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1-year stability and prediction of cardiovascular functioning at rest and during laboratory stressors in youth with family histories of essential hypertension.

Blood pressure (BP). heart rate, cardiac index, and total peripheral resistance index were measured at rest and in response to postural change, forehead cold stimulation, and a video game challenge in a sample of 128 White and 155 African-American normotensive youth with family histories of essential hypertension (EH). These measurements were readministered 1 year later (12.5 +/- 3.2 months). Moderate temporal stability was observed for all resting and absolute stress responses. Reliability estimates for reactivity change scores were lower, although some were within acceptable ranges. African-American youth exhibited greater BP and peripheral resistance index reactivity to forehead cold on both evaluations. After controlling for various anthropometric and demographic parameters and the pertinent previous year's resting cardiovascular (CV) parameter, mean video game systolic blood pressure (SBP) responses were predictive of resting SBP whereas absolute forehead cold and video game diastolic responses predicted resting diastolic blood pressure (DBP) 1 year later. Mean video game DBP responses were also predictive of resting peripheral resistance index after controlling for significant demographic and anthropometric measures. CV reactivity is discussed with regard to possible value in prediction of changes in resting BP and cardiac structure prior lo establishment of EH.

Journal Article↗

Circulating growth factor studies in growth plate versus resting cartilage in vitro. II. Recognition of growth factors in rat serum.

The growth-promoting effects of GH can be explained in part by the mediation of somatomedins/insulin-like growth factors (IGFs). However, large quantities of the IGFs are required to stimulate growth in vivo, and in some conditions, IGF levels may correlate poorly with GH levels and growth status. These observations suggest that other circulating factors may also be important for growth. We have examined the growth-promoting activity in rat serum, as assessed by stimulation of sulfate and/or thymidine uptake by resting and growth plate cartilage (osteochondral junction) from hypophysectomized rats in vitro. Although stimulation by a low molecular weight somatomedin fraction (approximately 5,000-12,000) accounted for about 90% of serum stimulation of sulfate uptake by resting cartilage, it explained only about 60% of stimulation of the growth plate. Growth plate and resting cartilage appeared equally insensitive to insulin, but the growth plate exhibited reduced sensitivity to inhibitor(s) in diabetic rat serum. Fractionation of normal rat serum by gel filtration at neutral pH revealed comparable stimulation of growth plate and resting cartilage by high molecular weight factors, presumably somatomedins bound to carrier proteins. After gel filtration at acid pH, both growth plate and resting cartilage responded to somatomedins with molecular weights from 5,000-12,000. However, the growth plate also responded to a 12,000-22,000 mol wt factor [Sephadex G-75; 5 X 120 cm; sulfate uptake, 68 +/- 16% above buffer (mean +/- SEM); P less than 0.01] which did not affect resting cartilage (sulfate uptake, 27 +/- 21% above buffer; P = NS). Levels of both the low and higher molecular weight factors were reduced in the serum of hypophysectomized rats. We conclude that circulating growth-promoting activity includes both the low molecular weight somatomedins and a higher molecular weight growth plate growth factor which is not recognized by resting cartilage. Use of the osteochondral junction assay system may permit elucidation of the regulation and nature of this growth factor.

Animals↗

The effects of vitamin D metabolites on the plasma and matrix vesicle membranes of growth and resting cartilage cells in vitro.

This study compares the effects of vitamins 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] and 24,25-(OH)2D3 on populations of chondrocytes at different developmental stages. Confluent third passage chondrocytes derived from the resting zone and adjacent growth region of rat costochondral cartilage were cultured in Dulbecco's Modified Eagle's Medium containing 10% fetal bovine serum and increasing concentrations of hormone. After determination of cell number, matrix vesicles and plasma membranes were isolated by differential centrifugation. The effects of hormone on alkaline phosphatase, 5'-nucleotidase, ouabain-sensitive Na+/K+-ATPase, and phospholipid composition were dependent on vitamin D metabolite and were cell specific. Growth cartilage chondrocytes responded primarily to 1,25-(OH)2D3, whereas resting zone cells responded primarily to 24,25-(OH)2D3. 1,25-(OH)2D3 inhibited growth cartilage cell number at pharmacological concentrations and had no effect on resting cartilage cell number. In contrast, 24,25-(OH)2D3 appeared to stimulate resting cartilage cell number at physiological concentrations and inhibit these cells at pharmacological doses, but had no effect on growth cartilage chondrocytes. These data were supported by [3H]thymidine incorporation studies. 1,25-(OH)2D3 stimulated alkaline phosphatase, 5'-nucleotidase activity, and Na+/K+-ATPase activity in the matrix vesicles of growth cartilage cells. 1,25-(OH)2D3 also stimulated Na+/K+-ATPase activity in the matrix vesicles and plasma membranes of resting zone cells. Incubation with 24,25-(OH)2D3 stimulated alkaline phosphatase, 5'-nucleotidase, and Na+/K+-ATPase in the matrix vesicles produced by resting zone cells. In addition, 24,25-(OH)2D3 stimulated Na+/K+-ATPase activity in the plasma membranes of resting zone cells as well as in both matrix vesicles and plasma membranes of growth cartilage cells.

