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At least 253 records · Page 14Linked to original sources
PubMed1993

Laparoendoscopic upper pole partial nephrectomy with ureterectomy.

A 14-year-old white girl presented with a history of recurrent urinary tract infections beginning at age 18 months. Anatomical evaluation revealed bilateral duplication of the collecting systems. On the right side of the upper pole moiety ended at an obstructing orthotopic ureterocele. On the left side the upper pole moiety was associated with an ectopic ureteral orifice. The patient underwent laparoendoscopic right upper pole partial nephrectomy with ureterectomy. To our knowledge this is the first report of a laparoendoscopic upper pole partial nephrectomy. Details of the procedure are discussed.

Adolescent↗
PubMed1986

Ureteropelvic junction obstruction of the upper pole moiety in complete ureteral duplication.

Ureteropelvic junction obstruction of the upper pole moiety is reported in 2 patients with complete ureteral duplication. A normal upper pole ureter of a duplicated system in conjunction with upper pole dilatation should alert the urologist to the presence of an upper pole ureteropelvic junction obstruction. Traditional pyeloplasty techniques can be applied to this anomaly with successful salvage of renal parenchyma. The embryological implications of this combination of anomalies occurring in a single patient are discussed briefly.

Child↗
PubMed2002

Evidence that the Ipl1-Sli15 (Aurora kinase-INCENP) complex promotes chromosome bi-orientation by altering kinetochore-spindle pole connections.

How sister kinetochores attach to microtubules from opposite spindle poles during mitosis (bi-orientation) remains poorly understood. In yeast, the ortholog of the Aurora B-INCENP protein kinase complex (Ipl1-Sli15) may have a role in this crucial process, because it is necessary to prevent attachment of sister kinetochores to microtubules from the same spindle pole. We investigated IPL1 function in cells that cannot replicate their chromosomes but nevertheless duplicate their spindle pole bodies (SPBs). Kinetochores detach from old SPBs and reattach to old and new SPBs with equal frequency in IPL1+ cells, but remain attached to old SPBs in ipl1 mutants. This raises the possibility that Ipl1-Sli15 facilitates bi-orientation by promoting turnover of kinetochore-SPB connections until traction of sister kinetochores toward opposite spindle poles creates tension in the surrounding chromatin.

Aurora Kinases↗
PubMed1998

Quantitative detection of glaucomatous damage at the posterior pole by retinal thickness mapping. A pilot study.

OBJECTIVE: The posterior pole ganglion cell bodies form a substantial fraction of the retinal thickness, prompting the authors to study the feasibility of detecting, by scanning retinal thickness analysis, retinal changes at the posterior pole due to glaucomatous damage. STUDY DESIGN: Nonconsecutive case series. PARTICIPANTS: One or both eyes of patients with chronic open-angle glaucoma who presented with either a superoinferior asymmetry in visual fields or a localized field loss or a nerve fiber layer defect visible on photography were recruited. Twenty-nine eyes of 18 patients were studied. INTERVENTIONS: A laser slit was projected on the retina and scanned, in 400 msec, across a 2- x 2-mm area of the fundus, yielding optical cross-sections that were digitally recorded. Nine such scans covered the central 20 degrees of the fundus. The optical cross-sections were analyzed by an operator-free algorithm to yield a three-or two-dimensional color map. The asymmetry (difference) between the visual sensitivity of the upper and lower hemifields was compared with the asymmetry in retinal thickness deviation from normal. RESULTS: Large losses (up to 34%) in retinal thickness were detected at the posterior pole of patients with glaucoma due to the loss of ganglion cells and nerve fibers. A statistically significant correlation was found between the asymmetry in visual sensitivity loss and the asymmetry in deviation from normal thickness (r = 0.72; P < 0.0005). CONCLUSIONS: Mapping of the retinal thickness may provide a sensitive method for the detection and monitoring of early glaucomatous tissue loss in the posterior pole, which is unique due to the combination of (1) the direct measurement of neuroretinal loss in the central field of vision; (2) the mapping capability; and (3) the rapid image acquisition.

Adult↗
PubMed1999

Noninvasive mapping of the normal retinal thickness at the posterior pole.

