Search PubMed⌕ Search

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.

At least 595 records · Page 33Linked to original sources
PubMed2003

Effect of hydration and vocal rest on the vocal fatigue in amateur karaoke singers.

Karaoke singing is a very popular entertainment among young people in Asia. It is a leisure singing activity with the singer's voice amplified with special acoustic effects in the backdrop of music. Music video and song captions are shown on television screen to remind the singers during singing. It is not uncommon to find participants singing continuously for four to five hours each time. As most of the karaoke singers have no formal training in singing, these amateur singers are more vulnerable to developing voice problems under these intensive singing activities. This study reports the performance of 20 young amateur singers (10 males and 10 females, aged between 20-25 years) on a series of phonatory function tasks carried out during continuous karaoke singing. Half of the singers were given water to drink and short duration of vocal rests at regular intervals during singing and the other half sang continuously without taking any water or rest. The subjects who were given hydration and vocal rests sang significantly longer than those who did not take any water or rest. The voice quality, as measured by perceptual and acoustic measures, and vocal function, as measured by phonetogram, did not show any significant changes during singing in the subjects who were given water and rest during the singing. However, subjects who sang continuously without drinking water and taking rests showed significant changes in the jitter measure and the highest pitch they could produce during singing. These results suggest that hydration and vocal rests are useful strategies to preserve voice function and quality during karaoke singing. This information is useful educational information for karaoke singers.

Adult↗
PubMed2000

Marked weight reduction lowers resting and exercise blood pressure in morbidly obese subjects.

Obesity and high blood pressure (BP) often coexist. Weight reduction lowers resting BP but its effect on BP during exercise (a predictor of target organ damage) has not been evaluated. Blood pressure was measured at rest and during cycling, before and after weight reduction induced by gastric restriction. Nineteen subjects (4 male), 41 +/-2 (SEM) years of age and body mass index (BMI) of 43 +/- 0.9 kg/m2, were studied. On each occasion BP was measured at rest, at a steady state of 0 and 25 watts, at peak exercise and 1 min into recovery. Body weight was reduced by 28% +/- 6% and BMI decreased from 43.3 +/- 0.9 to 31.5 +/- 0.7 kg/m2 (P < .01). Both BP and heart rate, at rest and at all exercise intensities, were significantly lower after weight reduction. Resting BP decreased from 133 +/-4/87 +/- 3 mm Hg to 115 +/- 4/77 +/- 2 mm Hg (P < .001), and BP at peak exercise decreased from 181 +/- 8/98 +/- 4 to 162 +/- 6/83 +/- 5 mm Hg (P < .001). The change in resting systolic BP did not correlate with the change in body weight or with the change in heart rate, but it correlated with the baseline systolic BP (R = 0.61; P < .005). It is concluded that marked weight reduction reduces BP at rest and at all exercise intensities. Gastroplasty should be considered as an option in morbidly obese hypertensive patients who are not well controlled with conventional treatment, and who fail to lose or to maintain a reduced weight by calorie restriction alone.

Adult↗
PubMedDate not supplied

Relation of myocardial perfusion at rest and during pharmacologic stress to the PET patterns of tissue viability in patients with severe left ventricular dysfunction.

