PubMed Health⌕ Search

Biomedical subjects

C T Drake

Publications and source records attributed to C T Drake.

27 records · Page 2Linked to original sources
PubMed1994

Dynorphin opioids present in dentate granule cells may function as retrograde inhibitory neurotransmitters.

The granule cell population response to perforant path stimulation decreased significantly within seconds following release of endogenous dynorphin from dentate granule cells. The depression was blocked by the opioid receptor antagonists naloxone and norbinaltorphimine, suggesting that the effect was mediated by dynorphin activation of kappa 1 type opioid receptors. Pharmacological application of dynorphin B in the molecular layer was effective at reducing excitatory synaptic transmission from the perforant path, but application in the hilus had no significant effect. These results suggest that endogenous dynorphin peptides may be released from a local source within the dentate molecular layer. By light microscopy, dynorphin-like immunoreactivity (dynorphin-LI) was primarily found in granule cell axons in the hilus and stratum lucidum with only a few scattered fibers evident in the molecular layer. At the extreme ventral pole of the hippocampus, a diffuse band of varicose processes was also seen in the molecular layer, but this band was not present in more dorsal sections similar to those used for the electrophysiological studies. Electron microscopic analysis of the molecular layer midway along the septotemporal axis revealed that dynorphin-LI was present in dense-core vesicles in both spiny dendrites and unmyelinated axons with the majority (74%) of the dynorphin-LI-containing dense-core vesicles found in dendrites. Neuronal processes containing dynorphin-LI were observed throughout the molecular layer. The results suggest that dynorphin release from granule cell processes in the molecular layer regulates excitatory inputs entering the hippocampus from cerebral cortex, thus potentially counteracting such excitation-induced phenomena as epileptogenesis or long-term potentiation.

Animals↗
PubMed1991

Characterization of Vicia villosa agglutinin-labeled GABAergic interneurons in the hippocampal formation and in acutely dissociated hippocampus.

The distribution, morphology, and ionic conductances of Vicia villosa agglutinin (VVA)-labeled cells were examined in the rat hippocampal formation. The heaviest labeling and highest density of labeled neurons were found in the subicular complex. Lighter VVA-labeling and fewer labeled cells were found in hippocampal strata pyramidale, oriens, and alveus. VVA-labeled cells were found to be heterogeneous morphologically, including multipolar, bipolar, and basket-like shapes. The majority of VVA-labeled cells contained GABA and parvalbumin immunoreactivity; thus VVA-labeled cells in the hippocampal formation resemble previously described VVA-labeled neurons in cerebral cortex. Electrophysiological properties of subicular VVA-labeled cells were studied in an acutely dissociated neuron preparation. Dissociated cells were labeled in vitro with VVA coupled either to a fluorescent marker or to small beads. The viability of labeled dissociated cells was confirmed, and identified cells were partially characterized electrophysiologically using whole-cell voltage clamp recording. VVA-labeled cells were electrophysiologically similar to pyramidal cells from the same region, except that the VVA-labeled cells showed only small transient outward currents.

Animals↗
PubMed1987

Differential effects of ethanol on photic and acoustic evoked potentials in the reticular formation of rats.

Flash and click evoked potentials were recorded from the same electrode in the midbrain reticular formation of hooded rats. Animals were given i.p. injections of saline, 0.25, 0.5, 1.0 or 2.0 g ethanol/kg body wt. on separate days. The click data demonstrated both a biphasic effect of ethanol and an enhanced sensitivity relative to the flash data. It is suggested that differing evoking stimuli may sample the activity of functionally different populations of neurons within the reticular formation.

Animals↗
PubMed1977

Environmental air and airborne infections.

The results of a study on the epidemiology of airborne (aerobic) surgical infections are presented. The first phase of the study was carried out in a surgical suite which contained no environmental or traffic control systems. The second phase of the study took place within a modern "up to date" operating room suite containing multiple air screens as well as an elaborate ventilation system utilizing HEPA type filters which provided the operating room with clinically sterile air. One hundred and fifty-six patients were also studied. All patients underwent major procedures. The ratio of clean, clean-contaminated, and dirty cases was the same in both groups. Preoperatively, a nasal swab, clean voided urine (or vaginal swab) and a rectal swab were obtained on each patient. Daily nasal cultures and cultures of suspected sites of infection were obtained postoperatively. Daily nasal cultures and "glove sweat" cultures were obtained on all personnel attending the patient. Environmental cultures of the operating room, the operating room hallway, recovery room and patients' rooms were also taken. All samples were checked for the presence of staphylococci, streptococci, Escherichia coli, proteus species, enterobacter, klebsiella, and pseudomonas. In all, 15,000 cultures were taken during the study. The rate of infection was essentially the same in both phases of the study. Environmental air only occasionaly served as the source of infecting organisms. The results of the study support the conclusion that the most common source of infecting organisms in surgical infections is thepatient or those around him. The most common time of contamination is during the surgical procedure itself. Surgical infections can best be minimized by meticulous observation of fundamental principles of antisepsis rather than by dependence on elaborate and costly ventilation and air control systems.

Adolescent↗
PubMedDate not supplied

Detection of vasopressin mRNA in cells of the medial amygdala but not the locus coeruleus by in situ hybridization.

Vasopressin (AVP)-immunoreactive cells have been previously reported in the medial amygdala (AME) and in the locus coeruleus (LC). The present study was designed to verify the presence of AVP-synthesizing neurons in these areas using in situ hybridization histochemistry. A 35S-labelled oligonucleotide probe, complementary to the glycopeptide portion of the vasopressin-encoding mRNA, was used to label cells expressing the AVP gene in brain sections from male Wistar rats. AVP mRNA-positive cells were identified in the AME and were located throughout the anterodorsal and posterodorsal aspect of the nucleus. Cells in the LC, however, did not exhibit labelling for the glycopeptide portion of the AVP gene. The highest density of labelled cells in the medial amygdala occurred 2.30 to 2.80 mm caudal to bregma. The labelling intensity of the cells averaged 53.8 +/- 3.9 grains/cells and was constant throughout the rostro-caudal extent of the AME. These data demonstrate the presence of AVP-synthesizing cells in the AME and provide a method for quantifying their activity. In addition, these data suggest that the cells in the LC may not synthesize vasopressin.

Amygdala↗