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PubMed2000

A comparative study of protein kinase C-like immunoreactive cells in the retina.

The present study is a morphological and quantitative analysis of protein kinase C-like immunoreactive (PKC-L ir) bipolar cells in the retinas of five different vertebrate species (chicken, tench, zebrafish, goldfish and rat). The morphology of PKC-L-ir bipolar cell axon terminals in fish differs significantly from those of chicken and rat retinas. Fish have bulky terminals whereas chicken and rat have their terminals in the form of small knob-shaped branches. In tench and goldfish, PKC-L-ir bipolar cells gradually decrease in size from the medial (i.e., in tench: mean +/- SD soma area of 30.09 +/- 5.98 microm2) to the peripheral (i.e., in tench: 19.93 +/- 1.73 microm2) retinal regions. This is not observed in chicken, rat or zebrafish where there is more homogeneity in s oma and axon terminal sizes between different retinal regions. Except in chicken, cell density increases from the central (i.e., in tench: mean +/- SD 1795.88 +/- 242.35 cells/mm2) to the peripheral (i.e., in tench: 4295.41 +/- 279.23 cells/mm2) retina. This study provides data that show relevant differences in the PKC-L-ir bipolar morphology and density among birds, fish and mammals. Moreover, these structural variations could mean not only differences in the cellular physiology, but also in the patterns of development and maintenance of the retina in each species.

Animals↗
PubMed2005

Identification and electrophysiological characteristics of isoforms of T-type calcium channel Ca(v)3.2 expressed in pregnant human uterus.

Electrophysiological characteristics were compared among four cloned human alpha1H isoforms transcripted by alternative splicings of exons 25B and 26 [Delta25B/+26 (native form; alpha1H-a), Delta25B/Delta?6 (alpha1H-b), +25B/Delta26, and +25B/+26] in the intracellular loop between domains III and IV (III-IV linker) of a human T-type calcium channel (Ca(v)3.2). The native isoform Delta25B/+26 predominated in ovary and non-pregnant uterus, while isoform Delta25B/Delta26 (alpha1H-b) predominated in pregnant uterus and testis. Expressions of the newly identified +25B/Delta26 and +25B/+26 isoforms were greater in the uterus at gestation than in the non-pregnant uterus. When expressed in Xenopus laevis oocytes, all isoforms produced transient inward currents with low voltage-dependent activation and inactivation characterized in typical T-type Ca2+ currents. Each isoform possessing exon 25B (+25B/?Delta26 or +25B/+26) showed current activation and inactivation at a more negative membrane potential than the respective isoform (Delta25B/Delta26 or Delta25B/+26) lacking it. Moreover, the current activation and inactivation rates were faster for the two isoforms possessing exon 25B than for the respective isoforms lacking it. By itself, exon 26 seemed not to affect any electrophysiological characteristics. Increasing the net positive charge (relative to the native form), as occurred in isoforms Delta25B/Delta26, +25B/Delta26, and +25B/+26, caused recovery from short-term inactivation to become faster. Our results show that molecular-structure variations within the III-IV linker influence the voltage-dependence and kinetics of both activation and inactivation. Although the role of T-type Ca2+ channels in uterine tissue remains unknown, changes in the uterine expression of these alpha1H isoforms may influence physiological functions during pregnancy.

Alternative Splicing↗
PubMed2006

The role of protein glycosylation in allergy.

The asparagine-linked carbohydrate moieties of plant and insect glycoproteins are the most abundant environmental immune determinants. They are the structural basis of what is known as cross-reactive carbohydrate determinants (CCDs). Despite some structural variation, the two main motifs are the xylose and the core-3-linked fucose, which form the essential part of two independent epitopes. Plants contain both epitopes, insect glycoproteins only fucose. These epitopes and other fucosylated determinants are also found in helminth parasites where they exert remarkable immunomodulatory effects. About 20% or more of allergic patients generate specific anti-glycan IgE, which is often accompanied by IgG. Even though antibody-binding glycoproteins are widespread in pollens, foods and insect venoms, CCDs do not appear to cause clinical symptoms in most, if not all patients. When IgE binding is solely due to CCDs, a glycoprotein allergen thus can be rated as clinical irrelevant allergen. Low binding affinity between IgE and plant N-glycans now drops out as a plausible explanation for the benign nature of CCDs. This rather may result from blocking antibodies induced by an incidental 'immune therapy' ('glyco-specific immune therapy') exerted by everyday contact with plant materials, e.g. fruits or vegetables. The need to detect and suppress anti-CCD IgE without interference from peptide epitopes can be best met by artificial glycoprotein allergens. Hydroxyproline-linked arabinose (single beta-arabinofuranosyl residues) has been identified as a new IgE-binding carbohydrate epitope in the major mugwort allergen. However, currently the occurrence of this O-glycan determinant appears to be rather restricted.