24,25-Dihydroxyvitamin D 3↗

Production of 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 by growth zone and resting zone chondrocytes is dependent on cell maturation and is regulated by hormones and growth factors.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] and 24,25-(OH)2D3 have been shown to promote chondrocyte proliferation and differentiation; resting zone chondrocytes respond primarily to 24,25-(OH)2D3, whereas growth zone chondrocytes respond primarily to 1,25-(OH)2D3. This study determined whether resting zone and growth zone cells produce 24,25-(OH)2D3 or 1,25-(OH)2D3; whether this production is regulated by 1,25-(OH)2D3 (10(-8) M), 24,25-(OH)2D3 (10(-7) M), dexamethasone (10(-7) M), or recombinant human transforming growth factor-beta 1 (11 ng/ml); and whether the metabolites produced are biologically active. Confluent fourth passage rat costochondral growth zone or resting zone chondrocytes were cultured in Dulbecco's Modified Eagle's Medium containing [3H]25-hydroxyvitamin D3 ([3H]25OHD3), 2% fetal bovine serum, and antibiotics. Metabolism of [3H]25OHD3 was measured by analyzing the lipid extracts of the conditioned medium and the cell layer for [3H]1,25OHD3, [3H]1,25-(OH)2D3, and [3H]24,25-(OH)2D3 using flow-through scintillation spectroscopy of HPLC eluates. Chemically synthesized radioinert vitamin D3 metabolites were used as standards, and their migration was determined by absorbance at 254 nm. To ensure that the radioactive peaks were 1,25-(OH)2D3 and 24,25-(OH)2D3, the fractions were rechromatographed into three other HPLC solvent systems. Biological activity was confirmed; the addition of HPLC-purified 1,25-(OH)2D3 produced by growth zone chondrocytes elicited a dose-dependent stimulation of alkaline phosphatase specific activity in growth zone cell cultures, but had no effect on the resting zone cells. There was a time-dependent increase in both [3H]1,25-(OH)2D3 and [3H]24,25-(OH)2D3 in the conditioned medium of both types of cultures. At 24 h, the percent conversion of [3H]25OHD3 to [3H]1,25-(OH)2D3 was 5.3 +/- 1.2, and the percent conversion to [3H]24,25-(OH)2D3 was 1.8 +/- 0.4 in growth zone chondrocyte cultures. No such effect was found in cultures freeze-thawed five times or without cells. When resting zone cells were cultured with [3H]25OHD3, the percent conversion to 1,25-(OH)2D3 and 24,25-(OH)2D3 was 4.5 +/- 1.0 and 1.7 +/- 0.4, respectively. The addition of dexamethasone significantly increased the percent production of 1,25-(OH)2D3 at 6 and 24 h and at 6 h by resting zone and growth zone cells, respectively, compared to the control values. Recombinant human transforming growth factor-beta 1 increased the percent production of 1,25-(OH)2D3 after 1 h in resting zone cells and, after 24 h, the production of 24,25-(OH)2D3 in growth zone cells. Radiolabeled 1,25-(OH)2D3 and 24,25-(OH)2D3 were not detected in the cell layer.(ABSTRACT TRUNCATED AT 400 WORDS)

24,25-Dihydroxyvitamin D 3↗

Comparative haemodynamic studies of resting and active skeletal muscle in anaesthetised rats: role of nitric oxide.

