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PubMed2002

Neurological and functional status 1 year after acute spinal cord injury: estimates of functional recovery in National Acute Spinal Cord Injury Study II from results modeled in National Acute Spinal Cord Injury Study III.

OBJECT: In the second National Acute Spinal Cord Injury Study (NASCIS II) investigators evaluated several standard neurological parameters but not functional activity. This has led to questions concerning the clinical importance of the increase in neurological recovery observed following administration of methylprednisolone (MP) within 8 hours of acute spinal cord injury (SCI). The safety of the therapy has also been questioned. METHODS: Both neurological and functional recovery were assessed in NASCIS III, a trial that followed an almost identical protocol to NASCIS II. In the current analysis locally weighted scatterplot smoothing (LOESS) nonparametric regression is used to model the extent of recovery in the Functional Independence Measure (FIM) that is predicted by improvement in the NASCIS/American Spinal Cord Injury Association motor scores that were documented in NASCIS III 1 year after SCI, and the models are applied to the extent of motor recovery demonstrated in NASCIS II. The models predict improvement in FIM that would be expected from the motor function recovery observed in NASCIS II. Estimates are provided overall and for patients with complete and incomplete neurological loss at time of injury. The authors review recent evidence obtained from randomized studies documenting adverse effects that may result from high-dose MP therapy. The relationship between motor function and FIM is strongly nonlinear and dependent on initial level of injury and degree of injury severity. In the best statistical model, the expanded motor score could be used to explain 77.2% of the variability in the FIM. Based on the mean MP-related 3.6-unit improvement in the motor score for patients with complete injuries and 7.3 for those with incomplete injuries owed to MP in NASCIS II, 18.6% of patients would improve six or more FIM points and 9% nine or more points, respectively. In those with complete neurological injury, the mean motor improvement of 3.6 predicted that 63.9% of the patients would improve three or more FIM points and 12.1% six or more points to a maximum of eight points. Of those with incomplete neurological injury, a 7.3 mean improvement in motor function predicted that 27.4% would gain six or more FIM points and that 21% would gain nine or more points to a maximum of 15 points. Analysis of the current best evidence from SCI and other randomized surgical trials in which high-dose MP has been administered provides no grounds for concern about commonly studied adverse effects. CONCLUSIONS: The extent of MP therapy-related motor function recovery observed in NASCIS II predicted clinically important recovery in the FIM. Reasons to be cautious with regard to this prediction include the lack of robustness in statistical modeling, some loss of validity in the FIM, and considerable heterogeneity in the SCI population. Whatever functional activity is ascribed to high-dose MP therapy, it is does not appear to be associated with risk of adverse outcomes.

Activities of Daily Living↗

PubMed1999

Stroke. Neurologic and functional recovery the Copenhagen Stroke Study.

Neurologic and functional recovery is dependent on a large variety of factors such as initial stroke severity, body temperature and blood glucose in the acute phase of stroke, stroke in progression, and treatment and rehabilitation on a dedicated stroke unit. The most important factor for recovery remains the initial severity of the stroke. In unselected patients 19% of the strokes are very severe, 14% are severe, 26% are moderate, and 41% are mild. In survivors, neurologic impairment after completed rehabilitation is still severe or very severe in 11%, moderate in 11%, mild in 47%, and 31% have achieved normal neurologic function. The ability to perform basic activities of daily living initially is reduced in three out of four patients with stroke. Most often affected is the ability to transfer, dress, and walk. After completed rehabilitation the group with moderate and severe disability is reduced from 50% to 25%, and the group with mild or no disability is increased from 50% to 75%. The prognosis of patients with mild or moderate stroke generally is excellent. Patients with severe stroke have a very variable recovery. Although the prognosis of patients with the most severe stroke is generally poor, one third of the survivors in this group are able to be discharged back to their own homes with no or only mild disability, if rehabilitated on a dedicated stroke unit. Functional recovery generally was completed within 3 months of stroke onset. Patients with mild stroke, however, recover within 2 months, patients with moderate stroke within 3 months, patients with severe stroke within 4 months, and patients with the most severe strokes have their functional recovery within 5 months from onset. Functional recovery is preceded by neurologic recovery by a mean of 2 weeks.