BACKGROUND: Stress perfusion imaging can assess effectively the amount of jeopardized myocardium, but its use for identifying underperfused but viable myocardium has yielded variable results. We evaluated the relation between measurements of myocardial perfusion at rest and during pharmacologic stress and the patterns of tissue viability as determined by positron emission tomographic (PET) imaging. METHODS AND RESULTS: We studied 33 patients with coronary artery disease and left ventricular (LV) dysfunction (LV ejection fraction, 30%+/-8%). PET imaging was used to evaluate regional myocardial perfusion at rest and during pharmacologic stress with [13N]-ammonia as a flow tracer, and to delineate patterns of tissue viability (i.e., perfusion-metabolism mismatch or match) using [18F]-deoxyglucose (FDG). We analyzed 429 myocardial regions, of which 229 were dysfunctional at rest. Of these, 30 had normal perfusion and 199 were hypoperfused. A severe resting defect (deficit >40% below normal) predicted lack of significant tissue viability; 31 of 35 regions (89%) had a PET match pattern denoting transmural fibrosis. Although regions with mild or moderate resting defects (deficit <40% below normal) showed evidence of metabolic activity, perfusion measurements alone failed to identify regions with PET mismatch (reflecting hibernating myocardium). Reversible stress defects were observed with slightly higher frequency in regions with a PET mismatch (10 of 37) than in those with a PET match (36 of 162) pattern of viability. A reversible stress defect was a specific (78%) marker, but was a relatively insensitive marker (27%) of viable myocardium as defined by the PET mismatch pattern. CONCLUSIONS: In patients with LV dysfunction, the severity of regional contractile abnormalities correlates with the severity of flow deficit at rest. Severe reductions in resting blood flow in these dysfunctional regions identify predominantly nonviable myocardium that is unlikely to have improved function after revascularization. Although dysfunctional myocardium with mild to moderate flow reductions contains variable amounts of viable tissue (as assessed by FDG uptake), flow measurements alone do not distinguish between regions with PET mismatch (potentially reversible dysfunction) and PET match (irreversible dysfunction). The presence of an irreversible defect on stress imaging is a relatively specific (78%) marker of PET match, whereas a reversible stress defect is a rather insensitive (27%) marker of viability, as defined by the PET mismatch pattern.

Aged↗
PubMed1999

Endothelium-dependent hyperpolarization in resting and depolarized mammary and coronary arteries of guinea-pigs.

1. The membrane potential responses in guinea-pig coronary and mammary arteries attributable to endothelium-derived nitric oxide (NO), prostaglandin (PG) and hyperpolarizing factor (EDHF), and to exogenous NO and the prostacyclin analogue, iloprost, were compared at rest and when depolarized with the thromboxane analogue, U46619. 2. In the coronary artery, stimulation of the endothelium with acetylcholine (ACh) evoked hyperpolarization attributable to NO and a PG with similar pD2s at rest and in the presence of U46619. However, in depolarized tissues, the pD2 of the response attributed to EDHF required a 10 fold lower concentration of ACh compared with at rest. 3. In the mammary artery, lower concentrations of ACh were required to evoke NO- and EDHF-dependent hyperpolarizations in depolarized mammary artery compared with at rest, while PG-dependent hyperpolarization did not occur until the concentration of ACh was increased some 10 fold both at rest and in U46619. 4. The smooth muscle of the coronary artery of guinea-pigs was some 4 fold more sensitive to exogenous NO and iloprost than was the mammary artery. 5. In conclusion, the membrane potential response in arteries at rest, that is, in the absence of constrictor, may be extrapolated to events in the presence of constrictor when NO and PG are under study. However, the sensitivity to ACh and the magnitude of the hyperpolarization attributed to EDHF obtained in tissues at rest may underestimate these parameters in depolarized tissues.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1997

Prediction of resting energy needs in older men with heart failure.

OBJECTIVES: Patients with congestive heart failure are often undernourished. The measurement of resting energy expenditure has served as the basis upon which estimates of daily caloric needs have been developed. Resting energy needs, however, in heart failure patients are unknown. We have developed a new equation to predict resting energy needs in heart failure patients that takes into account easily measured clinical variables and symptom severity. DESIGN: Observational. SETTING: Baltimore VA Medical Center. SUBJECTS: Forty male patients with heart failure aged, 57-85 y; (27 Class II; 13 Class IV). MEASUREMENTS: Resting metabolic rate was measured by indirect calorimetry, fat-free mass and fat mass by dual energy X-ray absorptiometry, peak VO2 by a treadmill test. Symptom severity was measured by the New York Heart Association classification. Ejection fraction, plasma albumin and plasma glucose were also assessed. RESULTS: Stepwise regression analysis showed that body weight, fasting glucose, plasma albumin and New York Heart Association classification accounted for 83% of the variation in resting energy needs. The regression equation had a root mean square error of 130 kcal (544 kJ) per day. The equation is: RMR (kcal/d) = 12.2 (wt, kg) + 1.6 (glucose, gm/dl) + 103 (NYHA; III, IV)-144 (albumin, mg/dl) + 755. Moreover, prediction equations based on observations in healthy individuals significantly underestimated resting energy needs in heart failure patients. CONCLUSION: We offer a new equation to predict resting energy needs in heart failure patients based upon readily available clinical measurements. Further studies are needed to cross-validate our equation.