Our previous studies have indicated that nitric oxide takes part in the basal regulation of vascular tone in skeletal muscle. The purpose of this study was to investigate whether nitric oxide has a role in the active hyperaemic response of a working muscle in a resting subject. Haemodynamic effects of nitric oxide synthase (NOS) inhibition (L-NAME, 10 mg/kg/30 min i.v. infusion) were determined simultaneously in the resting m. quadriceps femoris and in the working (breathing) m. rectus abdominis in anaesthetised rats (86Rb accumulation technique). L-NAME increased blood pressure and total peripheral resistance (TPR) while it decreased cardiac output. Blood flow (BF) decreased and vascular resistance (VR) increased both in resting (BF: 8.91+/-1.97-->5.92+/-2.59 ml/min/100 g, p<0.05: VR: 106+/-29.9-->212+/-113 R, p<0.01) and working (BF: 17.0+/-4.78-->6.93+/-2.15 ml/min/100 g, p<0.001; VR: 57.0+/-18.5-->160+/-56.7 R, p<0.01) muscle following NOS inhibition, but the percentile change of BF was higher in the working muscle (59%) than in the resting one (34%, p<0.001). There was a positive correlation between the cardiac output and the blood flow of the resting muscle with or without L-NAME administration, but blood flow of the working muscle failed to have any correlation with the cardiac output in control animals. However, L-NAME administration decreased both the cardiac output and the blood flow and similarly to the resting muscle a positive correlation was found. In conclusion, the haemodynamic effects of NOS inhibition are higher in working muscle than in the resting one: the nitric oxide may have important role in vasodilatation during muscle activity.

Anesthesia↗

Using forest inventory data to assess fisher resting habitat suitability in California.

The fisher (Martes pennanti) is a forest-dwelling carnivore whose current distribution and association with late-seral forest conditions make it vulnerable to stand-altering human activities or natural disturbances. Fishers select a variety of structures for daily resting bouts. These habitat elements, together with foraging and reproductive (denning) habitat, constitute the habitat requirements of fishers. We develop a model capable of predicting the suitability of fisher resting habitat using standard forest vegetation inventory data. The inventory data were derived from Forest Inventory and Analysis (FIA), a nationwide probability-based sample used to estimate forest characteristics. We developed the model by comparing vegetation and topographic data at 75 randomly selected fisher resting structures in the southern Sierra Nevada with 232 forest inventory plots. We collected vegetation data at fisher resting locations using the FIA vegetation sampling protocol and centering the 1-ha FIA plot on the resting structure. To distinguish used and available inventory plots, we used nonparametric logistic regression to evaluate a set of a priori biological models. The top model represented a dominant portion of the Akaike weights (0.87), explained 31.5% of the deviance, and included the following variables: average canopy closure, basal area of trees <51 cm diameter breast height (dbh), average hardwood dbh, maximum tree dbh, percentage slope, and the dbh of the largest conifer snag. Our use of routinely collected forest inventory data allows the assessment and monitoring of change in fisher resting habitat suitability over large regions with no additional sampling effort. Although models were constrained to include only variables available from the list of those measured using the FIA protocol, we did not find this to be a shortcoming. The model makes it possible to compare average resting habitat suitability values before and after forest management treatments, among administrative units, across regions and over time. Considering hundreds of plot estimates as a sample of habitat conditions over large spatial scales can bring a broad perspective, at high resolution, and efficiency to the assessment and monitoring of wildlife habitat.

Animals↗

Enhanced prognostic stratification of CAD patients with low ejection fraction by stress-rest Tc99m tetrofosmin gated-spect.

