Determinants of the tension-time index of inspiratory muscles in children with cystic fibrosis

1. Hypertension secondary to renal disease was studied in non-pregnant and pregnant ewes to determine whether there were any changes in arterial pressure and the distribution of cardiac output and, in particular, whether uteroplacental blood flow was affected. 2. In six non-pregnant, chronically catheterized, uninephrectomized ewes, a reduction in renal blood flow (RBF) to 40-50% of control caused hypertension within 3 h. This was maintained for as long as RBF was reduced (72 h) and returned to control 24 h after the occluder around the renal artery was released. When this experiment was repeated in 16 uninephrectomized pregnant ewes (118-134 days gestation) hypertension occurred within 3 h and was sustained for as long as RBF was reduced (between 24 and 72 h). Arterial pressure returned to control within 24-72 h of restoring RBF. 3. Compared with non-pregnant ewes, pregnant ewes had similar arterial pressures, higher cardiac outputs (CO; P < 0.001) and heart rates (HR; P < 0.001), lower total peripheral resistances (TPR; P < 0.001) and similar blood flows to brain, ovary, pancreas, kidney and spleen. Splenic vascular resistance (VR) was greater (P = 0.006), gut blood flow was greater (P < 0.05) and gut VR was less (P < 0.05). Myoendometrial blood flow/g was greater (P < 0.005) and myoendometrial VR was less (P = 0.006). 4. In pregnant sheep with renal clip hypertension, there was no change in CO and HR, but TPR increased (P < 0.01), as did plasma renin activity. Gut, brain, pancreatic and myoendometrial VR were increased as long as RBF was reduced; in addition, myoendometrial VR remained high for the rest of the experiment. Placental blood flow was unchanged at 3 h; 24-72 h later it was reduced (P < 0.05) and remained low. Placental VR was increased 24-72 h after RBF was restored when ewes were again normotensive. 5. Thus, one-clip, one-kidney renal hypertension in the pregnant ewe was due to increased TPR associated with a fall in uteroplacental blood flow that persisted even when RBF was restored and ewes were normotensive. This reduction in uteroplacental blood flow could account for the high foetal morbidity and mortality that occurs in pregnant women with renovascular hypertension.     

Spontaneous resolution of p58/EB6 antigen restricted NK-type lymphoproliferative disease of granular lymphocytes: role of Epstein Barr virus infection

OBJECTIVE: This study compared late-pregnant radial uterine arteries that supplied the placenta versus the myoendometrium to evaluate differences in active and passive mechanical properties. STUDY DESIGN: Pressurized segments of placental versus myoendometrial radial uterine arteries from late-pregnant (day 28 to 30) New Zealand White rabbits (n = 12) were compared in vitro for differences in luminal diameter, wall thickness, distensibility, and intrinsic tone as a function of transmural pressure. RESULTS: Both types of arteries responded to increased transmural pressure with active vasoconstriction; however, the amount of tone present in myoendometrial arteries was significantly greater than in placental arteries (percent tone at 75 mm Hg = 39% +/- 3% for myoendometrial versus 31% +/- 2% for placental arteries, p < 0.01). Measurements of unpressurized, fully relaxed arteries revealed that placental arteries were 38% larger in diameter and had thicker walls than myoendometrial arteries did. However, myoendometrial arteries were significantly more distensible at transmural pressures >5 mm Hg. CONCLUSIONS: The increased size and diminished tone of placental compared with adjacent myoendometrial arteries would favor increased blood flow to the placenta; differences in size and passive mechanical properties suggest that a localized factor(s) originating from the fetus or placenta contributes to the gestational enlargement of those arteries that perfuse the placenta.     

Occupational status, family environments, and adolescents' aspirations: The Laosa model.

L. M. Laosa (see record 1983-11265-001) suggested a theoretical model in which parent–child interactions are a mediating variable between social-status indicators and children's attributes. The present study examined relationships between family learning environments and the aspirations of 512 Australian adolescents from 3 occupational status groups. Family environments were assessed initially when the adolescents were 11 yrs old, and measures were obtained from parents of their aspirations for their children and their instrumental and affective orientations toward learning. When the adolescents were 16 yrs old, their perceptions of the support for learning provided by their parents were measured. Regression surfaces were constructed from models that included terms to account for possible linear, interaction, and curvilinear associations among the variables. Adolescents' aspirations generally had moderate associations with parents' aspirations but only modest or negligible relations to parents' instrumental and affective orientations. Although occupational status had only modest or negligible associations with the environment and aspiration scores, results indicate that within the different occupational groups the environmental variables combined to have variable patterns of linear, interaction, and curvilinear relationships with adolescents' aspirations. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hand dominance and scoliosis in Duchenne muscular dystrophy

Twenty-three patients with Duchenne muscular dystrophy and scoliosis were studied. In all but one patient the major convexity was to the side of the dominant hand. The unsupported growing spine is easily unbalanced by asymmetrical forces imposed on it. From our observations we believe major use of a single upper extremity will result in scoliosis with the major convexity toward the side of the dominant hand. Management should include counterbalancing the postural abnormality imposed by hand dominance as well as unloading the spine frequently during the patient's waking hours.     