Allergens↗
PubMed1994

Molecular cytogenetic characterization of two types of chromosome 9 variants.

Structural variations in the pericentromeric region of chromosome 9 are common. Molecular cytogenetic characterization of two types of rare variants, each studied in two families, are reported. For convenience, the variants are designated as types 2 and 3. Type 2 variants contain an additional G-positive band in the short arm near the centromere. Type 3 variants have heterochromatin both above and below the centromere in addition to having an additional G-positive band in the short arm immediately distal to the heterochromatin. Fluorescence in situ hybridization using alpha-satellite and D9Z5 beta-satellite probes revealed two clear hybridization signals in type 3 variants, one corresponding to the position of the centromere and the other to the position of the additional G-positive band. Results of type 2 variants are less conclusive, probably due to the close proximity of the additional band to the centromere, but are suggestive of additional hybridization in proximal 9p. Our finding suggests that the type 3 variant, and possibly the type 2 variant, may represent dicentric chromosomes that are functionally stable and phenotypically inconsequential.

Chromosome Banding↗
PubMed1976

Correlation between the structure of the wall of the bone lacuna and the localization of the osteocyte within this lacuna. Electron-microscopic studies.

A correlation between the structure of the wall of the bone lacuna and the localization of the osteocyte within this lacuna was the object of investigation under light and electron microscopes. On the basis of the structural divergences detected, the author distinguished zones A and B in the osteocyte situated in the lacuna. Zone B is characterized by a parallel, compact system of collagen fibrils which form a characteristic ridge in the lacunar wall, a continuous demarcating line bordering this wall, the osteocyte cytoplasm in this part lying far from the lacuna wall and surrounding the nucleus with a narrow band, and the pericellular space which is wide here and containing a large number of mucopolysaccharides. This picture may correspond to the area of temporary non-reactivity of the osteocyte. Zone A is characterized by a loosened and disordered system of collagen fibrils forming the lacunar wall. These fibrils being exposed in this place by nature, the demarcating line bordering the lacunar wall is broken in some places, the osteocyte cytoplasm is considerably concentrated around the nucleus and contains a large number of organelles. It also lies closer to the lacunar wall, which results in a decreased width of the pericellular space and a diminished mucopolysaccharide content in this part of the lacuna. Structural variations in the lacuna wall and its space (zones A and B) observed in the images obtained with a normal bone in the light and electron microscopes show their immediate dependence on the position of the osteocyte in the lacuna, which may be associated with the osteocyte activity. On the other hand, the occurrence of significant changes in a definite zone (zone A) of the lacuna only points to the oriented character of this activity.

Animals↗
PubMed1993

Cementum-like tissue deposition on the resorbed pulp chamber wall of human deciduous teeth prior to shedding.

In the later stage of exfoliation in human deciduous teeth, odontoclastic resorption takes place at the pulpal surface of the coronal dentin. However, this resorption does not continue until the teeth are shed, and the resorbed pulp chamber wall is usually repaired by cementum-like tissue deposition. In this study, we examined the formation and characteristics of the cementum-like hard tissue on the resorbed dentin surface in the pulp chamber of deciduous teeth prior to shedding. The site and degree of deposition of newly formed cementum-like tissue on the resorbed pulp chamber wall varied from tooth to tooth. Furthermore, they also showed compositional and structural variations. Generally, however, the matrix of the cementum-like tissue was composed of intrinsic collagen fibers, acellular or cellular. There was a tendency for acellular cementum-like tissue to be deposited on small and shallow resorption bays, whereas the cellular type was found on larger and deeper ones. In both cases, the surface of the deposited cementum-like tissue on the resorbed dentin surface usually became flat. However, unlike the cementum repair of resorbed areas on the root surface, no acellular extrinsic fiber cementum-like tissue was found on the resorption pulp chamber wall. Although the role of the repair of the resorbed pulp chamber wall with cementum-like tissue deposition just before shedding is unknown, it might play some role in the retention of deciduous teeth until shedding.

Dental Pulp↗
PubMed1990

Genetic studies of human apolipoproteins. XV. An overview of IEF immunoblotting methods to screen apolipoprotein polymorphisms.

