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At least 919 records · Page 51Linked to original sources
PubMed2003

Off-axis edge glare in pseudophakic dysphotopsia.

PURPOSE: To characterize peripheral light focusing of oblique off-axis light in the edge-glare phenomenon associated with pseudophakic dysphotopsia. SETTING: Department of Ophthalmology, Prince of Wales Hospital, The University of New South Wales, Sydney, Australia. METHODS: Nonsequential optical ray-tracing (OptiCAD) was performed on a model pseudophakic human eye with an intraocular lens (IOL). The acrylic IOL had an anterior radius of 14.23 mm, posterior radius of 25.00 mm, center thickness of 0.72 mm, diameter of 6.00 mm, and refractive index of 1.5597. Peripheral light focusing caused by off-axis light was calculated for light rays incident on the temporal cornea at angles between 0 degrees and 120 degrees to the sagittal plane. RESULTS: Light incident on the temporal cornea at oblique angles was able to strike the nasal portion of the IOL and the nasal retina. The focusing gain was 2.56 times the incident intensity. The critical incidence window at the temporal cornea was between 71 degrees and 89 degrees to the sagittal plane. The light-focusing effect created foci of light in the nasal edge region of the IOL. In the mid range of permissive angles, up to 3 secondary images were formed, some of which may be apparent only under scotopic conditions. CONCLUSION: Off-axis light incident at the temporal cornea formed intense foci in the nasal edge of the IOL. Multiple secondary images can be formed. These spots constitute glare sources and may be of sufficient intensity to disturb vision. These findings indicate that off-axis light may be an important contributor to some disability glare problems and that IOL edge design should be reevaluated to minimize dysphotopsia associated with peripheral focusing effects.

Computer Simulation↗
PubMedDate not supplied

Biplane transesophageal echocardiography: clinical applications of the long-axis plane.

Tomography of the heart and great vessels is limited during conventional transesophageal echocardiography by the inability to rotate the transducer at the end of the transesophageal echocardiographic endoscope. A biplane transesophageal echocardiographic probe has been developed recently with a second transducer capable of long-axis imaging that yields long-axis views in addition to the familiar short-axis views. We describe our experience with 37 patients with a variety of cardiovascular diseases. In 17 patients new diagnostic information was obtained, although management was not changed. Long-axis scanning was particularly useful in the assessment of diseases of the thoracic aorta, valvular morphology and regurgitation, and congenital heart disease. Important limitations of the biplane imaging system include reduced image quality and a continued inability to rotate the transducer to obtain any desired plane of imaging. Nonetheless, biplane imaging enhances the versatility of transesophageal echocardiography and improves three-dimensional conceptualization of cardiac disease.

Aortic Diseases↗
PubMed2001

Funnel plots for detecting bias in meta-analysis: guidelines on choice of axis.

Asymmetry in funnel plots may indicate publication bias in meta-analysis, but the shape of the plot in the absence of bias depends on the choice of axes. We evaluated standard error, precision (inverse of standard error), variance, inverse of variance, sample size and log sample size (vertical axis) and log odds ratio, log risk ratio and risk difference (horizontal axis). Standard error is likely to be the best choice for the vertical axis: the expected shape in the absence of bias corresponds to a symmetrical funnel, straight lines to indicate 95% confidence intervals can be included and the plot emphasises smaller studies which are more prone to bias. Precision or inverse of variance is useful when comparing meta-analyses of small trials with subsequent large trials. The use of sample size or log sample size is problematic because the expected shape of the plot in the absence of bias is unpredictable. We found similar evidence for asymmetry and between trial variation in a sample of 78 published meta-analyses whether odds ratios or risk ratios were used on the horizontal axis. Different conclusions were reached for risk differences and this was related to increased between-trial variation. We conclude that funnel plots of meta-analyses should generally use standard error as the measure of study size and ratio measures of treatment effect.

