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At least 757 records · Page 42Linked to original sources
PubMed2003

[Traumatic spondylolisthesis of the axis].

PURPOSE OF THE STUDY: The study presents a group of patients with traumatic spondylolisthesis of the axis. Views on the treatment of different types of spondylolisthesis vary. The aim of this study was to carry out a retrospective evaluation of the group of patients with this traumatic condition. MATERIAL: In the period from 1995 to 2002, 26 patients with traumatic spondylolisthesis of the axis were treated. They accounted for 5% of all patients admitted to our department for cervical spine injuries. Three types of traumatic spondylolisthesis were distinguished according to the Effendi classification. Type I was diagnosed in seven, type II in 18 patients and type III in one patients. METHODS: Type I traumatic spondylolisthesis was, as a rule, treated conservatively. A halo vest was used in four and a Philadelphia collar in three patients. Patients diagnosed with type II spondylolisthesis were treated surgically from the anterior approach (16 patients) or with a halo vest (two patients). The only patient with a type III fracture was operated on from the anterior approach. RESULTS: Osseous healing was achieved in all patients. No pseudoarthrosis developed and no repeat surgery for infection or osteosynthesis failure was needed. No deterioration of neurological findings was recorded. The range of motion in the cervical spine after healing was not affected. DISCUSSION: Views on the classification and therapy of traumatic spondylolisthesis of the axis are diverse. The greatest diversity is associated with making a decision on whether the injury is unstable and requires surgical treatment or not. Further arguments are related to the use of the most suitable approach. Treatment from the anterior approach is prevailing. Type III fractures are rare and must always be treated surgically. CONCLUSIONS: Methods for treatment of traumatic spondylolisthesis of the axis are currently a topic of dispute. The decisive factor for therapy is whether the injury is stable or unstable. When instability is present, anterior C2-3 spondylodesis completed with plate osteosynthesis is the method of choice. Stable injuries are treated by the application of a halo vest or Philadelphia collar.

Adolescent↗
PubMed1985

[Nontraumatic spondylolysis of the axis vertebra].

A case of nontraumatic spondylolysis of the axis vertebra is presented. A 55-year-old man suddenly experienced nausea and dizziness on January 15, 1984 when he rotated his neck toward the left. Since this episode, he experienced the same attacks twice. On examination, the patient was afraid of moving his neck abruptly and on gradual hyperextension of his neck, he started to complain of slight dizziness. But otherwise no abnormalities of motor, sensory and cerebellar functions were noticed. Lateral view of plain films of the cervical spine revealed a bilateral bony defect in the lamina of the axis vertebra. The surface of the bony margin around the defect seemed to be well corticated and smooth. There was no spondylolisthesis between the second and the third cervical vertebra. CT scan of the axis vertebra also showed bilateral true bony defect, not in the pars interarticularis but in the inferior articular process of the axis vertebra. Spondylolysis with or without spondylolisthesis of the cervical vertebrae is relatively rare and about 48 cases of the cervical spondylolysis have been reported in the previously published literature.

Axis, Cervical Vertebra↗
PubMed1999

Left-right axis malformations associated with mutations in ACVR2B, the gene for human activin receptor type IIB.

Targeted disruption of the mouse activin receptor type IIB gene (Acvr2b) results in abnormal left-right (LR) axis development among Acvr2b-/- homozygotes [Oh and Li, 1997: Genes Dev 11:1812-1826]. The resulting malformations include atrial and ventricular septal defects, right-sided morphology of the left atrium and left lung, and spleen hypoplasia. Based on these results, we hypothesized that mutations in the type IIB activin receptor gene are associated with some cases of LR axis malformations in humans. We report here characterization of the ACVR2B genomic structure, analysis of ACVR2B splice variants, and screening for ACVR2B mutations among 112 sporadic and 14 familial cases of LR axis malformations. Two missense substitutions have been identified, one of which appears in two unrelated individuals. Neither of these nucleotide changes has been found in 200 control chromosomes. We conclude that ACVR2B mutations are present only rarely among human LR axis malformation cases.

Activin Receptors, Type II↗
PubMed1998

Isoseparation curves: a mechanism for optimizing off-axis dose homogeneity of intact breast irradiation.

