[A study of the nature of the resting potential of Nitella cells. 2. The effect of the pH of the medium on the resting potential of Nitella cells].
Explore the source record for details and available documents.
Hydrogen-Ion Concentration↗
SEARCH · Search PubMed
Results for “REST”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Tennis elbow--to rest or not to rest?
Explore the source record for details and available documents.
Adult↗
[Clinical study on the resting state of accommodation. Report 2. The resting state of accommodation on the refraction-abnormal eyes (author's transl)].
Explore the source record for details and available documents.
Accommodation, Ocular↗
Diminished post-rest potentiation of contractile force in human dilated cardiomyopathy. Functional evidence for alterations in intracellular Ca2+ handling.
Post-rest contractile behavior of isolated myocardium indicates the capacity of the sarcoplasmic reticulum (SR) to store and release Ca2+. We investigated post-rest behavior in isolated muscle strips from nonfailing (NF) and endstage failing (dilated cardiomyopathy [DCM]) human hearts. At a basal stimulation frequency of 1 Hz, contractile parameters of the first twitch after increasing rest intervals (2-240 s) were evaluated. In NF (n = 9), steady state twitch tension was 13.7 +/- 1.8 mN/mm2. With increasing rest intervals, post-rest twitch tension continuously increased to maximally 29.9 +/- 4.1 mN/mm2 after 120s (P < 0.05) and to 26.7 +/- 4.5 mN after 240 s rest. In DCM (n = 22), basal twitch tension was 10.0 +/- 1.5 mN/mm2 and increased to maximally 13.6 +/- 2.2 mN/mm2 after 20 s rest (P < 0.05). With longer rest intervals, however, post-rest twitch tension continuously declined (rest decay) to 4.7 +/- 1.0 mN/mm2 at 240 s (P < 0.05). The rest-dependent changes in twitch tension were associated with parallel changes in intracellular Ca2- transients in NF and DCM (aequorin method). The relation between rest-induced changes in twitch tension and aequorin light emission was similar in NF and DCM, indicating preserved Ca(2-)-responsiveness of the myofilaments. Ryanodine (1 microM) completely abolished post-rest potentiation. Increasing basal stimulation frequency (2 Hz) augmented post-rest potentiation, but did not prevent rest decay after longer rest intervals in DCM. The altered post-rest behavior in failing human myocardium indicates disturbed intracellular Ca2- handling involving altered function of the SR.
Adult↗
Reliability of resting heart rate measurements in atrial fibrillation.
BACKGROUND: Heart rate (HR) control in atrial fibrillation (AF) is commonly guided by resting HR measurements, usually with 12‑lead ECG or in-office pulse palpation. OBJECTIVES: We aimed to assess the reliability of resting HR measurements in AF patients with long-term ambulatory ECG and activity monitoring. METHODS: We included patients who had recorded a full-disclosure ambulatory ECG with a mobile cardiac telemetry device equipped with an accelerometer (PocketECG, MEDICALgorithmics, Poland), with at least 95% AF. Resting HR samples (≤20 per individual/day) were collected as 10-s daytime (8 am to 8 pm) measurements after ≥10 min of rest. These samples were compared to each individual's mean daytime resting HR. RESULTS: In 832 patients (median age 77 (interquartile range (IQR) 69-83) years, 42% women) with a median registration duration of 13 days (IQR 7-22), the population mean daytime resting HR was 85 (±15) beats per minute (bpm). A single resting HR differed from the mean daytime resting HR by a mean of ±10.4% (IQR 3.6-14.4%). When the mean daytime resting HR was ≥110 bpm, 29% of resting HR samples were < 110 bpm, and when the mean daytime resting HR was 80-109 bpm,11% of samples were ≥ 110 bpm. Resting HR measurement variability decreased to 5.3% (IQR 1.9-7.5%) when four resting HR samples were averaged. CONCLUSION: In patients with AF, a single resting HR measurement often differs substantially from the mean daytime resting HR. When a precise measurement is clinically relevant, repeated resting HR sampling or ambulatory monitoring can address this measurement imprecision.
Humans↗
[Relationships between resting behavior and health locus of control among elementary schoolgirls].
