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At least 487 records · Page 27Linked to original sources
PubMed2006

Hereditary angioedema associated with heterozygous factor V Leiden mutation in a patient with Purpura fulminans.

BACKGROUND: Hereditary angioedema (HAE) is an autosomal dominant, quantitative or functional defect of the C1 esterase inhibitor. The main role of the C1 esterase inhibitor is to regulate the activation of the complement system, the contact phase of the intrinsic coagulation system. On the other hand, factor V Leiden is the most common cause of primary and recurrent venous thromboembolism and displays a strong interaction with oral contraceptives. Here we report the case of a patient with HAE associated with the factor V Leiden mutation who had purpura fulminans when put on an oral contraceptive therapy. CASE: A 42-year-old woman presented to the emergency room with a history of livid skin changes on her legs during a flight. On physical examination, the vital signs were normal, but there were edemas in her legs. The livid skin changes tended to increase, eventually leading to skin necrosis on the next day. She had a history of a similar episode two months before and experienced both episodes of necrotic skin lesions just after she had been put on a hormone replacement therapy due to irregular menstruations. She also had a history of recurrent angioedema attacks since her childhood, triggered by stress and physical stimulants such as pressure and heat. Subsequent investigations revealed heterozygous factor V mutation, activated protein C resistance and reduced C1 inhibitor levels. CONCLUSION: Thrombosis is a multifactorial disease. The coexistence of multiple hereditary and acquired factors eases its occurrence. Women with HAE should be screened for the factor V Leiden mutation before pregnancy or the start of a hormone replacement therapy.

Adult↗
PubMed1978

Relationship between tachycardia, prolactin and growth hormone in conscious ewes.

Brief episodes of apparently unprovoked tachycardia (increased heart rate, HR) lasting about 10--20 min were observed about one h after initiation of experimentation in 10 ovariectomized ewes which were fitted with indwelling vascular cannulae. The incidence of tachycardia episodes varied among ewes, but 99 of 215 (46%) sampling trials contained such an episode (mean HR increase = 34 beats/min). Approximately 30--40 min after maximum tachycardia when HR had returned to basal rates, both plasma prolactin (Prl) and growth hormone (GH) increased significantly from the nadir concentrations that had been observed around the time of maximum tachycardia and shortly thereafter. There were no changes in packed cell volume (PCV) and only brief changes in mean arterial blood pressure related to the tachycardia. There was a mild trembling behavior associated with many of the tachycardia episodes. The causes for the tachycardia are not known. Heparin administration did not seem to be involved, but physical stimulation inside the jugular vein, while not essential, may increase the incidence of tachycardia episodes.

Animals↗
PubMed1981

Amygdalectomy Inhibits adrenocortical responses to somatosensory and olfactory stimulation.

Adrenocortical responses, as measured by plasma corticosterone, to ether stress, photic, acoustic, sciatic and olfactory stimulation, were studied in amygdalectomized and in intact rats. While amygdalectomy had no effect on the adrenocortical responses following ether stress or photic and acoustic stimulation, the responses following sciatic and olfactory stimulation were markedly reduced. These results, taken together with our previous studies, suggest that the amygdala participates in the transmission of adrenocortical responses to olfactory stimulation and has also a modulatory facilitatory effect on the adrenocortical response to somatosensory stimulation. Amygdalectomy also reduced the effect of dexamethasone on basal plasma corticosterone secretion, indicating that the amygdala may participate in the feedback regulation of pituitary-adrenal function.

Acoustic Stimulation↗
PubMed1976

Visual and nonvisual units recorded from the optic tectum of Gallus domesticus.

Units recorded from the optic tectum of Gallus domesticus were tested for responses to visual, auditory and somesthetic and stimuli. Units recorded from the superficial tectal layers (stratum opticum, stratum griseum et fibrosum superficiale) responded only to visual stimuli. On the basis of the unit's responsiveness to the directionality of a moving visual stimulus, three unit types referred to as pandirectional, unidirectional, and multidirectional units were identified. In the deeper layers (stratum griseum centrale, stratum album centrale) unimodal and bimodal units were encountered. These units responded to visual, auditory, and/or somesthetic stimuli. These results indicate that the tectal cortex of Gallus domesticus is subdivided into two functional divisions: the superficial layers which correlate visual information and the deep layers which correlate visual and nonvisual information.