OBJECTIVE: This study was performed to assess whether post-stress and rest functional parameters, as measured by gated-SPECT, provide additional predictive value for long-term prognosis, over clinical and perfusion data in patients (pts.) with low left ventricular ejection fraction (LVEF). METHODS: 647 consecutive pts. underwent stress/rest gated-SPECT, and 497 were followed for a mean period of 516 +/- 264 days. Segmental perfusion and motion/thickening (post-stress and rest) were analysed visually, while EF and LV volumes were calculated using an automatic algorithm (QGS). The post-stress and rest ratio were determined for both end-diastolic (EDV) and end-systolic volume (ESV), while the post-stress LVEF change was calculated subtracting rest-EF from stress-EF. RESULTS: 84/497 pts. showed rest EF < 40%, and 15/84 (18%) experienced a cardiac event (3 cardiac deaths, 1 infarction, 3 hospitalized angina and 9 late revascularizations). The perfusion and functional parameters were not significantly more compromised in pts. with cardiac events compared with pts. without events. Post-stress ESV was the only index significantly higher in pts. with low EF and events compared with pts. with low EF without events (150 +/- 72 ml vs. 123 +/- 53 ml, P = 0.02). Univariate Cox analysis of clinical, perfusion and functional data showed that the best predictor of cardiac events was stress-ESV (score 6.5, P = 0.01), followed by rest-ESV, rest-EDV, stress-EDV and stress-LVEF. Multivariate analysis demonstrated that the addition of stress-ESV to stress-EF, yielded a significant increase in the global chi2 in the prediction of hard events (cardiac death/infarction) (score 4.634, P = 0.03). CONCLUSION: In patients with depressed LVEF, stress-ESV was the only independent predictor of long-term outcome.

Adult↗

Resting blood pressure index in arterial occlusive disease of the lower limbs.

The resting blood pressure index of the ankle by the Doppler Ultrasound technique was correlated to the clinical picture and angiographic appearances in 152 legs. A very good correlation existed between the clinical picture and resting pressure index. The latter followed the angiographic status expressed by a score. We could not show any differences between the gropus pains at rest, gangrene or ulceration, either by resting pressure index or by angiographic score. Statistically highly significant differences were found between the resting pressure index and the groups asymptomatic legs, to the intermittent claudication and claudication to pains at rest or gangrene. Irrespective of where the stenosis is localized, the resting blood pressure index of the ankle is the same when the functional status of the patient is the same. This method cannot define the anatomical distribution of occlusive disease; therefore it cannot replace the angiographic examination when there is an indication for reconstructive arterial surgery. However, in the routine assessment, it offers an objective, reproducible and simple method for evaluating the functional effect of occlusive arterial disease in the lower limbs.

Arterial Occlusive Diseases↗

Prognostic value of rest (201)Tl-dipyridamole stress (99m)Tc-sestamibi gated SPECT for predicting patient-based clinical outcomes after bypass surgery in patients with ischemic left ventricular dysfunction.

UNLABELLED: We investigated the postoperative prognostic value of preoperative myocardial SPECT for predicting clinical outcomes, including event-free survival and functional improvement. METHODS: A total of 123 patients with ischemic heart disease and left ventricular dysfunction were enrolled. The ratio of men to women was 103:20, and the mean (+/-SD) age was 61 +/- 8 y. The disease involved 3 vessels in 95 patients, 2 vessels in 27 patients, and 1 vessel in 1 patient. Rest (201)Tl-dipyridamole stress (99m)Tc-sestamibi gated 24-h-delayed SPECT was performed before and 3-4 mo after bypass surgery. With a 20-segment model, a dysfunctional segment was defined as that with systolic wall thickening of <20%. Dysfunctional but viable segments were defined for each viability predictor, including rest thallium uptake of >60%, reversibility score (rest perfusion minus stress perfusion) of >7, systolic wall thickening of >10%, and 24-h-delayed thallium uptake of >60%. Global left ventricular functional improvement was defined as a 5% increase in the left ventricular ejection fraction (LVEF) or a 10-mL decrease in the end-systolic volume (ESV). A long-term follow-up evaluation was performed by chart reviews and telephone interviews over a period of up to 6 y. Cardiac events were defined as cardiac death, myocardial infarction, or heart failure requiring hospitalization. RESULTS: After bypass surgery, the LVEF was improved from 36.4% +/- 8.8% (mean +/- SD) to 44.3% +/- 11.1%, and the ESV was improved from 96.6 +/- 46.7 mL (mean +/- SD) to 75.1 +/- 44.0 mL. Global left ventricular function was improved in 96 patients but not improved in 27. Rest thallium uptake (>or=4 segments) and reversibility (>or=5 segments) were found to be significant variables in the receiver-operating-characteristic (ROC) curve analysis, with area-under-the-curve (AUC) values of 0.755 (P < 0.05) and 0.735 (P < 0.05), respectively. The values for preserved systolic wall thickening and delayed thallium uptake had no statistical significance. Using a multivariate logistic function, we created a single variable consisting of rest thallium uptake and reversibility; this variable had better prediction power than any other single variable (AUC value for the ROC curve, 0.794). Patients with a higher logistic function value (>or=0.84) showed better event-free survival than did those with a lower logistic function value (<0.84) (log-rank test, P < 0.05). CONCLUSION: The number of viable segments should be >4 for rest (201)Tl SPECT or >5 for the reversibility parameter for the prediction of global functional improvement in a patient-based evaluation. With a logistic function created from these parameters, the long-term clinical prognosis after bypass surgery could be predicted by the presence of viability on preoperative rest-stress myocardial SPECT.

