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Biomedical subjects

W Orr

Publications and source records attributed to W Orr.

At least 37 records · Page 2Linked to original sources
PubMed1984

Mutants suppressing in trans chorion gene amplification in Drosophila.

Two recessive female-sterile mutants, K451 and K1214 , disrupt chorion formation by causing underproduction of all major chorion proteins. We present evidence that this effect is due to underaccumulation of the chorion mRNAs and that, in turn, this is caused by a substantial reduction in the level of chorion gene amplification. The mutants are X-linked but located at two sites far from the chorion gene cluster at 7F1 -2; their effect is even more pronounced on the third chromosome chorion gene cluster, and thus the wild type gene must act in trans. The time course of amplification in mutant and wild-type follicles is documented.

Animals↗
PubMed1981

Dose-related effects of flurazepam on human sleep-walking patterns.

Two consecutive nights of flurazepam at each of 15, 26, and 45 mg were compared to placebo in a Latin-square double-blind crossover design using 24 healthy young-adult males. Flurazepam had significant hypnotic effects on objective and subjective measures of efficacy: shorter sleep latency, longer sleep time, and fewer awakenings. It also induced morning sedation along with decrements in cognitive performance. Flurazepam had dose-related impacts on both human and computer-scored EEG-EOG parameters: less stages 3 + 4 and decreased EEG delta, less stage 1 REM and decreased REM density, more stage 2 and increased EEG spindling. Also, EEG alpha and movement artifact were decreased and EEG beta was increased. Only a few of the EEG-EOG variables and none of the subjective indices had cumulative changes on the two drug nights. Stage shifting was unaffected at the two lower doses on the first night but decreased at all three dose levels on the second night; percent stages 3 + 4 was unaffected on the first night but decreased at all dose levels on the second night. The rate of delta waveform activity was also diminished by a greater amount on the second night. This study conclusively established that flurazepam affects the EEG-EOG architecture of sleep on each of the first two nights of administration.

Adult↗
PubMed1981

Sterol ester hydrolase in Fusarium oxysporum.

Two electrophoretically different forms of sterol ester hydrolase (EC 3.1.1.13) were obtained from the cytoplasmic extract of the mycelia of Fusarium oxysporum. The entities, estimated at 60,000 (I) and 15,000 (II) molecular weights, were obtained in Sephadex G100 column chromatography of the ammonium sulfate precipitate from the cytoplasmic extract. A third form III, 75,000 MW, was obtained from the culture filtrate. The activity of the enzyme was increased by Triton X-100 and was not inhibited by p-chloromercuribenzoate (PCMB), a sulfhydryl reagent. The enzymes I and II were inhibited differentially by NaCl. The optimal activities of forms I, II and III occurred at pH 4.8, pH 8.0 and pH 7.0, respectively. The apparent Km values of 7.7 X 10(-5), 8.3 X 10(-5) and 10.5 X 10(-5), respectively, indicate a similar order of affinity for cholesteryl oleate at pH 7.1. The rate of hydrolysis of cholesteryl esters were in the order: linoleate greater than oleate greater than valerate greater than butyrate greater than acetate. Cholesteryl benzoate and palmitate were not hydrolyzed. The properties of the microbial enzyme are discussed in relation.

Carboxylic Ester Hydrolases↗
PubMed1981

Antimicrobial effects of clofibrate on the wheat pathogen Fusarium culmorum.

The biological effects of clofibrate (ethyl p-chlorophenoxy-isobutyric acid) on the growth and metabolism of the soil-borne wheat pathogen Fusarium culmorum, were examined. In mid log phase (16 hr) cultures both phenylalanine uptake and secondary spore production were stimulated at 0.1 microM concentration; the net sterol content was reduced 50% at 0.35 microM; oxygen uptake was stimulated at 0.1 mM; growth was inhibited 50% at 0.1 mM concentration. Both phenylalanine and oxygen uptake were inhibited at 1.0 mM and pyruvate dehydrogenase activity was reduced 50% at 50 mM concentration of clofibrate. The data indicate that clofibrate affects a number of biological and enzyme systems. The inhibitory effect on the growth of the pathogen suggest a potential use of hypolipidemic agents like clofibrate as an antifungal agent for seed protection.

Biological Transport, Active↗
PubMed1981

Dose-related effects of phenobarbitone on human sleep-waking patterns.

1 Twenty-four healthy male subjects had two consecutive drug nights at 2-week intervals using placebo and 80, 140 and 240 mg doses of phenobarbitone in a double-blind cross-over design. 2 Phenobarbitone produced significant dose-related decreases in sleep latency and number of awakenings, along with increased total sleep time. 3 Both subjective and objective measures of sleep indicated the presence of cumulative (first v second night) effects of phenobarbitone, especially decreases in the number of awakenings and in delta waveform activity. 4 Measures of REM sleep were highly sensitive to phenobarbitone. The high dose decreased REM density to 30% of baseline on the first night and to 18% on the second night. 5 EEG alpha activity was decreased, beta activity was increased and sigma spindle activity was unaffected by phenobarbitone during sleep. 6 Subjects experienced some impairment of cognitive performance along with residual sedation the following morning.

