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Biomedical subjects

J R O'Donnell

Publications and source records attributed to J R O'Donnell.

At least 19 recordsLinked to original sources
PubMed2006

Myelodysplastic patients with raised percentage of hypochromic red cells have evidence of functional iron deficiency.

Raised percentage hypochromic red cells (%HRC) were detected at diagnosis in 10 of 34 consecutive patients with low-risk myelodysplastic syndrome (MDS) [refractory anemia (RA) (4/26) and RA with ring sideroblasts (6/8)], all of whom had normal or increased serum ferritin and bone marrow iron stores. Elevated %HRC has persisted in all 10 cases and subsequently developed in another RA patient who later had a complete remission of MDS with normalisation of %HRC after a respiratory tract infection. A strong positive correlation was found between %HRC and erythrocyte zinc protoporphyrin levels in 11 MDS patients tested (p=0.01), suggesting that functional iron deficiency contributes to ineffective erythropoiesis in cases of MDS with raised %HRC. Five of seven patients with elevated %HRC had satisfactory haemoglobin responses to a trial of human recombinant erythropoietin without iron supplementation.

Anemia, Hypochromic↗
PubMed2000

The impact of aspirin therapy and anticoagulation on the prevalence of spontaneous subdural haematoma.

A retrospective analysis was performed of all patients who received operative intervention for subdural haematoma at the Beaumont neurosurgical unit between 1994 and 1997 inclusive. There were 123 spontaneous (mean age 74 +/- 5 years) and 77 traumatic haematomas (mean age 43 +/- 23 years) in the series. Ninety three patients (76%) in the spontaneous group were on antiplatelet agents or anticoagulants (78 aspirin, 15 warfarin) and the indication for their use was unknown in twenty four patients (19%). The re-operation rate in the group on aspirin and anticoagulants was twice that in the non aspirin / non anticoagulant group. These results highlight a significant medical problem and emphasise the need for cautious use of antiplatelet and anticoagulant agents, particularly in the elderly.

Adult↗
PubMed1997

Haematological reference ranges for schoolchildren.

There are few reports of reference ranges for haematological values in school age children and most studies extend over a small age range or have excluded a considerable proportion of the study population in an effort to omit those with haemoglobinopathies or anaemia. Blood samples from 2135 children aged 4-19 years, from randomly selected schools, were analysed by automated counter. Reference ranges for red cell, white cell and platelet indices are provided from the results. Median haemoglobin and red blood cell count values for girls and boys rose together with increasing age, up to 12 years, but then diverged. Girls had a higher platelet count than boys. Mean platelet volume rose with age and was inversely related to the platelet count. Plateletcrit fell with age but in girls there was a peri-pubertal peak. Total leucocyte count fell with age. The upper limits for total leucocyte count in this study are approximately 2 x 10(9) lower than those quoted in modern haematology textbooks. Lymphocyte, eosinophil and basophil counts fell with age with little difference between the sexes. Neutrophil and monocyte counts were similar for younger girls and boys but diverged in the older children with the older girls having higher values than boys.

Adolescent↗
PubMed1995

Characterization of the defects in murine peritoneal macrophage function in the early postsplenectomy period.

Postsplenectomy bacterial sepsis may be fatal, due to defects in both cellular and humoral immune responses. The objective of this study was to assess the efficacy of peritoneal macrophage antibacterial function in the early postsplenectomy period. Murine models of splenectomy and sham operation were characterized and peritoneal macrophages were harvested 24 h to 1 wk after surgery. Cells from splenectomized animals demonstrated a nonsignificant delay in phagocytosis of Escherichia coli at 24 h with, however, significantly impaired killing of intracellular organisms at 24 h and 1 wk compared to the sham group. Paradoxically, the production of the macrophage antibacterial product superoxide anion was not impaired at either time point in the splenectomy group compared with sham-operated and control mice. Nitric oxide release was significantly lower in the splenectomized group (p = 0.006), a possible explanation for reduced bacterial killing. Mortality from bacterial peritonitis was significantly higher with concomitant splenectomy than in the sham splenectomy group at 24 h (p < 0.02). The production of TNF from macrophages was up-regulated immediately following splenectomy, a cytokine which may contribute to mortality from bacteremic shock. Local defects in macrophage antimicrobial function may contribute significantly to bacteremia and to subsequent mortality in the early postsplenectomy period.

Animals↗
PubMed1993

Splenectomy predisposes to fungal sepsis through defective phagosome formation.

