Sonographic detection of a small-bowel bezoar.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
S R Wilson
Publications and source records attributed to S R Wilson.
Accommodating change due to treatment in the method of back projection for estimating HIV infection incidence.
This note shows how the method of back projection, which is being widely applied to predict the incidence of HIV infection, can be extended to incorporate distributional changes due to a treatment effect, such as zidovudine (commonly known as AZT). By way of example we consider one of the approaches to back projection and apply the method to some Australian data.
Acquired Immunodeficiency Syndrome↗
Genetic counseling in rare syndromes: a resampling method for determining an approximate confidence interval for gene location with linkage data from a single pedigree.
Multipoint linkage analysis is a powerful method for mapping a rare disease gene on the human gene map despite limited genotype and pedigree data. However, there is no standard procedure for determining a confidence interval for gene location by using multipoint linkage analysis. A genetic counselor needs to know the confidence interval for gene location in order to determine the uncertainty of risk estimates provided to a consultant on the basis of DNA studies. We describe a resampling, or "bootstrap," method for deriving an approximate confidence interval for gene location on the basis of data from a single pedigree. This method was used to define an approximate confidence interval for the location of a gene causing nonsyndromal X-linked mental retardation in a single pedigree. The approach seemed robust in that similar confidence intervals were derived by using different resampling protocols. Quantitative bounds for the confidence interval were dependent on the genetic map chosen. Once an approximate confidence interval for gene location was determined for this pedigree, it was possible to use multipoint risk analysis to estimate risk intervals for women of unknown carrier status. Despite the limited genotype data, the combination of the resampling method and multipoint risk analysis had a dramatic impact on the genetic advice available to consultants.
Chromosome Mapping↗
Structure of 3-isoinosine.
3-beta-D-Ribofuranosylhypoxanthine, 3-beta-D-ribofuranosyl-1,6-dihydro-3H-purin-6-one, C10H12-N4O5, Mr = 268.23, monoclinic, P2(1), a = 6.503 (1), b = 24.007 (6), c = 7.392 (2) A, beta = 106.53 (2) degrees, V = 1106.3 (9) A3, Z = 4, Dx = 1.610 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.23 cm-1, F(000) = 560, T = 299 K, R = 0.048 and wR = 0.043 for 1602 observed reflections. There are two crystallographically independent molecules in the structure; in both of them the 6-oxo, 7H tautomer is the predominant form. The bond lengths and angles of the two molecules are almost identical and the hypoxanthine moiety is almost planar. The torsional angles of the glycosidic linkage O(4')-C(1')-N(3)-C(4) are -159.3 and -148.8 degrees, both in the anti range. The sugar puckers are 4T3 (C4'-exo/C3'-endo), with P = 46.35 degrees and tau m = 42.30 degrees, and 2E (C2'-endo), with P = 157.24 degrees and tau m = 41.32 degrees. All N and O atoms except N(3) and O(4') participate in a three-dimensional hydrogen-bonding system.
Chemical Phenomena↗
Multivariate analysis of body shape in fragile X (Martin-Bell) syndrome.
Human body shape measures can be more informative in studies of developmental abnormalities than distances between body landmarks. Such measures were obtained by an appropriate transformation of 34 distances between trunk/limbs and head/face landmarks in 43 men and 72 women with the Martin-Bell Syndrome (MBS), and in 99 and 103 normal men and women, respectively. The transformation of the original distances was performed by adjusting individual measures for an overall size measure using regression analysis. Thus obtained body shape variables were used in discriminant analysis in order to obtain unbiased classification probabilities of individuals having the MBS or being normal. The average percent correctly classified male and female individuals was high (93 and 87, respectively). Moreover, the body shape variables were used to obtain shape dimensions by means of principal component analysis. There was no difference between the MBS and normal individuals in the first (most important) principal component (shape dimension). This component represents the relative proportions between trunk and limb lengths and widths, or between midfacial lengths and widths. However, there were appreciable differences in some succeeding components. The problem of interpretation of shape dimensions as derived from principal component analysis and of their relevance to abnormal development in the MBS individuals is discussed.
