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Heart rate recovery after submaximal exercise testing as a predictor of mortality in a cardiovascularly healthy cohort.

BACKGROUND: Abnormal heart rate recovery after symptom-limited exercise predicts death. It is unknown whether this is also true among patients undergoing submaximal testing. OBJECTIVE: To test the prognostic implications of heart rate recovery in cardiovascularly healthy adults undergoing submaximal exercise testing. DESIGN: Population-based cohort study. SETTING: 10 primary care sites. PARTICIPANTS: 5234 adults without evidence of cardiovascular disease who were enrolled in the Lipid Research Clinics Prevalence Study. MEASUREMENTS: Heart rate recovery was defined as the change from peak heart rate to that measured 2 minutes later (heart rate recovery was defined as < or =42 beats/min). RESULTS: During 12 years of follow-up, 312 participants died. Abnormal heart rate recovery predicted death (relative risk, 2.58 [CI, 2.06 to 3.20]). After adjustment for standard risk factors, fitness, and resting and exercise heart rates, abnormal heart rate recovery remained predictive (adjusted relative risk, 1.55 [CI, 1.22 to 1.98]) (P<0.001). CONCLUSION: Even after submaximal exercise, abnormal heart rate recovery predicts death.

Adult↗

Acuity recovery and cone pigment regeneration after a bleach in patients with retinitis pigmentosa and rhodopsin mutations.

PURPOSE: To assess visual acuity recovery times and cone photopigment regeneration kinetics after a bleach in the fovea of patients with dominant retinitis pigmentosa due to rhodopsin mutations. METHODS: The authors measured acuity recovery times by computerized photostress testing in 13 patients with dominant retinitis pigmentosa and one of eight rhodopsin mutations. The authors also measured their time constants of cone photopigment regeneration with a video imaging fundus reflectometer to determine whether acuity recovery time depended on pigment regeneration kinetics. These values were compared with those of normal subjects, by the Mann-Whitney U test. The relationship between acuity recovery time and the time constant of cone photopigment regeneration among the patients was quantified by the Spearman rank correlation. RESULTS: The visual acuity recovery times, which averaged 22.0 seconds for the patients with retinitis pigmentosa and 11.2 seconds for the normal subjects, were significantly slower for the patient group (P < 0.001). The time constants of cone pigment regeneration, which averaged 172 seconds for the patients with retinitis pigmentosa and 118 seconds for the normal subjects, also were significantly slower for the patient group (P = 0.043). The authors also found a significant, positive correlation between the visual acuity recovery time and the time constant of pigment regeneration for the patients with retinitis pigmentosa (r = 0.65, P = 0.017). CONCLUSIONS: A slowing of foveal visual acuity recovery and cone pigment regeneration, which are related to each other, can occur in patients with retinitis pigmentosa, due to a rod-specific gene defect.

Adult↗

Prediction of recovery of left ventricular dysfunction after acute myocardial infarction: comparison between 99mTc-sestamibi cardiac tomography and low-dose dobutamine echocardiography.

UNLABELLED: The aim of this study was to evaluate the role of 99mTc-sestamibi cardiac imaging and dobutamine echocardiography in detecting myocardial viability early after acute myocardial infarction. METHODS: Forty-nine patients (mean age 52 +/- 10 y) underwent coronary angiography, low-dose dobutamine echocardiography, radionuclide angiography and rest 99mTc-sestamibi imaging within 10 d after myocardial infarction. Of these patients, 19 were revascularized and 30 were treated medically. Resting echocardiogram and radionuclide angiography were repeated 8 mo later to evaluate segmental functional recovery and changes in left ventricular (LV) ejection fraction, respectively. RESULTS: In revascularized patients, 61 of 108 akinetic or dyskinetic segments showed functional recovery. In these patients, sensitivity in predicting segmental functional recovery was 87% for sestamibi imaging and 66% for dobutamine echocardiography (P < 0.001), whereas specificity and accuracy were comparable. Sestamibi activity (> or =55% of peak) was the strongest predictor of segmental functional recovery (P < 0.001) and of LV ejection fraction improvement > or =5% (P < 0.01) after revascularization. In medically treated patients, 60 of 149 akinetic or dyskinetic segments showed functional recovery. In these patients, the majority (94%) of segments with contractile reserve on dobutamine were viable on sestamibi imaging and 86% of them improved function at follow-up. Functional recovery was poor in segments without contractile reserve either with (38%) or without (62%) preserved sestamibi uptake. Inotropic response was the best predictor of segmental (P < 0.001) and global (P < 0.01) LV functional improvement in medically treated patients. CONCLUSION: Dobutamine echocardiography predicts spontaneous functional recovery after acute myocardial infarction. However, sestamibi imaging is useful to identify patients with dysfunctional myocardium without contractile reserve who may benefit from coronary revascularization.

