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Biomedical subjects

R Frank

Publications and source records attributed to R Frank.

At least 649 records · Page 36Linked to original sources
PubMedDate not supplied

Triazine and chloroacetamide herbicides in Sydenham River water and municipal drinking water, Dresden, Ontario, Canada, 1981-1987.

Samples of raw river water from the Sydemham River, Ontario were collected 30 to 50 times per year between 1981 and 1987 along with paired samples of drinking water from the town of Dresden. Atrazine and its metabolite, deethyl atrazine, were found in 89 to 100% of the raw water over the seven year period. Alachlor was found only in 1982, 1984 and 1985 when 2 to 17% of raw waters were contaminated. Cancellation of the registration to use alachlor at the end of 1985 resulted in no residues being found in 1986 and 1987. Cyanazine was found in 3 to 29% (1982-87), metolachlor in 19 to 27% (1984-87) and metribuzin in 2 to 7% (1982-86) of raw river water. Comparison of those residues in raw with those in drinking water revealed that chlorination of river water had no effect in reducing herbicide concentrations. During 1985 the addition of up to 50 mg/L of powdered charcoal to raw water reduced residues to near or below detection limits for s-traizine and chloroacetamide herbicides. However, in 1986, with a reduced rate of 20 mg/L of charcoal herbicide residues were only slightly reduced and in 1987 with only 5 mg/L no reductions occurred.

Acetamides↗
PubMedDate not supplied

Imaging of retroperitoneal rhabdomyosarcoma mimicking hypernephroma.

Malignant tumors that arise in the perinephric space often present a diagnostic dilemma. These retroperitoneal tumors may resemble renal carcinomas, extrahepatic lymphoma, metastatic disease, or tumors arising in other retroperitoneal organs. We present a case of a patient with a primary retroperitoneal rhabdomyosarcoma who had an extensive diagnostic workup prior to surgical intervention that was thought to be consistent with an aggressive renal cell carcinoma.

Aged↗
PubMedDate not supplied

Delineation of selective cyclic GMP-dependent protein kinase Ialpha substrate and inhibitor peptides based on combinatorial peptide libraries on paper.

Peptide libraries on cellulose paper have proven to be valuable tools for the a priori determination of substrate specificities of cyclic AMP- and cyclic GMP-dependent protein kinases (cAMP-kinase and cGMP-kinase) on the basis of octa-peptide sequences. Here, we report the extension of our peptide library screens to 12-mer and 14-mer peptide sequences, resulting in highly cGMP-kinase Ialpha selective peptides. The sequences TQAKRKKSLAMA-amide and TQAKRKKSLAMFLR-amide, with Km values for cGMP-kinase Ialpha of 0.7 and 0.26 microM and Vmax values of 11.5 and 10.9 micromol/min/mg, respectively, display a high specificity for this enzyme. Furthermore, replacing the phosphate acceptor residue serine with alanine in TQAKRKKSLAMA-amide resulted in the highly cGMP-kinase Ialpha selective inhibitor peptide TQAKRKKALAMA-amide, with inhibitor constants for cGMP-kinase Ialpha and cAMP-kinase of 7.5 microM and 750 microM, respectively. Selective cGMP-kinase inhibitors have the potential to play an important role in the elucidation of the distinct cellular functions of cGMP-kinase separate from those activated by cAMP-kinases, and, therefore, may play an important role as pharmaceutical targets. Molecular docking experiments of the most cGMP-kinase selective sequences on a molecular model of the catalytic domain of cGMP-kinase Ialpha suggest that they adopt unique conformations, which differ significantly from those observed for the cAMP-kinase-specific inhibitor PKI(5-24). Our results suggest that despite their structural similarities, cAMP-kinase and cGMP-kinase use distinct peptide substrate and inhibitor conformations, which could account for their unique substrate specificities. These findings are further supported by cAMP- and cGMP-kinase-selective inhibitor analogs with (D)-Ala residues at the inhibitory positions.

Animals↗
PubMedDate not supplied

Cyclin/PCNA is the auxiliary protein of DNA polymerase-delta.

Identification of the cellular proteins whose expression is regulated during the cell cycle in normal cells is essential for understanding the mechanisms involved in the control of cell proliferation. A nuclear protein called cyclin of relative molecular mass 36,000 (Mr 36K), whose synthesis correlates with the proliferative state of the cell, has been identified in several cell types of human, mouse, hamster and avian origin. The rate of cyclin synthesis is very low in quiescent cells and increases several fold after serum stimulation shortly before DNA synthesis. Immunofluorescence and autoradiography studies have shown that the nuclear staining patterns of cyclin during S phase have a sequential order of appearance and a clear correlation can be found between DNA synthesis and cyclin positive nuclei. The proliferating cell nuclear antigen (PCNA) and cyclin have many common properties and it has been shown that these two are identical. Recently a protein which is required by DNA polymerase-delta for its catalytic activity with templates having low primer/template ratios has been isolated from calf thymus. We report here that cyclin and the auxiliary protein of DNA polymerase-delta are identical.

Amino Acid Sequence↗
PubMedDate not supplied

Lack of ozone effects on oxygen hemoglobin affinity.

Ozone exposure has been shown to cause erythrocyte damage and thus may be affecting oxygen delivery by the red cell. Oxyhemoglobin affinity, heme-oxygen binding site interaction (Hill coefficient), and red cell 2,3-diphosphoglycerate concentrations were measured in a total of twenty-two New Zealand white rabbits exposed to ozone. Ozone exposures of 1 and 3 ppm for 4 hr in rabbits had no significant (P greater than .05) effect, immediate or delayed, on the parameters measured.

