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PubMed1992

Pressure recovery in aortic stenosis: an in vitro study in a pulsatile flow model.

OBJECTIVES: This study was designed to study pressure recovery in various models of aortic valve stenosis by performing hemodynamic measurements under physiologic conditions in a pulsatile aortic flow circuit. The results were used to validate calculations of pressure recovery based on theoretic considerations derived from fluid dynamics. BACKGROUND: Pressure recovery in aortic stenosis has not been systematically analyzed. METHODS: Stenoses varying in size, shape (circular, Y-shaped, slitlike) and inlet configuration (sharp-edged, nozzle-shaped inlet, artificially stenosed bioprostheses) were used. Aortic pressures were measured at multiple sites distal to the stenotic orifice to determine pressure gradients and recovery. RESULTS: With decreasing orifice area (2, 1.5, 1 and 0.5 cm2) pressure recovery increased (5, 7, 10 and 16 mm Hg, respectively) and the index pressure recovery to maximal peak to peak gradient decreased (56%, 37%, 24% and 14%, respectively). For a given orifice size of 0.5 cm2, this index ranged between 12% for a Y-shaped orifice and 15% for a circular orifice with a nozzle (cardiac output 4 liters/min). Increasing the cardiac output increased pressure recovery, whereas the ratio of pressure recovery to maximal pressure gradient remained constant. CONCLUSIONS: The index pressure recovery to transvalvular pressure gradient, which expresses the hemodynamic relevance of pressure recovery, decreases with increasing severity of aortic stenosis but is independent of transvalvular flow. Thus, pressure recovery is of minor importance in severe aortic stenosis but may account for discrepancies between Doppler and manometric gradients observed in patients with mild to moderate aortic stenosis or a prosthetic valve in the aortic position.

Aortic Valve Stenosis↗

PubMed2005

Role of phosphorylation of Thr(17) residue of phospholamban in mechanical recovery during hypercapnic acidosis.

OBJECTIVES: To assess the time course of phosphorylation of phospholamban residues, the underlying mechanisms determining these phosphorylations, and their functional impact on the mechanical recovery during acidosis. METHODS: Langendorff perfused rat hearts were submitted to 30 min of hypercapnic acidosis. Contractility, relaxation, and phosphorylation of phospholamban residues, immunodetected by specific antibodies, were determined. RESULTS: Acidosis produced a mechanical impairment followed by a spontaneous recovery, most of which occurred within the first 3 min of acidosis (early recovery). During this period, contractility and relaxation recovered by 67+/-9% and 77+/-11%, respectively, from its maximal depression, together with an increase in the Ca(2+)-calmodulin-dependent protein kinase II (CaMKII)-dependent phosphorylation of Thr(17). The CaMKII inhibitor KN-93, at 1, 5 and 10 microM, decreased Thr(17) phosphorylation to basal levels and produced a similar impairment of the early relaxation recovery (50%). However, only 5 and 10 microM KN-93 inhibited the early contractile recovery and completely blunted the late mechanical recovery. Inhibition of the reverse mode of the Na(+)/Ca(2+) exchanger by KB-R7943 decreased Thr(17) phosphorylation but accelerated the early contractile recovery. CONCLUSIONS: CaMKII-dependent Thr(17) phosphorylation significantly increased at the beginning of acidosis, is responsible for 50% of the early relaxation recovery, and is linked to the activation of the reverse Na(+)/Ca(2+) mode. The early contractile recovery and the late mechanical recovery are dependent on CaMKII but independent of the phosphorylation of the Thr(17) residue of phospholamban. The reverse Na(+)/Ca(2+) mode has an additional negative effect that opposes the early mechanical recovery.

Acidosis↗

PubMed2005

Dip-angle influence on areal DNAPL recovery by co-solvent flooding with and without pre-flooding.

