Outbreak of diarrheal illness in attendees at a Ukrainian dance festival, Dauphin, Manitoba--May 2001.
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
D Nowicki
Publications and source records attributed to D Nowicki.
Role of the endogenous nitric oxide in the vasodilatory tone and CO2 responsiveness of the rostral ventrolateral medulla microcirculation in the rat.
The study was designed to check the role of endogenous NO in maintaining the vasodilatory tone and in mediation of local cerebral blood flow (CBF) responses to CO2 in rostral ventrolateral medulla (RVLM) in the rat. The ventral surface of the medulla was exposed and CBF in the RVLM continuously recorded with a laser-Doppler flowmeter. Local vascular resistance (CVR) was estimated as the ratio of mean arterial pressure (MAP) to CBF. During 1 min exposure to 10% CO2 in oxygen PaCO2 rose from 39.9 +/- 2 mm Hg to 89.7 +/- 4.6 mm Hg and pH fell from 7.4 +/- 0.04 to 7.1 +/- 0.03. After intravenous administration of 15 mg/kg L-NAME (Nitro-L-arginine-methyl ester) MAP increased by 43 +/- 2.9 mm Hg (p < 0.001), local CBF increased by 33 +/- 6% (p < 0.001) and CVR increased by 17 +/- 6% (p < 0.01). L-NAME significantly reduced CBF flow response to 60 s hypercapnia from 47 +/- 9% (p < 0.001) before administration of L-NAME to 14 +/- 5% (p < 0.001). This effect was due to reversal by L-NAME of a pressor response to hypercapnia to a depressor response. The attenuation of CVR response to CO2 by L-NAME was too small to account alone for the significant reduction of local CBF responsiveness to hypercapnia. We conclude that endogenous NO plays a role in maintaining a local vasodilatory tone in RVLM, but it is less significant than in the cortical microcirculation. NO is not a major mediator in the increase in local CBF in RVLM during brief hypercapnia. Endogenous NO is critical for the neurogenic pressor response to brief hypercapnia.
Animals↗
Spinal segmental sympathetic outflow to cervical sympathetic trunk, vertebral nerve, inferior cardiac nerve and sympathetic fibres in the thoracic vagus.
The spinal segmental localization of preganglionic neurons which convey activity to the sympathetic nerves, i.e. vertebral nerve, right inferior cardiac nerve, sympathetic fibres in the thoracic vagus and cervical sympathetic trunk, was determined on the right side in chloralose anaesthetized cats. For that purpose the upper thoracic white rami were electrically stimulated with a single pulse, suprathreshold for B and C fibres, and the evoked responses were recorded in the sympathetic nerves. The relative preganglionic input from each segment of the spinal cord to the four sympathetic nerves was determined from the size of the evoked responses. It was found that each sympathetic nerve receives a maximum preganglionic input from one segment of the spinal cord (dominant segment) and that the preganglionic input gradually decreased from neighbouring segments. The spinal segmental preganglionic outflow to the cervical sympathetic trunk, thoracic vagus, right inferior cardiac nerve and vertebral nerve gradually shifted from the most rostral to the most caudal spinal cord segments. In some cases, a marked postganglionic component was found in the cervical sympathetic trunk. It was evoked by preganglionic input from the same spinal cord segments which transmitted activity to the vertebral nerve. These results indicate that there is a fixed relation between the spinal segmental localization of preganglionic neurons and the branch of the stellate ganglion receiving the input from these neurons.
Animals↗
Control of the heart rate by sympathetic nerves in cats.
Pre- and postganglionic sympathetic nerves were electrically stimulated and heart rate was recorded in chloralose-anaesthetised cats. The vagal nerves and white rami were cut on both sides. Electrical stimulation was performed with a 15- or 30-s train of 0.2-ms pulses at a frequency of 30 Hz. The control heart rate was 150 beats/min. Heart rate was increased when the T3 white ramus on the left (52 beats/min above control) and T3, T4 white rami on the right side (100 beats/min above control) were stimulated electrically. The magnitude of the heart rate increase declined when the neighbouring thoracic white rami were stimulated. The increase of the heart rate was caused by group B preganglionic fibres. Electrical stimulation of the sympathetic fibres in the right vagus nerve and the right inferior cardiac nerve increased the heart rate by 92 beats/min and by 67 beats/min above the control level respectively. Electrical stimulation of the left inferior cardiac nerve, the left middle cardiac nerve and the sympathetic fibres in the left vagus nerve resulted in an increase of the heart rate of 43 beats/min, 30 beats/min and 49 beats/min from the control level respectively. This indicates that a majority of the preganglionic cardiac sympathetic fibres, whose activity influences the heart rate, originate from the T3 and T4 segments of the spinal cord. The majority of the postganglionic cardiac sympathetic fibres which affect the heart rate are located in the vagal nerves.