OBJECTIVE: Objective and sensitive measurements of the retinal thickness at the posterior pole are useful to detect and delineate macular edema or retinal atrophy. The authors therefore developed an instrument, the Retinal Thickness Analyzer (RTA), to map the retinal thickness rapidly. The RTA was used to study the normal thickness at the posterior pole and to provide a pilot baseline. DESIGN: Cross-sectional study. METHODS: A green (540-nm) laser slit was focused on the retina via a scanning mirror placed at the conjugate plane of the pupil. The intersection between the laser slit and the retina was viewed at an angle and recorded by a video camera. Nine scans, each acquired in 200 to 400 msec, covered the central 20 degrees of the fundus. PARTICIPANTS: The posterior pole was mapped in 29 normal subjects 19 to 76 years of age (mean, 48 years). RESULTS: The thickness maps matched the posterior pole anatomy. Points with maximum thickness were located in the perifovea in a C-shaped manner extending from the disc to above and below the fovea. The local variation (standard deviation) in retinal thickness among the subjects was, on average, 15 microns. Age, gender, and race did not have a large effect (< 35 microns) on the values. CONCLUSIONS: Rapid scanning thickness analysis with the RTA provides a detailed map of the retinal thickness. The relatively narrow range of thickness values in normal subjects indicates that the method may provide a sensitive detection of pathologic thickening or thinning of the retina.

Adult↗
PubMed1989

Retrograde Herbert screw fixation for treatment of proximal pole scaphoid nonunions.

Most nonunions of the carpal scaphoid bone can be treated with a high rate of success by use of conventional bone grafting techniques. However, fractures with a small proximal pole fragment may be difficult to treat by use of these techniques. Nine patients with nonunion and three patients with unstable proximal pole fractures were treated with retrograde dorsal Herbert screw fixation and adjunctive bone grafting. Follow-up averaged 25 months. Of the 12 patients, the fracture healed in 11 and one fracture remained ununited. This technique has been successful in our practice and should be considered in the treatment of small proximal pole nonunions and displaced proximal pole fractures.

Adolescent↗
PubMed2003

Residual naming after damage to the left temporal pole: a PET activation study.

Normal subjects activate the left temporal polar cortex when they name persons, and subjects with damage to the left temporal pole due to left anterior temporal lobectomy are impaired in the retrieval of the proper names of persons. Eight such subjects were studied in a PET activation experiment to address the neural systems supporting their residual naming. We hypothesized that there would be increased activity, relative to normal controls, in the surround of the damaged region, the homologous right temporal pole, or both. Neither the group nor individual target subjects showed significantly increased activity in the lesion surround or in the right temporal pole. Several other regions that are activated by normals during the retrieval of the proper names of persons and which were undamaged in the target subjects (left anterior superior temporal sulcus, mesial frontal cortex, and anterior cingulate) were nevertheless significantly less activated by the target subjects, a finding that suggests that damage to the left temporal pole alters the function of a large-scale system needed for the retrieval of proper nouns. There was increased activity in early visual cortices, suggesting intensification of visual processing to compensate for the defective preferred name retrieval processing.

Adult↗
PubMed2002

Mitochondrial DNA variability in Poles and Russians.

Mitochondrial DNA (mtDNA) sequence variation was examined in Poles (from the Pomerania-Kujawy region; n = 436) and Russians (from three different regions of the European part of Russia; n = 201), for which the two hypervariable segments (HVS I and HVS II) and haplogroup-specific coding region sites were analyzed. The use of mtDNA coding region RFLP analysis made it possible to distinguish parallel mutations that occurred at particular sites in the HVS I and II regions during mtDNA evolution. In total, parallel mutations were identified at 73 nucleotide sites in HVS I (17.8%) and 31 sites in HVS II (7.73%). The classification of mitochondrial haplotypes revealed the presence of all major European haplogroups, which were characterized by similar patterns of distribution in Poles and Russians. An analysis of the distribution of the control region haplotypes did not reveal any specific combinations of unique mtDNA haplotypes and their subclusters that clearly distinguish both Poles and Russians from the neighbouring European populations. The only exception is a novel subcluster U4a within subhaplogroup U4, defined by a diagnostic mutation at nucleotide position 310 in HVS II. This subcluster was found in common predominantly between Poles and Russians (at a frequency of 2.3% and 2.0%, respectively) and may therefore have a central-eastern European origin.