A two-dimensional (2D) laboratory model was used to study effects of gravity on areal recovery of a representative dense non-aqueous phase liquid (DNAPL) contaminant by an alcohol pre-flood and co-solvent flood in dipping aquifers. Recent studies have demonstrated that injection of alcohol and co-solvent solutions can be used to reduce in-situ the density of DNAPL globules and displace the contaminant from the source zone. However, contact with aqueous alcohol reduces interfacial tension and causes DNAPL swelling, thus facilitating risk of uncontrolled downward DNAPL migration. The 2D laboratory model was operated with constant background gradient flow and a DNAPL spill was simulated using tetrachloroethene (PCE). The spill was dispersed to a trapped, immobile PCE saturation by a water flood. Areal PCE recovery was studied using a double-triangle well pattern to simulate a remediation scheme consisting of an alcohol pre-flood using aqueous isobutanol ( approximately 10% vol.) followed by a co-solvent flood using a solution of ethylene glycol (65%) and 1-propanol (35%). Experiments were conducted with the 2D model oriented in the horizontal plane and compared to experiments at the 15 degrees and 30 degrees dip-angle orientations. Injection was applied either in the downward or upward direction of flow. Experimental results were compared to theoretical predictions for flood front stability and used to evaluate effects of gravity on areal PCE recovery. Sensitivity experiments were performed to evaluate effects of the alcohol pre-flood on PCE areal recovery. For experiments conducted with the alcohol pre-flood and the 2D model oriented in the horizontal plane, results indicate that 89-93% of source zone PCE was recovered. With injection oriented downward, results indicate that areal PCE recovery was 70-77% for a 15 degrees dip angle and 57-59% for a 30 degrees dip angle. With injection oriented upward, results indicate that areal PCE recovery was 57-60% at the 30 degrees dip angle, which was similar to PCE recovery for injection in the downward flow direction. Lower areal PCE recovery at greater dip angles in either direction of flow was attributed to DNAPL swelling and migration, flood front instabilities and bypassing of the displaced fluid past the extraction wells during the alcohol pre-flood. Additional results demonstrate that the use of an alcohol pre-flood can be beneficial in improving DNAPL recovery in the horizontal orientation, but pre-flooding may reduce areal recovery efficiency in dip-angle orientations. This study also demonstrates the use of theoretical perturbation (fingering) analysis in predicting NAPL recovery efficiency for flooding processes in remediating aquifers with dip angles.

1-Propanol↗

PubMed1998

Recovery of arm function in patients with paresis after traumatic brain injury.

OBJECTIVE: To characterize the frequency of recovery of arm paresis in patients with traumatic brain injury (TBI) admitted to rehabilitation. DESIGN: Retrospective review identifying a cohort of patients with moderate or severe arm paresis after TBI followed at least 6 months postinjury. SETTING: Freestanding acute rehabilitation hospital TBI unit. PATIENTS AND METHODS: Forty-four patients with moderate to severe arm paresis were selected from 264 consecutive admissions and characterized by injury pathology subtype, injury severity (duration of unconsciousness [loss of consciousness, LOC] and posttraumatic amnesia [PTA]), age, and level of paresis according to Brunnstrom Stages of Recovery (BS 1 to 6). Patient groups with and without arm paresis were compared according to these variables (t tests and chi(2)). MAIN OUTCOME MEASURES: Recovery of arm paresis to isolated motor function (BS 5 or 6) and time to achieve recovery. Recovered and nonrecovered patients were compared (Mann-Whitney, t tests, and chi(2)) on injury severity, initial level of paresis, age, time to rehabilitation admission, and pathology subtype. Time to recovery was compared for patients at different levels of initial paresis, ranges of LOC, and pathology subtypes (Mann-Whitney and Kruskal-Wallis tests). RESULTS: Forty-four patients (17%) had moderate (BS 3 to 4) or severe (BS 1 to 2) paresis at rehabilitation admission. They were more severely injured than nonparetic patients based on longer LOC (p < .002) and PTA (p < .009). Thirty-six patients (82%) recovered by 6 months; 72% of these recovered by 2 months. If still paretic at 2 months, only 56% recovered. Mean recovery time was 6.9 weeks (SD, 6.1) from injury. Time to recovery was best predicted by initial level of paresis and injury severity (r2 = .48), but not age. Patients with diffuse injury tended towards a more protracted recovery (7.9 weeks, SD 6.5) than patients with focal injury (4.2 weeks, SD 3.9) (p = .08) and only those with diffuse injury showed further recovery after 3 months. CONCLUSIONS: Arm paresis after TBI is relatively infrequent. Most patients recover by 2 months but later recovery is possible, especially in patients with primarily diffuse brain damage. Recovery is highly related to initial impairment, injury severity, and distribution of brain injury.

Adolescent↗

PubMed1998

Haematological recovery after high-dose consolidation chemotherapy with peripheral blood progenitor cell rescue: the effects of the mobilization regimen and post-transplant growth factors.

