PubMed Health⌕ Search

Biomedical subjects

M Meenaghan

Publications and source records attributed to M Meenaghan.

9 recordsLinked to original sources
PubMed1993

Antibodies to platelet glycoprotein V in polytransfused patients with haematological disease.

Polytransfused patients often develop platelet-reactive antibodies (PRAb). These give positive reactions in the platelet immunofluorescence test (PIFT) and may be either lymphocytotoxic (LCTAb) or platelet-specific antibodies (PSAb). The latter may be detected in the PIFT using chloroquine-treated platelets (Chl-PIFT) or by immunoblotting. Serial samples from 106 multiply transfused patients with bone marrow failure were screened by PIFT using a microplate method and flow-cytometric analysis. PSAb activity was confirmed by Chl-PIFT. In 45 (42%) of the patients studied PSAb were detected; 37 (35%) formed LCTAb and 19 (51%) had co-existent PSAb. Sera from 25 of 27 patients with a positive Chl-PIFT, retested by immunoblotting, recognised determinants of Mr 82-160 kD on whole platelets. A large group became sensitised to a component of Mr 105-115 kD reduced (99 kD non-reduced) with similar electrophoretic mobility to GPIIIa using a monoclonal anti-GPIIIa and two human polyclonal anti-HPA-1a sera; some also produced anti-GPIIb. The largest group recognised a determinant of Mr 80-83 kD, probably glycoprotein V (GPV). Three sera were immunoblotted against thrombin-treated platelets and the results confirmed GPV specificity.

Adolescent↗
PubMed1990

Platelet concentrates irradiated with ultraviolet light retain satisfactory in vitro storage characteristics and in vivo survival.

We have previously reported that platelet concentrates (PC) may be irradiated with ultraviolet light (UVL) in a cryostorage pack such that mixed lymphocyte reactions (MLR) are abolished whilst satisfactory platelet function is retained during subsequent storage using Fenwal PL-1240 containers. We have now studied both platelet structure and function after irradiation in DuPont Stericell bags which are both UV-permeable and biocompatible. The irradiation dosage was 3000 Joules/m2 of UVL at a mean wavelength of 310 nm; a dose previously shown to abolish MLR. No detriment to platelet function was observed when compared to control as measured by aggregation responses to adenosine diphosphate (ADP), collagen and ristocetin, hypotonic shock response and pH during 5 d of storage. Lactate levels were significantly higher (P less than 0.01) and glucose levels lower (P less than 0.01) in UV-treated PC, although in the majority the lactate level did not exceed 20 mmol/l. Betathromboglobulin and platelet factor 4 levels were higher during storage in the UV group, the latter reaching significance (P less than 0.05). When whole platelets and platelet membranes were stained with Coomassie blue or Periodic Acid-Schiff's reagent after electrophoresis in polyacrylamide gels no obvious alterations to major membrane constituents were observed on days 1 and 5 of storage. Paired in vivo autologous studies in healthy volunteers using 111Indium-labelling were performed at the end of 5 d of storage. The UV-treated platelets gave satisfactory and equivalent results for recovery, half life and survival when compared to controls. We conclude that PC irradiated with UVL and stored for 5 d in DuPont Stericell containers appear suitable for transfusion and may prove to be nonimmunogenic. Further in vivo studies of haemostatic efficacy and recipient alloimmunization are now warranted.

Blood Platelets↗
PubMed1989

Lectin histochemistry of ameloblastomas and odontogenic keratocysts.

The cell membrane carbohydrate components of 10 simple (follicular and/or plexiform pattern) and 5 acanthomatous ameloblastomas, one plexiform unicystic ameloblastoma, one soft tissue ameloblastoma and 11 odontogenic keratocysts were studied in paraffin-embedded tissues using horseradish peroxidase-conjugated lectins. The presence of glucose and mannose was demonstrated by intense labelling with Concanavalin ensiforme (Con A) in 73% of the ameloblastomas examined, while periodate oxidation of the specimens prior to Con A (PA/Con A) stained 53% of the cases. Ameloblastomas did not express receptors for Triticum vulgaris (WGA), Erythrina chrystagalli (ECA), Arachis hypogea (PNA), and Ulex europaeus (UEA-1). The plexiform unicystic ameloblastoma and the soft tissue ameloblastoma examined showed the same cell membrane glycoproteins as the simple and acanthomatous ameloblastomas. Forty-five per cent of the keratocysts demonstrated Con A reactivity from the basal to the keratinized layer, while 72% of these specimens showed positive PA/Con A reactivity from the parabasal to the keratinized layer. Staining with WGA, ECA, PNA, and UEA lectins also revealed the presence of N-Acetyl-glucosamine and fucose oligosaccharides in the plasma membrane of basal, spinous and keratinized cell layers of the odontogenic keratocysts. The distinct cell surface carbohydrate composition of the ameloblastoma and odontogenic keratocyst may be responsible for the differences in biological behavior in these conditions.

