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At least 1,693 records · Page 94Linked to original sources
PubMed2003

Blood vascular architecture of the palatine tonsil in the musk shrew (Suncus murinus): scanning electron microscopic study of corrosion casts.

The musk shrew, Suncus murinus, is one of the primitive mammals and has a pair of palatine tonsils. In the present study, we investigated the blood microvascular architecture of the tonsil in this animal by scanning electron microscopy of corrosion casts. The paranodular arterioles entered the lymph nodule to form a coarse capillary plexus within the nodule. Some of the arterioles reached the dome region to give rise to a fine meshwork of dome subepithelial capillaries. This dome subepithelial capillary network did not show any hairpin or switch-back patterns, as seen in human and rabbit tonsils. Both of the nodular and dome capillaries were drained into the postcapillary venules in the periphery of the nodular or the paranodular region. On the surface of these cast venules, oval-shaped indentations were seen corresponding to the luminal surface of the high endothelial venules. These venules were collected into the large vein at the bottom of the tonsil. The blood vascular architecture of the musk shrew tonsil is basically the same as those of other mucosa-associated lymphoid tissues in mammals.

Animals↗
PubMed2001

The influence of ultrasound on the retention of cast posts cemented with different agents.

AIM: The aim of this study was to evaluate the influence of ultrasound during the removal of posts cemented with either zinc phosphate cement, glass ionomer cement or resin cement. METHODOLOGY: Eighty-four single-rooted teeth were prepared and after cementation of cast posts, they were randomly divided into six groups of 14. Group 1, 2 and 3 did not receive ultrasonic vibration, whilst groups 4, 5 and 6 received ultrasonic vibration for 10 min. The force necessary for post removal was determined using a universal testing machine. Results were statistically analysed using ANOVA and Tukey tests (5%). RESULTS: The application of ultrasonic vibration reduced the retention provided by zinc phosphate and glass ionomer cements by 39% and 33%, respectively. CONCLUSIONS: A statistically significant reduction in the force necessary to remove posts cemented with zinc phosphate and glass ionomer cements occurred following application of ultrasound. The application of ultrasonic vibration did not influence the retention of cast posts cemented with resin cement.

Analysis of Variance↗
PubMed1999

Effect of anticoagulation and lavage prior to casting of postmortem material with Mercox and Batson 17.

In this study we compare the quality of vascular casts, obtained from organs of several animal species from different sources and sacrificed under different conditions. Organs from healthy animals were injected with two different polymers such as Mercox and Batson No. 17. When the specimens were observed under a scanning electron microscope structural elements such as endothelial nuclear impressions on vessels and capillaries, endothelial cell borders, venous valves, imprints of smooth muscle cells and intra-arterial cushions were identified. Organs excised post mortem from large animals can be used for microvascular corrosion casting studies with optimal results.

Animals↗
PubMed1999

Finite element analysis of the effect of vertical curvature on half-oval cast clasps.

High stresses in half-oval cast clasps are the main causes of deformation or fracture. A vertical curvature in clasps is said to be effective in reducing stress. However, such claims lack scientific basis. The purpose of the present study was to evaluate stress and stiffness in a three-dimensional (3D) finite element analysis (FEA) model of clasps with different vertical curvatures, cross-sectional forms and tapers, and to clarify the effect of vertical curvature on the half-oval cast clasp. Circumferential clasp arms for the mandibular second premolar were analysed by 3D FEA. The clasp arms were approximated by curved cantilever beams with a half-oval cross-section around a cylinder. The radius of curvature was set at 4 mm and the angle subtended by the clasp arm was 120 degrees. The clasp tip was set at a point 2 mm lower than the base. In the 'No-taper' half-oval clasp arm, stress increased and stiffness decreased with the increase in vertical curvature. In the shape of a preformed wax pattern (thickness/width = 0.80, tip/base = 0.70), stress and stiffness decreased slightly. In an 'Original' form (thickness/width = 0.33, tip/base = 0.80), vertical curvature had a very slight effect on stress and stiffness, and stress was the lowest. These findings suggest the superiority of the 'Original' form, with less stress and no effect of vertical curvature.

Dental Casting Technique↗
PubMed2002

Marginal adaptation of partial crowns cast in pure titanium and in a gold alloy - an in vivo study.