Vasomotor responses of soleus feed arteries from sedentary and exercise-trained rats

Our goals were to determine the nature of endothelium-dependent and -independent vascular responses in isolated soleus feed arteries (SFA) and to test the hypothesis that these responses would be altered by exercise training. Exercise-trained rats ran 30 m/min, up a 15% grade, 1 h/day, 5 days/wk for 10-12 wk, while sedentary control rats were confined to normal cage activity. SFA were isolated, cannulated, and pressurized at 90 cmH2O. After a 1-h equilibration period, the dose-response relationships to constrictors, endothelium-dependent dilators, and endothelium-independent dilators were examined. SFA developed spontaneous tone, demonstrated myogenic reactivity by maintaining vessel diameter in the face of large changes in intraluminal pressure, and constricted in a dose-dependent manner to norepinephrine and potassium chloride. SFA dilated in a dose-dependent manner to the endothelium-dependent dilators acetylcholine and increased flow and to the endothelium-independent dilator sodium nitroprusside. SFA did not dilate to the putative endothelium-dependent dilators bradykinin, substance P, and clonidine or to adenosine. Dilation to acetylcholine was attenuated markedly by arginine analogs and less by 20 mM KCl, but it was unaltered by indomethacin. These results indicate that SFA respond to a number of vasoactive substances, consistent with the hypothesis that SFA participate in the control of vascular resistance. However, exercise training does not appear to elicit a stimulus adequate to alter vasomotor responses in SFA.     

Influence of cardiovascular risk status on coronary flow reserve in healthy young men

To detect changes in vascular physiology associated with early atherosclerosis, we studied whether alterations in coronary flow reserve, as assessed by positron emission tomography imaging with intravenous dipyridamole, would be related to risk factor variables in healthy young men. The number of conventional risk variables correlated significantly with coronary flow reserve (r = -0.58, p = 0.0007), suggesting that alterations in functional vascular reactivity are related to the cardiovascular risk status already in healthy young men.     

Rotational state populations in 16O+154Sm near-barrier fusion

Spaceflight induces a cephalad redistribution of fluid volume and blood flow within the human body, and space motion sickness, which is a problem during the first few days of spaceflight, could be related to these changes in fluid status and in blood flow of the cerebrum and vestibular system. To evaluate possible changes in cerebral blood flow during simulated weightlessness, we measured blood velocity in the middle cerebral artery (MCA) along with retinal vascular diameters, intraocular pressure, impedance cardiography, and sphygmomanometry on nine men (26.2 +/- 6.6 yr) morning and evening for 2 days during continuous 10 degrees head-down tilt (HDT). When subjects went from seated to head-down bed rest, their heart rate and retinal diameters decreased, and intraocular pressures increased. After 48 h of HDT, blood flow velocity in the MCA was decreased and thoracic impedance was increased, indicating less fluid in the thorax. Percent changes in blood flow velocities in the MCA after 48 h of HDT were inversely correlated with percent changes in retinal vascular diameters. Blood flow velocities in the MCA were inversely correlated (intersubject) with arterial pressures and retinal vascular diameters. Heart rate, stroke volume, cardiac output, systolic arterial pressure, and at times pulse pressure and blood flow velocities in the MCA were greater in the evening. Total peripheral resistance was higher in the morning. Although cerebral blood velocity is reduced after subjects are head down for 2 days, the inverse relationship with retinal vessel diameters, which have control analogous to that of cerebral vessels, indicates cerebral blood flow is not reduced.     

Ambient temperature and violent crime: Tests of the linear and curvilinear hypotheses.