DNA, Mitochondrial↗
PubMed2006

Single-molecule microscopy studies of electric-field poling in chromophore-polymer composite materials.

One strategy for increasing the efficiency of organic electrooptic devices based on chromophore-polymer composite materials is to improve chromophore ordering. In these materials, ordering is induced through the interaction of the chromophore dipole moment with an external electric field, applied at temperatures near the Tg of the polymer host, a process referred to as "poling". To provide insight into the molecular details of the poling process under conditions representative of device construction, the rotational dynamics of single 4-dicyano-methylene-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran (DCM) molecules in poly(methyl acrylate) at T = Tg + 11 degrees C in the presence and absence of an electric field are investigated using single-molecule confocal fluorescence microscopy. Single-molecule rotational dynamics are monitored through the time evolution of the fluorescence anisotropy. The anisotropy correlation function demonstrates nonexponential decay, with beta values derived from fits using the Kohlrausch-Williams-Watts law ranging from 0.7 to 1 with beta(KWW) = 0.83. This observation is consistent with previous studies of molecular rotation dynamics in polymer melts and reflects the dynamical heterogeneity provided by the polymer host. The rotational dynamics of DCM are weakly perturbed in the presence of a 50 V/microm electric field, typical of the field strength employed in device construction. The expected perturbation of the rotational dynamics is determined and found to be consistent with the alignment potential created by the electric field relative to the amount of thermal energy available. The relevance of these findings with respect to current models of the poling process is discussed. This work demonstrates the utility of polarization-sensitive single-molecule microscopy in elucidating the details of molecular reorientation during poling.

Journal Article↗
PubMed2002

Effect of poling conditions on growth of calcium phosphate crystal in ferroelectric BaTiO3 ceramics.

Recently, ceramic materials have been given a lot of attention as candidates for implant materials, since they possess biologically favorable characteristics for osseointegration. Among them, BaTiO3 (BTO) ceramics are ferroelectric and piezoelectric after poling treatments. However, little or no information is available on the poling condition of BTO and their effect on calcium phosphate (CaP) formation. In this study, the effect of poling conditions on the formation of CaP layer was investigated. It was observed from this study that CaP was formed on negatively charged BTO surfaces. An increase in Ca/P ratio to 1.67 was observed when the poling temperature was increased above the Curie temperature. On positively charged BTO, no CaP layer was observed.

Journal Article↗
PubMed1998

BMP regulates vegetal pole induction centres in early xenopus development.

BACKGROUND: Bone morphogenetic protein (BMP) plays an important role in mesoderm patterning in Xenopus. The ectopic expression of BMP-4 protein hyperventralizes embryos, whereas embryos expressing a BMP-2/4 dominant-negative receptor (DNR) are hyperdorsalized. Mesoderm is initially induced in the marginal zone by cells in the underlying vegetal pole. While much is known about BMP's expression and role in patterning the marginal zone, little is known about its early role in regulating vegetal mesoderm induction centre formation. RESULTS: The role of BMP in regulating formation of vegetal mesoderm inducing centres during early Xenopus development was examined. Ectopic BMP-4 expression in vegetal pole cells inhibited dorsal mesoderm induction but increased ventral mesoderm induction when recombined with animal cap ectoderm in Nieuwkoop explants. 32-cell embryos injected with BMP-4 RNA in the most vegetal blastomere tier were not hyperdorsalized by LiCl treatment. The ectopic expression of Smad or Mix.1 proteins in the vegetal pole also inhibited dorsal mesoderm induction in explants and embryos. Expression of the BMP 2/4 DNR in the vegetal pole increased dorsal mesoderm induction and inhibited ventral mesoderm induction in explants and embryos. CONCLUSIONS: These results support a role for BMP signalling in regulating ventral vegetal and dorsal vegetal mesoderm induction centre formation during early Xenopus development.

Animals↗
PubMed2003

A lytic transglycosylase homologue, PleA, is required for the assembly of pili and the flagellum at the Caulobacter crescentus cell pole.

