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M B Jones

Publications and source records attributed to M B Jones.

At least 145 records · Page 8Linked to original sources
PubMed1968

Comparison of rumen microbial inhibition resulting from various essential oils isolated from relatively unpalatable plant species.

Essential oils were isolated from eight plant species which were relatively unpalatable to sheep and deer. The inhibitory potency of these essential oils upon sheep and deer rumen microorganisms was compared, in terms of total gas and volatile fatty acid (VFA) production, by use of an anaerobic manometric technique. Inhibitory effects of oils from the eight plant species may be placed in four groups: (i) essential oils from vinegar weed (Trichostema lanceoletum) and California bay (Umbellularia californica) inhibited rumen microbial activity most; (ii) lesser inhibition was exhibited by rosemary (Rosmarinus officinalis) and California mugwort (Artemisia douglasiana) oils, followed by (iii) blue-gum eucalyptus (Eucalyptus globulus) and sagebrush (Artemisia tridentata) oils; and (iv) oils from Douglas fir (Psuedotsuga menziesii) and Jerusalem oak (chenopodium botrys) resulted in the least inhibition, when 0.3 ml of each oil was used. A highly significant correlation coefficient (r = 0.98(**)) between total gas and VFA production indicated the validity of either method to measure the activity of rumen microorganisms. Our results are discussed in relation to the hypothesis that the selectivity and voluntary consumption of ruminants are related to the characteristic odor and antibacterial action of essential oils isolated from relatively unpalatable plant species.

Animal Nutritional Physiological Phenomena↗
PubMed1967

Effect of various essential oils isolated from Douglas fir needles upon sheep and deer rumen microbial activity.

The effects of essential oils isolated from Douglas fir needles on sheep and deer rumen microbial activity were tested by use of an anaerobic manometric technique. Rumen microorganisms were obtained from a sheep which had been fed mainly on alfalfa hay and dried range grass. One deer used in this study had access to Douglas fir trees the year around, whereas the other deer had no access to Douglas fir. All of the monoterpene hydrocarbons isolated from Douglas fir needles-alpha-pinene, beta-pinene, limonene, myrcene, camphene, Delta(3)-carene, and terpinolene-promoted only slightly or had no effect on deer rumen microbial activity, whereas all of them promoted activity in sheep rumen microbes, except Delta(3)-carene and terpinolene, which inhibited activity. Of the oxygenated monoterpenes, all monoterpene alcohols-alpha-terpineol, terpinen-4-ol, linalool, citronellol, and fenchyl alcohol-strongly inhibited the rumen microbial activity of both sheep and deer. Monoterpene esters (bornyl acetate) produced mild inhibition for both sheep and deer microbes, and citronellyl acetate inhibited rumen microbial activity in sheep, whereas it promoted activity in both deer. Monoterpene aldehyde (citronellal) inhibited the activity of rumen microbes from both sheep and deer having no access to Douglas fir from the Hopland Field Station, whereas they produced no effect upon the deer having access to Douglas fir from the Masonite forest. Rumen microbial activity for sheep and deer was promoted slightly with aliphatic ester (ethyl-n-caproate). There was a marked difference between sheep and deer rumen microbes as affected by addition of the various essential oils. The monoterpene hydrocarbons promoted activity more on sheep rumen microbes than on deer, and the monoterpene alcohols inhibited sheep rumen microbial activity more than that of deer. Furthermore, the deer rumen microbes from Hopland Field Station were affected more than the deer from Masonite forest.

Animals↗
PubMedDate not supplied

Testing for behavioral contagion in a case-control design.

'Behavioral contagion' refers to an increased tendency for a behavior to be performed when socially related persons have already performed it. So understood, behavioral contagion may be involved in criminality, conduct disorder, drug abuse, suicide, and teenage pregnancy. In a recent paper we showed that contagion, when present, generates highly distinctive result patterns in survey data. These patterns allow one to infer that contagion is present even though it has not been directly observed. The present paper extends this approach to case-control designs, where, it will be shown, contagion has equally distinctive but different consequences. The analysis is illustrated with a Canadian study of conduct disorder and further evidence is presented that this condition is contagious. Limitations of the approach and alternative interpretations of results are discussed.