PURPOSE: Peripheral blood progenitor cells (PBPC), mobilized by chemotherapy, growth factors (GF) or the combination of these modalities are currently used in most autologous transplants settings. Patient selection factors and infused cell numbers have been related to the rate of haematological recovery after transplant (p-Tx). The effect of the mobilization regimen on haematological recovery has rarely been reported and is addressed herein. The value of p-Tx GF use is also evaluated. METHODS: A literature review identified studies reporting both mobilization results and haematological recovery (time to ANC > 0.5 or 1.0 x 10(9)/1 and PLT > 20 or 50 x 10(9)/1). The studies are listed in tables showing the mobilization regimen, disease, infused CD34+ cell and CFU-GM dose, p-TX GF use and haematological recovery. The ranges of recovery times for each transplant setting are summarized in a figure in addition to the ranges of recovery times using GF after autologous bone marrow transplants in controlled studies. RESULTS: Transplantation of cells mobilized by G-CSF results in faster haematological recovery than transplantation of cells mobilized by GM-CSF. This difference disappears when chemotherapy is included in the mobilization regimen. GF have minimal effect on haematological recovery after transplantation of PBPC mobilized by chemotherapy plus GF and some effect on neutrophil recovery after transplants of PBPC mobilized by GF only. CONCLUSIONS: Recovery after PBPC transplantation depends on the mobilization method and is best predictable when mobilization occurs with chemotherapy plus GF. In this situation, the value of post-transplant growth factors is questionable. Careful choice of the mobilization method, including optimal timing of leucapheresis and patient selection factors, determine the leucapheresis yield and thus the rate of haematological recovery.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Discharge properties of pigeon single auditory nerve fibers after recovery from severe acoustic trauma.

The time course of recovery of compound action potential (CAP) thresholds was observed in individual adult pigeons after severe acoustic trauma. Each bird had electrodes implanted on the round window of both ears. One ear was exposed to a tone of 0.7 kHz at 136-142 dB SPL for 1 hr under general anesthesia. Recovery of CAP audiograms was monitored twice a week after trauma. Single unit recordings from auditory nerve fibers were made after 3 weeks and after 4 or more months of the exposure. The CAP was abolished immediately after overstimulation in all animals. Based on the temporal patterns of functional recovery of the CAP three groups of animals were identified. The first group was characterized by fast functional recovery starting immediately after trauma followed by a return to pre-exposure values within 3 weeks. In the second group, slow functional recovery of threshold started 1-2 weeks after trauma followed by a return to pre-exposure values by 4-5 weeks. A mean residual hearing loss of 26.3 dB at 2 kHz remained. The third group consisted of animals that did not recover after trauma. Three weeks after the exposure, tuning curves of single auditory nerve fibers were very broad and sometimes irregular in shape. Their thresholds hovered around 120 dB SPL. Spontaneous firing rate and driven rate were much reduced. Four or more months after exposure, the thresholds and sharpness of tuning of many single units were almost completely recovered. Spontaneous firing rate and driven rate were comparable to those of control animals. In the slow recovery group neuronal tuning properties showed less recovery, especially at frequencies above the exposure frequency. Thresholds and sharpness of tuning were normal at frequencies below the exposure frequency, but were much poorer at frequencies above the exposure. Spontaneous firing rate was much reduced in fibers with high characteristic frequencies. In fast recovering animals, the papilla was repopulated with hair cells after 4 months. In slow recovering animals, short (abneural) hair cells were still missing over large parts of the papilla after 4 months of recovery. Residual short (abneural) hair cell loss was largest at two areas, one more basal and the other more apical to the characteristic place of the traumatizing frequency. The results show that, in adult birds, functional recovery from severe damage to both short (abneural) and tall (neural) hair cells occurs. However, the onset of recovery is delayed and the time course is slower than after destruction of short (abneural) hair cells alone. Also, recovery is incomplete, both functionally and morphologically. There is residual permanent hearing loss, and regeneration of short (abneural) hair cells is incomplete.

Action Potentials↗

PubMed2007

Structural role of tyrosine 98 in photoactive yellow protein: effects on fluorescence, gateway, and photocycle recovery.