Activities of Daily Living↗

PubMed1998

The effect of exercise training on functional recovery after sciatic nerve crush in the rat.

Two separate experiments were carried out in order to evaluate the influence of moderate swim training and treadmill running on the rate of recovery of sensorimotor function following sciatic nerve injury in the rat. Nerve injury was induced by sciatic nerve crush. In the first experiment, rats were subjected to swim exercise (180 m daily), either for 7 days before, or for 14 consecutive days after nerve injury. In the second experiment rats were exercised on a motor driven treadmill device (10 m/min for 30 min twice daily) for 21 days. The recovery from nerve injury was assessed by means of an analysis of the free walking pattern (motor function) and the foot withdrawal reflex (sensory function) by electrical stimulation. The swim training program before or after crush did not affect the recovery of locomotor or sensory function. Treadmill running significantly deteriorated the gradual return of motor function (p < 0.05), but did not influence sensory recovery. We conclude that swim training does not interfere with functional sensorimotor recovery after sciatic nerve injury, and that a mild program of treadmill running retards recovery. We hypothesize that the retardation of recovery as a result of treadmill running is the consequence of the stress inflicted by the negative reinforcement used in the treadmill, or due to the severity of the training. /Ø?>

Animals↗

PubMed2000

[Immediate anesthesia recovery and psychomotor function of patient after prolonged anesthesia with desflurane, sevoflurane or isoflurane].

OBJECTIVE: To compare the anesthetic maintenance and early postoperative recovery and psychomotor function in patients who have been anesthestized with desflurane, sevoflurane or isoflurane during prolonged open urological surgery. PATIENTS AND METHODS: Seventy-five patients were randomly assigned to receive desflurane, sevoflurane or isoflurane with N2O 60% for anesthetic maintenance. The concentration of each drug was adjusted to maintain arterial pressure and heart rate +/- 20% of baseline. After the operation the anesthetics were discontinued and times until eye opening, spontaneous breathing, extubation and orientation were recorded. In the post-anesthesia recovery ward we applied the Newman-Trieger and Aldrete tests and recorded instances of nausea and vomiting and need for analgesia during the first 24 hours after surgery. RESULTS: The groups were similar with regard to demographic features, anesthetic maintenance, duration of anesthesia and relative doses of the anesthetics used. Recovery times in the operating room were significantly shorter (p < 0.05) after anesthesia with desflurane and sevoflurane than with isoflurane, with no significant differences between the desflurane and sevoflurane groups (duration of anesthesia 198 +/- 90, 171 +/- 67 and 191 +/- 79; eye opening 7.6 +/- 3.7, 7.8 +/- 3.0 and 11.9 +/- 4.5; time until extubation 7.8 +/- 3.0, 8.3 +/- 3.0 and 11.0 +/- 3.5 for desflurane, sevoflurane and isoflurane, respectively; all data in minutes). Recovery in the post-anesthetic recovery ward was similar for all three groups. CONCLUSIONS: Anesthetic maintenance was comparable with all three drugs. Desflurane and sevoflurane demonstrated advantages over isoflurane during recovery from anesthesia in the operating theater. No significant differences were found in psychomotor recovery, nausea and/or vomiting or requirements for postoperative analgesia.

Adult↗

PubMed2001

Postoperative nausea and vomiting in the recovery room. A report from Guyana.

Postoperative nausea and vomiting (PONV) in patients in the recovery room can delay transfer of such patients to the wards, preventing a smooth inflow of patients into the recovery area. The high incidence of these complications in developed countries has led to the introduction of management strategies that may be too expensive for developing countries. An investigation of the incidence and factors associated with PONV in the recovery room of the Public Hospital, Georgetown, Guyana, was undertaken with a view to developing an approach to its management based on local data. Seven hundred and sixty patients were studied. The majority (97%) had general anaesthesia. Simple anaesthetic techniques involving agents of relatively low cost were used. Anti-emetics were infrequently administered. Only twenty-two patients (2.9%) experienced PONV in the recovery room, all after general anaesthesia. Twenty-one of these (95%) had risk factors for PONV in their history. PONV in the recovery room was associated with female gender, gynaecological surgery, extra-abdominal surgery and lack of anti-emetic medication (p < 0.05), as well as prolonged duration of recovery room stay (p < 0.01). A management strategy for PONV in the recovery room involving continued use of present anaesthetic agents, increased use of inexpensive anti-emetic drugs currently available in Guyana, and targeting of patients found to be more at risk is suggested. Increased regional techniques may also be appropriate.