Data Interpretation, Statistical↗
PubMedDate not supplied

Transformation of a set of slices rotated on a common axis to a set of Z-slices: application to three-dimensional visualization of the in vivo human lens.

A technique that transforms a set of images acquired as a rotating frame about an axis (Z axis) into a set of images along the Z axis in presented. This technique is applied to the three-dimensional visualization of the in vivo human lens. A Scheimpfling slit camera acquired 60 optical images through the in vivo human lens. Between each image acquisition the plane containing the slit beam of light was sequentially rotated. This set of 60 images was transformed into a new stack of images on the Z axis. The transformed stack of Z images was visualized with volume rendering software.

Aged↗
PubMed1999

Differences between men and women as regards the effects of protein-energy malnutrition on the hypothalamic-pituitary-gonadal axis.

Although protein-energy malnutrition (PEM) affects 50% of hospitalized patients, its effects on the hypothalamic-pituitary-gonadal (HPG) axis have not been extensively investigated. To investigate the effects of PEM on the HPG axis in hospitalized patients, 62 inpatients ages 18-91 y (35 men and 27 women) had a nutritional and hormonal evaluation. Hormones were determined in blood samples obtained between 0700 and 1200 h. Patients were divided into two subgroups: those with body mass index (BMI) <18.5 kg/m2 (low body mass index [LBMI]; 16 men, 13 women) and those with BMI >20 kg/m2 (normal-high body mass index [NHBMI]; 19 men, 14 women). The nutritional parameters of LBMI patients were inferior to those of NHBMI patients. Total and free testosterone levels were subnormal, 31.4% and 17.2% respectively, in all men; free testosterone was subnormal in 31.25% of LBMI versus 5.3% of NHBMI male patients and total testosterone concentration was subnormal in 43.8% of LBMI versus 21.1% of NHBMI male patients. Luteinizing hormone (LH) level was higher in LBMI men than in NHBMI men, whereas the reverse was the case for women, for whom follicle-stimulating hormone (FSH) also was lower in the LBMI group than the NHBMI group. The HPG axis hormones which best discriminated between the LBMI and NHBMI groups were free testosterone for men and LH and FSH for women, which were all lower in the LBMI than in the NHBMI group. LH was correlated with BMI and midupper arm muscle circumference (AMC) (women positively and men negatively) but not with triceps skin-fold thickness (TSF). Total testosterone level was positively correlated with AMC and free testosterone with TSF. Hypogonadism is common among hospitalized patients with PEM. Men with PEM have low testosterone levels with normal or high gonadotropin levels, which suggests impairment of Leydig cell function. Women with PEM suffer hypogonadotropic hypogonadism. AMC correlates positively with total serum testosterone concentration in men and with LH levels in women, suggesting that satisfactory function of the HPG axis requires a functional (protein) reserve as well as an energy (fat) reserve.

Adult↗
PubMed2000

Left-right axis malformations in man and mouse.

The study of left-right axis malformations in man and mouse has greatly advanced understanding of the mechanisms regulating vertebrate left-right axis formation. Recently, the roles of the TGF-beta family, Sonic hedgehog and fibroblast growth factor signaling, homeobox genes, and cilia in left-right axis determination have been more clearly defined. The identification of genes and environmental factors affecting left-right axis formation has important implications for understanding human laterality defects.

Animals↗
PubMed2002

Fetal programming of the growth hormone-insulin-like growth factor axis.

Epidemiological studies have shown that small body size at birth and during infancy is associated with increased rates of chronic diseases in adulthood, including cardiovascular disease and osteoporosis. Fetal programming of the growth hormone-insulin-like growth factor (GH-IGF) axis has been proposed as a potential candidate mechanism to explain the link between low birth weight and adult disease. The IGFs and IGF-binding proteins are nutritionally regulated in the fetus and fetal growth retardation leads to abnormalities in the GH-IGF axis. There are also abnormalities in the GH-IGF axis in many of the adult diseases that are associated with low birth weight, including cardiovascular disease and osteoporosis. Finally, there are data from both animals and humans suggesting that programming of the GH-IGF axis might exist.

