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PubMed1998

Measurement of off-axis and peripheral skin dose using radiochromic film.

A radiotheraphy skin dose profile can be obtained with radiochromic film. The central axis skin dose relative to Dmax for a 10 x 10 cm2 field size was found to be 22%, 17% and 15.5% for 6 MV, 10 MV and 18 MV photon beams. Peripheral dose increased with increasing field size. At 10 MV the skin dose 2 cm outside the geometric field edge was measured as 6%, 10% and 17% for 10 x 10 cm2, 20 x 20 cm2 and 30 x 30 cm2 field sizes respectively. Off-axis skin dose decreased as distance increased from central axis for fields with Perspex block trays. For a 20 x 20 cm2 field, an approximately 5-8% drop in percentage skin dose was observed from central axis to the beam edge.

Biophysical Phenomena↗

PubMed2004

The use of a principal axis model to examine individual plant harvest index in four grain legumes.

BACKGROUND AND AIMS: A principal axis model (PAM) has been proposed to enable the selection of crop ideotypes. The PAM enables plant-to-plant variability within crops to be quantified and compared. The aim of this paper is to validate the PAM for four grain legumes. METHODS: Four grain legumes (Cicer arietinum, Lens culinaris, Lupinus angustifolius, Pisum sativum) were used to quantify the influence of plant-to-plant variability on crop yields. To create variability, populations of 10, 100 and 400 plants m(-2) were established 'on-the-square' with sowing depths of 2, 5 and 10 cm. Further, a central plant was treated with nitrogen and the impact of this on its four neighbouring plants was examined. Seeds were sown and plants harvested individually by hand. KEY RESULTS: Mean individual plant seed weight (SWT) and plant weight (PWT) decreased as plant population increased but there was a consistent and strong (R2 > 0.90) linear relationship between SWT and PWT, with a negative SWT-axis intercept in all species. These components form the basis of the principal axis model (PAM). The PAM was used to summarize the performance of individual plants within a crop and quantify the variability caused by N treatment and the lowest and highest yielding individual plants. A negative SWT-axis intercept indicated that a minimum plant weight (MPW) was required for seed production and therefore the relationship between plant harvest index (PHI) and PWT was asymptotic. The heaviest MPW was calculated for plants grown at the lowest plant population and it was species-dependent, being higher in the larger seeded species. CONCLUSIONS: Agronomic or physiological characteristics that lead to variability in PWT within a population will decrease PHI, and crop yield. The PAM may be useful in breeding programmes to identify plant phenotypes that minimize this plant-to-plant variability.

Cicer↗

PubMed2000

Antenatal dexamethasone and the growth hormone-insulin-like growth factor axis.

Dexamethasone administration has marked effects on the growth hormone-insulin-like growth factor axis (GH-IGF) in animal and human studies. During pregnancy in the rat, it is associated with fetal growth restriction due to inhibition of IGF bioactivity. In the human only repeated dosages have been associated with fetal growth restriction. The aim of this study is to test the hypothesis that antenatal dexamethasone administration to pregnant women is associated with reduced activity of the GH-IGF axis. To achieve this blood samples were taken from 12 pregnant women pre- and at 24 h and 48 h after dexamethasone administration. In these samples GH, IGF-I, IGF bioactivity and IGF binding protein (IGFBP)-3 protease activity were measured. In view of the interaction between insulin and the GH-IGF axis, glucose and insulin concentrations were also measured. There were no significant differences between the concentrations of GH, IGF-I, IGF bioactivity and IGFBP-3 protease activity before and after dexamethasone. The concentrations of glucose and insulin were significantly higher at 24 h, but not 48 h post-dexamethasone. It is concluded that a single antenatal course of dexamethasone does not alter the GH-IGF-I axis in pregnant women at the time points studied.

Adult↗

PubMed2006

The axis of polarity of the mouse blastocyst is specified before blastulation and independently of the zona pellucida.

