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Biomedical subjects

M F Ryan

Publications and source records attributed to M F Ryan.

At least 19 recordsLinked to original sources
PubMed1998

An immunohistochemical investigation of the adult stage of the equine parasite Strongylus vulgaris.

Adult Strongylus vulgaris, collected from the caecum of infected horses and embedded in paraplast using standard methods, were sectioned for immunohistochemistry (IHC) studies. Antibodies were raised in rabbit against the excretory-secretory product (ESP) and against two constituent protein bands (28-30 kDa). The use of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), enzyme-linked immunosorbent assay (ELISA) and immunoblotting indicated the immunogenicity of ESP and of the subunits (28-30 kDa). In ELISA, both rabbit hyperimmune sera recognized the ESP and (28-30 kDa) bands consistently and strongly. Both hyperimmune sera recognized most ESP subunits (80, 60, 54, 42, 35, 30, 20 and 15 kDa) in immunoblots. IHC, using light microscopy, suggested that the following worm tissues reacted strongly and positively with both antisera: amphids, tooth core, intestine, excretory gland and ducts, and hypodermis. Thus, either these are antigen-producing tissues, or antigens sharing common epitopes occur in them. The following tissues reacted weakly: body cuticle, buccal capsule cuticle, oesophagus, and also somatic muscle (non-contractile portion) perhaps due to diffusion of antigen from adjacent tissues. Preimmune serum gave a negative reaction with most worm tissues.

Animals↗
PubMed1997

Enzymatic properties of the Duvernoy's secretion of Blanding's tree snake (Boiga blandingi) and of the mangrove snake (Boiga dendrophila).

Duvernoy's secretion from representatives of the colubrid genus Boiga has been shown by other workers: (1) to contain an alpha-bungarotoxin-like component (Blanding's tree snake, Boiga blandingi); (2) to exhibit acetylcholine receptor binding activity (the brown tree snake, Boiga irregularis); and (3) to react strongly (B. blandingi and the mangrove snake, Boiga dendrophila) with antisera raised against elapid venoms. The present study provides the first evidence for the presence of acetylcholinesterase, a common elapid enzyme, in the Duvernoy's secretion of B. dendrophila and B. blandingi at levels of 122 +/- 7 and 0.36 +/- 0.02 International Enzyme Units, respectively. Constants for inhibition by eserine were 1.25 x 10(-7) M and 2.79 x 10(-7) M, respectively. The Duvernoy's secretion of B. dendrophila exhibited significant phospholipase and haemolytic activities, whereas phosphodiesterase was only weakly present and no thrombin-like activity was observed.

Acetylcholinesterase↗
PubMed1996

Growth and adrenal suppression in asthmatic children treated with high-dose fluticasone propionate.

BACKGROUND: Fluticasone propionate was introduced in 1993 in the UK as a potentially safer inhaled corticosteroid than those already in use. The efficacy and safety of fluticasone has been established at recommended doses of 200 micrograms/day, but not at higher doses that are often used. METHODS: Growth retardation was observed in six severely asthmatic children after introduction of high-dose fluticasone propionate treatment (dry powder). Assessment of cortisol response was by insulin-induced hypoglycaemia in three cases, by short tetracosactrin test in two, and by low-dose tetracosactrin and 24-hour urinary cortisol/creatinine ratio in one. FINDINGS: Six children with growth retardation noted after treatment with high-dose fluticasone propionate were found to have adrenal suppression. In one case the growth rate and cortisol response returned to normal 9 months after the fluticasone dose was reduced to 500 micrograms/day. INTERPRETATION: When high doses of fluticasone propionate are used, growth may be retarded and adrenal suppression may occur.

Administration, Topical↗
PubMed1996

Evidence for a correlation between ambient cholesterol levels and soluble plasma sialyltransferase enzyme activity.

While soluble forms of the sialyltransferase (sialyl-T) enzyme have been detected in significant quantities in serum, the exact source(s) of the enzyme, or the factors controlling its secretion are poorly understood. In this study, we have examined the relationship between ambient plasma cholesterol concentrations and sialyl-T-activities and also levels of constituent plasma sialoglycoproteins (SGP). There was an inverse relationship between levels of the alpha 2, 6 sialyl-T enzyme and both total plasma cholesterol and HDL, although no such relationship was observed for the alpha 2,3 enzyme. While there was no correlation between total cholesterol and the levels of plasma SGPs, there was an inverse relationship between the HDL component and alpha 2,3 SGPs.

Cholesterol↗
PubMed1995

Peripheral transluminal angioplasty under ultrasound guidance: initial clinical experience and prevalence of lower limb lesions amenable to ultrasound-guided angioplasty.

