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Biomedical subjects

A Vassiliadis

Publications and source records attributed to A Vassiliadis.

At least 19 recordsLinked to original sources
PubMed1995

[Benign lesions of the thyroid. Clinical methodology++ and therapeutic management in our personal experience].

Thyroid benign nodules are common (90-95%). A personal series of 544 cases forms the basis for a discussion of modern diagnostic techniques, their value and limitations. At the present time, subtotal or near total thyroidectomy is preferred, also in benign thyroid disease. The perfect anatomical knowledge of the neck is of paramount importance to minimize the risk of complications, such as a superior or inferior laryngeal nerve injury and hypoparathyroidism. Temporary suclinic, clinic, definitive hypoparathyroidism was never observed. Relapse was observed in 20 hypothyreosic patients with hormonal therapy.

Adult↗
PubMed1992

Transcanalicular THC:YAG dacryocystorhinostomy.

Chromium-sensitized and thulium- and holmium-doped YAG lasers (THC:YAG laser) were used to create a nasal bony ostium in the area of the lacrimal sac fossa in four fresh frozen bisected human cadaver heads. The lasers-long pulsed (300 milliseconds), compact, self-contained, and solid state--operate in the near infrared (2.1 microns). The opening was created by passing the 320-micrometer laser fiber across the canalicular system. Pulse energies of 250 to 900 mJ were used with a repetition rate of 5 to 15 pulses per second. Energy levels ranging from 1.25 to 9 W produced a full-thickness bony ostium approximately 3 to 4 mm in diameter. Silicone tubing was then threaded through the superior and inferior canaliculus system in the standard fashion. This technique may simplify conventional dacryocystorhinostomy as well as endonasal laser dacryocystorhinostomy procedures.

Dacryocystorhinostomy↗
PubMed1991

Lysosomal cobalamin accumulation in fibroblasts from a patient with an inborn error of cobalamin metabolism (cblF complementation group): visualization by electron microscope radioautography.

Cobalamin (Cbl, vitamin B12) bound to transcobalamin II (TCII) enters cultured fibroblasts by receptor-mediated endocytosis. Following degradation of the TCII, Cbl is subsequently found in either the cytoplasm bound to methionine synthase or in the mitochondria bound to methylmalonyl CoA mutase. In fibroblasts from patients belonging to the cblF complementation group, Cbl is found free in the cell and is not transferred to the above two target enzymes. Quantitative EM radioautography was utilized to visualize intracellular Cbl in fibroblasts from cblF patients and from normal subjects. In cblF cells, 60% of all silver grains were assigned to lysosomes, with only 12.6% over cytoplasm and 1.2% over mitochondria. In contrast, in control cells, only 4.7% were assigned to lysosomes, with 47% to cytoplasm and 23.4% to mitochondria. Subcellular fractionation showed that in cblF cells, the majority of label was associated with clearly recognizable lysosomes. These studies conclusively demonstrate that secondary lysosomes accumulate Cbl in cblF disease.

Autoradiography↗
PubMed1991

Subconjunctival THC:YAG laser thermal sclerostomy.

A THC:YAG laser (thulium, holmium, chromium-doped YAG crystal) was used to create thermal sclerostomies in 21 glaucomatous eyes of 19 patients. The laser is a long-pulsed (300 microsec), compact, self-contained, solid state laser operating in the near infrared (2.1 mu). A 1-mm conjunctival stab incision was made 12 mm away from the sclerostomy site to allow entry of a specially designed 22-gauge (712 mu) optic probe that delivers energy at a right angle to the long axis of the fiber. Probe insertion produced minimal disturbance of the conjunctiva. Pulse energies of 80 mJ to 120 mJ were used with a repetition rate of 5 pulses/second. Total energy levels to produce full-thickness sclerostomies ranged from 1.4 to 4.8 J. Subconjunctival 5-fluorouracil injections were administered in 15 eyes. At 3 months the mean intraocular pressure of successful cases (16) was 14 mmHg (range, 9 to 22 mmHg). Of successful cases, the mean intraocular pressure at 6 months was 13 mmHg (range, 2 to 22 mmHg). Five cases failed within the initial 3 months, and 3 additional cases failed by 6 months. The authors conclude that this full-thickness sclerostomy technique may simplify filtering surgery without anterior chamber instrumentation and with minimal conjunctival trauma.

Adult↗
PubMed1991

A new contact neodymium:YAG laser for cyclophotocoagulation.

A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.

Animals↗
PubMed1990

Subconjunctival THC: YAG laser limbal sclerostomy Ab externo in the rabbit.

A chromium-sensitized, and thulium and holmium-doped YAG laser (THC:YAG laser) was used to create bilateral limbal sclerostomies in six Dutch pigmented rabbits. The laser is a long-pulsed (300 microseconds) [corrected], compact, self-contained, solid-state laser operating in the near infrared (2.1 microns). A 1-mm conjunctival stab incision was made 12 mm away from the sclerostomy site to allow entry of a specially designed 26-gauge (480 microns) optic probe that delivers energy at right angles to the long axis of the fiber. Probe insertion minimally disturbed the conjunctiva. Pulse energies of 60 to 150 mJ were used with a repetition rate of 5 pulses/s. Energy levels ranging from 1.35 to 6.6 J produced full-thickness sclerostomies. Histopathology showed a sharply defined perforating limbal wound at all energy levels. The overlying conjunctiva was intact, with swelling of the adjacent cornea. A peripheral iridectomy was intentionally created with the laser through the peripheral limbus, resulting in a sharply defined perforating tract through the iris/ciliary body. This technique may simplify filtering sclerostomy surgery, without anterior chamber instrumentation and with minimal conjunctival trauma.

