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PubMed2003

Effect of composition changes on the structural relaxation of a binary mixture.

Within the mode-coupling theory for idealized glass transitions, we study the evolution of structural relaxation in binary mixtures of hard spheres with size ratios delta of the two components varying between 0.5 and 1.0. We find two scenarios for the glassy dynamics. For small size disparity, the mixing yields a slight extension of the glass regime. For larger size disparity, a plasticization effect is obtained, leading to stabilization of the liquid due to mixing. For all delta, a decrease of the elastic moduli at the transition due to mixing is predicted. A stiffening of the glass structure is found as is reflected by the increase of the Debye-Waller factors at the transition points. The critical amplitudes for density fluctuations at small and intermediate wave vectors decrease upon mixing, and thus the universal formulas for the relaxation near the plateau values describe a slowing down of the dynamics upon mixing for the first step of the two-step relaxation scenario. The results explain the qualitative features of mixing effects reported by Williams and van Megen [Phys. Rev. E 64, 041502 (2001)] for dynamical light-scattering measurements on binary mixtures of hard-sphere-like colloids with size ratio delta=0.6.

Journal Article↗
PubMed2004

Compensation of corneal horizontal/vertical astigmatism, lateral coma, and spherical aberration by internal optics of the eye.

Both the anterior surface of the cornea and the internal optics (the posterior cornea, crystalline lens) contribute to the aberration of a wavefront passing through the eye. Artal, Guirao, Berrio, and Williams (2001) reported that the wavefront aberrations produced by the internal optics offset, or compensate for, the aberrations produced by the cornea to reduce ocular wavefront aberrations. We have investigated the wavefront aberrations of the cornea, internal optics, and complete eye on both the population and individual level to determine which aberrations are compensated and probable paths leading to that compensation. The corneal and ocular aberrations of 30 young subjects at relaxed accommodation were measured with the Topcon Wavefront Analyzer, which simultaneously measures refraction, corneal topography (videokeratoscope), and wavefront aberrations (Hartmann-Shack sensor). We found strong evidence for compensation of horizontal/vertical (H/V) astigmatism (Zernike term Z5) lateral coma (Z8) and spherical aberration (Z12). H/V astigmatism compensation is scaled for each individual, suggesting that it is actively determined by a fine-tuning process. Spherical aberration shows no individual compensation, suggesting that is a passive result of genetically determined physiology. Lateral coma shows individually scaled compensation, some of which may be attributable to eccentricity of the fovea.

Accommodation, Ocular↗
PubMed2000

Innovations and strategies for the development of anticancer vaccines.

In 1893, William Coley reported the spontaneous regression of a soft tissue sarcoma in several patients suffering from acute bacterial infections. Although this observation occurred over a century ago, the concept of anticancer vaccines and the immunotherapy of cancer has only recently seemed plausible. A myriad of specific and non-specific immunostimulatory approaches have been tested throughout the years with only a modicum of success. Most of these approaches were doomed from the outset since they were based on false or inadequate knowledge of tumour immunology. Recent advances in our understanding, most notably the identification of genes encoding for cancer regression antigens, currently permit investigators to pursue a more cogent strategy to develop novel and specific anticancer vaccine approaches. Several of these approaches are currently being tested in clinical trials and have already yielded exciting results. However, a number of immunologic and host obstacles to the successful application of anticancer vaccines remain. This editorial will provide an update on the clinical status of anticancer vaccines and review areas of promising research initiatives.

Adjuvants, Immunologic↗
PubMed1989

Lumboperitoneal shunt combined with myelotomy for treatment of syringohydromyelia.

This study was undertaken to investigate whether a direct communication between the fourth ventricle and the syrinx exists in the majority of patients with syringohydromelia and whether intraspinal pressure plays a role in the pathogenesis of this disorder. A series of 13 patients with syringohydromyelia delineated by magnetic resonance (MR) imaging was reviewed, and the intracranial pressure (ICP) and lumbar spinal pressure (LSP) were recorded concomitantly in three patients. Lumboperitoneal shunting was performed in seven patients, six of whom also underwent myelotomy of the caudal spinal cord. Magnetic resonance imaging visualized a cerebrospinal fluid (CSF) channel connecting the fourth ventricle with the syrinx in only one of the 13 patients, and in the remaining 12 patients it revealed a long segment of the spinal cord free of syrinx below the fourth ventricle. This finding is in accordance with recent MR studies of syringohydromyelia. The concomitant recording of ICP and LSP in our patients who had myelomeningocele and Chiari II malformation showed findings contradicting the reports of Williams. Lumbar spinal pressure was equal to ICP under steady-state conditions, and was elevated by straining or crying more markedly than ICP. Craniospinal pressure dissociation with ICP greater than with LSP, as described by Williams, was not observed. Lumboperitoneal shunting concomitant with myelotomy and syringopleural shunting 1 month after myelotomy resulted in marked and sustained shrinkage of the syrinx and neurological improvement in four patients. It was concluded that the majority of patients with syringohydromyelia and Chiari malformation lack a direct communication connecting the fourth ventricle with the syrinx. The results suggest that CSF moves under pressure into the spinal cord, contributing to the formation and maintenance of the syrinx, and that LP shunting combined with myelotomy can effect shrinkage of the syrinx.

