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PubMed2004

Characteristics of recovery of adrenocortical function after treatment for Cushing's syndrome due to pituitary or adrenal adenomas.

OBJECTIVE: Surgical cure of Cushing's syndrome (CS) is followed by adrenocortical insufficiency, which may be long-lasting. The aim was to elucidate recovery of adrenocortical function, defined as a normal cortisol response to ACTH stimulation, and the relation to ACTH in patients cured for CS due to pituitary Cushing's disease (CD) or adrenal (AA) adenomas. DESIGN: A retrospective study including 32 patients considered surgically cured for CS (18 CD, 14 AA). RESULTS: Twelve (67%) patients with CD recovered within median 24 months (range 7 months-4(1)/(2) years) whereas six did not recover within 3-12 years. Plasma ACTH (p-ACTH) at time of recovery was not different from p-ACTH in patients not recovering (P = 0.9). Eleven (79%) patients with AA recovered within 24 months (10 months-4 years) whereas three did not recover within 4-10 years. p-ACTH at time of recovery was higher compared to patients not recovering (P < 0.04). No differences were observed comparing CD and AA patients concerning preoperative 24-h urinary free cortisol (UFC) excretion, postoperative unstimulated s-cortisol or recovery time. By contrast, p-ACTH measured at time of recovery was higher in AA compared to CD (median 12.3 vs. 4.6 pmol/l) (P < 0.001), whereas plasma dehydroepiandrosterone sulfate (p-DHEAS) was lower in AA compared to CD (median 300 vs. 1500 nmol/l) (P = 0.02). CONCLUSION: Recovery of secondary adrenal insufficiency is a slow process in both CD and AA. ACTH measured at time of recovery was significantly higher and DHEAS significantly lower in patients with AA compared to CD, which may suggest different mechanisms of the recovery process and different set points in the glucocorticoid feedback inhibition of ACTH secretion.

Adrenal Cortex↗

PubMed1986

The use of a model system to compare the efficiency of ultrasound and agitation in the recovery of Bacillus subtilis spores from polymer surfaces.

The effectiveness of ultrasound and mechanical agitation for the recovery of Bacillus subtilis spores from pre-inoculated glass, polystyrene, polypropylene, polyethylene and polycarbonate surfaces was tested in the presence and absence of surfactant. Recovery from polymers was improved by the use of surfactant. Simple agitation, as frequently used in bioburden determination, is shown to be a poor method for the recovery of spores from hard surfaces. The use of ultrasound achieves recoveries over 90% only with glass, recoveries from polymers ranging from 40%-75%. Recoveries from polypropylene and polycarbonate showed poor reproducibilities. Agitation with Ballotini beads improved the reproducibility of recoveries from polymers and also in the majority of cases improved recovery levels.

Bacillus subtilis↗

PubMed2000

Lactate, glucose and O2 uptake in human brain during recovery from maximal exercise.

The metabolic activity of the brain has not been evaluated during physical exercise. In six volunteers substrate uptake by the brain was determined during graded exercise and recovery from maximal exercise by measuring the arterial-internal jugular venous concentration differences(a-v differences). The a-v difference for lactate increased from 0.02 +/- 0.08 mmol l-1 at rest to 0.39 +/- 0. 13 mmol l-1 during exercise and remained positive during 30 min of recovery (P < 0.05). The a-v difference for glucose (0.55 +/- 0.06 mmol l-1 at rest) did not change significantly during exercise, but during the initial 5 min of recovery it increased to 0.83 +/- 0.10 mmol l-1 (P < 0.05). The O2 a-v difference at rest of 3.11 +/- 0.30 mmol l-1 remained stable during exercise, then increased during the initial 5 min of recovery (3.77 +/- 0.52 mmol l-1) and remained high during the subsequent 30 min recovery period (3.62 +/- 0.64 mmol l-1; P < 0.05). Thus the O2/glucose uptake ratio did not change during exercise (pre-exercise 5.95 +/- 0.68; post-exercise 6.02 +/- 1.39) but decreased to 4.93 +/- 0.99 during the initial 5 min of recovery (P < 0.05). When lactate uptake was included, the resting O2/carbohydrate uptake ratio of 5.84 +/- 0.73 was reduced to 4.42 +/- 0.25 during exercise and decreased further during the recovery phase (to 3.79 +/- 0.30; P < 0.05). In contrast, in the resting and immobilised rat, lactate infusion to a level similar to that obtained during maximal exercise in humans did not affect the a-v difference for lactate. The large carbohydrate uptake by the brain during recovery from maximal exercise suggests that brain glycogen metabolism is important in the transition from rest to exercise, since this would explain the significant post-exercise decrease in the O2/carbohydrate uptake ratio.