The purpose of this paper is to determine whether using off-axis isoseparation curves to optimize the collimator rotation angle improves dose homogeneity. Eleven intact breast irradiation patients underwent computerized tomography (CT) treatment planning with 1 cm abutting slices. Central plane treatment planning, using 6 MV photons, tissue inhomogeneity corrections, and isocentric opposed tangent treatment fields, was performed. Collimators were rotated to match chest wall slope through the use of a beam's-eye-view setting. Patient separations were measured from the apex of the breast to the posterior field border on each axial CT slice. Sagittal-plane isoseparation curves were constructed from these measurements. Using these curves, the collimator rotation that minimized off-axis separation differences was determined. A comparison of off-axis dose inhomogeneity was performed for patients with a > or =10 degrees difference between this optimized collimator angle and the angle determined by chest wall slope. These comparative treatment plans differed only with respect to collimator angle rotation. The mean optimal collimator rotation angle differed significantly from the mean rotation angle which matched the chest wall slope (5.4 degrees vs. 11 degrees, respectively, P < 0.001). Four of the 11 patients had rotation angle differences of 10 degrees. In these patients, the optimization of collimator angle reduced the percentage of breast volume to "that" received > or =110% of the prescribed dose. For the patient with the largest breast size to the patient with the smallest breast size the decreases were, respectively, 5% (15% to 10%), 3% (24% to 21%), 1% (4% to 3%), and 1% (0.9% to 0%). The mean reduction in dose inhomogeneity was greatest in the inferior breast quadrants. At 6 cm and 4 cm off axis, the mean reductions in the percentages of the breast tissue to "that" received 110% of the prescribed dose were respectively 15.1% and 5.3 %. Optimizing the collimator angle through the use of isoseparation curves decreases dose inhomogeneity. The greatest improvements are in the inferior quadrants of the intact breast. The improved dose homogeneity may have clinical relevance in the treatment of patients with large breast sizes.

Breast↗
PubMed1989

Axis determination in insect embryos.

The principles of pattern formation in insects have been studied extensively using classical experimental approaches. In Drosophila, a powerful combination of genetics and transplantation experiments, as well as molecular biology, has helped to elucidate the mechanisms that operate during oogenesis to establish a set of positional cues required for axis determination in the early embryo. These studies suggest the following model: for the anteroposterior axis of the embryo, three groups of maternal genes define three largely independent systems that determine (1) the anterior segmented region of head and thorax, (2) the posterior segmented region of the abdomen, and (3) the terminal non-segmented regions of acron and telson. In contrast, the dorsoventral egg axis appears to require only one system. In each of the four systems, one key gene has an active product that is unequally distributed in the egg. This product provides the spatial signal for the region-specific activation of the transcription of at least one zygotic target gene. The other members within each group serve accessory functions such as determining the correct spatial distribution of the key gene products or controlling their localized activation. The unique expression patterns of the individual zygotic target genes provide a coarse spatial framework which is then refined by the action and interaction of zygotic genes. The notion of three independent systems determining the anteroposterior axis is at variance with a previous model (Meinhardt 1977, Nüsslein-Volhard 1979) of only one gradient, with a high point at the posterior pole, determining a series of states in a concentration-dependent manner. Concentration-dependent determination of more than one quality is likely to occur in the anterior and the dorsoventral system. In contrast, position and polarity within the posterior pattern appear to depend largely on the interaction between gap genes expressed in neighbouring regions rather than on the concentration of the posterior signal.

Animals↗
PubMed1994

Hypothalamic-pituitary-adrenal axis perturbations in patients with fibromyalgia.

OBJECTIVE: To examine basal and stimulated hypothalamic-pituitary-adrenal (HPA) axis and related hormone levels, including adrenocorticotropin (ACTH), cortisol, arginine vasopressin (AVP), and neuropeptide Y (NPY), in patients with fibromyalgia (FM). METHODS: Basal and ovine corticotropin-releasing hormone (oCRH)-stimulated HPA axis function were assessed in 12 patients with FM and in age- and sex-matched normal subjects. Basal plasma AVP levels and AVP release after postural change were assessed, and plasma NPY levels were measured in the same samples. RESULTS: Patients with FM had low 24-hour urinary free cortisol, but normal peak and elevated trough plasma cortisol levels, compared with normal subjects. The net integrated ACTH response to oCRH in FM was not significantly different from that in normal subjects, but tended toward an exaggerated response. There was a significant decrease in net integrated cortisol response to oCRH in FM patients, indicating adrenal hyporesponsiveness. AVP levels were not significantly different between FM patients and control subjects, but variability was greater among the FM patients. Plasma NPY levels were significantly lower in FM patients than in normal subjects. CONCLUSION: These data support the view that HPA axis function is perturbed in patients with FM. Further study is required to ascertain the cause of HPA axis perturbations and their relationship to symptoms in patients with FM.

