Biomedical subjects

A Martin

Publications and source records attributed to A Martin.

At least 451 records · Page 25Linked to original sources

PubMed1994

Epstein-Barr virus-associated primary malignant lymphomas of the pleural cavity occurring in longstanding pleural chronic inflammation.

Primary pleural non-Hodgkin's lymphomas (NHLs) have been described mostly in Japan and occasionally in western countries. We report three cases occurring in nonimmunocompromised patients demonstrating close similarities to the Japanese cases. These lymphomas occurred more than 20 years after thoracoplasty for the treatment of pleural or pulmonary tuberculosis. They were all high grade lymphomas of B phenotype (two immunoblastic with plasmocytoid differentiation and one immunoblastic with anaplastic large cells). In situ hybridization (ISH) detected small nuclear RNAs encoded by Epstein-Barr virus (EBERs) in most lymphomatous cells in all cases. This suggests a link between primary pleural lymphoma and the longstanding chronic inflammation, which could favor a clonal evolution of Epstein-Barr virus (EBV)-infected B cells through the production of growth factors or immunosuppressive cytokines produced by inflammatory cells.

Aged↗

PubMed1994

Cognition in Alzheimer's disease: disorders of attention and semantic knowledge.

Alzheimer's disease leads to a selective decline of cognitive skills, particularly semantic knowledge and visuospatial attention. Recent advances suggest that, although the two systems responsible for these skills can interact, the semantic memory deficit seen in Alzheimer's disease cannot be solely attributed to attention or retrieval deficiencies. This is consistent with a modular view of cognition, which postulates that disruption to these systems is selective in Alzheimer's disease. Cortico-cortical disconnection of association areas may disrupt widespread networks mediating attention and semantic knowledge in Alzheimer's disease.

Alzheimer Disease↗

PubMed1994

Aging and feature-specific priming of familiar and novel stimuli.

English and Turkish words in 2 fonts were presented to young and elderly Ss, and memory was assessed directly with recognition tests and indirectly with reading time. Young and elderly Ss showed repetition priming on English words and showed larger priming effects when the study and test fonts were the same rather than different. Elderly Ss were impaired, however, on recognition of feature-specific information in comparison with young Ss. When Turkish words were shown, only young Ss evidenced priming, despite recognition performance above chance for both young and elderly Ss. A 2nd experiment replicated these findings with different materials.

Adolescent↗

PubMed1994

Transgenic cereal (tritordeum) plants obtained at high efficiency by microprojectile bombardment of inflorescence tissue.

Transgenic cereal plants expressing the beta-glucuronidase (uidA) and neomycin phosphotransferase (neo) genes were obtained via microprojectile bombardment of immature inflorescence tissue of tritordeum (the fertile Hordeum x Triticum amphiploid, HchHchAABB). A total of 17 independent transgenic plants were recovered from 32 bombardments (on average four inflorescences per shot). Of the bombardment and culture parameters tested, explant preculture had the most influence on stable transformation frequency. The uidA and neo genes were supplied on two separate plasmids (co-transformation) and 88% of the transgenic plants recovered expressed both genes. Southern analysis confirmed the results of histochemical GUS and NPT II assays. Transgenic plants were grown to maturity and flowered and set seed. Pollen from four T0 GUS+ plants analysed showed GUS activity and T1 seedlings derived from one of the transgenic plants showed a segregation of 2.75:1 (GUS+:GUS-) for uidA gene activity.

Culture Techniques↗

PubMed1994

Working memory in individuals with HIV infection.

The central executive component (CE) of Baddeley's working memory model (Baddeley, 1992) was evaluated in 26 asymptomatic human immunodeficiency virus-infected individuals (HIV+) and 23 HIV-control subjects using a dual-task working memory paradigm. The HIV+ and HIV- groups showed an equivalent reduction in performance on both the primary task (visual vigilance) and the secondary task (letter span) when they were performed concurrently relative to when either task was performed alone. This result suggested normal CE functioning in these HIV+ subjects. In contrast, the HIV+ subjects had significantly longer response latencies on reaction time measures relative to the HIV- control group. These findings indicated that slowed processing in early stage HIV-infected individuals is not associated with a working memory deficit.

AIDS Dementia Complex↗

PubMed1994

Adrenocorticotrophin-induced hypertension in rats. Role of progesterone and digoxin-like substances.