Adult↗
PubMed2001

Medial axis reformation: a new visualization method for CT angiography.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate a new method (medial axis reformation [MAR]) for visualizing three-dimensional vascular data at electron-beam computed tomographic (CT) angiography. MATERIALS AND METHODS: MAR was performed automatically with a personal computer-based workstation. After the region of interest was edited, voxels were divided into groups according to their path lengths. Centroids of groups were connected to form the medial axis. Then, the medial axis was refined with multiscale medial response. Bifurcations were also detected and refined. Finally, curved sections were generated through the branches and laid out onto a single image by using a splitting method. The authors performed MAR during electron-beam CT angiography of coronary arteries, common carotid arteries, and iliac arteries. RESULTS: MAR displayed curved sections of branched vessels on one image, cut through the axis of vessels to show the vessel diameter objectively, and allowed the viewing direction to be altered arbitrarily. CONCLUSION: Results of preliminary applications demonstrate that MAR is a valuable new visualization method for CT angiography.

Adult↗
PubMed2004

Effect of budesonide aqueous nasal spray on hypothalamic-pituitary-adrenal axis function in children with allergic rhinitis.

BACKGROUND: Intranasal corticosteroids are safe and effective for treating allergic rhinitis in adults. Since children may receive more systemic corticosteroid on a dose-per-weight basis than adults, the safety of corticosteroid therapy in pediatric patients is an important issue. OBJECTIVE: To determine the effects of treatment with budesonide aqueous nasal spray using the recommended once-daily dose for adults and children 6 years and older on hypothalamic-pituitary-adrenal (HPA) axis function in pediatric patients with allergic rhinitis. METHODS: In a 6-week, multicenter, double-blind, placebo-controlled study, 78 patients aged 2 to 5 years with allergic rhinitis were treated with budesonide aqueous nasal spray (64 microg/d) or placebo. Mean change in morning plasma cortisol levels from baseline to study end 0, 30, and 60 minutes after low-dose (10-microg) cosyntropin stimulation and mean change in the difference from 0 to 30 minutes and from 0 to 60 minutes after cosyntropin stimulation were used to evaluate HPA axis function. RESULTS: Mean change from baseline to study end in plasma cortisol levels 0, 30, and 60 minutes after cosyntropin stimulation and the difference from 0 to 30 minutes and from 0 to 60 minutes were not significantly different between the treatment and placebo groups (P > .05 for all). At the end of the study, 3 budesonide aqueous nasal spray and 6 placebo patients were classified as having subnormal HPA axis function. The safety and tolerability profile of budesonide aqueous nasal spray was comparable to that of placebo. CONCLUSIONS: Administration of budesonide aqueous nasal spray for 6 weeks was well tolerated and safe and had no measurable suppressive effects on HPA axis function in patients aged 2 to 5 years with allergic rhinitis.

Aerosols↗
PubMed2001

The hypothalamic-pituitary-interrenal axis and the control of food intake in teleost fish.

Although environmental, social and physical stressors have been shown to inhibit food intake and feeding behavior in fish, little is known about the mechanisms that mediate the appetite-suppressing effects of stress. Since the hypothalamic-pituitary-interrenal (HPI) axis is activated in response to most forms of stress in fish, components of this axis may be involved in mediating the food intake reductions elicited by stress. Recent investigations into the brain regulation of food intake in fish have identified several signals with orexigenic and anorexigenic properties. Among these appetite-regulating signals are related neuropeptides that can activate the HPI axis, namely corticotropin-releasing factor (CRF) and urotensin I (UI). Central injections of CRF or UI, or treatments that result in an increase in hypothalamic CRF and UI gene expression, can elicit dose-dependent decreases in food intake that can be reversed by pre-treatment with a CRF-receptor antagonist. Evidence also suggests that cortisol, the end product of HPI activation in most fishes (i.e. Osteichthyes), may be involved in the regulation of food intake. Overall, while elements of the HPI axis may mediate some of the appetite-suppressing effects of stress, it is undetermined how either CRF-related peptides, cortisol, or other elements of the stress response interact with the complex circuitry of the hypothalamic feeding center.

