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Biomedical subjects

M Rohlin

Publications and source records attributed to M Rohlin.

At least 109 records · Page 6Linked to original sources
PubMed1985

Initial Tc-99m diphosphonate uptake in mineralized and demineralized bone implants in rats.

Radionuclide imaging has been suggested as a means to assess healing and viability of bone grafts and implants. This study deals with the in vivo uptake of 99mTc-MDP in the initial postoperative period in rats. Isogeneic or xenogeneic bone was implanted in subcutaneous pouches. The isogeneic grafts and implants were treated with saline or freeze-treated or demineralized. The xenogeneic implants consisted of Kiel bone or collagen sponge. One day after surgery, the accumulation of 99mTc after an intraperitoneal injection of 99mTc-MDP was seen in all grafts and implants containing bone mineral independent of prior treatment of the graft and implant. In implants composed of only the organic part of bone, no accumulation was observed. One prerequisite for accumulation of 99mTc-MDP is the presence of the inorganic phase. Thus, the interpretation of the initial postoperative scan is based on whether or not the graft or implant initially contained mineral.

Animals↗
PubMed1985

Temporomandibular joint sounds in patients with disc displacement.

Temporomandibular joint sounds have been viewed as signs of different pathological changes. However, the correlation between joint sounds on the one hand and function and morphology of the joint on the other, are not well documented. We have therefore presurgically recorded sound from 35 operated joints with disc displacement and have studied arthrographically and during surgery the position, function and configuration of the disc as well as arthrotic changes. 12 joints were silent, 12 elicited reciprocal clicking, 3 single clicking, and 8 crepitation. Joints with reciprocal clicking consistently showed disc displacement with reduction and silent and crepitating joints showed disc displacement without reduction. All joints with reciprocal clicking as well as most silent joints demonstrated non-arthrotic articular surfaces, whereas crepitation was recorded in both arthrotic and non-arthrotic joints. Our results implied that crepitation is a rather unreliable sign of arthrosis. Reciprocal clicking can be considered as an accurate sign of reduction of anteriorly displaced discs. However, neither the degree of displacement nor the degree of deformation of the disc could be disclosed by analysis of the sound. This information can only be obtained by further examination, such as arthrotomography.

Adolescent↗
PubMed1985

Observer performance in assessment of condylar position in temporomandibular joint radiograms.

The condylar position at centric occlusion has been considered important in diagnosis of the temporomandibular joint. The present study describes inter- and intra-observer variation in radiographic assessment of condylar position. One radiogram obtained by using an individualized lateral oblique transcranial projection and three corrected sagittal tomograms from the lateral, central, and medial parts of the joint were selected from each of 31 patients. In the resulting 124 radiograms three observers assessed the position of the condyle as posterior, central, or anterior on two occasions, 3 months apart. Concordant reports for all three observers were found in 63%. The interobserver agreement two by two ranged between 69% and 79%, whereas the intraobserver agreement ranged between 81% and 90%. The observer variation and limitations of radiographic techniques should be considered when the therapeutic implication of condylar position is discussed.

Dental Occlusion, Centric↗
PubMed1984

Apical root anatomy of impacted maxillary canines. A clinical and radiographic study.

When planning autotransplantation of impacted maxillary canines, it is advantageous to know not only the position but also the root anatomy. Radiographic and clinical findings on the root anatomy of 65 impacted maxillary canines were compared. The apices were judged as straight or deflected. The positions of the canines were also recorded. Twenty-eight canines (43%) had a straight and 37 (57%) a deflected apex. The radiographic diagnosis was confirmed in 49 canines, which means a diagnostic accuracy of 75%. The misinterpretation, consisting of seven false-positive and nine false-negative diagnoses, was due to insufficient radiographic examination (7 canines), observation errors (7 canines), and limitations of radiographic examination (2 canines). No association was found between the root anatomy and position. The results show than an optimal radiographic examination and knowledge of any apical deflection are valuable aids to operative assessment of impacted maxillary canines.

Adolescent↗
PubMed1984

Internal derangement related to osteoarthrosis in temporomandibular joint autopsy specimens.

In 127 temporomandibular joint autopsy specimens the position (superior 44%, partially anterior 22%, completely anterior 34%) and configuration of the disk (biconcave 56%, biconvex 10%, others 34%) were related to osteoarthrosis. All biconvex disks were positioned anteriorly and associated with osteoarthrosis. Biconcave disks were mostly positioned superiorly and associated with normal surfaces.

Adult↗
PubMed1984

Radiation dosimetry in radiology of the temporomandibular joint.