Adult↗

PubMed1991

Staurosporine inhibits the extent of acetylcholine receptor recovery from carbachol-induced desensitization in snake twitch fibres.

1. The effect of the protein kinase inhibitor, staurosporine, on the extent and time course of recovery following carbachol-induced desensitization was studied in snake twitch-muscle fibres maintained in an isotonic potassium propionate solution and voltage-clamped to +30 mV. 2. Pretreatment with staurosporine (0.5 microM) decreased the extent of recovery of spontaneous miniature endplate current (m.e.p.c.) amplitudes following desensitization by a sustained application of 540 microM carbachol. Recovery was inhibited by approximately 50% without altering the time course of m.e.p.c. recovery. 3. Staurosporine also produced a concentration-dependent (10 nM to 0.5 microM) decrease in the amplitude of a second carbachol-induced current, following a wash period, as compared to the amplitude of the current produced by the initial carbachol application. Pretreatment with 0.5 microM K252a, another wide spectrum protein kinase inhibitor, also decreased the extent of recovery of the response to a second carbachol application following desensitization. 4. Staurosporine pretreatment (0.5 microM) had no effect on either the kinetics of receptor-channel gating or the initial endplate sensitivity to agonist. This was determined by comparing the amplitude of the carbachol (540 microM)-induced currents and the amplitude and decay rate of m.e.p.cs in control and staurosporine-treated fibres. 5. Staurosporine had no effect on the time course of desensitization onset produced during the initial application of 540 microM carbachol or the depth of desensitization produced by the end of a 2-3 min exposure to 540 microM carbachol.6. Elevation of the external calcium concentration from 1 to 10mM during the 540 microM carbachol application completely antagonized the decreased extent of recovery of m.e.p.c. amplitude produced by pretreatment with 0.5 microM staurosporine.7. We suggest that phosphorylation of a population of acetylcholine receptors is required for complete recovery from desensitization, and that staurosporine inhibits the protein kinases responsible for this phosphorylation.8. We further propose that a transient increase in intracellular calcium, produced by an increase in calcium influx through agonist-activated endplate channels, stimulates additional protein kinase activity, which in turn, antagonizes the effect of staurosporine-treatment on recovery.

Alkaloids↗

PubMed1993

Mechanism of staurosporine-induced decrease in acetylcholine receptor recovery from desensitization.

1. Previously, we showed in voltage-clamped snake twitch muscle fibres that the extent of recovery of the nicotinic acetylcholine (ACh) receptor from carbachol-induced desensitization is reduced by pretreatment with the protein kinase inhibitor staurosporine. The present studies were undertaken to determine the mechanism underlying the staurosporine-induced inhibition of recovery. 2. Pretreatment with 0.5 microM staurosporine significantly decreased the extent of recovery of spontaneous miniature endplate current (m.e.p.c.) amplitudes in preparations exposed to 540 microM carbachol. The decrease in recovery of m.e.p.c. amplitude by staurosporine was dependent on the duration of carbachol exposure. No significant decrease in m.e.p.c. amplitude was observed with a 1 min exposure to agonist, whereas a significant decrease in recovery was seen with agonist exposures between 5-10 min. Further, the effect of staurosporine pretreatment on ACh receptor recovery was long-lasting such that m.e.p.c. amplitude remained decreased for at least 60 min. 3. Estimation of mean channel conductance by noise analysis during local perfusion of 20 microM carbachol demonstrated a decrease in conductance from 52 pS to 23 pS in staurosporine-treated preparations following recovery from desensitization. Staurosporine treatment in the absence of desensitization did not alter the mean channel conductance. 4. A single population of ACh-activated single channel currents with a conductance of 45-49 pS was recorded in cell-attached patches from enzymatically cleaned endplates in control and staurosporine-treated preparations not exposed to carbachol. 5. At staurosporine-treated endplates exposed to carbachol and then allowed to recover, a population of small conductance (23 pS) channels was observed. These channels were not normally seen in control preparations which had undergone carbachol-induced desensitization and recovery.6. We suggest that the decrease in m.e.p.c. amplitude observed following recovery from desensitization in staurosporine-treated endplates results from the activation of a mixture of small and large conductance ACh receptor channels.

