Laboratory evaluation of tissue heart valves. A comparative assessment.

Tissue of commercially prepared tissue heart valves were evaluated and compared with aluminium treated, fixed porcine valve tissue in vitro (tensile strength, scanning and transmission electron microscopy) and in vivo (calcification potential after subcutaneous implantation in the rat model). Valve leaflets (n = 40) were divided into four groups according to the method of treatment: Group I (fixed in 0.652% glutaraldehyde, control), Group II (fixed and treated with aluminium), Group III (fixed and treated with Toluidine blue) and Group IV (fixed and treated with watersoluble alkyl sulphate). Tensile strength was not influenced in Group II and III (p > 0.05). Group IV indicated a significant (p < 0.05) reduction in tensile strength. Scanning electron microscopy revealed damage and loss of surface endothelium in Group III and IV respectively. Transmission electron microscopy indicated damage to underlying matricial cells in Group III and IV. Calcification potential was significantly (p < 0.001) reduced in Group II to IV. We conclude that damage ultrastructure could contribute to the reduced tensile strength in Group IV and that reduced tensile strength might have an influence on the long-term durability of tissue heart valves. Antimineralization treatment of tissue heart valves does retard calcification but is yet unable to inhibit the process completely.

Lenticular chalcosis--electron microscopic and microprobe analysis. A case report.

A patient with a retained intra-ocular foreign body had a lens extraction for lenticular chalcosis. The lens capsule, examined under an electron microscope, showed copper particles deposited in the basement membrane. The lens capsule and foreign body were examined with an electron microprobe beam. This method proved to be an efficient method of qualitative and quantitative analysis of the contents of the foreign body.

The sensitivity of tests to detect in vivo platelet activation induced by the removal of arterial endothelium of the baboon (Papio ursinus).

The relative sensitivities for the various in vivo and in vitro tests for platelet activation are unknown. This was studied in a baboon model where limited and more substantial injury to the vascular endothelium was inflicted. The endothelium of a segment of the right carotid artery was removed with a balloon catheter on day 0 (limited de-endothelialisation), and that of the left carotid artery, abdominal aorta and left femoral artery on day 7 (substantial de-endothelialisation). Eight baboons (Papio ursinus) were used. Baseline tests for platelet activation (platelet volume, platelet density, platelet aggregate ratio, and platelet and plasma levels of platelet factor 4 [PF4] and beta-thromboglobulin [beta-TG]) were performed 7 days before de-endothelialisation and repeated on days 1, 9 and 16. The kinetics of indium-111-labelled platelets were measured after substantial de-endothelialisation. Sham operations were done on 3 animals exactly as in the test, except that the balloon injuries were not inflicted. No influence on the results of the platelet function tests was found. The only test capable of detecting limited injury to the endothelium was the measurement of plasma PF4. The mean platelet life-span (MPLS) shortened, mean platelet density decreased, the circulating platelet aggregate ratio decreased, and plasma levels of PF4 and beta-TG increased (P less than 0.05 in all instances) after the substantial endothelial injury. The mean platelet volume, intraplatelet PF4 and beta-TG, and the in vivo distribution and sites of sequestration of labelled platelets were poor tests for in vivo platelet activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Paired membrane-filament complexes in an acoustic neuroma.

An acoustic neuroma that developed in the posterior fossa of a 43-year-old black man was studied ultrastructurally. Unusual paired membrane-filament complexes were noticed in the cytoplasm of many tumor cells and appeared as multilayered parallel and concentric arrays in various planes of section. The paired membranes were found to be discontinuous with other membrane systems of the tumor cells. The cisternal space measured 25 nm across and housed a regularly arranged, single file of filaments 9 nm in diameter spaced 12 nm apart. In view of the biologic significance and possible origin of these structures, the paired membrane-filament complexes are morphologically compared with the myelin sheaths and cytoplasmic processes in this tumor.

The effect of potassium phosphate, magnesium chloride and T6 as blocking reagents on tissue valve calcification.

Potassium phosphate, Magnesium chloride and T6 as blocking agents on tissue valve calcification have been studied in vitro and in vivo. In vitro tests indicate that untreated leaflets (control group) tend to calcify significantly more than treated leaflets (p less than 0.05). Calcification in the treated leaflets tends to be varied with no significant difference (p greater than 0.05) between the different groups. In vivo findings indicate that leaflets in the control group calcify as early as 5 weeks after implantation while treated leaflets showed no significant signs of calcification at this stage. Results deduced from the extractable calcium contents as well as from histological examination, emphasise the need of a blocking reagent to decrease calcification on a valvular bioprosthesis.

[Renal cell carcinoma with a spindle-cell element--sarcomatous or sarcomatoid?]. / Renaalselkarsinoom met 'n spoelvormige selelement--sarkomateus of sarkomatoïed?