The absorbed doses and energy imparted during conventional radiography and tomography of the temporomandibular joint were examined. Absorbed doses from the lateral-oblique transcranial projection and lateral tomography were low (0.02 to 7 mGy). From the axial projection the thyroid gland and salivary glands received a substantial dose (15 to 54 mGy) which was considerably decreased using an improved design of collimator. Radiation to the lens of the eye for the transmaxillary projection and for frontal tomography was 3 to 8 mGy. This can be reduced by a factor of 25 using lead-glass eye shields. The mean energy imparted from a bilateral examination of the temporomandibular joints using axial projection, four exposures for the transcranial lateral-oblique views, two exposures in the transmaxillary projection and lateral tomography views using a multi-film cassette was 34 mJ. The axial projection accounted for 50% of this figure.

Eye↗
PubMed1984

Diagnostic accuracy of double-contrast arthrotomography of the temporomandibular joint: correlation with postmortem morphology.

The diagnostic accuracy of double-contrast arthrotomography in the evaluation of internal derangement of the temporomandibular joint is unknown. Therefore, findings from double-contrast arthrotomograms of 48 temporomandibular joint autopsy specimens were correlated with postmortem morphology seen from dissections or cryosections. Arthrotomographic diagnosis was confirmed in 41 joints, signifying a diagnostic accuracy of 85%. Misinterpretations were made in seven joints (three concerning the configuration, three concerning the position, and one concerning the configuration and position of the disk). False-positive reports due to observation errors can be avoided with improved knowledge of the joint anatomy as well as with increased experience in the technique. False-negative examinations were due to limitation of the tomographic reproduction of the lateral part of the joint.

Adult↗
PubMed1984

On direct currents and bone formation in demineralized bone transplants.

The effect of direct current on the remineralization of a bone defect was studied in the rabbit. Bone defects in the radius of both forelegs were grafted with demineralized autologous bone. On both sides platinum electrodes were placed around the graft, and one side was connected to a power source delivering 20 microA constant current during the experimental period of 28 days. The remineralization was evaluated 14 and 28 days after operation by scintigraphy and roentgenography, planimetry included. At 28 days after operation this evaluation was supplemented by autoradiography. Roentgenographically, there was no difference between the two sides. At 14 days after operation scintigraphy demonstrated a minor delay in bone formation at the electrostimulated side. Between 14 and 28 days a significant increase in activity was noticed. On both sides, autoradiograms showed areas without uptake around the wires. It was concluded that direct currents of the studied magnitude have a negative influence on the primary bone induction process but also that it seems to influence the mineralization positively later in the bone-forming process.

Animals↗
PubMed1984

Bilateral degenerative changes and deviation in form of temporomandibular joints. An autopsy study of elderly individuals.

The right and left temporomandibular joints were removed as blocks from the skulls of 22 individuals in the 60-89-year-old age group at autopsy. The skulls were examined to determine the number and position of teeth and dentures. The articular surfaces of the joints were examined macroscopically for topographical distribution and degree of degenerative changes and topographical distribution of deviation in form. Indices of degenerative changes and of deviation in form were proposed. Correlations were found between the right and left joints with respect to both indices for degenerative changes and deviation in form. The indices were also correlated with each other within the same joint. A sex difference was found for degenerative changes and deviation in form, with the most advanced changes in the joints of women. It was concluded that degenerative changes and deviation in form in this age group were correlated between right and left joints and within the same joint.

Aged↗
PubMed1983

Bone formation in demineralized bone transplants treated with biosynthetic human growth hormone.

The influence of local administration of biosynthetic human growth hormone on the bone formation in a rabbit bone defect grafted with demineralized autologous bone was studied and compared to contralateral saline administration. The growth hormone was produced by hybrid DNA-technique and administered locally to the bone defect with the demineralized bone implant by an osmotic pump delivering 5 microliters/h during 14 days. At 14 and 28 days after operation the bone forming process was evaluated by roentgenography, planimetry included, and scintigraphy after injection of 99Tcm-labelled DPD. At 28 days after operation also autoradiography was performed. The roentgenographic and scintigraphic examinations revealed no influence from growth hormone neither 14 nor 28 days postoperatively. Centrally in the remineralized grafts the roentgenograms 28 days after operation showed radiolucent areas which in corresponding autoradiograms showed no uptake of 99Tcm. These areas turned out to be remnants of matrix. It is suggested that growth hormone has no influence on the bone induction process during the first 14 days when administered to bone matrix, probably due to relative lack of osteogenic cells. This study contributes a base for further evaluation of factors pertinent to hormonal stimulation of bone matrix transplants.

Animals↗
PubMed1983

Osteogenetic activity in composite grafts of demineralized compact bone and marrow.

