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At least 919 records · Page 51Linked to original sources
PubMed1998

Ineffective perfusion-contraction matching in conscious, chronically instrumented pigs with an extended period of coronary stenosis.

Several models purported to represent hibernating myocardium involve a coronary stenosis (CS) to reduce blood flow (BF) and function without eliciting necrosis in anesthetized pigs. The goal of the present study was to determine whether sustained moderate reduction in coronary BF in conscious pigs induced hibernating myocardium, ie, perfusion-contraction matching with no necrosis. These experiments were conducted in conscious pigs chronically instrumented with a coronary artery BF probe and hydraulic occluder, left ventricular (LV) pressure gauge, and wall thickening (WT) crystals in the potentially ischemic and nonischemic zones. The hydraulic occluder was inflated to induce a stable 41+/-4% reduction in BF for 24 hours. Ischemic zone systolic WT fell initially with CS and then continued to decline during the period of CS even though blood flow did not change further, suggesting the induction of myocardial stunning. At 2 days after release of CS, WT was still depressed by 48+/-15%. Assessment of necrosis by histology or triphenyltetrazolium chloride showed 40+/-5% multifocal patchy necrosis interspersed with normal tissue involving the inner one third to one half of the ventricular wall. Regional myocardial BF (radioactive microsphere technique) was assessed by dividing the entire LV into an average of 488+/-59 pieces and examining the spatial distribution of BF within the area at risk (AAR). BF in the samples in the area of patchy necrosis was reduced (-66+/-4% from a baseline of 1.55+/-0.27 mL x min(-1) x g(-1)), whereas BF was maintained in samples in the AAR without necrosis (-2+/-7% from a baseline of 1.25+/-0.22 mL x min(-1) x g(-1)). These findings indicate that when hypoperfusion induced by CS in conscious pigs is sustained, the result is necrosis rather than hibernating myocardium. The remainder of the AAR, which lacked necrosis, might have been mistaken for hibernating myocardium had only histology been evaluated and BF not been measured and found to be at normal levels.

Animals↗
PubMed1998

Serum S-100 and neuron-specific enolase for prediction of regaining consciousness after global cerebral ischemia.

BACKGROUND AND PURPOSE: The aim of our study was to assess the use of S-100 protein (S-100) and neuron-specific enolase (NSE) in serum and cerebrospinal fluid (CSF) for the prediction of patients' regaining consciousness after acute global cerebral ischemia. METHODS: Sixty-four unconscious patients were followed until the return of consciousness or until death/vegetative state. Serum and CSF samples for measurement of S-100 and NSE using an immunoradiometric assay technique were obtained 24 hours (serum) and 48 hours (CSF) after the acute event and correlated with patient outcome. RESULTS: Values for serum S-100 protein, serum NSE, CSF S-100, and CSF NSE were significantly different in the 2 outcome groups. A serum S-100 value of >0.7 micrograms/L was found to be a predictor of not regaining consciousness, with a high positive predictive value (95%) and high specificity (96%). CONCLUSIONS: S-100 protein used as serum marker 24 hours after acute global cerebral ischemia gives reliable and independent information on the outcome of the patient that is comparable or superior to that obtained with CSF markers. Therefore, S-100 may be a serum marker of brain cell damage useful for clinical assessment of these patients.

Adult↗
PubMed1975

Effects of morphine on coronary and left ventricular dynamics in conscious dogs.

We studied the effects of i.v. 2 mg/kg morphine sulfate (MS) on coronary blood flow and resistance, left ventricular (LV) diameter and pressure (P), rate of change of pressure (dP/dt), and dP/dt/P in conscious dogs. An initial transient reduction in coronary vascular resistance, associated with increases in heart rate, dP/dt, dP/dt/P, and reductions in LV end-diastolic and end-systolic size were observed. This was followed by a prolonged increase in mean coronary vascular resistance, lasting from 5 to 30 min, while heart rate, arterial pressure, and LV end-diastolic diameter returned to control levels and dP/dt/P remained slightly but significantly above control. At 10 min, late diastolic coronary flow had fallen from 44 plus or minus 3 ml/min to a minimum level of 25 plus or minus 3 ml/min, while late diastolic coronary resistance had risen from 1.68 plus or minus 0.10 to 3.04 plus or minus 0.28 mm Hg/ml/min. Morphine also induced substantial coronary vasoconstriction when heart rate was held constant. Neither the MS-induced coronary vasoconstriction nor the positive inotropic response was abolished by bilateral adrenalectomy. The positive inotropic response of MS was reversed after beta blockade, but not the coronary vasoconstriction. Alpha receptor blockade abolished the late coronary vasoconstriction effects of morphine, and only dilatation occurred. In anesthetized dogs MS failed to produce late coronary vasoconstriction. Coronary after a respiratory-depressant dose of morphine, 10 mg/kg i.v. Smaller doses of MS, 0.25 mg/kg every 15 min, produced significant coronary vasoconstriction after a total dose of 0.75 mg/kg in the conscious dogs. The effects of morphine may differ in the normal dog and man and may vary depending upon the presence or absence of coronary artery disease. However, in the normal conscious dog, MS elicits a mild beta adrenergic increase in contractility and an important coronary vasoconstrictor effect, which is mediated through alpha adrenergic receptors.