Coronary Artery Bypass↗

Sensitivity of whole body protein synthesis to amino acid administration during short-term bed rest.

We tested the hypothesis that a reduced stimulation of whole-body protein synthesis by amino acid administration represents a major mechanism for the bed rest-induced loss of lean body mass. Healthy young subjects and matched controls were studied on the last day of a 14-day bed rest or ambulatory period, as part of the overall protocol "Short-term Bed Rest - Integrated Physiology" set up by the German Aerospace Centre (DLR) in co-operation with the European Space Agency. A balanced mixture of essential and non-essential amino acids was intravenously infused in the postabsorptive state for 3 hours at the rate of 0.1 g/kg/hour. The oxidative and non-oxidative (i.e., to protein synthesis) disposal of the infused leucine was determined by stable isotope and mass spectrometry techniques. The clearance of total infused amino acids tended to be greater (P=0.07) in the ambulatory group than in the bed rest group. When leucine clearance was partitioned between its oxidative and non-oxidative (i.e., to protein synthesis) components, the results indicated that the oxidative disposal was not statistically different in the bed rest and in the ambulatory groups. In contrast, the non-oxidative leucine disposal (i.e., to protein synthesis) was about 20% greater (P<0.01) in the ambulatory group than in the bed rest group. In conclusion, these preliminary data suggest that 14-day bed rest impairs the ability to utilise exogenous amino acids for protein synthesis.

Journal Article↗

[Morphological characteristics of resting eggs produced by different Brachionus calyciflorus].

In this paper, the Qingdao and Wuhu strains of Brachionus calyciflorus were cultured at 20 degrees C, 25 degrees C and 30 degrees C, and fed with 1.0 x 10(6) and 5.0 x 10(6) cells x ml(-1) of Scenedesmus obliquus. The morphological study of their produced resting eggs showed that at the two food concentrations, the resting eggs produced at 20 degrees C were the largest in length, width and volume, while those produced at 25 degrees C and 30 degrees C were the smallest. The effects of strain on the morphological characteristics of resting eggs also depended on food concentration. When the food concentration was 1.0 x 10(6) cells x ml(-1), the length, width and volume of the resting eggs produced by Wuhu strain and Qingdao strain were 156.00 microm, 99.95 microm and 12 269.11 microm3, and 145. 13 microm, 91.97 microm and 10 498. 19 microm3, respectively, while when the food concentration was 5.0 x 10(6) cells x ml(-1), the corresponding values were 155. 68 microm, 100.85 microm and 12 348.59 microm, and 156.63 microm, 98.04 microm and 12 054. 20 microm3, respectively. For test strains, only Wuhu strain showed a marked curvilinear correlation in the length, width and volume of its resting eggs with temperature. At the same temperature, the volumes of the resting eggs produced by both Qingdao and Wuhu strains were increased with increasing food concentration, with the exception that the resting eggs produced by Wuhu strain at 30 degrees C decreased with increasing food concentration.

Animals↗

[Evaluation of stresses in different cingulum rest seats].

Both lingual and incisal rest seats are used on anterior teeth. Lingual rest seats are preferred since they are more acceptable esthetically and located closer to the centre of rotation of the tooth. Lingual rest seats can be prepared directly on the abutment teeth as grooves, shoulders or may require restorations such as crowns, inlays and prefabricated rest seats to provide proper contour. In this study, the stress induced by two conventionally applied rest seats were compared with that of the U shaped rest seats which were recently induced. As a result it is found that more uniform stress distribution occurred in U and inverted "v" type rest seat designs.

Dental Abutments↗

Acute increase in exercise capacity with milrinone: lack of correlation with resting hemodynamic responses.