Adolescent↗
Summary measures for evaluating the evidence for linkage.
Two summary measures for evaluating the evidence for linkage are the maximum lod score and the average of the likelihood function (antilod score). The average antilod score can be used to calculate an exact probability of there being no linkage. Use of subjective prior probabilities in the calculation will only influence the final conclusion in any important way if evidence from the sample is not particularly conclusive. It is shown how results from two-point analyses for linkage of the test locus with each marker locus can be easily combined to give an approximate probability of there being no linkage. Some examples using bipolar affective disorder data and marker loci are presented.
Bipolar Disorder↗
Patrick A.P. Moran, 1917-1988: in memoriam.
Explore the source record for details and available documents.
Australia↗
Ultrasonic characterization of selected renal tissues.
Velocity, attenuation, and backscatter of ultrasound were measured in human renal tissues over a frequency range relevant to clinical imaging (3.5-7 MHz). Normal renal tissues, as well as three types of mass (angiomyolipoma, renal cell carcinoma, and oncocytoma) were studied, and comparisons made of the appearance of the tissues in clinical images to their ultrasonic and pathological properties. The results showed angiomyolipoma had high attenuation and backscatter coefficients due to acoustic impedance differences between fat and smooth muscle components of the tumour. The renal cell carcinomas were indistinguishable from normal kidney tissue, except in one case where infiltration by fatlike macrophages led to high attenuation and backscatter coefficients. This finding also supports the conclusion that fat/nonfat interfaces are a dominant scatter mechanism in renal tissues.
Adenoma↗
2-Arylindenes and 2-arylindenones: molecular structures and considerations in the binding orientation of unsymmetrical nonsteroidal ligands to the estrogen receptor.
We have studied how 2-arylindene systems, unsymmetrical nonsteroidal estrogens, orient themselves within the binding site of the estrogen receptor, relative to estradiol, by making a comprehensive comparison of the binding affinity of 16 analogues. These analogues are representatives of two major classes, those substituted at C-3 with an ethyl or with a phenyl substituent; within each class there are members that have different patterns of hydroxyl group substitution and C-1 oxo or alkyl substitution. Orientational preferences were inferred from the relative binding affinities and were supplemented by computer graphic molecular overlap studies that utilized crystal structures of selected representative compounds and the known tolerance of the estrogen receptor to substituents on the steroidal ligand estradiol. 2-Arylindenes with a 3-aryl substituent appear to orient with the indene system mimicking the A- and B-rings of estradiol (indene/AB mode). This orientation is supported by the fact that hydroxyl substitution at C-6 in the indene markedly elevates binding relative to hydroxyl substitution at the para position of the 2-phenyl substituent. A C-1 oxo substituent increases binding further, but a C-1 alkyl group has little effect. By contrast, the 2-arylindenes with a C-3 ethyl substituent appear to bind with the pendant C-2 ring, mimicking the A-ring of estradiol (pendant/A mode), as hydroxyl substitution in this ring elevates binding relative to the C-6 hydroxy analogues. C-1 alkyl substitution elevates binding affinity in this series; such a substituent in a C-1 S configuration would be projected into the receptor region normally occupied by the high-affinity 7 alpha- or 11 beta-alkyl estradiols. A C-1 oxo substituent produces only a modest binding enhancement in the C-3 ethyl series. A thermodynamic evaluation of receptor fit suggests that the smaller 3-ethyl-2-arylindenes are more efficient than the 2,3-diarylindenes in the use of the molecular bulk to achieve receptor binding. This analysis of the orientational preference of 2-arylindene nonsteroidal estrogens has important implications in the design of donor/acceptor-substituted 2-arylindenes as fluorescent ligands for the estrogen receptor.
