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Biomedical subjects

D Abramson

Publications and source records attributed to D Abramson.

At least 19 recordsLinked to original sources
PubMed2002

Comparison of Canadian Fusarium graminearum isolates for aggressiveness, vegetative compatibility, and production of ergosterol and mycotoxins.

Fusarium graminearum is the predominant pathogen causing fusarium head blight of cereals in North America. Fifteen Canadian isolates of Fusarium graminearum were highly diverse in terms of vegetative compatibility grouping (VCG) and varied for production of ergosterol and mycotoxin production in rice culture. Aggressiveness was assessed by scoring the disease severity incited in wheat spikes by each isolate. Two inoculation methods, single-floret injection and spray of entire spikes, were used to screen 4 wheat varieties for reaction to the F. graminearum isolates. All isolates were of broadly similar aggressiveness, with disease severity ranging from 17.2 to 39.1 for single floret injection, and 39.1 to 69.0 for spray inoculation. Disease severity, ergosterol production, and mycotoxin development were not correlated. Using nitrate non-utilizing mutants the 15 isolates were grouped into 14 VCGs. Deoxynivalenol (DON) was produced by all isolates in rice culture, at levels between 0.2 and 249 ppm. 15-acetyldeoxynivalenol was produced by 14 of the 15 isolates at levels between 0.4 and 44.6 ppm. These results reveal a high level of diversity for several characteristics among F. graminearum isolates from Canada.

Culture Media↗
PubMed2002

Moniliformin in barley inoculated with Fusarium avenaceum.

To assess production of the mycotoxin moniliformin, inoculation trials with four barley cultivars and local isolates of Fusarium avenaceum were performed at two different experimental farms in southern Manitoba, Canada, during 1997-99. In the 1997 study, moniliformin was detected in 11 of 16 barley rows at levels between 0.19 and 1.62 mg g(-1), and F. avenaceum infection ranged from 10 to 57% in rows where the toxin was detected. In the 1998 study, moniliformin was detected in only three of 16 barley rows, with levels between 0.06 and 0.43 micro g g(-1), and F. avenaceum infection between 16 and 39%. In the 1999 study, moniliformin was detected in 11 of 16 barley rows with levels between 0.09 and 0.42 micro g g(-1), and F. avenaceum infection between 37 and 76%. In the 1997 trial, moniliformin was found in a single water-inoculated control row at 0.15 micro g g(-1). The data suggest that in years of high rainfall and F. avenaceum infection, moniliformin is likely to be found in Manitoba barley.

Cyclobutanes↗
PubMed2001

The development of young children with retinoblastoma.

OBJECTIVES: To assess the health and development of children with retinoblastoma (RB), or cancer of the retina, and to determine if they are at greater risk for developmental delays than normal children. Specific aims were to determine if type of RB (unilateral vs bilateral), family history, and number of treatment types affected mental and motor development. DESIGN: Descriptive study based on medical record review and pediatric, psychological, and visual evaluations. SETTING: Major referral center for patients with RB and early intervention program in a voluntary urban hospital. SUBJECTS AND METHODS: Fifty-four children younger than 41 months with RB who attend an ophthalmology oncology clinic were recruited for study. Measures included demographic variables such as social class and race/ethnicity, and medical factors such as age at diagnosis (<18 months vs >18 months), type of RB (unilateral or bilateral), family history of RB, and number and types of treatments. All children received a pediatric examination that assessed physical growth and health; a behavioral test of visual acuity using Teller acuity cards; and the Bayley Scales of Infant Development II, a standardized test of mental and motor development. Children found to have delays were referred to intervention services to treat their specific areas of weakness. RESULTS: Three quarters of the children had had 1 eye enucleated; 51 of 54 had normal vision in at least 1 eye, and the other 3 had partial vision in 1 eye. Except for the RB, 46 children were largely normal in growth and health, and 8 had medical diagnoses that were unrelated to RB or its treatment. The average mental and motor development scores were in the normal range (91.4 +/- 16.3, and 91.1 +/- 13.4) and not significantly lower than the normal population. Twenty-six children were referred for early intervention services, and 21 of 26 were referred for services to improve their visuomotor coordination. Demographic variables were not associated with medical variables or outcome. Children with bilateral RB, in which both eyes are affected, performed significantly less well in motor development, received many more types of treatments, and were more likely to be referred for visuomotor therapy than children with unilateral RB. CONCLUSIONS: Children with RB generally function normally in terms of physical health and mental and motor development. However, they are more likely to show delays in visuomotor integration. Early developmental evaluations may improve the visuomotor development of children with visual impairment due to RB.

