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1.
Pediatr Surg Int ; 36(5): 563-568, 2020 May.
Article in English | MEDLINE | ID: mdl-32232550

ABSTRACT

PURPOSE: This study evaluates the capacity of ultrasonography as a diagnostic method to confirm the proper positioning of central venous catheter (CVC) when compared to the current gold standard, chest radiography (CR). METHODS: A prospective study was performed including children from 0 to 14 incomplete years, who underwent CVC placement between March and May 2018 at a teaching hospital in Brazil. A four-chamber view of the heart was performed with ultrasound during a rapid injection of saline solution to identify hyperechoic images and confirm the central position of the catheter. After that, a CR was performed. The diagnostic quality of ultrasound was evaluated based on accuracy, sensitivity, specificity, positive and negative predictive values. RESULTS: A total of 21 patients were analyzed. The mean age was 3.95 ± 4.01 years. The preferred puncture site was the right internal jugular vein (71.4%). Ultrasound accuracy to detect CVC positioning was 81%. Sensitivity, specificity and positive and negative predictive values were 33%, 100%, 100% and 79%, respectively. CONCLUSION: Ultrasound is a reliable method for detection of CVC positioning. Even so, with the four-chamber cardiac view, this method is unable to identify catheters inside heart chambers, therefore, needing to confirm the positioning with CR.


Subject(s)
Catheterization, Central Venous/methods , Central Venous Catheters , Jugular Veins/diagnostic imaging , Radiography, Thoracic/methods , Ultrasonography/methods , Adolescent , Brachiocephalic Veins , Child , Child, Preschool , Equipment Design , Female , Humans , Infant , Infant, Newborn , Male , Prospective Studies , Punctures
2.
Mol Cell Biol ; 37(16)2017 Aug 15.
Article in English | MEDLINE | ID: mdl-28559431

ABSTRACT

We have detected DNA polymerase beta (Polß), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polß in the mitochondria. Using Polß fragments, mitochondrion-specific protein partners were identified, with the interactors functioning mainly in DNA maintenance and mitochondrial import. Of particular interest was the identification of the proteins TWINKLE, SSBP1, and TFAM, all of which are mitochondrion-specific DNA effectors and are known to function in the nucleoid. Polß directly interacted functionally with the mitochondrial helicase TWINKLE. Human kidney cells with Polß knockout (KO) had higher endogenous mitochondrial DNA (mtDNA) damage. Mitochondrial extracts derived from heterozygous Polß mouse tissue and KO cells had lower nucleotide incorporation activity. Mouse-derived Polß null fibroblasts had severely affected metabolic parameters. Indeed, gene knockout of Polß caused mitochondrial dysfunction, including reduced membrane potential and mitochondrial content. We show that Polß is a mitochondrial polymerase involved in mtDNA maintenance and is required for mitochondrial homeostasis.

4.
Klin Monbl Augenheilkd ; 226(9): 699-704, 2009 Sep.
Article in German | MEDLINE | ID: mdl-19750418

ABSTRACT

Retinal surgery of retinal detachment in the inferior part of the eye is often complicated by the development of proliferative vitreoretinopathy. Therefore the heavier-than-water concept using heavy silicone oils is a logical consequence for treatment of otherwise unsuccessful retinal surgery in such cases. While some surgeons already use heavy silicone oils in the clinical routine, others are carefully following complication rates. Even good anatomical and functional results are published as critical case reports. In this report we describe the advantages of the heavy silicone oil endotamponade and our own clinical experiences with Densiron(R) 68. The use of heavy silicone oils turned out to be quite convenient, leading for example to shorter tamponade times, easy handling of the oil, no need for uncomfortable prone-position of the patients. On the other hand one has to consider that Densiron(R) 68 is a mixture which contains 70 % PDMS and 30 % F 6 H8, a heavy fluid that was associated with multiple complications if used as sole long-term endotamponade. Based on these experiences we recommend all users bear in mind possible complications. However, such complications can be prevented.