BACKGROUND: Rather than being prepatterned, orientation of the embryonic-abembryonic (Em-Ab) axis of the mouse blastocyst has been claimed to depend on the conceptus being constrained by its zona pellucida (ZP) during blastulation. This hypothesis merited closer scrutiny, because it seemed at variance with observations on living conceptuses. METHODS: Two-cell conceptuses with an oil drop injected into the lesser diameter (LD) of the ZP at the first cleavage plane were cultured until shortly before blastulation when the blastomere underlying the drop was labelled with carbocyanine dye. After removing the ZP, conceptuses were re-cultured to the blastocyst stage for recording the position along the axis of the centres of the patches of labelled cells. RESULTS: These centres showed significant bias towards the equatorial (Eq) region of the axis compared with those resulting from labelling a blastomere at random, even following softening of the ZP at the 2-cell stage. This was also true if conceptuses were denuded at the 2-cell stage and the blastomere underlying an intact second polar body (PB) labelled in morulae. CONCLUSIONS: These findings further support the view that the Em-Ab axis of the mouse blastocyst is normally prepatterned and provide no evidence of a role for the ZP in its specification.

Animals↗

PubMed2005

Dysregulation of the hypothalamic-pituitary-gonadal axis with menopause and andropause promotes neurodegenerative senescence.

Senescence is characterized neurologically by a decline in cognitive function, which we propose is the result of degenerative processes initiated by the dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis with menopause and andropause. Compelling epidemiologic evidence to support this assertion includes the increased prevalence of Alzheimer disease (AD) in women, the correlation of serum HPG hormones with disease and the decreased incidence, and delay in the onset of AD following hormone replacement therapy. Dysregulation of the axis at this time leads to alterations in the concentrations of all serum HPG hormones (decreased neuronal sex steroid signaling, but increased neuronal gonadotropin releasing hormone, luteinizing hormone, and activin signaling). Hormones of the HPG axis, receptors for which are present in the adult brain, are important regulators of cell proliferation and differentiation during growth and development. Based on this, we propose that dysregulated HPG hormone signaling with menopause/andropause leads to the abortive reentry of differentiated neurons into the cell cycle via a process we term "dyosis." Interestingly, the major biochemical and neuropathologic changes reported for the AD brain also are intimately associated with neuron division: altered AbetaPP metabolism, Abeta deposition, tau phosphorylation, mitochondrial alterations, chromosomal replication, synapse loss, and death of differentiated neurons. Recent evidence supports the premise that AD-related biochemical changes are likely the combined result of increased mitotic signaling by gonadotropins and GnRH, decreased differentiative and neuroprotective signaling via sex steroids, and increased differentiative signaling via activins. This results in a hormonal milieu that is permissive of cell cycle reentry but does not allow completion of metaphase. Partial resetting of the axis following administration of normal endogenous sex steroids delays the onset and decreases the incidence of AD. Ideally, supplementation with HPG hormones should mimic closely the serum concentrations of all HPG hormones in reproductive men and cycling women to prevent dyotic signaling and attempted neuron division.

Adult↗

PubMedDate not supplied

Narrow axis: an inherited anomaly of the second cervical vertebra in the rabbit.

Narrow axis, an inherited anomaly resulting in a marked narrowing of the second cervical vertebra, has been observed in strain X/J rabbits. This condition is first recognizable on X rays at 32-33 days gestation. For size comparisons 21 measurements of the first five cervical vertebrae were taken on the skeletons of each of 14 strain X/J animals (7 normal and 7 with narrow axis) and 14 IIIC/J animals for control at two months of age and 27 strain X/J (11 normal and 16 narrow axis) and 14 strain IIIC/J at seven months of age. The primary effect appeared to be a premature fusion of the centrum with its neural arches. Expression is variable. The effect on the posterior articulation of the atlas appeared to be secondary and adaptive. The other cervical vertebrae and the foramen magnum were relatively unaffected. In the 20-year period encompassed in this report, X rays of 3244 rabbits were used for genetic analysis. Inheritance appears to be due to a single autosomal recessive gene with incomplete penetrance. The condition is neither sex-linked nor sex-limited. We propose the symbol nx for the gene responsible for narrow axis in the rabbit.

