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Biomedical subjects

C P Klein

Publications and source records attributed to C P Klein.

72 records · Page 4Linked to original sources
PubMed1980

Interaction of some serum proteins with hydroxylapatite and other materials.

In order to investigate whether the immune system is involved in the degradation of hydroxylapatite as implant material the adsorption behavior of several serum proteins to hydroxylapatite was studied and compared with the adsorption to other calcium phosphate compounds (Ca3(PO4)2, CaHPO4), calcium carbonate, aluminium oxide, and zinc oxide. It was found that complement factors, C4 and C3, and alpha 2-HS-glycoprotein adsorbed to the calcium phosphate compounds, but not to the other materials. IgG and albumin were adsorbed to all investigated compounds. These results suggest that the complement factors are directly adsorbed on the surface of the calcium phosphate compounds. Therefore, the activation of complement, if any, proceeds by the classical pathway. The binding of complement factors to the calcium phosphate salts investigated points to a more specific involvement of the immunosystem in the degradation process of calcium phosphate implants.

Adsorption↗
PubMed1979

[Spontaneous coronary spasm with reversible occlusion of the left coronary artery: a case report (author's transl)].

A spontaneous coronary spasm with a complete but reversible occlusion of the left coronary artery could be demonstrated by coronary arteriography in a patient with angina pectoris at rest and during exercise. This will prove that spasms of coronary arteries can cause angina pectoris or even acute myocardial infarction if the spasm is persisting for long enough and if there is no sufficient supply by collateral vessels. This can be a possible reason for akinesia or dyskinesia of the left ventricle associated with normal or near normal coronary arteries.

Angina Pectoris↗
PubMed1978

Radioisotopic diagnosis and quantitation of left to right shunts in childhood and adolescence.

In 187 patients (141 adults and 46 children) left to right shunts were assessed using quantitative radionuclide angiography. After injection of 99mTc into the femoral vein time activity curves were registered over both lungs and the heart (Ohio Nuclear Camera, ON SIGMA 400, 110, HP 5407 computer). Using a modified gamma function area ratio technique the shunt sizes were calculated. The radioisotopic method allows a precise quantitation of left to right shunts ranging from 15--80%. There was a good agreement between the shunt sizes calculated by the radioisotopic method and oximetry or dye-dilution at cardiac catheterization (adults r = 0,87, children r = 0,85). The shunts sizes assessed with this nontraumatic method appear sufficiently reliable to be a real alternative to conventional techniques in screening for shunts.

Adolescent↗
PubMed1978

[Nuclear medical estimation of ejection fraction, cardiac output and time volume-differentials (author's transl)].

Gated blood pool investigation yield the ejection fraction as ratio of two volumes. To obtain absolut volumina (e.g. output volume in ml) the authors utilize the first transit of the tracer through the heart cava. Radionuclide output of the heart equals input during the first tracer passage, homogeneous infusion of the tracer provided. The resulting calibration factor makes possible the calculation of the stroke volume in the gated bloodpool procedure. Good correlation could be proven in 35 patients (r = 0.86 and 0.9, respectively).

Cardiac Output↗
PubMed1977

[Clinical aspects of pulmonary arteriovenous fistulas (author's transl)].

3 patients with a congenital pulmonary arteriovenous fistula are presented. The clinical signs of this condition are dependent on the size of the functional right to left shunt. The symptoms worsen with increasing arterial hypoxemia. Due to the hemodynamics of arteriovenous fistulas signs of cardiac hypertrophy are usually not seen on ECG of X-ray examination. However, in almost all cases pulmonary X-ray shadows are found. In addition, nearly 50% also have an hereditary hemorrhagic telangiektasis. The diagnosis must be verified in every case by cardiac catheterisation with angiography, since only exact anatomic data can give precise information on whether or not an operation is possible.

Adult↗
PubMed1977

[Diagnosis and quantiation of left to right shunts using radioisotopes].

After intravenous injection of 99mTcO-4 into the femoral vein the count-rate vs. time curve of a lung field is recorded and analysed (Ohio Nuclear Camera ON 110, pdp 11 computer GAMMA 11, hp 5407 computer). Using a modified gamma function area-ratio technique, the size of the left to right shunts is calculated and compared with cardiac catheter results (128 patients). The localisation of the left to right shunt (ASD or VSD) is possible, if the shunt size rises over 30%. The method may be an alternative to oximetry and conventional dilution techniques.

