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Biomedical subjects

R T Müller

Publications and source records attributed to R T Müller.

At least 19 recordsLinked to original sources
PubMed1998

Characteristics of phenol. Instillation in intralesional tumor excision of chondroblastoma, osteoclastoma and enchondroma.

Because of the typical metaphyseal-epiphyseal growth of giant cell tumors and chondroblastomas, the optimal result of an en bloc resection can usually only be achieved by a loss of joint function. For this reason, intralesional excision has prevailed, though it leads to a high rate of relapses. Adjuvant therapy involving irrigation of the remaining bone cavity with phenol can distinctly decrease the rate of relapse. Little is known about the amount of phenol applied that is absorbed. This study investigated the urinary excretion of phenol following the instillation of 102 ml of a 5% phenol solution. The method consisted of urine collection from 11 patients treated by phenol instillation preoperatively, and at 1, 3, 6, 12 and 24 h postoperatively. The urine specimens were analysed for phenol by mass spectrometry. Preoperatively, the value was 5.1 mg/l on average. The maximum concentration of 62 mg/l was found 1 h after instillation, with an average value of 41.5 mg/l, and after 3 h of 18.9 mg/l. A further rapid decrease in the excretion rate was recorded, with normal values being reached after 12 h. This means a maximum of 9% and an average of 2% of the instilled amount of phenol were excreted in the urine within 24 h postoperatively. By comparing these urinary concentrations to published standards, we conclude that the instillation of a 5% phenol solution into bony lesions is associated with a relatively low risk of systemic toxicity.

Adult↗
PubMed1997

Shear and tensile strength of hydroxyapatite coating under loading conditions. An experimental study in dogs.

The shear and tensile strength of a hydroxyapatite (HA) coating on a femoral component was studied after physiological loading conditions in 8 German Shepherds. A proximal macrostructure on the stem was used to protect this region from shear stresses. Another four implantations with uncoated components were used as controls. In vitro testing of the HA layer demonstrated excellent tensile strength and stability to surface deformation. The loaded implants were tested at 6, 12, and 24 weeks. At 6 weeks the HA-coated components could easily be removed by axial loading, whereas the HA layer remained undamaged on the metal. However, pull out tests of implants older than 12 weeks showed complete debonding of the HA layer from the non-macrostructured surface due to shear forces in all cases. Debonding of the HA layer was also observed with microradiography. The macrostructured surface prevented dislodging of the component from this area at pull out test by distributing shear forces. Unlike in uncoated implants, considerable amounts of bone remained attached onto the HA macrostructure when the surrounding femur was pulled out. Shear forces cause debonding of the HA layer, while tensile stress affects failure within the bone. Physiological loading partially produces gaps at the interface so direct transmission of tensile forces onto the bone is lost, and the coating-metal interface becomes the weak point in the system.

Animals↗
PubMed1997

The mechanism of loosening in cemented hip prostheses determined from long-term results.

Analysis of the mechanisms of loosening of cemented stems by radiological long-term follow-up in 129 cases. The most important finding was the failure of the cement-metal interface (29.5%), which was correlated significantly with osteolysis (31%). This suggests that the polyethylene debris reaches the bone through defects in the cement mantle (76.7%). In fact, the appearance of cement defects matches the number of identified osteolyses. This study shows that no permanent fixation can be achieved by the surface roughness of 2.0 microns Ra tried herein.

Adult↗
PubMed1997

[Process and outcome quality in giant cell tumor in relation to surgical management].

Giant-cell bone tumors display a locally aggressive growth pattern, frequently recur if no adjuvant treatment is given, and may potentially metastasize. By virtue of their biological behavior and typically juxta-articular localization, giant-cell bone tumors require specific surgical management. Thus, an intralesional tumor excision must be supplemented by adjuvant bone cementing, possibly combined with instillation of phenol or cryotherapy. These combined treatment modalities assure a high-quality procedure, defined as the actual way medical care is delivered, by promoting the quality of the outcome, defined as the effect of a medical procedure on the patient's state of health.

Adult↗
PubMed1997

The frequency, prognosis and significance of nerve injuries in total hip arthroplasty.