Animals↗

PubMed1997

A conserved Hox axis in the mouse and human female reproductive system: late establishment and persistent adult expression of the Hoxa cluster genes.

The mammalian female reproductive system arises from the uniform paramesonephric duct. The molecular mechanisms that establish differential development along this axis are unknown. We determined the pattern and timing of genes of the Hoxa axis in the development of the Müllerian tract. Hoxa-9, Hoxa-10, Hoxa-11, and Hoxa-13 are all expressed along the length of the paramesonephric duct in the embryonic mouse. After birth, a spatial Hox axis is established, corresponding to the postnatal differentiation of this organ system in the mouse. Hoxa-9 is expressed in the fallopian tubes, Hoxa-10 in the uterus, Hoxa-11 in the uterus and uterine cervix, and Hoxa-13 in the upper vagina. This expression pattern follows the paradigm of spatial colinearity but is a novel exception to temporal colinearity that has been considered typical of Hox genes. These genes remain expressed in the adult mouse and are expressed in the same pattern in the human. The female reproductive system undergoes dramatic structural and functional changes during the estrous cycle and in pregnancy, retaining a high degree of developmental plasticity. The late establishment of a Hox axis and persistent expression of Hox genes in the adult may play an important role in preserving this plasticity.

Adult↗

PubMed2005

Human hair follicles display a functional equivalent of the hypothalamic-pituitary-adrenal axis and synthesize cortisol.

The skin and its major appendages are prominent target organs and potent sources of key players along the classical hypothalamic-pituitary axis, such as corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and alpha melanocyte stimulating hormone (alpha-MSH), and even express key steroidogenic enzymes. Therefore, it may have established local stress response systems that resemble the hypothalamic-pituitary-adrenal (HPA) axis. However, functional evidence that this is indeed the case in normal human skin in situ has still been missing. We show that microdissected, organ-cultured human scalp hair follicles respond to CRH stimulation by up-regulating proopiomelanocortin (POMC) transcription and immunoreactivity (IR) for ACTH and alpha-MSH, which must have been processed from POMC. CRH, alpha-MSH, and ACTH also modulate expression of their cognate receptors (CRH-R1, MC1-R, MC2-R). In addition, the strongest stimulus for adrenal cortisol production, ACTH, also up-regulates cortisol-IR in the hair follicles. Isolated human hair follicles secrete substantial levels of cortisol into the culture medium, and this activity is further up-regulated by CRH. CRH also modulates important functional hair growth parameters in vitro (hair shaft elongation, catagen induction, hair keratinocyte proliferation, melanin production). Finally, human hair follicles display HPA axis-like regulatory feedback systems, since the glucocorticoid receptor agonist hydrocortisone down-regulates follicular CRH expression. Thus, even in the absence of endocrine, neural, or vascular systemic connections, normal human scalp hair follicles directly respond to CRH stimulation in a strikingly similar manner to what is seen in the classical HPA axis, including synthesis and secretion of cortisol and activation of prototypic neuroendocrine feedback loops.

Adrenocorticotropic Hormone↗

PubMed1998

Axis I psychopathology in individuals with traumatic brain injury.