We have recently shown that the Y98Q mutant of PYP has a major effect on the photocycle kinetics ( approximately 40 times slower recovery). We have now determined the crystal structure of Y98Q at 2.2 A resolution to reveal the role of residue Y98 in the PYP photocycle. Although the overall structure is very similar to that of WT, we observed two major effects of the mutation. One obvious consequence is a conformational change of the beta4-beta5 loop, which includes a repositioning of residue M100. It had previously been shown that the photocycle is slowed by as much as 3 orders of magnitude when residue M100 is substituted or when the conformation is altered as in Rhodocista centenaria PYP. To investigate whether the altered photocycle of Y98Q is due to this repositioning of M100 or is caused by an effect unrelated to M100, we determined the dark recovery kinetics of the Y98Q/M100A mutant. We find the recovery kinetics to be very similar to the M100A single mutant kinetics and therefore conclude that the slower recovery kinetics in Y98Q are most likely due to repositioning of M100. In addition, we find that other substitutions at position 98 (Y98W, Y98L, and Y98A) have differing effects on the photocycle recovery, presumably due to a variable distortion of the beta4-beta5 loop. The second effect of the Y98Q mutation is a repositioning of R52, which is thought to interact with Y98 in WT PYP and now forms new interactions with residues Q99 and Q56. To determine the role of R52, we also characterized an R52A/M100A double mutant and found that the effects on the recovery kinetics ( approximately 2000 slower recovery than WT) are due to unrelated events in the photocycle. Since the Y98Q/M100A recovery kinetics are more similar to those of M100 than R52A/M100A, we conclude that the repositioning of R52, caused by the Y98Q mutation, does not affect the dark state recovery. In addition, it has been proposed that Y98 and P68 are "gateway residues" between which the chromophore must pass during isomerization. We tested the recovery kinetics of mutant P68A and found that, although the gateway may be important for photocycle initiation, its role in recovery to the ground state is minimal.

Bacterial Proteins↗

PubMed2025

Drought recovery in plants triggers a cell-state-specific immune activation.

All organisms experience stress as an inevitable part of life, from single-celled microorganisms to complex multicellular beings. The ability to recover from stress is a fundamental trait that determines the overall resilience of an organism, yet stress recovery is understudied. To investigate how plants recover from drought, we examine a fine-scale time series of RNA sequencing starting 15 min after rehydration following moderate drought. We reveal that drought recovery is a rapid process involving the activation of thousands of recovery-specific genes. To capture these rapid recovery responses in different Arabidopsis thaliana (A. thaliana) leaf cell types, we perform a single-nucleus transcriptome analysis at the onset of drought recovery, identifying a cell type-specific transcriptional state developing independently across cell types. To further validate the cell-type specific transcriptional changes observed during drought recovery, we employ spatial transcriptomics using multiplexed error-robust fluorescence in situ hybridization (MERFISH), revealing anatomical localization of recovery-induced gene expression programs across Arabidopsis leaf tissues. Furthermore, we reveal a recovery-induced activation of the immune system that occurs autonomously, and which enhances pathogen resistance in vivo in A. thaliana, wild tomato (Solanum pennellii) and domesticated tomato (Solanum lycopersicum cv. M82). Since rehydration promotes microbial proliferation and thereby increases the risk of infection, the activation of drought recovery-induced immunity may be crucial for plant survival in natural environments. These findings indicate that drought recovery coincides with a preventive defense response, unraveling the complex regulatory mechanisms that facilitate stress recovery in different plant cell types.

Arabidopsis↗

PubMed2000

Natural recovery from alcohol and drug problems: methodological review of the research with suggestions for future directions.

AIMS: The methodology of studies that reported data on individuals who recovered from an alcohol or other drug problem (cigarette smokers were excluded) without formal help or treatment were reviewed. DESIGN/MEASUREMENTS: Potential studies were identified (a) through computerized literature searches, (b) by reviewing references from key publications and (c) by correspondence with researchers in the field. Studies had to (a) be in English, (b) be published, in press, or presented before the end of 1997, (c) report original results or be part of an original survey and (d) separately report respondents whose recoveries were and were not attributable to treatment. No case studies were included. Eligible studies were evaluated with respect to meeting criteria for (a) natural recovery, (b) methodological rigor and (c) reporting demographic and substance abuse history variables. FINDINGS: Until 1997 only 38 articles (40 different respondent samples) met the inclusion criteria for this review. This small number of studies is not surprising, as natural recovery from substance abuse is a relatively new area of study. Moreover, the majority of the 38 articles were published in the past 8 years. For most studies, descriptions of the respondent samples at pre- and post-recovery were seriously deficient. Alcohol was the most studied drug, with heroin a distant second. Low-risk drinking (78.6%) and limited drug use (46.2%) were commonly reported outcomes in natural recovery studies. CONCLUSIONS: Based on this review, future natural recovery studies should: (a) report respondents' demographic characteristics at the time of their recovery; (b) describe respondents' pre-recovery problem severity; (c) explore in some depth what factors, events or processes are associated with the self-change process; (d) provide corroboration of respondents' self-reports; (e) examine factors related to the maintenance of recoveries; (f) conduct interviews with individuals who have naturally recovered from cocaine, marijuana and polydrug abuse; (g) include a second interview at a later time to examine stability of natural recoveries; and (h) require a minimum 5-year recovery time frame.

