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At least 1,549 records · Page 86Linked to original sources
PubMed2003

Inverse amygdala and medial prefrontal cortex responses to surprised faces.

Here we show inverse fMRI activation patterns in amygdala and medial prefrontal cortex (mPFC) depending upon whether subjects interpreted surprised facial expressions positively or negatively. More negative interpretations of surprised faces were associated with greater signal changes in the right ventral amygdala, while more positive interpretations were associated with greater signal changes in the ventral mPFC. Accordingly, signal change within these two areas was inversely correlated. Thus, individual differences in the judgment of surprised faces are related to a systematic inverse relationship between amygdala and mPFC activity, a circuitry that the animal literature suggests is critical to the assessment of stimuli that predict potential positive vs negative outcomes.

Adult↗
PubMed1985

Effect of body inversion on hemodynamics determined by two-dimensional echocardiography.

The purpose of this study was to determine if head-down inversion of normal men from a supine position would increase blood return to the heart. Eight healthy, normovolemic men were placed into 10 degrees, 30 degrees, 60 degrees, and 90 degrees head-down tilt positions. BP and two-dimensional echocardiograms were recorded at the supine baseline and immediately after inversion. There was no significant change in left ventricular end-diastolic volume, stroke volume, cardiac output, or BP with inversion, except for a significant increase in diastolic pressure at the 60 degree position. The efficacy of placing hypotensive shock patients in the head-down tilt position is discussed.

Adult↗
PubMed1995

Pressure-controlled, inverse ratio ventilation that avoids air trapping in the adult respiratory distress syndrome.

OBJECTIVES: To investigate physiologic and outcome data in patients switched from volume-cycled conventional ratio ventilation to pressure-controlled inverse ratio ventilation that did not produce air trapping and intrinsic positive end-expiratory pressure (PEEP). SETTING: Medical intensive care unit. DESIGN: Retrospective analysis of crossover data and outcome. PATIENTS: Fourteen patients with the adult respiratory distress syndrome who were receiving mechanical ventilation with volume-cycled, conventional ratio ventilation followed by pressure-controlled, inverse ratio ventilation. INTERVENTIONS: Our approach to pressure-controlled, inverse ratio ventilation was to use tidal volumes and applied PEEP values comparable to those volumes and values used on volume-cycled, conventional ratio ventilation, use inspiratory times to increase mean airway pressure instead of additional applied PEEP, and avoid air trapping (intrinsic PEEP). MEASUREMENTS AND MAIN RESULTS: With this approach, there was a reduction in peak airway pressure from 53 +/- 8.5 (SD) to 40 +/- 5.9 cm H2O (p < .01), and an increase in mean airway pressure from 20 +/- 3.9 to 30 +/- 5.2 cm H2O (p < .01). Tidal volume, mean inflation pressure, and compliance did not change. Oxygenation (PaO2) improved from 57 +/- 11.3 torr (7.6 +/- 1.5 kPa) to 94 +/- 40.2 torr (12.5 +/- 5.4 kPa) (p = .01) but the oxygenation index (mean airway pressure x FIO2 x 100/PaO2) did not change significantly (25.9 +/- 10.3 to 27.2 +/- 12.2). There was no significant change in PaCO2 or pH even though delivered minute ventilation decreased from 17.4 +/- 4.3 to 14.8 +/- 5.8 L/min (p = .02). Cardiac index slightly decreased, but hemodynamic values were otherwise stable. Only three of the 14 study patients survived. CONCLUSIONS: These data demonstrate that oxygenation is primarily a function of mean airway pressure, and that longer inspiratory times can be used as an alternative to applied PEEP to increase this oxygenation. If no air trapping develops, lung inflation pressures and delivered volumes remain constant with this approach. Because the technique was used only in patients refractory to conventional techniques, the poor outcome is not surprising.

Adult↗
PubMedDate not supplied

MR imaging of uterine inversion.

Inversion of the uterus is a postpartum complication that is an obstetric emergency. This report describes a case of inversion of the uterus in which clinical evaluation was inconclusive, and magnetic resonance (MR) of the pelvis revealed findings virtually pathognomonic of incomplete inversion of the uterus with far greater conspicuity than on corresponding ultrasound. The MR findings directly resulted in earlier therapeutic intervention with a possible decrease in morbidity.