Adrenergic Fibers↗
Schistosoma mansoni: analysis of cercarial transformation methods.
Four methods of transforming cercariae to schistosomulae in vitro in ELAC buffer (pH 7.2, 37 C, 0-6 hr incubation) were compared in relation to biochemical and ultrastructural characteristics. The transformation methods used were chemical (3 mM linoleate), mechanical (centrifuge/vortex), mechanical/chemical, and heat (incubation at 37 C). Ultrastructural characteristics examined were based on the presence or absence of glycocalyx, heptalaminate membrane, cyton granules, and nuclear condition. Two EM fixation methods were used. Biochemical parameters assayed were loss of water tolerance (uptake of trypan blue dye), eicosanoid biosynthesis (PGE, LTB4, and 5-HETE), protein synthesis (leucine uptake), RNA synthesis (uracil and orotic acid uptake), and DNA synthesis (thymidine uptake). EM characteristics were remarkably similar for all transformation methods except heat incubation, with transformed cercariae evidencing the characteristics of schistosomulae (cyton granule migration, absence of glycocalyx and heptalaminate membrane); however, euchromatic nuclei could not be demonstrated using in vivo or in vitro transformation methods. Despite the ultrastructural similarities between transformation methods, biochemical data demonstrated that the resultant organisms were quite different. The chemical transformation method gave the highest rate of loss of water tolerance and eicosanoid production. RNA and protein synthesis were not correlated to ultrastructural changes and were highest in those organisms undergoing mechanical transformation methods, significantly higher than in those cercariae transformed by the chemical method. DNA synthesis was not demonstrated using any transformation method, although thymidine uptake did occur. Our data indicate substantial biochemical differences exist between morphologically similar organisms. Thus, experiments using any type of artificially transformed schistosomule must be interpreted with caution until additional biochemical and physiological studies on cercarial transformation are undertaken.
Animals↗
Longitudinal distribution of negative cord dorsum potentials following stimulation of afferent fibres in the left inferior cardiac nerve.
Cord dorsum potentials were recorded along the spinal cord following electrical stimulation of afferent fibres of the left inferior cardiac nerve in chloralose anaesthetized cats. The potentials were more pronounced in spinal than in intact cats. Afferent fibres which generated cord dorsum potentials in the cervical spinal cord were localized mainly in T2 and T3 and to a smaller extent in C8 and T1 dorsal roots. The responses consisted of two waves: with short (7.0 ms; N3 wave) and long (56 ms; N4 wave) latency to the onset of potentials. N3 and N4 waves were generated by group III and group IV afferent fibres, respectively. The N3 wave was maximal at C8 and T1 spinal cord level and could be detected at least 5-6 segments rostrally from the level of afferent input responsible for its generation. The N4 wave could be detected at least 4 segments rostrally from its afferent fibre input. We conclude that afferent fibres from the left inferior cardiac nerve activate neurones in the cervical spinal cord. The implications of such finding are discussed.
Animals↗
Effect of methylazoxymethanol acetate on rat liver nuclear and nucleolar RNA synthesis.
The effect of methylazoxymethanol acetate on rat liver nuclear and nucleolar RNA synthesis is investigated at various doses (5 to 50 mg/100 g body weight) and for various lengths of time (1 to 24 hr). The results show that this carcinogen is a potent inhibitor of both nuclear and nucleolar RNA synthesis. Like other carcinogens studied previously in this laboratory, e.g., N-hydroxy-2-acetylaminofluorene, aflatoxin B1, and actinomycin D, methylazoxymethanol acetate inhibits RNA synthesis at multiple sites. It impairs chromatin template function and selectively inhibits the activity of RNA polymerase II. Experimental evidence suggests the mechanism of inhibition of RNA polymerase II activity is due to a decrease in catalytic efficiency rather than in the total number of the enzyme. In addition, it is found that methylazoxymethanol acetate induces a dramatic condensation of nucleoplasmic chromatin.
Animals↗
The gingival bleeding time index.
Recent studies have supported an emphasis on gingival bleeding indices for detection of inflammation. The purposes of the present study were: (1) to evaluate the relationships between the time necessary for stimulated gingival bleeding to occur and both gingival fluid flow and Löe's gingival index, and (2) to develop a clinical index based on gingival bleeding time. In the first part of the study, the elapsed time for gingival bleeding to first occur after sulcular stimulation was correlated with the gingival index and fluid flow on 150 gingival units. A high correlation was found between bleeding time with both the gingival index and exudate flow. A bleeding time index based on a scattergram of the data obtained in part I of the study was then formulated and evaluated in a similar fashion on an additional 172 gingival units. Results indicate a high correlation between the bleeding time index and the other indices. It is concluded that the bleeding time index may be used by itself as an accurate and objective clinical tool to evaluate gingival inflammation.
Gingival Crevicular Fluid↗