Female↗

PubMed2000

Effect of recovery interventions on lactate removal and subsequent performance.

The recovery process in sport plays an essential role in determining subsequent athletic performance. This study investigated the effectiveness of different recovery interventions after maximal exercise. Eighteen trained male cyclists initially undertook an incremental test to determine maximal oxygen consumption. The four recovery interventions tested were: passive, active (50% maximal oxygen uptake), massage, and combined (involving active and massage components). All test sessions were separated by 2 to 3 days. During intervention trials subjects performed two simulated 5 km maximal effort cycling tests (T1 and T2) separated by a 20 min recovery. Performance time for the tests (t1, t2); blood lactate (BLa) during T1, T2, and every 3 min during recovery; and heart rate (HR) during the recovery intervention and T2 were recorded. Combined recovery was found to be better than passive (P<0.01) and either active or massage (P<0.05) in maintenance of performance time during T2. Active recovery was the most effective intervention for removing BLa at minutes 9 and 12, BLa removal during combined recovery was significantly better than passive at minute 3, and significantly better than passive, active, and massage at minute 15. In conclusion, combined recovery was the most efficient intervention for maintaining maximal performance time during T2, and active recovery was the best intervention for removing BLa.

Adult↗

PubMed1995

Blood lactate concentration following exercise: effects of heat exposure and of active recovery in heat-acclimatized subjects.

The purpose of this study was to examine the effect of ambient heat on the decrease in blood lactate concentration ([LA]bl) during passive and during active recovery. Ten trained men performed six 1-min bouts of exercise at 100% VO2peak on a cycle ergometer, with 1-min rest between the bouts. Each subject exercised twice in thermoneutral (22 degrees C, 40% RH, TN), and twice in hot (35 degrees C, 30% RH, H) conditions. Exercise was followed by either 40 min of passive recovery (sitting) or by 20 min active recovery (cycling at 35% VO2peak) and 20 min passive recovery, named thereafter, 'active recovery'. Capillary blood lactate was measured before, 1 min after, and every 5 min during recovery. Heart rate (HR), rectal and skin temperatures (Tre, Tsk) were monitored continuously. VO2 was measured prior to exercise, during the last exercise bout, the first 10 min of recovery, and periodically thereafter. Post-exercise [LA]bl was similar in all treatments (13.5 +/- 1.8, 13.0 +/- 1.3, 14.8 +/- 4.1, 13.3 +/- 2.6 mmol.l-1 for TN-active, TN-passive, H-active and H-passive, respectively). [LA]bl was significantly lower during active, compared to passive recovery in both, TN and H conditions. Environmental heart did not independently affect [LA]bl during passive or active recovery. Exercise resulted in an elevation in Tre in all treatments, with a significantly higher Tre during active recovery in H compared to the other sessions. Likewise, no differences in HR and in VO2 were observed between H and TN conditions during active nor during passive recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗

PubMed2002

Early ST-segment recovery, infarct artery blood flow, and long-term outcome after acute myocardial infarction.

BACKGROUND: Early resolution of ST-segment deviation (ST recovery) on the postthrombolytic electrocardiograms and restoration of "normal" blood flow in the infarct-related artery are associated with improved outcomes after myocardial infarction (MI). METHODS AND RESULTS: To evaluate the relationships between ST recovery, infarct-related artery flow, and late survival we studied 766 patients with electrocardiograms recorded at a median of 167 minutes after thrombolytic therapy. Angiography was performed at 3 weeks, and follow-up was done at a median of 6.3 years (interquartile range [IQR] 5.0-8.4). At 10 years, the survival rates were 55% (95% CI 43-70) in patients with <30% ST recovery in the single lead with maximum ST elevation, 71% (95% CI 64-79) in those with 30% to 70% ST recovery, and 74% (95% CI 68-82) in those with >70% ST recovery (P =.0005), whereas ST recovery measured as the sum of voltage changes of either ST deviation (elevation or depression) or ST elevation was not associated with 10-year survival (log-rank test, P =.06 and P =.34, respectively). In patients with Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow, ST recovery of >70% (vs <30% and 30% to 70%) in the lead with maximum ST elevation was associated with increased late survival (P =.04). On multivariate analysis, the predictors, at admission, of 5-year survival were age (P <.001), ST recovery (measured as a continuous variable, P =.001), diabetes (P =.003) and female gender (P =.02). When the ejection fraction (P =.003) and TIMI flow grade (P =.02) at 3 weeks were included in the analysis, the P value for ST recovery was.08. CONCLUSIONS: ST recovery measured in the single lead with maximum ST elevation was a predictor of late survival, even in patients with TIMI grade 3 flow but ST recovery measured as the sum of voltage changes in all leads with ST deviation was not. This simple electrocardiographic parameter can identify patients with a reduced chance of survival who might benefit from additional therapies.