Adult↗
PubMedDate not supplied

Computed tomography of chronic nonpuerperal uterine inversion.

Uterine inversion is an unusual entity; chronic nonpuerperal inversion is rare. In this report we present a case of chronic nonpuerperal uterine inversion that was initially diagnosed as invasive endometrial carcinoma. The CT findings in this case are presented.

Chronic Disease↗
PubMed2004

Brachial artery vasomotor function is inversely associated with 24-h ambulatory blood pressure.

BACKGROUND: Impaired endothelial function has been reported in hypertensive individuals. The extent to which such changes reflect the co-existence of other cardiovascular disease risk factors rather than an independent association with blood pressure remains uncertain. OBJECTIVE: To assess the relationship between brachial artery vasomotor function and ambulatory blood pressure in hypertensive individuals and normotensive controls. METHODS: We assessed 24-h ambulatory blood pressure and brachial artery endothelial and smooth muscle function in 155 patients with hypertension and 40 normotensive controls. The vasomotor functions were determined by ultrasonographic assessment of vasodilator responses to flow and sublingual glyceryl trinitrate, respectively. Patients with hypertension were categorized as either treated (n = 85) or untreated (n = 70), and further subdivided on the basis of either no or at least one other cardiovascular risk factor. These included hyperlipidaemia, smoking, diabetes or a previous coronary or cerebrovascular event. RESULTS: Age- and sex-adjusted flow-mediated and glyceryl trinitrate-mediated responses were not significantly different in hypertensive individuals with respect to treatment status or the presence of risk factors when compared with controls. However, when data from all 195 study participants were pooled, 24-h ambulatory systolic blood pressure was inversely related to flow-mediated response (P = 0.002), and both systolic and diastolic blood pressure were inversely related to glyceryl trinitrate response (P < 0.001 and P = 0.009, respectively). Observed relationships were largely unaltered after further adjustment for body mass index, antihypertensive treatment or the presence of other risk factors. CONCLUSIONS: The finding of a direct and inverse relationship between the level of ambulatory blood pressure and flow-mediated and glyceryl trinitrate responses is consistent with a direct influence of blood pressure on conduit vessel vascular function.

Antihypertensive Agents↗
PubMed1991

The use of pressure-controlled inverse ratio ventilation in the surgical intensive care unit.

A key element in the treatment of Adult Respiratory Distress Syndrome (ARDS) is improvement in oxygen delivery to match metabolic demands. Conventional modes of ventilation have decreased mortality (50%) very little. We have done a retrospective analysis of 30 surgical patients who were treated with pressure-controlled inverse ratio ventilation. Mortality was 10%. Arterial oxygenation improved from 40.8 +/- 12.2 mm Hg to 138 +/- 47.2 mm Hg, while PCO2 decreased from 37.8 +/- 7.6 mm Hg to 31.1 +/- 5.9 mm Hg. Simultaneously, with the use of pressure-controlled inverse ratio ventilation, minute ventilation could be decreased by 30%, which may be secondary to increased O2 delivery to the tissue. Our data indicate that pressure-controlled inverse ratio ventilation may be beneficial to surgical patients with ARDS.

Adolescent↗
PubMed1984

Intraocular pressure response to inversion.

Intraocular pressure (IOP) response to hanging completely head-down (inversion) was measured in 26 healthy young subjects. Systolic and diastolic blood pressure (BP) were also recorded. From the standing position, subjects were rotated 180 degrees and suspended by the ankles from a gravity inversion device. IOP and BP were measured in the standing position, immediately upon inverting, 3 min after inverting, immediately on return to the standing position and 3 min later. Subjects remained at rest during the test. Mean standing right eye IOP of 16.4 mm Hg and left eye IOP of 15.9 mm Hg increased to 34 and 31 mm Hg, respectively. Mean standing BP of 110/77 mm Hg increased to 130/90 mm Hg. Both IOP and BP remained elevated during inversion and decreased to near original values on return to the standing position. IOP significantly increases when the posture changes from standing to hanging completely head-down.

Adult↗
PubMed1977

Nonpuerperal inversion of the uterus by endometrial stromal sarcoma of the uterine fundus.

