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Biomedical subjects

G Hotz

Publications and source records attributed to G Hotz.

At least 19 recordsLinked to original sources
PubMed1994

Bone substitute with osteoinductive biomaterials--current and future clinical applications.

In craniomaxillofacial surgery, possible indications for the use of osteo-inductive biomaterials are interposition in intraosseous defects, contour augmentation, and reconstruction of segmental defects. The experimental results in the field of bone morphogenetic protein (BMP) research within the last few years have shown that it is possible to combine osteoinductive proteins with suitable carrier materials to obtain new composite osteoinductive biomaterials. These carrier materials function as slow-delivery systems for BMP. By combination of BMP with different carrier materials such as various types of calcium phosphate ceramics, collagen or inactive collagenous bone matrix, and other organic and inorganic carriers, the biomaterial can be adapted to clinical demands in a wide range. In several experimental animal studies, we investigated nine different calcium phosphate ceramics and inactive rat bone matrix for their use as BMP carrier. All materials tested seem to be suitable carriers for BMP. The first clinical applications are discussed.

Animals↗
PubMed1992

Risk factors predicting operable intracranial hematomas in head injury.

A study was performed to examine the incidence of operable traumatic intracranial hematomas accompanying head injuries of differing degrees of severity, and to see if factors predicting operable mass lesions could be identified. Logistic analysis was used to identify independent predictors of operable traumatic intracranial hematomas. Data were gathered prospectively on 1039 patients admitted with head injury between January, 1986, and December, 1990. Patient age, Glasgow Coma Scale (GCS) score, pupillary inequality, and injury by falling were all independent predictors of the presence of operable intracranial hematomas (p = 0.0000, 0.0000, 0.0182, and 0.0001, respectively). Injury to vehicle occupants was less likely to result in operable mass lesions (p = 0.0001) than injury by other means. The incidence of traumatic intracranial hematomas in patients over 50 years old was three to four times higher than in those under 30 years of age. Not surprisingly, the incidence of operable hematomas increased with decreasing GCS scores. However, even at a GCS score of 13 to 15, patients with other risk factors had a substantial incidence of operable mass lesions. There was a 29% incidence of operable intracranial hematomas for patients with a GCS score of 13 to 15, aged over 40 years and injured in a fall. It is suggested that patients who are middle-aged or older, or those injured in falls, are at particular risk for traumatic intracranial hematomas even if their GCS score is high. These patients should have early definitive investigation with computerized tomography in order to identify operable hematomas and to initiate surgical treatment prior to neurological deterioration from mass effect.

Adolescent↗
PubMed1991

Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation. Part I: An experimental study.

Histological studies in animals have shown that fibrin sealant can be employed as a resorbable, biological binding agent for fixation of initially mouldable hydroxylapatite (HA) implants. Mixing HA granules with a 2 component fibrin sealant from which thrombin solution has been diluted to 1 IU/ml provides a simple method for obtaining mouldable implants. During insertion of the HA granules, the sealant prevents dislocation and migration, and on solidification, the moulded implant securely retains its shape and position until connective tissue ingrowth is complete. The use of polygonal granules permits a constant implant contour from the very beginning.

Alveolar Ridge Augmentation↗
PubMed1991

Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation. Part II: Clinical application.

The use of fibrin as a resorbable biological adhesive permits moulding of HA granules into individually shaped implants. The binder prevents dislocation of granules during delivery, and the moulded implants securely retain their shape until fibrous tissue ingrowth is complete. Three years of clinical experience have shown that, mouldable fibrin-bound HA has so far proved suitable as a bone substitute in preprosthetic as well as in plastic and reconstructive surgery.

Aged↗
PubMed1991

Relative incidence of intracranial mass lesions and severe torso injury after accidental injury: implications for triage and management.

In a previous study of head injury patients we found that old age, low Glasgow Coma Scale (GCS) score, pupillary inequality, and falls were significant predictors of intracranial mass lesions (IMLs). Injury to motor vehicle occupants was less likely to result in IML. The present study defines predictors of severe torso injury (STI) in 646 patients admitted to a trauma unit and compares these with predictors of IML obtained in the previous study. Tachycardia and low blood pressure were associated with an increased incidence of STI (p = 0.003, p = 0.0000). The incidence of STI in falls differed from that of IML (13.2% vs. 47.7%, p less than 0.001). There was a greater incidence of STI than IML in MVAs (33.6% vs. 14.8%, p less than 0.001). Patients 70 years of age or older had a higher incidence of IMLs than STIs (p less than 0.001). Patients less than 30 years old had a significantly greater incidence of STIs than IMLs (p less than 0.001). These data suggest that in MVA victims who are less than 30 years old, are hypotensive, and tachycardic, the diagnosis and emergent treatment of severe torso injury should take precedence over measures designed to detect and treat intracranial mass lesions. The converse is true for older patients injured in falls.

Abdominal Injuries↗
PubMed1989

Cellular aspects of retention and transport of inhaled soluble and insoluble actinide compounds in the rat lung.