Animals↗
PubMed1988

Three-dimensional computed tomography for maxillofacial surgery: report of cases.

Methods of three-dimensional analysis of axial computed tomographic images have recently been described. Mostly, reports have concentrated on applications relative to congenital deformities. In this report, one method of three- dimensional reformatting is reviewed. Images formed by this method have solid surface appearance and can be color enhanced and manipulated to isolate anatomic structures of interest. The program allows mathematical quantitation of tissue densities, volumes, and distances. Furthermore, models and implants can be easily made using the programs CAD-CAM ability. These images and models can be generated from data obtained on the most common CT units without any modifications. This report emphasizes maxillofacial applications other than those previously reported in the surgical and radiological literature.

Adult↗
PubMed1986

Perspective: three-dimensional imaging of the musculoskeletal system.

An evaluation of musculoskeletal disorders in 202 patients using three-dimensional CT displays has revealed the usefulness of the technique, especially in patients with fractures of skeletal areas with complex anatomy, articular disorders of the hip, and spinal stenosis. In some cases, plastic models of diseased areas have been created from the CT data and are reasonably accurate, providing a graphic representation of the disease and the ability to perform rehearsal surgery. A preliminary investigation of three-dimensional displays of MR images indicates that the technique is feasible, although its clinical practicality requires further analysis.

Fractures, Bone↗
PubMed1986

Three-dimensional imaging of bone from computerized tomography.

An automatic computer technique was designed to produce three-dimensional (3D) images of bony anatomy on a cathode ray tube (CRT) from computerized tomography (CT) data. The authors transferred CT scan data of a cadaver and 11 patients to a computer system via magnetic tape. An automatic edge extraction algorithm generated an outline of bone specified by a range of CT numbers for each scan slice. These outlines were stacked in the computer and various graphics options used to represent the 3D anatomy of bone on a high-resolution CRT screen. The 3D image data were interfaced with a three-axis computer numerically controlled milling device to produce solid models of these bone images. Comparison of the dimensions of the solid models of the femur, hemipelvis, and femoral medullary canal to the actual cadaver specimen demonstrated that the models were accurate in size to within 1-3 mm. These 3D images and solid models will be helpful for preoperative diagnosis, surgical planning, and customized prosthesis manufacture in complex orthopaedic cases.

Bone and Bones↗
PubMed1985

Three-dimensional imaging of the ankle joint from computerized tomography.

A computer system was developed to rapidly reconstruct three-dimensional (3D) images of bone from computerized tomography scans of the ankle joint. Solid models of the bones were produced from the 3D image data through the use of a computer numerically controlled milling machine. A cadaver ankle joint was scanned, and models of the distal tibia and fibula and dome of the talus were made and compared to the actual bone specimens. The measurements of the models were within 3 mm or less of the bones in all three planes (average, 1.2 mm or 5.5%). These 3D images and models of bone should allow better visualization of joint pathology and a system for preoperative planning on exact bone models to optimize the results of surgery.

Ankle Joint↗
PubMed1985

Three dimensional imaging of bone from analysis of computed tomography data.

A computer system was developed to reconstruct three dimensional images of bone from analysis of computed tomography data. Images of bone can be made within minutes and rotated for viewing from any direction. An editing process allows visualization of the articular surfaces of any joint. Solid models of the bone images can be produced with an accuracy of 1 mm to 3 mm by interfacing the image data with a computer numerically controlled milling machine. This technology will provide better information to the surgeon for preoperative diagnosis and planning and for the design of customized implants.

Adult↗
PubMed1981

Retinal injury due to industrial laser burns.

Ocular industrial lasers burns in seven patients were analyzed as to cause, severity, and type of injury. Ocular damage ranged from minimal retinal burns to extensive areas of damage with commotio retinae and vitreous hemorrhage. Visual loss ranged from complete recovery without residual defect to a profound decrease in central acuity. The kinds of lasers causing these injuries were neodymium YAG, argon, krypton, and rhodamine dye. Severity of injury was related to several factors. Some degree of carelessness was involved in all injuries.

Accidents, Occupational↗
PubMed1977

Lysinoalanine formation in wool after treatments with some phosphate salts.

Treatment of wool with solutions of sodium tripolyphosphate, potassium tetrapyrophosphate, and sodium phosphate results in the formation of lysinoalanine, the amount of which increases from the first to the last reagent. As this may be due to the different pH, solutions of the three salts of the same pH were also tried. This series of experiments suggests that although the hydroxyl ions contribute to the formation of lysinoalanine, the governing factor is the kind of the anions concerned, as the sodium phosphate acts in a more rigorous may than the two other salts, in spite of the smaller concentration and the faster reduction of the pH of the solution during treatment.

Alanine↗
PubMed1976

Techniques of argon laser photocoagulation of diabetic disk new vessels.

Four argon laser techniques have been evaluated in the eradication of diabetic disk neovascularization: focal (nonfeeder) photocoagulation, feeder-frond photocoagulation alone, panretinal photocoagulation alone, and feeder-frond treatment combined with panretinal photocoagulation. Focal photocoagulation was dangerous and the least effective technique in preventing recurrence of neovascularization. Feeder-frond photocoagulation was effective initially, but was associated with a high incidence of recurrent neovascularization. Panretinal photocoagulation and panretinal photocoagulation combined with feeder-frond treatment produced results superior to those obtained with the two earlier techniques. The best results were obtained with combined feeder-frond and panretinal photocoagulation done concurrently. Early diagnosis, aggressive photocoagulation therapy, and close follow-up were essential in order to obtain good results.

Adolescent↗