Nonpuerperal inversion of the uterus is rare; the 69th such case in the English literature is reported. Although caused most frequently by submucous leiomyoma, nonpuerperal uterine inversion may be caused by carcinoma or, as in this report, a sarcoma of the uterine fundus. For optimal therapy and to reduce surgical complications, the correct preoperative diagnosis of uterine inversion and any concomitant disease is mandatory.

Aged↗
PubMed2002

Inverse laminoplasty for the treatment of lumbar spinal stenosis.

STUDY DESIGN: Fifteen patients with lumbar spinal stenosis were treated by a new technique, inverse laminoplasty, and the results were evaluated clinically and radiologically. OBJECTIVE: To present the advantages of inverse laminoplasty over laminectomy for the treatment of lumbar spinal stenosis. SUMMARY AND BACKGROUND DATA: Laminectomy has been used widely in the treatment of lumbar spinal stenosis. Destruction of the spinal bony structure, instability, and peridural scar formation are the main problems with this procedure. To overcome these disadvantages, a practical technique is presented here. MATERIAL AND METHODS: In a prospective study, 15 patients who underwent surgery with the inverse laminoplasty technique were evaluated clinically and radiologically. The Oswestry Disability Index was used for clinical assessment. L4-L5 spinal stenosis was detected in all patients. As the operative technique, the L4 lamina was elevated en bloc using a high-speed drill and rongeur. After removal of the ligamentum flavum, the roof of the foramina, and/or disc, the lamina was rotated 180 degrees, rested on facets, and reattached by use of a titanium miniplate. RESULTS: All patients improved clinically and neurologically after this procedure. The mean Oswestry Disability Score was 38.33 preoperatively and 7.0 postoperatively. The mean follow-up time was 17.3 months. Spinal canal diameters were calculated by preoperative and postoperative computed tomography, and the mean enlargement was 77.8%. No complications were observed. CONCLUSION: With this technique, the important integrity of the spinal osseous structures is preserved, and a significant enlargement of the spinal canal area is achieved. This technique prevents peridural scar formation after laminectomy caused by a mechanical barrier effect. Long-term follow-up is needed to evaluate spinal stability in these patients.

Adolescent↗
PubMed2003

Inverse relation between osteoporosis and spondylosis in postmenopausal women as evaluated by bone mineral density and semiquantitative scoring of spinal degeneration.

STUDY DESIGN: The relation between bone mineral density and severity of spondylosis was evaluated in postmenopausal women. OBJECTIVE: To examine the possible inverse relation between osteoporosis and spondylosis by evaluating the association between bone mineral density and osteophyte formation or intervertebral disc narrowing using a semiquantitative scoring system. SUMMARY OF BACKGROUND DATA: The literature contains studies demonstrating an inverse relation between osteoporosis and spondylosis as well as those documenting insufficient support for such a relation. However, in these studies, only limited-range grading systems (e.g., Grades 1-4) were used to evaluate the severity of spondylosis. METHODS: In this study, 104 postmenopausal women older than 60 years underwent bone mineral density measurement of the lumbar spine (anteroposterior, lateral, and midlateral) and proximal femur (femoral neck, trochanter, and Ward's triangle) using dual-energy x-ray absorptiometry. Raw data representing the semiquantitative osteophyte score and disc score as well as the number of vertebral fractures were obtained using spinal radiograph. Correlations between bone mineral density and the radiographic variable were then analyzed. RESULTS: Significant negative correlations were found between all bone mineral density data and the number of vertebral fractures (-0.524 < or r= r < or = -0.347; P < 0.05). Marginal/moderate positive correlations were observed between the osteophyte score and the bone mineral density data (0.263 < or = r < or = 0.580, P < 0.05), and between the disc score and the bone mineral density data (0.233 < or = r < or = 0.570, P < 0.05).CONCLUSIONS On the basis of the finding that spondylotic changes in postmenopausal women exhibit positive correlations not only with the lumbar bone mineral density, but also with the remote-site bone mineral density, this study supports the view that osteoporosis has an inverse relation with spondylosis.

Aged↗
PubMed2006

Inverse-orthostasis may induce elevation of blood pressure due to sympathetic activation.