Adolescent↗

PubMed2001

Restoration of vision IV: role of compensatory soma swelling of surviving retinal ganglion cells in recovery of vision after optic nerve crush.

PURPOSE: Diffuse axonal injury following partial optic nerve crush (ONC) leads to severe visual deficits from which rats can partially recover within 2-3 weeks. To evaluate tbc role of surviving retinal ganglion cells (RGCS) in recovery, we have observed their morphology repeatedly in vivo with ICON-microscopy and correlated cell size changes with recovery of vision which we observed in parallel in the same animals. METHODS: After rats had learned a visual contrast discrimination task using an automated, computer-based test, RGCs were labeled retrogradely with fluorescent beads. Animals then received either no lesion, a complete axotomy or bilateral mild, moderate or severe ONC. Before surgery and for 40 days post-operatively, ROC number and soma size was repeatedly quantified every five days with tbc in vivo confocal neuroimaging method (Sabel et al., Nature med. 3, 1997, p. 244). In parallel, visual function was quantified with the contrast-discrimination task. RESULTS: After ONC about 70 % of the ROCs died after having undergone a fast and massive soma swelling. The extent of cell death was independent of crush severity. RGCs surviving the injury did not change their body size over time in the severe group and these animals also did not recover their vision. In contrast, after a mild or moderate crush, about half of the surviving RGCs experienced a slow and moderate, "compensatory" cell soma swelling and the rats showed partial recovery of vision. Both the number of RGCs showing such compensatory soma swelling and the extent of the swelling correlated highly (r = 0.96) with recovery of contrast discrimination performance at post-operative days 23 and 38. CONCLUSIONS: Depending en the time course and extent, soma swelling after neurotrauma may be associated either with cell death or recovery of function. Because of the very high correlation between extent of recovery and amount of soma swelling, moderate soma swelling contributes in a prominent way to recovery of vision. We believe that these cells provide an important structural substrate for neuronal tissue repair and therefore term these cells "compensatory neurons".

Adaptation, Physiological↗

PubMed2002

Different mechanisms for loss and recovery of binocularity in the visual cortex.

Diverse molecular mechanisms have been discovered that mediate the loss of responses to the deprived eye during monocular deprivation. cAMP/Ca2+ response element-binding protein (CREB) function, in particular, is thought to be essential for ocular dominance plasticity during monocular deprivation. In contrast, we have very little information concerning the molecular mechanisms of recovery from the effects of monocular deprivation, even though this information is highly relevant for understanding cortical plasticity. To test the involvement of CREB activation in recovery of responses to the deprived eye, we used herpes simplex virus (HSV) to express in the primary visual cortex a dominant-negative form of CREB (HSV-mCREB) containing a single point mutation that prevents its activation. This mutant was used to suppress CREB function intracortically during the period when normal vision was restored in two protocols for recovery from monocular deprivation: reverse deprivation and binocular vision. In the reverse deprivation model, inhibition of CREB function prevented loss of responses to the newly deprived eye but did not prevent simultaneous recovery of responses to the previously deprived eye. Full recovery of cortical binocularity after restoration of binocular vision was similarly unaffected by HSV-mCREB treatment. The HSV-mCREB injections produced strong suppression of CREB function in the visual cortex, as ascertained by both DNA binding assays and immunoblot analysis showing a decrease in the expression of the transcription factor C/EBPbeta, which is regulated by CREB. These results show a mechanistic dichotomy between loss and recovery of neural function in visual cortex; CREB function is essential for loss but not for recovery of deprived eye responses.

Animals↗

PubMed2002

Clinical recovery time from conscious sedation for dental outpatients.