Adolescent↗
PubMed1988

Gastric bleeding in pseudoxanthoma elasticum.

We report a case of pseudoxanthoma elasticum and gastrointestinal bleeding, and document the degenerative changes of the gastric arterioles occurring over a 26-yr period. In addition to the internal elastic lamellar degeneration and dystrophic calcification, we describe the presence, ultrastructurally, of an abnormal collagen fiber. These degenerative changes in the gastric vascular bed can be a direct cause of gastrointestinal bleeding.

Gastrectomy↗
PubMed1985

Temperature sensitivity of potassium flux into red blood cells in the familial pseudohyperkalaemia syndrome.

The temperature dependence of potassium flux into the red cells of normal and pseudohyperkalaemic individuals over the range 4-40 degrees C was measured using 86RbCl as tracer. Flux through the pump was measured as the ouabain-sensitive component (0.2 mM ouabain) and flux via Na+,K+-cotransport was measured as the decrease in the rate of K+ influx in the presence of 1 mM furosemide. The residual passive permeability of the red cell plasma membranes to K+ was that influx which was unaffected by either inhibitor. When Na+ influxes were measured, the ratio of Na+ to K+ transported via the furosemide-sensitive component was 1 over the full temperature range studied. The temperature sensitivity of K+ influx via the pump was normal as was the enzymic activity of the Na+,K+-ATPase. In contrast, the activity of the Na+,K+-cotransport system in pseudohyperkalaemics was more temperature sensitive than that of controls and affected individuals also showed a greater passive permeability to K+ at low temperatures. Red cell membranes from affected individuals have significantly increased amounts of phosphatidylcholine which are balanced, to a degree, by a decreased content of phosphatidylethanolamiane. It is proposed that in this example of familial pseudohyperkalaemia there is an alteration in the structure of the red cell plasma membrane which influences the temperature sensitivity of both its cotransport and passive permeability properties.

Biological Transport, Active↗
PubMed1982

Degradative effects of conventional steam sterilization on biomaterial surfaces.

Prior to implantation trials in animals, the effect of steam sterilization on the surface properties of metallic and coated biomaterials was studied. Pure germanium plates and cast surgical Vitallium discs and subperiosteal implants were treated to present three standard types of biomaterials surfaces prior to steam sterilization, ranging from scrupulously clean, high-energy metals to uniformly low-energy organic layers. Both before and after sterilization, the sample surfaces were characterized by a variety of nondestructive physiochemical techniques. The results indicate that steam sterilization is likely to compromise the properties of otherwise carefully prepared biomedical implants by depositing hydrophobic organic and hygroscopic salt contaminants over the implant surfaces.

Biocompatible Materials↗
PubMed1981

Histological evaluation of pore size and shape in silicone implants in rhesus monkeys.

Silastic has been used with varying success as an implant material. When Silastic implants fail, migration and infection are generally involved. Perforation of the implant has been suggested as a means of minimizing implant migration. In this study, 30 implants were studied in Rhesus monkeys. The implants varied in external geometric form and in perforation size. Results indicated that fibrous encapsulation of the implant occurred within two weeks. The tissue readily invaded the perforations regardless of pore size. The configuration of connective tissue was unaffected by external geometry. Perforated implants were less mobile than non-perforated implants, and implants with perforations of 3 mm or more contained dense fibrous connective tissue supported by an underlying vascular mesenchymal tissue not seen in implants with smaller pores. As a result of this study, we recommend that perforations be used in Silastic implants and that these perforations be at least 3 mm in diameter.

Animals↗