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PubMed1985

Subjective effects of combined-axis vibration: II. Comparison of X-axis and X-plus-pitch vibrations.

Seated subjects matched their perceptions of the intensity of single-axis vibrations in the X axis, or combined-axis vibrations made up of X-axis and pitch motions, by adjusting the intensity of a sinusoidal, 5 Hz, Z-axis response vibration. Stimulus vibrations were sinusoidal at 3.15, 4, 5, 6.3 and 8 Hz. For each frequency, both types of vibration were presented at three acceleration levels related to three axis-to-seat distances for the pitch vibrations. Results showed that Z-axis response accelerations were essentially constant across frequency. However, matching responses were significantly higher for X-plus-pitch than for X-axis vibrations. These findings are in contrast to those of a previous experiment involving Y-axis and roll vibrations, and are probably due to additional input from the seat back for X and pitch motions. The two experiments do agree on the importance of the distance of the subject from the axis of rotation for angular motions. In both experiments, as stimulus acceleration (axis-to-seat distance) increased, response acceleration increased substantially at every frequency.

Acceleration↗
PubMed1988

Intensity judgments of vibrations in the X axis, Z axis, and X-plus-Z axes.

Seated subjects matched their perceptions of the intensity of X-axis, Z-axis, or X-plus-Z vibrations, by adjusting the intensity of a sinusoidal, 5 Hz, Y-axis response vibration. Stimuli were sinusoidal at 3.2, 5, and 8 Hz. For each frequency there were six vibration conditions (X axis alone, Z axis alone, or both axes together with 0 degree, 90 degrees, 180 degrees, or 270 degrees phase angles between them) each presented at each of two acceleration levels (0.15 and 0.25 G.R.M.S.). Results showed that Y-axis response accelerations for the dual-axis stimuli were greater than those for either one of their X-axis or Z-axis components. This occurred for both acceleration levels and for all three frequencies. However, the pattern of results indicated that response acceleration varied significantly as a function of the combination of phase angle and frequency. This is in contrast to results from a previous experiment, involving Y-plus-Z axis stimuli, which showed that the effects of phase angle were minimal at all three frequencies. Apparently phase angle, in combination with frequency, plays a significant role for X-plus-Z vibrations, but not for Y-plus-Z vibrations.

Acceleration↗
PubMed1984

Subjective effects of combined-axis vibration: comparison of Y-axis and Y-plus-roll vibrations.

A psychophysical matching experiment was conducted to compare the perceived intensity of Y-axis and Y-plus-roll vibrations. Seated subjects matched their perceptions of the intensity of single-axis stimulus vibrations in the Y-axis, or combined-axis stimulus vibrations made up of Y-axis and roll motions, by adjusting the intensity of a sinusoidal, 5 Hz, Z-axis response vibration. Stimulus vibrations were sinusoidal at 3.15, 4, 5, 6.3, and 8 Hz. For each frequency, both types of stimulus vibrations were presented at three acceleration levels related to three axis-to-seat distances for the roll vibrations. The results showed that as frequency increased the acceleration of the Z-axis matching response decreased for both types of stimuli. In addition, as stimulus acceleration (axis-to-seat distance) increased, response acceleration showed substantial increases at every frequency. However, the matching responses showed only minor differences due to vibration type, indicating that the effects of roll vibrations can be accounted for in terms of the Y-axis translational vibrations produced at the subject's seat.

Acceleration↗
PubMed2001

The effects of combined x-axis translations and y-axis rotations on projected lamina junction offset.