OBJECTIVES: To assess the incidence, comorbidity, and patterns of resolution of DSM-IV mood, anxiety, and substance use disorders in individuals with traumatic brain injury (TBI). DESIGN: The Structured Clinical Interview for DSM-IV Diagnoses (SCID) was utilized. Diagnoses were determined for three onset points relative to TBI onset: pre-TBI, post-TBI, and current diagnosis. Contrasts of prevalence rates with community-based samples, as well as chi-square analysis and analysis of variance were used. Demographics considered in analyses included gender, marital status, severity of injury, and years since TBI onset. SETTING: Urban, suburban, and rural New York state. PARTICIPANTS: 100 adults with TBI who were between the ages of 18 and 65 years and who were, on average, 8 years post onset at time of interview. MAIN OUTCOME MEASURES: SCID Axis I mood diagnoses of major depression, dysthymia, and bipolar disorder; anxiety diagnoses of panic disorder, obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), and phobia; and substance use disorders. RESULTS: Prior to TBI, a significant percentage of individuals presented with substance use disorders. After TBI, the most frequent Axis I diagnoses were major depression and select anxiety disorders (ie, PTSD, OCD, and panic disorder). Comorbidity was high, with 44% of individuals presenting with two or more Axis I diagnoses post TBI. Individuals without a pre-TBI Axis I disorder were more likely to develop post-TBI major depression and substance use disorders. Rates of resolution were similar for individuals regardless of previous psychiatric histories. Major depression and substance use disorders were more likely than were anxiety disorders to remit. CONCLUSION: TBI is a risk factor for subsequent psychiatric disabilities. The need for proactive psychiatric assessment and timely interventions in individuals post TBI is indicated.

Adult↗

PubMed2000

A computerized method for mathematical description of three-dimensional root canal axis.

Knowledge of the three-dimensional (3D) morphology of root canals is important for successful endodontic treatment. The objective of the present study was to determine the 3D root canal axis mathematically. Two views (mesiodistal and buccolingual) of digitized images were taken from extracted natural human teeth. Geometric reconstruction to standardize projection geometry was conducted on images. Because 90-degree turn-around image pairs are Monge images of a given root canal, these Monge images were positioned using photogrammetric methods. Each well-ordered axis pair of a given root canal was put into a common coordinate system resulting in 3D polynomial function of the actual root canal. On the basis of the results gained using 10 samples evaluated with the Friedman statistical test, this description seems to be reproducible. The 3D representation of the root canal may help the clinicians in choosing the optimal instruments and shaping techniques. The root canal axis that is described by the 3D function forms a basis for determination of curvature values and torsion values in each of the axis points. Evaluating these values may also yield a new type of classification.

Algorithms↗

PubMed2001

Predictive validity of the physical disorders axis of the DSM multiaxial diagnostic system.

This paper reports on the predictive validity of the physical disorders axis (axis III) of the DSM multiaxial diagnostic system at 3-year follow-up. A total of 515 general psychiatric patients were assessed with a semistructured procedure that covers all DSM-III diagnoses and axes, and were subsequently followed up for 3 years. Outcome was assessed with several measures of adaptive functioning. Baseline axis III was analyzed according to a) presence of any physical disorder, b) the number of these, c) presence of major chronic physical disorders (MCPD), and d) the number of these. Prediction of impairment in functioning (Strauss-Carpenter Scale), derived from baseline axis III, ranged from a correlation coefficient of .18 when expressed as the presence of any physical disorder to .35 when represented by the number of MCPD. Furthermore, within patients with specific psychiatric disorders, it was found that number of MCPD reached a predictive validity of .55 for patients with dysthymic disorders, .44 for those with anxiety disorders, and .41 for those with major depression. Comparative multiple regression analyses, controlling for demographic and clinical variables, showed that the number of MCPD at baseline was the most important predictor of functioning outcome among patients with dysthymic disorders and major depression. The number of MCPD experienced by general psychiatric patients seems to be an important predictor of future functioning, particularly for patients with certain psychiatric disorders. This points out the importance of considering the relationship between psychiatric and MCPD when conducting systematic clinical assessments towards the prediction of course and outcome.

Adolescent↗

PubMed2002

Isolated fractures of the axis in adults.

