bluuebunny/crossref_metadata_2025 huggingface dataset:
Light‐dependent and Biochemical Properties of Two Different Bands of Bacteriorhodopsin Isolated on Phenyl‐Sepharose CL‐4B
Authors: Lopez Francesco , Lobasso Simona , Colella Matilde , Agostiano Angela , Corcelli Angela
Published: January 2008

Abstract— We report a detailed description of the light‐dependent and biochemical properties of two different bands of isolated and nearly delipidated bacteriorhodopsin obtained from chromatography on phenyl‐Sepharose CL‐4B. The two bands (BR I and BR II) showed a number of markedly different spectroscopic and biochemical characteristics: different absorption maximums in the dark, different light/dark adaptations, different M decay kinetics, different stabilities, different responses to titration with alkali in the dark and different circular dichroism (CD) spectra. Organic phosphate contents of BR I and BR II were measured; we found that more than 90% of purple membrane organic phosphate was removed in the course of chromatography and that the phospholipid/protein molar ratio was always higher in BR I than in BR II. In many functional aspects (high stability, response to light adaptation, spectral changes in the dark by alkali addition and bilobate CD spectrum) the first band appeared to be similar to the purple membrane. We suggest that the functional differences between the two bands depend on the fact that the first band (BR I) contains mostly bacteriorhodopsin aggregates corresponding to purple membrane trimers, while the second band (BR II) contains only bacteriorhodopsin monomers.
Light Dose Fractionation to Enhance Photodynamic Therapy Using 5‐Aminolevulinic Acid in the Normal Rat Colon
Authors: Curnow Alison , Mcllroy Brian W. , Postle‐Hacon Matthew J. , MacRobert Alexander J. , Bown Stephen G.
Published: January 2008

Abstract— 5‐Aminolevulinic acid (ALA) is an attractive photosensitizing agent for photodynamic therapy (PDT) as its photoactive derivative, protoporphyrin IX, is metabolized within 1–2 days, eliminating prolonged skin photosensitivity. However, at the maximum dose patients can tolerate by mouth, 60 mg/kg, only superficial effects are seen. This paper extends earlier studies on enhancing the effect by light fractionation. Experiments in the normal rat colon looked at the area of necrosis around a single light delivery fiber 3 days after PDT with a range of light‐dose fractionation regimes. All animals were given 200 mg/kg ALA intravenously 2 h prior to light delivery (100 mW at 635 nm) and each interruption in illumination was for 150 s. The area of PDT necrosis (total dose 25 J) could be increased by a factor of 3 with a single interval after 5 J, compared with continuous illumination. Alternatively, with this single break, the total Light dose could be reduced by 60% to achieve the same area of necrosis as with continuous illumination. This simple modification to PDT with ALA could markedly reduce current treatment times as well as increasing clinical efficacy.
Lysosomes Are Sites of Fluoroquinolone Photosensitization in Human Skin Fibroblasts: A Microspectrofluorometric Approach*
Authors: Ouedraogo G. , Morliere P. , Bazin M. , Santus R. , Kratzer B. , Miranda M. A. , Castell J. V.
Published: January 2008

Abstract.The fluoroquinolone antibiotics are widely used despite their strong phototoxicity under solar UV irradiation. Although they are known as good photodynamic photosen‐sitizers, other factors than production of activated oxygen species may play a role in the effectiveness of the phototoxic effect. Subcellular localization is one of the important parameters that may determine this strength. Using microspectrofluorometry, it is shown that norfloxacin, ofloxacin, lomefloxacin, ciproflaxin and BAYy3118 are readily incorporated into lysosomes of HS68 human skin fibroblasts although weak staining of the whole cytoplasm also occurs especially with norfloxacin. Consistent with their photoinstability in solutions, the fluoroquinolones under study are readily photobleached by UVA in the HS68 fibroblasts. The BAYy3118 derivative that has the fastest bleaching rate also shows the strongest phototoxicity toward HS68 fibroblasts. Photosensitization with these fluoroquinolones induces lysosomal membrane damage as shown by the increased rate of leakage of the lysosomal probe lucifer yellow as compared to that observed with untreated cells.
Action Spectrum for the Photophobic Response of Ciona intestinalis (Ascidieacea, Urochordata) Larvae Implicates Retinal Protein
Authors: Nakagawa Masashi , Miyamoto Takayuki , Ohkuma Mahito , Tsuda Motoyuki
Published: January 2008

Abstract Ascidian tadpole larvae change swimming behavior during the course of development. The photic behavior of the larvae of Ciona intestinalis was monitored by a computerized cell‐tracking system with a time resolution of 0.1 s. Newly hatched larvae swim at an average speed of 1.4 mm/s but show no response to light stimuli. The swimming speed of the larvae became slower (0.4 mm/s) 3 h after hatching and they were induced to swim more rapidly by a sudden decrease in light intensity 4 h after hatching. During the course of development, the maximal speed of swimming behavior increased with time until 8 h after hatching and then plateaued. The action spectrum for the step‐down photophobic response of the larvae was determined at around 8 h after hatching and was fitted to Dartnall's nomogram with the absorbance maximum of the pigment located at 505 nm. These results suggest retinal proteins in the ocellus of the larvae are the photoreceptors for the photobehavior.
Reactivity of Singlet Oxygen with Tryptophan Residues and with Melittin in Liposome Systems
Authors: Vilensky Anna , Feitelson Jehuda
Published: January 2008

