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PubMed1996

[Spongiosa structure and polyostotic heterogeneity in osteoporosis. Mechanism of bone transformation, morphology, clinical significance].

Osteoporosis is the most frequent generalized bone disease. The clinical expression of postmenopausal osteoporosis is characterized by spontaneous fractures of the vertebral bodies which affect mainly the trabecular bone structure. Thus the morphological bone transformation in osteoporosis is of clinical relevance. The object of this study was to analyze quantitatively and qualitatively the distribution of three-dimensional structure of cancellous bone in the human spine in osteoporosis. Therefore the complete anterior column of the spine and bone biopsies of the iliac crest of 11 autopsy cases with proven osteoporosis and 26 autopsy cases without primary or secondary bone disease were removed. A 1-mm-thick prepared sagittal section through the center of all vertebral bodies was embedded undecalcified in plastic and stained on the surface using a modification of the von Kossa method. This technique allowed combined two- and three-dimensional measurements simultaneously; these included evaluation of trabecular bone volume, trabecular interconnection, trabecular thickness, and trabecular number. The quantitative spine deformity index and qualitative analysis of the trabecular bone structure completed the investigation. The bone loss in osteoporosis is a loss of structure and the loss of whole trabeculae caused by perforations. The age-related decrease of trabecular bone mass is due to the transformation from plates to rods. Patient with osteoporosis show pathologically diminished trabecular bone volume and apparently reduced trabecular interconnection, while trabecular thickness and trabecular number show age-dependent change. The polyostotic heterogeneity in osteoporosis is immense. Neighboring vertebral bodies show differences of up to 100% in bone volume and bone structure. Due to this fact it is impossible to define a threshold for osteoporotic fractures. At the moment the transformation and loss of trabecular bone structure in osteoporosis is assumed to be irreversible; therefore, early prophylaxis is necessary to prevent clinical manifestations of these changes of bone.

Adolescent↗
PubMed1983

Ultrastructural study of motor endings on long chain intrafusal fibers in muscle spindles of the cat.

Five complete poles of long nuclear chain intrafusal fibers of cat tenuissimus muscle spindles embedded in a plastic medium were cut in serial, 1 micron thick transverse sections and stained with toluidine blue. Each fiber pole displayed one plate-type motor ending positioned outside the encapsulated part of the spindle. Ultrastructurally, the endings resembled extrafusal end-plates and were more complex, in terms of prominence of sole-plate and degree of post-junctional folding, than any other motor ending present in the spindles. They were identified as the terminals of static (fast) skeletofusimotor axons, which preferentially innervate the longest nuclear chain fibers of cat spindles.

Animals↗
PubMed1986

Effects of subchronic inhalation of low concentrations of nitrogen dioxide. I. The proximal alveolar region of juvenile and adult rats.

Inhalation of nitrogen dioxide (NO2) produces injury to the epithelium of terminal airways and the alveoli proximal to the airways. Techniques were devised to isolate alveolar tissue from this region for morphometric studies to define the extent of alveolar septal injury caused by NO2. One-day-old and six-week-old rats were exposed to either room air or 0.5 ppm NO2 for 23 hr per day 7 days per week for 6 weeks. An additional group of 6-week-old rats were exposed to 2.0 ppm NO2 for the same duration. Two daily hour spikes to three times the background concentrations (0.5 to 1.5 ppm and 2.0 to 6.0 ppm) were applied Monday through Friday. At the end of the exposure, rat lungs were fixed by intratracheally infusing buffered 2% glutaraldehyde. Pieces of lung tissue were embedded in large plastic blocks which were softened with heat and thin (0.3 mm) sliced. Terminal bronchioles and their corresponding proximal alveolar regions were identified from the thin plastic slices, removed, and glued to cylindrical EM blocks for thin sectioning. Morphometric analysis revealed that epithelial injury occurred in all exposed animals. The juvenile rats which had been exposed to 0.5 ppm NO2 since 1 day of age exhibited changes in the characteristics of type II epithelial cells. These cells spread to cover more alveolar surface and became thinner. Adult animals exposed to 0.5 and 2.0 ppm NO2 showed changes in alveolar macrophages and in the alveolar interstitium in addition to changes in the epithelium. Animals exposed to 0.5 ppm NO2 showed spreading and hypertrophy of type II epithelial cells. Those animals exposed to the higher concentration of NO2 had similar changes in type II epithelial cells and in addition showed an increase in type I cell number. The type I epithelial cells were smaller and covered less alveolar surface area than normal type I cells, suggesting a regenerating population of type I cells. These results suggest that prolonged exposure to low concentrations of NO2 can cause injury to the alveolar epithelium indicated initially by spreading and hypertrophy of type II cells followed by differentiation into type I cells to compensate and repair the injury. Adult rats were as sensitive or more sensitive to NO2 injury than were juvenile rats.