Microgravity and simulated microgravity may cause cardiovascular deconditioning, but mechanisms of instantaneous responses to inverse-orthostasis are not studied. Hence, we investigated transient and steady state cardiovascular changes by combining the tilt technique with cardiovascular telemetry. Normotensive and NO-deprived hypertensive Wistar rats were used to analyze responses of mean arterial blood pressure, heart rate, contractility, spontaneous baroreflex sensitivity (sBRS), and autonomic balance. Inverse-orthostasis tests were carried out by 45 degrees head-down tilting (repeated 3 x 5 mins "R", or sustained for 120 mins "S"). In normotensive rats, horizontal control blood pressure was R111.3 +/- 1.7/S110.4 +/- 2.3 mm Hg and heart rate was R385.2 +/- 5.9/S371.1 +/- 6.1 BPM. Head-down tilt induced an increase in blood pressure by R5.9/S10.6 mm Hg, while heart rate, contractility, sBRS, and autonomic balance did not change. The hypertensive response was sustained, could be prevented by prazosin (10 mg/kgbw), and augmented by subanesthetic doses of chloralose (26 and 43 mg/kgbw). In NO-suppressed hypertension, control blood pressure and heart rate were R132.4 +/- 2.9/S130.0 +/- 4.1 mm Hg and R339.2 +/- 7.9/S307.2 +/- 23.6 BPM, respectively. Head-down tilt further increased blood pressure by R5.1/S10.5 mm Hg. These data demonstrate that conscious rats respond to inverse-orthostasis by sustained elevation of blood pressure independent of NO synthesis. This response is neither due to increased contractility and altered sBRS, nor due to non-specific stress, but probably due to sympathetic activation elicited by gravity-related reflexes, which increase peripheral resistance.

Anesthetics, Intravenous↗
PubMed2006

Phase-sensitive inversion recovery (PSIR) single-shot TrueFISP for assessment of myocardial infarction at 3 tesla.

PURPOSE: The aim of the current study was to show if contrast-to-noise ratio (CNR) could be improved without loss of diagnostic accuracy if a phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence is used at 3.0 T instead of 1.5 T. MATERIAL AND METHODS: Ten patients with myocardial infarction were examined on a 1.5 T magnetic resonance (MR) system (Avanto, Siemens Medical Systems) and at a 3.0 T MR system. Imaging delayed contrast enhancement was started 10 minutes after application of contrast material. A phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence was used at 1.5 and 3.0 T and compared with a segmented IR turboFLASH sequence at 1.5 T, which served as the reference method. Infarct volumes and CNR of infarction and normal myocardium were compared with the reference method. RESULTS: The PSIR Single-Shot TrueFISP technique allows for imaging nine slices during a single breathhold without adaptation of the inversion time. The mean value of CNR between infarction and normal myocardium was 5.9 at 1.5 T and 12.2 at 3.0 T (magnitude images). The CNR mean value of the reference method was 8.4. The CNR mean value at 3.0 T was significantly (P = 0.03) higher than the mean value of the reference method. The correlation coefficients of the infarct volumes, determined with the PSIR single-shot TrueFISP technique at 1.5 T and at 3.0 T and compared with the reference method, were r = 0.96 (P = 0.001) and r = 0.99 (P = 0.0001). CONCLUSION: The use of PSIR single-shot TrueFISP at 3.0 T allows for accurate detection and assessment of myocardial infarction. CNR is significantly higher at 3.0 T compared with 1.5 T. The PSIR single-shot technique at 3.0 T provides a higher CNR than the segmented reference technique at 1.5 T.

Adult↗
PubMed2003

Inverse and forward dynamics: models of multi-body systems.