Adrenalectomy↗
PubMed2006

Tracking the recovery of consciousness from coma.

Predicting the chances of recovery of consciousness and communication in patients who survive their coma but transit in a vegetative state or minimally conscious state (MCS) remains a major challenge for their medical caregivers. Very few studies have examined the slow neuronal changes underlying functional recovery of consciousness from severe chronic brain damage. A case study in this issue of the JCI reports an extraordinary recovery of functional verbal communication and motor function in a patient who remained in MCS for 19 years (see the related article beginning on page 2005). Diffusion tensor MRI showed increased fractional anisotropy (assumed to reflect myelinated fiber density) in posteromedial cortices, encompassing cuneus and precuneus. These same areas showed increased glucose metabolism as studied by PET scanning, likely reflecting the neuronal regrowth paralleling the patient's clinical recovery. This case shows that old dogmas need to be oppugned, as recovery with meaningful reduction in disability continued in this case for nearly 2 decades after extremely severe traumatic brain injury.

Coma↗
PubMed2003

Do patients with schizophrenia consciously recollect emotional events better than neutral events?

OBJECTIVE: The influence of the emotional valence of words on conscious awareness was assessed in patients with schizophrenia. METHOD: The remember/know procedure was used to test 24 patients with schizophrenia and 24 normal comparison subjects. RESULTS: Patients' "remember" responses and conscious recollection were more frequent for emotional words than for neutral words. In contrast, the levels of "know" responses and familiarity were independent of emotional words. CONCLUSIONS: Patients with schizophrenia consciously recollected emotional words better than neutral words.

Adult↗
PubMed1991

Level of consciousness on arrival in the recovery room and the development of early respiratory morbidity.

An audit review of 16,065 patients undergoing operative procedures under general anaesthesia was carried out to examine the relationship between early postoperative respiratory complications and the level of consciousness of patients on arrival in the recovery room. In patients aged over ten years, the incidence of respiratory complications was significantly (P less than 0.005) related to the level of consciousness independent of ASA grade or age. Since the level of consciousness of patients arriving in the recovery room could be modified by changes to anaesthetic practice it is concluded that a significant reduction in respiratory complications might be possible if anaesthetists used general anaesthetic techniques which returned patients awake to the recovery room.

Age Factors↗
PubMedDate not supplied

KT-1000 arthrometer: conscious and unconscious test results using 15, 20, and 30 pounds of force.

A recent published report indicated that the reliability and validity of anterior laxity measurements obtained by using the KT-1000 arthrometer were questionable. The purpose of our study was to examine the diagnostic validity of anterior laxity measurements testing patients in conscious and unconscious states using the KT-1000 arthrometer at 15, 20, and 30 pounds of force. The sample included 68 patients with confirmed anterior cruciate ligament disruption. They were given anterior-posterior drawer tests at 20 degrees in both unconscious and conscious states; measurements were recorded at 15, 20, and 30 pounds of force. The results indicated that the measurements in the unconscious state were significantly higher (P less than 0.01) than the values obtained in the conscious state. The anterior cruciate ligament-disrupted knees produced significantly higher (P less than 0.01) anterior laxity. The difference between anterior cruciate ligament-disrupted knees and normal knees grew significantly larger (P less than 0.01) as force increased. More patients demonstrated a difference greater than 2 mm between anterior cruciate ligament-disrupted knees and normal knees at 30 pounds (81% to 83%) than at 20 pounds (64% to 72%) of force. Seventy-nine percent of the patients demonstrated a compliance index difference greater than 1 mm using 15 and 30 pounds between the normal and anterior cruciate ligament-disrupted knee. These data provide statistical validity for the compliance index and support for the use of anterior laxity measurements at 30 pounds of force. However, approximately 20% of these patients did not demonstrate an anterior cruciate ligament-disrupted-normal knee difference greater than 2 mm or a compliance index difference of greater than 1 mm.