For dental outpatients undergoing conscious sedation, recovery from sedation must be sufficient to allow safe discharge home, and many researchers have defined "recovery time" as the time until the patient was permitted to return home after the end of dental treatment. But it is frequently observed that patients remain in the clinic after receiving permission to go home. The present study investigated "clinical recovery time," which is defined as the time until discharge from the clinic after a dental procedure. We analyzed data from 61 outpatients who had received dental treatment under conscious sedation at the Hiroshima University Dental Hospital between January 1998 and December 2000 (nitrous oxide-oxygen inhalation sedation [n = 35], intravenous sedation with midazolam [n = 10], intravenous sedation with propofol [n = 16]). We found that the median clinical recovery time was 40 minutes after nitrous oxide-oxygen sedation, 80 minutes after midazolam sedation, and 52 minutes after propofol sedation. The clinical recovery time was about twice as long as the recovery time described in previous studies. In a comparison of the sedation methods, clinical recovery time differed (P = .0008), being longer in the midazolam sedation group than in the nitrous oxide-oxygen sedation group (P = .018). These results suggest the need for changes in treatment planning for dental outpatients undergoing conscious sedation.

Adolescent↗

PubMed2004

[Functional recovery and return to work in the young patient after a stroke].

INTRODUCTION: There are few works that study the functional recovery of young patients after suffering cerebrovascular disease (CVD) and even fewer works that study work reincorporation. Our aim is to evaluate these two aspects in the middle term in the young adults who have suffered a stroke and also to establish the factors that can influence a better prognosis. PATIENTS AND METHODS: Our work is a cross-sectional descriptive study of 111 patients aged between 15 and 55 years who have been discharged from our Hospital with a CVD diagnosis during the years 1999-2000. We have collected the following data from the clinical records: age, gender, type, location and reason for the CVD, vascular risk factors, complications in the process, with or without rehabilitation treatment and treatment description. By means of telephone interview, we obtained functional recovery with the Barthel Index (BI) and Modified Rankin Scale (MRS) as well as study level, marital status and pre and poststroke labor situation, loss of friends, loss of recreational activities and finally, sequels after the discharge. RESULTS: Functional recovery for daily activities (IB >or= 90) was good in 78 % of the patients, this being 72.1 % if we assess their global handicap (MRS <or= 2). Almost 80 % of the patients were working before the stroke, however, this decreased to only 50.2 % after the stroke. We have observed better functional recovery and return to work in ischemic stroke and in patients without vascular risk factors, in both cases without statistical significance (SS). We discovered an inverse relationship between age and functional recovery, measured by IB and a direct relationship with MRS, both of them with SS. We have also found SS between IB and the MRS and in those patients who returned to work compared to those who remained in an invalid situation. A total of 22.5 % of the patients reported loss of friends after the stroke, and there was SS in those who presented worst functional recovery. Finally, 57 % left previous recreational activities, there being no change in the marital status in most of the cases. CONCLUSIONS: Three quarter of cases achieved good functional recovery with reincorporation to work in half of the patients. Sociofamiliar integration was acceptable. As predictors of a good prognosis, we found subarachnoid hemorrhage, absence of vascular risk factors and low age when the stroke occurred.

Adolescent↗

PubMed2004

The predictive value of cortical activation by passive movement for motor recovery in stroke patients.

PURPOSE: Contralateral primary sensori-motor cortex (SM1) activation by passive movement was investigated by functional MRI (fMRI) at the early stage of stroke, to determine whether SM1 activation can be used to predict the degree of motor recovery of the hemiplegic hand. METHODS: We studied 17 stroke patients who showed complete paralysis of a hemiplegic hand at onset. The motor function of the hemiplegic hand was assessed on 4 separate occasions (at onset, at fMRI evaluation (performed < 4 weeks after onset), and 3 and 6 months after onset). Significant motor recovery was defined as recovery of the affected hand to the extent of it being able to prehend an object against gravity at least at 6 months after onset. RESULTS: The patients having an activated contralateral SM1 showed better motor recovery than those who did not. Only a fourth of the patients with an activated contralateral SM1 experienced a significant motor recovery, whereas none of the patients with an inactivated SM1 showed an improvement 6 months after onset, however, the incidence of significant motor recovery was not significantly difference between the two groups. CONCLUSION: It appears that contralateral SM1 activation by passive movement in the early stage of stroke has a low predictive value for the motor recovery of the hemiplegic hand, because the activation of the contralateral SM1 by passive movement appears to be mediated by somatosensory input to the cortex from the thalamus rather than from the motor pathway.