Adolescent↗
PubMed1978

One fine day.

Explore the source record for details and available documents.

Chimera↗
PubMed1995

[CT analysis of aortic cobwebs in aortic dissection].

Contrast-enhanced CT images in patients with acute or chronic aortic dissection were evaluated for the purpose of determining the clinical usefulness of "aortic cobwebs", which were originally reported by Williams et al. as an anatomical marker of the false lumen. Aortic cobwebs were detected in 13 of 44 cases (30%), demonstrating as low density structures in the false lumen continuing from the intimal flap. The aortic cobwebs were mainly linear in shape, and the size ranged from 5 x 1 to 15 x 3 mm (mean: 9 x 2 mm). Aortic cobwebs were more frequently demonstrated in chronic than in acute cases, and were more often detected in the abdominal aorta. Follow-up CT examinations of the cobwebs revealed no interval change in six cases, disappearance in three cases and thickening in one case. There was no significant correlation between the sequential changes in the cobwebs and dilatation or thrombus formation in the false lumen. Aortic cobwebs seem to represent partially residual bands of the aortic media incompletely sheared from the aortic wall during the initial processes of aortic dissection. These structures are considered to be a reliable anatomic marker and to be useful for CT identification of the false lumen in aortic dissection.

Adult↗
PubMed2004

Soybean cultivars 'Williams 82' and 'Maple Arrow' produce both urea and ammonia during ureide degradation.

The ability of two soybean (Glycine max L. [Merrill]) cultivars, 'Williams 82' and 'Maple Arrow', which were reported to use different ureide degradation pathways, to degrade the ureides allantoin and allantoate was investigated. Protein fractions and total leaf homogenates from the fourth trifoliate leaves of both cultivars were examined for the ability to evolve either (14)CO(2) or [(14)C]urea from (14)C-labelled ureides in the presence of various inhibitors. (14)CO(2) evolution from [2,7-(14)C]allantoate was catalysed by 25-50% saturated ammonium sulphate fractions of both cultivars. This activity was inhibited by acetohydroxamate (AHA), which has been used to inhibit plant ureases, but not by phenylphosphorodiamidate (PPD), a more specific urease inhibitor. Thus, in both cultivars, allantoate may be metabolized by allantoate amidohydrolase. This activity was sensitive to EDTA, consistent with previous reports demonstrating that allantoate amidohydrolase requires manganese for full activity. Total leaf homogenates of both cultivars evolved both (14)CO(2) and [(14)C]urea from [2,7-(14)C] (ureido carbon labelled) allantoin, not previously reported in either 'Williams 82' or in 'Maple Arrow'. In situ leaf degradation of (14)C-labelled allantoin confirmed that both urea and CO(2)/NH(3) are direct products of ureide degradation. Growth of plants in the presence of PPD under fixing and non-fixing conditions caused urea accumulation in both cultivars, but did not have a significant impact on total seed nitrogen. Urea levels were higher in N-fixing plants of both cultivars. Contrary to previous reports, no significant biochemical difference was found in the ability of these two cultivars to degrade ureides under the conditions used.

Allantoin↗
PubMed2001

Long-term outcome of 104 patients after lumbar sequestrectomy according to Williams.