Acoustic Stimulation↗
PubMed1992

Digital speech processing for cochlear implants.

A rather general basic working hypothesis for cochlear implant research might be formulated as follows. Signal processing for cochlear implants should carefully select a subset of the total information contained in the sound signal and transform these elements into those physical stimulation parameters which can generate distinctive perceptions for the listener. Several new digital processing strategies have thus been implemented on a laboratory cochlear implant speech processor for the Nucleus 22-electrode system. One of the approaches (PES, pitch excited sampler) is based on the maximum peak channel vocoder concept whereby the spectral energy of a number of frequency bands is transformed into appropriate electrical stimulation parameters for up to 22 electrodes using a voice pitch synchronous pulse rate at any electrode. Another approach (CIS, continuous interleaved sampler) uses a maximally high pitch-independent stimulation pulse rate on a selected number of electrodes. As only one electrode can be stimulated at any instance of time, the rate of stimulation is limited by the required stimulus pulse widths (as determined individually for each subject) and some additional constraints and parameters which have to be optimized and fine tuned by psychophysical measurements. Evaluation experiments with 5 cochlear implant users resulted in significantly improved performance in consonant identification tests with the new processing strategies as compared with the subjects own wearable speech processors whereas improvements in vowel identification tasks were rarely observed. The pitch-synchronous coding (PES) resulted in worse performance compared to the coding without explicit pitch extraction (CIS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1996

Hypochondriasis and symptom reporting--the effect of attention versus distraction.

BACKGROUND: This study examined symptom perception in hypochondriacal patients without physical stimulation. METHODS: Seventeen outpatients with DSM-III-R hypochondriasis and 16 healthy control subjects were compared. All subjects were asked to report perceived sensations in three conditions: attention, distraction and control. RESULTS: It was found that hypochondriacal subjects showed remarkably higher levels of symptom reporting than healthy subjects in all three conditions. In spite of excessive attention to bodily sensations in a control condition, attention instructions still added significantly to symptom reporting in hypochondriacal patients. The effect of distraction was not significant in either of the groups. Furthermore, group differences in symptom reporting appeared to be related to preoccupation with bodily symptoms rather than to general anxiety level as measured by the STAI. CONCLUSIONS: Hypochondriacal patients report more bodily sensations than healthy controls when no instructions are given. In addition, focussing on bodily sensations seems to cause a significant overall increase of perceived symptoms in hypochondriacal patients, whereas in healthy subjects there is a trend towards an increase in symptom reporting.

Adult↗
PubMed1977

The role of the QT interval in the sudden infant death syndrome.

To evaluate the role of QT interval prolongation in the genesis of the sudden infant death syndrome (SIDS), the post-resuscitation electrocardiograms of 21 aborted SIDS infants were reviewed. The infants had been found apneic, cyanotic, limp and unresponsive during sleep and required vigorous physical stimulation and mouth-to-mouth resuscitation. Three subsequently experienced repeat similar episodes from which they could not be resuscitated. Extensive studies eliminated all "known" etiologies for death. The QT intervals of these infants were compared to age and sex matched normal infants as well as to established normal values in the literature; in both the aborted and the subsequent actual SIDS infants, the QT intervals were not significantly different from those of the normal population. Thus, we conclude that QT intervals prolongation does not play a major role in the genesis of the aborted SIDS.

Electrocardiography↗
PubMed2002

Supramodal effects of covert spatial orienting triggered by visual or tactile events.

Event-related functional magnetic resonance imaging was used to identify brain areas involved in spatial attention and determine whether these operate unimodally or supramodally for vision and touch. On a trial-by-trial basis, a symbolic auditory cue indicated the most likely side for the subsequent target, thus directing covert attention to one side. A subsequent target appeared in vision or touch on the cued or uncued side. Invalidly cued trials (as compared with valid trials) activated the temporo-parietal junction and regions of inferior frontal cortex, regardless of target modality. These brain areas have been associated with multimodal spatial coding in physiological studies of the monkey brain and were linked to a change in the location that must be attended to in the present study. The intraparietal sulcus and superior frontal cortex were also activated in our task, again, regardless of target modality, but did not show any specificity for invalidly cued trials. These results identify a supramodal network for spatial attention and reveal differential activity for inferior circuits involving the temporo-parietal junction and inferior frontal cortex (specific to invalid trials) versus more superior intraparietal-frontal circuits (common to valid and invalid trials).