Alkaloids↗

PubMed1993

Necessity of divalent cations for recovery from carbachol-induced nicotinic acetylcholine receptor inactivation at snake twitch fibre endplates.

1. Previous studies demonstrated that elevation of the extracellular calcium concentration during a prolonged exposure to a high concentration of carbachol reverses the staurosporine-induced decrease in the extent of endplate resensitization in voltage-clamped snake twitch fibres. The present studies were designed to establish the site, specificity and potential mechanisms by which calcium could reverse the effects of staurosporine on acetylcholine receptor recovery. 2. Pretreatment of potassium-depolarized muscle preparations with 0.5 microM staurosporine, followed by a 10 min incubation with 540 microM carbachol, produced a significant decrease in the recovery of miniature endplate current (m.e.p.c.) amplitudes. Raising the extracellular calcium concentration from 1 mM to 10 mM during the agonist application reversed this inhibition. In addition, a brief (3 min) incubation in an elevated calcium (10 mM) solution in staurosporine-treated preparations previously exposed to 540 microM carbachol also reversed the reduction in m.e.p.c. amplitude. 3. Substitution of calcium with 10 mM strontium had no effect on the staurosporine-induced decrease in m.e.p.c. amplitude, whereas 10 mM magnesium partially substituted for calcium. Inclusion of (+)-tubocurarine (13 microM) in the 10 mM calcium solution to prevent the influx of calcium through agonist-activated channels did not prevent the reversal of the staurosporine-induced decrease in m.e.p.c. amplitudes. This suggested that the site of action of calcium on endplate resensitization was extracellular. 4. Analysis of acetylcholine (ACh)-induced single channel currents demonstrated that a population of small conductance channels seen only in the staurosporine-treated preparations following carbachol exposure, was still present in staurosporine-treated preparations incubated in 540 microM carbachol solution containing 10 mM calcium. Thus the effect of calcium on ACh receptor recovery was not due to the conversion of the small conductance channels to the normal, large conductance channels.5. Removal of calcium from the extracellular solution with the magnesium concentration unchanged,resulted in no change in the extent of m.e.p.c. amplitude recovery, nor did it alter the ability of staurosporine to inhibit recovery. Removal of both calcium and magnesium resulted in a significant decrease in the extent of recovery and staurosporine produced no additional decrease. This decrease in m.e.p.c. recovery in the divalent cation-free solution was not associated with a change in mean channel conductance as determined by noise analysis.6. Based on the results from these experiments, we suggest that, with prolonged exposure to agonist,some ACh receptors at the endplate become irreversibly inactivated. For full recovery of endplate sensitivity to occur, inactivated ACh receptors must be replaced. Part of the replacement ACh receptors appear to be recruited from a readily available but not previously activated pool and this process is dependent on extracellular calcium and/or magnesium. Thus, elevation of extracellular calcium may be able to reverse the apparent decrease in endplate sensitivity in staurosporine-treated fibres following carbachol exposure by increasing the number of functional receptors at the endplate.

Alkaloids↗

PubMed1994

NMDA antagonists increase recovery of evoked potentials from slices of rat olfactory cortex after anoxia.

