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Biomedical subjects

R Garrett

Publications and source records attributed to R Garrett.

At least 37 records · Page 2Linked to original sources
PubMed1986

The effect of isoxicam-aspirin combinations on the polyurethane sponge implantation model in the rat.

1 Anti-inflammatory effects of isoxicam alone and in combination with aspirin were studied in rats using the polyurethane sponge implantation model of acute inflammation. 2 Dose-response studies were performed to delineate a suppressive (high) and non-suppressive (low) dose of isoxicam prior to studying these doses in combination with aspirin. 3 The results indicate that a combination of aspirin with isoxicam does not have an additive anti-inflammatory effect. 4 The interference demonstrated by aspirin with the anti-inflammatory effects of other NSAIDs such as indomethacin is also demonstrated with aspirin/isoxicam combinations.

Animals↗
PubMed1983

Effects of cobalt-chrome alloy wear particles on the morphology, viability and phagocytic activity of murine macrophages in vitro.

Metallic wear particles were prepared from orthopaedic cobalt-chrome alloy by milling in medium supplemented with 20% foetal calf serum to maintain particle dispersion. The size distribution of particles was determined by sedimentation and centrifugation and particle concentration was assessed using light extinction. Monolayers of mouse peritoneal macrophages were exposed to metal particles at different concentrations for varying periods. After 4 h of exposure to particle concentrations exceeding 30 micrograms/ml there was a progressive decline in cell viability, and light and electron microscopy showed that surviving cells had assumed remarkably smooth profiles and contained abundant endocytosed metal. Phagocytic uptake of polystyrene spherules was inhibited markedly by exposure to metal particles even at concentrations at which macrophages remained 100% viable, and preceded the reduction of viability at higher concentrations. The findings are consistent with a pathological role for the metallic wear particles observed frequently within macrophages in the synovial tissues around loose artificial joints in humans.

Animals↗
PubMed1983

The role of catheter surface morphology and extractable cytotoxic material in tissue reactions to urethral catheters.

Batches of urethral catheters associated with stricture formation during clinical usage were found to be amongst those causing marked acute and chronic inflammation after subcutaneous implantation in rats. The degree of inflammation did not correlate with the surface roughness of catheters assessed by scanning electron microscopy, but showed an excellent correlation with the cytotoxic effects of soluble extracts from catheters on macrophage monolayers in tissue culture. The findings suggest that stricture formation may be chemically induced and may not relate to surface roughness of catheters.

Animals↗
PubMed1983

Assessment of nonsteroidal anti-inflammatory drug combinations by the polyurethane sponge implantation model in the rat.

The anti-inflammatory effect of single doses and combinations of aspirin and commonly used nonsteroidal anti-inflammatory drugs was investigated by the polyurethane sponge implantation model of acute inflammation. Dose response curves were performed to delineate a suppressive (high) and nonsuppressive (low) dose of each drug prior to studying these doses in combination with aspirin. The results suggest that a combination of aspirin in either high or low dose does not increase the anti-inflammatory effect of other nonsteroidal anti-inflammatory drugs in this model of inflammation.

Animals↗
PubMed1983

Fibrinolytic effects of intracoronary streptokinase administration in patients with acute myocardial infarction and coronary insufficiency.

