carotid sinus nerve closely matches descriptions of the region of afferent terminations from carotid and aortic baroreceptors in the cat. The concentration of label caudal to the obex may therefore correspond to the region of afferent terminations from carotid chemoreceptors. This study may therefore provide some basis for a separation of the central synapses of primary afferent fibers from the carotid baroreceptors and chemoreceptors in the rat. The labelled neurons of the nucleus ambiguus provide the anatomical substrate for centrifugal control of carotid chemoreceptor activity.

Static and dynamic response characteristics, receptive fields, and interaction with noxious input of midline medullary thermoresponsive neurons in the rat.

Thermal clamping of deep-body temperature and 16 fields covering the total truncal skin surface enabled characterization of thermal transmission neurons distributed in a midline medullary location. The total data set comprised 136 neurons from 54 female rats. Relative abundance of neuronal types was 27 to 34 to 75 for cold-responsive, warm-responsive, and thermally unresponsive neurons. Response maxima of thermoresponsive neurons to static thermal stimulation of the total truncal surface were 55 +/- 4 ips (mean +/- SE) at 5 degrees C for cold-responsive neurons and 6.0 +/- 1.6 ips at 35 degrees C for warm-responsive neurons. Dynamic thermal stimulation of the total truncal surface at rates up to +/- 1.6 degrees C/s failed to reveal a clear dynamic thermosensitivity in either cold- or warm-responsive neuronal pools. Instead, the data suggest a preferential passing of the static response relative to the dynamic response. Cutaneous thermal receptive fields were diffuse, occupying most of the truncal surface. Subparts of these fields drove thermoresponsive neurons to variable extents, suggesting convergence from unequally represented multiple cutaneous sources. Noxious stimulation at widely distributed body sites consistently augmented activity in cold-responsive neurons. A thermoregulatory rather than somatesthetic role is proposed for the midline medullary neurons studied here.