1. The role of glutamate in producing tissue damage during cerebral anoxia was investigated in brain slices using antagonists to the NMDA and AMPA receptor types. 2. Tissue function was assessed by field recordings of the synaptically evoked potentials elicited by stimulating the main afferent input to the olfactory cortex, the lateral olfactory tract. Anoxia was produced by bathing the slice in glucose-free solution equilibrated with 95% N2/5% CO2. 3. The amount of recovery of the evoked potential was inversely dependent on the period of anoxia and temperature: at 24 degrees C, 15 min of anoxia followed by reoxygenation produced a 14.6 +/- 4.1% recovery whereas there was no recovery at 35 degrees C. 4. Dizocilpine and ketamine had no effect on synaptic transmission in oxygenated media but following anoxia they produced an increased recovery of the responses: from 14.6 +/- 4.1% to 48.3 +/- 7.8% for dizocilpine (10 microM) and 21.6 +/- 7.7% to 87.2 +/- 7.1% for ketamine (200 microM); the tissue endurance to anoxia was increased by around 5 min. 5. Blockade of the AMPA receptors did not influence recovery in spite of the depressed synaptic transmission. A similar synaptic attenuation produced by lignocaine provided some increase in post-anoxic recovery. 6. The NMDA receptor antagonist, AP5, antagonized NMDA at 50 microM by 3.7 fold and at 200 microM by 15 fold but only 200 microM increased post-anoxic recovery. This suggests that a substantial degree of NMDA antagonist is required before anoxic tissue damage due to NMDA receptor activation can be nullified. The antagonist to the glycine binding site, 7-chlorokynurenic acid also increased recovery. 7. These in vitro experiments confirm the idea that NMDA receptor activation makes a substantial contribution to cerebral tissue damage and that this can be reduced by a substantial blockade of these receptors.

2-Amino-5-phosphonovalerate↗

PubMed1995

Effects of nicorandil on the recovery of reflex potentials after spinal cord ischaemia in cats.

1. The pathophysiological significance of ATP-sensitive K+ (KATP) channels in the central nervous system is not fully understood. In this study the effects of nicorandil (a hybrid vasodilator having a dual mechanism of action as a K+ channel opener and a nitrate) on the recovery of the spinal cord reflex potentials after spinal cord ischaemia were examined and compared with those of pinacidil and nitroprusside in anaesthetized spinal cats. 2. Spinal cord ischaemia was produced by occlusion of the thoracic aorta and the bilateral internal mammary arteries for 10 min. Regional blood flow in the spinal cord was continuously measured with a laser-Doppler flow meter. The monosynaptic (MSR) and polysynaptic reflex (PSR) potentials, elicited by electrical stimulation of the tibial nerve, were recorded from the lumbo-sacral ventral root. The recovery process of spinal reflex potentials was reproducible when the occlusion was repeated twice at an interval of 120 min. 3. Pretreatment with nicorandil (30-100 micrograms kg-1) accelerated the recovery of PSR potentials after spinal cord ischaemia. Such an accelerating effect on the recovery of PSR potentials was also shared by pinacidil (100 micrograms kg-1), another K+ channel opener. In addition, the accelerating effect of nicorandil (100 micrograms kg-1) on the recovery of PSR potentials was abolished by co-administration of glibenclamide (3 mg kg-1), a sulphonylurea KATP channel blocker. Nitroprusside (8 micrograms kg-1min-1) retarded rather than improved the recovery of PSR potentials after spinal cord ischaemia. All of these drugs failed to improve the spinal cord blood flow during ischaemia and reperfusion. 4 These results suggest that nicorandil promotes the recovery of polysynaptic reflex potentials after spinal cord ischaemia by opening the KATP channels of neurones rather than by increasing local bloodflow. K+ channel openers may exert a salutary effect on the functional recovery of the ischaemic spinal cord.

Animals↗

PubMed1994

Systolic arterial pressure recovery after ventricular fibrillation/flutter in humans.