Acute Disease↗

On the reliable assessment of cardiovascular recovery: an application of curve-fitting techniques.

The underuse of cardiovascular recovery as an adjunct to reactivity may stem from a lack of research on how to assess the process reliably. We explore the test-retest reliability of three simple, intuitive approaches to measuring recovery, and of a more sophisticated curve-fitting technique. Eighteen young normotensive subjects experienced three stressors twice each, with 10-min baseline, 3-min task, and 20-min recovery periods and continuous monitoring of heart rate and blood pressure. Reactivity showed moderate reliability, but the three simple approaches to measuring recovery revealed essentially none. However, the curve-fitting approach, using a three-parameter (amount, speed, and level of recovery) logistic function was reliable. This approach, capturing the inherently dynamic process of cardiovascular recovery, may allow researchers to usefully add the assessment of recovery to paradigms exploring reactivity as a risk factor for cardiovascular disease.

Adult↗

Effect of capillary efflux transport inhibition on the determination of probe recovery during in vivo microdialysis in the brain.

Intracerebral microdialysis probe recovery (extraction fraction) may be influenced by several mass transport processes in the brain, including efflux and uptake exchange between brain and blood. Therefore, changes in probe recovery under various experimental conditions can be useful to characterize fundamental drug transport processes. Accordingly, the effect of inhibiting transport on probe recovery was investigated for two capillary efflux transporters with potentially different membrane localization and transport mechanisms, P-glycoprotein and an organic anion transporter. Fluorescein/probenecid and quinidine/LY-335979 were chosen as the substrate/inhibitor combinations for organic anion transport and P-glycoprotein-medicated transport, respectively. Probenecid decreased the probe recovery of fluorescein in frontal cortex, from 0.21 +/- 0.017 to 0.17 +/- 0.020 (p < 0.01). Quantitative microdialysis calculations indicated that probenecid treatment reduced the total brain elimination rate constant by 3-fold from 0.37 to 0.12 (ml/min. ml of extracellular fluid). In contrast, the microdialysis recovery of quinidine, delivered locally to the brain via the probe perfusate, was not sensitive to P-glycoprotein inhibition by systemically administered LY-335979, a potent and specific inhibitor of P-glycoprotein. Recovery of difluorofluorescein, an analog of fluorescein, was also decreased by probenecid in the frontal cortex but not in the ventricle cerebrospinal fluid. These experimental observations are in qualitative agreement with microdialysis theory incorporating mathematical models of transporter kinetics. These studies suggest that only in certain circumstances will efflux inhibition at the blood-brain barrier and blood-cerebrospinal fluid barrier influence the microdialysis probe recovery, and this may depend upon the substrate and inhibitor examined and their routes of administration, the localization and mechanism of the membrane transporter, as well as the microenvironment surrounding the probe.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Comparison of active and passive recovery of blood lactate and subsequent performance of repeated work bouts in ice hockey players.

This study examined the effect of active and passive recovery on lactate concentration and subsequent performance of repeated work bouts in 18 male NCAA Division I ice hockey players. Using a repeated measures design, subjects performed a series of skating tests before and after a 15-minute recovery. The skating test consisted of skating a course for 7 shifts, which lasted 40 seconds per shift with 90 seconds rest between shifts. Active recovery (low-intensity cycling) and passive recovery (sitting) lasted for 15 minutes and were followed by an identical 7-shift skating test. Passive vs. active recovery showed no statistically significant differences for distance skated, heart rate, or lactate. There appeared to be a trend for greater skating distance in period 2 when active recovery was used, but the difference was not significant (p > 0.05). It was concluded that active recovery did not enhance lactate removal or subsequent performance of repeated work bouts in simulated hockey play.