Although the incidence of post-operative nerve palsy after total hip replacement is rare, it is an important complication for the patient. In a retrospective study the results of 2713 hip arthroplasties were reviewed. Sixty-one cases (2.24%) of post-operative neuropathy were identified. 13 of the sciatic nerve, 33 of the peroneal nerve and 15 of the femoral nerve. The risk is significantly higher in revisions (3.06%), especially when exchanging the acetabular component (8.5%) rather than in primary arthroplasties (2.13%). After an average period of 107 months (11-240) from operation, 41 patients with nerve lesions were questioned about their subjective functional capacity: 17% had recovered completely, 39% had noticed an improvement, and in 44% there was no change; 56.1% complained of weakness and had a complete paralysis. In all cases there was dysfunction of sensibility. Another 17.1% had a sensibility defect without weakness. There was pain in 51.2%, paraesthesia in 34.1% and areas of complete anaesthesia in 19.5%. Altogether 61% of the 41 patients had either gait problems or were dependent on orthotic devices. In summary, only about a third of the patients studied achieved a satisfactory degree of functional recovery.

Female↗
PubMed1997

The rat myosin myr 5 is a GTPase-activating protein for Rho in vivo: essential role of arginine 1695.

myr 5 is an unconventional myosin (class IX) from rat that contains a Rho-family GTPase-activating protein (GAP) domain. Herein we addressed the specificity of the myr 5 GAP activity, the molecular mechanism by which GAPs activate GTP hydrolysis, the consequences of myr 5 overexpression in living cells, and its subcellular localization. The myr 5 GAP activity exhibits a high specificity for Rho. To achieve similar rates of GTPase activation for RhoA, Cdc42Hs, and Rac1, a 100-fold or 1000-fold higher concentration of recombinant myr 5 GAP domain was needed for Cdc42Hs or Rac1, respectively, as compared with RhoA. Cell lysates from Sf9 insect cells infected with recombinant baculovirus encoding myr 5 exhibited increased GAP activity for RhoA but not for Cdc42Hs or Rac1. Analysis of Rho-family GAP domain sequences for conserved arginine residues that might contribute to accelerate GTP hydrolysis revealed a single conserved arginine residue. Mutation of the corresponding arginine residue in the myr 5 GAP domain to a methionine (M1695) virtually abolished Rho-GAP activity. Expression of myr 5 in Sf9 insect cells induced the formation of numerous long thin processes containing occasional varicosities. Such morphological changes were dependent on the myr 5 Rho-GAP activity, because they were induced by expression the myr 5 tail or just the myr 5 Rho-GAP domain but not by expressing the myr 5 myosin domain. Expression of myr 5 in mammalian normal rat kidney (NRK) or HtTA-1 HeLa cells induced a loss of actin stress fibers and focal contacts with concomitant morphological changes and rounding up of the cells. Similar morphological changes were observed in HtTA-1 HeLa cells expressing just the myr 5 Rho-GAP domain but not in cells expressing myr 5 M1695. These morphological changes induced by myr 5 were inhibited by coexpression of RhoV14, which is defective in GTP hydrolysis, but not by RhoI117. myr 5 was localized in dynamic regions of the cell periphery, in the perinuclear region in the Golgi area, along stress fibers, and in the cytosol. These results demonstrate that myr 5 has in vitro and in vivo Rho-GAP activity. No evidence for a Rho effector function of the myr 5 myosin domain was obtained.

Actins↗
PubMed1996

Cytotoxicity of phenol to musculoskeletal tumours.

Local treatment with phenol is often used after intralesional excision of chondroblastomas and giant-cell tumours which involve bone near joints, and has been shown to reduce the rate of recurrence. The ideal concentration of phenol is uncertain, but may be important because of the high rate of absorption and toxicity. We have studied the effectiveness of different concentrations on standard sarcoma cell lines. Our results suggest that a 5% solution of phenol is effective against dispersed single cells, and that higher concentrations give no significant advantage, but create problems due to lack of homogeneous mixing, temperature and safety.

Bone Neoplasms↗
PubMed1995

Localization of the rat myosin I molecules myr 1 and myr 2 and in vivo targeting of their tail domains.