Subject(s)
Retinal Detachment/therapy , Silicone Oils/chemistry , Silicone Oils/therapeutic use , Vitrectomy/methods , Vitreoretinopathy, Proliferative/therapy , Vitreous Detachment/therapy , Humans , Retinal Detachment/complications , Specific Gravity , Vitreoretinopathy, Proliferative/etiology , Vitreous Detachment/complications
5.
Eur J Ophthalmol ; 17(3): 327-31, 2007.
Article in English | MEDLINE | ID: mdl-17534811

ABSTRACT

PURPOSE: To evaluate and compare anterior chamber depth (ACD) measurements using Orbscan II (Bausch & Lomb, Rochester, NY) and IOLMaster (Carl Zeiss Meditec AG, Jena, Germany). METHODS: In this prospective clinical study, the authors measured ACD of 145 phakic eyes of 30 healthy volunteers and 115 patients using Orbscan II and IOLMaster. Average patient age was 52.9+/-19.4 (range 16 to 87) years. ACD was evaluated from corneal epithelium to anterior lens surface. Additionally, axial length (AL) was measured using the Zeiss IOLMaster to calculate the regression coefficient between AL and ACD. RESULTS: Mean ACD was 3.35+/-0.43 mm (range 2.01 mm to 4.37 mm) using Orbscan II and 3.36+/-0.41 mm (range 2.09 mm to 4.24 mm) using IOLMaster. Mean total axial length was 24.04 mm +/- 2.1 mm (range 20.7 mm to 31.41 mm). The linear regression coefficient of ACD between both methods was R=0.95. ACD and AL correlated only slightly (R=0.57). The Spearman coefficients of rank correlation were 0.94 and 0.61, respectively. A p value less than 0.01 (paired Wilcoxon test) was considered statistically significant. However, a significant difference was not calculated comparing ACD measurements using both systems and the Bland-Altman-Plot showed 95% of the differences ranging between 0.25 and -0.27 mm. CONCLUSIONS: Regarding clinical application, both systems seem to be equally good and interchangeable in clinical practice in terms of ACD evaluation.


Subject(s)
Anterior Chamber/anatomy & histology , Corneal Topography/methods , Diagnostic Techniques, Ophthalmological , Adolescent , Adult , Aged , Aged, 80 and over , Biometry , Humans , Middle Aged , Prospective Studies
6.
Ophthalmologe ; 103(10): 873-6, 2006 Oct.
Article in German | MEDLINE | ID: mdl-16855824

ABSTRACT

BACKGROUND: Aspherical intraocular lenses (IOLs) are presumed to optimize the optical characteristics of IOLs. In order to profit from these characteristics, exact calculation of the IOL power and good centration of the lens are essential. METHODS: In all, 43 eyes of 43 patients with an average age of 70.9+/-8.3 years underwent implantation of a Tecnis IOL (AMO, Ettlingen) after uneventful cataract surgery with topical anesthesia. IOL power calculation was performed using the Holladay, Haigis, and SRK II formulas. Spherical equivalent refraction and centration and position of the implanted IOLs were measured 6 months postoperatively. Centration of the IOL was analyzed using digital slit lamp photographs and an image analysis program. RESULTS: Best corrected visual acuity (BCVA) increased from 0.47+/-0.25 (LogMAR) preoperatively to 0.1+/-0.11 6 months postoperatively (spherical equivalent +0.3+/-0.6 D). The intraindividual difference between target refraction and achieved postoperative refraction was 0.64+/-0.11 D for the Holladay formula, -0.21+/-0.11 D for the Haigis formula, and 0.97+/-0.15 D for the SRK II formula. The mean decentration of the IOL from the center of the corneal limbus was 0.4+/-0.1 mm. CONCLUSIONS: For the aspherical Tecnis IOL very good postoperative functional results are reported, which are supported by an accurate calculation of the IOL power and a good centration of the IOL inside the capsular bag. In this study the Haigis formula showed the lowest difference between target refraction and achieved postoperative refraction.


Subject(s)
Equipment Failure Analysis/methods , Lenses, Intraocular , Prosthesis Fitting/methods , Refractometry/methods , Therapy, Computer-Assisted/methods , Vision Disorders/therapy , Aged , Equipment Design , Female , Humans , Male , Reproducibility of Results , Sensitivity and Specificity , Treatment Outcome , Vision Disorders/diagnosis
7.
Ophthalmologe ; 103(8): 667-72, 2006 Aug.
Article in German | MEDLINE | ID: mdl-16850290

ABSTRACT

Presbyopia represents the most common refractive error. There is currently no surgical treatment for presbyopia, which is effective, reliable, and safe. Excimer laser surgery has become a routine procedure for the correction of myopia, hyperopia, and astigmatism for years. Various treatment strategies for presbyopia have been brought forward using the excimer lasers. Besides monovision, creation of a multifocal cornea represents an attractive option. This procedure is also called "PresbyLASIK." Different ablation profiles to form a multifocal cornea are reviewed here and first clinical results are summarized."PresbyLASIK" is a new, interesting treatment strategy, with a huge potential for the future. At the present it should be used in controlled studies only because of some unsolved questions.