Aging↗
PubMed1989

A port film marker.

A device is described consisting of brass strips embedded in a plastic plate. When inserted in a radiation beam, it produces an image of a cross centered in the field. Cuts in the brass at defined intervals project a scale on the film used to determine a magnification factor. A marker in the lower right-hand quadrant provides rapid, unequivocal orientation of the film. This capability of orientation to a beam's-eye-view makes anatomical markers redundant.

Equipment Design↗
PubMed2006

Conformational effects of Gly-X-Gly interruptions in the collagen triple helix.

The collagen model peptide with sequence (Pro-Hyp-Gly)4-Pro-Gly-(Pro-Hyp-Gly)5 contains a central Gly-Pro-Gly interruption in the consensus collagen sequence. Its high-resolution crystal structure defines the molecular consequences of such an interruption for the collagen triple-helical conformation, and provides insight into possible structural and biological roles of similar interruptions in the -Gly-X-Y- repeating pattern found in non-fibrillar collagens. The peptide (denoted as the Hyp minus peptide or Hyp-) forms a rod-like triple helix structure without any bend or kink, and crystallizes in a quasi-hexagonal lattice. The two Pro-Hyp-Gly zones adopt the typical triple-helical collagen conformation with standard Rich and Crick II hydrogen bonding topology. Notably, the central zone containing the Gly-Pro-Gly interruption deviates from the standard structure in terms of hydrogen bonding topology, torsion angles, helical, and superhelical parameters. These deviations are highly localized, such that the standard features are regained within one to two residues on either side. Conformational variations and high temperature factors seen for the six chains of the asymmetric unit in the zone around the interruption point to the presence of a local region of considerable plasticity and flexibility embedded within two highly rigid and ordered standard triple-helical segments. The structure suggests a role for Gly-X-Gly interruptions as defining regions of flexibility and molecular recognition in the otherwise relatively uniform repeating collagen conformation.

Amino Acid Sequence↗
PubMed1993

Megakaryocyte markers in myeloproliferative disorders.

Identification of megakaryocyte precursors with immunohistochemical methods in bone marrow trephine biopsy specimens (embedded in a plastic resin, Immuno-Bed) was performed from patients with blastic phase of chronic granulocytic leukaemia (five cases), from chronic megakaryocytic-granulocytic myelosis (four cases) and from acute megakaryoblastic leukaemia (11 cases). In megakaryoblasts of bone marrow biopsies immunohistochemical reactions using the ABC method and monoclonal antibodies against von Willebrand antigen and GpIIb/IIIa (CD41) were visible in various percentages depending on the maturation's degree of megakaryocyte precursors. The number of circulating blast cells determined by flow cytophotometry was nearly similar to those of observed in biopsies. The greatest bone marrow reticulin content could be detected in acute megakaryoblastic leukaemia cases. Despite the different clinicopathological entities, the presence of the same phenotype (megakaryoblasts) was associated with a short survival in these haematological malignancies (in CGL MKB phase 4.0, in CMGM MKB phase 4.2, and in AML M7 5.8 months, respectively).

Adult↗
PubMedDate not supplied

The Byl-Cheney-Boczai Sensory Discriminator: reliability, validity, and responsiveness for testing stereognosis.