Absorptiometry, Photon↗
PubMed2001

Measured and predicted resting metabolic rate in Italian males and females, aged 18-59 y.

OBJECTIVES: To determine the resting metabolic rate in a sample of the Italian population, and to evaluate the validity of predictive equations for resting metabolic rate (RMR) from the literature in normal and obese subjects. DESIGN: Cross-sectional observational study. SETTINGS: Department of Human Physiology and Nutrition, University 'Tor Vergata', Rome. SUBJECTS: A total of 320 healthy subjects, 127 males and 193 females, aged 18-59 y. METHODS: Weight, height and resting metabolic rate by indirect calorimetry were measured. Resting metabolic rate was also predicted using equations from the literature. RESULTS: Resting metabolic rate (mean s.d.) in normal weight subjects was 7983+/-1007 kJ/24 h (males) and 6127 907 kJ/24h (females). Measured RMR and predicted RMR values using various equations from the literature were significantly different in males and females, except for the Harris-Benedict equation and the Schofield equations. Also, in overweight and obese subjects the prediction error was generally larger compared to normal-weight subjects for all formulas except for the Harris-Benedict and Schofield formulas. In overweight and obese males but not in females, RMR was lower than in normal-weight subjects after correcting for weight and age differences. Stepwise multiple regression of resting metabolic rate against weight, height and age in males and females did not reveal a prediction formula with a lower prediction error than the Harris-Benedict or Schofield formulas and thus was not further explored. CONCLUSIONS: The Harris-Benedict formula and the Schofield formula provide a valid estimation of resting metabolic rate at a group level in both normal-weight and overweight Italians. However, the individual error can be so high that for individual use a measured value has to be preferred over an estimated value.

Adolescent↗
PubMed1991

Resting energy expenditure in chronic cardiac failure.

1. Resting energy expenditure has previously been shown to be elevated in the acute phase of heart failure, but the situation in the compensated state of chronic cardiac failure is unclear. Resting energy expenditure was assessed in 14 patients with stable chronic cardiac failure and 14 matched control subjects by using indirect calorimetry. 2. Resting energy expenditure was significantly elevated in the patients with chronic cardiac failure (112.6 +/- 18.1 versus 87.1 +/- 12.2 kJ day-1 kg-1 total body weight, P less than 0.0002; mean +/- SD) as were resting O2 consumption (3.88 +/- 0.64 versus 3.00 +/- 0.43 ml min-1 kg-1, P less than 0.0002), ventilation (164 +/- 40.3 versus 104 +/- 16.2 ml min-1 kg-1, P less than 0.0001) and heart rate (85.8 +/- 16.9 versus 66.6 +/- 6.9 beats/min, P less than 0.001). Both the resting plasma concentration of noradrenaline (4.48 +/- 1.52 versus 2.28 +/- 0.96 nmol/l, P less than 0.0001) and the serum concentration of free fatty acids (0.78 +/- 0.21 versus 0.57 +/- 0.27 mmol/l, P less than 0.03) were greater in the patients with chronic cardiac failure. Analysis of covariance indicated that most of the difference in resting energy expenditure could be accounted for by the elevated ventilation in the patients with chronic cardiac failure. Arm muscle area, an index of wasting, was lower in the patients with chronic cardiac failure (39.1 +/- 13.1 versus 50.5 +/- 9.4 cm2, P less than 0.02) and resting energy expenditure was found to account for some of this difference. 3. We conclude that an elevated basal metabolism occurs in chronic cardiac failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1998

A 2-year follow-up of mandibular posture following an increase in occlusal vertical dimension beyond the clinical rest position with fixed restorations.