Animals↗
PubMed1994

Multiple reciprocal relationships between in vivo cellular immunity and hypothalamic-pituitary-adrenal axis in depression.

Major depression is reportedly characterized by increased activity of the hypothalamic-pituitary-adrenal (HPA) axis and by in vivo immune activation. The present study was carried out in order to investigate the relationships between HPA-axis activity and in vivo immune function in depression. Towards this end the following parameters were measured: 24 h urinary cortisol (UC) excretion; basal and post-dexamethasone (DST) plasma cortisol, beta-endorphin/beta-lipotropin (beta END/beta LPH) and dexamethasone concentrations; and leucocyte subsets (i.e. lymphocytes, neutrophils, monocytes, CD4+, CD4+CD45RA+, CD4+CD45RO+, CD8+, CD8+CD57+, CD8+CD57-, HLA-DR+, CD25+ T cells, HLA-DR+, CD19+, CD20+, and CD21+ B cells) both pre- and post-DST. Dexamethasone administration (1 mg orally) induced leucocytosis, lymphocytopaenia, monocytopaenia and neutrophilia. HPA-axis non-suppressors exhibited a relative resistance to the enhancing (e.g. neutrophils) or depressant (e.g. lymphocytes, CD4+ T cells) effects of dexamethasone. There were significant correlations between UC excretion and the number of percentage of lymphocytes, monocytes, CD4+CD45RA+ and CD8+CD57- T cells (negatively) and neutrophils (positively). It is concluded that multiple and complex intertwined relationships between HPA-axis hyperactivity and systemic immune stimulation participate in the pathophysiology or pathogenesis of major depression.

Adult↗
PubMed2001

Treatment resistant depression and axis I co-morbidity.

BACKGROUND: Treatment resistant depression (TRD) continues to present a formidable challenge to clinicians, accounts for over half of the annual costs associated with treatment for depression and causes great frustration to patients. Although there have been studies attempting to define TRD, little information is available as to the cause of TRD. One suggestion is that patients with TRD have a greater frequency of co-morbid psychiatric disorders, which explains their resistance to standard antidepressant treatments. The objective of this study was to compare the co-morbidity of Axis I disorders between a sample of TRD patients and a sample of non-TRD patients. METHODS: TRD and non-TRD patients, recruited from two separate antidepressant treatment studies, were assessed for Axis I co-morbidity using the SCID-P for the DSM-III-R. Patients for the two samples were then matched for baseline HAM-D-17 total score and gender. RESULTS: Results reveal that non-TRD patients had a higher rate of both lifetime and current generalized anxiety disorder co-morbidity than did the TRD patients. No other statistically significant differences in Axis I co-morbidity were found. CONCLUSIONS: These findings do not support the idea that current or lifetime Axis I co-morbidity is more common in TRD than non-TRD patients. In fact, the only statistical difference showed non-TRD patients with higher co-morbidity rates.

Adolescent↗
PubMed2001

Comparison of methyl rotation axis order parameters derived from model-free analyses of (2)H and (13)C longitudinal and transverse relaxation rates measured in the same protein sample.