Adult↗
PubMed1980

Adhesive characteristics of tumor cell variants of high and low tumorigenic potential.

A variant subpopulation of C57BL/6 mouse fibrosarcoma cells that had very low tumorigenic potential was isolated from a highly tumorigenic parent fibrosarcoma cell culture. The adhesive characteristics of parent cells and variant cells were compared. The low-tumorigenic variant cells were released from the surfaces of plastic dishes, from protein-coated dishes, or from monolayers of fibroblasts or endothelial cells by protease treatment much more readily than were the parent cells. There was no difference between the variant cells and the parent cells in EDTA sensitivity or sensitivity to mechanical agitation under the conditions used. Also, no difference existed between the variant cells and the parent cells in rates of attachment to the surfaces of plastic dishes or to monolayers of endothelial cells. The variant cells were characterized by high levels of chymotrypsin-like esterase activity (two to three times increased over parent cell levels), but there was only a slight difference between the variant cells and the parent cells in caseinolytic or fibrinolytic activity.

Animals↗
PubMed1979

Chemotactic responses of tumor cells to products of resorbing bone.

To explore possible mechanisms for the metastasis of malignant cells to bone, a model of tumor cell migration was developed, using Walker carcinosarcoma or malignant lymphoma cells. It was found that bone contains a factor that is strongly chemotactic for tumor cells. This factoor is released by a variety of agents that induce resorption of bone.

Animals↗
PubMed1979

Chemotactic factor for tumor cells derived from the C5a fragment of complement component C5.

Previously, we have stablished that the fifth component of complement (C5) serves as an important source of mediators that have locomotory (chemotactic) activity for leukocytes and tumor cells. C5a, a fragment (Mr 11,200) derived from the NH2-terminal portion of the alpha chain of C5, is the major chemotactic peptide for leukocytes. The present studies demonstrate that cleavage of C5a with trypsin generates a derivative peptide that is chemotactic for tumor cells (Walker carcinosarcoma). This fragment has an estimated Mr of 6000 as assessed by gel filtration and does not require the COOH-terminal arginine of C5a, because equivalent amounts of chemotactic activity for tumor cells can be generated from des-Arg-C5a by digestion with trypsin. The C5a-derived chemotactic peptide for tumor cells demonstrates peak activity at approximately 1 pM. These studies emphasize the key role of the C5a region of the C5 molecule in the generation of peptides that affect locomotory responses of cells.

Animals↗
PubMed1979

Cell-associated proteases affect tumour cell migration in vitro.

The in vitro migratory activity of mouse fibrosarcoma cells in medium containing either foetal calf serum or normal human serum was studied. These 2 sera were studied because foetal calf serum contains high levels of protease inhibitor activity while human serum contains much less. The cells migrated actively in medium with foetal calf serum but migration was greatly inhibited in human serum-containing medium. When protease inhibitors such as soybean trypsin inhibitor, lima bean trypsin inhibitor and bovine pancreas trypsin inhibitor were added to human serum-containing medium cell migration was supported almost as effectively as in medium with foetal calf serum. Addition of epsilon-amino-n-caproic acid to human serum or depletion of the plasminogen from human serum did not enable it to support enhanced migration. epsilon-amino-n-caproic acid actually inhibited migration. A variant cell population with elevated levels of caseinolytic activity and elevated levels of activity against the substrate n-acetyl-DL-phenylalanine-beta-naphthyl ester (a substrate specific for chymotrypsin-like enzymes) was isolated from the parent cells. When the variant cells were compared to the parent cells regarding migratory activity in foetal calf serum or human serum-containing medium, the variant cells showed much less activity. Only a few, widely scattered variant cells migrated in the human serum-containing medium. These data suggest that a cell-associated factor interferes with the migration of the cells in medium with human serum. This factor apparently is neutralized in medium sontaining human serum to which protease inhibitors with antitrypsin activity have been added.

Animals↗
PubMed1978

Hydroxymethylglutaryl-coenzyme A reductase. Purification and properties of the enzyme from Fusarium oxysporum.