The aim of the present study was to assess in vivo the marginal integrity of partial crowns cast in pure titanium and in a gold alloy. For this purpose, two groups of 25 molars were prepared for partial crowns and then restored with partial crowns cast in Degulor M gold alloy and in pure titanium. At a subsequent session, replicas were produced using a special impression-taking technique. The scanning electron microscope (SEM) technique was used to perform quantitative margin analysis (Tiffmess 1.8 program). The gold alloy partial crowns displayed significantly (P < 0.05) more continuous margin (marginal quality A, <50 microm), and the titanium partial crowns significantly more marginal quality B (50-100 microm) and C (>100 microm). The results show that better marginal integrity can be achieved with gold alloy than with titanium partial crowns. However, in practical terms the difference in marginal quality is only slight, so that the use of pure titanium for single-tooth restorations is justified.

Cementation↗
PubMed2002

Radiological examination of dental castings -- a review of the method and comparisons of the equipment.

The mechanical stability of crowns or bridges as well as frameworks for removable partial dentures depends on factors like thickness and metal structure. The biological compatibility can be influenced by porosities and soldered joints. Radiological testing is a non-destructive method to check defects in dental castings. As dental precious metal alloys have high X-ray absorption, testing of high gold alloys should be performed with a suitable X-ray machine at a tube voltage of 120 kV since the X-ray penetration of dental X-ray units using a tube voltage of 70 to 80 kV is not high enough for these alloys. As the absorption of Co-Cr alloys and of titanium is much lower, these materials can be tested with a dental X-ray apparatus. The radiographs show location and size of metal defects. They enable an examination of metal thickness and content of porosities. Metal defects reducing the biological compatibility or cast stability can be detected prior to clinical fitting.

Absorption↗
PubMed2002

[August Schummer (1902-1977): breaking ground for new corrosion casting anatomy].

About 70 years ago, when the so-called polymeric science succeeded in producing synthetic materials and making it available to industrial manufacturing, August Schummer intuitively recognized and reconnoitred the use of these new materials for corrosion casting anatomy. Through the employment of this method, which was named after him, an epoch-making step was achieved in the anatomy of corrosion casting. In the year that followed there has been a very successful progress in the exploration of blood vessels right through into the capillaries of the organs. On the occasion of the 100th birthday of August Schummer (born 13th of December 1902 in Sălişte near Hermannstadt, died 1st of March 1977 in Giessen), former Professor of Veterinary Anatomy at the Universität Giessen, we commemorate the life and work of this exceptionally talented and passionate anatomist.

Anatomy, Veterinary↗
PubMed2002

Vasculature of the ophthalmic rete in night herons (Nycticorax nycticorax): scanning electron microscopy of corrosion casts.

Vasculature of the ophthalmic rete (rete ophthalmicum) in the night heron (Nycticorax nycticorax) was studied using scanning electron microscopy of vascular corrosion casts and light microscopy on tissue sections. Most blood to the eyeball and a lesser volume of blood to the brain passed through the ophthalmic rete via the external ophthalmic artery. The collateral retial arterioles originated from the external ophthalmic artery forming a flat and fusiform-shaped arterial network at the ventrotemporal region of the eyeball. The arterial network was intermixed with a similar complex of the veins from the eye. The ophthalmotemporal artery, which supplied the eyeball posteriorly, and supraorbital and infraorbital arteries, which supplied the eyeball anteriorly, originated from the rete. Blood from the eye, which is a site of potential heat loss, drained into the ophthalmic rete via the ophthalmotemporal vein. On the casts of retial arterioles, slit-like cleavages at branching sites representing flap valves, which might play a role as sluice valves, were seen. In addition, marks of circularly running grooves, which might represent tufts of smooth muscle cells and might contribute to a sphincter activity, were observed. These anatomical specializations of the avian ophthalmic rete, involving parallel arrangement of arteries and veins, may function to facilitate counter-current heat exchange and to regulate blood pressure and volume to the eye and the brain.

Animals↗
PubMed2001

Skin irritation and exposure to diisocyanates in orthopedic nurses working with soft casts.