PURPOSE: To clarify the effects of Internal Health Locus of Control (IHLC) on the practice of resting behavior. Resting has recently gained attention because of overwork and stressful social situations. We investigated daily preventive health behaviors and Health Locus of Control (HLC) in children and their mothers over three years from 1991. This paper reports on the relationships between resting and IHLC among elementary schoolgirls. METHODS: The subjects of this study in 1991 were public elementary schoolgirls in their 3rd year (8-9 years old) and their mothers. Three years, later in 1994, we investigated the same children and their mothers, with 104 girls answering questionnaires in both studies. The resting behavior data was obtained from the question "Do you rest or take a nap when you are very tired?". We used Parcel & Meyer's Children's HLC Scales for children and Horige's Japanese version of Health Locus of Control (JHLC) Scales for mothers. Only the data concerning IHLC was extrapolated for this study. RESULTS: 1. The data for resting behavior for 1991 in the 3rd grade did not coincide with that for 1994 in the 6th grade. On the whole rest was taken more frequently in the 3rd grade than in the 6th grade. 2. Perceived health state had a significant association with resting behavior. 3. Girls who perceived rest was relating directly to their personal health, took a rest more often than those who did not perceive a personal application for rest. 4. IHLC data distribution shows a marked difference between grades. Scores were significantly higher in the 6th grade than in the 3rd grade. This rising tendency of internality seems to be a developmental change. 5. IHLC scores of 1991 3rd graders classified their 3rd grade behavior patterns. The 3rd grade (1991) "usually taking a rest" group scored significantly higher than the other groups. 1991 IHLC scores classified their 1994 6th grade behavior patterns. The 6th grade (1994) "usually taking a rest" group also scored significantly higher than the other groups. 6. The data for resting behavior of the girls did not coincide with that of their mothers. There were no correlations between the girls's IHLC scores and their mothers's IHLC scores. CONCLUSION: This study revealed some significant relationships between resting behaviors and IHLC scores among the schoolgirls. It seems that girls who had high IHLC tendency in the 3rd grade were growing up with this tendency. Perhaps in the interest of self-care, they elected to rest to keep healthy when they were tired.
Adult↗
The routine use of sublingual GTN with resting 99Tcm-tetrofosmin myocardial perfusion imaging.
Nitrates can be used to improve resting myocardial blood flow in patients with severe coronary artery disease. This may enhance tracer uptake during rest myocardial perfusion imaging. Recent studies using nitrates at rest have shown increased detection of reversible ischaemia in this patient group with the 201Tl and 99Tcm perfusion tracers MIBI and tetrofosmin. However, it is not always possible to assess the severity of coronary artery disease before the rest injection and therefore whether a patient would benefit from nitrate administration. To improve the sensitivity for the detection of reversible ischaemia and to avoid a repeat study with nitrates (especially in patients with 'fixed' defects), a protocol in which all patients routinely receive nitrates prior to the rest injection is required. This prospective study evaluated the effect of nitrate administration prior to rest imaging in a randomly selected group of patients. Thirty patients selected at random from routine referrals had stress, rest and rest + GTN tetrofosmin imaging on three separate days. Changes in reversibility between the rest and rest + GTN images were assessed both visually and using semi-quantitative analysis. Defects at stress were seen in 43 coronary artery territories, 33 of which were reversible at rest and 37 reversible at rest + GTN. Of these 43 defects, 82% demonstrated either increased or the same degree of reversibility at rest + GTN imaging compared to standard rest imaging. All defects with reduced reversibility at rest + GTN imaging (i.e. the remaining 18%) were, however, still reversible compared to the stress images. Some of this reduced reversibility may be due to attenuation artefacts. We conclude that the routine use of GTN with rest tetrofosmin imaging will result in increased detection of ischaemic areas with no loss of sensitivity or specificity.
Administration, Sublingual↗
Incremental prognostic value of rest-redistribution (201)Tl single-photon emission computed tomography.