Adult↗

Reversal of mivacurium chloride: edrophonium of spontaneous recovery in microscopic laryngeal surgery.

BACKGROUND: A double-blind, randomized study was designed to compare the recovery manner of mivacurium infusion with or without edrophonium reversal in microscopic laryngeal surgery. Neuromuscular blockade was quantified using the train-of-four stimuli to the ulnar nerve and quantification of the ratio of the fourth twitch to the first twitch. METHODS: With the approval of the Human Studies Committee of the Taipei Veterans General Hospital and patient informed consent, 40 healthy (ASA I or II) patients with age from 24 to 54 years, undergoing microscopic laryngeal surgery were randomly selected for study. Mivacurium chloride 0.2 mg/kg was given intravenously, and then it was given in continuous infusion to maintain muscle relaxation at 90% twitch block during the procedure. At the end of operation, mivacurium infusion was terminated. In a double-blind manner, group I patients (n = 20) received intravenous edrophonium 1 mg/kg and atropine 0.01 mg/kg for reversal when T1 was at 10% recovery whereas patients in Group II (n = 20) received placebo in the same manner. Mean infusion rate, recovery index (RI50, time from T1 25% to T1 50%; RI75, time from T1 25% to T1 75%), extubation time, and discharge time between groups were compared. Nausea, vomiting, and dysrhythmias were also documented until the patient was discharged from hospital. RESULTS: The demographic data between two groups were similar. The recovery index (RI75) for group I was shorter than that of placebo group (5.3 +/- 2.19 min vs. 7.3 +/- 0.9 min) and the difference was statistically significant (P = 0.017). There were no statistically significant differences in mean infusion rate, incidence of nausea and vomiting, and discharge time from the POR. The incidence of tachycardia or arrhythmia in group I was significantly greater than that in group placebo. CONCLUSIONS: Mivacurium, a short-acting nondepolarizing agent, is a suitable muscle relaxant for patients receiving microscopic laryngeal surgery. Recovery time with the use of edrophonium as reversal agent was shorter than with placebo, but extubation and discharge time did not differ in two groups. The time which could be saved by the use of edrophonium for reversal of mivacurium to hasten the maximal recovery appears to be less than a few minutes. Therefore, clinically, the value of routine use of edrophonium to obtain a faster recovery does not outweigh its demerits of cost and risk and is not worthy of recommendation.

Adult↗

Recovery kinetics of oxygen uptake after cardiopulmonary exercise test and prognosis in patients with left ventricular dysfunction.