Anterior Cruciate Ligament↗
PubMed1988

[Preconscious and conscious stimulation of erotic imagination].

The stimulation of erotic fantasies through the association of relaxation and erotic conscious or preconscious suggestions has been evaluated. This study was attempted following positive results in the stimulation of fantasmatic activity in alexithymic subjects with a similar procedure. Thirty female subjects, allocated into three groups practiced relaxation daily for two weeks including three sessions with psychological measures. During the second week, erotic suggestions, preconscious for one group and conscious for another one, were added. The third group (control) received only relaxation throughout. Results have shown an increase of sexual arousal and erotic imagery during the sessions with erotic suggestions. Sexual activities and desire increased in the two experimental groups. There was no difference between the effects of the preconscious and conscious suggestions. Possible clinical applications of such a procedure are discussed.

Adult↗
PubMed2000

Pattern of expanding consciousness in midlife women: creative movement and the narrative as modes of expression.

This study is based on Newman's theory of expanding consciousness; it expands Newman's method to include creative movement as a mode of expression. The researcher engaged in two in-depth interviews and one creative movement group experience with each of 17 midlife women. Results demonstrate expanding consciousness at midlife, with patterns of meaning identified in relationships with others, self, and spirit as well as challenges of loss, illness, and threats to relationships. Activities of consciousness were choosing, balancing, accepting, and letting go. Concepts of flow, turbulence, and a movement dialectic were identified in study findings. Creative movement supported self-awareness.

Adult↗
PubMed2004

Relaxin modifies systemic arterial resistance and compliance in conscious, nonpregnant rats.

Relaxin emanates from the corpus luteum of the ovary and circulates during pregnancy. Because the hormone is a potent renal vasodilator and mediates the renal vasodilation and hyperfiltration of pregnancy in conscious rats, we reasoned that it might also contribute to the broader cardiovascular changes of pregnancy. We began investigating this concept by testing whether relaxin can modify systemic arterial hemodynamics and load when chronically administered to nonpregnant rats. The major objectives of the present work were to determine whether relaxin administration to nonpregnant rats 1) modifies cardiac output (CO), systemic vascular resistance, and global arterial compliance (AC), and 2) regulates the passive mechanics of isolated arteries. To accomplish the first objective, we developed a conscious rat model for assessment of global AC. Passive mechanics of small renal arteries were assessed using a pressure arteriograph. Chronic administration of recombinant human relaxin by sc osmotic minipump to conscious, female, nonpregnant rats reduced the steady arterial load by decreasing systemic vascular resistance, increased CO, and reduced the pulsatile arterial load by increasing global AC as quantified by two indices-AC estimated from the diastolic decay of aortic pressure and CO and AC estimated by the ratio of stroke volume-to-pulse pressure. In another group of rats, relaxin administration also regulated the passive mechanics of small renal arteries, indicating that, in addition to reduction in vascular smooth muscle tone, modification of the vascular structure (e.g. extracellular matrix) contributes to the increase in global AC. These findings suggest a role for relaxin in the systemic hemodynamic changes of pregnancy, as well as novel therapeutic potential for relaxin in modifying arterial stiffness and cardiac afterload.

Animals↗
PubMed2000

Bilateral focal motor status epilepticus with retained consciousness after stroke.

Bilateral motor seizures with retained consciousness are rare and often mistaken for pseudoseizures. In the few reported cases, the seizures were brief and the underlying lesion usually was a tumor. Here the authors describe a patient with bilateral focal motor status epilepticus with retained consciousness after a stroke. A seizure should be considered as the possible cause of continuous bilateral limb movements with retained consciousness.

Aged↗
PubMed2004

Consciousness and neurosurgery.

The neuronal basis of consciousness is the greatest challenge to the scientific worldview. Much relevant empirical work is carried out on the minimal neuronal mechanisms underlying any one specific conscious percept. Two broad approaches are popular among brain scientists: electrophysiological recordings from individual neurons in the cortex of behaving monkeys or behavior combined with functional brain imaging in humans. However, many aspects of consciousness are problematic or remain off-limits to the former approach, while the latter one lacks sufficient spatial and temporal resolution to monitor individual neurons that are key to perception, thought, memory, and action. It is here that neurosurgeons, probing the living human brain on a daily basis, can play a decisive role. This article explores the contributions of neurosurgeons to this quest and outlines some of the results that have already been achieved.

