A method for chronic intravenous infusion in freely moving rats.
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Biomedical subjects
J D Davis
Publications and source records attributed to J D Davis.
A versatile and reliable printing counter.
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Animals↗
The impact of milk-derived unconditioned and conditioned negative feedback on the microstructure of ingestive behavior.
We describe at the microstructural level the impact of unconditioned and conditioned negative feedback on the licking behavior of the rat. Six groups of rats were trained to ingest one of six different dilutions of sweetened milk (0.5:1, 1:1, 2:1, 4;1, 8:1, and 16:1, water to milk ratios) under real feeding conditions until intake was stable. Then they were given five sham-feeding tests with the same solution. We compared the size of the clusters (SC) and their number (NC) during the 15-min period when intake rate was declining in the real-feeding test with SC and NC during the corresponding 15-min period in the following sham-feeding test. Intake increased significantly over the five sham-feeding tests with the two highest concentrations, indicating the extinction of conditioned negative feedback. With these two solutions, we compared the microstructure of licking behavior in the first with that in the fifth sham-feeding test to determine if conditioned negative feedback affected SC or NC or both. The effect of both unconditioned and conditioned negative feedback on licking behavior was to decrease the number of clusters without affecting their size. We conclude that negative feedback derived from the accumulation of milk in the gastrointestinal tract decreases the probability of initiating a bout of licking during a pause. It has no effect on the ability to continue a bout of licking once it has begun.
Animals↗
Corticotropin-releasing factor decreases meal size by decreasing cluster number in Koletsky (LA/N) rats with and without a null mutation of the leptin receptor.
The homozygous mutant Koletsky rat is a monogenic form of obesity and hyperphagia due to a null mutation of the leptin receptor (lepr(fak)). To investigate if the lack of leptin action on the brain of homozygous mutants affected the inhibitory potency of corticotropin-releasing factor (CRF) on meal size, artificial cerebrospinal fluid or one of five doses of CRF was administered through third ventricular cannulas in 8 +/+, 10 +/fa(k), and 8 fa(k)/fa(k) rats 15 min before access to 20% sucrose in lickometer tubes for 30 min. CRF had equivalent inhibitory potency in fa(k)/fa(k) and +/+ rats. Thus, the complete lack of leptin action in fa(k)/fa(k) rats did not change the inhibitory potency of CRF. CRF was significantly more potent, however, in +/fa(k) rats than in the other two genotypes. Thus, the heterozygote condition of this mutation did not function as a classical recessive mutation for this behavioral phenotype. Despite these differences in potency, microstructural analysis revealed that CRF decreased intakes in all three genotypes by decreasing the number of clusters of licking without changing the size of clusters.
Animals↗
A behavioral analysis of the ingestion of glucose, maltose and maltooligosaccharide by rats.
Glucose, maltose, and Polycose are stimuli that differ in their effectiveness in stimulating ingestion in the rat. To understand better how variation in glucose chain length affects the ingestion of these compounds, we compared the effect of six concentrations of glucose, maltose, and maltooligosaccharide (MOS) on the microstructure of the licking behavior of the rat. At the three lowest concentrations the order of effectiveness in stimulating ingestion was MOS > maltose > glucose. At the three highest concentrations, there were no differences among the three compounds in volume ingested. As measured by initial rate of licking, the orosensory stimulating effectiveness of the three compounds were ordered as MOS > maltose > glucose. The magnitude of the negative feedback signals were very similar for MOS and maltose and greater than glucose at all but the highest two concentrations of glucose, suggesting that glucose chain length, not caloric density, is responsible for the differences in the magnitude of negative feedback. With the three lowest concentrations, the ordering of the compounds in their ability to stimulate intake depended on orosensory stimulating ability.
Animals↗
Recurrent mycetoma of the foot.
Mycetoma, also known as madura foot, is a local, chronic, slowly progressive disease with the classic presentation involving tumefaction, multiple draining sinuses, and grain-filled pus. It is primarily produced by either a bacteria (actinomycetoma) or a fungal (eumycetoma) organism. Determining the causative organism is fundamental to the treatment process. All types of mycetoma infections should be treated with early surgical debridement and tissue culture. Tissue should be sent for gross, microscopic, and histopathologic evaluation. In addition to surgical management, these patients should be managed adjunctively with a prolonged course of chemotherapy. Patients with actinomycetoma are treated with an antibiotic and can expect to have a clinical cure with little chance for recurrence, whereas, patients with eumycetoma are treated with an antifungal agent and usually do poorly with a high rate of recurrence. The case presented involved an infection due to Actinomadura madurae (Nocardiaform madurae) and demonstrates successful treatment with surgical resection and prolonged doxycycline chemotherapy.
Actinomycetales↗