Laboratory research on the effects of temperature has led P. A. Bell and R. A. Baron (see record 1976-27853-001) to propose a curvilinear model relating negative affect and aggression. Two alternative explanations, one artifactual and the other based on attributions for arousal, are presented that predict a linear relationship between temperature and aggression in real-world settings. Two studies examining the relation of violent crime to ambient temperature over 90 summer days in Chicago and over a 2-yr period in Houston both yielded linear relationships and revealed significant day-of-the-week effects. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of partial liquid ventilation with perfluorocarbons on pressure-flow relationships, vascular compliance, and filtration coefficients of isolated blood-perfused rabbit lungs

OBJECTIVES: The density of perfluorocarbons is almost twice that of blood. Therefore, we hypothesized that partial liquid ventilation with these fluids markedly affects pulmonary hemodynamics and filtration coefficients. To test these hypotheses we studied pressure-flow relationships, vascular compliances, capillary pressures, and filtration coefficients in normal and perfluorocarbon-ventilated rabbit lungs. DESIGN: Controlled animal study with an ex-vivo isolated lung preparation. SETTING: Research laboratory for experimental anesthesiology at the Heinrich-Heine-University of Düsseldorf. SUBJECTS: Fourteen New Zealand White rabbits. INTERVENTIONS: The lungs were perfused under zone 3 flow conditions with autologous blood at various flow rates (50 to 250 mL/min, closed circuit, roller pump, 37 degrees C) and ventilated with 5% CO2 in air (positive end-expiratory pressure: 2 cm H2O, tidal volume: 10 mL/kg, respiratory rate: 30 breaths/min) without (control group, n=7) and with (n=7) perfluorocarbon administered intratracheally (15 mL/kg). MEASUREMENTS AND MAIN RESULTS: Pulmonary arterial, left atrial, and airway pressures, as well as blood reservoir volume (reflecting changes in pulmonary blood volume) and lung weight, were measured continuously. Inconsistent with our hypothesis, we found no significant differences between both groups in the slopes and intercepts of the pressure-flow relationships. There were no significant differences in capillary pressures determined by double occlusion (6.7+/-1.2 vs. 6.3+/-1.3 cm H2O for control group, p=.53), vascular compliances (0.51+/-0.10 vs. 0.47+/-0.09 mL/cm H2O for control group, p=.38), and filtration coefficients (0.33+/-0.06 vs. 0.37+/-0.07 mL/min/mm Hg/100 g wet weight for control group, p=.80, Mann-Whitney). CONCLUSIONS: Partial liquid ventilation with perfluorocarbons has no relevant effects on pulmonary filtration coefficients and global hemodynamic variables of isolated zone 3 lungs. These findings suggest that right ventricular afterload is not changed with partial liquid ventilation. It is likely, however, that intrapulmonary blood flow is redistributed toward less-dependent regions, although relevant global hemodynamic changes are absent during partial liquid ventilation.     

Rethinking the effects of stressors: A longitudinal study on personal initiative.

This study examined the relationship between stressors at work and personal initiative (PI), one proactive concept of extra-role performance. Using a control theory framework to describe the stress process, the authors hypothesized that stressors should be positively related to PI. This departs from findings of negative relationships between stressors and other types of performance. Furthermore, curvilinear relationships were tested. The analyses, based on 4 measurement waves of a longitudinal field study with 172 to 193 participants, showed that stressors were positively related to subsequent changes in PI; there was no support for a curvilinear relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antioxidants in the respiratory system

BACKGROUND: Reactive oxygen species can participate in the airways reactivity changes after oxidants. The authors have observed an increase in airways reactivity after an exposure to toluene in guinea-pigs and cats in previous experiments. There literature data provide information on the prevention or the delay of free radical damage by antioxidants. MAIN PURPOSE: The aim of our study was to evaluate the effect of nonenzymatic antioxidants--vitamin C and vitamin E on the airways reactivity changes after the exposure to toluene vapours. METHODS: After a one-month-lasting pretreatment with 500 mg/kg/day vitamin C and 50 mg/kg/day vitamin E the guinea-pigs were exposed to toluene for 3 days 2 hours. Then the reactivity of trachea and lung strip smooth muscle to histamine was evaluated. RESULTS: The pretreatment with vitamin C did not evoke statistical significant changes of trachea and lung strip smooth muscles reactivity when compared with the control group. The pretreatment with vitamin E produced a statistically non-significant decrease in trachea smooth muscle reactivity, but an increase in contraction amplitude of lung strip smooth muscle. Trachea was without expressive histological changes. The lung showed granulomatous inflammation with lymphocytes and eosinophils. SUMMARY: Antioxidants in used doses did not prevent the reactivity changes evoked by toluene exposure. (Fig. 2, Tab. 4, Ref. 14.)     

Stabilities underlying changes in interpersonal attraction.