Adult↗

PubMed2005

Patterns of sensory recovery in the lingual nerve after surgical trauma.

OBJECTIVE: To examine the pattern of sensory recovery in the lingual nerve following injury, with an emphasis on qualitative changes. METHODS: Using data from one patient with prolonged dysaesthesia after surgical trauma to the lingual nerve, we correlated changes in perceived sensory function during recovery with results from qualitative and quantitative taste tests, and patient-reported quality-of-life measures. RESULTS: Recovery of quantitative taste testing as measured by automated electrogustometry, and qualitative whole of mouth taste testing, preceded perceptual recovery of taste. On the other hand, taste acuity as measured by regional qualitative taste testing tended to lag behind perceptual recovery. The pattern of recovery in the different qualitative taste sensations suggests variation in sensitivity of the nerve fibres responsible for carrying taste sensation, with the fibres relating to bitter and sour taste being the last to recover. CONCLUSION: To our knowledge, taking into account the limitations of this study, this picture of differential recovery of taste function in the lingual nerve has not been previously reported.

Electrodiagnosis↗

PubMed2005

Cortical reorganization associated lower extremity motor recovery as evidenced by functional MRI and diffusion tensor tractography in a stroke patient.

PURPOSE: Recovery mechanisms supporting upper extremity motor recovery following stroke are well established, but cortical mechanism associated with lower extremity motor recovery is unknown. The aim of this study was to assess cortical reorganization associated with lower extremity motor recovery in a hemiparetic patient. METHODS: Six control subjects and a 17 year-old woman with left intracerebral hemorrhage due to an arterio-venous malformation rupture were evaluated. The motor function of the paretic (left) hip and knee had recovered slowly to the extent of her being able to overcome gravity for 10 months after the onset of stroke. However, her paretic upper extremity showed no significant motor recovery. Blood oxygenation level dependent (BOLD) functional MRI at 1.5 Tesla was used to determine the acutual location of cortical activation in the predefined regions of interest. Concurrently, Diffusion Tensor Imaging (DTI) in combination with a novel 3D-fiber reconstruction algorithm was utilized to investigate the pattern of the corticospinal pathway connectivity between the areas of the motor stream. All subjects' body parts were secured in the scanner and performed a sequential knee flexion-extension with a predetermined angle of 0-60 degrees at 0.5 Hz. RESULTS: Controls showed anticipated activation in the contralateral sensorimotor cortex (SM1) and the descending corticospinal fibers stemming from motor cortex. In contrast to control normal subjects, the stroke patient showed fMRI activation only in the unaffected (right) primary SM1 during either paretic or nonparetic knee movements. DTT fiber tracing data showed that the corticospinal tract fibers were found only in the unaffected hemisphere but not in the affected hemisphere. CONCLUSIONS: Our results indicate that an ipsilateral motor pathway from the unaffected (right) motor cortex to the paretic (right) leg was present in this patient. This study raises the potential that the contralesional (ipsilateral) SM1 is involved in cortical reorganization associated lower extremity motor recovery in stroke. This study is the first neuroimaging evidence that the combined fMRI and DTI fiber tracing can significantly expand the explanatory power of probing cortical reorganization underlying motor recovery mechanism in stroke.

Adolescent↗

PubMed2006

Is there a trade-off between cognitive and motor recovery after traumatic brain injury due to competition for limited neural resources?

The status of neurorehabilitation for traumatic brain injury (TBI) is under active debate because of a dearth of research findings demonstrating effectiveness. This may be due, in part, to limitations in our understanding of basic mechanisms of cognitive and motor recovery,including those that might impede recovery. In this regard, we examined whether overall recovery following TBI might be undermined by competition between cognitive and motor functions for finite neural resources during recovery. In this preliminary study, 21 moderately and severely impaired patients were administered cognitive and motor assessments at 1, 4, and 12 months post-TBI, and recovery of cognitive and motor functions was measured using regression residuals. Negative correlations between recovery of cognitive versus motor functions were used as the index of competition. We found suggestive evidence that there may indeed be a trade-off between the recovery of cognitive and motor functions after TBI. Implications for rehabilitation are discussed.