Connected multi-body systems exhibit notoriously complex behaviour when driven by external and internal forces and torques. The problem of reconstructing the internal forces and/or torques from the movements and known external forces is called the 'inverse dynamics problem', whereas calculating motion from known internal forces and/or torques and resulting reaction forces is called the 'forward dynamics problem'. When stepping forward to cross the street, people use muscle forces that generate angular accelerations of their body segments and, by virtue of reaction forces from the street, a forward acceleration of the centre of mass of their body. Inverse dynamics calculations applied to a set of motion data from such an event can teach us how temporal patterns of joint torques were responsible for the observed motion. In forward dynamics calculations we may attempt to create motion from such temporal patterns, which is extremely difficult, because of the complex mechanical linkage along the chains forming the multi-body system. To understand, predict and sometimes control multi-body systems, we may want to have mathematical expressions for them. The Newton-Euler, Lagrangian and Featherstone approaches have their advantages and disadvantages. The simulation of collisions and the inclusion of muscle forces or other internal forces are discussed. Also, the possibility to perform a mixed inverse and forward dynamics calculation are dealt with. The use and limitations of these approaches form the conclusion.

Acceleration↗
PubMed1983

Inversion of the two segments of the herpes simplex virus genome in intertypic recombinants.

We have analysed by restriction site mapping the structures of the termini and L-S joint in several HSV-1/HSV-2 intertypic recombinants, including Bx1(28-1), the virion DNA of which has a marked overabundance of one orientation of the L segment, and subclones of Bx1(28-1). All recombinants with both orientations of L present in equal amounts contain TRL and IRL regions derived at least in part from the same parent (HSV-1 or HSV-2) as a result of previously undetected crossovers in these regions. Recombinants with a predominance of one orientation of L have TRL and IRL regions derived from different parents. Homology between a sequences alone at the L terminus and L-S joint is sufficient for normal inversion of L. Analysis of another recombinant, RE4, which fails to invert normally in both L and S, suggests that normal inversion of S is dependent upon the presence of TRS and IRS regions derived at least in part from the same parent. We conclude that segment inversion specifically depends upon the a sequence, that the process of DNA replication and maturation does not necessarily produce molecules with identical a sequences, and that direct ligation of termini may occur during DNA replication.

Base Sequence↗
PubMed2000

Molecular theory of helical sense inversions in chiral nematic liquid crystals

A molecular theory of the helical twisting in chiral liquid crystals is developed, which provides an explanation for the experimentally observed helical sense inversion induced by a change of concentration in binary mixtures of chiral and nonchiral nematic liquid crystals. The theory also describes the sense inversion induced by a change of temperature observed in some single component nematics. The theory present is based on a simple model of a chiral rigid molecule, composed of several equivalent nonchiral sites, which are arranged in the molecule to form a chiral configuration. The macroscopic helical pitch in the chiral nematic phase, twist elastic constant, and nematic order parameters are calculated using the same molecular model. It is shown that the helical sense inversion can be determined by a large biaxiality of chiral molecules. It is also demonstrated that the biaxiality is important in determining the variation of the helical pitch with temperature and concentration.

Journal Article↗
PubMed2001

Optical generation of inversion walls in nematic liquid crystals.

An approach to generate inversion walls in nematic liquid crystals using optical reorientation is described. Planar cells with small pretilt are exposed to an oblique laser beam, which reverses the director tilt angle within the irradiated area. During the electric Freedericksz transition an inversion wall surrounding the laser spot is formed. A theoretical relation is provided for the critical laser intensity necessary to produce an inversion wall. Experimental results in a dye-doped nematic are in satisfactory agreement with the theory.

Journal Article↗
PubMed2002

Experimental study of population inversion between excited states of Ar I in a recombining Ar plasma by He contact cooling.

An experiment of He gas contact for generating population inversion in a recombining Ar plasma jet is carried out. Population inversion between Ar I excited states 5s'-->4p'[1/2](1) and 5s'-->4p[3/2](1,2), [5/2](2,3) is created by helium gas-contact cooling of electrons, whereas it is not created without gas contact. Ar I lines 1.14, 1.34, and 1.09 microm are strongly enhanced due to the He gas cooling. It is experimentally found that helium gas contact effectively lowers the electron temperature of the Ar plasma jet. The mechanisms giving rise to population inversion are discussed in terms of atomic collisional processes of the recombining plasma. The experimental results of electron temperature and population densities are discussed by a simple numerical analysis that we previously developed. It is shown that the experimental results are well explained by our modeling quantitatively for the case without gas contact, except that the agreement of number densities of lower lying nonlocal-thermodynamic-equilibrium levels is qualitative for the case with the gas contact.

Journal Article↗