BACKGROUND: The incremental prognostic value of rest-redistribution (201)Tl compared with stress and rest perfusion abnormalities has not been defined. METHODS AND RESULTS: We identified 458 patients who underwent rest (201)Tl /stress (exercise or adenosine) (99m)Tc sestamibi single-photon emission computed tomography (SPECT) and had late (18 to 24 hours) (201)Tl imaging, were not revascularized within 60 days of SPECT, and were followed up at >1 year. SPECT images were visually analyzed with the use of a 20-segment model on a scale of 0 to 4. Thirty-seven cardiac deaths (CDs) and 17 nonfatal myocardial infarctions occurred. Univariate Cox proportional hazards analysis showed that the presence of a large amount of rest (201)Tl reversibility (rest-late summed difference score [SDS] of >8) was a significant predictor of CD (chi(2) = 5.77, P = 0.02) and CD or myocardial infarction (chi(2) = 5.3, P = 0.02). The CD rate was 9.3% y(-1) in patients with rest-late SDS of >8 compared with 3.6% y(-1) in patients with a mild/moderate amount of rest reversibility (rest-late SDS 3 to 8) and 3.4% y(-1) in patients with no rest reversibility (rest-late SDS <3) (P = 0.029). Kaplan-Meier survival analysis demonstrated significantly lower cumulative survival rates in patients with rest-late SDS of >8 (P = 0.01). Multivariate Cox proportional hazards analysis demonstrated that the presence of a large amount of resting reversibility was an independent and incremental predictor of CD after adjustment for stress and rest perfusion information. Multivariate logistic regression analysis demonstrated that resting reversibility was not an independent predictor of referral to coronary angiography and revascularization. CONCLUSIONS: The identification of a large amount of resting (201)Tl reversibility is an independent predictor of CD over stress and rest perfusion abnormalities.
Aged↗
Biochemical and hormonal changes in endurance trained volunteers during and after exposure to bed rest and chronic hyperhydration.
The objective of this investigation was to assess the effect of a daily intake of fluid and salt supplementation on biochemical and hormonal changes in endurance trained volunteers aged 19-24 yrs during 30-day bed rest and during 15 days of post bed rest period. The studies were performed on 30 long distance runners aged 19-24 yrs who had a peak oxygen uptake of 66 ml/kg/min and had taken 14.5 km/day on average prior to their participation in the study. The volunteers were divided into three groups: the volunteers in the first group were under normal ambulatory conditions (control subjects); the second group subjected to bed rest alone unsupplemented (bed rested volunteers); the third group was submitted to bed rest and consumed daily 30 ml water/kg bodyweight and 0.1 g of sodium chloride (NaCl)/kg body weight (supplemented bed rested volunteers). The second and third groups of volunteers were kept under a rigorous bed rest regime for 30 days. During the pre bed rest period of 15 days, during the bed rest period of 30 days and during the post bed rest period of 15 days cyclic adenosine monophosphate, cyclic guanosine monophosphate, prostaglandins of pressor, prostaglandins depressor groups, renin activity in plasma and aldosterone in plasma and in urine were determined. We found that in bed rested volunteers without fluid and salt supplementation intake plasma renin activity and aldosterone in plasma and urine continued to increase during the bed rest period as plasma volume decreased. Moreover, in this group, cyclic nucleotides measured as an indicator of adrenosympathetic system activity increased and prostaglandins as local vasoactive substances decreased during the bed rest period. These variables returned toward the baselines in the post bed rest period as plasma volume deficit was restituted. On the other hand, the hormonal levels in the other two groups remained rather constant during the experimental period. We concluded that daily intake of fluid and salt supplementation may minimize the biochemical and hormonal changes in endurance trained volunteers dorm their exposure to bed rest conditions.
Adult↗
Effects of relaxation associated with brief restricted environmental stimulation therapy (REST) on plasma cortisol, ACTH, and LH.