1. The acute administration of milrinone, a positive inotropic vasodilator agent, improves resting hemodynamic function and maximal and submaximal metabolic responses to exercise in patients with severe congestive heart failure. 2. To determine whether the improvement in exercise capacity induced by milrinone administration can be predicted by its acute positive inotropic and/or vasodilator effects at rest, milrinone was administered intravenously (progressive doses of 12.5 to 75 microns/kg) to 15 patients with heart failure (functional classes III and IV, New York Heart Association) at rest, and during maximal upright exercise testing on a cycle ergometer. Serum drug levels were matched for the resting and exercise tests. Drug administration for exercise tests was placebo-controlled and double-blind. 3. At rest, milrinone administration caused substantial decreases in right atrial pressure (-53%), left ventricular end-diastolic pressure (-30%), and systemic vascular resistance (-35%); and increases in cardiac index (+59%), peak positive dP/dt (+20%) and stroke work index (+51%). Administration of milrinone during exercise resulted in a 15% increase in peak oxygen uptake and a 16% increase in anaerobic threshold. However, none of the changes in resting hemodynamic function correlated significantly in magnitude with the changes in peak oxygen uptake and anaerobic threshold. 4. Thus, the acute improvement in exercise capacity that occurs with milrinone is not predicted by the positive inotropic or vasodilator effects of the drug at rest.

Anaerobic Threshold↗

The effect of training on the norepinephrine response at rest and during exercise in 5 degrees and 20 degrees C environments.

Eleven males were examined at rest and during submaximal exercise in 5 degrees C and 20 degrees C environments to determine if the norepinephrine (NE) and other physiological responses in the cold would be altered by eight weeks of training. Blood samples were obtained at the end of 15 minutes of rest and submaximal exercise, and were assayed for NE. Pretraining resting NE levels in the 5 degrees C condition were significantly higher than those found in the 20 degrees C environment (684 +/- 89 vs 491 +/- 48 pg/ml). A significant training effect reduced resting NE levels in the 5 degrees C (502 +/- 77 pg/ml) but not the 20 degrees C (392 +/- 45 pg/ml) condition. Pre and posttraining exercise NE levels were elevated above resting in both the 5 degrees C (1477 +/- 136 vs 1559 +/- 208) and the 20 degrees C environments (1623 +/- 176 pg/ml vs 1444 +/- 224 pg/ml), but were not significantly different between conditions. Skin temperatures were significantly lower, and resting blood pressure was significantly higher in the 5 degrees C condition. These data suggest that both cold and exercise act as stimulators of NE release, but an additive effect on NE of cold and exercise does not occur. The resting NE levels pre and posttraining in the 5 degrees C condition suggest that a cross tolerance to cold stress was present.

Adaptation, Physiological↗

[Application of cephalometric study of the rest position to diagnosis of reversed occlusion cases].

A cephalometric study of reversed occlusion in the rest position was performed. Materials consisted of cephalograms which were taken from 20 Japanese with reversed occlusion Study was made of the 2 dimensional changes in cephalograms before and after treatment, in order to determine its value for the estimation of the mandibular position after treatment of reversed occlusion, for therapeutic purposes, and also its value as a rotational element in preparation of Ricketts' V.T.O. Superimposed cephalometric tracings were made in the pretreatment and posttreatment rest positions. Using these, the method was evaluated for current use in analysis. The superimposition of tracings enabled estimation of the mandibular position and habitual position with an accuracy of 80% (16/20 cases). Coincidence of posttreatment mandibular position and pretreatment rest position was obtained in all adult cases. Utilization of the rest position for preparation of Ricketts' V.T.O. made it possible to estimate the growth direction and the mandibular position with an accuracy of 65%. Superimposition of pretreatment rest position and posttreatment habitual occlusal position led to coincidence of V.T.O. 84% of the time. Case analysis by means of Rákosi's functional analysis was effective for the determination of the relative therapeutic difficulty and the therapeutic approach. Utilization of the rest position, in addition to Kim's ODI and APDI values proved to be capable of determining the exact therapeutic plan at a probability of 70%. The above results revealed that the preoperative rest position was effective, not only for functional analysis, but also for the estimation of the therapeutic goal for adult cases and of the first stages-completion (at the overjet correction) for young cases.

Cephalometry↗

Calcium shifts accompanying rest-dependent phenomena in atrial muscle of guinea-pig heart.