PURPOSE: Currently, endovascular techniques require monitoring by radiographic imaging for accurate catheter placement. The aim of this study was first to determine the feasibility of angioplasty under ultrasound guidance using a special catheter system. Based on this outcome, the second goal was to investigate the prevalence of lesions amenable to ultrasound-guided angioplasty. METHODS: A balloon catheter system (Echomark) has been developed, which allows accurate catheter guidance by ultrasound imaging. An ultrasound-sensitive piezoelectric sensor positioned in the middle of the balloon portion of the angioplasty catheter is interfaced to an external duplex scanner via the catheter system. The exact position of the balloon relative to the transducer is calculated and reproduced on the screen of the duplex scanner to guide balloon positioning. In the feasibility assessment of the procedure, 16 patients with disabling claudication and rest pain were selected for balloon angioplasty under ultrasound guidance based on arteriographic and hemodynamic lesion criteria of > 50% stenosis with a peak systolic velocity ration > 2.5 in a lesion < 4 cm long that could be imaged by duplex ultrasonography. A fall in the peak systolic velocity ratio below 2.0 was selected for a procedural endpoint corresponding to < 30% residual stenosis on the completion angiogram. In the second part of the study, the prevalence of stenoses amenable to ultrasound-guided angioplasty was studied in 80 patients presenting with symptoms of peripheral arterial disease. RESULTS: In the feasibility study, 20 stenoses (5 common iliac, 6 external iliac, and 8 superficial femoral arteries and 1 graft) meeting the inclusion criteria were subjected to ultrasound-guided angioplasty with confirmation by completion angiography. The procedure was possible in 18 (90%) of the 20 stenoses. The two failures occurred in iliac arteries that could not be imaged by duplex scanning due to obesity, bowel gas, and/or vessel wall calcification. In one case, the peak systolic velocity ratio exceeded 2.5 despite a satisfactory control arteriogram; redilation was performed, and the ratio fell below 2.0. In the second part of the study, 21 (26.2%) of the 80 patients had 29 stenoses that were amenable to angioplasty according to angiographic criteria (> 50% stenosis and < 4 cm length). All these stenoses were evaluated with duplex scanning to determine their suitability for angioplasty under ultrasound guidance. Twenty-three (79%) of the 29 lesions selected for angioplasty were well visualized by duplex, and angioplasty would have been possible based on our initial clinical experience. CONCLUSIONS: Angioplasty under ultrasound control is a feasible technique for peripheral lesions. Ultrasound allows monitoring of both anatomical and hemodynamic parameters during angioplasty and thus provides a procedural endpoint that correlates to the control angiogram. A large proportion (79%) of stenoses deemed suitable for angioplasty can be well visualized by ultrasound, but obesity, vessel wall calcification, and bowel gas may limit the ability to obtain a satisfactory ultrasound image. Ultrasound-guided angioplasty is a potentially useful procedure that warrants further investigation.

Angioplasty, Balloon↗
PubMed1994

Characterisation of proteolytic activity of excretory-secretory products from adult Strongylus vulgaris.

An excretory-secretory (ES) preparation derived from adult Strongylus vulgaris in vitro was assessed for proteolytic activity using azocasein and synthetic, fluorogenic, peptide substrates. Fractionation was by molecular sieve fast protein liquid chromatography (molecular sieve FPLC) and resolution by gelatin-substrate sodium dodecyl sulphate-polyacrylamide gel electrophoresis (gelatin-substrate SDS-PAGE). The cysteine proteinase activator, dithiothreitol (DTT), enhanced azocaseinolysis and hydrolysis of carbobenzoxy-phenylalanyl-arginine-7-amido-4-methylcoumarin (Z-Phe-Arg-NMec) by the ES preparation and was a requirement for the detection of carbobenzoxy-arginyl-arginine-7-amido-4-methylcoumarin (Z-Arg-Arg-NMec) hydrolysis. Assays of FPLC-eluted fractions, with DTT, detected a broad peak of azocaseinolytic activity (22-24 kDa) and two peaks (24 and 18 kDa) of hydrolysis using the synthetic substrates. Hydrolysis by these peaks of Z-Phe-Arg-NMec was 50-fold greater than that of Z-Arg-Arg-NMec suggesting that their specificities are more like papain or cathepsin L rather than cathepsin B. In gelatin-substrate SDS-PAGE, DTT was required to detect proteolysis by the ES preparation which was optimal at pH 6.0 and resolved into eight bands (87-29 kDa). Cysteine proteinase inhibitors were the most effective in all assays. Collectively, these data indicate that cysteine-class proteolytic activity predominates in the ES preparation of adult S. vulgaris.

Animals↗
PubMed1993

Haemopoietic regrowth after chemotherapy for acute leukaemia: an immunohistochemical study of bone marrow trephine biopsy specimens.