Restricted Environmental Stimulation Therapy (REST), which involves placing an individual into an environment of severely reduced stimulation for brief periods, has been subjectively reported to produce deep relaxation. The present study determines the effects of REST-assisted relaxation on plasma cortisol, ACTH, and luteinizing hormone (LH). These parameters were also measured in a group exposed to a similar relaxation paradigm, but without REST (non-REST). Each subject experienced two baseline sessions (1 and 2), four REST (or non-REST) relaxation sessions (3, 4, 5, 6), and two follow-up sessions (7 and 8). Pre- and postsession plasma hormone levels were measured in sessions 1, 2, 5, and 8. Both REST and non-REST subjects reported that the experience was relaxing. During the treatment period (session 5) pre- to postsession changes in cortisol and ACTH, but not in LH, were significantly greater for the REST group than for the non-REST group. Plasma cortisol level also decreased across sessions in the REST group, with levels in sessions 5 and 8 significantly lower than the baseline (sessions 1 and 2). Non-Rest subjects showed no change in plasma cortisol across sessions. No significant change in plasma ACTH or LH occurred across sessions in the REST or non-REST groups, although ACTH showed a decreasing trend. These data demonstrate that repeated brief REST-assisted relaxation produces a relaxation state associated with specific decreases in pituitary-adrenal axis activity.
Adrenocorticotropic Hormone↗
Effects of caffeine and ryanodine on depression of post-rest tension development produced by Bay K 8644 in canine ventricular muscle.
1. Post-rest inotropy in canine ventricular myocardium has proved a useful indicator of sarcoplasmic reticular calcium release. This phenomenon is converted to rest depression by the calcium channel activator (agonist), Bay K 8644 as well as other chemically diverse agents such as caffeine and ryanodine. 2. Rapid cooling contractures and post-rest contraction amplitude were used as independent measures of sarcoplasmic reticular calcium content and release. Simultaneous recordings of transmembrane action potentials and their accompanying contractions were obtained to determine the association between electrophysiological and mechanical events. The present study was designed to elucidate the mechanism by which Bay K 8644, caffeine and ryanodine alter force production after variable periods of rest. 3. Bay K 8644 (1 microM) increased steady state contraction in response to a constant train of stimulation, caused rest-depression after 2 and 8 min rest, prolonged action potential duration and increased action potential plateau amplitude. Augmented steady state tension was not accompanied by any change in time to peak tension or rapid cooling contracture amplitude. However, the post-rest rapid cooling contracture was greatly diminished compared to that observed prior to Bay K 8644 treatment. 4. Caffeine (3 and 5 mM) caused rest-depression with an increase in steady state contraction amplitude. Along with this there was a slight decrease in action potential duration and plateau amplitude and an increase in time to peak tension. The rapid cooling contractures were virtually abolished at all conditioning intervals. The effect of caffeine on twitch tension and cooling contracture is consistent with the ability of this compound to inhibit calcium sequestration by the sarcoplasmic reticulum. 5. A combination of Bay K 8644 and caffeine caused significantly less rest-depression than that seen with Bay K 8644 alone. The augmented twitch tension was accompanied by a long time to peak tension and action potential duration. However, there was no increase in the amplitude of the rapid cooling contracture, either after a regular train of stimulation or after rest, compared to that seen after Bay K 8644. 6. Ryanodine (10 nM), produced rest-depression, reduced steady state twitch tension and augmented the rest-depression produced by Bay K 8644. The steady state rapid cooling contracture remained unchanged when both agents were present simultaneously, while the post-rest rapid cooling contracture was significantly depressed compared to that observed with Bay K 8644 alone. 7. Bay K 8644 and ryanodine appear to have similar actions with respect to promoting diastolic loss of calcium from the sarcoplasmic reticulum. Although caffeine also decreases post-rest potentiation, it antagonizes rest-depression caused by Bay K 8644. The data from these experiments suggest that this reversal is a result of depressed intracellular calcium buffering and enhanced myofilament sensitivity produced by caffeine in the presence of increased transmembrane calcium influx promoted by Bay K 8644.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
Assessment for rest home subsidy: are the elderly getting a fair deal?