Subject(s)
Keratomileusis, Laser In Situ/instrumentation , Keratomileusis, Laser In Situ/methods , Practice Patterns, Physicians' , Presbyopia/diagnosis , Presbyopia/surgery , Surgery, Computer-Assisted/methods , Humans , Practice Guidelines as Topic
9.
Br J Ophthalmol ; 90(8): 971-4, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16687454

ABSTRACT

BACKGROUND: Owing to the improvement of modern intraocular lenses (IOLs) in terms of design and material, posterior capsule opacification (PCO) usually takes 2-3 years to develop. Thus, long term clinical evaluation of new implants is important. METHODS: As part of a prospective, non-randomised FDA trial, the Rayner Centerflex, a foldable hydrophilic acrylic, single piece IOL was implanted in one eye of 83 patients (mean age 73.5 (SD 7.0) years). Over 3 years postoperatively, a standardised FDA protocol concerning IOL safety and efficacy was followed including evaluation of spherical equivalent (SE), best corrected distance visual acuity (BCDVA), endothelial cell count (ECC), flare meter values, PCO development, and anterior capsule shrinkage. RESULTS: Postoperatively, mean SE was stable ranging between -0.3D and 0.17D. After 1-2 months, all patients achieved a BCDVA of 20/40 or better. At 3-6 months postoperatively, mean ECC decreased from 2612 (SD 346) cells/mm2 to 2380 (316) cells/mm2. Mean PCO score for the entire optic increased from 0.20 (0.20) months (3-6 months postoperatively) to 0.87 (0.57) resulting in a Nd:YAG rate of 29.41% after 3 years. No anterior capsule shrinkage was found. CONCLUSION: The Centerflex showed excellent functional results, low values for endothelial cell loss and inflammatory signs, and no anterior capsule shrinkage. PCO formation was higher compared to other IOLs, which could be explained by the incomplete sharp edge at the optic-haptic junctions representing an "Achilles' heel" for cell ingrowth.


Subject(s)
Lenses, Intraocular , Acrylic Resins , Aged , Aged, 80 and over , Biocompatible Materials , Cataract/etiology , Endothelial Cells/pathology , Female , Follow-Up Studies , Humans , Laser Therapy , Lens Capsule, Crystalline/pathology , Lens Capsule, Crystalline/surgery , Male , Materials Testing , Middle Aged , Postoperative Complications , Prospective Studies , Prosthesis Design , Recurrence
10.
Ophthalmologe ; 101(6): 600-3, 2004 Jun.
Article in German | MEDLINE | ID: mdl-15197576

ABSTRACT

PURPOSE: In the past 50 years the IOL has been improved. Nowadays it is possible to exactly calculate the necessary IOL power and correct toric refractive errors. In this study we developed methods for measuring rotation and decentration using the example of a hydrophilic acrylic IOL. METHODS: Following cataract surgery, the first retroilluminated photograph was taken. The position of the IOL was determined with the image analysis program Adobe Photoshop. RESULTS: Measurement of a rotational movement or of a decentration of an IOL can be done accurately and rapidly. Evaluation of the stability of rotation of the hydrophilic acrylic IOL measured here showed an average rotation of the IOL of 5.3+/-1.4 degrees after 6 months compared to the position directly after implantation. CONCLUSION: The measurement methods presented here are easy to use and provide reliable results. Examiners must have basic knowledge of the computer programs used. Also, these methods depend on good quality of the retroilluminated photographs.


Subject(s)
Cataract/pathology , Image Interpretation, Computer-Assisted/methods , Lens Implantation, Intraocular/methods , Lenses, Intraocular , Photography/methods , Surgery, Computer-Assisted/methods , Cataract Extraction , Humans , Rotation
11.
Ophthalmologe ; 99(11): 811-4, 2002 Nov.
Article in German | MEDLINE | ID: mdl-12430031

ABSTRACT

BACKGROUND: The potentially accommodative intraocular lens (IOL) is a new development in IOL design METHODS: We evaluated the new Humanoptics 1CU accommodative IOL in a laboratory study with human post mortem autopsy eyes. Using the Miyake-Apple posterior view video technique, the movement pattern of the IOL was tested and observed from the posterior perspective. RESULTS. A circular bend at the level of the ciliary body applied slight circular force onto the sclera allowing the relaxation of the zonules. The shift of focus was demonstrated by using a reading target. In addition, viscoelastic was injected into the vitreous resulting in the same anterior movement of the IOL optic. CONCLUSIONS: The 1CU Humanoptics accommodative IOL showed potential accommodative behaviour in the laboratory. The accommodative (respectively pseudoaccommodative) effect was based on the anterior shift principle with anterior movement of the IOL-optic in the state of relaxing zonules. Whether this reflects the clinical situation, especially to this extent, must be further evaluated.