OBJECTIVES: To quantify the projection errors caused by the combining of selected x-axis translations with selected y-axis rotations as seen on plain film anteroposterior (AP) radiographs. STUDY DESIGN: A computer was used to model the projection of the lamina junction and points on the lateral body margins of a 2-dimensional vertebral model onto an AP radiograph. This simulation was done in the neutral position and in a number of combinations of x-axis translations and y-axis rotations. RESULTS: Some combinations of x-axis translation and y-axis rotation can increase or decrease the projected horizontal lamina offset as compared with what would be found with rotation alone. The projection of some combinations may lead the viewer to believe that rotation of the vertebral model is in the opposite direction of its true rotation. CONCLUSION: The projections of combined movements of x-axis translations and y-axis rotations can lead to confusion when the clinician attempts to discern quantity and direction of y-axis vertebral rotation from the AP radiograph.

Computer Graphics↗
PubMed1997

Axis II psychopathology as a function of Axis I disorders in childhood and adolescence.

OBJECTIVE: To examine the occurrence of elevated personality disorder (PD) dimensional scores in a community sample of young adults as a function of the occurrence of Axis I disorders through age 18 years. METHOD: 299 individuals who had been interviewed regarding Axis I disorders twice while in adolescence (first when 14 through 18 years of age) were carefully assessed regarding Axis I and II psychopathology at age 24. RESULTS: The prevalence of PD diagnoses was relatively low (3.8% in participants with a history of Axis I versus 1.7% in participants with no Axis I history). The occurrence of all four Axis I diagnostic categories (major depression, anxiety disorders, disruptive behavior disorders, substance use disorders) in childhood and adolescence was associated with elevated PD dimensional scores. The likelihood of elevated PD dimensional scores increased as a function of the number of Axis I disorders. Elevated PD scores were significantly associated with a negative course of major depression. CONCLUSIONS: Although the rates of PDs were low, the findings suggest a substantial degree of association between early-onset Axis I disorders and Axis II psychopathology in young adulthood. More research is needed to develop assessment and treatment recommendations addressing the early manifestations of PDs.

Adolescent↗
PubMed2005

On the interactions of the hypothalamic-pituitary-adrenal (HPA) axis and sleep: normal HPA axis activity and circadian rhythm, exemplary sleep disorders.

The hypothalamic-pituitary-adrenal (HPA) axis plays important roles in maintaining alertness and modulating sleep. Dysfunction of this axis at any level (CRH receptor, glucocorticoid receptor, or mineralocorticoid receptor) can disrupt sleep. Herein, we review normal sleep, normal HPA axis physiology and circadian rhythm, the effects of the HPA axis on sleep, as well as the effects of sleep on the HPA axis. We also discuss the potential role of CRH in circadian-dependent alerting, aside from its role in the stress response. Two clinically relevant sleep disorders with likely HPA axis dysfunction, insomnia and obstructive sleep apnea, are discussed. In insomnia, we discuss how HPA axis hyperactivity may be partially causal to the clinical syndrome. In obstructive sleep apnea, we discuss how HPA axis hyperactivity may be a consequence of the disorder and contribute to secondary pathology such as insulin resistance, hypertension, depression, and insomnia. Mechanisms by which cortisol can affect slow wave sleep are discussed, as is the role the HPA axis plays in secondary effects of primary sleep disorders.

Circadian Rhythm↗
PubMed2000

Axis I and Axis II disorders in alcoholics and drug addicts: fact or artifact?