Adult↗
PubMed2006

Dynamic gain changes during attentional modulation.

Attention causes a multiplicative effect on firing rates of cortical neurons without affecting their selectivity (Motter, 1993; McAdams & Maunsell, 1999a) or the relationship between the spike count mean and variance (McAdams & Maunsell, 1999b). We analyzed attentional modulation of the firing rates of 144 neurons in the secondary somatosensory cortex (SII) of two monkeys trained to switch their attention between a tactile pattern recognition task and a visual task. We found that neurons in SII cortex also undergo a predominantly multiplicative modulation in firing rates without affecting the ratio of variance to mean firing rate (i.e., the Fano factor). Furthermore, both additive and multiplicative components of attentional modulation varied dynamically during the stimulus presentation. We then used a standard conductance-based integrate-and-fire model neuron to ascertain which mechanisms might account for a multiplicative increase in firing rate without affecting the Fano factor. Six mechanisms were identified as biophysically plausible ways that attention could modify the firing rate: spike threshold, firing rate adaptation, excitatory input synchrony, synchrony between all inputs, membrane leak resistance, and reset potential. Of these, only a change in spike threshold or in firing rate adaptation affected model firing rates in a manner compatible with the observed neural data. The results indicate that only a limited number of biophysical mechanisms can account for observed attentional modulation.

Action Potentials↗
PubMed2005

The combination of vision and touch depends on spatial proximity.

The nervous system often combines visual and haptic information about object properties such that the combined estimate is more precise than with vision or haptics alone. We examined how the system determines when to combine the signals. Presumably, signals should not be combined when they come from different objects. The likelihood that signals come from different objects is highly correlated with the spatial separation between the signals, so we asked how the spatial separation between visual and haptic signals affects their combination. To do this, we first created conditions for each observer in which the effect of combination--the increase in discrimination precision with two modalities relative to performance with one modality--should be maximal. Then under these conditions, we presented visual and haptic stimuli separated by different spatial distances and compared human performance with predictions of a model that combined signals optimally. We found that discrimination precision was essentially optimal when the signals came from the same location, and that discrimination precision was poorer when the signals came from different locations. Thus, the mechanism of visual-haptic combination is specialized for signals that coincide in space.

Adult↗
PubMed2006

Vision and touch are automatically integrated for the perception of sequences of events.

The purpose of the present experiment was to investigate the integration of sequences of visual and tactile events. Subjects were presented with sequences of visual flashes and tactile taps simultaneously and instructed to count either the flashes (Session 1) or the taps (Session 2). The number of flashes could differ from the number of taps by +/-1. For both sessions, the perceived number of events was significantly influenced by the number of events presented in the task-irrelevant modality. Touch had a stronger influence on vision than vision on touch. Interestingly, touch was the more reliable of the two modalities-less variable estimates when presented alone. For both sessions, the perceptual estimates were less variable when stimuli were presented in both modalities than when the task-relevant modality was presented alone. These results indicate that even when one signal is explicitly task irrelevant, sensory information tends to be automatically integrated across modalities. They also suggest that the relative weight of each sensory channel in the integration process depends on its relative reliability. The results are described using a Bayesian probabilistic model for multimodal integration that accounts for the coupling between the sensory estimates.

Adult↗
PubMed1999

Geophysical variables and behavior: LXXXV. Sudden infant death, bands of geomagnetic activity, and pc1 (0.2 to 5 HZ) geomagnetic micropulsations.

Pc1s (continuous pulsations) within the geomagnetic field, whose durations are about 30 minutes but which can reoccur several times nightly, are observed during periods when global geomagnetic activity is very low (less than 10 nT). The hypothesis that these 0.2 to 5 Hz synchronized micropulsations or hydromagnetic emissions might stimulate physical chemical cascades within the brain that precipitate the sudden death in infants was tested by correlational analysis for a two-year period (1960-1961) for Ontario. Results were consistent with the hypothesis that the monthly incidences of these unexpected deaths, pcl micropulsations and geomagnetic activity less than 10 nT displayed a shared source of variance. Implications are discussed.