Genetically determined structural variation in the gene products of various apolipoproteins plays a significant role in modulating lipid levels in the population at large. However, due to tedious and cumbersome experimental problems involved, the detailed characterization of this genetic variation has been limited. The recent development of simple and sensitive isoelectric focusing and immunoblotting methods has circumvented these technically associated problems to a large extent, and this has allowed us to expand the genetic data on various apolipoproteins to previously uncharacterized populations. We have reviewed here these isoelectric focusing and immunoblotting methods. A comprehensive listing of allele frequencies has also been given for the polymorphic apolipoproteins.

Apolipoproteins↗
PubMed1985

Vocal communication in lion-tailed macaques (Macaca silenus).

Investigations of vocal communication in captive groups of lion-tailed macaques (Macaca silenus) revealed a repertoire of 17 basic patterns. Sixteen of them were recorded and their physical parameters analysed by sonagrams. During a field study these results were verified and complemented, and additional data on the vocal behaviour of this species were gathered. The vocal repertoire of lion-tailed macaques is characterized by discretely structured, mostly interaction- and situation-specific sound patterns. The fundamental characteristics of vocal communication seem to be adjusted to the acoustic conditions of the rain forest habitat as well as to the social organization in 1-male groups. In contrast to other species of the macaque genus, lion-tailed macaques are highly adapted to a strictly arboreal life in the rain forests of the Western Ghats (South India). Due to the dense vegetation in this habitat, propagation of visual signals is restricted to short distances. Vocal signals are therefore of great importance. The vocal repertoire of lion-tailed macaques differs from that of more terrestrial macaques insofar as the basic patterns show comparatively insignificant structural variations. Also, patterns were recorded which have not yet been found in any other member of the genus.

Animals↗
PubMed1989

Genetic studies of low-abundance human plasma proteins. XI. Linkage analysis and population genetics of the C1S subcomponent of the first complement component.

Although subcomponents C1r and C1s of the first complement component, C1, have been established to be in the same linkage group as the proline-rich protein gene cluster on chromosome 12p13.2, no direct analysis of linkage between the C1R and C1S structural gene loci has been available. We have detected through a population screening study 5 families which are heterozygous at the structural loci for both C1R and C1S. Three of the 5 families, 21 individuals, were informative for linkage. A maximum lod score of 1.505 at theta = 0.00 was found in a two-point analysis between C1R and C1S. Ten populations were screened for structural variation at the C1S locus. Only US Whites and a Kodiak Island Eskimo group expressed heterogeneity. The frequencies of the designated alleles, C1S*1 and C1S*2, were 0.992 and 0.007, respectively, in the US White population and 0.998 and 0.002, respectively, in the Kodiak Island Eskimo population. In addition, the product of a putative new allele, designated C1S*4, was observed in a single US White individual but segregation of this variant was not observed in the limited family data available.

Blood Proteins↗
PubMed1993

Hepatic lipase deficiency. Clinical, biochemical, and molecular genetic characteristics.

Hepatic lipase (HL) is an important enzyme in the metabolism of triglyceride-rich lipoproteins and high density lipoproteins. The clinical syndrome of HL deficiency is rare and difficult to identify. We studied carriers of mutant HL to ascertain whether there are distinctive clinical and/or biochemical characteristics of the heterozygous state. In an Ontario kindred, compound heterozygosity for two HL mutations, S267F and T383M, underlies the clinical syndrome of complete HL deficiency. We report that simple heterozygotes for either HL mutant do not have a discrete lipoprotein abnormality, except for relative triglyceride enrichment of lipoprotein fractions with d > 1.006 g/mL. Postheparin HL activity is depressed to a greater degree in carriers of S267F compared with carriers of T383M. Retinyl palmitate loading studies in a compound heterozygote revealed impaired clearance of chylomicron remnants. The dyslipoproteinemia in a compound heterozygote was ameliorated by lovastatin. There was no difference in the quantity and distribution of HL mRNA in the liver of a compound heterozygote when compared with that of a normal subject. Thus, HL deficiency associated with structural variation of the HL gene is characterized by premature atherosclerosis, triglyceride enrichment of lipoprotein fractions with d > 1.006 g/mL, the presence of circulating beta-very low density lipoproteins, and abnormal catabolism of postprandial triglyceride-rich lipoproteins.

Adult↗
PubMed2001

The relationship between craniofacial morphology and obstructive sleep apnea in whites and in African-Americans.