Analysis of Variance↗
PubMed2001

Safe storage time of high moisture wheat.

Deterioration rates were determined for 15-19% moisture content (m.c., wet basis) wheat (Triticum aestivum L. cv. 'Barrie') stored at constant temperatures or with a step decrease in storage temperatures. Deterioration rates were determined by measuring germination capacity of the grain and respiration rates of grain and microorganisms. Safe storage time was defined as the time for germination to decrease to 90%. Safe storage times of 19% m.c. wheat stored at constant temperatures ranged from 2.5 d at 30 and 35 degrees C to 37 d at 10 degrees C. Deterioration rates of 19% m.c. wheat stored with a step decrease in storage temperatures (35-25, 30-20, 25-20, and 20-15 degrees C) were determined and safe storage times were satisfactorily predicted. Safe storage times of 17% m.c. wheat were 5, 7, and 15 d at 35, 30, and 25 degrees C, respectively. Respiration rates and germination percentages of 15 and 16% m.c. wheat stored at 25 degrees C remained constant for 70 d. The respiration rates of 17-19% m.c. wheat at 25 degrees C increased while the germination percentages decreased with storage time. Germination dropped from 98 to 92-89% when the dry matter losses were about 0.05% and visible mould occurred when the dry matter losses were about 0.1% in 17-19% m.c. wheat. Safe storage times of 17% m.c. wheat stored at 35-25 degrees C were compared with those determined in similar previous work with cultivars 'Domain' and 'Katepwa'. 'Domain' had the longest and 'Barrie' had the shortest storage times.

Journal Article↗
PubMed2001

Alterations of cell cycle regulators affecting the RB pathway in nonfamilial retinoblastoma.

We undertook the present study to examine alterations affecting the RB pathway in the G1 checkpoint and to determine their potential clinical significance in children affected with nonfamilial retinoblastoma. Using immunohistochemistry, patterns of expression of pRB, p16/INK4A, and E2F1 were analyzed in tissue from a cohort of 86 well-characterized patients with nonfamilial retinoblastoma diagnosed at the "Instituto Nacional de Pediatria" in Mexico City. The relationship of these phenotypes to proliferative index was assessed by analysis of Ki67 antigen expression. pRB expression was found in 11 (13%) cases. Using a hypophosphorylated specific pRB antibody, we observed low levels of underphosphorylated pRB expression in only 1 of 9 evaluable positive cases. These data suggest that the detected pRB products were hyperphosphorylated and thus had decreased functional activity. Increased p16 nuclear expression was found in only 6 tumors. No tumors showed deletions or mobility shifts of the INK4A gene. Undetectable pRB levels were significantly associated with undetectable p16 expression (odds ratio, 10.8; 95% confidence interval, 1.4-81.3; P =.03). All tumors showed nuclear immunoreactivities for E2F1 and Ki67. Increased Ki67 proliferative index was associated with increased staining for E2F1 (r =.44; P =.008) and increasing clinical stage (P =.03). Among children with unilateral disease, the mean Ki67 proliferative index was significantly higher in children with advanced clinical disease (stages 3 and 4) (mean 81.25; SD 6.78) than in those with earlier stage disease (mean 69.50; SD 9.45) (P = 0.001). Among children with bilateral disease, however, the mean proliferative index was not significantly higher for children with advanced clinical stage. When examining all cases together, there was a significant trend toward increasing proliferative index with increasing clinical stage (P =.03). In unilateral tumors, we also found that presence of detectable pRB was associated with a lower percentage of cells expressing E2F1 (46.7% v 70.8%) (P = 0.05), whereas there was no association between presence of pRB and E2F1 among bilateral tumors. We have found that expression of some of the cell cycle markers examined varies according to laterality, suggesting underlying differences in the capacity for cell cycle regulation between these 2 forms of the disease. Differences in capacities for cell cycle regulation may account for some differences in clinical behavior. Thus, the inclusion of molecular markers may become useful adjuncts to clinicopathological staging and subsequent determination of therapy.