Animals↗
PubMed1991

Difference in pressor responses to NG-monomethyl-L-arginine between conscious and anesthetized rats.

NG-Monomethyl-L-arginine (L-NMMA; 0.1-10 mg/kg, i.v.), a selective inhibitor of nitric oxide (NO) synthesis derived from L-arginine, elicited a greater increase in blood pressure in urethane/alpha-chloralose- and pentobarbital-anesthetized rats than in conscious Wistar rats. The pressor response to phenylephrine was almost equivalent in both conscious and anesthetized rats. These findings suggest that the experimental conditions (anesthetized or conscious) modify the spontaneously released NO's contribution to blood pressure regulation in vivo.

Anesthetics↗
PubMed2005

Ongoing spontaneous activity controls access to consciousness: a neuronal model for inattentional blindness.

Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its interactions with stimulus-induced activation. Simulations help characterize two main states of activity. First, spontaneous gamma-band oscillations emerge at a precise threshold controlled by ascending neuromodulator systems. Second, within a spontaneously active network, we observe the sudden "ignition" of one out of many possible coherent states of high-level activity amidst cortical neurons with long-distance projections. During such an ignited state, spontaneous activity can block external sensory processing. We relate those properties to experimental observations on the neural bases of endogenous states of consciousness, and particularly the blocking of access to consciousness that occurs in the psychophysical phenomenon of "inattentional blindness," in which normal subjects intensely engaged in mental activity fail to notice salient but irrelevant sensory stimuli. Although highly simplified, the generic properties of a minimal network may help clarify some of the basic cerebral phenomena underlying the autonomy of consciousness.

Arousal↗
PubMed1989

[The effects of the intracerebroventricular administration of cimetidine on hemodynamics in conscious rats: relation to the sympathetic nervous system].

Histamine H2-receptor antagonists administered into the central nervous system have been shown to increase arterial pressure (AP) in anaesthetized animals (Paakkari et al., 1982). Few studies have been reported on the effects of centrally administered cimetidine (CIM), one of the histamine H2-receptor antagonists, in conscious animals. However, the mechanism of the pressor action of histamine H2-receptor antagonists remains unclear. The present study was designed to investigate the hemodynamic effects of intracerebroventricular (i.c.v.) CIM and the interaction between the sympathetic nervous system and histamine receptor system in conscious rats. Male Wistar rats weighing 200 gr were prepared for the experiment under a conscious and minimally restricted state. Five micrograms of i.c.v. saline (SAL-ICV group, n = 5) did not produce significant changes in mean arterial pressure (MAP) or heart rate (HR) (MAP from 85.6 +/- 3.4 to 86.0 +/- 4.3 mmHg and HR from 395.0 +/- 13.9 to 395.2 +/- 8.2 bpm, respectively). Twenty micrograms of i.c.v. phenoxybenzamine (POB-ICV group, n = 6) decreased MAP from 95.8 +/- 4.1 to 85.2 +/- 3.1 mmHg, -10.7 +/- 2.2 mmHg as delta MAP, and increased HR from 392.5 +/- 8.5 to 435.3 +/- 13.9 bpm, +42.8 +/- 6.8 bpm as delta HR. Two-hundred micrograms of intravenous (i.v.) POB (POB-IV group, n = 5) also decreased MAP from 96.0 +/- 4.3 to 71.0 +/- 5.1 mmHg, -25.0 +/- 2.7 mmHg as delta MAP, and increased HR from 395.8 +/- 10.5 to 473.0 +/- 12.4 bpm, +77.2 +/- 7.6 bpm as delta HR. The changes in MAP and HR were much greater in the POB-IV group than those in the other two groups. The subsequent i.c.v. administration of 250 micrograms of CIM induced an increase in MAP (+19.4 +/- 1.7 mmHg as delta MAP) and a decrease in HR (-36.4 +/- 3.1 bpm as delta HR) in the SAL-ICV group, which continued for at least 30 minutes producing peak effects 2 minutes after i.c.v. administration of CIM. However, an elevation of MAP caused by i.c.v. CIM was much more inhibited in the POB-ICV group than in the POB-IV group (+2.5 +/- 0.7 mmHg as delta MAP in the POB-ICV group and +5.0 +/- 1.3 mmHg as delta MAP in the POB-IV group, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Projective identification and consciousness alteration: a bridge between psychoanalysis and neuroscience?