The reactivity of singlet oxygen, 1O2, with amino acids, polypeptides and proteins has been studied extensively in solution, in micelles and also in vesicles. Here we attempt to examine its reactivity with iV‐acetyltryptophan amide (NATA), with a tryptophan residue with a long aliphatic chain attached, Trp(CH2)16, and with melittin–a small membrane protein–in a solution containing liposomes. In such a heterogeneous system the sensitizer and/or the tryptophan residue can be located in the ambient DzO, in the liposome membrane or at the membrane‐solution interface. The sensitizer meso‐tetra(N‐methyl‐4 pyri‐dyDporphine tetratosylate (mTPTT) is located in the aqueous phase while hematoporphyrin (HP) is embedded in the membrane. The quenching of 1O2 by the tryptophan residues and by melittin in solution, when using either of the sensitizers, was compared with the data in the liposome‐containing system. It was found that the location of the sensitizer and of the quencher in the liposome membrane or in the surrounding solution greatly affects the quenching rate constants of 1O2.
Singlet Oxygen Toxicity Is Cell Line‐dependent: A Study of Lipid Peroxidation in Nine Leukemia Cell Lines
Authors: Schafer Freya Q. , Buettner Garry R.
Published: January 2008

Singlet oxygen (1O2) can be quenched by water, lipids, proteins, nucleic acids and other small molecules. Polyunsaturated fatty acids (PUFA) of cells principally quench 1O2 by chemical mechanisms, producing lipid hydroperoxides, while proteins physically and chemically quench 1O2. Because cell lines can have different PUFA and protein levels, we hypothesized that 1O2 toxicity will vary between cell lines. We used Photofrin® as a source of 1O2. Exposure of nine different leukemia cell lines (CEM, HEL, HL‐60, K‐562, KG‐1, L1210, Molt‐4, THP‐1 and U‐937) to Photofrin and light results in changes in membrane permeability (trypan blue) that vary with cell line. The greater the lipid content of the cell line, the less susceptible they are to membrane damage. When the cell media was supplemented with docosahexaenoic acid (DHA, 22:6), the overall unsaturation of cellular lipids increased. Photofrin and light resulted in increased radical formation in these supplemented cells compared to controls; however, there was no difference in membrane permeability between DHA‐supplemented and control cells. Lipid‐derived radical formation (electron paramagnetic resonance spin trapping) was cell line dependent; but no correlation between lipid content of cells and radical formation was found. However, we found that the greater the protein content of cells the more they were protected against membrane damage induced by Photofrin photosensitization. This suggests that cellular proteins are a key target for 1O2‐mediated toxicity. A remarkable observation is that cell size correlates inversely with ability of cells to cope with a given flux of 1O2.
Laser Fluence for Permanent Damage of Cutaneous Blood Vessels
Authors: Barton Jennifer Kehlet , Vargas Gracie , Pfefer T. Joshua , Welch Ashley J.
Published: January 2008

Treatment of vascular disorders may be improved by a more thorough understanding of laser‐blood vessel interaction. In this study, the probability of permanent damage to a given type and size of blood vessel was determined as a function of fluence at the top (superficial edge) of the vessel lumen. A 532 nm wavelength, 10 ms pulse duration, 3 mm spot size laser was used to perform approximately 250 irradiations of subdermal blood vessels in the hamster dorsal skin flap preparation. The radiant exposure required for a 50% probability of permanent damage was calculated using a probit analysis of experimental results. Threshold radiant exposure increased with larger blood vessel diameters and was greater for arterioles than venules. Monte Carlo modeling of a typical blood vessel geometry revealed that fluence at the top of the blood vessel lumen was amplified by a factor of approximately 2.4 over tissue surface radiant exposure, due to light scattering in the tissue and internal reflection at the skin‐air interfaces.
Cell Density–Dependent Increase of Constitutive Signal Transducers and Activators of Transcription 3 Activity in Melanoma Cells Is Mediated by Janus Kinases
Authors: Kreis Stephanie , Munz Georg A. , Haan Serge , Heinrich Peter C. , Behrmann Iris
Published: January 2008

Signal transducers and activators of transcriptions (STAT) are key mediators of cytokine signaling. Moreover, these transcription factors play a crucial role in oncogenic signaling where inappropriate and sustained activation of STATs, especially STAT3, is a trait of many different cancers and their derived cell lines. Constitutively active STAT3 has been reported to prevent programmed cell death and enhance cell proliferation, whereas the disruption of STAT3 signaling can inhibit tumor growth. The physiologic activation of STAT3 by cytokines has been well established; however, little is known about altered, stimulation-independent STAT3 activation. Here, we show that, in most but not all melanoma cell lines, STAT3 phosphorylation increased substantially with cell density and that this STAT3 was able to bind to DNA and to activate transcription. Inhibitor studies showed that the cell density–dependent STAT3 activation relies on Janus kinases (JAK) rather than Src kinases. Using a specific JAK inhibitor, sustained STAT3 activation was completely abrogated in all tested melanoma lines, whereas inhibition of Src or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 had no effect on constitutively tyrosine-phosphorylated STAT3 levels. Although STAT3 activation was completely blocked with JAK inhibitor I and to a lesser extent with the common JAK inhibitor AG490, only the latter compound markedly decreased proliferation and induced apoptosis. Taken together, variations in cell density can profoundly modify the extent of JAK-mediated persistent STAT3 phosphorylation; however, STAT3 activation was not sufficient to provide critical growth and survival signals in melanoma cell lines. (Mol Cancer Res 2007;5(12):1331–41)
Construction of a Biological Tissue Model Based on a Single-Cell Model: A Computer Simulation of Metabolic Heterogeneity in the Liver Lobule
Authors: Ohno Hiroshi , Naito Yasuhiro , Nakajima Hiromu , Tomita Masaru
Published: January 2008