OBJECTIVE: The authors report the late outcome of 104 consecutive patients after Williams' sequestrectomy for virgin lumbar disc herniation. METHODS: The clinical records and the mailed questionnaires of 38 women and 66 men operated consecutively between March 1991 and November 1993 were analyzed retrospectively. In these 104 patients, 105 Williams' sequestrectomies were performed. RESULTS: The mean age at operation was 50.5 years (range, 23.2-86.7 yr), and follow-up ranged from 4.1 to 6.9 years (mean, 5.3 yr). Success rates, including excellent, good, and fair results, were 92.5%, 94.7%, and 93.3% for lumbalgia, radicular pain, and neurological dysfunction, respectively. Only a few patients did not improve or presented with worsened symptoms. Three of four patients with cauda equina syndrome recovered immediately after the intervention. There were eight (7.7%) minor postoperative complications, which were treated conservatively. Three women and three men (5.8%) underwent a revision procedure for a recurrent lumbar disc herniation at the same level after 0.4 to 3.1 years (mean, 1.8 yr). Two (1.9%) of these patients underwent further operations because of reherniation, and they required internal instrumentation eventually because of failed back surgery syndrome. CONCLUSION: Williams' conservative approach with sequestrectomy alone is a safe operative modality. It should be used whenever possible. As demonstrated in our series with a long follow-up time, the results are as favorable as or better than results after standard microsurgical lumbar discectomy with curettement of the interspace. Whether the incidence of failed back surgery syndrome can be reduced by this approach remains to be proved.

Adult↗
PubMed2006

Cortical dysplasia of the left temporal lobe might explain severe expressive-language delay in patients with duplication of the Williams-Beuren locus.

We report on a new duplication case of 7q11.23, reciprocal of the Williams-Beuren (WB) deletion. The patient, a 13-year-old girl, was ascertained within an array-CGH screening of patients with epilepsy and neuronal migration defects. Similarly to the first reported patient, she showed serious difficulties in expressive language in the absence of severe mental retardation and marked dysmorphic features. Magnetic resonance imaging (MRI) of the brain revealed an abnormal development of the cerebral cortex in the left temporal lobe, which showed a simplified gyral pattern, and increased cortical thickness. This finding, which might explain poor language development, suggests that the WB critical region might harbour a dosage-sensitive gene controlling the molecular machinery of neuronal migration, with regional specificity and lateralization. It will be important to confirm our findings in newly diagnosed patients with dup(7)(q11.23). We expect to detect many more patients with the same duplication using widespread clinical implementation of high-resolution genome analysis.

Chromosomes, Human, Pair 7↗
PubMed1999

Elevated ambulatory blood pressure in 20 subjects with Williams syndrome.

Previous studies report conflicting frequencies of hypertension in cohorts of patients with Williams syndrome (WS). We studied blood pressure (BP) in WS using 24-hour ambulatory BP monitoring. This technique reliably measures day- and nighttime BP in a subject's natural environment and provides better prognostic information on long-term risks of hypertension than casual BP determinations. Twenty WS subjects evaluated through a multidisciplinary WS clinic and 35 age and gender-matched controls were studied. We found that WS subjects had significantly higher ambulatory BP than controls. After controlling for age, sex, and weight, the diagnosis of WS added approximately 10 mmHg to mean daytime and nighttime BPs. Hypertension, as defined by elevated mean daytime BP, was present in 40% of WS subjects versus 14% of controls (P < 0.05); among the children studied this difference was even more dramatic with 46% of WS children versus 6% of control children classified as hypertensive (P = 0.01). We also demonstrated normal diurnal BP variation but no evidence of a "white coat" effect or increased BP variability. Interestingly, parental reporting of a history of infantile hypercalcemia was strongly associated with the presence of hypertension (P = 0.008). Our data demonstrate that both children and adults with WS have higher mean BP and higher frequency of hypertension than healthy controls. Thus, elevated BP readings in the office setting should not be dismissed but require more thorough assessment.

Adolescent↗
PubMed1998

[A surgical case of supravalvular aortic stenosis with severe hypoplastic ascending aorta (diffuse type) in Williams-Beuren syndrome].

We report a six-year-old boy who underwent ascending aortic reconstruction for supravalvular aortic stenosis of diffuse type associated with Williams-Beuren syndrome. The diagnosis was first made at the age of six months. Because of progressive left ventricular hypertrophy, cardiac catheterization was performed at the age of five years and showed left ventricular pressure of 200 mmHg, the ascending aortic pressure of 202 mmHg, the descending aortic pressure of 115 mmHg, and left ventricular end-diastolic volume of 33.5 ml (90% of normal). Whole ascending aorta except sinus Valsalva was severely hypoplastic, so called diffuse type of supravalvular aortic stenosis. The ascending aorta was only 6.3 mm in diameter, whereas the diameter of the aortic annulus was 20.6 mm. The ascending aortic reconstruction of Doty's type was performed from the aortic root to the distal aortic arch with a equine pericardium reinforced by Dacron velour using selective perfusion to the right bracheocepharic artery, the left common carotid artery and the right femoral artery to avoid circulatory arrest. Postoperative course was uneventful and post operative catheterization revealed left ventricular pressure of 128 mmHg, the ascending aortic pressure of 126 mmHg and the descending aortic pressure of 90 mmHg. Mild residual pressure gradient was probably due to hypoplastic descending aorta. In conclusion, patch aortic reconstruction for ascending aorta under selective cerebral perfusion for a six-year old boy can be performed without postoperative neurological complication.