The authors claim that projective identification in the process of analysis should be considered in a circumscribed manner and seen as a very specific type of communication between the patient and the analyst, characterised through a modality that is simultaneously active, unconscious and discrete. In other words, the patient actively, though unconsciously and discretely--that is, in specific moments of the analysis--brings about particular changes in the analysts state. From the analyst's side, the effect of this type of communication is a sudden change in his general state--a sense of passivity and coercion and a change in the state of consciousness. This altered consciousness can range from an almost automatic repetition of a relational script to a moderate or serious contraction of the field of attention to full-fledged changes in the analyst's sense of self. The authors propose the theory that this type of communication is, in fact, the expression of traumatic contents of experiences emerging from the non-declarative memory. These contents belong to a pre-symbolic and pre-representative area of the mind. They are made of inert fragments of psychic material that are felt rather than thought, which can thus be viewed as a kind of writing to be completed. These pieces of psychic material are the expression of traumatic experiences that in turn exercise a traumatic effect on the analyst, inducing an altered state of consciousness in him as well. Such material should be understood as belonging to an unrepressed unconscious. Restitution of these fragments to the patient in representable forms must take place gradually and without trying to accelerate the timing, in order to avoid the possibility that the restitution itself constitute an acting on the part of the analyst, which would thus be a traumatic response to the traumatic action of the analytic material.

Consciousness↗
PubMed2006

The medial temporal lobe distinguishes old from new independently of consciousness.

Although it is widely accepted that the medial temporal lobes (MTLs) are critical for becoming aware that something happened in the past, there is virtually no evidence whether MTL sensitivity to event oldness also depends on conscious awareness. Using event-related functional magnetic resonance imaging, we show that activity in posterior MTL tracks whether an item is actually old (true oldness), regardless of participants' awareness of oldness (perceived oldness). Confirming its sensitivity to the objective nature of the stimulus, activity in this region was strongly correlated with individual memory performance (r = 0.74). At the same time, we found that memory errors (misses) were associated with activity in an anterior MTL region, which signaled whether an item was consciously experienced as new (perceived novelty). Logistic regression analyses based on individual trial activity indicated that the two MTL regions showed opposing relationships with behavior, and that memory performance was determined by their joint activity. Furthermore, functional connectivity analyses showed that perceived novelty activity in the ANTERIOR [corrected] MTL inhibited true oldness activity in the POSTERIOR [corrected] MTL. These findings indicate that participants' behavior reflected the combined effects of multiple MTL regions. More generally, our results show that parts of MTL can distinguish old from new independently of consciousness.

Adult↗
PubMed1993

Effect of a new colonic prokinetic compound, T-1815, on gastrointestinal motility in anesthetized and conscious fasted dogs.

Effect of T-1815, a new colonic prokinetic compound, on gastrointestinal motility was studied in anesthetized and conscious dogs fasted for 24 hr before experiment. In anesthetized dogs, intravenous injection of T-1815 in doses of 0.3-3.0 mg/kg caused a biphasic effect on the gastric motility, a slight decrease followed by a slight increase. While the compound elicited only an increase in motility of the duodenum, jejunum and colon. In the colon, high-amplitude contractions were observed in 2 out of 5 animals at 1 mg/kg, i.v. of T-1815 and 4 out of 5 animals at 3 mg/kg. Bethanechol at 0.01 mg/kg, i.v. produced only a potentiation of the motility in all of the sites, but never induced high-amplitude contractions in the colon. During the interdigestive state in conscious dogs, intravenous T-1815 at 1 and 3 mg/kg caused contractions similar to the interdigestive phase III contractions at the stomach and duodenum in only 2 out of 7 experiments, and colonic motility was slightly depressed at 3 mg/kg. Oral administration of T-1815 at 30 and 50 mg/kg did not elicit the phase III-like contractions but produced persistent contractions at the stomach and duodenum in 2 out of 4 conscious animals during the interdigestive state. In the proximal and middle colon, high-amplitude contractions were observed in 5 out of 7 animals by 10-50 mg/kg, p.o. of T-1815. From the above results, it is concluded that the pharmacological effect of T-1815 on gastrointestinal motility is different from that of the cholinergic agonist. In addition, T-1815 seems to have a characteristic to induce high-amplitude contractions which are known to be closely related to defecation.

Administration, Oral↗