The effects of a composite graft of autologous marrow and demineralized autologous compact bone on the healing of a surgically created bone defect were observed in adult rabbits. A segment of the radius was bilaterally resected, demineralized, and replaced. On one side the bone graft was supplemented with autologous marrow. The new bone formation was measured 14 and 28 days after operation by roentgenography, including planimetry with scintigraphy and autoradiography using 99mTc-labelled MDP. The composite graft, i.e., demineralized compact bone and marrow, had a significantly higher (p less than 0.01) bone formation rate 14 days after operation compared with the graft with demineralized compact bone in the opposite radius. At 28 days, however, there were no differences between the sides. Viable autologous marrow cells and demineralized autologous compact bone graft accelerate the rate of osteogenesis, but only at the beginning of the healing process.

Animals↗
PubMed1982

Demonstration of 99mTc-labelled plasmin on the surface of ex vivo thrombi.

In an vitro system using the Chandler model for the preparation of in vitro thrombi trace amounts of porcine or human 99mTc-labelled plasmin was found to adsorb to the surface of a preformed thrombus. A radioactive lining of the thrombus could be demonstrated using autoradiography after addition of 99mTc-labelled plasmin in concentrations of 0.04 - 0.07 or 0.4 - 0.7 CTA u/thrombus made from 2 ml whole blood (0.035 - 0.35 microM). The same pattern was found for porcine as for human plasmin. The presence of tranexamic acid in concentrations of 3 to 12 mM did not affect the binding of plasmin indicating that the plasmin binding to fibrin was independent of the lysine binding sites. Furthermore alpha 2-antiplasmin was demonstrated on/in the thrombus also when no plasmin was present indicating a binding of alpha 2-antiplasmin to the thrombus. The plasmin bound to the thrombus was proteolytically inactive. In order to obtain thrombolysis most of the alpha 2-antiplasmin in the surrounding medium had to be neutralized.

Animals↗
PubMed1980

Double-contrast tomography of the temporomandibular joint. A new technique based on autopsy specimen examinations.

Double-contrast tomography was applied to temporomandibular joint autopsy specimens. Both joint compartments were given successive injections of air-iodine contrast medium-air. Tomography was performed in lateral and a.p. projections using a multi-film cassette. The shape of the disc and joint compartments was well demonstrated. The influence of the tomographic level and the position of the condyle on the appearance of the disc was analysed.

Autopsy↗
PubMed1978

In vitro interaction between 99Tcm-labeled pyrophosphate, 32P-labeled pyrophosphate and rat tissues.

Whole-body sections from young rats were incubated with solutions containing 32P-labeled pyrophosphate, 99Tcm-labeled pyrophosphate and 99Tcm-pertechnetate, respectively, at pH 7.6 or pH 8.6. After incubation, the sections were used for autoradiography and/or staining in order to visualize tissue affinity for 99 Tcm and areas of pyrophosphatase activity. At pH 7.6, the distribution patterns of 99Tcm-labeled pyrophosphate and 32P-labeled pyrophosphate were similar. When pH was raised to 8.6, 99Tcm-labeled pyrophosphate was degraded before reaching the tissues and their enzymes. The distribution pattern of 99Tcm-labeled pyrophosphate at pH 8.6 was similar to that of 99Tcm-pertechnetate. 32P-labeled pyrophosphate could serve as a substrate for alkaline pyrophosphatase and the enzyme activity was demonstrated autoradiographically.

Animals↗
PubMed1977

Quantitative analysis of the distribution of 99mTc-labelled ethylene hydroxy diphosphonate in young rats.

The distribution of 99mTc-labelled ethylene 1-hydroxy-1,1-diphosphonate (EHDP) in young rats was studied 1, 3, 6 and 9 h after intraperitoneal injection. The concentration of 99mTc in bone was 8-10 times higher than that in the kidneys and 20-1000 times higher than those in other soft tissues. The concentration in bone remained constant throughout the observation time. In some of the animals sacrificed after 3, 6, or 9 h the uptake in the liver and spleen was higher than that found in the majority of the animals.

Animals↗
PubMed1977

Distribution of 99Tcm-labelled phosphorus compounds, 45Ca and 85Sr in diphosphonate-treated rats.

A similar distribution of 99Tcm, 45Ca and 85Sr was obtained when injected in rats as 99Tcm-labelled pyrophosphate or ethylene-1-hydroxy-1,1-diphosphonate (EHDP), 45Ca-chloride and 85Sr-choloride respectively. The highest concentrations occurred in bone and teeth. In EHDP-treated rats, isotopes were accumulated at sites of ectopic calcifications in the lung, kidney and stomach wall as well as in mineralized tissues. These results indicate that 99Tcm, when administered as 99Tcm-labelled EHDP accumulates predominatly in the inorganic rather than organic tissue components.

Animals↗