Adult↗

PubMed1995

Postoperative hypoxaemia during transport and in the recovery area.

This study was undertaken to ascertain the incidence of postoperative hypoxaemia in the recovery area and during transfer to the recovery area while adhering to the current practice of anaesthesia and recovery room care. Attempts were also made to determine some of the risk factors for the development of hypoxaemia. There were 546 patients who had general or regional anaesthesia observed in the recovery area and of these, 534 patients were also observed during transfer using Critikon Oxyshuttle pulse oximeters. The incidence of hypoxaemia (SpO2 < or = 90%) and severe hypoxaemia (SpO2 < or = 85%) during transfer were 10.11% and 2.06% respectively. The incidence of hypoxaemia and severe hypoxaemia in the recovery area were 8.42% and 2.2% respectively. No oxygen was given to patients during transfer. In the recovery area, 322 patients (58.97%) had oxygen therapy and 224 patients (41.03%) did not. The occurrence of hypoxaemia during transfer was significantly related to the duration of surgery. In the recovery area, age and weight were found to be statistically significant risk factors. The incidence of hypoxaemia in this study is much lower than that reported in other studies.

Abdomen↗

PubMed2005

Initial patterns of clinical care and recovery from whiplash injuries: a population-based cohort study.

BACKGROUND: Little is known about the most effective pattern of clinical care for acute whiplash. We designed a cohort study to determine whether patterns of early clinical care (involving visits to general practitioners, chiropractors, or specialists) were associated with different rates of recovery. METHODS: We studied 2486 Saskatchewan adults with whiplash injuries. We defined 8 initial patterns of care that integrated type of provider and number of visits. We used multivariable Cox models to estimate the association between patterns of care and time to recovery while controlling for injury severity and other confounders. RESULTS: There was an independent association between the type and intensity of initial clinical care and time to recovery. We found that patients in the low-utilization general practitioner group had the fastest recovery, even after controlling for injury severity and other confounders. Compared with this group, the high-utilization general practitioner group experienced a 1-year rate of recovery that was 27% slower (adjusted hazard rate ratio [HRR], 0.73; 95% confidence interval [CI], 0.61-0.87); for the high-utilization chiropractic group it was 39% slower (HRR, 0.61; 95% CI, 0.46-0.81); for the high-utilization general practitioner plus chiropractic combined group it was 28% slower (HRR, 0.72; 95% CI, 0.57-0.91); and for those who consulted general practitioners and specialists, it was 31% slower (HRR, 0.69; 95% CI, 0.55-0.87). CONCLUSIONS: The type and intensity of clinical care initiated within the first month after the injury is associated with the rate of recovery from whiplash injuries. Our study does not support the hypothesis that early aggressive care promotes faster recovery.

Adult↗

PubMed1998

Recovery of neglect after right hemispheric damage: H2(15)O positron emission tomographic activation study.

BACKGROUND: The neural correlates of recovery of unilateral neglect (ULN), as well as of other consequences of focal brain damage, are largely unknown. Functional neuroimaging methods (in particular, positron emission tomography [PET]) can be applied to the in vivo study of recovery mechanisms in neurologic patients. OBJECTIVE: To evaluate the functional cerebral correlates of recovery from ULN in patients with right-sided lesions, with the use of a PET activation paradigm. METHODS: Study of 3 patients with cerebrovascular lesions that involved corticosubcortical (patient 1) or subcortical (patients 2 and 3) areas of the right hemisphere. Unilateral neglect was tested twice, before and after completion of a 2-month rehabilitation program, after which all 3 patients showed considerable improvement. Similarly, 2 PET examinations were performed, before and after recovery, during the performance of a visuospatial task requiring the patients to detect and respond to visual targets moving on a computer screen from the right to the left visual hemifield (experimental condition). The cerebral activation was compared with a baseline task in which subjects responded to a black dot flashing in a fixed position of the right hemifield. RESULTS: The brain areas activated by the performance of the visuospatial task before and after recovery were compared. In all 3 patients, the regions notably more active after recovery were almost exclusively found in right-sided cortical areas and largely overlapped with those observed in a group of 4 normal subjects performing the same task. Other areas, which have been shown to be involved in attentional and oculomotor tasks in other PET studies, were also activated in patients with ULN. CONCLUSIONS: The behavioral recovery of ULN in these patients with predominantly subcortical lesions is mainly associated with cerebral activations in cortical regions similar to those observed in normal subjects. There is some evidence of functional reorganization in individual subjects, which involves other areas related to space representation and exploration.