Week-to-week changes in interpersonal attraction on the part of 2 17-man populations of initial strangers were observed over a 4-month period. These and 2 other kinds of responses (S's attitudes toward various objects, and estimates of one anothers' attitudes) showed individual changes during this period. From first to last, however, there persisted a preference for psychologically balanced relationships among the 3 kinds of "elements." This psychological constancy helps to account for the nature of the observed changes. Since accuracy of estimates increased with acquaintance, balance increasingly characterized actual as well as judged relationships. Subgroup formation is interpreted in terms of psychological and objective balance, as constancies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrastructural changes in the interstitial cells of the kidney medullary substance in suckling rabbits with experimental cholera

A culture of virulent selection of cholera vibrios L-top 5879 was introduced through the probe to suckling rabbits-pups 10 to 12 days old. Ultrastructural changes of interstitial cells and capillaries of kidney medulla were studied. During vibrio adhesion (4 hrs after the inaction) interstitial cells acquire dystrophic changes, lipid granules content reduces, while vascular permeability grows higher which suggests the presence of prostaglandin precursors elimination into blood flow. Cholera development (1-2 days later) is accompanied with progressing of signs of prostaglandin synthesis activation and their precursors passage into the vascular bed.     

Perceived racism and vascular reactivity in black college women: Moderating effects of seeking social support.

This quasi-experimental study explored the association of perceived racism and seeking social support to vascular reactivity in a college sample of 110 Black women. Perceived racism and seeking social support were assessed via self-report, and vascular reactivity was measured before and during a standardized speaking task. Hierarchical regression analyses indicated that perceived racism was positively related to changes in systolic blood pressure. These analyses also indicated that seeking social support moderated the relationship between perceived racism and systolic blood pressure changes. This interaction effect persisted after controlling for several potential confounders. Follow-up regression analyses showed that perceived racism was positively associated with reactivity among participants who were low in seeking social support. A significant relationship was not observed between perceived racism and systolic blood pressure changes among participants who were high in seeking social support. Perceived racism and seeking social support were not significantly associated with changes in diastolic blood pressure. These findings highlight the importance of examining psychosocial factors that may mitigate the hypothesized relationship between perceived racism and reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pulmonary vascular resistance of children treated with nitrogen during early infancy

BACKGROUND: We have empirically used supplemental nitrogen in newborns with a functional single ventricle and ductal-dependent systemic perfusion to prevent pulmonary vasodilation and deliver a greater proportion of flow to the systemic circulation. Thus, we reviewed patient outcome to determine whether adverse pulmonary vascular effects may be associated with this therapy. METHODS: From December 1991 to December 1995, the fraction of inspired oxygen was adjusted, with supplemental nitrogen if necessary, to maintain an oxygen saturation near 75% in 20 newborns awaiting heart transplantation. Medical records were reviewed to evaluate (1) the duration of nitrogen therapy, (2) pulmonary vascular histology, (3) postoperative pulmonary hemodynamics, and (4) survival. RESULTS: Thirteen patients underwent heart transplantation, 4 patients died without surgical intervention, and 3 patients underwent late aortic reconstruction. Supplemental nitrogen was used without exceeding a fraction of inspired oxygen of 0.21 for 38 +/- 6 days. One patient had evidence of changes of potentially irreversible pulmonary vascular disease. Pulmonary vascular resistance was not increased long-term in surviving patients. CONCLUSIONS: Supplemental nitrogen can be used to maintain a systemic oxygen saturation near 75% for an extended period in newborns with ductal-dependent systemic perfusion with no long-term adverse effect on pulmonary vascular resistance.     

The importance of the Doppler angle

We examined 118 infrainguinal grafts (103 patients) to determine the effect changes in the angle of theta or Doppler angle had on the accuracy of velocity measurements made with a duplex scanner. Four separate measurements of peak velocity were made on each graft. Three measurements were made with the flow toward the probe at 60 degrees, 50 degrees, 120 degrees (60 degrees the other way). The probe was then turned 180 degrees so the flow was away from the probe and measurements were made at 60 degrees. When the primary cursor was aligned with the vessel wall (Technologist A), the mean velocity at 60 degrees was 69.4 cm/sec and 57.3 cm/sec at 50 degrees, a difference of 12 cm/sec. The same measurements done by Technologist B (primary cursor non aligned with the wall), showed a 10 cm/sec difference (60.7 and 50.5). We saw a consistent difference with even this small difference in the angle of theta throughout the study. The mean velocity obtained by Technologist A when the flow was toward the probe was 61.7. When the probe was turned 180 degrees (flow away from the probe), the mean velocity was 60.5. The same measurements by Technologist B were 51.8 and 50.5. This indicates that the direction of the flow of blood towards or away from the probe does not effect the velocity measurements. Using the vessel wall to line up the primary cursor provides a consistent and easily reproducible reference point to compare measurements made on different days but is less important for single measurements.     