This study evaluated reliability, validity, and responsiveness of a new test of stereognosis (Byl-Cheney-Boczai Sensory Discriminator Test [BCBI]). Participants included 38 controls, 29 subjects with hand problems, and 3 raters. With eyes closed, after sweeping the digit over a design (10 mm x 10 mm) embedded in a plastic cube (13 mm x 13 mm), subjects matched the design palpated with a design on an answer sheet (10 trials/digits 2 and 4). The intra-class correlation coefficients were 0.997 and 0.994 for intra-rater and inter-rater reliability. No significant performance differences were found by gender or side. Accuracy was significantly higher for digit 2 versus digit 4, younger subjects versus older subjects, and controls versus subjects with pathology. There were significant (1) positive correlations (+0.41 to +0.53) between the BCBI and tests of stereognosis and graphesthesia; (2) negative correlations (-0.44 to -0.51) between the BCBI and the Purdue and digital reaction time; and (3) gains on the BCBI and function with therapy. The BCBI seems to be a reliable, valid, and responsive test of stereognosis that can be administered in 15 minutes in the cinic.

Adolescent↗
PubMed2002

A label-free optical technique for detecting small molecule interactions.

A novel approach for the label-free detection of molecular interactions is presented in which a colorimetric resonant grating is used as a surface binding platform. The grating, when illuminated with white light, is designed to reflect only a single wavelength. When molecules are attached to the surface, the reflected wavelength (color) is shifted due to the change of the optical path of light that is coupled into the grating. By linking receptor molecules to the grating surface, complementary binding molecules can be detected without the use of any kind of fluorescent probe or radioactive label. The detection technique is capable of detecting the addition and removal of small molecules as they interact with receptor molecules on the sensor surface or enzymes in the solution surrounding the sensor. Two assays are presented to exemplify the detection of small molecule interactions with the biosensor. First, an avidin receptor layer is used to detect 244 Da biotin binding. Second, a protease assay is performed in which a 136 Da p-nitroanilide (pNA) moeity is cleaved from an immobilized substrate. Because the sensor structure can be embedded in the plastic surfaces of microtiter plates or the glass surfaces of microarray slides, it is expected that this technology will be most useful in applications where large numbers of biomolecular interactions are measured in parallel, particularly when molecular labels will alter or inhibit the functionality of the molecules under study. Screening of pharmaceutical compound libraries with protein targets, and microarray screening of protein-protein interactions for proteomics are examples of applications that require the sensitivity and throughput afforded by this approach.

Avidin↗
PubMed1987

The effect of Otosporin and Gentisone HC on the mitotic index and thickness of the tympanic membrane and meatal skin in the guinea pig.

Otosporin and Gentisone HC ear drops were inserted twice daily for 3 weeks into the external auditory meatuses of guinea pigs. An intraperitoneal injection of vincristine (1 mg/kg.) was given to each animal three hours before it was killed. Temporal bones and attached external auditory meatuses were dissected, tissues were fixed in 10 per cent buffered formalin, decalcified in EDTA, and embedded in JB4 plastic for sectioning at 4 micron. The proliferative activity in the epidermis of the bony meatus and in the lateral surface of the tympanic membrane was obtained by deriving the mitotic indices. After both types of ear drops there was a statistically significant reduction in mitotic indices, the values being about half the control values. The proliferative activity in the tympanic membrane was too low to permit statistical analysis, but no differences were apparent between the groups. The thicknesses of the epidermis and dermis of the bony canal, and of the tympanic membrane, were measured using a Kontron MOP-AMO3 analyser. Although the dermis was thinner as a result of the administration of ear drops, both the epidermis of the bony meatus and that of the tympanic membrane were thicker, all these changes being statistically significant.

Animals↗
PubMed2002

Comparative evaluation of casting retention using the ITI solid abutment with six cements.