AIM: To describe the role of a geriatric service in assessing the needs of elderly people at home or in rest homes referred for a subsidy for rest home care, and to compare this assessment with the composite dependency scale (CDS), a Department of Social Welfare assessment instrument. METHODS: A 47 item questionnaire was completed by the geriatric service at the time of assessment of elderly people in the community or in rest homes. RESULTS: Of 280 assessments, 100 were from private homes, 180 from rest homes. Sixty-three per cent in rest homes were referred only because private funds were exhausted, 33% for a change in dependency category. These two groups plus those at home were used as a basis for comparison in subsequent analysis. Of those at home: 30% already had a rest home bed arranged; 77% remembered being consulted about rest home care, but only 38% were sure they wanted to go into such care. The proportion of those too independent or too sick for rest home care was: private homes 14%, rest home resident requiring subsidy 6%, rest home requiring change in category status 11%. Twenty three percent of those at home could continue there with or without additional support. No significant difference was found in dependency between those in rest homes only seeking funding, and those at home, but both of these groups were significantly less dependent than those seeking an increase in subsidy. There was only a moderate correlation (rs = 0.778) between the geriatric service assessment of dependency and the composite dependency score. CONCLUSIONS: Many elderly people do not feel properly consulted about rest home placement, and some could be supported at home for longer. It is likely that many who can afford rest home fees are entering too early and then asking for a subsidy when their funds are exhausted. By then it is almost impossible to insist on alternatives in the community. A policy of geriatric service assessment for all seeking entry into rest home care should ensure independent consultation and consideration of alternative strategies. More research is required to examine cost implications of unrestricted movement into rest homes.
Aged↗
Urinary and plasma calcium changes in endurance trained volunteers during exposure to acute and rigorous bed rest conditions.
The purpose of the present study was to evaluate the effect of acute (abrupt restriction of muscular activity) and rigorous bed-rest conditions on urinary and plasma calcium changes in endurance trained volunteers. The studies were performed on 30 long distance runners ages 23-25 who had a peak oxygen uptake of 66.0 mL/min/kg and had run 14.0 km/d on the average prior to their participation in the study. The volunteers were divided into three groups: The volunteers in the first group were under normal ambulatory conditions (control subjects), the second group was subjected to an acute bed-rest regime (acute bed-rested subjects), and the third group was submitted to a rigorous bed-rest regime (rigorous bed-rested subjects). The second and third groups of volunteers were kept under a rigorous bed rest regime for 7 d. During the pre-bed-rest period and during the actual bed-rest periods (acute and rigorous bed-rest periods), urinary excretion of calcium and plasma calcium and parathyroid hormone (PTH) concentrations were determined. During the 1st d of acute and rigorous bed-rest periods, urinary excretion and plasma concentration of calcium increased significantly (P < or = 0.05), while plasma parathyroid hormone content decreased significantly (P < or = 0.05). On the 3rd d of the experimental period, urinary excretion and plasma calcium concentration decreased somewhat, during the 7th d, calcium in urine and plasma increased further, while parathyroid hormone content in plasma increased somewhat on the 3rd d and decreased again on the 7th d of the experimental period. The changes were more pronounced in the volunteers who were subjected to acute bed-rest conditions than in the volunteers who were submitted to rigorous bed-rest conditions. It was concluded that exposure to acute bed-rest conditions induces significantly greater urinary and serum calcium changes than rigorous bed-rest conditions in endurance trained volunteers.
Bed Rest↗
Functional interconversion of rest decay and ryanodine effects in rabbit and rat ventricle depends on Na/Ca exchange.
Rapid cooling contractures were used to assess changes in sarcoplasmic reticulum (SR) Ca content in isolated rabbit and rat ventricular muscle during rest, with altered transsarcolemmal [Na] and [Ca] gradients and in the presence and absence of 100 nM ryanodine. In rabbit there is normally a rest-duration dependent decline in SR Ca content (rest decay), whereas in rat there is a short-term increase in SR Ca content (rest potentiation) and little evidence of rest decay. Ryanodine greatly accelerates the rate of rest decay in rabbit, depleting the SR of Ca in approximately 1 s, whereas in rat, ryanodine does not appear to drain the SR even after a 10 min rest. Elevation of intracellular Na activity in rabbit (by Na-pump inhibition) to a level similar to that measured in control rat during rest (Shattock and Bers, Am. F. Physiol., 256: C813-C822, 1989) makes rest-dependent changes of SR Ca content in these two tissues similar. The rest decay in rabbit in the presence of ryanodine is also markedly slowed after Na-pump inhibition. In rat, reduction of [Ca]0 allows rest decay to occur (+/- ryanodine), but this rest decay can be largely prevented by simultaneous reduction of [Na]o (to maintain [Na]3/[ Ca] constant) which serves to keep the thermodynamic driving force on a 3:1 Na/Ca exchange constant. We conclude that the process of rest decay and rest potentiation in both rabbit and rat ventricle depends on the sarcolemmal Na/Ca exchange. Furthermore, these species can be functionally interconverted by manipulation of the [Na] and [Ca] gradients. The ability of ryanodine to deplete the SR of Ca also depends critically on other transport systems (particularly Na/Ca exchange) to remove Ca from the cytoplasm.