An enormous body of information has been obtained by molecular and cellular biology in the last half century. However, even these powerful approaches are not adequate when it comes to higher-level biological structures, such as tissues, organs, and individual organisms, because of the complexities involved. Thus, accumulation of data at the higher levels supports and broadens the context for that obtained on the molecular and cellular levels. Under such auspices, an attempt to elucidate mesoscopic and macroscopic subjects based on plentiful nanoscopic and microscopic data is of great potential value. On the other hand, fully realistic simulation is impracticable because of the extensive cost entailed and enormous amount of data required. Abstraction and modeling that balance the dual requirements of prediction accuracy and manageable calculation cost are of great importance for systems biology. We have constructed an ammonia metabolism model of the hepatic lobule, a histological component of the liver, based on a single-hepatocyte model that consists of the biochemical kinetics of enzymes and transporters. To bring the calculation cost within reason, the porto-central axis, which is an elemental structure of the lobule, is defined as the systems biological unit of the liver, and is accordingly modeled. A model including both histological structure and position-specific gene expression of major enzymes largely represents the physiological dynamics of the hepatic lobule in nature. In addition, heterogeneous gene expression is suggested to have evolved to optimize the energy efficiency of ammonia detoxification at the macroscopic level, implying that approaches like this may elucidate how properties at the molecular and cellular levels, such as regulated gene expression, modify higher-level phenomena of multicellular tissue, organs, and organisms.
Fear and Trembling in the American High School
Authors: Brooks Jeffrey S. , Hughes Roxanne M. , Brooks Melanie C.
Published: January 2008

This article reports findings from a two-year case study of teachers in a single public high school. Data were gathered and analyzed using a conceptual framework that conceived of alienation as a set of five sub-constructs: powerlessness, meaninglessness, normlessness, isolation, and estrangement. Findings suggested that teachers experienced each of these forms of alienation, but that each individual teacher interpreted them in a unique manner. Moreover, data suggested that for individual teachers, experiences of alienation varied from situation to situation and evolved over time. The authors concluded that teacher alienation was a fluid phenomenon, a seemingly basic assertion that has profound implications for teachers, administrators, and policymakers as they consider adopting or implementing reform initiatives.
A simple principle concerning the robustness of protein complex activity to changes in gene expression
Authors: Semple Jennifer I , Vavouri Tanya , Lehner Ben
Published: January 2008

Background

The functions of a eukaryotic cell are largely performed by multi-subunit protein complexes that act as molecular machines or information processing modules in cellular networks. An important problem in systems biology is to understand how, in general, these molecular machines respond to perturbations.

Results

In yeast, genes that inhibit growth when their expression is reduced are strongly enriched amongst the subunits of multi-subunit protein complexes. This applies to both the core and peripheral subunits of protein complexes, and the subunits of each complex normally have the same loss-of-function phenotypes. In contrast, genes that inhibit growth when their expression is increased are not enriched amongst the core or peripheral subunits of protein complexes, and the behaviour of one subunit of a complex is not predictive for the other subunits with respect to over-expression phenotypes.

Conclusion

We propose the principle that the overall activity of a protein complex is in general robust to an increase, but not to a decrease in the expression of its subunits. This means that whereas phenotypes resulting from a decrease in gene expression can be predicted because they cluster on networks of protein complexes, over-expression phenotypes cannot be predicted in this way. We discuss the implications of these findings for understanding how cells are regulated, how they evolve, and how genetic perturbations connect to disease in humans.
MetaReg: a platform for modeling, analysis and visualization of biological systems using large-scale experimental data
Authors: Ulitsky Igor , Gat-Viks Irit , Shamir Ron
Published: January 2008

MetaReg http://acgt.cs.tau.ac.il/metareg/application.html is a computational tool that models cellular networks and integrates experimental results with such models. MetaReg represents established knowledge about a biological system, available today mostly in informal form in the literature, as probabilistic network models with underlying combinatorial regulatory logic. MetaReg enables contrasting predictions with measurements, model improvements and studying what-if scenarios. By summarizing prior knowledge and providing visual and computational aids, it helps the expert explore and understand her system better.
Speed, Spatial, and Temporal Tuning of Rod and Cone Vision in Mouse
Authors: Umino Yumiko , Solessio Eduardo , Barlow Robert B.
Published: January 2008