Adolescent↗
PubMedDate not supplied

Preferred pathways of behavioral contagion.

A behavioral disorder is "contagious" if the risk to a given individual increases when someone in that person's vicinity, family, or social group develops the disorder. So understood, behavioral contagion may be involved in criminality, conduct disorder, drug abuse, suicide, and teenage pregnancy. Previous papers have shown that contagion generates highly distinctive result patterns, from which its presence may be inferred. The patterns concern prevalence in sibships of different size and, in case-control designs, the number of susceptible sibs that affected and unaffected individuals have. The present paper extends the analysis by allowing the likelihood of transmission from one sib to another to vary according as the two sibs are of the same or opposite gender, male or female, single borns or co-twins, fraternal or identical twins. The extension is illustrated by application to data on criminality in Danish twins previously reported by other workers. We will show that the distribution of criminality by gender and zygosity is better explained in terms of behavioral contagion than by previous analyses.

Adolescent↗
PubMedDate not supplied

Temperature-dependent physiological response of Carcinus maenas exposed to copper.

The effect of temperature on the heart rate (fH) of Carcinus maenas exposed to a sublethal nominal concentration (0.5 mg l(-1)) of copper is reported. Adult, intermoult males (4 cm carapace width) were collected from Stavanger Fjord (Norway) in August (seawater TEMPERATURE=17 degrees C) and maintained in the laboratory (fed ad libitum) at 5, 15 and 25 degrees C for 7 days. Following this holding period, crabs were exposed to waterborne copper at the same temperature. After 3 days of exposure, individual fH was measured using the non-invasive Computer Aided Physiological MONitoring system (CAPMON) method. Copper-exposed individuals demonstrated significantly increased fH compared with controls at 5 and 25 degrees C (P<0.01). It is inferred that physiological function in C. maenas may be more vulnerable to copper contamination at seasonal temperature extremes (5 and 25 degrees C) than at the 'standard' test temperature (15 degrees C). Additionally, cardiac arrest observed at 5 degrees C is interpreted as a physiological response to limit copper uptake while the erratic fH in the 25 degrees C group reflected enhanced copper toxicity.

Animals↗
PubMedDate not supplied

Mysids and trace metals: disruption of swimming as a behavioural indicator of environmental contamination.

Mysids are used frequently in standard laboratory studies of acute exposure to chemical contaminants. Their value for sub-lethal measures of biological response to predict the potential effects of environmental toxicants, however, has yet to be determined. In estuaries, mysids maintain their optimum position independent of the forces of river flow and tides; therefore, any disruption of swimming behaviour will have significant implications for their survival and position maintenance. In the present study, the effects of cadmium on the swimming behaviour of the hyperbenthic estuarine mysid Neomysis integer, which occupies the heads of European estuaries, are presented. Following 7 day exposure to cadmium, swimming behaviour (ability and orientation) was disrupted at 0.5 microgram Cd(aq)2+ l-1, a significantly lower cadmium concentration than that causing mortality (7 day LC50 of 2.58 micrograms Cd(aq)2+ l-1). The results of this investigation highlight the advantages of behavioural toxicity tests for predicting the influence of pollutants and support the use of mysids for estuarine monitoring.

Animals↗
PubMedDate not supplied

Stability of lysosomal and cell membranes in haemocytes of the common mussel (Mytilus edulis): effect of low temperatures.