Animals↗
Should ileoanal pouch surgery be denied to patients with low resting pressures?
Our aim was to evaluate any impact of preoperative resting pressure upon postoperative physiological results in patients undergoing ileal pouch anal anastomosis. Ninety patients who had undergone manometric study before and 1 year after surgery were divided into two groups determined by a preoperative mean resting pressure of > 50 mm Hg or < or = 50 mm Hg. There were significant differences between these two groups concerning preoperative maximum resting pressure (P < 0.001) and length of the high-pressure zone (P < 0.005). However, such a trend was not seen postoperatively. There were no differences between these two groups relative to postoperative mean or maximum resting pressure, maximum squeeze pressure, length of high-pressure zone, sensory threshold, or capacity. The mean resting pressure decreased after pouch surgery in 82 per cent of patients with a preoperative mean resting pressure of > 50 mm Hg. Conversely, 83 per cent of patients with a preoperative mean resting pressure of < or = 50 mm Hg experienced an increase in mean resting pressure after pouch surgery. Only 4 of 23 patients with a preoperative mean resting pressure of < or = 50 mm Hg had decreased postoperative mean resting pressure. This latter finding has not been previously described. However, the mean resting pressure of those four patients more than fully recovered within 2 to 3 years after surgery. Although preoperative manometry may be useful to analyze data and to counsel patients, it should not be used to deny patients surgery. Moreover, this study has revealed that patients with lower resting pressures do not suffer a deleterious decrease in resting pressure but actually have improved postoperative mean resting pressure.
Adenomatous Polyposis Coli↗
Resting metabolic rate in subjects with paraplegia: the effect of pressure sores.
OBJECTIVE: To determine the overall effect of paraplegia and pressure sores on resting metabolic rate. DESIGN: Unblinded, case-control study using a convenience sample. SETTING: Hospital primary care setting. PATIENTS: Fourteen individuals with paraplegia and pressure sores (PS-Para), 24 with paraplegia in good health (NPS-Para), and 23 non-spinal cord injury (SCI) controls. MAIN OUTCOME MEASURES: The planned outcome measures consisted of resting metabolic rate, percent of predicted resting metabolic rate, resting metabolic rate per kilogram body weight, and resting metabolic rate per meter squared body surface area. Post hoc analyses were used to identify the effect of completeness of lesion, smoking, and pressure sores on percent of predicted resting metabolic rate and resting metabolic rate per kilogram body weight. RESULTS: Percent of predicted resting metabolic rate and resting metabolic rate per kilogram body weight were significantly higher in the PS-Para group than in the NPS-Para or control groups (115% +/- 4% vs 100% +/- 2% or 107% +/- 2%, p < .05) and (25.9 +/- 1.2 vs 21.4 +/- 0.6 or 22.5 +/- 0.4 kcal/kg, p < .05, respectively). The resting metabolic rate per meter squared body surface area was significantly higher in the PS-Para group than in NPS-Para group (973 +/- 39 vs 874 +/- 20kcal/m2, p < .05). In the PS-Para group, current smokers had significantly higher resting metabolic rate per kilogram body weight than nonsmokers (27.3 +/- 1.7 vs 24.0 +/- 1.4kcal/kg, p < .01). Controlling for the effects of smoking in a multiple regression model, those in the PS-Para group had significantly (p < .001) greater percent of predicted resting metabolic rate and resting metabolic rate per kilogram body weight than those in the NPS-Para group. CONCLUSIONS: These findings indicate that individuals with SCI may have a decreased percent of predicted resting metabolic rate and those with pressure sores may have a hypermetabolic state. This hypermetabolic state is significantly higher than that resulting from smoking. Because ordinary prediction equations for energy expenditure may not be accurate when applied to subjects with paraplegia and pressure sores, quantification of energy needs by indirect calorimetry is recommended.