Animals↗
The synthesis of glutathione peroxidase analogs.
While it is recognized that oxidation has a major role in the development of cataract, few compounds have been developed which effectively reduce the potential for oxidative insult. A major oxidant confronting the lens is H2O2. Few compounds capable of metabolizing H2O2 have been synthesized. This communication reports that a number of compounds with glutathione peroxidase activity have been developed. Some of these compounds are 10 fold more active than Ebselen, previously recognized as the synthetic compound with the greatest GSH peroxidase activity.
Azoles↗
Multipoint linkage: statistical evaluation.
Explore the source record for details and available documents.
Chromosome Mapping↗
Ultrasonography of splenic variants.
We report seven patients in whom unusual left upper quadrant abdominal masses were found on ultrasonography (US) and subsequently proven to be splenic variants. In five patients, a round discrete mass was present in the left suprarenal area, separate from a spleen which appeared to be normal. A sixth patient had multiple masses in the splenic region and a postsplenectomy seventh patient had a left posterior, para-aortic mass at the level of the renal hilum. Computed tomography (CT) confirmed the presence of the mass in four patients. In two, the mass was biopsied. Confirmatory radionuclide liver and spleen scans were performed in six patients. Single-photon emission CT proved to be most specific by demonstrating functioning splenic tissue in the region of the masses. Knowledge of the normal anatomy and embryology of the spleen readily explains the findings in our patients. Splenic variants should be considered in the differential diagnosis of problematic, left upper quadrant masses seen on US.
Adult↗
Cholesterol metabolism. Effect of 26-thiacholesterol and 26-aminocholesterol, analogues of 26-hydroxycholesterol, on cholesterol synthesis and low-density-lipoprotein-receptor binding.
1. The effects of 26-aminocholesterol and 26-thiacholesterol on cholesterol synthesis and LDL (low-density lipoprotein)-receptor activity were compared with naturally occurring 26-hydroxycholesterol utilizing both human fibroblasts and hepatoma (Hep G2) cells. 2. At equimolar concentrations (0.625 microM), down-regulation of LDL-receptor activity and cholesterol synthesis was greater with human fibroblasts than with Hep G2 cells. 3. At much higher concentrations (5-20 microM) the 26-thia analogue had little effect on either cholesterol synthesis or LDL-receptor activity.
Animals↗
Structure of 3-isoadenosine.
3-beta-D-Ribofuranosyladenine, C10H13N5O4, Mr = 267.25, orthorhombic, P2(1)2(1)2(1), a = 13.470 (4), b = 16.054 (6), c = 5.141 (2) A, V = 1111.8 (7) A3, Z = 4, Dx = 1.596 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.18 cm-1, F(000) = 560, T = 298 K, R = 0.043, wR = 0.042 for 1136 reflections. The tautomeric form present in the crystal is 6-NH2. The adenine moiety is nearly planar and the torsional angle of the glycosidic linkage O(4')-C(1')-N(3)-C(4) is -161.5 degrees. All N and O atoms except N(3) and O(4') participate in a three-dimensional hydrogen-bonding system.
Adenosine↗
A major simplification in the preliminary ordering of linked loci.
For ordering n loci there are n!/2 distinct orders to be evaluated. Each order has a different set of event probabilities where the events are the occurrence and nonoccurrence of recombination in each interval determined by that order. To choose between the distinct orders, further assumptions are necessary. The biologically natural one is that the recombination rate over a subinterval is always less than or equal to the recombination rate over the larger interval. A second assumption is necessary, and the one commonly made is that there is no interference. Using a simple matrix approach it is shown that a consequence of these assumptions is that the optimal order is the order with the minimum value of the product of the adjoining pairwise recombination rates. This result gives a very simple procedure for obtaining preliminary genetic maps that may be used as starting points for more computer-intensive, maximum-likelihood, multipoint techniques.