Calcium shifts accompanying rest and post-rest phenomena in isolated left atrial appendages of guinea-pig heart were investigated by means of isotope 45Ca2+. Experiments were performed under conditions of full equilibration of preparations with isotope-containing solution (at least 45 min) in order to investigate the changes in content of exchangeable Ca, or at short exposure to isotope (2-5 min) in order to measure the excitation-dependent Ca2+ influx. Atria stimulated at the rate of 60/min for 55 min in radioactive solution contained 3.79 +/- 0.21 mM of 45Ca2+/kg of wet weight (w.w.). The rested preparations contained 2.61 +/- 0.23 mM/kg w.w. When the previously stimulated for 45 min atria were allowed to rest for 10 min, their content of 45Ca2+ dropped to 3.01 +/- 0.17 mM/kg w.w. despite continued exposure to this isotope. The first post-rest contraction was by 50% +/- 25% stronger than the control steady-state beats. Contractile force (CF) decreased during the two following beats to 25% of control. Calcium-45 content dropped during these beats to 2.50 +/- 0.14 mM/kg w.w. whereas influx of 45Ca2+ amounted to 0.24 mM/kg w.w. CF recovered to control values during 10 min of the following stimulation. Calcium-45 content reached at this time 4.09 +/- 0.12 mM/kg w.w. It is proposed that there are two intracellular store compartments in guinea-pig atrial muscle. The capacity of one of them is rate-dependent and its Ca2+ is lost at rest. This Ca2+ is partially trapped by the other compartment (presumably sarcoplasmic reticulum) and is released to activate the strong post-rest contraction.

Animals↗

Acute and long-term effects of nitrendipine on resting and exercise hemodynamics in essential hypertension.

The hemodynamic effects of nitrendipine have been studied at rest and during exercise in eight patients with mild to moderate essential hypertension. Acutely, nitrendipine (20 mg) induced at rest a decrease in arterial blood pressure (from 194/100 to 151/78 mm Hg) and an increase in heart rate (from 81 to 101 beats/min); the cardiac output was unchanged and the systemic vascular resistances fell by 30%. Similar changes were observed during exercise, i.e., a decrease in arterial blood pressure (from 245/106 to 204/87 mm Hg) and in systemic vascular resistances (-25%) with an increase in heart rate (from 133 to 142 beats/min). After chronic treatment during 55 days (average daily dose was 46 mg), the hypotensive effects of nitrendipine were similar, although less marked, both at rest and during exercise; the tachycardia noted after acute intake disappeared after chronic therapy. The addition of atenolol (100 mg) at the end of the chronic study in six patients further reduced arterial blood pressure at rest (138/80 mm Hg) and during exercise (180/91 mm Hg); the heart rate decreased to 60 beats/min at rest and 94 beats/min during exercise. These data show that nitrendipine is a potent antihypertensive agent that induces an important fall in the systemic vascular resistances both at rest and during exercise; during chronic therapy, these antihypertensive effects were maintained while the reflex tachycardia disappeared. The addition of atenolol during chronic therapy contributed to the normalization of the resting and exercise arterial blood pressures in nearly all patients.

Adult↗

[DNA synthesis in the nuclei of resting and proliferating cells of the NIH 3T3 line in monokaryons, homo- and heterodikaryons].

Serum-deprived (0.5%) resting NIH 3T3 mouse fibroblasts were fused with stimulated cells taken at 2 hour intervals after changing the medium to the one containing 10% serum, and DNA synthesis was investigated in monokaryons, homodikaryons, and heterodikaryous using radioautography with double-labeling technique. The presence of the resting nucleus in the common cytoplasm has an inhibitory effect on the entry of the stimulated nucleus into the S period in the medium containing either 0.5 or 10% serum, but DNA synthesis continues. After a 24 hour stay in the common cytoplasm with resting nuclei the stimulated nuclei return into the state of rest. When resting cells are stimulated by 10% serum, their inhibitory effect on stimulated nuclei in heterodikaryons still persists for at least 2 hours following stimulation. Preincubation of resting cells with cycloheximide for 4 hours abolishes their ability to suppress DNA synthesis in stimulated nuclei. The data suggest that the resting cells produce an endogenous inhibitor of cell proliferation whose formation depends upon the synthesis of protein(s). When stimulated, cell can proliferate only upon decreasing the level of this inhibitor. The obtained results are consistent with the idea of a negative control of cell proliferation.

Animals↗