Serial coagulation studies were obtained in 25 patients treated with intracoronary streptokinase infusion for myocardial infarction (23 patients) or coronary insufficiency (two patients) to determine the frequency of systemic fibrinolytic activity. Clotting studies were obtained before and after infusion and at 4-hour intervals until normalization. Intracoronary thrombolysis was successful in 20 of 23 patients (87%) with myocardial infarction. Streptokinase dosage in this study was 201,000 +/- 74,000 IU (+/- SD). Systemic fibrinolytic activity, defined as greater than 70% reduction of fibrinogen using a functional assay (Claus method), occurred in 22 of 25 patients (88%) and was present at a mean streptokinase dosage of 119,000 +/- 52,000 IU. Fibrinogen in the total population decreased from 342 +/- 80 to 87 +/- 94 mg% (p less than 0.0001). In patients with systemic effect, the mean fibrinogen level after infusion was 17% of baseline, increased to 43% at 24 hours, and returned to normal at 30 hours. Plasminogen decreased to 7% of baseline activity after infusion (p less than 0.0001), was 44% of baseline at 24 hours, and returned to normal at 48 hours. Intraprocedural sampling during infusion showed reduction of fibrinogen by 25% after 30,000 IU (p less than 0.0005) and by 71% at 120,000 IU (p less than 0.0001); plasminogen decreased by 50% after 30,000 IU (p less than 0.0001) and by 84% at 120,000 IU (p less than 0.0001). Prothrombin time increased from 11.5 +/- 0.8 seconds to 22.0 +/- 7.8 seconds after infusion (p less than 0.0001) and returned to normal at a mean of 18 +/- 11 hours after infusion. Partial thromboplastin time was markedly prolonged (greater than 100 seconds) after infusion, returned to less than or equal to 2 times control at 5 +/- 2 hours, and returned to normal at 9 +/- 4 hours after infusion. Fibrinogen degradation products were less than 10 micrograms/ml before infusion, increased to greater than 40 micrograms/ml after infusion, and remained greater than 40 micrograms/ml in 40% of patients at 24 hours after infusion. These data indicate that systemic fibrinolytic activity occurs in a high percentage of patients with "low-dose" intracoronary streptokinase infusion and that coagulation variables may be altered for 24-48 hours after infusion.

Adult↗
PubMed1982

The primary structures of two leghemoglobin genes from soybean.

We present the complete nucleotide sequences of two leghemoglobin genes isolated from soybean DNA. Both genes contain three intervening sequences which interrupt the two coding sequences in identical positions. The 5' and 3' flanking sequences in both genes contain conserved sequences similar to those found in corresponding positions in other eukaryotic genes. Thus, the general DNA sequence organization of these plant genes is similar to that of other eukaryotic genes.

Base Composition↗
PubMed1982

Absence of metabolic bone disease in the proximal femur in patients with fracture of the femoral neck.

A clinical, radiological and histopathological study of femoral heads from 125 patients with fracture of the neck of the femur and from 30 cadavers was carried out to identify various risk factors. The findings showed that the Singh index was unreliable as a radiological indicator of the bone content of the femoral heads; that the bone content of the femoral head in patients sustaining a fracture of the femoral neck did not differ from that of the controls; that osteomalacia was not found in any of the heads examined; and that the distribution of trabecular microfractures did not support the hypothesis that fracture of the neck was the result of progressive fatigue. It was concluded that the single most important factor leading to fracture in this Australian population was injury caused by falls and that such injury was frequently associated with other disease processes.

Aged↗
PubMed1981

The ultrastructural features of malakoplakia.

The ultrastructural features of a case of disseminated malakoplakia are described and compared with available published cases. Generally macrophages were involved (although characteristic inclusions were seen in association with some plasma cells) and contained three types of cellular inclusions. These were (1) the phagolysosomes (2) and intermediate structure sharing features of the phagolysosome and the Michaelis-Gutmann (MG) body and (3) the MG body. All inclusions were delineated by unit membranes and their matrices (except those of large MG bodies) composed of membranous whorls and loops. It is suggested that these inclusions represent stages in the development of the MG body. Septate junctional complexes were observed between phagolysosomes and small MG bodies. These complexes may represent either a mechanism of organelle fusion or an abnormality of molecular organisation of the limiting unit membrane.

Cytoplasm↗
PubMed1979

An outbreak of disease in pigeons associated with a herpesvirus.

An outbreak of disease in young pigeons associated with a herpesvirus is reported. The clinical history, macroscopic and microscopic appearance of lesions and virus isolation are described. Most affected birds showed lesions in the upper alimentary tract epithelium as well as in skin, nasal mucosa and salivary glands. Lesions in liver, spleen and pancreas were uncommon. A herpesvirus capable of producing CPE on tissue culture and lesions on chorioallantoic membrane of developing chicken embryos was isolated and described. Inoculation of experimental pigeons with the virus failed to reproduce the disease.