Rods and cones subserve mouse vision over a 100 million-fold range of light intensity (−6 to 2 log cd m−2). Rod pathways tune vision to the temporal frequency of stimuli (peak, 0.75 Hz) and cone pathways to their speed (peak, ∼12°/s). Both pathways tune vision to the spatial components of stimuli (0.064–0.128 cycles/°). The specific photoreceptor contributions were determined by two-alternative, forced-choice measures of contrast thresholds for optomotor responses of C57BL/6J mice with normal vision,Gnat2cpfl3mice without functional cones, andGnat1−/−mice without functional rods.Gnat2cpfl3mice (threshold, −6.0 log cd m−2) cannot see rotating gratings above −2.0 log cd m−2(photopic vision), andGnat1−/−mice (threshold, −4.0 log cd m−2) are blind below −4.0 log cd m−2(scotopic vision). Both genotypes can see in the transitional mesopic range (−4.0 to −2.0 log cd m−2). Mouse rod and cone sensitivities are similar to those of human. This parametric study characterizes the functional properties of the mouse visual system, revealing the rod and cone contributions to contrast sensitivity and to the temporal processing of visual stimuli.
Taurine Is a Potent Activator of Extrasynaptic GABAAReceptors in the Thalamus
Authors: Jia Fan , Yue Minerva , Chandra Dev , Keramidas Angelo , Goldstein Peter A. , Homanics Gregg E. , Harrison Neil L.
Published: January 2008

Taurine is one of the most abundant free amino acids in the brain. In a number of studies, taurine has been reported to activate glycine receptors (Gly-Rs) at moderate concentrations (≥100 μm), and to be a weak agonist at GABAAreceptors (GABAA-Rs), which are usually activated at high concentrations (≥1 mm). In this study, we show that taurine reduced the excitability of thalamocortical relay neurons and activated both extrasynaptic GABAA-Rs and Gly-Rs in neurons in the mouse ventrobasal (VB) thalamus. Low concentrations of taurine (10–100 μm) decreased neuronal input resistance and firing frequency, and elicited a steady outward current under voltage clamp, but had no effects on fast inhibitory synaptic currents. Currents elicited by 50 μmtaurine were abolished by gabazine, insensitive to midazolam, and partially blocked by 20 μmZn2+, consistent with the pharmacological properties of extrasynaptic GABAA-Rs (α4β2δ subtype) involved in tonic inhibition in the thalamus. Tonic inhibition was enhanced by an inhibitor of taurine transport, suggesting that taurine can act as an endogenous activator of these receptors. Taurine-evoked currents were absent in relay neurons from GABAA-R α4 subunit knock-out mice. The amplitude of the taurine current was larger in neurons from adult mice than juvenile mice. Taurine was a more potent agonist at recombinant α4β2δ GABAA-Rs than at α1β2γ2 GABAA-Rs. We conclude that physiological concentrations of taurine can inhibit VB neurons via activation of extrasynaptic GABAA-Rs and that taurine may function as an endogenous regulator of excitability and network activity in the thalamus.
Differential Outgrowth of Axons and their Branches Is Regulated by Localized Calcium Transients
Authors: Hutchins B. Ian , Kalil Katherine
Published: January 2008

During development axon outgrowth and branching are independently regulated such that axons can stall or retract while their interstitial branches extend toward targets. Previous studies have shown that guidance cues and intracellular signaling components can promote branching of cortical axons without affecting axon outgrowth. However, the mechanisms that regulate differential outgrowth of axons and their branches are not well understood. Based on our previous work showing the importance of localized repetitive calcium transients in netrin-1-induced cortical axon branching, we sought to investigate the role of calcium signaling in regulating differential outgrowth of axons and their branches. Using fluorescence calcium imaging of dissociated developing cortical neurons, we show that localized spontaneous calcium transients of different frequencies occur in restricted regions of axons and their branches. Higher frequencies occur in more rapidly extending processes whereas lower frequencies occur in processes that stall or retract. Direct induction of localized calcium transients with photolysis of caged calcium induced rapid outgrowth of axonal processes. Surprisingly outgrowth of one axonal process was almost invariably accompanied by simultaneous retraction of another process belonging to the same axon, suggesting a competitive mechanism for differential process outgrowth. Conversely, reducing frequencies of calcium transients with nifedipine and TTX reduced the incidence of differential process outgrowth. Together these results suggest a novel activity-dependent mechanism whereby intrinsic localized calcium transients regulate the competitive growth of axons and their branches. These mechanisms may also be important for the development of cortical connectivityin vivo.
Universal Memory Mechanism for Familiarity Recognition and Identification
Authors: Yakovlev Volodya , Amit Daniel J. , Romani Sandro , Hochstein Shaul
Published: January 2008

Macaque monkeys were tested on a delayed-match-to-multiple-sample task, with either a limited set of well trained images (in randomized sequence) or with never-before-seen images. They performed much better with novel images. False positives were mostly limited to catch-trial image repetitions from the preceding trial. This result implies extremely effective one-shot learning, resembling Standing's finding that people detect familiarity for 10,000 once-seen pictures (with 80% accuracy) (Standing, 1973). Familiarity memory may differ essentially from identification, which embeds and generates contextual information. When encountering another person, we can say immediately whether his or her face is familiar. However, it may be difficult for us to identify the same person. To accompany the psychophysical findings, we present a generic neural network model reproducing these behaviors, based on the same conservative Hebbian synaptic plasticity that generates delay activity identification memory. Familiarity becomes the first step toward establishing identification. Adding an inter-trial reset mechanism limits false positives for previous-trial images. The model, unlike previous proposals, relates repetition–recognition with enhanced neural activity, as recently observed experimentally in 92% of differential cells in prefrontal cortex, an area directly involved in familiarity recognition. There may be an essential functional difference between enhanced responses to novel versus to familiar images: The maximal signal from temporal cortex is for novel stimuli, facilitating additional sensory processing of newly acquired stimuli. The maximal signal for familiar stimuli arising in prefrontal cortex facilitates the formation of selective delay activity, as well as additional consolidation of the memory of the image in an upstream cortical module.
LAPAROSCOPIC CHOLECYSTECTOMY IN CHILDREN: A 5-YEAR EXPERIENCE
Authors: Papandreou Evangelos , Gentimi Fotini , Baltogiannis Nikolaos , Livaditi Evangelia , Loukas Ierotheos , Christopoulos-Geroulanos Georgios
Published: January 2008

INTRODUCTION: Cholecystectomy in children is not a common surgical procedure. In the past 5 years, we have performed it laparoscopically. There was no difference in insufflated pressure between 2 groups while no drainage catheter was placed.