Adrenocorticotropic Hormone↗
PubMed1985

Transcutaneous Doppler ultrasound measurement of coeliac axis blood flow in man.

Transcutaneous Doppler ultrasound was used to measure coeliac axis blood flow in 42 normal subjects in the fasting state and in 10 subjects following a liquid meal. A Duplex scanner was used and coeliac axis blood flow was estimated by calculating the instantaneous average velocity of blood flow over the cardiac cycle. Both the diameter of the vessel and the angle between the vessel and the beam were measured from real time imaging. The mean (+/- s.e.m.) of coeliac axis blood flow was 703 +/- 24 ml/min. There was no difference in the results between the sexes nor any correlation between flow and age. The mean coefficient of variability was 7.8 per cent in a 1 day test and 9.2 per cent in a 2 day test. Coeliac axis blood flow increased by 38 per cent immediately after the end of ingestion of the meal and declined to 29 per cent 5 min and 24 per cent 10 min later.

Adult↗
PubMed1999

Electrocardiographic screening for emphysema: the frontal plane P axis.

BACKGROUND: Because the most characteristic and sensitive electrocardiographic (ECG) correlate of pulmonary emphysema in adults is verticalization of the frontal plane P-wave vector (P axis), we investigated its strength as a lone criterion to screen for obstructive pulmonary disease (OPD) in an adult hospital population. METHODS: In all, 954 consecutive unselected ECGs were required to yield 100 with P axis > or = +70 degrees (unequivocally negative P in a VL during sinus rhythm) and pulmonary function tests. and 100 with P axis < or = +50 degrees (unequivocally positive P-aVL). RESULTS: Obstructive pulmonary disease by both pulmonary function test and clinical criteria was present in 89 of 100 patients with vertical P axes and 4 of 100 patients without OPD. CONCLUSION: The high sensitivity (89% for this series) and high specificity (96%) makes vertical P axis a useful screening criterion. Its at-a-glance simplicity makes it "user-friendly."

Adult↗
PubMed2002

Anteroposterior axis formation in Xenopus limb bud recombinants: a model of pattern formation during limb regeneration.

We previously showed that recombinant limb buds with dissociated and reaggregated mesenchyme develop more than 30 digits in Xenopus laevis, which exhibits different capacities for limb regeneration at different developmental stages (Yokoyama et al. [1998] Dev Biol 196:1-10). Cell-cell contact among anterior- and posterior-derived mesenchymal cells is required for anteroposterior (AP) axis formation of recombinant limbs in an intercalary manner. However, whether one-way induction from posterior cells to anterior cells as proposed by the polarizing zone model or interactions between anterior and posterior cells evoke the AP axis formation in recombinant limbs remains unclear. In this study, we found, by a combination of X-ray irradiation and a recombinant limb technique, that not one-way induction but interactions between anterior and posterior cells accompanied by cell contribution are indispensable for AP axis formation in recombinant limbs. Shh was expressed in posterior-derived not anterior-derived cells. We propose that the recombinant limb is an excellent model for examining the axis formation mechanism in regenerating limbs because, as in recombinant limbs, cell-cell contact among cells derived from different positions of an amputation plane occurs in the blastema of regenerating limbs.

Animals↗
PubMed2005

Specification of embryonic axis and mosaic development in ascidians.

Setting up future body axes is the first important event before and at the beginning of embryogenesis. The ascidian embryo is a classic model that has been used to gain insight into developmental processes for over a century. This review summarizes advances made in this decade in our understanding of the developmental processes involved in the specification of the embryonic axes and cell fates during early ascidian embryogenesis. Maternal factors, including mRNAs, are translocated to specific regions of the egg by cytoplasmic and cortical reorganization, so-called ooplasmic segregation, and specify the animal-vegetal axis and the one perpendicular to it, which is defined as the anteroposterior axis in ascidians. Some postplasmic/PEM RNAs that are anchored to cortical endoplasmic reticulum are brought to the future posterior pole of fertilized eggs, and play crucial roles in posterior development. Following specification of the animal-vegetal axis, nuclear localization of beta-catenin takes place in the vegetal blastomeres; this occurrence is important for the acquisition of the vegetal character of the blastomeres in later development. Positioning of these maternal factors lead to subsequent cell interactions and zygotic gene expression responsible for axis establishment and for cell fate specification. We describe how endoderm blastomeres in the vegetal pole region emanate inductive signals mainly attributable to fibroblast growth factor. Marginal blastomeres next to endoderm blastomeres respond differently in ways that are determined by intrinsic competence factors. Expression patterns of developmentally important genes, including key transcription factors of each tissue type, are also summarized.