Animals↗
PubMedDate not supplied

Effects of inhaled sulfur dioxide (SO2) on pulmonary function in healthy adolescents: exposure to SO2 alone or SO2 + sodium chloride droplet aerosol during rest and exercise.

Recently we reported statistically significant changes in pulmonary functional measurements in asthmatic adolescents exposed at rest or during exercise. To demonstrate whether those results were due to the subjects' adolescence, or more likely, to their diagnosis of asthma, we repeated identical exposures in healthy adolescents. The changes after exposure to sulfur dioxide (SO2); however the changes were only slightly greater than those seen after sham exposure. After exposure at rest to 1.0 ppm SO2 + 1 mg/m3 sodium chloride (NaCl) droplet aerosol, the healthy adolescents showed small (3%) but statistically significant reductions in forced expiratory volume in one second (FEV1.0). No significant changes were seen following exposure to NaCl of SO2 alone at rest. Exposure to the SO2 modes during moderate exercise produced greater changes. Following exposure to either the SO2 + NaCl mixture or 1.0 ppm of SO2 alone, the reductions in FEV1.0 were slightly greater (6%) and prolonged compared with those seen at rest. Significant decreases also were seen in Vmax50 and Vmax75. A small decrease (4%) in FEV1.0 was seen following exposure to NaCl alone during exercise, but the change was not statistically significant. The changes seen in the healthy adolescents were slight compared to those seen in the asthmatic adolescents previously exposed (changes of 23-67%). We conclude that asthmatic adolescents are much more sensitive to the effects of inhaled SO2 than are healthy adolescents.

Adolescent↗
PubMedDate not supplied

A method for assessing small airways independent of inspiratory capacity.

Reduced forced vital capacity may confound assessment of small-airway function. In 17 healthy and 16 asthmatic volunteers, we validated a method for measuring mean expiratory flow during the middle half of the forced vital capacity, mean expiratory flow during the third quarter of the forced vital capacity, instantaneous forced expiratory flow at 50% of forced vital capacity , and instantaneous expiratory flow at 75% of forced vital capacity. These measurements were conducted at the same absolute lung volume (isovolume) when forced vital capacity was reduced voluntarily to 100%, 85%, and 75% of maximum, and the variances, expressed as the coefficients of variations, were compared. Absolute lung volumes above residual volume were determined with two reference spirograms: 100% and 75% forced vital capacity. In normals, means of flow rates at the same absolute lung volume did not differ with the three forced vital capacities, regardless of whether the 100% or 75% forced vital capacity served as the reference spirogram. Reduced forced vital capacity among asthmatics was associated with modest increases in isovolume flow rates, an effect that may underestimate airway narrowing. Intrasubject variability was least among volume-averaged flow rates (e.g., mean expiratory flow during the middle half of the forced vital capacity). Volume-adjusted flow rates can be used to assess small-airways narrowing when forced vital capacity is reduced, and volume-averaged rates provide the least variability.

Adult↗
PubMedDate not supplied

Monitoring Ontario-grown apples for pest control chemicals used in their production, 1978-86.

Between 1978 and 1986, 305 samples of apples were monitored for the residues of a wide range of pesticides used in their production. Three (1%) contained residues above the maximum residue limits (MRL) permitted under the Canadian Food and Drug Act and regulations; two involved phosalone at 5.9 and 6.2 mg/kg respectively and one involved diphenylamine at 6.7 mg/kg when the MRL was 5.0 mg/kg for both compounds. Low residues of dicofol, endosulfan, phosalone, phosmet, captan, daminozide and diphenylamine were frequently found; however they were well below the MRLs. These residue levels were correlated with survey data on the areas of the apple crop treated with specific pesticides. Residues of carbaryl, diazinon, ethion, azinophosmethyl, parathion, and dithiocarbamate fungicides were found occasionally; all were well below the MRLs and correlated with the pattern of use. No residues of PCB were found to a limit of detection of 0.01 mg/kg.

Environmental Monitoring↗
PubMedDate not supplied

Residues of insecticides and fungicides on Ontario-grown vegetables, 1986-1988.

Between 1986 and 1988, 433 composite vegetable samples representing 16 commodities were collected from farm deliveries to the marketplace in Ontario, Canada. All samples were analysed for insecticides and fungicides. The analyses included organochlorine, organophosphorus, synthetic pyrethroid, and N-methylcarbamate insecticides and dithiocarbamate, dicarboximide, and organochlorine fungicides. The commodities tested included asparagus, beans, carrots, celery, cole crops, cucumbers, lettuce, onions, peppers, potatoes, radishes, rutabagas and tomatoes. In 64% of samples, no pesticide residues were identified to the limits of detection which ranged from 0.005 to 0.05 mg/kg. A further 22% had combined insecticide and fungicide residues below 0.1 mg/kg. Most of the positive findings were a fraction of the Maximum Residue Limit permitted for each commodity under the Canadian Food and Drugs Act and Regulation. Three samples (0.7%) had residues that exceeded the MRL. These involved diazinon and parathion on celery and chlorothalonil on peppers. While some commodities had no detectable residues others had measurable residues of up to three separate pesticides. The most were found on celery, lettuce and field tomatoes.

Food Analysis↗