AIM: To analyse haemopoietic regrowth and residual disease in bone marrow trephine biopsy specimens after treatment for acute leukaemia, using immunohistochemical staining. METHODS: Biopsy specimens before and after treatment were studied from patients diagnosed as having acute myeloid or lymphoblastic leukaemia. Specimens after treatment encompassed periods from two to 56 weeks from the start of treatment. Routine haematoxylin and eosin and Giemsa stained sections were evaluated in association with immunostained preparations. A panel of antibodies was used, which reacts with epitopes showing restricted expression dependent on the lineage or maturation stage of cells. Results were evaluated in the light of clinical, peripheral blood, and marrow aspirate findings. RESULTS: The speed and sequence of regrowth of haemopoietic cells were more variable than expected. Immunostaining highlighted features of dysplasia after treatment and in some cases assisted detection of residual or relapsed leukaemia. Peripheral blood and aspirate cell counts reflected accurately the amount of regrowth, but not the dysplasia, seen in biopsy samples. Delayed regrowth was associated with complex individual factors. CONCLUSIONS: Morphological and immunohistochemical study of trephine biopsy specimens from patients treated for acute leukaemia provides information complementary to that obtained from peripheral blood and aspirated marrow. Variation in the timing and sequence of regrowth is highlighted. Immunostaining can aid in the detection of relapse or minimal residual leukaemia. The clinical relevance of dysplastic changes in biopsy specimens after treatment is uncertain, but such changes may persist for long periods.

Acute Disease↗
PubMed1992

Clinical evaluation of a rapid parathyroid hormone assay.

Modifications to the incubation conditions of radioimmunoradiometric assay for whole molecule parathyroid hormone (PTH) permit accurate quantification of the hormone in the peripheral circulation within 1 h of sampling. We assessed the assay intraoperatively in 75 patients undergoing parathyroidectomy. Serum PTH concentration declined to less than 20% of its pre-operative value within 20 min of the successful completion of surgery provided that renal function was normal. In patients with chronic renal failure the rate of decline in serum PTH concentration after parathyroidectomy was slower in some cases. In four cases of unsuccessful parathyroidectomy, serum PTH concentration remained above 60% of its preoperative value. Intraoperative monitoring during parathyroidectomy using this rapid PTH assay offers considerable advantages to the surgeon over frozen section.

Adult↗
PubMed1991

The role of magnesium in clinical biochemistry: an overview.

Magnesium is the second most abundant intracellular cation. It is essential for a wide variety of metabolically important reactions, in particular those involving ATP. Hypomagnesaemia is surprisingly common in hospital populations but is sometimes either undetected or overlooked. Serum magnesium concentrations provide a guide to magnesium status but while hypomagnesaemia is a reliable indicator of magnesium deficiency, normomagnesaemia does not exclude magnesium depletion. A wide variety of conditions predispose to magnesium depletion. Clinical magnesium deficiency has potentially fatal consequences in vulnerable groups of patients and should be excluded in all such cases. Magnesium deficiency may result in hypokalaemia, hypocalcaemia or other disturbances of electrolyte homeostasis, refractory cardiac arrhythmias, or increased sensitivity to digoxin. The capacity to measure serum and urine magnesium concentrations rapidly, regularly and reliably should be part of the repertoire of all clinical chemistry laboratories involved in the care of critically ill patients.

Homeostasis↗
PubMed1990

Modification to a commercial immunoradiometric assay permitting intraoperative monitoring of parathyroid hormone levels.

We describe a modification to a commercially available immunoradiometric assay which reduces the turnaround time for parathyroid hormone (PTH) measurement to 1 h and permits intraoperative monitoring during parathyroidectomy. Alterations in PTH concentrations following removal of parathyroid tissue are compared with those of calcium, ionised calcium and phosphate. PTH measurements obtained intraoperatively permit definitive conclusions about the success of the operation within 1 h of sampling, allowing re-exploitation of the gland to take place immediately if necessary.

Calcium↗
PubMed1989

Serum hypomagnesaemia in an elderly day-hospital population.

Serum magnesium concentration was measured in 223 elderly patients attending a day-hospital. Patients with medical conditions or receiving medication (other than digoxin/diuretics) which could affect magnesium levels were strictly excluded from the study. All patients were living in the community and were medically stable. Ninety-five patients were on no therapy whilst 107 were on diuretic therapy. In spite of strict exclusion criteria, 10.3% of patients on no therapy had serum magnesium levels below normal. There were 61 patients receiving a combination of frusemide and amiloride and 11.9% of these patients had below normal levels of serum magnesium. We conclude that there is a significant prevalence of unexpected hypomagnesaemia among Dublin inner city day hospital elderly patients. Significant serum hypomagnesaemia may still occur in patients on potassium/magnesium sparing diuretics.

Aged↗