Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Database
Language
Publication year range
1.
Aquat Toxicol ; 245: 106128, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35255276

ABSTRACT

The risks to aquatic wildlife from spills of diluted bitumen (dilbit) into inland waters are poorly understood. In this paper, we describe the response of larval wood frogs (Rana sylvatica) to hydrocarbons and other compounds released from experimental spills of dilbit in a temperate boreal lake. To simulate a wide range of environmentally relevant oil spill scenarios, different volumes of Cold Lake Winter Blend dilbit (0, 1.5, 2.9, 5.5, 18, 42, 82, and 180 L) were added to 10 m diameter in-lake limnocorrals. Larvae (n = 360) were reared (from Gosner Stage (GS) 25 to ∼42) in land-based aquatic microcosms, where they were first exposed to clean water during a 2-week baseline phase, and then (at GS ∼30), to contaminated water withdrawn from the limnocorrals for 3 weeks. We observed no statistically significant trends in survival, growth, or development of larvae as a consequence of exposure to the chemical compounds released from naturally weathered dilbit. Likewise, neither cytochrome P450 1A biomarkers nor levels of thyroid hormones in wood frogs near metamorphic climax were significantly related to volume of the oil spills. However, there was a modest statistically significant decrease in larval activity (up to 8.7% relative to the control), but no change in other behavioral metrics (i.e., sociality or space use). Our work adds to the limited body of literature on the effects of unconventional oils on aquatic wildlife and helps to inform risk assessments regarding pipeline projects.


Subject(s)
Lakes , Water Pollutants, Chemical , Animals , Hydrocarbons , Lakes/chemistry , Larva , Ranidae , Water Pollutants, Chemical/toxicity
2.
Eur J Appl Physiol ; 120(7): 1519-1530, 2020 Jul.
Article in English | MEDLINE | ID: mdl-32350595

ABSTRACT

PURPOSE: We investigated the influence of a change in stride frequency on physiological and perceptual responses during forward and backward running at different body weight support (BWS) levels. METHODS: Participants ran forward and backward at 0% BWS, 20% BWS, and 50% BWS conditions on a lower body positive pressure treadmill. The stride frequency conditions consisted of forward and backward running at preferred stride frequency (PSF), PSF + 10%, and PSF-10%. We measured oxygen uptake ([Formula: see text]O2), carbon dioxide production, heart rate (HR), muscle activity from the lower extremity, and rating of perceived exertion (RPE). Furthermore, we calculated the metabolic cost of transport (CoT). RESULTS: [Formula: see text]O2, HR, CoT, and muscle activity from the rectus femoris were significantly different between stride frequency conditions (P < 0.05). [Formula: see text]O2, HR, and CoT during running at PSF + 10% were significantly higher than when running at PSF, regardless of running direction and BWS (P < 0.05). However, RPE was not different between stride frequency conditions (P > 0.05: e.g., 12.8-13.8 rankings in RPE for backward running at 0% BWS). CONCLUSIONS: Manipulation of stride frequency during running may have a greater impact on physiological responses than on perceptual responses at a given speed, regardless of running direction and BWS. Individuals who need to increase their physiological demands during running may benefit from a 10% increase in stride frequency from the PSF, regardless of BWS and running direction.


Subject(s)
Body Weight/physiology , Muscle, Skeletal/physiology , Physical Exertion/physiology , Running/physiology , Adult , Exercise Test , Female , Heart Rate/physiology , Humans , Male , Orthotic Devices , Oxygen Consumption/physiology , Quadriceps Muscle/physiology , Young Adult
3.
Bioorg Med Chem Lett ; 17(3): 832-5, 2007 Feb 01.
Article in English | MEDLINE | ID: mdl-17107794

ABSTRACT

We have identified a novel series of potent MCH-R1 antagonists based on l-arginine. As predicted by computational methods, there was an activity dependence on the pi-electronic character of the aromatic systems corresponding to the amino-terminus of these molecules. These results have enhanced our understanding of the MCH-R1 receptor and the potential for a predictive homology model.


Subject(s)
Arginine/pharmacology , Receptors, Somatostatin/antagonists & inhibitors , Cell Line , Chromatography, High Pressure Liquid , Humans , Luciferases/genetics , Models, Molecular , Molecular Conformation , Structure-Activity Relationship
4.
Bioorg Med Chem Lett ; 17(2): 522-6, 2007 Jan 15.
Article in English | MEDLINE | ID: mdl-17070048

ABSTRACT

A novel series of 3-morpholino rifamycins in which the C25 acetate group was replaced by a carbamate group were prepared and found to exhibit significantly improved antimicrobial activity than rifampin against Mycobacterium smegmatis. Further characterization of such compounds suggests that relatively large groups attached to the rifamycin core via a C25 carbamate linkage prevent inactivation via ribosylation of the C23 alcohol as catalyzed by the endogenous rifampin ADP-ribosyl transferase of M. smegmatis. SAR studies of the C25 carbamate rifamycin series against M. smegmatis and other bacteria are reported.


Subject(s)
ADP Ribose Transferases/metabolism , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/metabolism , Rifamycins/chemical synthesis , Rifamycins/metabolism , Drug Resistance, Bacterial , Escherichia coli/drug effects , Magnetic Resonance Spectroscopy , Microbial Sensitivity Tests , Mycobacterium smegmatis/drug effects , Mycobacterium smegmatis/genetics , Pseudomonas aeruginosa/drug effects , Rifampin/pharmacology , Staphylococcus aureus/drug effects , Structure-Activity Relationship
SELECTION OF CITATIONS
SEARCH DETAIL
...