OBJECTIVE: We present a modified laparoscopic technique in children.

METHODS: In a 5-year period, 54 children underwent laparoscopic cholecystectomy. Their ages ranged from 14 months to 15 years (mean: 7.6 years). Depending on the applied technique, the patients were separated into 2 groups. The first group comprised 17 patients on whom we performed the conventional 4-port technique. The second group comprised 37 patients on whom a modified technique was performed. We used 3 ports: an umbilical port for the camera, another in the subxifoid region for the dissector, and a third in the right lower quadrant for the grasping clamp and the extraction of the gallbladder. Vessel sealing electrocautery was used for ligation of the cystic artery and detachment of the gallbladder.

RESULTS: Reduction of the number of ports had no effect on accessibility and duration of the procedure; however, it simplified access and handling, particularly in the smaller patients. Conversion to open cholecystectomy was performed in 1 case with major deformities of the vertebral column. The duration of hospitalization varied from 1 to 4 days (mean: 2.7 days).

CONCLUSIONS: The decreased number of ports and the use of vessel sealing electrocautery make laparoscopic cholecystectomy in children easier and safe, without affecting the perioperative time.
Hemorrhagic and nonhemorrhagic Rathke cleft cysts mimicking pituitary apoplexy
Authors: Binning Mandy J. , Liu James K. , Gannon John , Osborn Anne G. , Couldwell William T.
Published: January 2008

Object

Rathke cleft cysts (RCCs) are infrequently symptomatic, and apoplexy is one of the most unusual presentations. Only a few cases of apoplexy associated with RCCs have been reported, and their clinical, imaging, surgical, and pathological features are poorly understood. In the cases that have been reported, intracystic hemorrhage has been a consistent finding. The authors report 6 cases of RCCs in which the presenting clinical and imaging features indicated pituitary apoplexy, both with and without intracystic hemorrhage.

Methods

The authors retrospectively reviewed charts and magnetic resonance (MR) imaging studies obtained in patients who underwent transsphenoidal surgery for RCC. Six patients were identified who presented with symptoms and MR imaging characteristics consistent with pituitary apoplexy but were found intraoperatively to have an RCC. All 6 patients presented with a sudden headache, 2 with visual loss, and 1 with diplopia. Review of the preoperative MR images demonstrated mixed signal intensities in the sellar masses suggestive of a hemorrhagic pituitary tumor. In all patients there was a presumed clinical diagnosis of pituitary tumor apoplexy and an imaging-documented diagnosis of hemorrhagic pituitary tumor.

Results

All 6 patients underwent transsphenoidal resection to treat the suspected pituitary apoplexy. Intraoperative and histopathological findings were consistent with the diagnosis of an RCC in all cases. Only 2 cases showed evidence of hemorrhage intraoperatively. In all cases, an intracystic nodule was found within the RCC at surgery, and this intracystic nodule was present on the initial MR imaging when retrospectively reviewed. The imaging characteristics of the intracystic nodules were similar to those of acute hemorrhage seen in cases of pituitary apoplexy.

Conclusions

The clinical and imaging features of RCCs appear similar to those of hemorrhagic pituitary tumors, making them often indistinguishable from pituitary apoplexy.
Preoperative depiction of cavernous sinus invasion by pituitary macroadenoma using three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction imaging on a 3-tesla system
Authors: Yoneoka Yuichiro , Watanabe Naoto , Matsuzawa Hitoshi , Tsumanuma Itaru , Ueki Satoshi , Nakada Tsutomu , Fujii Yukihiko
Published: January 2008

Object

Three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) imaging provides clear depiction of neuronal fibers. The aim of this study was to identify intracavernous cranial nerves in patients with pituitary macro-adenoma and in healthy volunteers by using 3DAC MR imaging on a 3-tesla system and to preoperatively predict cavernous sinus invasion by pituitary macroadenoma.

Methods

Thirty-three patients (cavernous sinuses in 66 sides) with pituitary macroadenomas and 25 healthy volunteers (50 sides) participated in this study. Coronal 3DAC MR images constructed from diffusion weighted images, acquired with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) sequences, and T2-weighted reverse images were obtained at the same anatomical locations using a 3-tesla MR imaging system. Attempts were made to identify the cranial nerves.

Results

The oculomotor and ophthalmic/maxillary nerves were preoperatively identified in all sides (66 sides in patients and 50 sides in healthy volunteers) on 3DAC MR images. In the 33 patients, cavernous sinus invasion was revealed in 10 (12 [18.2%] of 66 sides) by intraoperative endoscopic observation. Coronal 3DAC MR images revealed that the oculomotor nerves were half surrounded with adenoma in all 12 of these sides, and the ophthalmic/maxillary nerves were half encapsulated with tumor (sensitivity/specificity: 100%/100% and 83%/100%, respectively).