Although the elective induction of cardiac arrest for implantable defibrillator insertion under general anesthesia is widely used, the hemodynamics of recovery of arterial blood pressure after cardiac arrest is not well-defined. Accordingly, the time course of recovery of systolic arterial pressure was studied in seven patients during the repetitive induction of ventricular fibrillation (n = 6) or ventricular flutter (n = 1). The mean number of episodes of cardiac arrest was 7 +/- 2, and the mean drop in systolic pressure was 84 +/- 16 mmHg. The mean recovery time for systolic pressure was 10 +/- 6 seconds, the average systolic pressure recovery rate was 13 +/- 14 mmHg/sec, and the mean percent systolic pressure recovery was 94% +/- 9%. A negative logarithmic relation was found to exist between the rate of systolic arterial pressure recovery and the duration of ventricular fibrillation or flutter with a correlation coefficient of 0.68 to 0.97 (P < 0.05) in five of the seven patients. A linear relation between the time for systolic pressure recovery and duration of asystole was also defined. These results are consistent with the view that prolongation of ventricular fibrillation or flutter increases the duration of arterial pressure recovery through a negative effect on left ventricular contractility. Increased understanding of these relations may lead to increased safety of implantable defibrillator insertion.

Adult↗

PubMed1995

Recovery and insight in schizophrenia.

A study sample of 50 patients suffering from schizophrenia was examined at readmission and thereafter every second week until each patient had been interviewed five times i.e. eight weeks in total. Three types of recovery are identified, one with full and two with partial recovery of delusional beliefs. In patients with full recovery, the delusional dimensions (conviction, extension and pressure) decrease in a parallel manner. In patients with partial recovery, decreases in pressure precede decreases in other dimensions. Two-thirds (64%) of the patients have high insight from the very start of admission, and for two-thirds (68%) the degree of insight does not change during recovery. The average degree of insight increases during recovery, irrespective of the type of recovery. It is concluded that insight operates to some degree independently of positive psychotic symptoms and may be perceived as a distinct component of recovery.

Adult↗

PubMed1984

Combined granulocyte and platelet transfusions: inter-relationship between granulocyte and platelet recoveries in the presence and absence of complicating factors.

191 combined collections of granulocytes (PMN) and platelets (PLT) obtained by discontinuous cytapheresis were given to 23 patients with acute myeloid leukaemia (AML). The circulation in recipients of the concomitantly transfused cells was compared by measuring the % recovery of PMN at 1 h, and of PLT at 1 and 20 h. The recovery of both cells was greatly reduced in transfusions accompanied by a transfusion reaction. Fever in recipients had no effect on the recovery of either cell, but PMN recovery was significantly higher in patients receiving oral prednisolone. Alloimmunization to PLT, defined as recovery levels less than 15% at 1 h and/or less than 10% at 20 h, was recorded in 42 transfusions, and PMN recovery was significantly reduced in this group. In transfusions where PMN recovery was 'low' (less than 5%); the recovery of the coincidentally transfused PLT was significantly reduced only in transfusions accompanied by a reaction. These results emphasize the deleterious effects of transfusion reactions and suggest that donor PMN frequently circulate less well in recipients alloimmunized to PLT from the same donor.

Blood Group Incompatibility↗

PubMed2005

Measuring surgical recovery: the study of laparoscopic live donor nephrectomy.

Following laparoscopic donor nephrectomy (LDN), recovery has only been studied using traditional outcomes, subjective and confounded by comorbidity and psychosocial variables. The purpose of this study is to estimate surgical recovery following LDN using standardized, validated instruments and to compare this recovery profile to that obtained with traditional measures. This was a prospective study of patients undergoing LDN at a single institution between September 2001 and January 2004 (n = 35). At baseline and 4 weeks following surgery, functional exercise capacity was measured using the 6-min walk test (6MWT) and health-related quality of life was assessed with the Short Form-36 (SF-36) questionnaire, including physical component summary (PCS) and mental component summary (MCS) scores. Patients' self-assessment of recovery and time to resumption of regular activities was ascertained. At follow-up (median 29 days), patients' 6MWT was lower by a median of 30 m (p = 0.07) and PCS decreased from 57.1 to 42.3 (p = 0.0001), whereas MCS remained constant. Overall, length of stay, return to activities and patient-stated recovery were inadequate outcomes for classifying patient recovery using 6MWT and PCS as the reference standards. Four weeks following LLDN, patients have returned to baseline exercise capacity, but not baseline general physical health. Traditional measures of recovery are incomplete descriptors of recovery.