INTRODUCTION: The prognostic value of peak oxygen uptake (peak VO2) in patients with left ventricular systolic dysfunction is currently recognized and accepted. Some studies have shown that other cardiopulmonary exercise test (CPET) parameters have additional value. OBJECTIVES: To evaluate whether our population of patients with left ventricular dysfunction had similar results to those found by other investigators who showed that a slow normalization of oxygen uptake (VO2) during the recovery period of a CPET has prognostic value, and whether the recovery phase parameters have additional prognostic value to peak VO2 in these patients. METHODS: We studied 292 consecutive adult patients (81.5% male; mean age 52.4 +/- 10.6 years) with an ejection fraction below 40% (mean 23.6 +/- 8.8%) given their first symptom-limited CPET between 03/1993 and 08/2000. The etiology was ischemic heart disease in 154, idiopathic cardiomyopathy in 130 and other in 8 patients. NYHA class was I in 7%, II in 50.6% and III in 42.4% of the patients. Two years was defined as the maximum follow-up time; it was 551.5 +/- 242.2 days on average, and 62 events (death or cardiac transplantation) occurred. The following parameters were analyzed: peak VO2 (l/min and ml/kg/min), percent predicted peak VO2 (pred VO2) (l/min and ml/kg/min), VO2 every 15 seconds (sec) of the first 3 minutes of recovery (the difference between peak VO2/kg and VO2/kg every 15 sec in the recovery period (dif VO2), expressed in ml/kg/min, and also the time (sec) to reach 50% of peak VO2 (T1/2). It was considered that a combined end-point was reached if patients died or underwent cardiac transplantation. RESULTS: ROC curves of these parameters showed the following as cut-off values (area under the curve > 0.7) for the occurrence of events: peak VO2 < 60% of pred VO2, dif VO2 at 60 sec (< 3 ml/kg/min), 90 sec (< 5), 120 sec (< 8), 150 sec (< 8.6) and 180 sec (< 10.5) of the recovery and T1/2 > 115 sec. Survival analysis was performed considering pred VO2 < 60%, dif VO2 at 150 sec (the largest area under the curve) and T1/2 > 115 sec. In the survival analysis, when the decrease in VO2 at 150 sec was less than 8.6 ml/kg/min the number of patients with events increased from 9.2% to 43.5% (p < 0.001; log-rank), and when T1/2 was less than 115 sec the number of events increased from 12.3 to 34.2% (p < 0.001; log-rank). When the criteria of T1/2 and dif VO2 at 150 sec were considered together with pred VO2 < 60%, mortality increased from 31 to 54% and from 33 to 51%, respectively (p < 0.001, for both parameters; chi-square). CONCLUSIONS: A slow VO2 kinetics in the recovery period of the CPET by itself identified groups of patients with poor prognosis. The association of these parameters with peak VO2 enhanced the identification of groups at greater risk for events. A global evaluation of the CPET should be performed, considering other parameters besides peak VO2, particularly those related to VO2 kinetics in recovery (T1/2 and dif VO2 at 150 sec) as identified in this study.

Adolescent↗

Anatomical but not functional recovery from a sciatic nerve crush is enhanced by treatment with testosterone.

PURPOSE: Until recently, there has been a limited amount of research comparing functional and anatomical recovery following nerve injury. Previous studies emphasizing anatomical recovery (such as axonal number) have shown that testosterone promotes regeneration in crushed and transected nerves. The purpose of this study was to assess the effect of testosterone on the functional recovery of the sciatic nerve follow-ing a unilateral crush injury. METHODS: Young adult male Sprague-Dawley rats were injected daily with either 500 micro g testosterone proprionate or vehicle alone. The recovery course was followed for six weeks using functional and behavioral testing. Behavioral tests included a footprint gait analysis (as a measure of motor function), response to a skin pinch, and warm water withdrawal (measures of sensory function). RESULTS: Immediately following surgery, all tests indicated complete denervation to the leg distal to the crush site. Anatomical analysis revealed a 22 % increase in the number of axons in testosterone treated animals at 6 weeks post-crush, but no indication of differences in functional recovery. The results of behavioral testing indicated only minor differences in functional recovery as a result of testosterone treatment. CONCLUSION: The results indicate the need for a detailed comparison between anatomical regeneration and functional recovery. An increase in axon number alone may not be an accurate indicator of successful regeneration.

Journal Article↗

Recovery of male rats from major abdominal surgery after treatment with various analgesics.

The objective of this study was to compare the recovery of male rats after a major abdominal surgical procedure (the implantation of a radiotelemetry transmitter) when treated with buprenorphine, butorphanol, or ketoprofen and subcutaneous fluids (5% dextrose) or with subcutaneous fluids only. The parameters for assessing recovery were heart rate (HR), mean arterial blood pressure (MAP), home cage activity, food and water consumption, and body weight. HR, MAP, and activity were continuously monitored by radiotelemetry methods, food and water intakes were determined daily, and body weights were measured once or three times a week. In light of HR, nocturnal home cage activity, water consumption, and body weight gain, animals were recovered by about 7 days after surgery. MAP normalized by 1 to 2 days postsurgery, and food consumption returned to presurgical levels 5 to 12 days after surgery, depending on the analgesic treatment. On the basis of nocturnal activity, HR, and food and water intakes, buprenorphine-treated animals recovered more slowly than did the other two analgesic-treated groups. By the other parameters, all three analgesic-treated groups showed very similar responses across time. Surprisingly, when compared with the groups receiving only subcutaneous fluids, buprenorphine and butorphanol delayed or did not advance recovery, whereas ketoprofen neither retarded nor advanced recovery. Explanations for these results include: (a) the analgesics were effective in relieving pain but had pharmacological side effects that altered the measured parameters, making it difficult to determine recovery; (b) the level of pain experienced did not notably affect recovery; (c) the analgesics, at the doses and/or dosing schedules used, were not effective in the relief of pain, thereby causing both groups of animals to recover at the same rate; and (d) the analgesics interfered with recovery. Final resolution of these issues awaits further investigation.