Conclusions

Preoperative evaluation of pituitary macroadenomas using 3DAC PROPELLER MR imaging on a 3-tesla system is likely to be a powerful noninvasive method of detecting cavernous sinus invasion, which can potentially dominate the therapeutic strategy for these lesions.
Accuracy of the freehand pass technique for ventriculostomy catheter placement: retrospective assessment using computed tomography scans
Authors: Huyette David R. , Turnbow Benjamin J. , Kaufman Christian , Vaslow Dale F. , Whiting Benjamin B. , Oh Michael Y.
Published: January 2008

Object

The standard method of ventriculostomy catheter placement is a freehand pass technique using surface anatomical landmarks. This study was undertaken to determine the accuracy of successful ventriculostomy procedures performed at a single institution's intensive care unit (ICU). The authors hypothesized that use of surface anatomical landmarks alone with successful results frequently do not correlate with desirable catheter tip placement.

Methods

Retrospective evaluation was performed on the head computed tomography (CT) scans of 97 patients who underwent 98 freehand pass ventriculostomy catheter placements in an ICU setting. Using the postprocedure CT scans of the patients, 3D measurements were made to calculate the accuracy of ventriculostomy catheter placement.

Results

The mean distance (± standard deviation [SD]) from the catheter tip to the Monro foramen was 16 ± 9.6 mm. The mean distance (± SD) from the catheter tip to the center of the bur hole was 87.4 ± 14.0 mm. Regarding accurate catheter tip placement, 56.1% of the catheter tips were in the ipsilateral lateral ventricle, 7.1% were in the contralateral lateral ventricle, 8.2% were in the third ventricle, 6.1% were within the interhemispheric fissure, and 22.4% were within extraventricular spaces.

Conclusions

The accuracy of freehand ventriculostomy catheterization at the authors' institution typically required 2 passes per successful placement, and, when successful, was 1.6 cm from the Monro foramen. More importantly, 22.4% of these catheter tips were in nonventricular spaces. Although many neurosurgeons believe that the current practice of ventriculostomy is good enough, the results of this study show that there is certainly much room for improvement.
What are the implications in individuals with unilateral vestibular schwannoma and other neurogenic tumors?
Authors: Evans D. Gareth R. , Ramsden Richard T. , Shenton Andrew , Gokhale Carolyn , Bowers Naomi , Huson Susan M. , Wallace Andrew J.
Published: January 2008

Object

Individuals who develop a unilateral vestibular schwannoma (VS) and other neurogenic tumors are at high risk of having the inherited condition neurofibromatosis Type 2 (NF2). The risk of bilateral disease and transmission risk to offspring are important in surgical planning and counseling. The authors have attempted to resolve these risks.

Methods

A large NF2 dataset was interrogated for individuals who had initially presented with a unilateral VS and other tumors before developing bilateral disease, to assess the contralateral and offspring risks.

Results

Ninety-six patients with a unilateral VS and additional neurogenic tumors had a bilaterality rate of 48% at 20 years in those initially diagnosed when > 18 years of age and 82% if presenting earlier. Constitutional NF2 mutations were found in blood in 25 (27%) of 92, but 13 (76%) of 17 patients presenting with unilateral VS at ≤ 18 years of age. Tumor analysis suggests that the vast majority of the remainder are mosaic for an NF2 mutation.

Conclusions

Patients with unilateral VS and other NF2-related tumors who fulfill Manchester criteria have a high risk of developing a contralateral tumor, especially if presenting in childhood. Transmission risks are reduced for offspring, particularly in the older patients who are likely to be mosaic.
Cerebellar abscesses in children: excision or aspiration?
Authors: Pandey Paritosh , Umesh Srikantha , Bhat Dhananjaya , Srinivas Dwarakanath , Abraham Rojin , Pillai Shibu , Balasubramaniam Anandh , Devi Indira , Sampath Sommanna , Chandramouli Bengaluru A.
Published: January 2008

Object

Cerebellar abscesses are common neurosurgical emergencies in developing countries, and have a distressingly high mortality rate of 10 to 15% even today. There is still no consensus on the standard approach to these lesions, and controversy persists over whether these lesions should be treated with primary excision or aspiration.

Methods

The authors retrospectively analyzed 82 cases of cerebellar pyogenic abscesses in children treated at their institution over a period of 10 years. This represents the largest such series being described in literature. All lesions except 1 were otogenic in origin. The clinical and radiological features are discussed.

Results

Primary excision was undertaken in 66 patients (80%) and aspiration in 16 patients (20%). Five patients in whom the abscesses were initially treated with aspiration subsequently underwent elective excision. Nine (12.6%) of 71 patients in whom the abscesses were excised had residual abscesses on postoperative imaging; in those who had undergone aspiration as the primary treatment, 6 (54.5%) of 11 patients had recurrent abscesses. There were no deaths among the patients who underwent excision of the abscess. Also, excision of posterior fossa abscesses required fewer repeated procedures with lower recurrence rates, and statistically lower rate of complications.

