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PubMed1985

A re-examination of otoconia from the Shaker mouse.

We have studied saccular and utricular otoconia from Shaker-1 and Shaker-2 mice by X-ray diffraction and scanning electron microscopy. In contrast to previous reports, we found that the crystals were composed of calcite rather than polycrystalline hydroxylapatite. These crystals were indistinguishable mineralogically and morphologically from normal mouse otoconia. The reported occurrence of hydroxylapatite otoconia in the Shaker mouse is probably false.

Animals↗
PubMedDate not supplied

The misuse of the Lapidus procedure: re-evaluation of the preoperative criteria.

Fusion of the metatarsocuneiform joint has been documented in the literature for a number of conditions affecting the first ray. The fixation techniques have advanced greatly since Lapidus advocated the procedure, but the indications need to remain rigid and narrow. The review of the literature illustrates numerous complications, and this case presentation specifically depicts the long convalescence of the failed fusion of the first metatarsocuneiform joint. The Lapidus procedure ultimately should be used as a last resort to eliminate painful arthrosis from the metatarsocuneiform joint, reduce severe deformity, or give medial column stability to a paralytic or a spastic foot. If no pathology exists within the metatarsocuneiform joint, then surgeons should use other procedures to correct pathology of the first ray in elective foot surgery.

Adult↗
PubMed2005

A 3D analysis of mechanically stressed dentin-adhesive-composite interfaces using X-ray micro-CT.

Dentin bonding systems (DBS) have been developed in order to bond restorative materials (i.e. composite) to tooth tissues when function and integrity have to be re-established. Adhesion to dentin results from the penetration of DBS into the demineralised substrate constituted by a conditioned collagen network. The long-term stability of a restored tooth is mainly affected by the seal of the restorative material on the dental structures. Although leakage through the dentin-DBS interface has been widely reported, 3D investigation technique and accurate non-destructive measurements of leakage as functions of mechanical cycling have never been provided. To address these issues, the properties of the material interface are analysed using micro-tensile static and dynamic tests, assisted by the finite element modelling and by the X-ray computed micro-tomography. The dual energy absorption technique, with the synchrotron beam light, has been developed to investigate, in a non-destructive manner, the effect of mechanical cycling on leakage of a silver nitrate staining solution at the dentin-DBS interface. The effect of the pulpal roof on the stress distribution in the coronal dentin-DBS-composite interface has been investigated and the level at which the state of stress can be assumed to be uniform within acceptable limits has been defined. The tensile static and dynamic results suggest that the adhesive strength for the multi-step DBS resulted significantly higher than the other investigated DBS. Imaging results indicate that 3D leakage occurs radially at the dentin-adhesive interface through the interface itself rather than through the unconditioned dentin bulk; moreover, the dynamic tensile loading allows a more diffuse staining penetration.

Absorptiometry, Photon↗
PubMed1996

Alterations in the progression of cells through the cell cycle after exposure to alpha particles or gamma rays.

A G1-phase delay after exposure to alpha particles has not been report ed previously, perhaps because immortalized cell lines or cell lines from tumor cells were used in past studies. Therefore, we compared the effects of alpha particles (0.19 or 0.57 Gy) and approximately equitoxic doses of gamma rays (2 or 4 Gy) on progression of cells through the cell cycle in normal human skin fibroblasts. Cell cycle analyses were performed using flow cytometry by measuring incorporation of bromodeoxyuridine (BrdUrd) in each phase of the cell cycle up to 44 h after irradiation. We observed an alpha-particle-induced G1-phase delay in human skin fibroblasts even at the lowest dose, 0.19 Gy. At equitoxic doses, more pronounced and persistent G1-phase delays and arrests were observed in gamma-irradiated cultures in that increased fractions of the G1-phase cells remained BrdUrd- over the course of the study after gamma-ray exposure compared to cells exposed to alpha particles. In addition, G1-phase cells that became BrdUrd+ after gamma irradiation re-arrested in G1 phase, whereas BrdUrd+ G1-phase cells in alpha-particle-irradiated cultures continued cycling. In contrast, comparable percentages of cells were delayed in G2 phase after either alpha-particle or gamma irradiation. Both gamma and alpha-particle irradiation caused increases in cellular p53 and p2lCip1 shortly after the exposures, which suggests that the G1-phase delay that occurs in response to alpha-particle irradiation is dependent on p53 like the initial G1-phase delay induced by gamma rays.

Alpha Particles↗
PubMed1999

Merits of soft nitriding scalers.