Animals↗
PubMed1996

The heritability of bone mineral density, ultrasound of the calcaneus and hip axis length: a study of postmenopausal twins.

Population based studies have demonstrated that having a first degree relative with a hip fracture is predictive of future hip fractures. Postmenopausal bone mineral density (BMD), ultrasound of calcaneus and hip axis length are associated with hip fracture, with the association for ultrasound and hip axis length being independent of BMD. The aim of this study was to determine the genetic component of these three important risk factors. We performed a classical twin study using 500 normal female twins, 128 identical and 122 non-identical pairs, aged 50 to 70 years. We measured bone mineral density at multiple sites, hip axis length (distance from the inner rim of the acetabulum to the greater trochanter), broadband ultrasound attenuation and velocity of sound of the calcaneus. Bone density had a strong genetic component at all sites with estimates of heritability ranging from 0.46 to 0.84. Hip axis length and velocity of sound had major genetic components with estimates of 0.62 and 0.61 respectively, which remained virtually unchanged after adjustment for bone mineral density. Broadband ultrasound attenuation had a moderate genetic component with an estimate of 0.53, which was reduced further to 0.45 after adjustment for BMD. In summary, all three bone measurements, which are independently associated with hip fracture, are independently heritable. This study suggests that a combination of different genetic factors acting on the structure, dimensions and density of bone may explain the importance of family history as a risk factor for hip fracture.

Aged↗
PubMed2005

Impairment and distress associated with symptoms of male-typed and female-typed DSM-IV Axis-I disorders.

Recent research has established a pattern of impairment and distress associated with the symptoms of DSM-IV Axis-II disorders such that personality disorders occurring more commonly among males are associated with more social and occupational impairment, but less personal distress, than personality disorders occurring more commonly among females. The current study examined whether a similar pattern exists for DSM-IV Axis-I disorders. Lay judges (N = 206) rated the social impairment, occupational impairment, and personal distress associated with the symptoms of six male-typed and six female-typed Axis-I disorders. Impairment and distress were associated with male-typed and female-typed Axis-I disorders in the same manner as personality disorders. Reasons for the emphasis of social and occupational impairment among male-typed disorders and distress among female-typed disorders are discussed.

Adolescent↗
PubMedDate not supplied

Chemical shift artifact along the section-select axis.

Chemical shift artifact (CSA), familiar to radiologists along the frequency-encoding axis, also occurs along the section-select axis. The authors observed a case in which CSA mimicked a renal mass. Subsequent retrospective analysis of 50 abdominal magnetic resonance (MR) imaging studies was performed to assess occurrence of CSA adjacent to the upper and lower renal poles. CSA along the section-select axis was observed in 76% of cases and adjacent to 39% of all renal poles imaged. CSA along the section-select axis is common in abdominal MR imaging and may occasionally mimic disease.

Abdomen↗
PubMedDate not supplied

Assessment of regional left ventricular long-axis motion with MR velocity mapping in healthy subjects.

The pattern of left ventricular long-axis motion during early diastole was assessed with magnetic resonance (MR) velocity mapping in 31 healthy volunteers. Regional long-axis velocity varied with time and position around the ventricle. During systole, the base descended toward the apex. The greatest magnitude of long-axis velocity occurred during early diastole. The lateral wall had the highest velocity (140 mm/sec +/- 40 [mean +/- standard deviation]); the anterior and inferior walls had lower velocities (96 mm/sec +/- 27 and 92 mm/sec +/- 34, respectively). The inferoseptal area consistently had the lowest velocities (87 mm/sec +/- 40). Absolute values of peak early-diastolic velocity declined with age (r = -.64, P < .001). Peak early-diastolic velocity was not dependent on heart rate (r = .014, P = .94). Regional variations in left ventricular wall motion were seen. MR velocity mapping is a useful technique for assessing regional left ventricular long-axis heart function.

Adult↗
PubMed2005

Myocardial first-pass perfusion assessment using rotational long-axis MRI.