BACKGROUND: Diisocyanates are widely used in industry, for example at hospitals as a constituent of Scotch Cast soft casts (3M, Glostrup, Denmark). They are a cause of occupational asthma and have been described as causing cutaneous problems both as irritants and as sensitizers. OBJECTIVE: The sensitizing potential of diisocyanates has previously only sporadically been described, predominantly in case reports. Therefore, we conducted this study to investigate eventual work-related skin sensitization to diisocyanates in a regularly exposed population. METHODS: The nursing staff of an orthopaedic outpatient clinic, consisting of 10 persons, were interviewed and subjected to patch testing using 5 types of diisocyanates and the TRUE Test (ECDRG Standard Series) to elucidate possible other type IV allergies with similar symptoms. Patch test results were evaluated according to the guidelines of the International Contact Dermatitis Group. RESULTS: We found no relationship between exposure time and severity of symptoms. Symptoms were mild, consisting of redness, itching, or both, lasting about 30 minutes. There was no suggestion that they result in any chronic skin problems. One nurse presented a doubtful reaction towards diaminophenylmethane (MDA) and isophorene diisocyanate (IPDI). Nine persons had no reactions to the 5 diisocyanates used in the patch test. Positive reactions were seen to nickel (4/10), thiomersal (2/10), and perfume mix (1/10). CONCLUSION: Our observations suggest that diisocyanates are primarily irritants rather than sensitizers in the professional setting studied. The skin symptoms of irritation were all mild and temporary.

Adult↗
PubMed1999

Scaphoid fracture displacement with forearm rotation in a short-arm thumb spica cast.

Three-dimensional motion between the fragments of an experimental scaphoid waist fracture was measured during dynamic forearm pronation and supination in a short-arm thumb spica cast with and without applied tendon loads. Metal markers placed in each fragment were tracked using high-speed biplane radiographic image sequences and stereophotogrammetric analysis. Peak displacements (from the intact state) exceeded 1 mm in all specimens, with the largest movements occurring in the radial direction during pronation (mean: 2.1 mm unloaded, 2.5 mm loaded). Total range of displacement motion between fragments exceeded 3 mm (mean ulnar/radial direction: 3.4 mm unloaded, 4.1 mm loaded). Dorsal/palmar and proximal/distal displacements were minimal except at the extremes of forearm pronation/supination. Rotations between fragments were small (within +/- 6 degrees) and varied considerably across specimens. No significant differences were found between loaded and unloaded trials. Thus, in the absence of long-arm thumb spica casting to limit forearm rotation, significant motion between the fragments of a scaphoid waist fracture is likely.

Biomechanical Phenomena↗
PubMed2001

[Mechanical stimulation of venous blood flow in below-the-knee plaster cast].

Physical methods became recently more important as an alternative to anticoagulation for prophylaxis of thromboembolism and were studied for their efficacy. The AV-impulse-system proved efficient in reducing thromboembolic complications in patients undergoing hip surgery by increasing the return of venous blood in the deep veins of the leg. In a preclinical trial we studied the influence of the AV-impulse-system and of active forefoot movement on venous blood return in 12 lower extremities of 6 healthy individuals immobilized in below the knee plaster casts. Our results show a significant increase in venous blood flow caused by the AV-impulse-system (p < 0.05) and by active forefoot movements (p < 0.05). Prevention of thromboembolic complications in trauma and orthopaedic patients immobilized in plaster cast seems possible by using the AV-impulse-system which significantly increases the venous blood flow independent from patient compliance.

Adult↗
PubMedDate not supplied

[The material properties of a combined plaster-plastic cast].

The treatment of patients by a combined plaster/plastic cast often is more advantageous than the application of only one of these components. Now a compression test was made to check the attributes of the plaster, plastic and combined material. There were shown clear differences in the elastic behavior and the solidity of both casts, and the combination of both materials consequently was not really stable.

Calcium Sulfate↗
PubMed2002

Incorporation of a cast, embossed identification plate into a partial denture framework.

This article presents a technique for the fabrication and incorporation of a stable and fireproof identification plate into a cast partial denture framework. Embossing tape is embedded in the wax pattern of the major connector. The resulting casting reproduces the embossed lettering, which is identifiable through the tissue-colored acrylic denture base resin.

Dental Casting Technique↗
PubMed2001

Retinal vascular changes in rats with inherited hypercholesterolemia--corrosion cast demonstration.