Subject(s)
Accommodation, Ocular , Lens Implantation, Intraocular , Lenses, Intraocular , Autopsy , Cataract Extraction , Ciliary Body , Humans , Movement , Prosthesis Design , Video Recording
12.
Ophthalmologe ; 99(11): 815-9, 2002 Nov.
Article in German | MEDLINE | ID: mdl-12430032

ABSTRACT

BACKGROUND: Changes in the anterior chamber depth (ACD) after pilocarpin application are generally regarded as reflecting an accommodative effect of accommodative intraocular lenses (IOLs) METHODS: We implanted Humanoptics 1CU accommodative IOLs into 25 eyes of 20 patients aged 53.2+/-14.7 years (range: 30-83 years). In seven of these patients, we were able to measure anterior chamber depth changes after the application of pilocarpine (2%) eye drops 3 months postoperatively using a Zeiss IOLMaster, an Orbscan II topography system, as well as by ultrasound biomicroscopy (20 MHz-US-head). RESULTS: Uncorrected near acuity was on average 0.4+/-0.23 (0.1-0.8) and uncorrected distance acuity was 0.76+/-0.23 (0.3-1). Before pilocarpine, ACD was 3.19+/-2.11 mm (IOL-Master), 3.35+/-2.22 mm (Orbscan II) and 3.35+/-2.21 mm (US-biomicroscopy) ( P=0.96). After pilocarpine, ACD was 2.61+/-1.71 mm (IOL-Master), 2.63+/-1.78 mm (Orbscan II) and 3.15+/-2.08 mm (US-biomicroscopy) ( P=0.002). The average individual ACD change before/after pilocarpine was 0.83+/-0.25 mm with the IOL-Master, 1.04+/-0.39 mm with the Orbscan II System and 0.28+/-0.14 with US-biomicroscopy ( P=0.0004). DISCUSSION: The 1CU Humanoptics accommodative IOL presented with potential accommodative capabilities in clinical evaluation. Drug induced accommodation by pilocarpine does not reflect real accommodative effects. The differences in ACD measurements between three different methods were statistically significant. Evaluation methods for accommodative IOLs should be carefully analysed and further development of objective means for evaluation is needed.


Subject(s)
Accommodation, Ocular , Aged, 80 and over , Anterior Chamber , Lens Implantation, Intraocular , Lenses, Intraocular , Adult , Aged , Anterior Chamber/anatomy & histology , Data Interpretation, Statistical , Follow-Up Studies , Humans , Middle Aged , Miotics/pharmacology , Pilocarpine/pharmacology , Prosthesis Design , Time Factors , Ultrasonography
14.
Nat Genet ; 25(3): 329-32, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10888884

ABSTRACT

Syndecan-1 is a cell-surface, heparan-sulphate proteoglycan (HSPG) predominantly expressed by epithelial cells. It binds specifically to many proteins, including oncoproteins. For example, it induces the assembly of a signalling complex between FGF ligands and their cognate receptors. But so far there has been no direct evidence that this proteoglycan contributes to tumorigenesis. Here we have examined the role of syndecan-1 (encoded by Sdc1) during mammary tumour formation in response to the ectopic expression of the proto-oncogene Wnt1. We crossed syndecan-1-deficient mice with transgenic mice that express Wnt1 in mammary gland (TgN(Wnt-1)1Hev; ref. 2). Ectopic Wnt-1 expression induces generalized mammary hyperplasia, followed by the development of solitary tumours (median time 22 weeks). We show that in Sdc1-/- mice, Wnt-1-induced hyperplasia in virgin mammary gland was reduced by 70%, indicating that the Wnt-1 signalling pathway was inhibited. Of the 39 tumours that developed in a test cohort of mice, only 1 evolved in the Sdc1-/- background. In addition, we show that soluble syndecan-1 ectodomain purified from mouse mammary epithelial cells stimulates the activity of a Wnt-1 homologue in a tissue culture assay. Our results provide both genetic and biochemical evidence that syndecan-1 can modulate Wnt signalling, and is critical for Wnt-1-induced tumorigenesis of the mouse mammary gland.