Chromosome Mapping↗
2,3-Diarylindenes and 2,3-diarylindenones: synthesis, molecular structure, photochemistry, estrogen receptor binding affinity, and comparisons with related triarylethylenes.
Two 2,3-diphenylindene and -indenone systems, with potential fluorescent and photofluorogenic properties, were prepared and studied as ligands for the estrogen receptor. The indene systems were prepared by Friedel-Crafts cyclization of appropriate alpha-benzyl desoxybenzoin systems, and the indenones either by oxidation of the indenes, by cyclization of alpha-benzoyl desoxybenzoins, or by acylium ion attack on tolan. Crystallographic analysis of the 2,3-diphenylindene and -indenone systems shows the phenyl substituents twisted out of the plane of the indene/indenone systems, with both torsional angles greater in the indenone than indene system; the phenyl attachment to the five-membered ring allows these systems to be considerably more planar than the related 1,2-diphenyl-3,4-dihydronaphthalene and the triarylethylene nonsteroidal estrogens. In contrast to the diphenyldihydronaphthalenes, the diarylindene and -indenone systems undergo photocyclization to phenanthrenes inefficiently. The estrogen receptor binding affinity of these systems is reasonably high (9-59% relative to estradiol), with the indenone systems having higher affinity than the indenes; additional hydroxyl substitution raises the affinity of the indenes but lowers that of the indenones. These trends can be rationalized by considering differences in molecular volumes or surface areas (related to torsional angles) and specific polar interactions.
Binding, Competitive↗
Selection affecting enzyme polymorphisms in enclosed Drosophila populations maintained in a natural environment.
Allele frequencies for the Adh, Gpdh, and Est6 enzyme polymorphisms of Drosophila melanogaster show large-scale latitudinal clines, whereas those for Pgm do not vary systematically with latitude. To elucidate possible mechanisms of selection underlying these distributions, large collections of the species were made from five Australasian localities spanning 24 degrees of latitude. Two replicate experimental populations were established from each collection, and each replicate was then released into an enclosure surrounding a natural habitat at a central-latitude locality. Genotype frequencies at the four loci were monitored for 15 months, covering 12 discrete generations, and selection coefficients on each polymorphism were then estimated by maximum likelihood procedures. For Est6 no coefficients were found to be significantly different from zero. For Pgm some nonzero coefficients were estimated, but these were heterogeneous across experimental populations of different geographic origins. For both Adh and Gpdh, nonzero selection coefficients were estimated that were homogeneous across populations and indicated heterozygote advantage. Predicted Adh and Gpdh equilibrium allele frequencies were consistent with those found in adjacent free-living populations. It is concluded that, at such intermediate latitudes at least, selection operates on the Adh and Gpdh polymorphisms to the advantage of heterozygotes.
Alcohol Dehydrogenase↗
Pancreatic neoplasms: how useful is evaluation with US?
The usefulness of ultrasonography (US) in the evaluation of pancreatic neoplasms was assessed in 51 patients. Indications for US included jaundice (n = 19), pain (n = 16), weight loss and anorexia (n = 4), clinically palpable mass (n = 3), bleeding in the upper gastrointestinal tract (n = 1), and gastric outlet obstruction (n = 1). Three patients were investigated because of a previous abnormal US examination; in four the mass was an incidental observation. Sonograms were interpreted without knowledge of results from other procedures. Pancreatic masses were detected in 50 patients. Biliary and pancreatic duct obstructions were seen in 29 and 27 patients, respectively. Liver metastases were identified in 16 patients and missed in three that were not detected with either US or computed tomography. Vascular involvement was predicted in 12 patients and missed in four, while lymphadenopathy was seen in 16 and missed in five. Thirty-one cases of unresectable disease were correctly predicted with US. Resectability was not as accurately determined; only seven of 19 "resectable" lesions were successfully removed. US is an effective tool in the detection and preoperative evaluation of pancreatic malignancy.
Adult↗