Adult↗

PubMed1995

Sweating rate and sweat composition during exercise and recovery in ambient heat and humidity.

The objective of this study was to determine the composition and extent of sweat losses during submaximal exercise under hot and humid conditions and to compare these findings with the same exercise protocol conducted under cool, dry and hot, dry conditions. Five Thoroughbred horses (age 3 to 6) completed exercise tests under each of 3 environmental conditions in random order: cool, dry (CD), room temperature (T) = 20 degrees C, relative humidity (RH) = 45-55%; hot, dry (HD), T = 32-34 degrees C, RH = 45-55%; and hot, humid (HH), T = 32-34 degrees C, RH = 80-85%. Horses exercised at 50% of their predetermined VO2max on a treadmill set at a 10% slope until attainment of a pulmonary artery blood temperature of 41.5 degrees C followed by a 60 min recovery. Sweat was collected from a sealed polyethylene pouch enclosing a 150 cm2 area on the lateral thorax. During exercise and the first 30 min of recovery, sweat fluid losses were 7.9 +/- 0.7 litres, 9.9 +/- 0.5 litres and 6.6 +/- 1.2 litres (mean +/- s.e.m.) for CD, HD and HH, respectively. Sweating rate (SR), calculated from sweat volume per unit area of enclosed skin, was lowest in CD and similar in HD and HH during exercise such that at end of exercise in HH (16.5 min) calculated sweat losses were approximately 5% and 32% higher than in HD and CD, respectively. In recovery, SR declined in all conditions but was significantly lower in CD (P < 0.05). Sweating was detectable until 30 min recovery in CD, 45 min recovery in HD and 60 min recovery in HH. Sweat composition and osmolality was different under the 3 environmental conditions and changed gradually during exercise and recovery in all conditions. Osmolality and [Na] was highest in HD and lowest in CD. During exercise, [Na] increased with increasing SR. Although exercise duration was significantly decreased in HH (16.5 +/- 1 min) when compared to HD (28 +/- 2 min) and CD (37 +/- 2 min), fluid and ion losses in HH were comparable to those in HD as a result of a high SR and prolonged sweating during recovery.

Animals↗

PubMed1966

Recovery of responsiveness of cells of lateral geniculate nucleus of rat.

1. Recovery of responsiveness of single cells in lateral geniculate nucleus of rat has been determined in both P and I cells. There are three types of recovery curve among P cells; (a) early recovery, (b) early partial recovery followed by depression and then complete recovery, (c) prolonged depression followed by cyclic recovery. Type (c) is by far the commonest recovery curve. In contrast to the spike in a P cell, the synaptic potential recovers to its full amplitude in about 20 msec. All I cells exhibit similar rapid recovery curves after a prolonged depression.2. Conditioning stimuli applied to visual cortex also produce a prolonged depression in most P cells but I cells can be re-excited at short intervals from cortex. Decortication does not prevent the prolonged depression of the multineuronal response produced by optic nerve stimulation.3. A neuronal model is proposed to explain these observations. It is supposed that I cells (interneurones) are innervated by axon collaterals of the P cells (principal cells, projecting to visual cortex) and that the I cells exert an inhibitory influence on the P cells.

Animals↗

PubMed1988

Threshold recovery functions following impulse noise trauma.

An analysis of the pure-tone threshold recovery functions obtained from 118 chinchillas exposed to high-level impulse noise showed that there are at least three distinctly different types of recovery function: type I--a recovery function for which the initial threshold shift recovers monotonically with increasing postexposure time; type II--a delayed recovery; i.e., for a period as long as 6 h following removal from noise, the pure-tone threshold remains elevated and stable before thresholds begin to follow a monotonic course of recovery; and type III--the growth function; i.e., over a period of at least 6 h following removal from the noise, pure-tone thresholds continue to get worse before they begin to follow a monotonic course of recovery. There is more permanent threshold shift (PTS), more sensory cell loss, and predictions of PTS and cell loss based upon initial measures of threshold shift are less accurate at those frequencies characterized by a type III recovery process than at those frequencies characterized by a type I recovery process.

