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At least 235 records · Page 13Linked to original sources
PubMed2005

Pelvi-calyceal height, a predictor of success when treating lower pole stones with extracorporeal shockwave lithotripsy.

Extra corporeal shockwave lithotripsy (ESWL) is the treatment of choice for the majority of renal stones, however, it has the lowest success rate in complete clearance of stones located in the lower pole. We assess whether pelvi-calyceal height is a useful measurement in predicting successful stone clearance from the lower pole. A total of 105 patients with a solitary lower pole calculus of less than 20 mm treated with ESWL were reviewed. Stone size, location and pelvi-calyceal height were measured by intravenous urogram. Success was defined as complete stone clearance. Fifty-four patients (51.4%) had successful treatments, with the remaining 51 (48.6%) having incomplete stone clearance (including two patients in whom treatment had no effect). There was a statistically significant difference (P<0.0001) in pelvi-calyceal height between the two groups. Mean pelvi-calyceal height in patients with complete stone clearance was 15.1 mm (SD=3.9) compared with 22.9 mm (SD=5.2) for those with incomplete clearance. Pelvi-calyceal height is a useful predictor of success when treating lower pole renal stones with ESWL.

Adult↗
PubMed2001

Composition of the spindle pole body of Saccharomyces cerevisiae and the proteins involved in its duplication.

The microtubule-organizing center (MTOC) is the organelle that manages the distribution of microtubule filaments in the cell. It includes such centers of microtubule organization as basal bodies, nucleus-associated bodies, spindle pole bodies and centrosomes. The centrosome is the MTOC in most animal cells. Despite the numerous studies that have been published on this organelle over the past 100 years, the protein composition of the animal centrosome remains poorly defined. In order to study the MTOC, many researchers have chosen the budding yeast Saccharomyces cerevisiae as a model organism. This review summarizes the budding yeast MTOC, referred to as the spindle pole body (SPB), including its structure and function, its components and the factors involved in its duplication. Electron microscopy and high-voltage electron tomographic analysis of this organelle have contributed to the understanding of its morphology, whereas analysis by matrix-assisted laser desorption/ionization has played a major role in identifying many of the spindle pole components. In addition, genetic and biochemical studies have revealed the functional and physical relationships of certain spindle pole components and proteins important for SPB duplication.

Adenosine Triphosphatases↗
PubMed2006

Laparoscopic subtotal splenectomy in hereditary spherocytosis : to preserve the upper or the lower pole of the spleen?

BACKGROUND: Clinical manifestations of hereditary spherocytosis can be controlled by splenectomy. The use of this procedure has been restricted due to concerns regarding exposure of patients to a lifelong risk of overwhelming infections. Subtotal splenectomy, which removes 85-90% of the enlarged spleen, is a logical alternative. In the first cases performed by laparoscopy we have chosen to preserve the upper pole. However, this technique showed some disadvantages, especially concerning the correct intraoperative evaluation of the splenic remnant volume. Therefore, we developed a new variant of the procedure by preserving the lower pole of the spleen. METHODS: Based on the authors' experience in laparoscopy (176 laparoscopic splenectomies), 10 laparoscopic subtotal splenectomies were performed in patients with hereditary microspherocytosis, preserving either the upper or the lower splenic pole. RESULTS: Patient age ranged between 5 and 35 years. The mean volume of the remnant spleen was 41.4 cm3. There were no complications, and no transfusions were needed. Follow-up for 1-30 months was available. CONCLUSIONS: Subtotal splenectomy appears to control hemolysis while maintaining splenic function. The laparoscopic approach is safe and effective and should be considered the procedure of choice in hereditary microspherocytosis. Laparoscopic subtotal splenectomy presents an advantage over open subtotal splenectomy, resulting in decreased blood loss, shorter hospital stay, no conversions, fewer operative and postoperative complications, and excellent remission rates. On the basis of our experience, the preservation of the lower pole of the spleen seems to be a first-line option for the optimal evaluation of the residual splenic mass.

Adult↗
PubMed1986

Functions of maternal mRNA as a cytoplasmic factor responsible for pole cell formation in Drosophila embryos.