Subject(s)
Heparan Sulfate Proteoglycans/metabolism , Mammary Neoplasms, Experimental/physiopathology , Membrane Glycoproteins/metabolism , Proteoglycans/metabolism , Proto-Oncogene Proteins/metabolism , Zebrafish Proteins , Animals , Female , Heparan Sulfate Proteoglycans/genetics , Heparan Sulfate Proteoglycans/physiology , Male , Mammary Glands, Animal/growth & development , Mammary Glands, Animal/pathology , Mammary Glands, Animal/physiology , Membrane Glycoproteins/genetics , Membrane Glycoproteins/physiology , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Proteoglycans/genetics , Proteoglycans/physiology , Proto-Oncogene Proteins/biosynthesis , Proto-Oncogene Proteins/genetics , Syndecan-1 , Syndecans , Wnt Proteins , Wnt1 Protein
15.
Oncol Rep ; 7(1): 131-3, 2000.
Article in English | MEDLINE | ID: mdl-10601606

ABSTRACT

We investigated the ischemia-reperfusion-induced tumour growth delay as a function of ischemic time, tumour temperature, and the amount of inspired oxygen during reperfusion. The rhabdomyosarcoma R1H growing on the right flank of male WAG/Rij rats was clamped for 2 or 4 h at 20 degrees C or 37 degrees C. Five minutes prior to and 10 min during reperfusion the animals respired air, pure oxygen or carbogen (95% O2, 5% CO2). Comparison of single treatment modalities with untreated controls revealed significant tumour growth delays after clamping times of 4 h at 37 degrees C for air and pure oxygen, but not for carbogen.


Subject(s)
Ischemia/pathology , Oxygen/pharmacology , Rhabdomyosarcoma/blood supply , Animals , Carbon Dioxide/pharmacology , Cell Division , Male , Rats , Rats, Inbred Strains , Reperfusion , Rhabdomyosarcoma/pathology
16.
J Cell Sci ; 112 ( Pt 1): 97-110, 1999 Jan.
Article in English | MEDLINE | ID: mdl-9841907

ABSTRACT

The zebrafish egg provides a useful experimental system to study events of fertilization, including exocytosis. We show by differential interference contrast videomicroscopy that cortical granules are: (1) released nonsynchronously over the egg surface and (2) mobilized to the plasma membrane in two phases, depending upon vesicle size and location. Turbidometric assay measurements of the timing and extent of exocytosis revealed a steady release of small granules during the first 30 seconds of egg activation. This was followed by an explosive discharge of large granules, beginning at 30 seconds and continuing for 1-2 minutes. Stages of single granule exocytosis and subsequent remodeling of the egg surface were imaged by either real-time or time-lapse videomicroscopy as well as scanning electron microscopy. Cortical granule translocation and fusion with the plasma membrane were followed by the concurrent expansion of a fusion pore and release of granule contents. A dramatic rearrangement of the egg surface followed exocytosis. Cortical crypts (sites of evacuated granules) displayed a purse-string-like contraction, resulting in their gradual flattening and disappearance from the egg surface. We tested the hypothesis that subplasmalemmal filamentous (F-) actin acts as a physical barrier to secretion and is locally disassembled prior to granule release. Experimental results showed a reduction of rhodamine-phalloidin and antimyosin staining at putative sites of secretion, acceleration of the timing and extent of granule release in eggs pretreated with cytochalasin D, and dose-dependent inhibition of exocytosis in permeabilized eggs preincubated with phalloidin. An increase in assembled actin was detected by fluorometric assay during the period of exocytosis. Localization studies showed that F-actin and myosin-II codistributed with an inward-moving, membrane-delimited zone of cytoplasm that circumscribed cortical crypts during their transformation. Furthermore, cortical crypts displayed a distinct delay in transformation when incubated continuously with cytochalasin D following egg activation. We propose that closure of cortical crypts is driven by a contractile ring whose forces depend upon dynamic actin filaments and perhaps actomyosin interactions.


Subject(s)
Actin Cytoskeleton/metabolism , Actins/metabolism , Cytoplasmic Granules/metabolism , Exocytosis/physiology , Myosins/metabolism , Ovum/metabolism , Actin Cytoskeleton/drug effects , Animals , Cytochalasin D/pharmacology , Dose-Response Relationship, Drug , Fluorescent Dyes/metabolism , Microscopy, Interference , Microscopy, Video , Phalloidine/pharmacology , Time Factors , Zebrafish
17.
J Med ; 28(5-6): 387-92, 1997.
Article in English | MEDLINE | ID: mdl-9604797

ABSTRACT

An important and frequently overlooked cause of leg ulcers are cholesterol emboli. A 79-year-old woman with a non-healing leg ulcer is described. The diagnosis of cholesterol embolism was made with the aid of a deep biopsy of the ulcer and serial sectioning of the specimen. This report serves to illustrate the importance of considering cholesterol embolism when evaluating a chronic leg ulcer, and the diagnostic value of proper biopsy techniques.