While resting mandibular posture is continuously changing, repeatable relations of 'physiologic rest position' (PRP) and 'clinical rest position' (CRP) are described in the literature. The PRP is defined as a position of minimal muscle activity and CRP as a more closed clinical reference relation. Relaxed resting posture (RRP) is a repeatable postural range obtained by operator-induced relaxation techniques. This article reports on measurements of mandibular posture in a patient group following an increase in occlusal vertical dimension (OVD) with fixed restorations beyond CRP over 2 years. The relationship of CRP and RRP in the restored and a non-restored control group is compared. The relationship of RRP and corresponding masseteric EMG values to baseline minimal EMG levels is reported for both groups. Resting face height adapted to the increased OVD and remained consistent over 1 and 2 years. The RRP was greater and significantly different from CRP in both groups (P = 0.0001). Results indicated that both CRP and RRP were postural ranges and not specific postural positions. The RRP occurred at minimum baseline EMG levels for both groups and appears to be consistent with physiologic rest position. The possibility of achieving minimal EMG levels at varying interocclusal rest space relations is discussed.

Adaptation, Physiological↗
PubMed2000

Sex, parthenogenesis and genetic structure of rotifers: microsatellite analysis of contemporary and resting egg bank populations.

Cyclically parthenogenetic rotifers are a valuable model for investigating the relationship between reproductive mode and population structure, although advances in this field have been hindered by low allozyme variability in these organisms. A high genotypic diversity is predicted after population establishment, which would be eroded by clonal selection during the parthenogenetic phase. The resting egg bank, produced sexually, is presumed to store high levels of genetic diversity, with subsequent effects on planktonic population structure. Here, we provide the first application of microsatellite markers to a rotifer planktonic population and its associated resting egg bank. Seven polymorphic microsatellite loci were screened in populations of the rotifer Brachionus plicatilis in a temporary pond to analyse: (i) the genetic structure of the resting egg bank; (ii) the changes in the genetic structure of rotifer populations during the parthenogenetic phase; and (iii) the population structure after its initiation from resting eggs. Microsatellites proved to be a useful tool for clone identification, revealing a surprisingly high clonal diversity in rotifer populations. The last sample in the parthenogenetic phase showed evidence of clonal selection, as indicated by a low observed clonal diversity and the appearance of linkage disequilibria. The resting egg bank, analysed comprehensively for the first time in any zooplankter, is in Hardy-Weinberg and linkage equilibrium, and contains a high genotypic diversity. Unexpectedly, the resting egg bank differed from the planktonic population in its allelic composition, suggesting that resting egg hatching is biased.

Animals↗
PubMedDate not supplied

Effect of anti-oxidant treatment and cholesterol lowering on resting arterial tone, metabolic vasodilation and endothelial function in the human forearm: a randomized, placebo-controlled study.

1. The aim of the present study was to determine whether anti-oxidant therapy with vitamin E and/or cholesterol-lowering therapy with simvastatin would augment resting forearm blood flow (FBF) and metabolic vasodilation in response to exercise and improve endothelial function in young patients with hypercholesterolaemia. 2. Endothelium-dependent and -independent, nitric oxide (NO)-mediated vasodilation have been shown to be impaired in young, otherwise healthy subjects with hypercholesterolaemia. Recent experimental and clinical studies suggest that vascular function may be improved with anti-oxidant or cholesterol- lowering therapy, although these treatments may be synergistic. 3. We compared FBF at rest, in response to isotonic exercise, the endothelium-dependent vasodilator acetylcholine (ACh), the endothelium-independent vasodilator sodium nitroprusside (SNP) and the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) in 26 young, otherwise healthy volunteers (mean (+/-SD) age 29+/-7 years; 14 female, 12 male) with hypercholesterolaemia, before and after 6 months treatment with vitamin E, simvastatin and/or placebo. Treatment was randomized, double-blinded in a 2 x 2 factorial design. Forearm blood flow was measured using venous occlusion plethysmography. 4. Vitamin E therapy increased plasma alpha-tocopherol from 39.5+/-9.6 to 75.7+/-33.8 micromol/L (P < 0.001). Simvastatin reduced total cholesterol from 6.9+/-1.7 to 4.9+/-0.8 mmol/L and low- density lipoprotein (LDL) from 4.8+/-1.7 to 3.0+/-0.7 mmol/L (both P < 0.001), although total and LDL-cholesterol also decreased slightly in the placebo group. Vitamin E increased resting FBF from 2.1+/-0.3 to 2.4+/-0.3 mL/100 mL per min (P = 0.04) and decreased resting forearm vascular resistance from 42.1+/-4.2 to 36.1+/-3.4 units (P = 0.01), but the reduction in resting FBF with L-NMMA was not affected. Vasodilation in response to isotonic exercise, ACh and SNP was similar before and after treatment in the placebo, vitamin E, simvastatin and in the combined vitamin E-simvastatin groups. NG-Monomethyl-L-arginine infusion reduced resting FBF and functional hyperaemia in response to exercise and these responses were not altered by treatment. 5. These data suggest that while vitamin E therapy augments resting FBF and reduces forearm vascular resistance in young hypercholesterolaemic subjects, these effects may not be via NO-dependent pathways. Metabolic vasodilation and responses to the NO-mediated vasodilators ACh and SNP were not favourably affected by anti-oxidant or cholesterol-lowering therapy, either alone or in combination.