California↗
PubMedDate not supplied

Otilonium bromide: a selective spasmolytic for the gastrointestinal tract.

Experimental studies have shown that otilonium bromide (OB) inhibits both baseline and chemically or physically stimulated gastrointestinal motility. The spasmolytic activity of OB in the gastrointestinal tract occurs at doses that do not affect gastric secretion or produce typical atropine-like side-effects. The mechanism of action is composite: interference with calcium ion movement from intra- and extracellular sites; blockade of calcium channels; and binding to muscarinic receptors and tachykinin neurokinin-2 receptors. Pharmacokinetic studies have shown that OB accumulates in the lower intestine and has poor systemic absorption. Clinical studies have confirmed OB as a potent spasmolytic drug with a good tolerability profile. Studies in patients with irritable bowel syndrome demonstrated OB to be superior to placebo and reference drugs in parameters such as pain, abdominal distension and motility. The composite and local mechanism of OB action reduces hypermotility and modulates visceral sensation: factors thought to be responsible for pain improvement recorded in clinical trials. The compound is marketed worldwide and no serious adverse events have been reported as yet, confirming its excellent tolerability.

Animals↗
PubMedDate not supplied

Developmental patterns of physiological response to a multisensory intervention in extremely premature and high-risk infants.

OBJECTIVE: To compare the developmental patterns of heart rate (HR), respiratory rate (RR), and hemoglobin oxygen saturation (SaO2) of premature infants with and without central nervous system (CNS) injury, and evaluate whether a multisensory intervention altered this development. SAMPLE: Thirty-seven premature infants born at 23-26 weeks with normal head ultrasounds or at 24-32 weeks and diagnosed with periventricular leukomalacia (PVL) and/or intraventricular hemorrhage (IVH) were studied at 33-35 weeks postconceptional age. DESIGN: Infants were randomly assigned to control and experimental groups. The experimental group infants received auditory, tactile, visual, and vestibular (ATVV) multisensory intervention twice daily from 33 weeks postconceptional age (PCA) until hospital discharge. MAIN OUTCOME MEASURES: HR, RR, and SaO2 were continuously monitored during baseline, intervention, and the 30-minute postintervention period. RESULTS: Between 33 and 35 weeks PCA, control group infants with and without CNS injury and experimental group infants without CNS injury had a significant decrease in resting mean HR, whereas RR and SaO2 remained stable. The infants with PVL who received the intervention showed increases in HR even at rest. CONCLUSIONS: The absence of a weekly decline in HR for experimental group infants with PVL suggests that PVL may affect maturation of the autonomic nervous system and increase risk of decelerative HR changes and associated clinical compromise. Infants diagnosed with PVL should be closely monitored during procedures or interventions that may be stressful or involve handling. Further research is needed to tailor multisensory interventions for infants with PVL.

Acoustic Stimulation↗
PubMed2006

Practice makes perfect: the neural substrates of tactile discrimination by Mah-Jong experts include the primary visual cortex.

BACKGROUND: It has yet to be determined whether visual-tactile cross-modal plasticity due to visual deprivation, particularly in the primary visual cortex (V1), is solely due to visual deprivation or if it is a result of long-term tactile training. Here we conducted an fMRI study with normally-sighted participants who had undergone long-term training on the tactile shape discrimination of the two dimensional (2D) shapes on Mah-Jong tiles (Mah-Jong experts). Eight Mah-Jong experts and twelve healthy volunteers who were naïve to Mah-Jong performed a tactile shape matching task using Mah-Jong tiles with no visual input. Furthermore, seven out of eight experts performed a tactile shape matching task with unfamiliar 2D Braille characters. RESULTS: When participants performed tactile discrimination of Mah-Jong tiles, the left lateral occipital cortex (LO) and V1 were activated in the well-trained subjects. In the naïve subjects, the LO was activated but V1 was not activated. Both the LO and V1 of the well-trained subjects were activated during Braille tactile discrimination tasks. CONCLUSION: The activation of V1 in subjects trained in tactile discrimination may represent altered cross-modal responses as a result of long-term training.

Adult↗