Aged↗

PubMed2006

Continued suppression of serum TSH level may be attributed to TSH receptor antibody activity as well as the severity of thyrotoxicosis and the time to recovery of thyroid hormone in treated euthyroid Graves' patients.

The cause of continued suppression of serum thyroid-stimulating hormone (TSH) levels during antithyroid drug therapy in some Graves' patients is unclear. Recently, there has been a notable explanation involving the direct inhibition of TSH receptor antibody (TRAb) on TSH secretion in the pituitary gland. The purpose of this study is to verify the relation between TRAb or other clinical parameters and the continued suppression of serum TSH level during antithyroid drug therapy in patients with Graves' disease. We reviewed the medical records of patients with Graves' disease between 1995 and 2002 at Samsung Medical Center. We selected 167 Graves' patients who had been euthyroid for at least 12 months after recovery of serum T3 and T4 levels during the antithyroid drug therapy. We analyzed the correlation of the interval until recovery of serum TSH with the pretreatment clinical parameters. We compared the recovery rates of suppressed TSH levels between pretreatment thyrotrophin-binding inhibitory immunoglobulin (TBII)-positive (>15%) and TBII-negative patients. We also compared the clinical parameters between two groups at the time of diagnosis and after recovery of thyroid hormone. Pretreatment serum T3 level, (131)I uptake, TBII activity, and the time to recovery of T3 or T4/free T4 level showed significant positive correlations with the interval until recovery of serum TSH level ( p < 0.05). Recovery rates of serum TSH levels at 3 months after recovery of thyroid hormone were significantly lower in pretreatment TBII-positive patients than those in TBII-negative patients ( p < 0.01). Serum TSH levels were significantly lower in TBII-positive patients at 3 months after recovery of thyroid hormone ( p < 0.05). TBII activities inversely correlated only with serum TSH levels at 3months after recovery of thyroid hormone ( p < 0.001). In conclusion, continued suppression of serum TSH level may be attributed to TRAb activity as well as the pretreatment severity of thyrotoxicosis and the time to recovery of thyroid hormone in patients with Graves' disease during antithyroid drug therapy.

Adolescent↗

PubMed1994

A psychophysical study of the mechanisms of sensory recovery following nerve injury in humans.

Twenty-four subjects were studied before and up to 1 year after surgery that produced injury to a major sensory branch of the trigeminal nerve. We employed a battery of 11 psychophysical tests, in which the neural mechanisms underlying performance are understood, to study the basis of recovery following nerve injury. Immediately after nerve injury, sensation was profoundly impaired in all subjects. In the following weeks and months, the recovery of performance proceeded in an orderly fashion. Although the rates of recovery varied between subjects, the order of recovery between tasks did not. The recovery rates fell into three distinct categories. Recovery in one task, brush-stroke directional discrimination, was most rapid. Two weeks after nerve injury, 52% of subjects could discriminate brush-stroke direction; by 3 months only one subject could not perform this task. The second category comprised recovery rates for pain thresholds for noxious heat, cold and mechanical stimuli, and to preinjury performance in tasks assessing touch and vibration detection, two-point discrimination, cooling detection and subjective magnitude estimation of mechanical force. The third, slowest group included recovery rates for warming detection and grating orientation discrimination. Early recovery to preinjury performance levels in the brush-stroke direction and one-point versus two-point discrimination tasks was correlated with later recovery to near normal performance in the grating orientation task. The grating orientation task was unique in providing a measure that corresponded consistently with the subjects' reports of sensory deficits. Our psychophysical findings are consistent with neurophysiological data showing that the major primary afferent fibre classes reinnervate the skin at a similar rate. A hypothesis that accounts for the psychophysical findings in this study is that differences in recovery rates between tasks is determined largely by their relative dependencies on functional innervation density. Alternative hypotheses are considered.

Adolescent↗

PubMed1998

Prospective and retrospective studies of recovery in aphasia. Changes in cerebral blood flow and language functions.