Myr 1 is a widely distributed mammalian myosin I molecule related to brush border myosin 1. A second widely distributed myosin I molecule similar to myr 1 and brush border myosin I, called myr 2, has now been identified. Specific antibodies and expression of epitope-tagged molecules were used to determine the subcellular localization of myr 1 and myr 2 in NRK cells. Myr 1 was detected at the plasma membrane and was particularly enriched in cell protrusions like lamellipodia, membrane ruffles and filopodia. In dividing cells myr 1 localized to the cleavage furrow. Myr 2 was localized in a discrete punctate pattern in resting cells and in cells undergoing cytokinesis. In subcellular fractionation experiments myr 1 and myr 2 were both partly soluble and partly associated with smooth membranes of medium density. The tail domains of myosin I molecules have been proposed to interact with a receptor and thereby determine the subcellular localization. To test this hypothesis we expressed the tail domains of myr 1 and myr 2 that lack the F-actin-binding myosin head domain in NRK cells. These tail domains also partly copurified with smooth membranes of medium density and immunolocalized similar to the respective endogenous myosin I; however, they exhibited a lower affinity for membranes and an increased diffuse cytosolic localization. These results suggest that the tail domains of myr 1 and myr 2 are sufficient for subcellular targeting but that their head domains also contribute significantly to maintaining a proper subcellular localization.

Actins↗
PubMed1994

Quality of bone transplantation procedure in West German orthopaedic hospitals.

We examined the impact of standardisation of allogenous bone transplantation according to the HIV protection guidelines on procedure quality using a questionnaire. As far as preparation, storage temperature and safety of the transplant are concerned, we showed an improvement in comparison to previous records. Hepatitis C testing has fallen although it is currently being recommended. According to the risk estimate for donors over 60 years the 3-months HIV test was considered unnecessary and was carried out in only 50% of transplants. In 4.5% of transplants no precautions against HIV transmission were taken.

AIDS Serodiagnosis↗
PubMed1989

Long-term results of the Girdlestone hip.

The Girdlestone hip is a possible alternative in cases where reconstruction and reimplantation appear hopeless. Only a minority of the 22 patients we followed for up to 16 years have had results ranging from good to satisfactory.

Aged↗
PubMed1986

[Management strategy in severe craniocerebral trauma in a general surgical department].

Emergency treatment of severe head injury combined with multiple trauma in most cases must be performed in regional hospitals and in general surgical units. Especially in acute intracranial hemorrhage (epidural hematoma) with the urgent indication to craniotomy the transmission of the patient in a special neurosurgical department is not possible in an adequate time. Therefore general surgeons should be trained in emergency trepanation of the skull and in basic treatment of severe head injury including measuring of intracranial pressure. The tactics of treatment of severe cranio-cerebral trauma is demonstrated on 46 cases out of 869 patients with head injury treated in our hospital from 1981 to 1984.

Adult↗
PubMedDate not supplied

[Analysis and assurance of complete medical documentation].

A written report on the findings of the examination forms the basis for the further procedure in the treatment of a patient--not merely in the area of orthopaedics. The examination findings should, therefore, be legible, readily understandable and complete. On the basis of 600 individual findings established at admission in the case of inpatients with diseases of the spine and hip, stemming from a total of three hospitals, the behaviour pattern of the individual examiner is analysed along with deficiencies in documentation. For a number of significant deficits, differences in the particular emphasis applied by individual physicians during the examination, the fact that the time available for such examinations is usually limited, and the lack of documentation system, are probably responsible.

Data Collection↗
PubMedDate not supplied

[Assurance and proof of satisfactory and complete information].

To prevent unjustified blame and claims enforced by patients, is necessary to prove evidence of an indisputable and complete preoperative information. With the help of our developed software it takes little effort to satisfy the given demands.

Female↗
PubMedDate not supplied

[Bone transplantation and AIDS].

The necessary obligation to carefulness at homogeneous transplantation of bone in concern of the AIDS epidemiology are being presented. According to the actual state of the HIV epidemiology a single examination of femur head donors contains an almost unmeasurable small risk of a virus transmission. Prior condition to an examination of the donor and to the usability of bones is the informed consent of the donor. Also important is the education of the recipient about the remaining risk, a provable documentation and a continuous observation of the HIV epidemiology.

AIDS Serodiagnosis↗