Abdomen↗

[Refractory recovery function of electrical auditory on the survival auditory nerve in cochlear implant recipients].

OBJECTIVE: To evaluate the cochlear implant recipient's electrical auditory temporal properties in order to estimate the maximum stimulating rate which can be reached when they adopted some speech coding strategies based on time mechanism, such as continuous interleaved sampling (CIS). METHODS: Thirty-eight Nucleus CI24 cochlear implant recipients were divided into 4 groups by etiology and history. Their survival auditory nerve fibers' refractory recovery time function was measured via neural response telemetry (NRT). Electrical pulses with the amplitude of recipient's loudest acceptable presentation were stimulated in mono-polar mode, with the width of 25 microseconds and the frequency of 80 Hz. Least-squares regression procedures were used to fit individual recovery functions with the equation A = C + K e(-t/tau), in which tau is the time constant of recovery from refractory state. Statistic analysis showed the relationship between the time constants of individuals and etiology as well as electrode position in the cochlea. RESULTS: Congenital deaf patient's recovery time constants were shorter than that of postnatal deaf groups of ototoxicity (P = 0.0056) and large vestibular aqueduct syndrome (P = 0.0349). There was no significant difference between the recovery time constants of congenital deaf patients and those of group with long history of deafness. The ANOVA of the recovery time constants of 5th, 10th, 15th electrode showed no significant statistical difference (P > 0.05). CONCLUSION: The recovery time constants are related with etiology. In mono-polar mode, the time constants of congenital deafness or subjects with short duration of deafness are shorter than those of postnatal deafness or subjects with long duration of deafness. Time constants do not vary systematically with electrode location along the implanted array. The reciprocal of individual electrode seems to be used in determining the maximum of stimulating rate of CIS strategy and as criteria of choosing the usable channels from 22 electrode bands.

Acoustic Stimulation↗

Promoting neurological recovery following a traumatic peripheral nerve injury.

If a peripheral nerve is crushed, or if the nerve is cut and the ends sutured together soon after the lesion (anastomosed), neurological recovery is good. When a length of a peripheral nerve is destroyed, and anastomosis is not possible, the standard surgical repair technique is to graft a length/s of sensory nerve from the patient, into the gap. For gaps <2 cm neurological recovery is moderate, for gaps 2-4 cm recovery is generally poor, and for gaps >4 cm recovery is limited to non-existent. The limited recovery is because sensory nerves act as passive scaffolds for axon regeneration and do not actively promote axon regeneration. However, such grafts remain the "gold standard" for nerve repairs. New techniques are required that induce improved neurological recovery. This paper reviews current clinical and basic research techniques for inducing neurological recovery following traumatic peripheral nerve injuries.

Humans↗

Blood lactate removal during recovery at various intensities below the individual anaerobic threshold in triathletes.