BACKGROUND: It has been demonstrated that nitriding modifies the physical characteristics of metals. The purpose of this study was to evaluate the changes induced by 3 levels of inexpensive soft nitriding treatments on commercial sickle scalers. METHODS: Taglite scalers (NT) were soft nitrided for 30 (SN30), 60 (SN60), or 90 (SN90) minutes. The cumulated scaled material was weighed every 10 strokes x 10 and thereafter every 1,000 to 8,000 strokes by an automatic scaling apparatus against epoxy resin. Weight differences were used to indicate abrasion resistance; the relative efficiency (RE) was calculated as the ratio of scaled amount at a given number of strokes (SN/NT). The hardness and the tensile strengths were determined for each soft nitriding treatment level. The nitrided layer thickness of representative SN scalers was observed by electron probe x-ray microanalysis. RESULTS: The SN60 was not significantly different from SN30 or SN90, but the SN90 was more efficient than SN30 for the first 100 strokes (P<0.01). The RE of all SN scalers was significantly greater (2.3 to 2.7 times) than the NT scalers from the beginning of the study and throughout all time periods (SN90 > SN60 > SN30); it increased further during the first 100 strokes (9.7 to 15.5 times), indicating the NT scalers wore out faster than SN scalers. The untreated scalers' performance decreased to 10% of baseline after 100 strokes; but even after 1,000 strokes, the SN60 and SN90 performed better than new untreated scalers. Thereafter, all scalers' performance, including SN scalers, decreased. While the NT blades ceased to cut measurable amounts after 7,000 to 8,000 strokes, all SN scalers continued to cut. Although SN90 scalers had the thickest soft layer and were the hardest (P<0.01), the SN60 had the highest tensile strength (P <0.01), suggesting that it might be the safest in practice. CONCLUSIONS: Sixty minutes of soft nitriding treatment of commercially available taglite scalers seem to be the optimal treatment duration to increase their durability, on the order of 100 to 1,000 times, without jeopardizing safety for clinical use.

Dental Alloys↗
PubMed2004

The structural dynamics of myoglobin.

Conformational fluctuations in proteins were initially invoked to explain the observation that diffusion of small ligands through the matrix is a global phenomenon. Small globular proteins contain internal cavities that play a role not only in matrix dynamics but also in controlling function, tracing a pathway for the diffusion of the ligand to and from the active site. This is the main point addressed in this Review, which presents pertinent information obtained on myoglobin (Mb). Mb, a simple globular heme protein which binds reversibly oxygen and other ligands. The bond between the heme Fe(II) and gaseous ligands can be photodissociated by a laser pulse, generating a non-equilibrium population of protein structures that relaxes on a picosecond to millisecond time range. This process is associated with migration of the ligand to internal cavities of the protein, which are known to bind xenon. Some of the results obtained by laser photolysis, molecular dynamics simulations, and X-ray diffraction of intermediate states of wild-type and mutant myoglobins are summarized. The extended relaxation of the globin moiety directly observed by Laue crystallography reflects re-equilibration among conformational substates known to play an essential role in controlling protein function.

Amino Acid Sequence↗
PubMed1997

Cranioplasty with autogenous autoclaved calvarial bone flap in the cases of tumoural invasion.

When a bone flap is raised in the course of a craniotomy, the ideal is to replace it at the end of the procedure. When it is invaded by tumoural cells, it cannot be replaced due to the risk of tumoural recurrence. In these cases we have autoclaved the bone flap to be able to replace it with no fear of tumoural recurrence. Between October 1989 and October 1995 sixty-two patients required autoclaving of the bone flap in the course of a craniotomy due to tumoural invasion (thirty-five meningiomas, sixteen bone tumours, five metastases, and eight scalp tumours). The infiltrated bone flaps were removed, cleaned, autoclaved for 20 minutes at 134 degrees C and 1 kg/cm2 and re-implanted. Patients were followed-up for 10 to 58 months (average 41 months). At every follow-up visit skull x-ray studies, clinical examination, and photographs were done. When needed a CT scan was performed to assess the thickness of the bone flap. On follow-up roentgenograms partial resorption was observed in twelve cases (19.3%). CT scan studies showed loss of thickness in another thirty-five cases (56.4%). Meanwhile the external aspect remained unchanged. In six cases (3.2%) biopsies of the bone flaps were taken at a second surgical procedure. They showed newly formed bone partly re-populated by osteocytes but retaining areas of sequestered bone. We conclude that autoclaved bone, if replaced with direct contact with living bone, it is gradually repopulated with osteocytes. Cranial vault autoclaved autologous bone flap is a good alternative when the original bone flap is invaded but not destroyed by tumoural cells.