Injection of mRNA extracted from Drosophila cleavage embryos or mature oocytes restored pole cell-forming ability to embryos that had been deprived of this ability by uv irradiation. However, mRNA extracted from blastoderms did not show the restoration activity. Pole cells thus formed in uv-irradiated embryos bear similarities to normal pole cells both in their morphology and their ability to migrate to the gonadal rudiments. But this mRNA does not appear to be capable of rescuing uv-induced sterility, or inducing pole cells in the anterior polar region.

Animals↗
PubMed1991

Spindle pole centrosomes of sea urchin embryos are partially composed of material recruited from maternal stores.

The spindle poles of fertilized sea urchin eggs have commonly been modeled as being derived from the centrosomes of the fertilizing spermatozoon. Boveri's theory of fertilization, proposed at the turn of the century, states that the maternal centrosome is suppressed or inactivated during oogenesis and that the sperm centrosome is functionally dominant. In support of this proposal, more recent studies have shown that the sperm imports a determinant that is involved in centrosomal replication. Examination of sea urchin zygotes immunofluorescently labeled with a new anti-centrosomal antibody by quantitative confocal laser-scanning microscopy shows, however, that spindle pole centrosomes are not exclusively paternal structures, but additionally contain material derived from maternal pools. Furthermore, this maternal centrosomal material is divided among daughter blastomeres during cleavage. It therefore appears that although the sperm centrosome plays a dominant role in organizing the spindle poles, much of the centrosomal material within the spindle poles of the zygote is actually recruited from preexisting egg cytoplasmic stores. These data indicate that centrosomes of sea urchin embryos are biparentally derived, composite organelles.

Animals↗
PubMed1988

A 6-pole filter for improving the readability of muscle contaminated EEGs.

A multi-channel switched-capacitor 6-pole filter for significantly reducing the EMG artifact present during seizures recorded by long-term monitoring procedures has been implemented for routine use. This permits repeated replay of the seizures with different filter settings. All of the channels can be simultaneously dialed to any cut-off frequency (3 dB down) between 8 Hz and 70 Hz and the event replayed for filtering and write-out onto any standard EEG machine. The advantage of the 6-pole switched-capacitor filter is that it does not require a complex design with high precision RC components. The cut-off frequency is determined by the frequency of a simple clock that is used to select the same cut-off point for all 16 channels. By changing the clock frequency, the operator moves the cut-off point linearly. The dramatic improvement obtained by off-line digital filtering that was recently reported (Gotman et al. 1981) indicates that more efficient filtering of EMG contaminated seizures is diagnostically significant in selected cases. This approach is limited by the availability and expense of not only the computer's hardware but also the dedicated software. Specially designed 4-pole analog filters (Barlow 1984) are less expensive than digital filtering, but are difficult to design even at specific frequencies and do not allow for a range of frequencies. The switched-capacitor 6-pole filters have all the advantages of the above but are even more efficient in reducing EMG artifact. They also do not have any of the above disadvantages and cost only a few dollars per channel.

Adult↗
PubMed1992

Overexpression of oskar directs ectopic activation of nanos and presumptive pole cell formation in Drosophila embryos.

In Drosophila, a small group of maternal effect genes, including oskar, defines a shared pathway leading to the provision of two determinants at the posterior pole of the embryo. One determinant is the posterior body patterning morphogen nanos, and the other directs germ cell formation. Overexpression of oskar causes the shared pathway to be hyperactivated, with excess nanos activity present throughout the embryo and a superabundance of posterior pole cells. In addition, presumptive pole cells appear at a novel anterior position. Strikingly, formation of these ectopic pole cells is enhanced in nanos mutants. This observation may reflect competition between nanos and the germ cell determinant for a shared and limiting precursor.

Animals↗
PubMed1991

Simulated scaphoid proximal pole fracture.

Five fresh cadaver upper extremities were studied with use of a static positioning frame, pressure-sensitive film, a microcomputer-based videodigitizing system, and a Sun station image analysis system to assess the load bearing characteristics of the scaphoid in the proximal carpal joint. Specimens were studied in their normal condition, after a proximal pole osteotomy of the scaphoid, and after resection of the proximal pole of the scaphoid. The amount of contact area born through the scaphoid fossa was essentially the same whether the scaphoid was intact, or after a simulated scaphoid fracture of its proximal pole, or after resection of the proximal pole. The scaphoid contact area and pressure, although overall relatively constant, was redistributed after osteotomy, resulting in increased contact area under the distal fragment and no change or a slight decrease in the contact area under the proximal fragment of the scaphoid. After resection of the proximal fragment, all scaphoid contact area and pressure was born by the distal scaphoid fragment. The contact area and pressure characteristics of the lunate remained unchanged in all conditions compared with the normal condition. There were no significant changes in the locations of the centroids of the scaphoid segments and the lunate in any of the conditions tested.