Interpersonal Control Strivings and Vulnerability to Negative Social Exchanges in Later Life.

Although negative social exchanges detract from well-being, little is known about the factors that influence older adults' vulnerability to such exchanges. Interpersonal control strivings were examined as predictors of 2 dimensions of vulnerability to negative social exchanges, exposure and reactivity, in a nationally representative sample of older adults (N = 916). Interpersonal control strivings refer to people's efforts to maintain harmony in their relationships and, when unsuccessful, to preserve their emotional health. The results revealed that interpersonal control strivings directed toward maintaining harmony were associated with less exposure, whereas interpersonal control strivings directed toward preserving emotional health when harmony is threatened were associated with less reactivity. Thus, complementary control processes play an important role in older adults' vulnerability to negative social exchanges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

圆筒型冶金反应器内非轴对称流动的数值模拟

用新开发的同位网格适体坐标程序来描述圆筒型冶金反应器内非轴对称流动,从而回避了柱坐标下极点奇异性问题.数值模拟结果与实验结果对比表明:新开发的程序是可靠的,用该程序对单点偏心底吹氩气搅拌钢包炉(LF)的喷嘴位置进行优化,结果表明:当喷嘴布置在r/R=0.333处时,LF内钢液流动结构最合理,这与实际生产是相符的.     

Fetal endocrine responses to chronic placental embolization in the late-gestation ovine fetus

OBJECTIVE: The purpose of this study was to examine the effect of chronic fetal placental embolization on the fetal corticotropin, cortisol, and catecholamines concentrations and on myometrial contractility pattern. STUDY DESIGN: Fourteen fetal sheep were studied (seven embolized, seven controls) for 10 days between 0.84 and 0.91 of gestation. Daily injections of nonradioactive microspheres were performed to decrease fetal arterial oxygen content by 30% to 35% of the preembolization value. Umbilical artery Doppler flow velocity waveforms were measured daily. RESULTS: Chronic fetal placental embolization produced progressive fetal hypoxemia (p < 0.001) with changes in umbilical artery Doppler flow velocity waveforms indicative of a 25% increase in placental vascular resistance (p < 0.01). In response to chronic fetal hypoxemia there was a progressive increase in baseline fetal plasma norepinephrine concentration (p < 0.001). There was a transient fourfold to fivefold increase in baseline fetal plasma cortisol levels concomitant with a significant decrease in baseline immunoreactive corticotropin between days 7 and 9 of embolization (both p < 0.05), with a return to control values by day 10. There was a 57% increase in myometrial contracture frequency in the embolized group when compared with controls (p = 0.001). CONCLUSIONS: During repetitive chronic placental damage that led to fetal hypoxemia, the fetal endocrine environment changed with time in a direction that would prevent the onset of premature activation of the hypothalamic-pituitary-adrenal axis and premature delivery.     

Deposition and retention of radiolabeled serum constituents in hair after systemic administration

We investigated the relationship between the changes in the pulmonary blood flow and histology during acute rejection following single lung transplantation. In single lung transplantation using adult mongrel dogs, immunosuppression with cyclosporine and azathioprine was discontinued after postoperative day 14 to induce rejection. Doppler flow probes were placed adjacent to the ascending aorta and the left pulmonary artery to measure the blood flow on a daily basis. In addition, chest roentgenograms were also examined daily. The pulmonary pressure was measured using a Swan-Ganz catheter prior to and following the induction of rejection. Open lung biopsies were performed when the left pulmonary artery flow decreased to half of the prerejection value. The pulmonary artery flow decreased to 14.3% of the aortic flow 5 days after the discontinuation of immunosuppression. The graft pulmonary vascular resistance increased significantly compared to the prerejection values (P < 0.001). This was not accompanied by any abnormalities on chest roentgenography. The histology was consistent, with marked perivascular lymphocytic infiltration with little alveolar or interstitial changes. During rejection, the increased pulmonary vascular resistance in the graft was probably the result of perivascular inflammatory cell infiltration, which was seen prior to changes on chest roentgenography. Changes in the left pulmonary artery flow and histology thus appear to be closely correlated in the early stages of acute rejection.