OBJECTIVE: The purpose of this study was to test the retention of metal copings fabricated to fit on the one-groove, one flat-sided solid titanium abutment using six different cements. MATERIALS AND METHODS: Ten hollow screw 3.8 mm ITI implants were mounted in acrylic resin blocks. A solid titanium abutment was placed on each implant and torqued at 35 Ncm. Prefabricated burn-out caps were placed on the titanium abutment and wax loops added to the occlusal surface to allow for subsequent retention testing. All plastic caps were embedded in phosphate-bonded investment and cast with noble alloy. Castings were inspected for surface irregularities using a stereomicroscope at 10x magnification. The six cements were: 1) eugenol-free zinc oxide (Temp Bond NE); 2) zinc-oxide eugenol (IRM); 3) zinc phosphate (Hy-Bond); 4) resin-modified glass ionomer (Protec Cem); 5) zinc polycarboxylate (Durelon) and 6) 10-methacryloyloxydecyl dihydrogen phosphate resin (Panavia 21). After cementation, implant-abutment-casting assemblies were stored for 24 h in 100% humidity. Samples were subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 0.5 mm/min. The load required to de-cement each coping was recorded and mean values for each group calculated. Means and standard deviations of loads at failure were analyzed using ANOVA and a Tukey studentized test. Statistical significance was set at P < or = 0.05. RESULTS: The mean values (+/- SD) of loads in kilograms at failure (n = 10) for the various cements were as follows: Temp Bond 3.18 (+/- 1.1) (Tukey group D), IRM 9.25 (+/- 3.83) (Tukey group CD), HY-Bond 10.9 (+/- 6.52) (Tukey group C), Protec Cem 18.98 (+/- 6.23) (Tukey group B), Durelon 23.55 (+/- 4.29) (Tukey group B) and Panavia 21, 36.53 (+/- 8.1) (Tukey group A). Means with the same letter in the Tukey grouping are not significantly different. CONCLUSIONS: The retention values of castings cemented to ITI solid abutments have not been reported in the literature. Within the limitations of this in vitro study, the results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements in their ability to retain the castings. This ranking is somehow different than that obtained when the same cements are used on natural teeth. The material and surface characteristics of the implant abutment are likely responsible for this difference. Cement retention values obtained from studies that use teeth as abutments may be misleading when used in cement-retained implant-supported crowns. It is at the clinician's discretion to use a certain type of cement, based on the situation at hand.

Analysis of Variance↗
PubMed1998

Preparation of the apical part of the root canal by the Lightspeed and step-back techniques.

This study measured in vitro the displacement of natural canal centres in 18 human teeth before and after shaping by the step-back or Lightspeed techniques. Experimental roots (n = 9 per group), embedded in clear plastic, were cross-sectioned using a 0.1-mm-thick band saw at distances 1.25 mm, 3.25 mm and 5.25 mm from the apices. A stereo microscope was used to take 35 mm slides of the cut surfaces of the sectioned roots and canals. The slides of the uninstrumented canals were scanned into a computer and saved. Each sectioned root was then reassembled and the canals shaped by the step-back or Lightspeed technique. File size 40 and instrument size 50 were selected as the master apical file and master apical rotary for the step-back and Lightspeed groups, respectively. The 18 prepared canals were photographed, and the 35 mm slides scanned and computer stored as previously. This allowed the positions of the pre- and postinstrumented roots to be electronically superimposed for subsequent analyses. Displacements of the root canal centres before and after preparation were assessed in relation to the cross-sectional diameter of the files or instruments used. In addition, increases in cross-sectional area of the root canals after preparation were evaluated in relation to the cross-sectional area of the files or instruments used. Engine-driven nickel-titanium Lightspeed instruments caused significantly less (P < 0.001) displacement of the canal centres, so roots in the Lightspeed group remained better centred than those in the step-back group. The mean cross-sectional area after preparation in the Lightspeed group was significantly less (P < 0.001) than that recorded in the step-back group. Clinically, this implies less apical transportation and less dentine destruction with the Lightspeed technique than with the step-back technique.

Dental Instruments↗
PubMed2000

Measurement of bone metal contact (BMC) in retrieved maxillofacial osseointegrated implants.