Animals↗
PubMed1978

Schwann cell abnormalities in 2,5-hexanedione neuropathy.

Distinctive cytoplasmic alterations of Schwann cells were observed by electron microscopy in rats and mice with peripheral neuropathy induced by chronic exposure to 2,5-hexanedione. Pronounced enlargement of Schwann cells was due to accumulation of 100 angstrom cytoplasmic filaments and endoplasmic reticulum and was most often observed after 12--15 weeks exposure to 2,5-hexanedione. Examination of teased nerve fibres revealed segmental demyelination and remyelination involving axons of normal diameter as well as giant axons. The filament disorder induced by 2,5-hexanedione administration is not limited solely to axoplasmic contents. Possible mechanisms of demyelination are discussed and the changes are compared to those observed in human neuropathy for which 2,5-hexanedione appears to be the closest experimental model.

Animals↗
PubMed1978

Fragment of protein L18 from the Escherichia coli ribosome that contains the 5S RNA binding site.

A fragment of ribosomal protein L18 was prepared by limited trypsin digestion of a specific complex of L18 and 5S RNA. It was characterised for sequence and the very basic N-terminal region of the protein was found to be absent. No smaller resistant fragments were produced. 5S RNA binding experiments indicated that the basic N-terminal region, from amino acid residues 1 to 17, was not important for the L18-5S RNA association. Under milder trypsin digestion conditions three resistant fragments were produced from the free protein. The largest corresponded to that isolated from the complex. The smaller ones were trimmed slightly further at both N- and C-terminal ends. These smaller fragments did not reassociate with 5S RNA. It was concluded on the basis of the trypsin protection observations and the 5S RNA binding results that the region extending from residues 18 to 117 approximates to the minimum amount of protein required for a specific and stable protein-RNA interaction. The accessibility of the very basic N-terminal region of L18, in the L18-5S RNA complex, suggests that it may be involved, in some way, in the interaction of 5S RNA with 23S RNA.

Amino Acid Sequence↗
PubMed1977

Demyelination in allergic and Marek's disease virus induced neuritis. Comparative electron microscopic studies.

Patterns of demyelination were studied in sciatic nerves, spinal roots and ganglia of chickens afflicted with either Marek's disease (MD) or experimental allergic neuritis (EAN). MD was induced in susceptible chicks after hatching by inoculation of the JM strain of MD Herpes virus. Tissues from these chickens were examined 7-83 days after infection. EAN was studied 10-21 days after sensitization of 4 week old chickens to emulsions containing human peripheral nerve with complete Freund's adjuvant. In both conditions lesions were encountered which consisted of perivenular infiltrates of mononuclear cells that penetrated the basal lamina of the neurolemmal sheath, displaced Schwann cells, lysed and stripped myelin lamellae without damage to axons. Other lesions in MD were characterized by lymphomatous infiltrates that contained necrotic cells and disintegrating axons. The similarity of the demyelinating process in MD to that seen in EAN suggests that MD virus infection activates lymphocytes sensitized to peripheral nerve myelin. The findings are discussed with reference to acute idiopathic polyneuritis (Guillain-Barré syndrome) in patients with preceding or concurrent Herpes virus infections including those known to cause lymphoproliferative disorders.

Animals↗
PubMed1977

Ferritin immune complex deposits in the choroid plexus.

Mice injected intraperitoneally with 20 mg of ferritin twice weekly for more than 4 weeks developed proteinuria due to the deposition of ferritin-antiferritin antibody complexes in renal glomeruli. Deposits of ferritin, immunoglobulin G (IgG) and third complement component (C3) also accumulated in the perivascular, extracellular space of the choroid plexus as demonstrated by immunofluorescence and electron microscopy. The findings confirm previous observations on immune complex deposits in the choroid plexus in spontaneous autoimmune disease and persistent viral infections. The occurrence of similar deposits in the human choroid plexus and the possibility of an associated disturbance of the blood-spinal fluid barrier are discussed.

Animals↗