Two distinct protein complexes, the flagellum and the pilus biogenesis machinery, are asymmetrically assembled at one pole of the Caulobacter predivisional cell. Cell division yields dissimilar daughter cells: a stalked cell and a swarmer cell that assembles several pili at the flagellated cell pole. Strains bearing mutations in the pleA gene are pililess and non-flagellated. The PleA protein contains a region that is similar to a peptidoglycan-hydrolytic active site, and a point mutation at this site in PleA results in the loss of flagellum and pili biogenesis. PleA was found to be required for the insertion of the outer membrane pilus secretion channel at the cell pole and for the accumulation of the PilA pilin subunit. PleA is also required for the assembly of substructures of the flagellar basal body hook complex that are located in or traverse the peptidoglycan layer. These results argue that PleA facilitates the assembly of envelope-spanning structures at the cell pole. In support of this, PleA was found to be present only during a short interval in the cell cycle that coincides with the assembly of the flagellum and the pilus secretion apparatus.

Amino Acid Sequence↗
PubMed1998

The incidence of lower-pole nephrolithiasis--increasing or not?

OBJECTIVE: To determine if the incidence of lower-pole nephrolithiasis is increasing. METHODS: A previously published meta-analysis of trends in the location of stones in the kidney, using data from 1984 to 1992, determined the percentage of lower pole stones in 26,722 kidney stones treated by extracorporeal shockwave lithotripsy (ESWL). We performed prospective studies on all patients treated by ESWL for a single renal stone (not manipulated from the ureter) in two organizations: at Lithotripters Inc., 47,303 stones were treated with ESWL by 1000 urologists in private practice from 1989 to 1995. At the Midwest Urologic Stone Unit, 9357 stones were treated with ESWL by 200 urologists in private practice from 1987 to 1995. The distribution of stones in both samples was compared with that reported earlier. RESULTS: The meta-analysis for stone location trends from the previously published article suggested that the percentage of kidney stones in the lower pole at ESWL increased erratically from 1984 to 1989 but was then stable for 3 years. The Lithotripters Inc. sample showed an essentially constant incidence from 28% in 1990 to 30% in 1995, and the Midwest Urologic Stone Unit sample showed an essentially constant incidence from 35% in 1988 to 36% in 1995. CONCLUSION: The incidence of lower pole nephrolithiasis has remained stable from 1990.

Humans↗
PubMed2003

The predictive value of diagnostic imaging for histological lesions of the upper poles in duplex systems with ureteroceles.

OBJECTIVE: To compare the diagnostic imaging findings with the histological lesions in upper pole nephrectomy (UPN) specimens of duplex system ureteroceles, using renal ultrasonography (US) and nuclear renal scintigraphy. PATIENTS AND METHODS: Between 1992 and 2000, 86 patients with a ureterocele in a duplex system underwent surgery. The results from US were reviewed in 84 patients by a radiologist, for echogenicity, parenchymal thinning and hydronephrosis; 77 nuclear renal scans describing the differential function of the upper poles were also reviewed. Fifty-five patients underwent UPN (25 antenatal, 30 postnatal; 18 intravesical, 37 extravesical) and the specimens were available for independent review by a pathologist, describing five histological categories, i.e. chronic interstitial inflammation, fibrosis, tubular atrophy, glomerulosclerosis and dysplasia. Histological lesions were categorized as severe (> 25%) or minimal (<or= 25%). Radiological features and the histology of UPN were then analysed, and correlated using Fisher's exact test and multivariate analysis. RESULTS: Severe histological lesions were reported in 38 specimens (69%) and minimal lesions in 17 UPN specimens (31%). Severe parenchymal thinning was associated with a severe pathological lesion (P < 0.02). There was no correlation with the echogenicity or degree of hydronephrosis. Dysplasia, found in 64% of specimens, did not correlate with increased echogenicity. Minimally functioning upper poles on nuclear renal scan (<or= 4% overall function) were significantly associated with severe histological lesions (P = 0.01). There was no correlation between diagnostic imaging features and the mode of presentation or type of ureterocele. CONCLUSIONS: Multivariate analysis, severe parenchymal thinning on renal US and minimal function on nuclear renal scan can be used to predict the severity of histological lesions of the upper pole. These results may be helpful in the making therapeutic decisions for patients with ureteroceles in duplex systems.

Adolescent↗
PubMed2000

Bipartite scaphoid with proximal pole osteonecrosis in a patient with Holt-Oram syndrome.