Prospective and retrospective language evaluations and single photon emission computed tomography (SPECT) scans were performed in order to study the relationship between post-stroke recovery from aphasia and changes in cerebral blood flow (CBF) in groups of patients who had made a good recovery and those who had not. For the prospective study, 20 right-handed patients with aphasia secondary to an acute cerebrovascular accident (CVA) in the left middle cerebral artery territory received language evaluations with a Japanese Standard Language Test of Aphasia (SLTA), and SPECT scans performed twice, at a mean of 3.2 and a mean of 9.2 months post-onset. Only one slice of SPECT data was analysed. A significant correlation was observed between the severity of the initial language deficit and initial CBF on the left side, but not the right. Initial CBF was not a predictor for future language recovery in either hemisphere. There was a correlation between the change in the left mean hemispheric CBF (but not the right) and the change in the overall SLTA severity rating from 3 to 9 months post-stroke. In the retrospective study, 16 right-handed patients with residual aphasia secondary to CVA in the left middle cerebral artery territory received SLTA and SPECT at a mean of 82.8 months post-onset. The patients had also received initial language evaluation with SLTA at a mean of 6.5 months post-onset. In contrast to the prospective study, the results demonstrated that the mean left hemispheric CBF at approximately 7 years post-onset did not differ between good and poor recovery groups. However, the mean right hemispheric CBF of the good recovery group was higher than that of the poor recovery group in the frontal and the thalamic regions, and also in the left frontal region. The results of these complementary studies suggest that the initial language recovery within the first year post-onset may be linked primarily to functional recovery in the dominant hemisphere, where an increase in CBF was observed at 9 months post-onset. The increased perfusion adjacent to the lesion may be crucial for early recovery in aphasia. Subsequent language recovery and the long-term recovery in aphasia may be related to slow and gradual compensatory functions in the contralateral hemisphere, specifically in the homotopic frontal and thalamic areas.

Adult↗

PubMed2000

Recovery from neuromuscular blockade after either bolus and prolonged infusions of cisatracurium or rocuronium using either isoflurane or propofol-based anesthetics.

UNLABELLED: We examined the recovery characteristics of cisatracurium or rocuronium after bolus or prolonged infusion under either isoflurane or propofol anesthesia. Sixty patients undergoing neurosurgical procedures of at least 5 h were randomized to receive either isoflurane with fentanyl (Groups 1 and 2) or propofol and fentanyl (Groups 3 and 4) as their anesthetic. Groups 1 and 3 received cisatracurium 0.2 mg/kg IV bolus, spontaneously recovered, after which time an infusion was begun. Groups 2 and 4 received rocuronium 0.6 mg/kg IV, spontaneously recovered, and an infusion was begun. Before the end of surgery, the infusion was stopped and recovery of first twitch (T(1)), recovery index, clinical duration, and train-of-four (TOF) recovery was recorded and compared among groups by using appropriate statistical methods. Clinical duration was shorter for rocuronium compared with cisatracurium using either anesthetic. Cisatracurium T(1) 75% recovery after the infusion was shorter with propofol compared with isoflurane. Cisatracurium TOF 75% recovery was similar after either bolus or infusion, but rocuronium TOF 75% recovery after the infusion was delayed. Infusion rates decreased for cisatracurium but remained relatively constant for rocuronium regardless of the anesthetic used. Isoflurane enhances the effect of both muscle relaxants but prolonged cisatracurium recovery more than rocuronium. Of the two muscle relaxants studied, rocuronium's recovery was most affected by length of the infusion. Cisatracurium may be a more desired muscle relaxant for prolonged procedures because recovery was least affected by prolonged infusion. IMPLICATIONS: This study describes the effect of different anesthetic techniques on the recovery of two different muscle relaxants, cisatracurium and rocuronium, when administered as either a single bolus or prolonged infusion during neurosurgery. This study demonstrates the feasibility of using these relaxants for these prolonged procedures.

Androstanols↗

PubMedDate not supplied

Recovery from sevoflurane anesthesia in horses: comparison to isoflurane and effect of postmedication with xylazine.