In this study the light microscopic and electron microscopic findings in two renal cell carcinomas with spindle-cell elements are described. The ultrastructural features of the spindle-cell element of sarcomatoid renal cell carcinoma have previously been documented, namely pentalaminar desmosomes, basal lamina formation and intracytoplasmic lumina with microvilli. The electron microscopic findings in the 2 cases described here showed mesenchymal rather than epithelial differentiation. It would appear that some renal cell carcinomas with a spindle-cell element are true carcinosarcomas, rather than sarcomatoid renal cell carcinoma.

Ultrastructural morphometric observations on serial sectioned human blood platelet subpopulations.

The relationships between the volume of human platelets and their cytoplasmic organelles were studied by morphometric analysis. Platelets were separated into four density-dependent subpopulations on an arabino-galactan gradient. In vitro activation of platelets was effectively prevented by maintaining them at a constant ambient temperature of 37 degrees C. Serial sections were cut through platelets, morphometrically analyzed and the platelets reconstructed. The volumes of the individual platelets and their constituent granules, mitochondria and open canalicular systems (OCS) were calculated. Individual organelles were counted. The mean volumes of the platelets of the subpopulations decreased significantly as density decreased (p = 0.01). Also, as the density of platelets decreased, there was a decrease in the mean unit volume of their granules (p = 0.003). In contrast, independent of platelet volume or density, the OCS occupies about 10% of the platelet volume. These findings indicate that it is possible to prevent in vitro platelet activation by maintaining their environment at 37 degrees C. Our study confirms the direct relationships between platelet volume and density; and platelet density and granule content. There is no ready explanation for the constant relationship between platelet volume and that of the OCS.

Placental site trophoblastic tumour (trophoblastic pseudotumour). A case report.

The term 'gestational trophoblastic disease' includes hydatidiform mole (invasive and non-invasive), choriocarcinoma and a rare condition initially called trophoblastic pseudotumour and more recently placental site trophoblastic tumour. Originally this condition was viewed as benign, but recent reports indicate that it may be fatal. The first report of a South African patient with this uncommon condition is presented.

The influence of the 'collection injury' on the survival and distribution of indium-111-labeled canine platelets.

The extent of the 'collection injury' sustained by platelets during labelling with In-111-oxine was investigated in three matched pairs of beagle dogs. The influence of the procedure on the survival, kinetics, in vivo distribution and fate of the labelled platelets was determined by serial blood sampling and quantitative computerized scintillation camera studies. Injured labelled platelets were removed in the matched dog acting as a biological filter. The survival, distribution and fate of the 'filtered' and 'unfiltered' platelets were compared. The mean platelet lifespan of the 'filtered' and 'unfiltered' platelets did not differ significantly, but the shape of the survival curve of the filtered platelets fitted a linear function more closely than that of the unfiltered platelets. Radioactivity in the different organs and regions was serially quantitated and expressed as a percentage of whole body radioactivity. Splenic and hepatic radioactivity of filtered and unfiltered platelets did not differ significantly at equilibrium or at the end of platelet lifespan. It is concluded that the currently employed isolation and labelling techniques for platelets are suitable for quantitative in vivo studies with a computerized scintillation camera system. The shape of platelet survival curves should, however, be interpreted with some caution as it may be influenced by these procedures.

[The sick cilia syndrome]. / Siek-siliasindroom.

The incidence of bronchiectasis should decrease because of improved immunization, but certain defects would still cause the malady. Fifteen consecutive patients with bronchiectasis were examined for ciliary defects by examining the nasal mucosae with an electron microscope and measuring the clearance of technetium-99m from the lung with a gamma camera. Three patients were found to have defects. Compound cilia, disorganization of the tubular structure, vacuolization and deficient inner dynein arms were observed. In one patient a loss of cell membranes which returned to normal after 4 months, was observed. Ciliary abnormalitites can either be anatomical or physiological and 'sick cilia' should be considered as a cause of bronchiectasis.

Preparation of a viable population of indium-111-labelled human blood platelets.

Factors influencing labelling of human platelets with 111Indium-8-hydroxyquinoline ([111In]-oxine) in a physiological saline medium were investigated. The efficiency of labelling is influenced by time of incubation, concentration of oxine, and pH of the incubating medium. It was found that a viable platelet population could be labelled under the following conditions: (1) centrifugation of platelet rich plasma in polystyrene conical tubes at 800 g for 15 min; (2) resuspension of the platelet pellet in saline, pH 5.5; (3) incubating for 30 min at 22 degrees C with [111In]-oxine at a concentration of 6.25 mg oxine/litre platelet suspension; (4) washing once with platelet poor autologous plasma (PPP); and (5) finally resuspending the platelets in PPP. The labelled platelets aggregated normally with collagen and ADP. Electron microscopy, done immediately after labelling, showed internal organelle reorganization characteristic of activated platelets. These ultrastructural features were reversible on incubation in PPP at 37 degrees C for 30 min. The 111In is not released from aggregated platelets and the label does not elute from incubated platelets for at least five hr. We conclude that human platelets thus labelled are suitable for in vivo kinetic studies.