Adrenocorticotrophin (ACTH) administration raises blood pressure in humans, sheep, and the rat. ACTH hypertension can be reproduced in sheep by combined infusion of aldosterone, 17 alpha-OH-progesterone, and 17 alpha,20 alpha-OH-progesterone, and in humans by cortisol. In the rat, ACTH hypertension is probably due to corticosterone. Progesterone treatment can prevent ACTH-induced hypertension in sheep. This study examined the ability of progesterone to antagonize the onset and development of ACTH-induced hypertension in Sprague-Dawley rats (n = 44). We also investigated the relationship of plasma digoxin-like substances (DLS) to ACTH hypertension. ACTH (0.5 mg/kg/day) significantly increased blood pressure (+24 +/- 5 mm Hg, P < .001) in association with an increase of water intake, urine output, and plasma sodium concentration, and a decrease of body weight and plasma potassium concentration. ACTH increased plasma DLS (+132 +/- 18 pg/mL, P < .01), and there was a positive correlation between DLS and blood pressure (r = 0.68, n = 22, P < .001). Progesterone (50 mg/kg/day) did not block the development of ACTH-induced hypertension in the rat. Although progesterone prevented the ACTH-induced rise in plasma sodium and glucose concentration, it did not prevent the decrease in plasma potassium concentration. The failure of progesterone to prevent ACTH-induced hypertension in the rat argues against a common "hypertensinogenic" mechanism for ACTH hypertension in sheep and rat. DLS may play a role in ACTH-induced hypertension in the rat.

Adrenocorticotropic Hormone↗

PubMed1994

Beta-carotene supplementation increases antioxidant capacity of plasma in older women.

The antioxidant effect of dietary beta-carotene supplementation on the peroxidation potential of plasma was investigated in a randomized double-blind, placebo-controlled study. Twelve healthy women (62-80 y) supplemented their usual daily diet with 90 mg of beta-carotene (n = 6) or placebo (n = 6) capsules for 3 wk. Plasma concentrations of beta-carotene, alpha- and gamma-tocopherol, ascorbate, urate, bilirubin and in vitro production of phosphatidylcholine hydroperoxides (PC-OOH) and utilization of plasma antioxidants in the presence of 50 mmol/L 2,2'-azobis (2-aminopropane) hydrochloride (AAPH), a free radical generator, at 37 degrees C were measured before and after dietary treatment. Plasma beta-carotene increased from 0.76 +/- 0.16 to 6.45 +/- 1.16 micromol/L (P < 0.05) in supplemented but not placebo-treated subjects. The plasma concentrations of other antioxidants did not change significantly in either group. beta-Carotene supplementation did not affect basal levels of plasma PC-OOH as measured by HPLC post-column chemiluminescence but did affect AAPH-induced production of PC-OOH. Before supplementation, the induction period of plasma PC-OOH production was 2.4 +/- 0.4 h, with levels reaching 5.39 +/- 1.50 micromol/L after 6 h of incubation. After supplementation, the induction period increased significantly to 4.2 +/- 0.4 h (P < 0.01), with a lower PC-OOH production of 2.16 +/- 0.90 micromol/L after 6 h (P < 0.05). In this system, plasma ascorbate concentrations were depleted first, followed by loss of bilirubin and alpha-tocopherol and then by the sequential loss of gamma-tocopherol, urate and beta-carotene. These results indicate that beta-carotene supplementation increases the plasma antioxidant capacity of older women.

Aged↗

PubMed1994

Metabolic myopathies.

Metabolic myopathies are disorders of muscle energy production that result in skeletal muscle dysfunction. Cardiac and systemic metabolic dysfunction may coexist. Symptoms are often intermittent and provoked by exercise or changes in supply of lipid and carbohydrate fuels. Specific disorders of lipid and carbohydrate metabolism in muscle are reviewed. Evaluation often requires provocative exercise testing. These tests may include ischemic forearm exercise, aerobic cycle exercise, and 31P magnetic resonance spectroscopy with exercise.

Carnitine↗

PubMed1994

T-cell receptor gene rearrangements in lymphoid and non-lymphoid leukaemias.

Rearrangements of delta-, tau-, and beta- T-cell receptor (TcR) chain genes were analysed in 64 haematologic malignancies comprising T- and B-lineage acute lymphoblastic leukaemias (ALL), B-chronic lymphocytic leukaemias (CLL), acute myeloid leukaemias (AML) and acute undifferentiated leukaemias AUL). The TcR genes were rearranged in 5/6 T-ALL. In non-T-leukaemias the frequency of TcR gene rearrangements was higher in B-lineage ALL (8/11), although they were all detected in B-CLL (5/29), AML (1/16) and AUL (2/4). Immunoglobulin (Ig) gene rearrangements were observed in 1/6 T-ALL and 2/14 AML. The analysis of these gene configurations has a diagnostic application since it allows the definition of the clonality of malignant proliferation and although they are not lineage specific such configurations represent a further parameter to evaluate, together with the immunophenotype and morphology, in the assignment or exclusion of the differentiation lineage of the haematologic malignancies.