Subject(s)
Embolism, Cholesterol/complications , Leg Ulcer/etiology , Aged , Biopsy/methods , Female , Humans , Leg Ulcer/pathology , Leg Ulcer/physiopathology , Wound Healing/physiology
18.
N Engl J Med ; 335(3): 209-10; author reply 210-1, 1996 Jul 18.
Article in English | MEDLINE | ID: mdl-8657233
19.
Mol Reprod Dev ; 43(4): 536-47, 1996 Apr.
Article in English | MEDLINE | ID: mdl-9052946

ABSTRACT

Actin and nonmuscle myosin heavy chain (myosin-II) have been identified and localized in the cortex of unfertilized zebrafish eggs using techniques of SDS-polyacrylamide gel electrophoresis, immunoblotting, and fluorescence microscopy. Whole egg mounts, egg fragments, cryosections, and cortical membrane patches probed with rhodamine phalloidin, fluorescent DNase-I, or anti-actin antibody showed the cortical cytoskeleton to contain two domains of actin: filamentous and nonfilamentous. Filamentous actin was restricted to microplicae and the cytoplasmic face of the plasma membrane where it was organized as an extensive meshwork of interconnecting filaments. The cortical cytoplasm deep to the plasma membrane contained cortical granules and sequestered actin in nonfilamentous form. The cytoplasmic surface (membrane?) of cortical granules displayed an enrichment of nonfilamentous actin. An antibody against human platelet myosin was used to detect myosin-II in whole mounts and egg fragments. Myosin-II colocalized with both filamentous and nonfilamentous actin domains of the cortical cytoskeleton. It was not determined if egg myosin was organized into filaments. Similar to nonfilamentous actin, myosin-II appeared to be concentrated over the surface of cortical granules where staining was in the form of patches and punctate foci. The identification of organized and interconnected domains of filamentous actin, nonfilamentous actin, and myosin-II provides insight into possible functions of these proteins before and after fertilization.


Subject(s)
Actins/metabolism , Myosins/metabolism , Ovum/metabolism , Animals , Cytoskeleton , Electrophoresis, Polyacrylamide Gel , Female , Fluorescent Antibody Technique, Indirect , Immunoblotting , Ovary/metabolism , Ovum/ultrastructure , Zebrafish
20.
Mol Reprod Dev ; 32(3): 217-28, 1992 Jul.
Article in English | MEDLINE | ID: mdl-1497871

ABSTRACT

The sperm entry site (SES) of zebrafish (Brachydanio rerio) eggs was studied before and during fertilization by fluorescence, scanning, and transmission electron microscopy. Rhodamine phalloidin (RhPh), used to detect polymerized filamentous actin, was localized to microvilli of the SES and to cytoplasm subjacent to the plasma membrane in the unfertilized egg. The distribution of RhPh staining at the SES correlated with the ultrastructural localization of a submembranous electrondense layer of cortical cytoplasm approximately 500 nm thick and containing 5- to 6-nm filaments. Actin, therefore, was organized at the SES as a tightly knit meshwork of filaments prior to fertilization. Contact between the fertilizing sperm and the filamentous actin network was observed by 15-20 sec postinsemination or just before the onset of fertilization cone formation. Growing fertilization cones of either artificially activated or inseminated eggs exhibited intense RhPh staining and substantial increase in thickness of the actin meshwork. Collectively, TEM and RhPh fluorescence images of inseminated eggs demonstrated that the submembranous actin became rearranged in fertilization cones to form a thickened meshwork around the sperm nucleus during incorporation. The results reported here suggest that activation of the egg triggers a dramatic polymerization of actin beneath the plasma membrane of the fertilization cone. Furthermore, the actin involved in sperm incorporation is sensitive to the action of cytochalasins.


Subject(s)
Actin Cytoskeleton/ultrastructure , Actins/analysis , Oocytes/ultrastructure , Sperm-Ovum Interactions , Zebrafish/physiology , Animals , Cytoplasm/ultrastructure , Female , Male , Microscopy, Electron/methods , Microvilli/ultrastructure
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