The hydroxymethylglutaryl-coenzyme A reductase (mevalonate:NADP+ oxidoreductase, EC 1.1.1.34) system in Fusarium oxysporum, a soil inhabiting plant pathogen, has been examined. Two forms of the enzyme catalyzing the conversion of hydroxymethylglutaryl-coenzyme A were obtained in the supernatant after precipitation at 75% (NH4)2SO4 saturation of the soluble culture extract which was previously separated from cell wall, mitochondria and microsomes. The two forms of the enzyme were separated electrophoretically. A third form, contained in the precipitate obtained at 35--75% (NH4)2SO4 saturation of the same extract, was further purified by Sephadex G-50 column chromatography. This purified form moved as a single band in sodium dodecyl sulphate electrophoresis and in immunological tests and has a molecular weight of 11 000. The apparent Michaelis constant for the substrate hydroxymethylglutaryl-coenzyme A is 21 micron at 2 micron NADP. NADPH is a more efficient reductant on a molar basis than NADH for the deacylation of the hydroxymethylglutaryl-coenzyme A substrate. Optimum activity of the enzyme was obtained at pH 7.4 and 37 degrees C. The enzyme demonstrated no cold sensitivity but rather was more stable at 4 degrees C than at 25 degrees C. The protection with dithiothreitol, though minimal compared to other systems, was more effective at the higher temperature.

Fusarium↗
PubMed1978

Quantitation of leukotaxis in agarose by three different methods.

The agarose method for measuring chemotaxis has been rigorously examined by a variety of quantitative approaches, including measurements of the distance of cell migration ('leading front'), counts of total numbers of migrated cells, and counts of migrated cells in single planes. These methodologies are described in detail. It is demonstrated for the first time that the results are dependent on the concentration of chemotactic factor. Results obtained by the three quantitative methods are similar. Measurement of cells migrating in a single plane is preferable because this method is reliable and relatively simple. The assay conforms to a pattern determined by checkerboard analysis that confirms a true chemotactic response.

Animals↗
PubMed1978

Quantitative comparisons of various biological responses of neutrophils to different active and inactive chemotactic factors.

The effects of chemotactic factors on rabbit neutrophils were evaluated measuring cell migration in modified Boyden chambers and under agarose, in lysosomal enzyme release, leukocyte aggregation, and in vivo neutropenia. Chemotactins employed included the complement-derived C3 and C5 fragments, the bacterial chemotactic factor from culture supernatant fluids of Escherichia coli, and the synthetic chemotactic factors Met-Leu-Phe and formyl-Met-Leu-Phe. A consistent parallelism was found in all the leukocyte responses to a given chemotactic factor. In no instance, with any of the five chemotactic factor preparations, did cells responding in one assay system fail to respond in the four other assay systems, suggesting a common event in all of the cell responses. Boyden chamber chemotaxis was consistently the most sensitive assay; the agarose assay was, in general, less sensitive by a factor of 100 fold. Enzyme release approached, in cell sensitivity to chemotactic factors, that of the Boyden chamber assay. In general, in vitro leukocyte aggregation and in vivo neutropenia were considerably less sensitive assays. Chemotactic factor inactivator (CFI) purified from human serum destroyed in parallel all biological activities of C3 and C5 chemotactic factors but had no effect on the bacterial chemotactic factor and the activities of synthetic chemotactic peptides.

Aminopeptidases↗
PubMed1978

Comparison of cell attachment and caseinolytic activities of five tumour cell types.

We have examined the ability of 5 tumour cell types to attach to plastic flasks in medium containing either 10% foetal calf serum or 10% normal human serum and compared this ability with cell-associated caseinolytic activity. The cell types used included fibrosarcoma cells which were obtained from a methylcholanthrene-induced tumour in a C57 BL/6 mouse, the SV40-transformed 3T3 (BALB/c) cells, the Walker carcinosarcoma cells and 2 lines of HeLa cells. All 5 cell types attached to the flasks and spread out efficiently in medium containing 10% foetal calf serum. The walker carcinosarcoma cells and the 2 lines of HeLa cells also attached efficiently in medium containing 10% normal human serum and grew into monolayers in this medium. These 3 cell types had no detectable caseinolytic activity. The fibrosarcoma cells and the SV40-transformed 3T3 (BALB/c) cells did not attach in normal human serum-containing medium. These 2 cell types had readily detected caseinolytic activity. Normal human serum and foetal calf serum were compared for levels of protease-inhibitor activity. Human serum was found to have less activity than foetal calf serum against both trypsin and plasmin as well as the cell-associated caseinolytic activity. The low level of protease inhibitor activity in normal human serum may contribute to the inability of this serum to support the attachment of cells with detectable protease activity because the addition of protease inhibitors such as soybean trypsin inhibitor, lima bean trypsin inhibitor and bovine pancreas trypsin inhibitor to normal human serum dramatically enhanced cell attachment. In contrast to this, the addition of E-amino-n-caproic acid to normal human serum and the removal of plasminogen from normal human serum did not enhance its capacity to support cell attachment.

Animals↗