PURPOSE: To study a first-pass myocardial perfusion imaging method, such that long-axis imaging slices are obtained rotationally around the short-axis centroid of the left ventricular cavity, in order to improve myocardial coverage and better delineate the basal and apical myocardium. MATERIALS AND METHODS: This rotational long-axis (RLA) method was examined in 12 volunteers and compared to the perfusion images from conventional parallel short-axis (PSA) acquisitions in terms of the contrast to noise ratio (CNR), relative signal upslope and myocardial coverage. Both RLA and PSA first-pass perfusion images were acquired on each volunteer with otherwise identical imaging parameters using the partial Fourier saturation recovery steady state gradient echo sequence with refocused magnetization (TrueFISP) technique. RESULTS: Compared to PSA, RLA perfusion images with identical imaging parameters on the same subject exhibit an average of near 30% improvement in total myocardial area imaged. In addition, true basal and apical myocardium was seen on RLA, but not on PSA. The mean CNR and relative upslope were similar between the two techniques. CONCLUSIONS: This RLA perfusion imaging scheme is superior to the conventional PSA approach in terms of extent myocardial coverage and delineation of basal and apical regions of the left ventricle.

Aged↗
PubMed2002

3D MRA coronary axis determination using a minimum cost path approach.

A method is introduced to automatically find the coronary axis based on two or more user-defined points, even in the presence of a severe stenosis. The coronary axis is determined by finding a minimum cost path (MCP) in a feature image in which the tubular-like structures are enhanced. The results of the proposed method were compared with manually drawn central axes to estimate the accuracy. In 32 3D TFE-EPI acquisitions of patients and volunteers, 14 right coronary arteries (RCAs), 15 left anterior descending arteries (LADs), and eight left circumflex arteries (LCXs) were manually tracked twice by two operators to determine a reference axis and to assess the inter- and intra-user variability. On average, the maximum distance to the reference axis, based on only two user-defined points, is less than 1.5 mm; the average distance is around 0.65 mm, which is less than the average in-plane resolution. The results of the method are comparable to those of the manual operators.

Coronary Stenosis↗
PubMed1999

Hypothalamo-pituitary-adrenal axis responses to lipopolysaccharide in male and female rats with adjuvant-induced arthritis.

We have previously demonstrated that rats with adjuvant-induced arthritis (AA) are unable to mount a hypothalamo-pituitary-adrenal (HPA) axis response to either psychological or physical stress. In the present study we have taken male and female rats with AA and injected these with lipopolysaccharide (LPS) as an acute immune challenge and assessed the effects of this challenge at all levels of the HPA axis. We have demonstrated that, in contrast to acute stress, there is an activation of the HPA axis in male AA rats in response to acute immune challenge which occurs at all levels of the HPA axis. The hypothalamic and pituitary response to LPS is intact in the female AA rat. However, there appears to be an impaired adrenal responsiveness in the AA female given LPS. The non-AA female is able to respond to LPS suggesting that this defect is not inherent but is a reaction to the development of inflammation. This hyporesponsiveness has major implications for the ability of the organism to survive infections or immune challenges which are potentially life threatening in the absence of release of anti-inflammatory glucocorticoids from the adrenal cortex. The implications of these changes in the female on the subsequent development of the disease and the mechanisms mediating these effects may provide a better understanding of the gender differences underlying susceptibility to autoimmune diseases.

Adrenocorticotropic Hormone↗
PubMed2000

The spd-2 gene is required for polarization of the anteroposterior axis and formation of the sperm asters in the Caenorhabditis elegans zygote.

In the Caenorhabditis elegans zygote, polarization of the anteroposterior (AP) axis occurs during a brief period of reorganization that follows fertilization and results in the establishment of discrete cytoplasmic and cortical domains. In the cytoplasm, germ-line or P granules are circulated by an actomyosin-driven fountain flow of cytoplasm and localize to the posterior, while in the cortex, two proteins required for AP polarity, PAR-2 and PAR-3, localize to the posterior and the anterior, respectively. The identity of the positional cue that determines AP axis orientation is not known, although it has been postulated to be a component of the sperm pronucleus/centrosome complex (SPCC) as the position of the SPCC correlates with the orientation of the AP axis and the direction of the fountain flows. Here, we show that mutations in the spd-2 gene disrupt polarization of the AP axis. In mutant zygotes, the fountain flow of cytoplasm and associated asymmetric cortical contractions are absent, P granules do not localize, and cortical PAR-3 does not become asymmetrically distributed. Interestingly, cortical PAR-2 localizes randomly to either or both poles. The random positioning of PAR-2 requires PAR-3 and indicates that a spd-2-dependent mechanism normally modulates PAR-2/PAR-3 interactions to correctly position PAR-2 at the posterior. spd-2 mutations also disrupt formation of the SPCC by delaying and attenuating the formation of sperm asters until after the period of reorganization, suggesting that spd-2 mutations disrupt formation of the positional cue. Our results also indicate that sperm asters are not essential for pronuclear migration but are required for rapid female pronuclear movement and premitotic positioning of the pronuclei.

Animals↗