Age Factors↗
PubMed2001

The measurement of three dimensional dose distribution of a ruthenium-106 ophthalmological applicator using magnetic resonance imaging of BANG polymer gels.

The BANG (MGS Research Inc., Guilford, CT) polymer gel has been used as a dosimeter to determine the three-dimensional (3D) dose distribution of a ruthenium-106 (Ru-106) ophthalmologic applicator. An eye phantom made of the BANG gel was irradiated with the Ru-106 source for up to 1 h. The phantom and a set of calibration vials were scanned simultaneously in a GE 1.5 T MR imager using the Hahn spin-echo pulse sequence with a TR of 2000 ms and two TEs of 20 ms and 100 ms. The T(2) values were evaluated on a pixel-by-pixel basis using custom-built software on a DEC alpha workstation and converted to dose using calibration data. Depth doses and isodose lines of the Ru-106 eye-plaque were generated. It is concluded that the BANG gel dosimetry offers the potential for measuring the 3D dose distributions of an ophthalmologic applicator, with high spatial resolution and relatively good accuracy.

Brachytherapy↗
PubMed2001

Trichothecene and moniliformin production by Fusarium species from western Canadian wheat.

Fusarium graminearum, Fusarium culmorum, and Fusarium avenaceum, isolated from Fusarium-damaged wheat harvested in western Canada, were cultured and evaluated for mycotoxin production. Extracts of the culture media were assayed for trichothecenes by gas chromatography-mass spectrometry and for moniliformin by liquid chromatography. Deoxynivalenol (DON) was found in 28 of 42 isolates of F. graminearum and 42 of 42 isolates of F. culmorum at levels ranging from 0.5 to 25.0 microg/g. 15-AcetylDON was found in 28 of 42 isolates of F. graminearum at levels ranging from 1.0 to 7.1 microg/g. 3-AcetylDON was found in 41 of 42 isolates of F. culmorum at levels ranging from 0.8 to 13.0 microg/g. Several other trichothecenes were assayed but not detected in the culture medium. Moniliformin was present in 40 of 42 isolates of F. avenaceum at levels ranging from 1.3 to 138.1 microg/g, but was not present in any of the isolates of F. graminearum or F. culmorum.

Chromatography, Liquid↗
PubMed2000

Differential anti-inflammatory effects of immunosuppressive drugs: cyclosporin, rapamycin and FK-506 on inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2 and PGE2 production.

OBJECTIVE AND DESIGN: Cyclosporin, FK-506 and rapamycin have similar but distinct modes of interaction with cyclophilins, calcineurins and transcription factors. These immunosuppressive drugs have also been shown to inhibit cytotoxic and inflammatory responses in macrophage. Therefore, we evaluated the mechanism of action of these drugs on iNOS and COX-2 expression by macrophages, the products of which (NO and PGE2) have cytotoxic and proinflammatory activities. MATERIALS AND METHODS: The murine macrophage cell line RAW 264.7 was grown as monolayer cultures. The effects of pharmacologically relevant concentrations of cyclosporin, rapamycin and FK-506 were evaluated in the presence and absence of lipopolysaccharide (LPS) which is a known inducer of iNOS and COX-2. Subsequently the expression of iNOS and COX-2 were analyzed by Western and Northern analysis. The production of NO and PGE2 were assayed by Greiss and RIA respectively. RESULTS: Cyclosporin (1-5 microg/ml) and rapamycin (1.0-10 nM) but not FK-506 (5-10 nM) inhibited both iNOS and COX-2 expression at mRNA level which led to significant inhibition of NO and PGE2 production. CONCLUSION: These studies characterize differential mechanistic capacity of the immunophilin-binding immunosuppressive drugs (comparable to hydrocortisone) to inhibit both iNOS and COX-2 expression. Inhibition of iNOS and COX-2 mRNA accumulation by cyclosporin and rapamycin seem to be distinct. These studies also highlight potential anti-inflammatory properties of these drugs in addition to their known immunosuppressive activity.

Animals↗
PubMed2000

Immunochemical detection of molds: a review.