Eighteen screw-shaped extraoral osseointegrated implants retrieved from 10 patients were analysed by microradiography. Retrieved implants were trephined with a border of surrounding bone, fixed, embedded in epon plastic, ground and processed for microradiography. The reasons for retrieval were unexplained pain (n = 4), inability to cope with the implants (n = 2), fracture of central screw (n = 2), skin penetration problems (n = 1) and trauma (n = 1). The study group comprised six males and four females with a mean age of 53.4 years (range: 9-81 years). All implants were clinically stable at the time of removal, and mean osseointegration time was 3 years (range: 1-5 years). Six implants were removed from the temporal bone, five from the frontal bone and seven from the maxilla. Bone metal contact was estimated to vary between 27% and 83%. Bone metal contact was lower in the frontal bone compared to the temporal bone or maxilla, and was further reduced after preoperative irradiation. Longer osseointegration time increased bone metal contact, as did increased age up to 60 years. It is concluded that extraoral osseointegrated implants in humans may integrate morphologically as well as clinically. By microradiography it was possible to define bone metal contact in the region of implant installation.

Adolescent↗
PubMedDate not supplied

Pulmonary and neurobehavioral effects of formaldehyde exposure.

Two groups of male workers who were exposed to formaldehyde, the first group in phenol-formaldehyde-plastic foam matrix embedding of fiberglass (batt making), and the second in the fixation of tissues for histology, were studied for work-related neuro-behavioral, respiratory, and dermatological symptoms; and for pulmonary functional impairment. Forty-five male fiberglass batt makers who were studied across the initial work-shift after a holiday had average frequencies of combined neurobehavioral, respiratory, and dermatological symptoms of 17.3 for the hot areas and 14.7 for the cold areas of the process. Their symptom counts were significantly greater than those for 18 male histology technicians who averaged 7.3, and for 26 unexposed male hospital workers who averaged 4.8. During their first workshift after holidays, 58% of the batt makers had a decrease in one or more tests of pulmonary function. Nine nonsmokers had decreases more frequently than did 35 smokers; forced expiratory volume in one second FEV1.0 decreased in 16%, diffusing capacity for carbon monoxide (sb) decreased in 30%, forced expiratory flow 25-75 decreased in 16%, and forced expiratory flow) 75-85 decreased in 36%. Thirty-five percent of all 44 men had drops in FEV1.0, forced vital capacity, or in diffusing capacity (sb).

Adult↗
PubMed2007

Extremity dosimetry for radiation workers handling unsealed radionuclides in nuclear medicine departments in India.

In India, for the past five decades, whole body radiation dose of radiation workers has been monitored by means of film and thermoluminescent dosimeter (TLD) badges worn on the body. However, there are no provision/regulatory requirements to monitor doses received at the extremities, i.e., to fingers. Finger dose monitoring is essential for controlling the extremity dose limits for occupational personnel handling unsealed radioactive sources. In order to estimate the doses received in various types of procedures using unsealed sources, finger dose monitoring was carried out in 54 major institutions in the country using a specially designed plastic finger ring embedded with a TLD. The maximum finger dose of occupational workers involved in handling Tc in such activities as extraction and radiopharmacy work is 0.35 mSv GBq; during injection of radiopharmaceuticals and scintigraphy, the doses were observed to be 1 and 0.95 mSv GBq, respectively. Similarly, while handling F-FDG, the maximum doses received during dispensing, injection, and scintigraphy were 0.098, 0.324, and 0.56 mSv GBq, respectively. The maximum radiation dose received during Re/Re balloon angioplasty and while handling Sm was 3.92 and 6.5 mSv GBq, respectively. All the doses recorded were well within the prescribed limit. However, monitoring of these doses periodically would help in compiling the feedback regarding the work practices followed in institutions handling radioisotopes in the country and would also help in maintaining a record of safe work procedures while handling radioisotopes.

Equipment Design↗
PubMed1992

A method for experimental dental radiography.

An apparatus was designed for experimental dental radiography, which permitted separate adjustment of the subject, target and film. The precision of the apparatus was tested by radiographing a test subject, consisting of small steel globes embedded in a plastic plate. The subject was placed in the apparatus and exposed 30 times on dental X-ray film with different adjustments of angles and distances. All exposures were repeated after readjustment of the same form. Three linear distances between pairs of the projected steel globes were selected and measured on each radiograph. Depending on the different orientations of film, target and subject, the distances measured ranged from 9.0-11.1 mm, from 7.0-10.7 mm and from 12.7-17.3 mm, respectively. From the measurements on the radiographs the error of method was calculated to be 0.07-0.08 mm and the error of measurement to be 0.05-0.06 mm. The precision of the apparatus was thus found to be adequate for measurement of differences in small, but clinically relevant, distances.