Basal Metabolism↗
A new approach for rapid assessment of the cardiac rest period for coronary MRA.
BACKGROUND: Effective suppression of cardiac motion is crucial for MR coronary angiography (MRCA). Thus, we evaluated a new technique for rapid and automatic detection of the cardiac rest period in comparison to the conventional visual assessment of the coronary artery rest periods. METHODS: One hundred and thirty-five consecutive cardiac patients were examined (Philips Intera CV 1.5 T, Best, The Netherlands). Visual assessment of the left and right coronary rest periods was done using a cine-SSFP scan with a transversal slice orientation (retrospective gating, 40 phases/cardiac cycle); the coronary rest period was defined as the duration of the coronary artery being completely within a region of interest placed on the outer edge of the cross-section of the vessel. Common coronary rest period as determined from visual assessment was defined as the intersection of both coronary artery rest periods. For comparison, an automatic technique was applied: using the position of the shim volume to define a correlation kernel, the cross-correlations of consecutive cine images were registered and displayed in a graph. Based on these cross-correlation values, the cardiac rest period was detected. The correlation between the visual and automated analysis was assessed. RESULTS: A high correlation between the automatically and visually determined starting points for the coronary artery rest periods and the cardiac rest period was found. The automatically assessed cardiac rest period was significantly shorter in comparison to the visually assessed left and right coronary artery rest period (103 +/- 46 ms vs. 158 +/- 72 ms and 117 +/- 52 ms, respectively; p < 0.001). However, the common coronary rest period demonstrated excellent agreement with the cardiac rest period (r = 0.93, p < 0.001) without a significant difference in duration (109 +/- 52 ms vs. 103 +/- 46 ms). CONCLUSIONS: Automated analysis of the cardiac rest period yielded similar results compared to the visual analysis. This rapid assessment of a cardiac acquisition window may be most helpful for MRCA, especially when aiming at 3-dimensional coverage of the whole coronary arterial tree during a single scan.
Adult↗
Clinicopathologic features of nephrogenic rests and nephroblastomatosis.
Nephrogenic rests are the consequence of residual metanephric tissue in a fully developed kidney. They usually occur along the perimeter of a mature renal lobe (i.e., perilobar), within the lobe itself (i.e., intralobar), or both (i.e., combined). Nephrogenic rests can be grossly obvious or microscopically discrete. Nephroblastomatosis designates nephrogenic rests that are multifocal or diffuse, and implies more extensive disease. Universal (panlobar) nephroblastomatosis denotes complete replacement of the renal lobe by nephrogenic tissue. The fate of nephrogenic rests and nephroblastomatosis varies and includes obsolescence, sclerosis, dormancy, hyperplasia, or neoplasia. Evidence strongly suggests that neoplastic transformation of nephrogenic rests results in Wilms' tumor (nephroblastoma). Nephrogenic rests almost always occur in the setting of Wilms' tumor; perilobar rests show a strong association with synchronous bilateral Wilms' tumors, whereas intralobar rests are more strongly associated with metachronous tumors. Genetic studies have shown that nephrogenic rests often share many of the same chromosomal defects as Wilms' tumor, which provides further evidence that they are precursors to nephroblastoma. Thus, nephrogenic rests are recognized as clinically significant entities requiring adequate detection and close surveillance. Heightened awareness regarding the clinical relevance of nephrogenic rests and nephroblastomatosis (1) has led to improved detection of these precancerous lesions, (2) fostered more intensive investigation into their biologic behavior, and (3) initiated in-depth discussions about potentially new treatment regimens. The pathologists' ability to identify and detect nephrogenic rests has benefited from the more efficient Beckwith classification. Radiologists have deployed high-resolution radiologic/imaging modalities to improve detection of nephrogenic rests in situ. Clinicians and surgeons are more aware of the impact that nephrogenic rests have upon patient management. Despite this progress, more data is needed to further define these lesions.
Humans↗