Previous studies of craniofacial risk factors for obstructive sleep apnea (OSA) have been based predominantly on cephalometry. However, differences in head form (measured by the cranial index [CI]) and facial form (measured by the facial index [FI]) are considered by anthropologists to provide a basis for structural variation in craniofacial anatomy. We assessed the association of head and facial form with the apnea hypopnea index (AHI) in 364 white individuals and 165 African-Americans. Data collected included cranial and facial dimensions (using anthropometric calipers), body mass index (BMI), neck circumference, and the AHI. CI and FI differed for whites with OSA (AHI > or = 15) versus those without OSA (AHI < 5) (increased CI and decreased FI in subjects with OSA, p = 0.005 and p = 0.006, respectively). CI and FI did not differ in OSA versus non-OSA groups of African-Americans. In subjects with OSA, the CI in whites was again greater and the FI smaller than those in African-Americans (p = 0.007 and p = 0.004, for CI and FI.) We conclude that brachycephaly is associated with an increased AHI in whites but not in African-Americans. The CI may useful in phenotyping and identifying population subsets with OSA.

Adult↗
PubMed1983

Genetic polymorphism in C8 beta-chains. Evidence for two unlinked genetic loci for the eighth component of human complement (C8).

Genetic polymorphism in the beta-subunit of the eighth component of human complement, C8, was defined by isoelectric focusing of serum in polyacrylamide gel in the presence of urea and development of specific patterns of hemolysis in an overlay gel containing antibody-sensitized erythrocytes and C8 beta-chain-deficient serum. Bands of hemolysis induced by serum from unrelated Caucasians suggested autosomal codominant inheritance of three structural alleles at a single locus, C82: C82 degrees A (acidic), C82 degrees B (basic), and C82 degrees A1 (very acidic) with frequencies of 0.952, 0.044, and 0.004, as well as the probable null allele C82 degrees Q0. The distribution of phenotypes agreed with the Hardy-Weinberg equilibrium. The previously described genetic polymorphism in human C8 defined with the use of "complete" C8 (C8 alpha-gamma-chain)-deficient serum was distinct from and independent of the inherited structural variation at C82. Therefore, the locus for C8 alpha-gamma-chains has been redesignated C81, and has the alleles C81 degrees A, C81 degrees A1, and C81 Q0. Linkage studies failed to show close linkage between the two loci for C8, C81, and C82, and between C82 and the major histocompatibility complex or C6.

Alleles↗
PubMed1989

Apolipoprotein A-I variants. Naturally occurring substitutions of proline residues affect plasma concentration of apolipoprotein A-I.

Six unrelated families with genetically determined structural variants of apo A-I were found in the course of an electrophoretic screening program for apo A-I variants in dried blood samples of newborns. The following structural variations were identified by the combined use of HPLC, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and automated gas phase sequencing: Pro3----Arg (1x), Pro4----Arg (1x), and Pro165----Arg (4x). All variant carriers were heterozygous for their mutant of apo A-I. Subjects heterozygous for apo A-I(Pro165----Arg) (n = 12) were found to exhibit lower mean values for apo A-I (109 +/- 16 mg/dl) and HDL cholesterol (37 +/- 9 mg/dl) than unaffected family members (n = 9): 176 +/- 41 and 64 +/- 18 mg/dl, respectively (P less than 0.001). In 9 of 12 apo A-I(Pro165----Arg) variant carriers the concentrations of apo A-I were below the fifth percentile of sex-matched controls. By two-dimensional immunoelectrophoresis as well as by densitometry the relative concentration of the variant apo A-I in heterozygous carriers of apo A-I(Pro165----Arg) was determined to account for only 30% of the total plasma apo A-I mass instead of the expected 50%. Thus, the observed apo A-I deficiency may be largely a consequence of the decreased concentration of the variant apo A-I. In the case of the apo A-I(Pro3----Arg) mutant, densitometry of HDL apolipoproteins demonstrated a distinctly increased concentration of the variant proapo A-I relative to normal proapo A-I. This phenomenon was not observed in the apo A-I(Pro4----Arg) mutant or in other mutants. This suggests that the interspecies conserved proline residue in position 3 of mature apo A-I is functionally important for the regular enzymatic conversion of proapo A-I to mature apo A-I.

Amino Acid Sequence↗
PubMedDate not supplied

Anatomy of the round window niche.

The contributing elements to boundaries of the round window niche are superiorly the tegmen fossula fenestra rotunda (roof support), inferiorly the fustis (depth) and area concamerata, anteriorly the sustentaculum (support) and postis anterior (anterior pillar), and posteriorly the postis posterior (posterior pillar) and the subiculum (underlying supporting structure). Variations in their size and orientation can give rise to significant variability in the overall size and shape of the round window niche.