OBJECTIVE: It has been argued that Axis I and Axis II disorders diagnosed in substance users refer to substance-induced conditions rather than to independent psychiatric conditions; this argument will be referred to as the substance-related artifact hypothesis. Furthermore, Axis II symptoms co-occurring with Axis I disorders have been attributed to the contamination of personality assessment by mood and/or anxiety state effects (the trait-state artifact hypothesis). The present study is the first to prospectively examine the validity of these two hypothesized "artifacts" in substance users. METHOD: In 276 individuals (57.6% female) applying for substance use treatment, current substance use disorders, mood/anxiety disorders and Axis II disorders were diagnosed using semistructured interviews both at baseline and at 1-year follow-up. The substance-related artifact hypothesis is tested by examining the covariation between recovery from substance use disorders on the one hand and recovery from and/or improvement of mood/anxiety and Axis II disorders on the other hand. The trait-state artifact hypothesis is tested by examining the covariation between recovery from mood/anxiety disorders on the one hand and recovery from and/or improvement of Axis II disorders on the other hand. RESULTS: Recovery from substance use disorders covaried with recovery from and improvement of mood/anxiety disorders, but not with recovery from or improvement of Axis II pathology. Furthermore, recovery from mood/anxiety disorders covaried with recovery from and improvement of personality disorders, in particular Cluster C disorders. CONCLUSIONS: Results from this study suggest that mood/anxiety disorders, but not personality disorders, diagnosed among people with substance use disorder may partly reflect substance-related artifacts. Furthermore, this study provides evidence for the contention that semistructured interview assessment of Axis II, at least without inquiry on an item-by-item basis, is susceptible to contamination by mood/anxiety state effects.

Adult↗
PubMed2005

The functional flexion-extension axis of the knee corresponds to the surgical epicondylar axis: in vivo analysis using a biplanar image-matching technique.

We investigated the concept that the knee has a fixed flexion-extension axis in the posterior femoral condyles and that this functional axis corresponds to the surgical epicondylar axis in vivo. We used a biplanar image-matching technique to perform the in vivo analysis of 9 normal knees to determine the location of the functional flexion-extension axis of the knee using an optimization technique. The functional flexion-extension axis passed through the sulcus of the medial epicondyle and the prominence of the lateral epicondyle. Flexion and extension of the knee could be represented as a rotation around a fixed axis, and this functional axis corresponded to the surgical epicondylar axis during a 0 degrees to 90 degrees flexion. This study assists more understanding of knee kinematics and provides useful information for the design and positioning of the prostheses used in total knee arthroplasty.

Adult↗
PubMed1999

Axis I and axis II comorbidity in panic/agoraphobic patients with and without suicidal ideation.

In view of the controversial relationship between certain aspects of panic disorder with agoraphobia (PDA), suicidal ideation and comorbidity, the purposes of this study were to compare severity of PDA and Axis I and Axis II comorbidity in PDA patients with and without suicidal ideation, and to examine predictors of suicidal ideation in these patients. Eighty-eight consecutive outpatients with PDA were administered structured diagnostic interviews for the DSM-IV Axis I and Axis II disorders (SCID-I and SCID-II), while the severity of PDA was assessed by means of the Panic Disorder Severity Scale. Of the patients, 25 (28.4%) reported suicidal ideation in past years ('ideators'). The severity of PDA was greater among ideators, and they were significantly more likely to have a personality disorder and more than one comorbid Axis I and Axis II disorder. There were no ideators without either Axis I or Axis II comorbidity. Univariate logistic regression identified several predictors of suicidal ideation: any DSM-IV Cluster C personality disorder, any DSM-IV Cluster B personality disorder, any comorbid mood disorder, and severity of PDA. With multivariate logistic regression, a combination of any Cluster C personality disorder and severity of PDA emerged as the most significant predictor of suicidal ideation. These findings have implications for clinical practice in that PDA patients should be carefully assessed for the severity of their illness and presence of certain personality disorders and comorbid mood disorders, because they may all increase the risk for suicidal ideation.

Adult↗
PubMedDate not supplied

Correlation and quantification of relative 2-dimensional projected vertebral endplate z-axis rotations with 3-dimensional y-axis vertebral rotations and focal spot elevations.