AIM: Optimal lactate removal was reported to occur at work-rate between 30% and 70% VO2max. However, it has been recently recommended to quantify exercise intensity not in percentage of VO2max but in relation to validated metabolic reference points such as the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT). The purpose of this study was to examine the effect on lactate removal of different recovery work-rates below the IAT defined calculating the difference (DT) between IAT and IVT, then choosing the IVT+50%DT, the IVT and the IVT-50%DT work-rates. METHODS: Eight male triathletes (VO2max 69.7+/-4.7, VO2IAT 52.9+/-4, VO2IVT 41.1+/-4.7 mL x kg(-1) x min(-1)), after a 6-min treadmill run at 75% of difference between IAT and VO2max, performed in a random order the following 30-min recovery treatments: 1) run at IVT(plus;50%DT), 2) at IVT, 3) at IVT(-50%DT), 4) passive. Blood lactate was measured at 1, 3, 6, 9, 12, 15, 20, 25, 30 minutes of recovery. RESULTS: All active recovery work-rates (from 50+/-5% to 67+/-4% VO2max) were within the range previously reported for optimal lactate removal, and significantly more efficient than passive recovery on lactate removal curve (% of accumulated lactate above rest value). However, significant differences (P<0.01) were found among active recovery intensities: the IVT(-50%DT) was the most efficient work-rate from the 9th minute to 30th minute. CONCLUSIONS: In triathletes, the IVT(-50%DT) was the optimal work-rate for lactate removal; moreover none of the studied active work-rate showed further lactate decrease after the 20th minute of recovery.

Acid-Base Equilibrium↗

Cytomegalovirus infection causes delayed platelet recovery after bone marrow transplantation.

The pathogenic effect of cytomegalovirus (CMV) infection on the hematopoietic recovery after bone marrow transplantation (BMT) was retrospectively studied in 87 recipients of (nonpurged) autologous BMT and in 56 recipients of allogeneic BMT from HLA-identical siblings. Indications for autologous BMT were lymphomas or acute leukemias and for allogeneic BMT various malignancies or aplastic anemia. Patients were divided for the study in two groups, CMV-positive and CMV-negative on the basis of the CMV status pretransplant, and CMV-negative patients were kept CMV-negative by the local transfusion policy. In allogeneic BMT recipients, platelet recovery was significantly slower in CMV-positive patients than in CMV-negative patients (platelets greater than 50,000 cells/microL after 41 days v 27 days, P = .007). This difference held true when patients with acute graft-versus-host disease above grade I were excluded (platelets greater than 50,000 cells/microL after 42 days v 24 days, P = .01). In autologous BMT, the negative effect on platelet recovery was present in patients with lymphomas, but absent in patients with acute leukemias. Patients with acute leukemias had a very delayed recovery of platelets and granulocytes after autologous BMT, irrespective of the CMV status, probably due to the original stem cell disorder. Platelet recovery was significantly slower in CMV-positive autologous BMT recipients with lymphomas than in those not infected (platelets greater than 50,000 cells/microL after 36 days v 24 days, P = .0002). The presence of CMV infection had no effect on the recovery of granulocytes in autologous or allogeneic BMT. These data show that CMV infection causes delayed platelet recovery after BMT; however, in autologous BMT, the underlying disease (ie, acute leukemia) is more determinant for hematopoiesis after BMT.

Adult↗

Effect of a specialized pediatric institutional setting on organ recovery from potential donors.

BACKGROUND: The relationship between accessibility to the full range of subspecialty care available at freestanding pediatric hospitals and organ donor management and recovery rates has not been studied. OBJECTIVE: To examine current rates of recovery of organs from children for transplantation at free-standing pediatric hospitals versus all other hospitals. METHODS: Data from the hospitals served by Mid-America Transplant Services from January 2000 to July 2003 were reviewed. Organ recovery rates from freestanding children's hospitals were compared with the rates from other types of institutions. Patients were included if their organs were considered medically suitable at the time of referral for donation. RESULTS: Overall, 66% (210/318) of the potential organs were recovered. The type of institution in which the potential donor was managed did not influence the proportion of organs recovered: 67% (96/144) at freestanding children's hospitals versus 66% (114/174) at all other hospitals. A greater proportion of livers were recovered at other donor institutions than at children's hospitals (100% vs 85%, P< or =.01). CONCLUSION: The organ recovery rate from potential pediatric donors is low. In general, this rate does not appear to be affected by the type of managing pediatric institution except for liver recovery, which favors institutions that are not freestanding children's hospitals. The low rate of recovery suggests that although suitable donors are identified, appropriate referrals are made, and families provide consent for donation, major obstacles remain to the successful recovery of organs.

Adolescent↗

Immature platelet fraction as a predictor of platelet recovery following hematopoietic progenitor cell transplantation.