Dental Pulp Cavity↗
PubMed2004

A Christmas tree in the larynx.

A 2 year-old boy presented with acute upper airway obstruction following a 15-month history of noisy breathing and hoarseness. An urgent laryngotracheal bronchoscopy was performed following inhalational induction of anesthesia. Using a fiberoptic bronchoscope, visualization of the larynx through a laryngeal mask airway revealed a flat plastic Christmas tree embedded within granulomatous cords causing almost complete obstruction and requiring tracheostomy prior to extraction. Twelve days later, the tracheostomy was successfully decannulated with the child's voice beginning to normalize. The family remembered the decoration from Christmas celebrations 2 years prior and recalled a coughing episode that predated the onset of hoarseness.

Airway Obstruction↗
PubMed1993

The potential for bonding titanium restorations.

PURPOSE: The use of titanium for implants has shown the biological acceptance of the metal. Recently, methods of using titanium for restorations, crowns, and bridges have been introduced using both cast and spark erosion systems for fabrication. A potential also exists for using titanium for bonded (Maryland) bridges. MATERIALS AND METHODS: In this study, the potential for bonding titanium was investigated by cementing with various adhesives: (A) metal to metal, (B) metal to enamel, and (C) comparing with a known procedure of bonding nickel-chromium. Truncated cones of pure titanium were fabricated with a 5-mm circular face for bonding to a larger titanium disc embedded in a plastic ring. A special jig was used to pull the bonded cone from the disc on an Instron tensile testing machine (Instron Corporation, Canton, MA). The resin-metal adhesives used were: (1) Infinity, (2) Metabond, (3) All-Bond 2, and (4) Panavia. These were compared with (5) nickel-chromium cones sandblasted and bonded to nickel-chromium with Panavia. Titanium cones were also bonded to human enamel with (6) Panavia and (7) Metabond. The 10 samples in each group were subjected to tensile force, and point of fracture was recorded. The data were subjected to an analysis of variance with a Scheffe F test at the 95% level of significance. RESULTS: The results of tensile forces in MPa were (1) Infinity, 28.1 +/- 3.6; (2) Metabond, 28.1 +/- 1; (3) All-Bond 2, 49.5 +/- 4.3; (4) Panavia, 57.9 +/- 3.1; (5) Panavia to nickel-chromium, 42.9 +/- 6.6; (6) Panavia to enamel, 18.5 +/- 4.7; and (7) Metabond to enamel, 19.3 +/- 3.5. Titanium was most effectively bonded with All-Bond 2 and Panavia, with Panavia samples significantly better than Panavia to nickel-chromium samples. CONCLUSIONS: It was concluded that titanium bonded restorations with certain adhesive cements were a definite possibility.

Analysis of Variance↗
PubMed1990

Encapsulated radiophosphorescent standards for day-to-day photometer calibration.

Solid, unquenched, radiophosphorescent standards for use in the day-to-day calibration of bottom viewing photometers (luminometers) were prepared by encapsulating commercially-available phosphor powders that are excited to phosphoresce by the beta- decay of 63Ni (t0.5 = 96 yr) or 14C (t0.5 = 5730 yr). The radionuclides are physically adsorbed on the phosphors by precipitation either as a "basic nickel carbonate" or as barium carbonate. The radioactive phosphors are then deposited by centrifugation as a thin layer at the bottom of the vials or tubes that are normally used in the photometer. The phosphor layer is infiltrated with a plastic resin and embedded. A light absorbing layer is subsequently cast over the phosphor layer to prevent stray light excitation of phosphorescence. The encapsulated photometer standards have remained mechanically and photometrically stable since their fabrication, which in some cases is 3 years ago. An equivalent level of visible luminescence emitted from the standards of up to 2.3 x 10(10) photons.s-1 was achieved by using an appropriate amount of radioactivity and the proper phosphor. The phosphor used in the standards could be chosen such that the radiophosphorescence emission spectrum corresponded approximately to the chemiluminescence or bioluminescence spectrum under investigation.

Calibration↗