Adult↗
PubMed2003

Embryonic parathyroid rests occur commonly and have implications in the management of secondary hyperparathyroidism.

BACKGROUND: Recurrence after surgery for secondary hyperparathyroidism is not infrequent. Regrowth of the residual parathyroid tissue after subtotal parathyroidectomy or of the autograft after total parathyroidectomy occurs in many cases. Supernumerary glands are also frequently cited as the offending cause and upon revisiting the neck, the surgeon may be surprised that such an obvious gland was 'missed' at the first operation. Indeed, multiple glands removed in sequential operations have been reported suggesting that they develop over time rather than being present from the start. It is possible that microscopic parathyroid 'rests' of embryological origin proliferate under the ongoing stimulus of renal failure to produce supernumerary glands after apparently adequate initial surgery for hyperparathyroidism. The aim of the present study was to determine whether such rests occur frequently or infrequently. METHODS: Operative details and pathology results from 60 consecutive parathyroidectomies were reviewed and the occurrence of parathyroid rests noted. RESULTS: Parathyroid rests were found in 37% of extra parathyroidal tissues submitted for analysis. These rests were found commonly in the thymus. The potential significance of such parathyroid rests undergoing hyperplasia in response to the ongoing stimulus of renal failure and leading to recurrent hyperparathyroidism is discussed. CONCLUSION: Parathyroid rests are common and potentially serve as a cause of recurrent disease in secondary hyperparathyroidism. Consideration should be given to performing thymectomy as part of the treatment of secondary hyperparathyroidism. A more detailed study is warranted.

Adult↗
PubMed2001

Resting echocardiography and quantitative dipyridamole technetium-99m sestamibi tomography in the identification of cardiac allograft vasculopathy and the prediction of long-term prognosis after heart transplantation.

AIMS: To evaluate the accuracy of echocardiography in conjunction with quantitative high-dose dipyridamole technetium-99m sestamibi tomography (SPECT) in detecting coronary allograft vasculopathy. METHODS AND RESULTS: Seventy-eight consecutive heart transplant recipients underwent echocardiography while at rest and high-dose dipyridamole SPECT within 48 h of a yearly angiogram. Resting wall motion abnormalities were considered significant if present in two or more segments. SPECT was considered abnormal in the presence of reversible/fixed defects. The coronary angiogram was normal in 53, showed non-significant coronary allograft vasculopathy in 13 and significant (> or = 50% stenosis) coronary allograft vasculopathy in 12 cases. Resting wall motion abnormalities were observed in nine cases and perfusion defects in 20. Echocardiography and SPECT were concordant in 59 cases (five positive and 54 negative); in these, accuracy was 100% for significant coronary allograft vasculopathy and 83% for any coronary allograft vasculopathy. Over 6.5+/-2 years, 17 patients suffered coronary allograft vasculopathy-related events, including death in six and retransplantation in three. Resting wall motion abnormalities, SPECT perfusion defects and angiographic coronary allograft vasculopathy were significant predictors of cardiac events. CONCLUSION: Normal resting wall motion at echocardiography coupled to normal stress myocardial perfusion, rules out the presence of significant coronary allograft vasculopathy in many heart transplant recipients. Conversely, resting wall motion abnormalities and perfusion defects strongly predict cardiac events. Therefore, a strategy which reserves angiography for patients with resting wall motion abnormalities and/or perfusion defects may be safe and cost-effective.