Gene Rearrangement, T-Lymphocyte↗

PubMed1994

Cyclosporin hypertension in the Wistar rat: role of uninephrectomy.

1. The effects of cyclosporin A (CyA) solution (1-50 mg/kg per day), CyA powder (5-20 mg/kg per day) and vehicle, and the effects of renal mass reduction on CyA induced hypertension, were examined in conscious Wistar rats. 2. CyA solution consistently increased blood pressure at 5-20 mg/kg per day and the powder at 10-20 mg/kg per day. The vehicle had no consistent effect. 3. Both CyA solution and powder inhibited gain in bodyweight. There was no consistent effect on food intake, water intake or urine volume. Plasma sodium (Na+), and Na+ and potassium (K+) excretion were reduced by CyA 20 mg/kg per day. 4. Renal function was impaired by CyA powder at 20 mg/kg per day and plasma renin activity (PRA) was increased by all doses of CyA powder. 5. Thus, uninephrectomy did not potentiate CyA solution (5 mg/kg per day) induced increases in blood pressure and the effects of CyA do not appear to be a consequence of nephrotoxicity in Wistar rats.

Animals↗

PubMed1994

Predicting the solubility of drugs in solvent mixtures: multiple solubility maxima and the chameleonic effect.

An approach to reproduce the solubility profile of a drug in several solvent mixtures showing two solubility maxima is proposed in this work. The solubility of sulphamethoxypyridazine was determined at 25 degrees C in several mixtures of varying polarity (hexane:ethyl acetate, ethyl acetate:ethanol and ethanol:water). Sulphamethoxypyridazine was chosen as a model drug because of its proton-donor and proton-acceptor properties. A plot of the mole fraction of the drug vs the solubility parameter of the solvent mixtures shows two solubility peaks. The two peaks found for sulphamethoxypyridazine demonstrate the chameleonic effect as described by Hoy and suggest that the solute-solvent interaction does not vary uniformly from one mixture to another. The different behaviour of the drug in mixtures of two proton-donor and proton-acceptor solvents (alcohol and water), and in mixtures of one proton acceptor (ethyl acetate) and one proton donor-proton acceptor (ethanol) is rationalized in terms of differences in the proton donor-acceptor ability of the solvent mixtures. An approach based on the acidic and basic partial solubility parameters together with the Hildebrand solubility parameter of the solvent mixtures is developed to reproduce the experimental results quantitatively. The equation predicts the two solubility maxima as found experimentally, and the calculated values closely correspond to the experimental values through the range composition of the solvent mixtures. These results show that the chameleonic effect can be described in a quantitative way in terms of Lewis acid-base interactions; this approach can assist the product formulator to choose the proper solvent mixture for a new drug.

Acetates↗

PubMed1994

An unusual epithelial pleomorphic giant cell tumour of the pancreas with osteoclast-type cells.

A case of giant cell tumour of the pancreas with a mixture of pleomorphic giant cells and osteoclast-like cells is described. This association is rare and its histogenesis has been debated. The presence of a small differentiated adenocarcinomatous area at the periphery of the tumour indicates an epithelial origin. Moreover, some pleomorphic cells were positive for keratin (KL1). The osteoclast-like cells strongly expressed CD68 (a marker of histiomonocytic lineage) and did not show proliferative activity. They probably correspond to an unusual reaction of the stroma. Their clinical importance in this type of tumour remains unknown.

Antigens, CD↗

PubMed1994

Effect of experimental colitis on bone metabolism in the rat.

The influence of experimental colitis, induced by trinitrobenzenesulphonic acid with ethanol, on bone mineralisation and mineral metabolism was investigated in male rats. Three days after colitis induction, there was a significant rise (p < 0.01) in urinary calcium excretion, which was still present 20 days later (p < 0.05). Three weeks after colitis induction, urinary hydroxyproline excretion was significantly increased (p < 0.01), while urinary cyclic AMP and phosphorus decreased. Colitis was associated with reduced bone density (p < 0.025), ash weight (p < 0.05) and calcium/volume ratio (p < 0.05), whereas no change was found for bone volume and the phosphorus/volume and magnesium/volume ratios. Serum minerals remained unchanged. We conclude that chronic experimental colitis in the rat leads to resorptive hypercalciuria, increased urinary hydroxyproline and osteopenia. Considering site of inflammation, diet, sex, and absence of therapy, inflammatory mediators, e.g. cytokines, with known catabolic effects on bone, might be involved in the pathogenesis of osteopenia.

Animals↗

PubMed1994

Dose-response characteristics of galactose-induced cataract in the rat.