PURPOSE: To demonstrate specific hypercholesterolemic changes in the retinal vascular architecture. METHODS: Corrosion casts of 12- to 18-month-old rats with inherited hypercholesterolemia (RICO) and of control Wistar Kyoto (WKy) rats were examined with a scanning electron microscope (SEM). The diameters of the retinal arteries, veins and capillaries were measured in photographs with a caliber micrometer. The capillary branches were counted in the micrographs with the use of Adobe Photoshop. The retinal capillaries were examined by transmission electron microscopy (TEM). RESULTS: SEM examination of the vascular casts of 15-month-old RICO rats showed slight tortuosity of large vessels at the posterior pole of the retina. The precapillary arterioles branching from the major artery were longer and straighter than normal. Retinal capillary changes such as caliber irregularity and narrowing in the capillary network were more severe in 18-month-old RICO rats. The most prominent finding was marked straightening of the capillaries in the inner and outer layers of the capillary network, which looked like fine strings. Intercapillary spaces became wider, and finally capillaries looked scattered. The diameter of the retinal capillaries lumen in RICO rats was significantly narrower than that in WKy rats (p < 0.0001). The capillary branches were fewer in 18-month-old RICO rats than that in 18-month-old WKy rats (p < 0.0001). Neither local stenosis or obstruction in the arterioles and venules nor any arteriovenous crossing defect was seen in young and old RICO rats. Transmission electron microscopy of 16-month-old RICO rat retinas revealed that the capillaries in the inner and outer plexiform layers contained scarce cytoplasmic components, vacuoles in endothelial cells and basement membranes of irregular thickness. Capillary pericytes were swollen and irregular in shape, contained vacuolated mitochondria and scarce cytoplasmic components. CONCLUSIONS: These findings indicate that the retinal capillary changes are probably related to hypercholesterolemia.

Animals↗
PubMed2001

Corrosion casts and scanning electron microscopy of choroidal vasculature in rats with inherited hypercholesterolemia.

PURPOSE: The purpose of the present study is to determine the specific morphological changes in choroidal vasculature due to hypercholesterolemia. METHODS: The choroidal vessels of rats with inherited hypercholesterolemia (RICO) were examined by the corrosion cast technique and electron microscopy. RESULTS: In 18-month-old RICO rats, corrosion casts and scanning electron microscopy showed severe tortuosity, caliber irregularity and generalized dilatation of the large choroidal arteries and veins. The branch arterioles and draining venules were also tortuous and dilated. The ampullae of the vortex veins were wide, but no arteriovenous anastomoses, crossing defects or obstruction were seen. However, there were many venular collateral channels and venulo-venular anastomoses. The choriocapillaries appeared normal. Transmission electron microscopy of the choroidal vessels showed hypertrophy of smooth muscle cells and irregular thickening of the basement membrane. The RPE and Bruch's membrane were intact. CONCLUSION: These findings indicate that the choroidal vascular changes are probably related to hypercholesterolemia. The results of the present study will be useful in the interpretation of the changes seen in hypertensive, diabetic and aged choroids.

Animals↗
PubMed1989

Fiberglass versus plaster casts. How to choose between them.

Both fiberglass and plaster of Paris casts have advantages and disadvantages, and the choice of material depends on the individual situation. Fiberglass is used most often, but plaster of Paris, with its molding capabilities, is the first choice for fresh extremity fractures. "Hybrid" casts offer no advantages.

Calcium Sulfate↗
PubMedDate not supplied

Pregnancy wastage in scheduled caste women of Punjab.

The present report is an attempt to secure adequate data about pregnancy wastage in scheduled caste women of Punjab who do not use any family limiting method. Analysis of reproductive histories of 922 Scheduled Caste women reveals that in the maternal age group 25-29 years, the mothers experienced the least number of abortions and still births. However, beyond this the risk of pregnancy wastage increases with age.

Abortion, Spontaneous↗
PubMed2003

Pilot study: data-capturing consistency of two trans-tibial casting concepts, using a manikin stump model: a comparison between the hands-on PTB and hands-off ICECAST compact concepts.

The quality of fit of a trans-tibial patellar tendon bearing (PTB) socket may be influenced by consistency in casting, rectification or alignment. For this study two distinctive different data-capturing concepts were tested in relation to prosthetist performance. The hands-on PTB and hands-off ICECAST compact concept were studied and compared for inter- and intra-prosthetist consistency using a specially designed manikin stump model. A purpose designed digitiser was used to scan a selected surface area of the produced models, 5 for each concept, 10 in total. The extent of casting consistency at each of 936 locations per plaster model was calculated and the level of consistency was quantified. This study has shown that by using the manikin model there is a clear indication that the investigated hands-off concept produces more consistent results than the hands-on concept.

Amputation Stumps↗