Expanding industrial activities in the Arctic require an urgent assessment of the toxicity of chemicals at low temperatures. Organisms acclimatized to low temperature exhibit specific adaptations. For example, the amount of unsaturated lipids is increased to maintain the fluidity of the cell membranes. It has been hypothesized that such temperature-induced alterations in membrane lipid composition may affect the stability of lysosomal and cell membranes in the common mussel, Mytilus edulis, an organism exposed to seasonal temperature extremes. As mussels may be exposed to petroleum compounds along industrialized coastlines, we tested the combined effects of exposure to low temperature and the petroleum compound, phenanthrene, on haemocyte membrane stability. Test animals, acclimated to either 0 or 10 degrees C, were exposed to phenanthrene (0 = control or 500 micrograms l-1) and haemocytes were examined using the neutral red retention assay (lysosomal stability) and a fluorescence assay (cell membrane stability). At 0 degree C, lysosomal and cell membranes from uncontaminated mussels were destabilized compared with 10 degrees C (P = 0.0005). No significant effects (P > 0.05) of phenanthrene were detected at either temperature. Possible mechanisms underlying membrane destabilization include a weaker physical resistance of the membrane due to a higher amount of unsaturated lipids, a potentially higher level of reactive oxygen radicals at low temperature and the higher susceptibility of unsaturated lipids to oxidative stress. More work is required to better understand the consequences of this membrane destabilization at low temperature on the susceptibility of the organism to pollutants.

Adaptation, Physiological↗
PubMedDate not supplied

Total oxyradical scavenging capacity and cell membrane stability of haemocytes of the Arctic scallop, Chlamys islandicus, following benzo(a)pyrene exposure.

Industrial activities, notably oil and gas industries, are expanding in the Arctic. Most of the biomarkers were developed using temperate organisms living at temperatures above 10 degrees C. Little is known about the biomarker responses of organisms living between -1.88 and 5 degrees C. Therefore, assessment of the toxicity of chemicals to cold-water adapted species is required. In this study, the Arctic scallop, Chlamys islandicus, was selected as a key species for bio-monitoring because of wide distribution in Arctic waters and its commercial value. Test animals, stored in seawater at 2 degrees C, were injected with benzo(a)pyrene (diluted in cod liver oil 5 mg ml(-1)) in the adductor muscle every 24 h for four days giving a final dose of 0, 74 and 90.6 mg kg(-1) wet weight for control, low and high dose, respectively. The biomarkers used were total oxyradical scavenging capacity (TOSC) in the digestive gland and cell membrane stability of haemocytes. TOSC values were significantly reduced (ca. 30%) in exposed groups (P < 0.05), indicating a depletion in oxyradical molecular scavengers. The antioxidant defences appeared to be overwhelmed by the reactive oxygen species as the plasma membranes of haemocytes were destabilised (P < 0.05) probably due to lipid peroxidation. These data indicate that reactive oxygen species (ROS) were produced by Arctic scallops via the metabolisation of benzo(a)pyrene at 2 degrees C.

Adaptation, Physiological↗
PubMedDate not supplied

Behavioral contagion and official delinquency: epidemic course in adolescence.

The cumulative onset curves for smoking, drinking, and sexual intercourse have been tracked through adolescence with reasonable success by recursive equations positing an "epidemic" or contagious process. The gist of these models is that the likelihood of onset in the next time period is proportional to the prevalence of the behavior among an adolescent's peers in the current time period. The present paper extends this approach to official delinquency. The fits to the data (from the Philadelphia cohort studies) are extremely tight. Several conceptual mismatches between the theory underlying the model and the model itself are discussed.

Adolescent↗
PubMedDate not supplied

Hypertensive disorders of pregnancy.

Preeclampsia/eclampsia, also known as toxemia of pregnancy, remains one of the great triad of obstetric complications. The outlook for the preeclamptic woman and the fetus has improved as a result of increased knowledge of uteroplacental-fetal physiology and of the physiologic deviations involved in preeclampsia, although the basic cause of preeclampsia remains unknown. Careful screening of women at risk for preeclampsia along with early detection and treatment can help reduce the toll taken in stillbirths, prematurity, and maternal death. Current concepts of pathophysiology are reviewed as is nursing care during the antepartum and intrapartum periods.

Female↗