The binding of 241Am-hydroxide polymers (as models for readily soluble actinide compounds) to the cell components of rat lung was investigated using differential centrifugation, density gradient centrifugation, gel chromatography, carrier-free electrophoresis and electron microscopic autoradiography (with 241Pu). Irregularly shaped and spherical mixed (U, Pu)O2 particles (as models for insoluble actinide compounds) were administered to rats by inhalation and intratracheal installation and the lung and organ retention was determined. Electron microscopic studies were performed with rat lung and with rat and bovine alveolar macrophages exposed to the actinide compounds in vitro. In the case of the mixed (U, Pu)O2 particles the lung retention was independent of the particle shape and route of administration. Whereas 241Am administered as a hydroxide polymer was transferred rapidly from lung to skeleton and liver, only a few percent of the initial alveolar deposit was found in these organs after mixed oxide inhalation. It is concluded that all types of particles are stored primarily within phagolysosomes of alveolar macrophages. In the case of readily soluble compounds, the actinides are solubilized within these lysosomes and become bound to cytosolic ferritin in the alveolar macrophages. They are then released from the macrophages and probably cross the alveolar membranes as transferrin or as low-molecular-weight forms. Insoluble compounds remain within the lysosomes of alveolar macrophages, but there are indications of chemical damage to the lysosomal membranes, causing the particles to lie free in the cytoplasm.

Actinoid Series Elements↗
PubMed1989

Behaviour of spherical and irregular (U,Pu)O2 particles after inhalation or intratracheal instillation in rat lung and during in vitro culture with bovine alveolar macrophages.

Spherical and irregularly shaped mixed (U,Pu) oxide particles were administered to rats by inhalation and by intratracheal instillation. The lung retention of the particles was independent of particle shape and of the route of administration. Only a small percentage of the administered radioactivity was found in other organs. Detailed electron microscopic studies showed particles within membrane-enclosed vacuoles as well as lying free in the cytoplasm.

Administration, Inhalation↗
PubMed1989

[Alveolar bone reconstruction with hydroxyapatite in aged humans].

There is a rising need for preprosthetic surgery due to a general increase in life expectancy and the desire for optimal oral rehabilitation. A method of reconstructing residual ridges in an ideal form with a hydroxylapatite-fibrin paste is presented. Patients suffering from mild to moderately severe age-related neurological disorders with dementia and psychomotor slowing benefit from the procedure, whereas psychiatric illnesses such as hypochondria or psychotic disturbances need to be excluded from ridge reconstruction. The same is true for neurological deficits resulting in facial and oral hyperkinesia.

Aged↗
PubMed1989

[Antiphlogistic effect of bromelaine following third molar removal].

A placebo-controlled double-blind study of 100 patients with impacted and/or dislocated lower wisdom teeth was conducted to examine the tolerance and antiphlogistic efficacy of bromelaine--a mixture of proteolytic enzymes from ananas comosus. Treatment was started 1 day prior to third molar surgery with a daily dose of 3 x 80 mg and was continued for a total of 6 days. On the 1st day following surgery, linear measurement (distance: tragus-pogonion) showed swelling to be 7.5% lower under drug treatment than in the placebo group. Two-dimensional image evaluation increased this difference to 15.9%, which however still failed to attain the significance level of 20%. Between the 3rd and the 7th postoperative day no differences were found between the two groups regarding the extent of soft tissue swelling or the speed of edema resolution.

Adolescent↗
PubMed1987

Association of plutonium with lysosomal, lipofuscin-like granules in Chinese hamster hepatocytes: evidence from electron microscopic and biochemical studies with 241Pu and 239Pu.

This electron-microscopic-autoradiographic study was undertaken to identify the cell organelles, which bind plutonium in Chinese hamster hepatocytes at different times after injection. Female Chinese hamsters were injected intraperitoneally with 241Pu and sacrificed at time intervals of between 4 days and 35 weeks. The Chinese hamster was chosen as the experimental animal as it is a species in which there is virtually no elimination of plutonium from the liver. From the 4th day onwards beta-tracks were found over globular electron-dense structures, which were randomly distributed in the cytoplasm of the hepatocytes and strongly resembled lipofuscin bodies. Comparison of the results with those from biochemical experiments showed good agreement between the morphological and biochemical observations. At early times after injection 241Pu was also found in the hepatocyte nuclei. All the evidence suggests that in this species plutonium in hepatocytes becomes bound to lipofuscin-accumulating lysosomes, which cannot be excreted.

Animals↗
PubMed1986

[Preventive lymphadenectomy in cutaneous malignant melanomas. A matched pair study].

Data on 70 patients with melanomas classified as clinical stage I, who had been treated surgically with wide excision (n = 49) or wide excision plus prophylactic lymph node dissection (n = 21) at the University Dermatology Clinic, Freiburg i. Br. between 1975 and 1977, were reviewed in a retrospective study. The effectiveness of elective lymph node dissection was examined by creating 21 pairs of patients, matched according to sex as well as to the level, location and thickness of the tumors (to within +/- 5%). One patient in each pair underwent wide local excision and prophylactic lymph node dissection (WE + PLND) to others did not (WE only). Depending on tumor thickness there was a better chance of survival for the PLND patient group. However, these differences were not statistically significant.

Female↗