BACKGROUND: The use of lines erected on the vertebral endplates of the anterior-to-posterior radiograph to assess z-axis vertebral rotation is a common clinical practice. OBJECTIVE: To quantify the projection/distortion error of lateral flexion (z-axis rotation) measurement, which results from actual axial (y-axis) rotation and changes in focal spot elevation, on AP radiographs. STUDY DESIGN: A 3-dimensional model of a 4th and 5th lumbar vertebrae was constructed with a computer. The angle between the projected inferior vertebral endplate of the 4th lumbar vertebra, and the projected superior vertebral endplate of the 5th lumbar vertebra was measured. This was done for combinations of 0, 7, 14, and 21 degrees of axial (-y-axis) rotation with 0, 15, and 30 cm of elevation of a modeled focal spot. RESULTS: An angle was produced between the projected inferior 4th lumbar vertebral endplate and the projected superior 5th lumbar vertebral endplate as a result of y-axis rotation of the 3-dimensional model. Increasing magnitudes of y-axis rotation and increasing focal spot elevation produced a lack of confidence in this measurement. CONCLUSION: In a clinical setting, limited ranges of y-axis rotation have little significant effect on the accuracy of this measurement. Increases in y-axis rotation and focal spot elevation can affect measurement accuracy.

Computer-Aided Design↗
PubMedDate not supplied

Comparability of left ventricular M-mode echocardiography in dogs performed in long-axis and short-axis.

The purpose of this prospective study was to determine comparability of left ventricular (LV) M-mode echocardiographic indices derived from right parasternal long-axis and short-axis imaging planes. In 104 dogs (37 healthy dogs and 67 dogs with heart disease), LV M-mode echocardiograms were recorded from both long-axis and short-axis views and interventricular septum thickness (IVS), left ventricular internal dimensions (LVD), left ventricular posterior wall thickness (LVPW), and LV shortening fraction (FS) were measured. Statistical analysis included paired t-test and graphical analysis to assess agreement between the two methods of data acquisition. Mean LVD in systole and diastole and mean IVS in systole were significantly (P<0.001) larger when measured from short-axis recordings compared to long-axis measurements. An increased magnitude of measurement resulted in increased differences between the methods for LV dimensions and fractional shortening. Differences between the two methods were small and within clinically acceptable limits in normal dogs. However, in 23 (34%) of the dogs with cardiac abnormality, one or more LV M-mode derived dimension obtained from one imaging plane did not agree sufficiently closely with the same measure from the other plane. Only for measurement of FS was there good agreement between methods in dogs with cardiac disease. Therefore, with the exception of FS, data gained from LV short-axis and long-axis M-mode recordings should not be used interchangeably in dogs with cardiac disease.

Animals↗
PubMed2002

Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex.

The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head movements.

Adaptation, Physiological↗
PubMed2004

Pilot study evaluating the effects of a cervical headgear on the C-axis: the growth axis of the dentomaxillary complex.

The C-axis, a growth vector for the dentomaxillary complex, is a means of quantifying complex maxillary growth in the sagittal plane through 3 key cephalometric measurements. This pilot study examined the effect of a cervical headgear, worn 8 to 10 hours per day, on the growth axis. The mean velocity of C-axis length increase in normally growing boys in the age range studied is 1.14 mm per year. In normally growing girls, the C-axis length increase is nonlinear, varying from a mean of 1.67 mm per year at age 9 and to 0.78 mm per year at 13.5 years of age. The cervical headgear reduced the C-axis length increases by 73.7% in boys and 61.1% in girls. The growth axis vector angle theta; was not clinically affected in either sex, but the palatal plane angle alpha became more acute in both sexes, rather than becoming more obtuse as it does in normally growing adolescents. Additional research should be undertaken to determine the effects on the C-axis by other cervical headgears having different lines of action relative to the center of resistance of the dentomaxillary complex, as well as occipital-pull and straight distal-pull headgear.

Adolescent↗
PubMedDate not supplied

[Serotoninergic system and limbic-hypothalamic-pituitary-adrenal axis (LHPA axis) in depression].