The onset and progression of cataract was investigated in weanling Sprague-Dawley rats fed 10, 15, 20 and 30% dietary galactose (groups 1-4) for 45-226 days. Cataracts were graded on a 0-5 scale. After 226 days, 9% of the rats fed 10% galactose developed lesions beyond the very early stage of cataractogenesis (grade 1). After 154 days 50% of the rats fed 15% galactose developed subcortical cataract (grade 3) with no nuclear cataract. In the rats fed 20% galactose, an initial rapid development by 31 days of a grade 3 cataract was observed in 50% of the eyes. Advancement to grade 4 and grade 5 cataract proceeded more slowly; by 207 days, 45% of the eyes had grade 5 cataract. In rats fed 30% galactose, rapid vacuolization and development of nuclear cataracts (grade 5) were observed by day 44. Dietary galactose at levels of 20 and 30% was associated with a significant reduction in weight gain at the early stage of dietary treatment. These observations demonstrate that 10-30% dietary galactose induces cataract in rat lens in a dose- and time-dependent fashion. These data serve to further establish this animal model as a useful model for studying the sequelae of cataractogenesis.

Animals↗

PubMed1994

Lupus autoantibodies to native DNA cross-react with the A and D SnRNP polypeptides.

Antibodies to native DNA (nDNA) in sera from patients with systemic lupus erythematosus have been found to frequently correlate with antibodies to the A and D SnRNP proteins measured in Western blot assays. 40 of 54 SLE (74.1%) sera with anti-nDNA bound to A and D proteins, while 9 of 113 sera (8%) without anti-nDNA bound the A and D proteins, P < 10(-8) by Fisher's exact test. Antibodies to nDNA correlated closely with anti-A and anti-D in seven of eight patients followed sequentially, r = 0.7865. Nine human polyclonal anti-nDNA populations were isolated from DNA cellulose columns. Seven reacted equally with A and D, and two reacted predominantly with D. Two of three murine monoclonal anti-DNA antibodies isolated from NZB/NZW F1 hybrid mice bound A and D equally in Western blot with a titer > 1/40,000. These reactions were directed to the unfolded A and D proteins measurable in Western blot since these monoclonals (and several of the human anti-nDNA populations) failed to react with native U1RNP in ELISA or in RNA immunoprecipitation experiments. These newly recognized cross reactions of anti-nDNA may amplify the immune response to DNA and be part of the original immunogenic drive.

Animals↗

PubMed1994

Fieldwork education: a shared supervision model.

This paper describes how McMaster University, Department of Occupational Therapy implemented a shared supervision model during an adult physical health block clinical placement, in two fieldwork settings in Hamilton. Five students were assigned to each of the clinical facilities and spent time with the group supervisors and clinical preceptors to meet their learning needs. The objectives, implementation process, training and orientation process, learning and evaluation process, and outcome of this project are discussed. The shared supervision model appears to be a viable alternative supervision model in fieldwork education.

Clinical Clerkship↗

PubMed1994

Maintaining a balance in service and education in a climate of fiscal crisis.

Doubling enrollment in the undergraduate occupational therapy programme at McMaster University was introduced in a climate of fiscal crisis. This paper will discuss the creative implementation of a Quality Circle Model in the Occupational Therapy Department at Chedoke-McMaster Hospitals, Hamilton, Ontario, which promoted concerted staff participation and self management development in light of increased student learning needs. An alternate model of Clinical Supervision was examined. The impact of this proactive, problem solving approach will be addressed and may encourage application in other occupational therapy settings.

Financial Management, Hospital↗

PubMed1994

Creatinine metabolism impairment by an anticonvulsant drug, phenacemide.

OBJECTIVE: To report two cases of increased true serum creatinine (Scr) without renal failure caused by an anticonvulsant drug, phenacemide, and to discuss the possible mechanisms. CASE SUMMARY: Two patients treated with phenacemide were investigated for markedly increased Scr and decreased creatinine clearance (Clcr) values. Glomerular filtration rates, as determined by 125I-iothalamate clearance, were normal in both patients and analytical interferences with the Jaffé reaction were excluded. After discontinuation of the drug, phenacemide concentrations became undetectable within 2 days but it took 7-14 days for Scr and Clcr to return to normal values. DISCUSSION: The Scr increase with phenacemide (120-170 percent) was higher than that reported with cimetidine or trimethoprim (10-40 percent) and could not be explained solely by inhibition of the tubular secretion of creatinine. The hypothesis of an overproduction of creatinine caused by phenacemide was ruled out by experimental studies in rats. Creatinine increase in tissues was lower than that in the serum of rats given phenacemide. In vitro creatinine influx into red blood cells was inhibited in a dose-dependent way by phenacemide. CONCLUSIONS: Increased Scr concentrations in these patients could be related to an inhibition of transport and a decrease in creatinine volume of distribution. Creatinine concentrations should not be considered when dosage adjustments of renally eliminated drugs are being calculated for patients with such metabolic interferences.

Adult↗