Bone Transplantation↗
PubMed2005

Picolylamine-methylphosphonic acid esters as tridentate ligands for the labeling of alcohols with the fac-[M(CO)3]+ core (M = 99mTc, Re): synthesis and biodistribution of model compounds and of a 99mTc-labeled cobinamide.

[(Methyl-pyridin-2-ylmethyl-amino)-methyl]-phosphonic acid is a new bifunctional chelator for the fac-[(99m)Tc(CO(3))](+) core which can be linked to biomolecules via formation of phosphonic acid esters. Its synthesis and the coupling to model alcohols and to a bioactive molecule (cobinamide) are described. The rhenium complexes [Re(CO)(3)L] of the esters have been prepared and characterized, one of them by X-ray crystallography. The model esters could be labeled with [(99m)Tc(OH(2))(3)(CO)(3)](+) under mild conditions and relatively low ligand concentration with >97% yield and only one isomer formed. The (99m)Tc-labeled cobinamide analog was a mixture of four isomers. It bound strongly to transcobalamin I (TC I, haptocorrin) but only slightly to transcobalamin II (TC II) and intrinsic factor (IF), reflecting the binding abilities of cobinamide. Biodistribution studies in mice with B(16) melanoma exhibited fast clearance with no specific tissue binding.

Alcohols↗
PubMedDate not supplied

[Sudden deafness and biometric function analysis of the cervical spine].

Theories concerning the influence of function disturbances of the cervical spine on the development of sudden hearing loss should be re-examined. Forty-eight patients with unilateral sudden hearing loss and 94 controls were examined. X-rays of the cervical spine were made in lateral projection in normal position, and in maximum flexion and extension. The posture and movement of the vertebrae were recorded using a computer digitalization program. Overall mobility of the cervical spine was reduced in the group with sudden hearing loss: reduced movement was found in segments C2/C3, C5/C6, and C6/C7. Segments P0/P1 and C1/C2 were conspicuous by very high standard deviations in the group with sudden hearing loss. The results indicate that sudden hearing loss and function disorders of the cervical spine are related.

Biomechanical Phenomena↗
PubMed1984

Influence of the method of re-expansion of atelectatic lung upon the development of pulmonary edema in dogs.

An endobronchial tube was used to separately ventilate each lung in anesthetized dogs, and absorption atelectasis was then induced in the left lung and maintained for 3 1/2 h. The left lung was partially re-expanded by ventilation at normal tidal volumes for 10 min, and then completely re-expanded by manual hyperinflation. This delayed re-expansion was associated with an extravascular water content significantly greater than that of the right lung. A previous study demonstrated no increase in the ratio of left to right lung water content after 3 h of atelectasis alone and a significant increase after immediate hyperinflation. Delayed re-expansion produces significantly different results, and it is therefore concluded that the method of lung re-expansion influences the development of pulmonary edema after atelectasis.

Animals↗
PubMed2003

Peritoneal implantation of ureter in a cadaveric kidney transplant recipient.

We report here a case of a kidney transplant recipient in whom the ureter was initially implanted into the peritoneum. Excessive ultrafiltration volume and reversal of serum vs dialysate creatinine ratio when the patient was recommenced on continuous ambulatory peritoneal dialysis first suggested the diagnosis which was subsequently confirmed by a plain abdominal x-ray demonstrating placement of ureteric stent in the peritoneum. This rare complication was successfully corrected with surgical re-implantation of ureter into the bladder and 5 years later, the patient remains well with good graft function.

Adult↗
PubMed1992

Acute hemarthrosis of the knee.

Rapid swelling of the knee following a blow or twisting injury is considered a significant injury. The history of trauma coupled with a thorough examination should provide an accurate diagnosis in most patients. Although it should not be performed routinely, aspiration of the fluid can be done to aid in making a diagnosis and to alleviate pain. Splinting and re-evaluation are recommended as the initial treatment of an acute hemarthrosis. Ancillary testing that includes x-ray films and MRIs is beneficial. Although arthroscopic evaluation of the knee is not needed in every patient with an acute hemarthrosis, a high percentage of these patients eventually undergo arthroscopy to complete the diagnosis or as a means of early surgical intervention. The decision to surgically repair an injured structure depends on the patient's age, activity level, amount of instability, and associated lesions. Routine arthroscopy is indicated as a means to determine the correct treatment and not merely for diagnosis. With knowledge of the common causes of hemarthrosis and understanding of the knee examination, a trained examiner can make an accurate diagnosis 80% to 90% of the time and prescribe the appropriate treatment.

Acute Disease↗