Adult↗
PubMed1989

Cellular polarity in cultured animal pole cells of Xenopus embryos.

The expression of intracellular and surface polarity in cultured animal pole cells of Xenopus embryos (stages 6, 8, and 10) was examined morphologically and immunocytochemically. When control embryos reached stage 23, daughter cells derived from a single or a few animal pole cells formed aggregates. Outer cells of the aggregates displayed intracellular and surface polarity and expressed an epidermis-specific antigen (XEP-1) on the apical surface circumference, while these characteristics had not yet been established in the animal pole cells at the time of isolation. However, inner cells of the aggregates did not display the cellular polarity along an outer-inner axis of the aggregates and displayed the antigen randomly within the aggregates. These results indicate that the expression of cellular polarity in epidermal differentiation of Xenopus embryos in vitro depends on the position within the aggregates formed by daughter cells derived from isolated animal pole cells.

Animals↗
PubMed1988

Molecular analysis of a cytoplasmic factor essential for pole cell formation in Drosophila embryos.

This article reviews recent analytical studies of cytoplasmic factors involved in a mechanism underlying pole cell formation in Drosophila embryogenesis. Polar plasm, or germ plasm, includes sources of two independent functions in the germ-line segregation from the somatic line: pole cell formation and commitment of pole cells to germ cells. The UV-caused inability of pole cell formation in embryos was restored by poly(A)+ RNA, of which cDNA was cloned. The nucleotide sequence of the cDNA was highly homologous with mitochondrial large rRNA.

Animals↗
PubMed2005

Transformation proteins and DNA uptake localize to the cell poles in Bacillus subtilis.

The Gram-positive, rod-forming bacterium Bacillus subtilis efficiently binds and internalizes transforming DNA. The localization of several competence proteins, required for DNA uptake, has been studied using fluorescence microscopy. At least three proteins (ComGA, ComFA, and YwpH) are preferentially associated with the cell poles and appear to colocalize. This association is dynamic; the proteins accumulate at the poles as transformability develops and then delocalize as transformability wanes. DNA binding and uptake also occur preferentially at the cell poles, as shown using fluorescent DNA and in single-molecule experiments with laser tweezers. In addition to the prominent polar sites, the competence proteins also localize as foci in association with the lateral cell membrane, but this distribution does not exhibit the same temporal changes as the polar accumulation. The results suggest the regulated assembly and disassembly of a DNA-uptake machine at the cell poles.

Bacillus subtilis↗
PubMed2004

Microtubule nucleation at non-spindle pole body microtubule-organizing centers requires fission yeast centrosomin-related protein mod20p.

BACKGROUND: Many types of differentiated eukaryotic cells display microtubule distributions consistent with nucleation from noncentrosomal intracellular microtubule organizing centers (MTOCs), although such structures remain poorly characterized. In fission yeast, two types of MTOCs exist in addition to the spindle pole body, the yeast centrosome equivalent. These are the equatorial MTOC, which nucleates microtubules from the cell division site at the end of mitosis, and interphase MTOCs, which nucleate microtubules from multiple sites near the cell nucleus during interphase. RESULTS: From an insertional mutagenesis screen we identified a novel gene, mod20+, which is required for microtubule nucleation from non-spindle pole body MTOCs in fission yeast. Mod20p is not required for intranuclear mitotic spindle assembly, although it is required for cytoplasmic astral microtubule growth during mitosis. Mod20p localizes to MTOCs throughout the cell cycle and is also dynamically distributed along microtubules themselves. We find that mod20p is required for the localization of components of the gamma-tubulin complex to non-spindle pole body MTOCs and physically interacts with the gamma-tubulin complex in vivo. Database searches reveal a family of eukaryotic proteins distantly related to mod20p; these are found in organisms ranging from fungi to mammals and include Drosophila centrosomin. CONCLUSIONS: Mod20p appears to act by recruiting components of the gamma-tubulin complex to non-spindle pole body MTOCs. The identification of mod20p-related proteins in higher eukaryotes suggests that this may represent a general mechanism for the organization of noncentrosomal MTOCs in eukaryotic cells.