The Holt-Oram syndrome features a spectrum of upper limb abnormalities, including an abnormal shape of the scaphoid. Our report concerns a 19-year-old man with Holt-Oram syndrome and flattening and sclerosis of the proximal pole of a bipartite scaphoid. The initial ossification centre in the scaphoid was located distally at 8 years of age. By age 13, a pair of ossific centres were present. After an automobile accident at age 18, the proximal pole became sclerotic and then began to fragment over a 22-month period. Computed tomography confirmed the presence of two poles of the scaphoid and sclerosis and fragmentation of the proximal pole.

Adult↗
PubMed1998

Cycle rate variations in roller ski skating: effects on oxygen uptake and poling forces.

The purpose of this study was to examine the effect of cycle rate (CR) variations on the metabolic cost and upper body forces during roller skiing with the V2-alternate technique on flat terrain. Nine highly skilled cross-country skiers roller skied at a paced speed of 18.0+/-0.1 km x h(-1) using their chosen CR, and CRs that were 10% slower and 20% faster. Oxygen uptake (VO2) was determined through collection of expired gases into a meterological balloon and poling forces were measured with piezoelectric transducers during the last 30 s of each four minute trial of roller skiing. One-way repeated measures ANOVA revealed that VO2 varied significantly with CR (p=0.02) with the chosen CR being significantly lower than the higher CR (p < 0.05). Poling forces and poling time were not significantly different among the CR conditions. The present results demonstrate that 1) an alteration in cycle rate affects metabolic cost of roller ski skating, 2) skiers tend to naturally select the most economical cycle rate, and 3) moderate variations in cycle rate do not appear to affect propulsive force generation through the poles in roller skiing.

Adult↗
PubMed1975

Pole cells of Drosophila paulistorum: embryologic differentiation with symbionts.

The pole cells of young D. paulistorum embryos are destined to form the germinal cells of both male and female imagoes. In addition, specialized portions of the midgut may be derived from pole cell progenitors. In this initial study of their embryogenesis by means of electron microscopy, various stages of pole cell development are shown in both non-hybrid (potentially fertile) and intersemispecific hybrid (potentially sterile as males) materials. Originally, approximately 5 or 6 cells emerge to form the early polar cap and subsequently divide asynchronously until the 35-50 cells of the late polar cap are derived. Unlike other Drosophila species, however, mycoplasma-like symbionts, apparently an hereditary infection, have been traced to locations within the cytoplasm of these pole cells. They are depicted as arriving there after transmission via the egg cytoplasm, implicating this as their probable route of entry into the future germinal tissues of adult flies. It is postulated that these microorganisms function as an infectious reproductive isolating mechanism fostering hybrid male sterility between D. paulistorum semispecies.

Animals↗
PubMed1974

Transplantation of posterior polar plasm in Drosophila. Induction of germ cells at the anterior pole of the egg.

In Drosophila melanogaster the primordial germ cells are normally formed at the posterior tip of the egg during the preblastoderm stage. In order to determine whether the posterior polar plasm is capable of inducing the formation of primordial germ cells in another region of the embryo, portions of this cytoplasm were transferred from wild-type embryos of the early cleavage stage to the anterior tip of mwh e embryos of the same age. At various times after the injection (15-200 min), embryos were fixed for histological analysis. Alternating thick and thin sections were examined for the presence of experimentally induced pole cells. In more than half of the embryos analyzed in this way, one to six cells were found containing the polar granules as well as round nuclear structures, both of which are characteristic of normal pole cells and are not present in blastoderm cells. In order to determine whether these "pole cells" function normally, i.e., develop further into germ cells, the cells induced at the anterior tip of mwh e blastoderm embryos were introduced into the posterior region of y w sn(3) hosts of the same age. The flies resulting from these embryos were mated to y w sn(3) partners. In addition to the expected y w sn(3) progeny, wild-type flies heterozygous for mwh e and, therefore, descended from the experimentally induced pole cells were found in 4% of the crosses. Such flies did not appear in the control experiments after transfer of normal anterior cells from noninjected blastoderm embryos. These results demonstrate that the posterior polar plasm can be transferred to the anterior tip of the embryo and that in this presumptive somatic region it still retains its capacity to determine the formation of the primordial germ cells.

Animals↗