Recombinant HIV-1 protease was obtained from bacteria grown on a 98% D(2)O medium containing 3-(13)C pyruvic acid as the sole source of (13)C and (1)H. The purified protein is highly deuterated at non-methyl carbons, but contains significant populations of (13)CHD(2) and (13)CH(2)D methyl isotopomers. This pattern of isotope labeling permitted measurements of (1)H and (13)C relaxation rates of (13)CHD(2) isotopomers and (2)H (D) relaxation rates of (13)CH(2)D isotopomers using a single sample. The order parameters S(axis)(2), which characterize the motions of the methyl rotation axes, were derived from model-free analyses of R(1) and R(2) data sets measured for (13)C and (2)H spins. Our primary goal was to compare the S(axis)(2) values derived from the two independent types of data sets to test our understanding of the relaxation mechanisms involved. However, S(axis)(2) values derived from the analyses depend strongly on the geometry of the methyl group, the sizes of the quadrupolar and dipolar couplings, and the effects of bond vibrations and librations on these couplings. Therefore uncertainties in these basic physical parameters complicate comparison of the order parameters. This problem was circumvented by using an experimental relationship, between the methyl quadrupolar, (13)C-(13)C and (13)C-(1)H dipolar couplings, derived from independent measurements of residual static couplings of weakly aligned proteins by Ottiger and Bax (J. Am. Chem. Soc. 1999, 121, 4690-4695) and Mittermaier and Kay (J. Am. Chem. Soc. 1999, 121, 10608-10613). This approach placed a tight experimental restraint on the values of the (2)H quadrupolar and (13)C-(1)H dipolar interactions and greatly facilitated the accurate comparison of the relative values of the order parameters. When applied to our data this approach yielded satisfactory agreement between the S(axis)(2) values derived from the (13)C and (2)H data sets.

Amino Acids↗
PubMed1998

Contribution of long axis motion of left ventricular outflow to calculation of left ventricular stroke volume.

Stroke volume can be calculated by using noninvasive Doppler techniques. The products of pulsed Doppler stroke distance of left ventricular outflow and left ventricular outflow area can often be used to calculate stroke volume. However, left ventricular outflow also moves longitudinally toward the apex of the ventricle during systole, so that zero velocity flow cannot be detected by the usual pulsed Doppler studies. We evaluated the contribution of these zero velocity flow to the noninvasive estimation of left ventricular stroke volume in 20 patients with left ventricular disease and in 20 age matched healthy controls. Left ventricular stroke distance was calculated by summing the Doppler stroke distance and the outflow long axis motion. The percentage of zero velocity flow for total stroke volume was calculated in each group. Cardiac output was also measured by thermo-dilution technique. The percentage of zero velocity flow for total noninvasive stroke volume in patients with left ventricular disease was 2.5 +/- 1.1 ml (4.0 +/- 1.5%), significantly lower than in normal subjects, 3.6 +/- 1.0 ml (5.5 +/- 1.5%) (p < 0.05). These long axis motions are significantly reduced, especially in left ventricular disease. Amplitudes of the left ventricular outflow long axis motion were correlated with Doppler stroke distance in all (r = 0.54, p < 0.01). In patients with myocardial infarction, stroke volume by thermo-dilution methods and calculated stroke volume showed good correlation both only by Doppler stroke distance (y = 1.044x + 0.547, r = 0.968) and by Doppler and long axis motion (y = 0.989x + 0.521, r = 0.974). Compared with stroke volume measured by thermodilution method, stroke volume calculated only by Doppler stroke distance was underestimated. We thus demonstrated the influence of zero velocity flow on left ventricular outflow both in patients with left ventricular disease and in normal subjects.

Adult↗
PubMed1999

Prevalence of axis II comorbidity in bipolar patients with and without alcohol use disorders.