UNLABELLED: FRACTURES OF THE ODONTOID: STANDARDS: There is insufficient evidence to support treatment standards. GUIDELINES: Type II odontoid fractures in patients 50 years and older should be considered for surgical stabilization and fusion. OPTIONS: Type I, Type II, and Type III fractures may be managed initially with external cervical immobilization. Type II and Type III odontoid fractures should be considered for surgical fixation in cases of dens displacement of 5 mm or more, comminution of the odontoid fracture (Type IIA), and/or inability to achieve or maintain fracture alignment with external immobilization. TRAUMATIC SPONDYLOLISTHESIS OF THE AXIS (HANGMAN'S FRACTURE): STANDARDS: There is insufficient evidence to support treatment standards. GUIDELINES: There is insufficient evidence to support treatment guidelines. OPTIONS: Traumatic spondylolisthesis of the axis may be managed initially with external immobilization in most cases. Surgical stabilization should be considered in cases of severe angulation of C2 on C3 (Francis Grade II and IV, Effendi Type II), disruption of the C2--C3 disc space (Francis Grade V, Effendi Type III), or inability to establish or maintain alignment with external immobilization. FRACTURES OF THE AXIS BODY (MISCELLANEOUS FRACTURES): STANDARDS: There is insufficient evidence to support treatment standards. GUIDELINES: There is insufficient evidence to support treatment guidelines. OPTIONS: External immobilization is recommended for treatment of isolated fractures of the axis body.

Adult↗

PubMed1982

Lid interaction and toric soft lens axis location.

A group of 15 subjects were fitted with truncated toric soft lenses varying in cylinder power from 1 to 4 D, in 1 D steps, with axes 90 and 180 degrees. After 30 min of wear, the location of the truncation was measured from a slitlamp photograph and calculated from a spherocylindrical over-refraction. Blink-initiated rotation of the lenses was measured by slitlamp photography. Comparison of the location of the truncation of lenses with cylinder at axes 90 and 180 degrees showed no significant difference using matched pair analysis, nor was cylinder power found to effect truncation location. However, analysis of the incidence of acceptable location (truncation within 25 degrees of the horizontal) showed significantly more acceptable locations for those toric lenses with the cylinder at axis 90 degrees (against-the-rule). A significant product moment correlation between the amount of mislocation of the axis and blink-initiated rotation was found. A high correlation was found between axis location measured from photographs and that calculated from over-refraction. However, because of the large variance of the differences between the two values, over-refraction is not considered to be a clinically acceptable method of determining toric lens axis location. The significance of the results of this study are discussed with respect to toric lens design.

Astigmatism↗

PubMed1989

Optical design of intraocular lenses. II. Off-axis performance.

The effect of intraocular lens shape on off-axis performance of model pseudophakic eyes was investigated. Image quality criteria included an optimization procedure, spot diagrams, and the modulation transfer function (MTF). The optimum lens shape varies with lens fitting position, corneal asphericity, and pupil size. An earlier investigation showed that the optimum lens shape for on-axis imagery is approximately plano-convex, with the more curved surface facing the cornea. In this investigation, optimum lens shapes for a 10 degrees off-axis position ranged from near this shape to near the reversed shape, i.e., the more curved surface facing the retina. Because the on-axis case should carry more weight and because conditions favoring the reverse form include small pupils for which image quality is fairly insensitive to variations in lens shape, it is suggested that good forms for intraocular lenses range from plano-convex (curved surface facing cornea) to equi-convex.

Equipment Design↗

PubMed1990

Effect of cyclodeviations on the axis of astigmatism (for patients with superior oblique paresis).

Cyclodeviations may interfere with fusional ability and may also affect the refractive status. If a cyclodeviation is present, the axis of astigmatism determined under monocular viewing conditions will be different from that determined under binocular viewing conditions. The change in the axis should correlate with the amount and direction of the cyclodeviation. We measured the refractive status under monocular and binocular viewing conditions of patients with cyclodeviation of 3 degrees or more and astigmatism of 1.00 D or more. All patients had superior oblique paresis. We then compared the change in the axis of astigmatism to the cyclodeviation measured with the double Maddox rod test. The average change in the axis of astigmatism was 5.0 degrees and the average cyclodeviation was 5.2 degrees. We recommend that all patients with 3 degrees or more of cyclodeviation, 1.00 D or more of astigmatism, and capable of fusion should have their refractive status determined under binocular viewing conditions.

Adult↗

PubMed2004

Astigmatic axis is related to the level of spherical ametropia.