Aged↗

PubMed1999

Efficient and economical recovery of poly(3-hydroxybutyrate) from recombinant Escherichia coli by simple digestion with chemicals.

A simple method for the recovery of microbial poly(3-hydroxybutyrate) [P(3HB)] from recombinant Escherichia coli harboring the Ralstonia eutropha PHA biosynthesis genes was developed. Various acids (HCl, H2SO4), alkalies (NaOH, KOH, and NH4OH), and surfactants (dioctylsulfosuccinate sodium salt [AOT], hexadecyltrimethylammonium bromide [CTAB], sodium dodecylsulfate [SDS], polyoxyethylene-p-tert-octylphenol [Triton X-100], and polyoxyethylene(20)sorbitan monolaurate [Tween 20]) were examined for their ability to digest non-P(3HB) cellular materials (NPCM). Even though SDS was an efficient chemical for P(3HB) recovery from recombinant E. coli, it is expensive and has waste disposal problem. NaOH and KOH were also efficient and economical for the recovery of P(3HB), and therefore, were used to optimize digestion condition. When 50 g DCW/L of recombinant E. coli cells having the P(3HB) content of 77% was treated with 0.2 N NaOH at 30 degrees C for 1 h, P(3HB) was recovered with purity of 98.5%. Using this simple recovery method, the effect of recovery method on the final production cost of P(3HB) was examined. Processes for the production of P(3HB) by recombinant E. coli from glucose with two different recovery methods, surfactant-hypochlorite digestion and simple digestion with NaOH, were designed and analyzed. By employing the fermentation process that resulted in P(3HB) concentration, P(3HB) content and P(3HB) productivity of 157 g/L, 77%, and 3.2 P(3HB) g/L-h, respectively, coupled with the recovery method of NaOH digestion, the production cost of P(3HB) was US$ 3.66/kg P(3HB), which was 25% less than that obtained by employing the surfactant-hypochlorite digestion method.

Alkalies↗

PubMed1996

ADP recovery after a brief ischemic exercise in normal and diseased human muscle--a 31P MRS study.

The pattern of cytosolic ADP recovery after exercise has not been fully characterized in human skeletal muscle. ADP recovery after brief, ischemic exercise was studied by 31phosphorus magnetic resonance spectroscopy in calf muscles of 33 normal control subjects, four patients with McArdle's disease and 13 patients with mitochondrial myopathy. In normal muscle, the half-time for the initial ADP decline was 0.18 +/- 0.07 min and was unaffected by the pH or the metabolic state at the end of exercise. ADP decreased to below rest values during the second min of recovery in 27 out of 33 control subjects. There was a significant (p < 0.001) linear correlation for both the size (r = 0.65) and duration (r = 0.64) of this ADP undershoot with intracellular pH. Phosphocreatine resynthesis continued during the ADP undershoot. ADP undershoot was also found in patients with mitochondrial diseases (in 11 out of 13), but not McArdle's disease (six patients). Thus ADP recovery follows a complex time course that is partly dependent on pH. Only the initial ADP recovery is independent of pH, which makes it suitable for comparative assessment of muscle mitochondrial function in vivo. As phosphocreatine recovery continues during the ADP undershoot, mitochondrial regulation must be different from that at the onset of recovery. These observations are consistent with variable, changing regulators of mitochondrial metabolism in human skeletal muscle.

Adenosine Diphosphate↗