Molds are widely distributed in nature and cause deterioration of foods and feeds. Their mycotoxins can adversely affect human and animal health. Suitable assays for molds, therefore, are required to implement control and regulatory strategies and to develop appropriate feeding regimens for mold-infested feeds. Many different types of mold assays have been used, most of which are not reproducible or accurate. However, the immunoassays, particularly enzyme-linked immunosorbent assays (ELISAs), can be especially useful. Among these, assays that detect the water-soluble extracellular secretions of fungi, the exoantigens, are generally able to detect fungi at the genus or species level, whereas the heat-stable polysaccharides tend to be specific for one or more genus of fungi. Several species and genus (genera)-specific ELISAs have been developed using monoclonal or polyclonal antibodies against exoantigens and heat-stable polysaccharides from a wide range of fungi, including Aspergillus, Penicillium, and Fusarium species. Other assays have been developed that nonspecifically detect mold in food or feed, some using antibodies against a mixture of antigens from different fungi. These assays are highly sensitive, are easy to perform, and provide an index of the amount of mold present in the sample. Further refinement of these assays should facilitate their widespread use by food and feed processors, regulatory agencies, taxonomists, and research scientists.

Animals↗
PubMed1998

Relationships among deoxynivalenol, ergosterol and Fusarium exoantigens in Canadian hard and soft wheat.

Soluble extracellular components (exoantigens) from cultures of Fusarium graminearum and F. sporotrichioides were used to produce antisera from chickens for an indirect enzyme immunoassay. This immunoassay was used to estimate Fusarium exoantigen levels in 40 samples of fusarium head blight-infected hard red spring wheat from Manitoba, and in 50 samples of infected soft white winter wheat from Ontario. These wheat samples were also assayed for deoxynivalenol (DON), the predominant Fusarium mycotoxin, and for ergosterol, a metabolite reflecting fungal biomass. Using F. sporotrichioides antisera, the linear correlations between exoantigen level and DON content for the hard and soft wheats had coefficients of 0.80 and 0.76, respectively. With the same antisera, linear correlations between exoantigen level and total ergosterol concentration for the hard and soft wheats had coefficients of 0.66 and 0.81, respectively.

Antigens, Fungal↗
PubMed1998

Effects of acute intravenous cocaine on cardiovascular function, human learning, and performance in cocaine addicts.

Continuous non-invasive cardiovascular monitoring in eight healthy cocaine addicts receiving intravenous cocaine (0.325 mg/kg or 0.650 mg/kg) or placebo in double-blind, randomized, cross-over fashion demonstrated significant dose-dependent increases in pulse and mean arterial pressure following cocaine. Pulse and mean arterial pressure peaked 5 min post-cocaine injection and maximal response was sustained for a further 15 min and 35 min afterwards, respectively. Cocaine administration had no significant effect on peripheral oxygen saturation, and no clinically significant abnormalities of rhythm or conduction were seen on the electrocardiogram. These doses and method of single-dose intravenous cocaine administration, and our procedures for cardiovascular monitoring, appear relatively safe for laboratory studies of healthy cocaine addicts with no pre-existing cardiovascular disease. In addition, cocaine-taking (0.325 mg/kg i.v. and 0.650 mg/kg i.v.) was associated with enhanced attention (i.e. increased numbers of correct responses on the Rapid Visual Information Processing Task), but the trend towards reduced reaction time did not achieve statistical significance. Cocaine-taking resulted in a small but statistically insignificant improvement in learning on the Digit Symbol Substitution Task. These results suggest that cocaine-taking in rested subjects is associated with some cognitive enhancement.

Adult↗
PubMed1998

Isradipine prevents global and regional cocaine-induced changes in brain blood flow: a preliminary study.

The L-type calcium channel antagonist, isradipine, reduces brain ischemia in animal models of ischemic stroke. These effects of isradipine appear more pronounced in dopamine (DA) rich brain regions. These same DA-rich brain regions have also been shown to be the areas most affected by cocaine-induced ischemic changes. Using a novel quantified approach to single photon emission computerized tomography, we demonstrated that isradipine pre-treatment prevented cocaine-induced ischemic changes, especially in these DA-rich brain regions. This is the first demonstration that any medication, including isradipine, can prevent the ischemic effects of cocaine on brain blood flow. Isradipine may, therefore, be a useful therapeutic agent for the prevention of brain ischemia in cocaine addicts.