PURPOSE: Against-the-rule (ATR) astigmatism has been shown to be a risk factor for subsequent myopia development. In this study, we evaluated the relationship between astigmatic axis and the level of spherical ametropia in both myopes and hypermetropes. METHODS: Astigmatic axes were analyzed in two distinct cohorts. First, 53 high myopes from families that were recruited for linkage analysis were compared with an age-matched control group derived from family members. Second, cross-sectional data were analyzed for 90,884 subjects attending 19 optometric practices in the north of England. Initially, the relationship between astigmatic axis and cylinder power and between axis and sphere power were analyzed in 21- to 40-year olds and 21- to 30-year olds, respectively, to control for the effects of age. Multivariate logistic regression analysis was then performed using data for all compound astigmats in the cohort to examine the effect of sphere power, cylinder power, age, and sex on the odds of subjects having either ATR or with-the-rule (WTR) astigmatism. RESULTS: In the genetic study cohort, there was an excess of WTR astigmats in the high myopes compared with controls, but this only reached significance for the right eye. In the much larger optometric practice sample, the association of WTR astigmatism with high myopia was highly significant. A parallel increase in WTR astigmatism was also found for high hypermetropes. In addition, the odds of having WTR astigmatism were increased if subjects were young or had a high cylinder power. ATR astigmatism occurred more often with increasing age and in subjects with lower spherical ametropia. Indeed, for 21- to 30-year-old subjects with low myopia (> or =-2.00 DS in the least minus meridian), ATR occurred more often than WTR astigmatism. CONCLUSION: Astigmatic axis was found to be related to the level of ametropia, with both a higher spherical component or higher cylinder power increasing the odds of astigmatism being WTR. Low ametropes, particularly myopes, were more likely to have axes ATR.

Adolescent↗

PubMed2000

A comparison of the Kennedy Axis V and the Global Assessment of Functioning Scale.

In this article, the authors evaluate two brief clinician-scored global assessment instruments used to measure the functioning of adult clients who have a serious mental illness: the Global Assessment of Functioning (GAF) Scale and the relatively new Kennedy Axis V (K Axis). Although both instruments are brief and easy to score, the K Axis provides a multi-dimensional evaluation, while the GAF provides a single, unidimensional picture of a client's functioning. Statistical analyses indicated that both instruments have adequate validity and reliability if the clinicians using them are sufficiently trained. Correlations between the two instruments were high where expected. Statistically significant differential functioning was found for various subgroups. The K Axis was better able to pinpoint this specific differential functioning.

Journal Article↗

PubMed2006

Magnetic resonance imaging abnormalities of neural axis in Lenke type 1 idiopathic scoliosis.

STUDY DESIGN: Patients with Lenke type 1 single thoracic idiopathic scoliosis were included in this prospective study. All patients had preoperative magnetic resonance imaging (MRI). OBJECTIVE: To examine the frequency of neural axis abnormalities and the need for preoperative MRI in this group of patients. SUMMARY OF BACKGROUND DATA: Because of the increasing use of MRI, neural axis abnormalities have been reported in association with certain clinical and radiologic findings in idiopathic scoliosis cases. METHODS: A total of 104 patients (49 juvenile onset and 55 adolescent onset), older than 10 years, were included in the study. The association of neural axis abnormalities with pes cavus, abnormal deep tendon reflexes, age of onset, presence of pain, severity of the frontal plane deformity, and sagittal contours were investigated. RESULTS: All 7 patients with a neural axis abnormality on MRI had an early onset disease, and 6 of them had back pain. Thus, age of onset and back pain seem to be predictive of these abnormalities. Frequency of MRI abnormalities was as high as 45% for patients with back pain in addition to a type IC curve. CONCLUSION: In patients with juvenile idiopathic scoliosis and back pain, preoperative MRI should be performed to eliminate the risk of postoperative neurologic deficits, even if the scoliosis is Lenke type 1. However, in patients with Lenke type 1 idiopathic scoliosis, preoperative MRI studies seem unnecessary if intraoperative neural monitoring is to be performed.

Adolescent↗