Acoustic Stimulation↗

PubMed1996

The effect of level and relative frequency region on the recovery of overshoot.

Overshoot--in particular, threshold for a signal near masker onset--can be reduced by presenting a stimulus (precursor) just prior to masker onset. The recovery of overshoot can be examined by varying the delay between the offset of the precursor and the onset of the masker, where "recovery" denotes an increase in the threshold for a signal near masker onset. The present study examined the effects of stimulus level and relative frequency region on this recovery. In all experiments, the masker was a broadband of noise and the signal was a 4-kHz sinusoid. The first experiment examined the effects of masker level on overshoot in order to choose two levels (one "low" and one "high") that produced similar amounts of overshoot; these levels were used in the remaining experiments. In the second experiment, the precursor was identical to the masker, and recovery functions were measured for both low and high masker and precursor levels. there was no consistent difference in the recovery functions between the two levels. In the third experiment, the precursor was divided into two bands (one below and one above 4 kHz); one was presented continuously while the other was gated as in experiment 2. The recovery was more complete when the band above 4 kHz was gated, although the recovery was usually less than that observed in experiment 2 when (effectively) both bands were gated. The results suggest that the frequency regions on both sides of the signal are important for the recovery of overshoot, but that the frequency region above the signal may be more important than the region below.

Adolescent↗

PubMed1980

Improved method and test strategy for recovery of enteric viruses from shellfish.

An improved recovery method and testing strategy were devised for recovery of low numbers of enteric viruses from each of three commercially important shellfish species. Effective recovery of virus depended as much upon details of the test strategy adopted for use of the improved method with each species as on the method itself. The most important test details involved sample composition, pool size, and method of use of cell cultures. Recovery sensitivity measured permitted detection of 25 to 3 plaque-forming units of enteroviruses and 100 to 27 plaque-forming units of reovirus through their recovery in cell culture, with effectivenesses averaging 64 and 46%, respectively. Test samples prepared by the improved recovery method were virtually cytotoxicity free. Optimal recovery of virus on 45-cm2 cell culture monolayers was obtained with 1-ml inocula adsorbed for 2 h. The most effective recovery of virus from shellfish samples was made by a sequential adsorption procedure which allowed equal exposure of an entire sample to each of two or more cell cultures. Removal of nonviral contaminants from test samples by antibiotic treatment was preferable to the use of ether or membrane filtration procedures.

Animals↗

PubMed1972

Thermal injury and recovery of Bacillus subtilis.

Exposure of Bacillus subtilis NCTC 8236 to sublethal temperatures produced a change in the sensitivity of the organism to salt and polymyxin. After 30 min at 47 C, 90% of the population was unable to grow on a modified sulfite polymyxin sulfadiazine agar containing an added 1% NaCl, 1% glucose, and 1% asparagine. The data presented demonstrate that thermal injury results in degradation of both 16S and 23S ribonucleic acid (RNA) and in damage to the cell membrane, suggested by leakage into the heating mestruum of material absorbing at 260 nm. When the cells were placed in a recovery medium (Trypticase soy broth), complete recovery, indicated by a returned tolerance to salt and polymyxin, occurred within 2 hr. The presence of a protein inhibitor (chloramphenicol) and cell wall inhibitors (vancomycin and penicillin) during recovery had no effect, whereas the presence of an RNA inhibitor (actinomycin D) effectively inhibited recovery. Further data demonstrated that the injured cells were able to resynthesize both species of ribosomal RNA during recovery by using the fragments which resulted from the injury process. Also, precursor 16S and precursor 23S particles accumulated during recovery. The maturation of the precursor particles during recovery was not affected by the presence of chloramphenicol in the recovery medium.

Bacillus subtilis↗