OBJECTIVE: To compare recovery from sevoflurane or isoflurane anesthesia in horses. STUDY DESIGN: Prospective, randomized cross-over design. ANIMALS: Nine Arabian horses (3 mares, 3 geldings, and 3 stallions) weighing 318 to 409 kg, 4 to 20 years old. METHODS: Horses were anesthetized on three occasions with xylazine (1.1 mg/kg), Diazepam (0.03 mg/kg intravenously [i.v.]), and ketamine (2.2 mg/kg i.v.). After intubation, they were maintained with isoflurane or sevoflurane for 90 minutes. On a third occasion, horses were maintained with sevoflurane and given xylazine (0.1 mg/kg i.v.) when the vaporizer was turned off. Horses were not assisted in recovery and all recoveries were videotaped. Time to extubation, first movement, sternal, and standing were recorded as was the number of attempts required to stand. Recoveries were scored on a 1 to 6 scoring system (1 = best, 6 = worst) by the investigators, and by three evaluators who were blinded to the treatments the horses received. These blinded evaluators assessed the degree of ataxia present at 10 minutes after each horse stood, and recorded the time at which they judged the horse to be ready to leave the recovery stall. RESULTS: Mean times (+/- SD) to extubation, first movement, sternal, and standing were 4.1 (1.7), 6.7 (1.9), 12.6 (4.6), and 17.4 (7.2) minutes with isoflurane; 3.4 (0.8), 6.6 (3.1), 10.3 (3.1), and 13.9 (3.0) minutes with sevoflurane; and 4.0 (1.2), 9.1 (3.3), 13.8 (6.5), and 18.0 (7.1) with sevoflurane followed by xylazine. Horses required a mean number of 4 (2.3), 2 (0.9), and 2 ( 1.6) attempts to stand with isoflurane, sevoflurane, and sevoflurane followed by xylazine respectively. The mean recovery score (SD) for isoflurane was 2.9 (1.2) from investigators and 2.4 (1.1) from blinded evaluators. For sevoflurane, the mean recovery score was 1.7 (0.9) from investigators and 1.9 (1.1) from evaluators, whereas the recoveries from sevoflurane with xylazine treatment were scored as 1.7 (1.2) from investigators and 1.7 (1.0) from blinded evaluators. CONCLUSIONS: Recoveries appeared to vary widely from horse to horse, but were significantly shorter with sevoflurane than isoflurane, although sevoflurane followed by xylazine was no different from isoflurane. Under the conditions of the study, recoveries from sevoflurane and sevoflurane followed by xylazine were of better quality than those from isoflurane. CLINICAL RELEVANCE: Sevoflurane anesthesia in horses may contribute to a shorter, safer recovery from anesthesia.

Adjuvants, Anesthesia↗

PubMed1993

pH recovery from intracellular alkalinization in Retzius neurones of the leech central nervous system.

1. Neutral-carrier pH-sensitive microelectrodes were used to investigate intracellular pH (pHi) recovery from alkalinization in leech Retzius neurones in Hepes- and in CO2-HCO3(-)-buffered solution. The Retzius neurones were alkaline loaded by the addition and subsequent removal of 16 mM acetate, by changing from 5% CO2-27 mM HCO3- to 2% CO2-11 mM HCO3- or by changing from CO2-HCO3(-)- to Hepes-buffered solution. 2. In Hepes-buffered solution (pH 7.4) the mean pHi was 7.29 +/- 0.11 and the mean membrane potential -44.7 +/- 5.9 mV (mean +/- S.D.; n = 83). 3. The rate of pHi recovery from alkalinization increased with decreasing pH of the bathing medium (pHb). pHi changed about 0.30 pH units for a pHb unit change. 4. A decrease of extracellular buffer concentration (Hepes concentration lowered from 20 to 5 mM) caused an acidification of extracellular and intracellular pH and an acceleration of pHi recovery from alkalinization. 5. A depolarization of the Retzius cell membrane-induced by increasing the K+ concentration of the bathing medium from 4 to 20 mM (delta Em = 16.5 +/- 5.5 mV) or from 4 to 40 mM (delta Em = 24.8 +/- 3.5 mV)--evoked a decrease of pHi and an acceleration of pHi recovery from alkalinization. 6. The H+ current blocker Zn2+ (0.5 mM) inhibited pHi recovery from alkalinization at resting membrane potential as well as during depolarization. The inhibition was more pronounced during depolarization. 7. In Cl(-)-free, CO2-HCO3(-)-buffered solution pHi recovery from an alkaline load by changing from 5% CO2-27 mM HCO3- to 2% CO2-11 mM HCO3- was slowed by 48-71%. The rate of pHi recovery from an alkaline load induced by changing from CO2-HCO3- to Hepes buffer was reduced by 33-56% in Cl(-)-free solution. The removal of external Cl- did not affect pHi recovery in Hepes-buffered solution. 8. The pHi recovery from alkalinization was DIDS-insensitive in CO2-HCO3(-)- as in Hepes-buffered solutions and was not slowed in the absence of external Na+. 9. It is concluded that in Retzius neurones pHi recovery from alkalinization is mediated by a passive voltage-dependent H+ influx along the electrochemical proton gradient. In the presence of CO2-HCO3- buffer a DIDS-insensitive Cl(-)-HCO3- exchanger additionally regulates pHi after an intracellular alkaline load. It cannot be excluded that intracellular processes (e.g. H+ release from organelles, metabolic H+ production) are also involved in pHi recovery from alkalinization.

Alkalies↗