The immature platelet fraction (IPF) as determined by the Sysmex XE-2100 is a rapid automated measure of the least mature component of the platelet population and is thought to correlate with thrombopoietic activity of the marrow. We investigated the ability of IPF to predict platelet recovery following hematopoietic progenitor cell (HPC) transplantation. IPF was compared to standard parameters of hematopoietic recovery, including the immature reticulocyte fraction (IRF), an early predictor of recovery. Fifty patients undergoing peripheral blood HPC transplantation (38 autologous and 12 allogeneic) were followed daily for 11 to 28 days after transplantation with measurement of IPF, IRF, absolute neutrophil counts (ANC) and platelet counts. Mean days to recovery for IPF was 3.1 days less than for platelet count (P <.0001), 3.8 days less than for ANC (P <.0001), and 0.6 days less than for IRF (P = .0477). IPF recovered at least 1 day prior to platelet count in 79% (38 of 48) of patients, and was followed by platelet count recovery within 1 to 12 days (mean, 4.1 days). When autologous and allogeneic patient groups were analyzed separately, IPF recovered significantly earlier than platelet count and ANC in both groups (P <.0001). Thrombopoietin (TPO) levels in 5 patients receiving transplants correlated with IPF; however, this appeared to be secondary to an inverse correlation of both TPO and IPF with platelet count. IPF is comparable to IRF as one of the earliest predictors of hematopoietic recovery following peripheral blood HPC transplantation. IPF could potentially be useful as a predictor of platelet recovery in other bone marrow failure syndromes.

Adolescent↗

Inhibitors of repair of potentially lethal damage and DNA polymerases also influence the recovery of potentially neoplastic transforming damage in C3H10T-1/2 cells.

The effects of aphidicolin and beta Ara A on radiation sensitivity were evaluated in terms of cell killing, recovery, and neoplastic transformation in the C3H10T-1/2 cell system. When cells were held in plateau phase, recovery of potentially lethal damage (PLD) and potentially transforming damage (PTD) occurred. The addition of beta Ara A resulted in reduced PLD recovery for both the survival and neoplastic transformation end points. The addition of aphidicolin did not affect recovery of PLD or PTD. These data show that the inhibition of polymerase alpha by aphidicolin does not affect recovery of damage leading to cell death or neoplastic transformation. However, the inhibition of both polymerase alpha and beta by beta Ara A resulted in inhibition of recovery of damage leading to both cell death and neoplastic transformation. These data indicated that polymerase beta may be involved in both PLD and PTD recovery.

Animals↗

Incision depth affects the recovery of corneal sensitivity and neural regeneration in the cat.

To assess the effect of incision depth on the recovery of corneal sensitivity and neural regeneration, adult domestic cats underwent either 8-mm circular nonpenetrating keratotomies or penetrating autografts. The contralateral eye served as control. Corneal sensitivity was determined at various intervals after surgery. The depth of incision in the nonpenetrating keratotomies, assessed by optical pachometry, ranged between 49 and 91% of total corneal thickness. The animals were ranked based on the depth of incision and the average sensitivity within the keratotomy over the 1-yr recovery period. A significant negative correlation was found between incision depth and the recovery of sensitivity (Spearman rank-order correlation r = -0.84, P less than 0.05). Some recovery of sensitivity was found in the center and periphery of the incised zone when incision depth was less than 53% of total corneal thickness. With deeper incisions, the center of the incised zone remained insensitive throughout the measurement period, while the periphery of the incised zone showed a slight recovery of corneal sensitivity, proportional to incision depth. The recovery of corneal sensitivity was higher in a small annular region just distal to the incision site. When incision depth exceeded approximately 53%, gold chloride impregnation showed that the resultant reinnervation was confined to single intraepithelial axons or localized regions of irregular epithelial fibers. With shallower incisions, the deeper stromal trunks were spared, resulting in the persistence of a reduced subepithelial plexus and basal epithelial leashes. We have shown that when an incision severs all stromal trunks, the neural regeneration is insufficient for functional recovery of corneal sensitivity at the center of an 8-mm keratotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