Amino Acid Sequence↗
PubMed2005

The WHO dose pole for the administration of praziquantel is also accurate in non-African populations.

In 2001, WHO developed a pole for the administration of praziquantel without the use of weighing scales, with encouraging results in African populations. In the present study, the pole was tested on height/weight data from 9354 individuals from 11 non-African countries. In more than 98% of the individuals (95% CI 97.8-98.4) the pole estimated an acceptable dosage (30-60 mg/kg), a performance statistically similar to that observed in African populations. Reproducing the present pole in the form of a strip of paper and including it in each container of praziquantel would greatly facilitate the administration of the drug in large-scale interventions.

Adolescent↗
PubMed2005

Randomized controlled study of mechanical percussion, diuresis, and inversion therapy to assist passage of lower pole renal calculi after shock wave lithotripsy.

OBJECTIVES: To determine whether mechanical percussion, diuresis, and inversion (PDI) therapy after shock wave lithotripsy (SWL) improves the clearance rates of lower pole renal stones. METHODS: In this single-blind study, 108 patients who underwent SWL treatment for lower pole renal stones with a total diameter of 2 cm or less were prospectively randomized into two groups. One group (n = 49) received SWL only and the other group (n = 59) received a median of four sessions of PDI therapy (range 1 to 12), 1 to 2 weeks after each SWL session. PDI therapy was performed as follows. Patients drank 500 mL of water 30 minutes before therapy; they then lay in a prone Trendelenburg position on a 45 degrees -angle couch, and received continuous 10-minute manual mechanical percussion applied over the flank. Stone clearance was documented with plain abdominal radiography, with additional imaging, if indicated, 1 and 3 months after initial SWL therapy. RESULTS: The patients from both groups were comparable in terms of total stone diameter, infundibular neck diameter, infundibular length, caliceal height, infundibular-pelvic angles, infundibular-ureteral angles, infundibular-vertebral angles, lower pole cortical thickness, and caliceal number. All patients underwent a maximum of four SWL treatments. For all assessable patients, the radiologically documented complete stone clearance rate at 3 months for the SWL-alone group was 35.4% and for the SWL plus PDI group was 62.5% (chi-square test, P = 0.006). CONCLUSIONS: PDI therapy is a valuable adjunct in assisting passage of lower pole renal stone fragments after SWL therapy.

Adolescent↗
PubMed2006

Integration of one- and two-dimensional motion signals in infants: evidence from the barber-pole illusion.

Several previous studies in adults have investigated how one- and two-dimensional moving features are integrated into a coherent global motion percept by studying the "barber-pole illusion"; when a one-dimensional moving grating is presented within a rectangular aperture, the two-dimensional line terminators at the edges of the aperture bias the perceived direction of motion toward the longer axis of the aperture. In the current study, we used barber-pole stimuli to investigate the development of motion mechanisms that integrate one- and two-dimensional motion signals. Using a directional eye movement technique, we measured responses to obliquely moving gratings presented within horizontally vs. vertically oriented apertures, in infants (ages 2-5 months) and adults. For all ages, we found that horizontal eye movements were significantly stronger when gratings were presented within horizontal than within vertical apertures, as predicted by the barber-pole illusion. Additionally, we devised a way to infer the "effective shift" in eye movement direction produced by the barber-pole illusion. Using a simple motion integration model, effective shift values were then used to calculate the relative weightings of one- and two-dimensional motion signals to direction coding. The results show that by 2 months of age, infants integrate one- and two-dimensional motion signals, and that the relative weighting of one- and two-dimensional signals remains roughly constant from 2 months of age into adulthood.

Adult↗
PubMed2005

Secondary heart field contributes myocardium and smooth muscle to the arterial pole of the developing heart.