OBJECTIVE: This study sought to determine the prevalence of comorbid personality disorder in euthymic bipolar I patients. METHOD: Sixty-one outpatients were assessed using the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID II) and/or the Personality Diagnostic Questionnaire-Revised (PDQ-R). RESULTS: Thirty-eight percent of bipolar patients met criteria for an Axis II diagnosis based on the SCID II. Bipolar subjects with a history of comorbid alcohol use disorder were significantly more likely to have a SCID II diagnosis (52%) compared to those bipolar subjects without an alcohol use disorder history (24%). Cluster A diagnoses were significantly more common in the bipolar/alcohol use disorder group. The PDQ-R consistently overdiagnosed Axis II disorders, finding 62% of the overall bipolar group to have an Axis II diagnosis. CONCLUSIONS: Euthymic bipolar patients may have an increased rate of personality disorders, but much less so than previously reported in studies that did not take into account (1) current mood state, (2) comorbidity for an alcohol use disorder, and (3) instrument used for assessment of Axis II psychopathology.

Adult↗
PubMed2002

Impact of axis II comorbidity on the course of bipolar illness in men: a retrospective chart review.

OBJECTIVES: The purpose of this study was to investigate whether the presence of comorbid personality disorder influences the course of bipolar illness. METHODS: Fifty-two euthymic male bipolar I out-patients were assessed using the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID II). Bipolar patients with an axis II diagnosis were compared with those without an axis II diagnosis on retrospectively obtained demographic, clinical and course of illness variables. RESULTS: Thirty-eight percent of the bipolar patients met criteria for an axis II diagnosis. Two (4%) met criteria for (only) a Cluster A disorder, four (8%) for (only) a Cluster B, and six (12%) for (only) a Cluster C disorder. One (2%) bipolar patient met criteria a disorder in both Clusters A and B, and one (2%) for a disorder in Clusters B and C. Five (10%) met criteria for at least one disorder in Clusters A and C, and one met criteria for disorders in Clusters A, B, and C. The presence of a personality disorder was significantly associated with a lower rate of current employment, a higher number of currently prescribed psychiatric medications, and a higher incidence of a history of both alcohol and substance use disorders compared with the bipolar patients without axis II pathology. CONCLUSIONS: Our results extend previous findings of an association between comorbid personality disorder in bipolar I patients and factors that suggest a more difficult course of bipolar illness.

Adult↗
PubMed1994

Relationship between the five-factor model of personality and Axis I disorders in a nonclinical sample.

The relationship between the five-factor model (FFM) of personality and Axis I disorders was evaluated in a nonclinical sample of 468 young adults. In general, scores on the 5 personality dimensions of neuroticism, extraversion, openness to experience, agreeableness, and conscientiousness (assessed via the NEO Five-Factor Inventory) distinguished subjects with and without a variety of Axis I diagnoses from the revised third edition of the Diagnostic and Statistical Manual of Mental Disorders. In several instances, results indicate that scores on these dimensions were differentially sensitive to diagnosis. Furthermore, scores on these 5 personality dimensions accounted for unique variance in several Axis I diagnoses above and beyond that accounted for by a general measure of current psychopathological symptoms. These results support the utility of the FFM of personality in Axis I diagnostic assessment.

Adult↗
PubMed1994

Cell interaction between compartments establishes the proximal-distal axis of Drosophila legs.

The appendage primordia of Drosophila are subdivided into compartments by the localized expression of transcription factors. Interaction between cells in adjacent compartments establishes organizing centres responsible for generating spatial pattern and promoting cell proliferation in the developing appendages. Localized expression of hedgehog (hh) in the posterior compartment of the leg imaginal disc directs expression of wingless (wg) in ventral-anterior cells and decapentaplegic (dpp) in dorsal-anterior cells near the anterior-posterior compartment boundary; wg then acts to specify ventral cell fate and to organize the dorsal-ventral axis of the leg. Interaction between wg-expressing ventral cells and dorsal cells near the anterior-posterior compartment boundary promotes axis formation in the leg. Here we show that the combined action of wg-expressing cells in the ventral-anterior compartment and dpp-expressing cells in the dorsal-anterior compartment activates expression of Distal-less, a gene required for proximal-distal axis formation in the limbs. These results demonstrate that sequential interaction between anterior-posterior and dorsal-ventral compartments establishes the proximal-distal axis of the limbs.

Animals↗