Conclusions

Compared to primary aspiration, the authors found that primary excision is the preferred method for treating cerebellar abscesses.
Resection of intramedullary spinal cord tumors in children: assessment of long-term motor and sensory deficits
Authors: McGirt Matthew J. , Chaichana Kaisorn L. , Atiba April , Attenello Frank , Yao Kevin C. , Jallo George I.
Published: January 2008

Object

With modern surgical advances, radical resection of pediatric intramedullary spinal cord tumors (IMSCTs) can be expected to preserve long-term neurological function. Nevertheless, postoperative neurological decline is not uncommon after surgery, and many patients continue to experience long-term dysesthetic symptoms. Preoperative predictors of postoperative neurological decline and sensory syndromes have not been investigated and may serve as a guide for surgical risk stratification.

Methods

Neurological function (as determined using the modified McCormick Scale [mMS]) preoperatively, postoperatively, and 3 months after surgery was retrospectively recorded from patient charts in 164 consecutive patients undergoing resection of IMSCTs. A median 4 years (interquartile range [IQR] 1–8 years) after surgery, long-term motor and sensory symptoms were assessed by telephone interviews and corroborated by subsequent medical visits in 120 available patients. This long-term assessment was retrospectively reviewed for the purposes of this study. The authors reviewed this series to assess long-term motor, sensory, and urinary outcomes and to determine independent risk factors of postoperative neurological decline and long-term sensory dysfunction.

Results

Patients were 8.6 ± 5.7 years old and presented with a median mMS of 2 (IQR 2–4). Three months after surgery, 38 patients (23%) continued to experience decreased neurological function (1 mMS point) incurred perioperatively. Increasing age (p = 0.028), unilateral symptoms (p = 0.046), and urinary dysfunction at presentation (p = 0.004) independently predicted persistent 3-month perioperative decline. At long-term follow-up (median 4 years), 39 (33%) exhibited improvements in their mMS scores, 13 (30%) had improvement in their urinary dysfunction, and 27 (30%) had resolution of their dysesthesias. Seventy-eight patients (65%) experienced long-term dysesthetic symptoms. Increasing age (p = 0.024), preoperative symptom duration > 12 months (p = 0.027), and worsened postoperative mMS score at hospital discharge (p = 0.013) independently increased the risk of long-term dysesthesias.

Conclusions

In the authors' experience, nearly one third of patients may experience improvement in motor, sensory, and urinary dysfunction years after IMSCT resection, whereas the majority will continue to experience long-term dysesthetic symptoms. Improvement in motor deficits preceded improvement in sensory syndromes, and urinary dysfunction typically resolved much longer after surgery. The risk of persistent perioperative motor decline was increased with older age, unilateral symptoms, preoperative urinary symptoms, and less severe preoperative neurological deficit. The risk of long-term dysesthesias was increased with older age, increased duration of symptoms prior to resection, and greater postoperative neurological deficit.
Distribution of in vivo and in vitro range of motion following 1-level arthroplasty with the CHARITÉ artificial disc compared with fusion
Authors: Cunningham Bryan W. , McAfee Paul C. , Geisler Fred H. , Holsapple Gwen , Adams Karen , Blumenthal Scott L. , Guyer Richard D. , Cappuccino Andrew , Regan John J. , Fedder Ira L. , Tortolani P. Justin
Published: January 2008

Object

One of the goals of lumbar arthroplasty is to restore and maintain range of motion (ROM) and to protect adjacent levels from abnormal motion, which may be a factor in transition syndrome following arthrodesis. In this study, in vitro ROM results were compared with in vivo, 2-year postoperative radiographic ROM evaluations.

Methods

Radiographs of patients enrolled in the CHARITÉ investigational device exemption study were analyzed at baseline and at 2 years postoperatively. The ROM in flexion/extension at the implanted and adjacent levels was measured, normalized, and compared with ROM results obtained using cadaver (in vitro) evaluations.

Results

Preoperative ROM distributions in patients enrolled for arthroplasty or fusion at the L4–5 level was as follows: 28% motion was observed at L3–4, 35% at L4–5 and 37% at L5–S1. Following a one-level arthroplasty at L4–5, the in vivo ROM distribution from L-3 to S-1 at the 2-year time point was 36% at L3–4, 30% at L4–5 and 35% at L5–S1. Following a one-level fusion with BAK and pedicle screws at L4–5, the in vivo ROM distribution from L-3 to S-1 at the 2-year time point was 45% at L3–4, 9% at L4–5 and 46% at L5–S1.

Conclusions

The baseline as well as the 2-year in vivo data confirmed previously published in vitro data. One-level arthroplasty was shown herein to replicate the normal distribution of motion of the intact spine.
Calcium pyrophosphate dihydrate crystal deposition in the craniovertebral junction
Authors: Fenoy Albert J. , Menezes Arnold H. , Donovan Kathleen A. , Kralik Stephen F.
Published: January 2008

Object

Calcium pyrophosphate dihydrate (CPPD) deposition is a rare cause of retroodontoid mass lesions in elderly individuals. However, this condition may be severely underdiagnosed if sufficient attention is not paid to imaging characteristics and clinical presentation. The authors sought to evaluate the decision-making process in both the diagnosis and surgical treatment of CPPD.

Methods

A retrospective review of University of Iowa medical records and radiographs accumulated between 1977 and 2006 was performed. The inclusion criterion was histopathological findings consistent with pseudogout at the craniovertebral junction (CVJ). Twenty-one patients with a mean age of 70.3 years and a mean symptom duration prior to presentation of 17.5 months were identified and included in this study.