Adult↗
PubMed1998

External beam radiation therapy for choroidal neovascularization.

OBJECTIVE: This study aimed to determine the effect of external beam radiation therapy on choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). DESIGN: The study design was a nonrandomized clinical trial with an historic control group. PARTICIPANTS: A total of 91 patients were treated with external beam radiation. These patients were compared retrospectively to the 119 patients in a control group. INTERVENTION: Patients with subfoveal CNV who did not meet the criteria for laser treatment defined by published reports from the Macular Photocoagulation Study Group or who did not want laser treatment were considered for radiation therapy in a nonrandomized, prospective clinical trial. Additional entry criteria for this prospective study included visual acuity better than or equal to 20/320 on the Early Treatment Diabetic Retinopathy Study chart and a lesion size less than 12 disc areas. The patients were treated with 5 fractions of 200 cGy 6 MV external beam photons. MAIN OUTCOME MEASURES: The visual acuity measured at baseline was compared to the visual acuity after 1 year of follow-up. RESULTS: The mean baseline visual acuity of the 91 patients entered into the Radiation Study was 20/80. After 1 year, 83 patients (91.2%) completed follow-up, and their mean visual acuity dropped to 20/200. By comparison, the mean baseline visual acuity of the control patients also was 20/80, and after 1 year, the control subjects had a mean visual acuity of 20/125. At 1 year of follow-up, 49.4% of patients treated with radiation and 38.1% of the control subjects lost 3 or more lines of visual acuity (P = 0.16). CONCLUSIONS: This study found that external beam radiation using 1000 cGy in 5 fractions, a dose similar to that used in previous studies, was not effective in the treatment of CNV secondary to AMD. These results suggest that patients should not be treated with this dose of external beam radiation for CNV secondary to AMD.

Aged↗
PubMed1998

Demonstration of dose-dependent global and regional cocaine-induced reductions in brain blood flow using a novel approach to quantitative single photon emission computerized tomography.

Ischemic stroke is a common cause of morbidity and mortality in cocaine addicts. Because the previous semiquantitative single photon emission computerized tomography (SPECT) method for measuring brain blood flow does not quantify blood flow, the magnitude and specificity of cocaine's effects during drug taking has not been well established. Here, using a novel quantitative approach to SPECT, we established that intravenous cocaine administration to nine recently abstinent cocaine-dependent subjects was associated with significant decreases in global and regional brain blood flow to dopamine-rich areas such as the prefrontal, frontal temporal, and subcortical gray matter. Establishing the utility of this relatively new quantitative SPECT technique provides an important tool for the management of vascular disorders of the brain. Additionally, identifying the site-specific effects of cocaine provides targets for the development of putative therapeutic medications to attenuate or minimize ischemic stroke in cocaine addicts.

Adolescent↗
PubMed1997

The characterization of chicken antibodies raised against Fusarium spp. by enzyme-linked immunosorbent assay and immunoblotting.

Immunoassays for the detection of three Fusarium species have been developed. Chickens were immunized with the soluble antigens from within the mycelia (mycelia-soluble antigens) and the exoantigens of Fusarium sporotrichioides, Fusarium poae and Fusarium graminearum and the antigens were characterized using enzyme-linked immunosorbent assays, immunoblotting and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The cross-reactivities of antisera with eleven species of Fusarium, eleven species of fungi from other genera and the buffer-extracts of grain were determined. Antisera to the exoantigens and mycelia-soluble antigens did not cross-react with buffer-extracts of grain. The antisera against the mycelia-soluble antigens tended to cross-react with the antigens from other genera whereas the antisera against the exoantigens were genus specific. The antiserum raised against exoantigens from F. poae was species specific. The molecular weights of the immunodominant antigens from the Fusaria were above 28 kilodaltons. Antigens from Fusaria showed specific bands in SDS-PAGE gel that can be used to produce more specific antibodies. The results suggest that exoantigen immunoassay can be developed to identify Fusarium genus, whereas mycelia-soluble antigens are not suitable for immunoidentification among genus.

Animals↗