Depression is associated with the dysfunction in the serotoninergic (5-HT, 5-hydroxytryptamine) transmission and dysregulation of the limbic-hypothalamic-pituitary-adrenal axis (LHPA axis). In depression, the 5-HT system exhibits impaired presynaptic activity of 5-HT neurones, an increased activity of central postsynaptic 5-HT2A receptors, decreased activity of postsynaptic 5-HT1A receptors and altered synaptic 5-HT uptake. The coexistent dysregulation of the LHPA axis is predominantly linked to GR (glucocorticoid receptor) dysfunction within the limbic system along with hypercortisolemia, MR (mineralocorticoid receptor) and GR receptors imbalance which results in impaired negative feedback mechanisms in the LHPA axis loops. Several clinical and animal studies revealed the involvement of 5-HT1A system in LHPA axis regulatory mechanisms. That association seems to be dependent on the corticoid levels. The impaired GR receptor function and MR/GR receptors imbalance alter the negative feedback regulation within the LHPA axis which is followed by its dysregulation and hypercortisolemia that is further associated with the decreased activity of postsynaptic 5-HT1A receptors resulting in a serotoninergic dysfunction. The aim of this paper is to discuss and review the current data on the existence of the hypothetical relationship between the activity of the serotoninergic system, predominantly 5-HT1A receptors, and LHPA axis in depression.

Antidepressive Agents↗
PubMed2001

Oral-aboral axis specification in the sea urchin embryo. I. Axis entrainment by respiratory asymmetry.

In embryos of indirectly developing echinoids, the secondary (oral-aboral) larval axis is established after fertilization by an as yet undiscovered process. One of the earliest manifestations of this axis is an asymmetry in mitochondrial respiration, with the prospective oral side of the embryo exhibiting a higher rate of respiration than the prospective aboral side. We show here that respiratory asymmetry can be experimentally induced within embryos by immobilizing them in tight clusters of four ("rosettes"). Within such clusters a redox gradient is established from the inside to the outside of the rosette. Vital staining of clustered embryos demonstrates that the side of the embryo facing the outside of the rosette (i.e., the most oxidizing) tends to become the oral side, while the side facing the inside tends to become the aboral side. Effective entrainment of the oral-aboral axis requires that the embryos remain immobilized in rosettes until the hatching blastula stage. To begin to investigate the molecular mechanisms underlying this effect we made use of P3A2, a transcriptional regulatory protein whose activity is spatially modulated along the oral-aboral axis. When synthetic mRNA encoding P3A2 fused to the VP16 activation domain is injected into eggs, it activates embryonic expression of a green fluorescent protein reporter gene containing a basal promoter and a single strong P3A2 target site. In embryo rosettes, such activation occurs predominantly on the outside of the rosette, suggesting that the activity of the P3A2 protein is spatially regulated by the respiratory asymmetry established by clustering the embryos. These findings are discussed with reference to earlier work on both oral-aboral axis specification and P3A2 and used to develop a testable model of the mechanism of oral-aboral axis specification in the sea urchin embryo.

Animals↗
PubMed2006

Does maternal psychopathology discriminate between children with DSM-IV generalised anxiety disorder or oppositional defiant disorder? The predictive validity of maternal axis I and axis II psychopathology.

What dimensions of maternal psychopathology predict internalising or externalising disorder in children? We conducted a study of maternal axis I and axis II psychopathology in a group of children 8-12 years of age with Generalised Anxiety Disorder (GAD), Oppositional Defiant Disorder (ODD) and non-patient controls (NC). By using Multigroup Discriminant Analyses (MDA) on three groups of children (N = 85) and measures of axis I and axis II psychopathology of their mothers, we attempted to discriminate between these groups on a data driven basis. Two separate MDA were computed, one based on maternal axis I disorders, and one based on maternal axis II disorders. The results demonstrated that maternal symptomatic and personality psychopathology was differentially related to childhood anxiety or behavioural disorders. Mothers of children with ODD were characterised by more negative emotions and detached personality styles, whereas mothers of children with GAD seemed to be more somatic preoccupied, controlling and over-protective.

Anxiety Disorders↗