Cochlea↗
PubMed1993

On monitoring structural changes of anisotropic tissues by means of statistical analysis of ultrasonic images.

An investigation into statistical properties of ultrasonic image texture from three-dimensional clusters of anisotropic scatterers is carried out. The structural properties of the clusters are modeled after those of soft biological tissues, such as skeletal muscle tissues, both in their healthy condition and at the early stage of degenerative diseases. The average axial autocorrelation function of the intensity of the image texture is used to characterize and monitor changes of the geometrical properties of the tissue components. A distinct local increase of the autocorrelation is observed within a range of small time shifts, and it is explained in terms of the structure of the time-domain backscattered signal from each individual scatterer. It is shown that such an increase is sensitive to structural variations of the cluster similar to those occurring at the early stage of several muscular diseases.

Anisotropy↗
PubMed1988

Softening of thermoplastic polyurethanes: a structure/property study.

Softening of thermoplastic polyurethanes (TPU) in a simulated body environment (37 degrees C n-saline) was studied as a function of composition, structure and resultant morphology of these (AB)n type block copolymers. The structural variations were attempted by changing chemical composition and molecular weight of both hard A and soft B segments and their weight ratio in the polymer. In addition, the influence of bulk and/or surface modifiers, such as "reacted-in" polysiloxanes and fluorinated polyalkylether glycols, was also investigated. The degree of softening, expressed as a percentage decrease of the elastic modulus (5% tensile modulus) upon two hours exposure to the testing environment, is significant, reversible and depends on the ratio of hard to soft segment and the extent of microphase separation. Since these parameters can be selected during the polymer synthesis and processing into desirable shapes, the degree of softening can thus be controlled. This softening at body temperature represents one of the most notable performance advantages of these biomaterials.

Elasticity↗
PubMed2006

Collagen fiber architecture of the periodontal ligament in equine cheek teeth.

The objective of this study was to examine the spatial arrangement of the fiber apparatus of the equine periodontium which is supposed to meet two contrary requirements: (1) to attach the tooth firmly and elastically to the alveolar bone; and, to be appropriately remodeled and reconstructed in order to facilitate the prolonged eruption of the tooth. Specimens of periodontal ligament were obtained from the buccal and lingual/palatal aspects of the first molars from the maxilla and mandible of 12 horses. The animals were assigned to three age groups. Histological sections were prepared from three specific horizontal levels of the periodontal ligament and examined with conventional and polarized-light microscopy. At the gingival level, collagen fascicles (diameter > 200 microm) were densely packed. Their spatial alignment was the same in all age groups. The architecture of the collagen fiber apparatus differed at the middle and apical levels in the three age groups. There was a clear distinction between fibers, bundles, and fascicles. Bundling of collagen fibers, density of the fiber arrangement, and collagen fascicles with an alveolo-cemental orientation increased with age. The collagen fiber apparatus of the equine periodontal ligament is highly adaptive, responding continuously to the dynamic changes in the periodontal environment. Site-specific arrangements and age-dependent structural variations are assumed to maintain tooth support as the reserve crown gradually decreases in length with progressive dental attrition. Most of the age-dependent changes to the periodontal ligament in teeth examined in this study occurred at the apical level. The apical region of young teeth had no periodontal attachment, while the roots of older teeth were firmly attached to the alveolus. When evaluating periodontal ligament development, the individual tooth's 'dental age' should be considered rather than the animal's age to account for individual tooth eruption times.

Age Factors↗
PubMed2000

Indicator-based systems of performance management in the National Health Service: a comparison of the perceptions of local- and national-level managers.

Historically, the UK Government has policed the use of National Health Service (NHS) resources through the centralization of control. With the majority of resource-draining decisions being taken by clinicians, however, professional financial accountability is becoming more important within the NHS management structure. Variations in clinical performance can be monitored through the use of performance indicators, although these are not without their problems. The use of league tables of such indicators in the national press is now infamous and there is much anecdotal evidence about the intraorganizational conflict arising from the use of such tables. A questionnaire survey and interview study of clinical directors, clinical service directors and business managers in several Scottish NHS Trusts was undertaken to ascertain the perceptions of local-level managers on the issue of performance indicators. Interviews were also carried out with a number of personnel in the Scottish Office Department of Economics and Information, the Division of Health Gain and the Finance Directorate. This paper explores the differences between the perceptions of the managers at these two levels of the NHS with regards to issues of performance measurement, intraorganizational conflict and corporate vision.

Administrative Personnel↗