Adolescent↗
PubMed1976

[Hormon producing tumors of the pancreas. Verner-Morrison like symptomatology of a non-serotonin-producing, metastasizing carcinoid of the pancreas (author's transl)].

A case of Verner-Morrison like symptomatology of an histological identified, metastasizing, non-serotonin-producing carcinoid of the pancreas is described. The likeness of symptomatology to courses of disease by islet-cell tumors is pointed out, the coincidence of carcinoid and islet-cell-tumors and their common origin are discussed.

Carcinoid Tumor↗
PubMedDate not supplied

Cortical bone ingrowth in growth hormone-loaded grooved implants with calcium phosphate coatings in goat femurs.

Dental implants are successfully used for tissue-integrated protheses, but the long-term survival in the maxilla is shorter than in the mandible [Cune MS, Thesis, University of Utrecht, 1993; Jaffin RA, Berman CL. J Periodontol 1991;62:2-4]. However, by adding growth hormone at implantation, increased bone apposition may be expected, since it is known that growth hormone has a stimulating effect on the differentiation and proliferation of osteoblastic cells [Ernst M, Froesch ER. Biochem Biophys Res Commun 1988;151:142-47; Scheven BAA et al. Growth Regul 1991;1:160-67; Stracke H et al. Acta Endocrinol 1984;107:16-24]. We studied bone ingrowth and bone contact of grooved implants impregnated with growth hormone in the cortex of femurs of female goats. We compared the effect of growth hormone on grooved implants with or without calcium phosphate coatings at the bottom of the grooves. The coatings used were hydroxyapatite, fluorapatite and heat-treated hydroxyapatite. The implants had both small and large grooves. The implants were positioned in the cortex of one femur and were treated with recombinant human growth hormone, while the implants on the opposite femur served as controls. After 6 weeks, the implants and surrounding tissues were dissected and evaluated histomorphologically and morphometrically by light microscopy. The bone ingrowth and the bone contact in the grooves were quantified by digital image analysis. Calcium phosphate coating at the bottom of the grooves resulted in a significant increase of bone ingrowth and bone contact. Small grooves had significantly more bone ingrowth and bone contact than the larger grooves. However, all implants impregnated with growth hormone showed inhibition of bone contact and bone ingrowth. We conclude that recombinant human growth hormone inhibits bone formation in the grooves coated with calcium phosphate. Without the addition of growth hormone, the calcium phosphate coatings improved bone ingrowth and bone contact in the grooves. Further studies are required to determine whether growth hormone could also possibly act as a bone growth promoting factor in these implants.

Alloys↗
PubMedDate not supplied

Tracheal reconstruction with hydroxyapatite tracheal prosthesis.

A porous hydroxyapatite tracheal prosthesis was implanted in rabbits after resection of a 15 mm circular segment of the cervical trachea. Postoperatively the animals were followed by radiography, bronchoscopy, and microscopy at the time of autopsy. The longest survival time was 22 weeks. All the rabbits died of infection at the prosthetic site or of progressive stenosis at the anastomoses. The prosthesis was incorporated by surrounding tissues, but no overgrowth of ciliated epithelium on the luminal surface of the prosthesis was observed. Although a hydroxyapatite tracheal prosthesis is tolerated in rabbits, covering of the luminal surface of the prosthesis with a non-porous layer to prevent infection and to permit mucosal overgrowth is necessary to achieve better long-term results.

Animals↗
PubMedDate not supplied

Behavior of calcium phosphate coatings with different chemistries in bone.

Calcium phosphate ceramic coatings with a hydroxyapatite chemistry applied on the surface of dental implants eliminate the need for initial mechanical retention and decrease the time necessary for bonding the implants to the bone. Hydroxyapatite-coated implants retrieved from patients were found to be compatible and to have bonded strongly to the bone, but the coatings showed thinning because of partial or total loss of coating material. This study compared the behavior in bone of newly developed fluorapatite and heat-treated hydroxyapatite coatings, with the clinically used hydroxyapatite coatings used as controls in experimental studies in dogs. The biologic responses to fluorapatite and heat-treated hydroxyapatite coatings were the same as those to hydroxyapatite coatings, and bone condensation around all coatings was histologically evident. However, the coating thickness of the fluorapatite and heat-treated hydroxyapatite coatings remained stable with only minor changes during the observation period of 24 months.

Absorptiometry, Photon↗