Results

The patients presented most frequently with occipital and neck pain (85%) and numbness or paresthesias (61%). Lower cranial nerve deficits were seen in 29%. Calcification of the mass or transverse ligament was seen on computed tomography in all included patients. Gross-total resection was achieved in all patients: 19 of 21 patients underwent transoral–transpalatopharyngeal resection, with only 16 requiring concomitant dorsal occipital–cervical fusion. The mean follow-up duration was 15 months. Eighteen patients (86%) had improvement or resolution of symptoms after treatment, and 3 were lost to follow-up.

Conclusions

Although rare, CPPD deposition at the CVJ should be suspected on finding calcification of and around the transverse ligament on neuroimaging. Transoral–transpalatopharyngeal resection is preferred to halt the progression of neurological deterioration; dorsal fusion is not always mandatory as concomitant ligamentous calcification and atlantoaxial joint ankylosis may provide added stability.
Cystic dilation of the ventriculus terminalis in adults
Authors: Ciappetta Pasqualino , D'urso Pietro Ivo , Luzzi Sabino , Ingravallo Giuseppe , Cimmino Antonia , Resta Leonardo
Published: January 2008

✓The ventriculus terminalis (VT) is a small ependyma-lined cavity within the conus medullaris that is in direct continuity with the central canal of the anterior portion of the spinal cord. Normally, such a cavity is identifiable only histologically in children and adults and can be visualized using common neuroradiological techniques only after dilation. Currently, the mechanisms of isolated dilation are not documented. The present work describes 2 cases of VT in elderly patients. Data from a histological and ultrastructural study of a case of VT dilation are reported, and the results are compared with those obtained from the VT of 5 fetuses to explain the nosological aspects of nontumoral VT lesions. Our data suggest that the site, age, and histological characteristics of the lesion allow us to define VT dilation as a nosological entity distinct from other cystic dilations of the conus medullaris.
Assessing Sensitivity to Antibacterial Topoisomerase II Inhibitors
Authors: Morgan‐Linnell Sonia K. , Hiasa Hiroshi , Zechiedrich Lynn , Nitiss John L.
Published: January 2008

Both prokaryotes and eukaryotes have two major classes of topoisomerases that make transient single‐ or double‐strand cuts in DNA. While these enzymes play critical roles in cellular processes, they are also important targets of therapeutic agents. This unit describes assays to use in characterizing topoisomerase II‐targeting agents in vitro and in bacterial cells. It provides protocols for characterizing the action of small molecules against bacterial type II topoisomerases in vitro and the in vivo effects of putative topoisomerase II‐targeting antibiotics, as well as for measuring trapped enzyme/DNA covalent complexes, the major cytotoxic lesion induced by fluoroquinolones. Curr. Protoc. Pharmacol. 39:3.13.1‐3.13.26. © 2007 by John Wiley & Sons, Inc.
Genetic variation of the FMR1 gene among four Mexican populations: Mestizo, Huichol, Purepecha, and Tarahumara
Authors: Barros‐Núñez Patricio , Rosales‐Reynoso Mónica Alejandra , Sandoval Lucila , Romero‐Espinoza Pavel , Troyo‐Sanromán Rogelio , Ibarra Bertha
Published: January 2008

Fragile X syndrome is the most common cause of inherited mental retardation; it is caused by expansion of CGG repeats in the first exon of the FMR1 gene. The number of CGG repeats varies between 6 and 50 triplets in normal individuals; the most common alleles have 29 or 30 repeats. Allelic patterns in the global populations are similar; however; some reports show statistical differences among several populations. In Mexico, except by a single report on a western Mestizo population, the allelic frequencies of the FMR1 gene are unknown. In this study, we analyze 207, 140, 138, and 40 chromosomes from Mestizos, Tarahumaras, Huichols, and Purepechas respectively. After PCR amplification on DNA modified by sodium bisulfite treatment, molecular analysis of the FMR1 gene showed 30 different alleles among the 525 chromosomes evaluated. Trinucleotide repeat number in the different Mexican populations varied from 15 to 87, with modal numbers of 32 and 30 in Mestizos and Tarahumaras, 29 and 32 in Purepechas and 30 among Huichols. Together, these allelic patterns differ significantly from those reported for Caucasian, Chinese, African, Indonesian, Brazilian, and Chilean populations. The increased number of the unusual allele of 32 repeats observed in the Mexican mestizo population can be explained from its frequency in at least two Mexican native populations. Am. J. Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.
Electrospinning of degradable elastomeric nanofibers with various morphology and their interaction with human fibroblasts
Authors: Borg Erik , Frenot Audrey , Walkenström Pernilla , Gisselfält Katrin , Gretzer Christina , Gatenholm Paul
Published: January 2008

Artelon® (degradable poly(urethane urea) elastomer) was electrospun into scaffolds for tissue engineering. The diameter of the electrospun fibers, studied by scanning electron microscopy, ranged from 100 nm to a few μm, with an average diameter of 750 nm. The molar mass of the polymer had a major influence on the morphology of the scaffold. Furthermore, aging of the polymer solution caused changes in viscosity, as measured by stress sweeps between 13.5–942 Pa that affected the morphology. The electrospun Artelon mats exhibited about the same elongations to break, both exceeding 200%, measured by tensile tests. The degradation study showed similar degradation behavior in electrospun mats and solids. In vitro study showed that human fibroblasts not only adhere to the surface but also migrate, proliferate, and produce components of an extracellular matrix. These results strongly support the use of electrospun Artelon as a scaffold in tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008