Adolescent↗
PubMed2001

The influence of initial resting posture on range of motion of the lumbar spine.

The aim of this study was to investigate the influence of initial resting posture on range of motion of the lumbar spine in 18 normal subjects. Subjects resting posture and active range of motion was measured using the CA-6000 Spinal Motion Analyser (OSI, USA) in five test positions, namely in flat standing and with a variety of heel raises. Analysis showed that there was no significant correlation between subject's normal resting posture and active range of motion. However, when subjects resting posture was artificially altered with heel raises, significant effects on the active range of motion were demonstrated. Increasing heel height significantly influenced resting posture in the sagittal plane only. As heel height increased, the lumbar lordosis decreased and a significant reduction in the range of lumbar spine flexion (P<0.001) was observed. Simulating pelvic asymmetry influenced resting posture in the frontal plane and significant effects on the range of lateral flexion (P<0.05) were observed. These results have important clinical implications in terms of using range of motion of the lumbar spine as an examination tool and suggest that studies using range of motion as an outcome measure should consider initial resting posture.

Adult↗
PubMed1986

Familial dependence of the resting metabolic rate.

Human obesity is known to be a familial disorder. We studied 130 nondiabetic adult southwestern American Indians (74 men and 56 women) from 54 families to determine whether the resting metabolic rate, as measured by indirect calorimetry, is a familial trait that is independent of individual differences in fat-free mass (estimated mass of metabolically active tissue), age, and sex. We found that most of the variance in the resting metabolic rate (83 percent, P less than 0.0001) was accounted for by three covariates--fat-free mass, age, and sex--and that fat-free mass was the most important determinant. Family membership accounted for an additional 11 percent (P less than 0.0001) of the variance in the resting metabolic rate. Thus, resting metabolic rate is a familial trait in this population, and it is independent of differences in fat-free mass, age, and sex. We also found that persons from families with lower resting metabolic rates were no more obese than persons from families with higher metabolic rates. This finding may be partly explained by the close correlation between fat-free mass and percentage of body fat (r = 0.81, P less than 0.0001), which indicates that the resting metabolic rate, as adjusted for fat-free mass, is already partly adjusted for obesity. Only prospective studies will elucidate whether the familial dependence of the resting metabolic rate is a contributing mechanism to the familial predisposition to obesity.

Adolescent↗
PubMed2003

Gene expression and viral prodution in latently infected, resting CD4+ T cells in viremic versus aviremic HIV-infected individuals.

The presence of HIV-1 in latently infected, resting CD4(+) T cells has been clearly demonstrated in infected individuals; however, the extent of viral expression and the underlying mechanisms of the persistence of HIV-1 in this viral reservoir have not been fully delineated. Here, we show that resting CD4(+) T cells from the majority of viremic patients are capable of producing cell-free HIV-1 spontaneously ex vivo. The levels of HIV-1 released by resting CD4(+) T cells were not significantly reduced in the presence of inhibitors of cellular proliferation and viral replication. However, resting CD4(+) T cells from the majority of aviremic patients failed to produce virions, despite levels of HIV-1 proviral DNA and cell-associated HIV-1 RNA comparable to viremic patients. The DNA microarray analysis demonstrated that a number of genes involving transcription regulation, RNA processing and modification, and protein trafficking and vesicle transport were significantly upregulated in resting CD4(+) T cells of viremic patients compared to those of aviremic patients. These results suggest that active viral replication has a significant impact on the physiologic state of resting CD4(+) T cells in infected viremic patients and, in turn, allows release of HIV-1 without exogenous activation stimuli. In addition, given that no quantifiable virions were produced by the latent viral reservoir in the majority of aviremic patients despite the presence of cell-associated HIV-1 RNA, evidence for transcription of HIV-1 RNA in resting CD4(+) T cells of aviremic patients should not necessarily be taken as direct evidence for ongoing viral replication during effective therapy.