Postsplenectomy septic sequelae may be fatal, but the mechanisms are unclear. We hypothesized that peritoneal macrophage (PM phi) antimicrobial function is abnormal following splenectomy and that this may predispose to increased mortality from the fungal pathogen Candida albicans. Study 1 (in vivo): female CD-1 mice were randomized into control (C), laparotomy (L), or laparotomy+splenectomy (L + S) and inoculated with C. albicans (10(7) organisms, ip) and were studied for mortality. Study 2 (in vitro): mice were randomized to C, L, or L + S groups. Twenty-four hours later, PM phi were harvested and studied for their antifungal activity, including percentage PM phi ingestion of C. albicans and vacuolar sealing of C. albicans within PM phi, percentage C. albicans killing, and superoxide anion (O2-) generation, the mechanism by which candida are killed. Results showed decreased phagocytosis and killing of C. albicans in the L + S group (P < 0.05 vs C) and reduced vacuolar sealing (P < 0.05 vs C) but significantly higher O2- release compared to that in other groups (P < 0.05). Mortality in the L + S group from C. albicans sepsis was significantly higher than that in the other groups (60% compared to 20% in the L group and 13% in C, P < 0.02). This may have resulted from L + S-induced defective phagocytosis of C. albicans and depressed C. albicans killing but increased O2- release in response to candida. This discrepancy between decreased killing and increased O2- may result from increased leakage of O2- from more unsealed vacuoles in the L + S group. Thus, L + S may predispose to candida-induced mortality through defective PM phi intracellular candida killing while enhancing the release of O2- extracellularly from unsealed vacuoles, causing tissue injury.

Animals↗
PubMed1989

Bronchial responsiveness and inflammation in guinea pigs exposed to acrolein.

Bronchial hyperresponsiveness can be produced experimentally after inhalation of numerous nonimmunospecific stimuli; our objective was to determine whether acrolein, a component of cigarette smoke, could increase bronchial reactivity to intravenously administered acetylcholine in guinea pigs. Bronchial responsiveness was assessed twice before and 1, 2, 6, and 24 h after exposures to less than or equal to 0.01 (sham), 0.31, 0.67, 0.94, or 1.26 parts per million for 2 h (5-7 guinea pigs/group). To examine the possible relationships of responsiveness to inflammatory mediator release and cellular infiltration, bronchoalveolar lavage was performed in another 30 guinea pigs before (control) and 0, 1, 2, 6, or 24 h after exposures. Pulmonary resistance was increased immediately after exposure (5 min) and returned to control values within 30-60 min. Increased bronchial responsiveness was evident within 1 h and became maximal 2-4 h after exposure. The acetylcholine dose necessary to double resistance decreased from 104.2 +/- 7.3 to 79.6 +/- 15.9 at 1 h and was 32.5 +/- 7.9 at 2 h and 32.8 +/- 7.6 micrograms.kg-1 at 6 h. Increases in two eicosanoids, thromboxane B2 (from 167 +/- 21 to 314 +/- 77 pg/ml) and prostaglandin F2 alpha (from 98 +/- 20 to 285 +/- 62 pg/ml) occurred immediately after exposure, whereas an influx of neutrophils occurred 24 h later (from 2.2 +/- 1.2 to 11.3 +/- 3.6%). These temporal relationships suggest that neutrophil infiltration may be a sufficient but not a necessary condition for the onset of bronchial hyperresponsiveness and that injury to cells normally present in the lung are responsible for the mediators thought to influence bronchial responsiveness.

Acetylcholine↗
PubMed1987

Control of oral anticoagulant treatment by chromogenic prothrombin assay.

Doses of oral anticoagulants in 50 patients on long term treatment were easily and satisfactorily monitored over six months by an automated chromogenic assay of prothrombin (CPA). It is suggested that chromogenic assay of one or more of the vitamin K dependent coagulation factors would provide a readily standardised alternative to those conventional tests which depend on human brain derived reagents, now regarded as a biohazard.

Administration, Oral↗
PubMed1985

The potential value of immuno-isoelectric focusing in the diagnosis and management of solitary plasmacytoma.

Immuno-isoelectric focusing is a highly sensitive method of detecting small quantities of monoclonal protein. We have previously reported the first demonstration of serum paraprotein in non-secretory myeloma using this technique (Sheehan et al. 1985). We now report a case of solitary plasmacytoma where this technique revealed a small concentration of serum paraprotein when conventional techniques failed, and discuss the potential value of focusing in plasma cell dyscrasia, with limited tumor cell mass. focusing in plasma cell dyscrasia, with limited tumour cell mass.

Aged↗