The arterial pole of the heart is the region where the ventricular myocardium continues as the vascular smooth muscle tunics of the aorta and pulmonary trunk. It has been shown that the arterial pole myocardium derives from the secondary heart field and the smooth muscle tunic of the aorta and pulmonary trunk derives from neural crest. However, this neural crest-derived smooth muscle does not extend to the arterial pole myocardium leaving a region at the base of the aorta and pulmonary trunk that is invested by vascular smooth muscle of unknown origin. Using tissue marking and vascular smooth muscle markers, we show that the secondary heart field, in addition to providing myocardium to the cardiac outflow tract, also generates prospective smooth muscle that forms the proximal walls of the aorta and pulmonary trunk. As a result, there are two seams in the arterial pole: first, the myocardial junction with secondary heart field-derived smooth muscle; second, the secondary heart field-derived smooth muscle with the neural crest-derived smooth muscle. Both of these seams are points where aortic dissection frequently occurs in Marfan's and other syndromes.

Animals↗
PubMed1998

Efficacy and cost-effectiveness of extracorporeal shock wave lithotripsy for solitary lower pole renal calculi.

PURPOSE: We determined the efficacy of extracorporeal shock wave lithotripsy monotherapy and compared its cost-effectiveness with percutaneous nephrolithotomy for the management of lower pole renal calculi. MATERIALS AND METHODS: The efficacy (stone-free rates at 3-months posttreatment) of shock wave lithotripsy with the modified Dornier HM3* machine was determined retrospectively in 114 patients with solitary lower pole renal calculi. Using cost data available from patient billing charges and efficacy data from the literature, the cost-effectiveness for percutaneous nephrolithotomy and shock wave lithotripsy as primary therapy was evaluated. To make this cost-effectiveness comparison, we developed a decision analysis model in which a patient in whom primary therapy failed was rendered stone-free with a secondary percutaneous nephrolithotomy procedure. RESULTS: The stone-free rates of solitary lower pole stones with a size range of less than 10, 11 to 20 and greater than 20 mm. were 76, 74 and 33%, respectively, with a single shock wave lithotripsy treatment. Based on average treatment costs for shock wave lithotripsy and percutaneous nephrolithotomy, the model results show that for stone sizes less than 2 cm. primary lithotripsy therapy followed by nephrolithotomy for failed cases is the least costly approach. For stone sizes greater than 2 cm. primary percutaneous nephrolithotomy may be more cost-effective. CONCLUSIONS: Whereas shock wave lithotripsy with the Dornier HM3 should be considered the initial treatment choice for most lower pole stones less than 2 cm., primary percutaneous nephrolithotomy should be considered for stones larger than 2 cm.

Cost-Benefit Analysis↗
PubMed2002

Histology of upper pole is unaffected by prenatal diagnosis in duplex system ureteroceles.

PURPOSE: We determined whether the histology of upper pole nephrectomy specimens vary with prenatal detection or ureterocele position. MATERIALS AND METHODS: Between 1992 and 2000, 95 patients with ureteroceles associated with a duplex system underwent surgical interventions, including upper pole nephrectomy in 60. A total of 55 specimens, of which 25 and 30 involved a prenatal and postnatal diagnosis, and 18 and 37 involved an intravesical and extravesical location, respectively, were available for independent review by a single pathologist. Histological lesions were classified into the 5 categories of chronic interstitial inflammation, fibrosis, tubular atrophy, glomerulosclerosis and dysplasia. Each category was divided into moderate/severe histological lesions (greater than 25% involvement) and minimal/mild lesions (25% or less involvement). RESULTS: A moderate/severe histological lesion was identified in 38 patients (69%) and a minimal/mild lesion was detected in 17 (31%), while dysplasia was present in 35 (64%). There was no significant difference in histological lesions and mode of presentation. In contrast to intravesical ureteroceles, extravesical ureteroceles were associated with severe fibrosis and tubular atrophy (p <0.05). Chronic interstitial inflammation, fibrosis, tubular atrophy and glomerulosclerosis in each specimen were graded moderate/severe (greater than 25% involved) in 55%, 67%, 66% and 53%, respectively. CONCLUSIONS: Prenatally diagnosed ureteroceles were not associated with less severe upper pole histological lesions. We noted pathological differences when comparing specimens according to ureterocele position, but chronic inflammation and dysplasia were similar in intravesical and extravesical ureterocele cases. It appears that the histological lesions observed are not progressive or reversible. Therefore, the goals of clinical management should focus on providing adequate drainage, antibiotic prophylaxis coverage and followup of reflux rather than the preservation or enhancement of upper pole function.

Child↗