Base Sequence↗
PubMed2000

Optimum seat pan and back-rest parameters for a comfortable tractor seat.

An experimental set up was fabricated to measure the pressure distribution on the seat pan and back-rest of a tractor seat. Experiments were conducted with four different seat pans having radius of curvatures of 60, 75, 90 and infinity cm, four back-rests with radius of curvatures of 30, 60, 90 and infinitity cm, and three back-rest inclinations of 0 degrees , 5 degrees and 10 degrees on representative Indian tractor operators. The subjective assessment of perceived comfort at the seat-operator interface was also recorded. Experiments were conducted in a randomized block design and the data obtained were analysed using suitable computer packages. Results indicate that all the parameters, namely seat pan, back-rest profile curvatures and the back-rest angle of inclination, affect the pressure distribution. It is concluded that a seat pan with radius of curvature 75 cm, back-rest with radius of curvature 30 cm and back-rest inclination of 10 degrees are the most suitable parameters for Indian tractor operators.

Adolescent↗
PubMed2004

Actigraphic monitoring of the activity-rest behavior of preterm and full-term infants at 20 months of age.

Differences in the activity-rest behavior of preterm and full-term infants provide an important contribution to the analysis of the ontogeny of circadian rhythms. In this study, we recorded the activity-rest behavior of 17 preterm and 8 full-term infants at the approximate age of 20 months over an average of 10 days by means of actigraphic monitoring (Actiwatch, Cambridge Neurotechnology Ltd.). At the same time, the parents of the infants kept a daily diary. The activity-rest rhythm, the nighttime sleep duration, the daytime rest duration, as well as the sleep quality of the infants were analyzed. Preterm and full-term infants at the age of 20 months show a circadian rhythm with a period length between 23 h 32 min (23:32 h) and 24 h 23 min (24:23 h). It can be concluded that the preterm and full-term infants all reached a vital developmental step by showing the dominant circadian rhythm in the spectrum. The daytime rest duration of preterm infants is significantly shorter than that of full-term infants. The sleep quality of preterm infants is significantly lower than that of full-term infants, which means that the preterm infants have a larger percentage of less restful nighttime sleep. In other studies preterm infants show an over-proportional frequency of attention deficit hyperactivity disorder (ADHD). For this reason, future analyses should reveal whether or not actigraphic monitoring is a suitable means for an early identification of activity-rest behavior in children who may develop ADHD.

Activity Cycles↗
PubMed1976

Changes in RNA in relation to growth of the fibroblast. IV. Alterations in theproduction and processing of mRNA and rRNA in resting and growing cells.

In previous reports, it was shown that both the concentration and rate of production of rRNA and mRNA were greater in growing than in resting 3T6 fibroblasts. Studies on isolated nuclei indicated that ribosomal RNA production is apparently controlled at the level of transcription. In contrast, hnRNA, the putative precursor of mRNA, appeared to be synthesized at the same rate in resting and growing cells. This finding was unexpected and has been tested in several ways. In this report, we show by an independent method that the relative rate of production of mRNA compared to hnRNA is several-fold higher in growing than in resting cells. However, the kinetics of processing of mRNA appear unchanged. This result suggests either that mRNA arises from a small subfraction of hnRNA or that the efficiency of processing of the hnRNA precursor is an important control mechanism which determines mRNA production ingrowing and resting states. Comparison of the initial rates of labeling of hnRNA and cytoplasmic message gives the efficiency with which the cytoplasmic mRNA is produced from nucleoplasmic RNA. The very low efficiency (3-4% in growing and 1-2% in resting cells) suggests that not every hnRNA molecule gives rise to a cytoplasmic message. In contrast to the similar kinetics of mRNA production in resting and growing states, processing of ribosomal RNA is much slower in the resting state and the emergence time for 28S RNA from nucleolus is greatly lengthened.

Cell Division↗