Aorta↗
PubMed2006

[Partial anomalous pulmonary venous connection to the high portion of the superior vena cava associated with ventricular septal defect repaired with williams method using right atrial flap: report of a case].

A 3-year-old boy suffered from the poor body weight gain under the diagnosis of partial anomalous pulmonary venous connection (PAPVC) to the high portion of the superior vena cava (SVC) associated with ventricular septal defect (VSD) and intact atrial septum (IAS). Preoperative cardiac catheterization revealed the pulmonary to systemic flow ratio 2.6 and mean pulmonary arterial pressure of 21 mmHg. He successfully underwent surgical repair with Williams method using right atrial (RA) flap out and VSD patch closure. Postoperative course was uneventful and echocardiography demonstrated no obstruction at the both routes of neo-SVC and neo-right upper pulmonary venous return.

Child, Preschool↗
PubMed1999

Visuo-spatial and linguistic abilities in a twin with Williams syndrome.

The present study reports a case of dizygotic twins, one boy with Williams syndrome (WS) and one typically developing girl, and compares their neuropsychological profiles. The goal of the present authors was to verify whether the child with WS displayed a cognitive profile which is unique to the syndrome. Several tests designed to assess visuo-perceptual, visuo-motor, linguistic and memory abilities were administered to both children when they were 10.9 years old. Compared to his sister, the boy with WS displayed a homogeneous developmental delay in both non-verbal and verbal abilities. He achieved a level of performance similar to his sister only in facial recognition, phonological word fluency and memory for phonologically similar words. Furthermore, despite the overall delayed performance of the boy, both the twins displayed a cognitive profile characterized by strength in lexical comprehension and relative weakness in visuo-motor abilities.

Child↗
PubMed1998

Cognitive functioning in adults with Williams syndrome.

This paper reports the results of cognitive, linguistic, and academic assessments in a representative sample of 62 adults with Williams syndrome. The average age of the group was 26 years and their mean full scale IQ was 61. Differences between Verbal and Performance IQ, and between receptive and expressive language skills, were smaller than generally found in studies of children with this condition. However, an examination of subtest scores revealed an almost identical cognitive profile to that found in children. Skills in other areas, such as reading, spelling, arithmetic, and social adaptation remained at a low level, with functioning generally being around a 6-8-year age equivalent. The consistency of reports on intellectual abilities in both child and adult studies of individuals with Williams syndrome lends increased support to the notion of a syndrome specific pattern of cognitive, linguistic, and adaptive functioning.

Adolescent↗
PubMed1991

Case report: computed tomography findings in Williams-Campbell syndrome.

Williams-Campbell syndrome is a rare type of cystic bronchiectasis that is due to defective cartilage of fourth-to sixth-order bronchi. The diagnosis has been made either at autopsy or by bronchographic findings. The article describes an adult case of this syndrome with CT findings that are characteristic of this entity. CT showed areas of emphysematous lung parenchyma distal to the dilated bronchi, suggesting bronchiolitis obliterans secondary to proximal cystic bronchiectasis. These findings are useful in differentiating Williams-Campbell syndrome from other causes of cystic bronchiectasis, thus obviating bronchography.

Bronchiectasis↗
PubMed1992

Williams syndrome in adults.

There are few published reports of adults with Williams syndrome (WS). We have evaluated ten adult WS patients. The patients in our study were very variable in clinical presentation, ranging from severely affected patients with complicated medical histories to mildly affected patients who are generally in good health. Cardiovascular anomalies and hypertension were frequent. Supravalvular aortic stenosis was seen in four patients, mitral valve prolapse in three, bicuspid aortic valve in one, valvular aortic stenosis in one, and pulmonary stenosis with right ventricular hypertrophy in one. Typical facial features included stellate irides, prominent cheeks, full lips, and micrognathia. Mental retardation was seen in all patients. Verbal skills were better developed than motor skills. All patients in our study lead active lives, and most are involved in sports. Some hold supervised jobs. Eight of our patients live with their parents and two in group homes. Independent living is restricted by their mental and adaptive limitations.

Abnormalities, Multiple↗