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Biomedical subjects

W C Clark

Publications and source records attributed to W C Clark.

At least 73 records · Page 4Linked to original sources
PubMed1982

Use of the carbon dioxide laser in the operative management of intracranial meningiomas: a report of twenty cases.

This study presents 20 cases of meningioma of various intracranial locations, all of which were removed with the carbon dioxide surgical laser system. The carbon dioxide laser is contrasted with other means of meningioma removal to emphasize the advantages of this new technology. These advantages include: (a) the ability to operate with smaller exposures, (b)reduced brain retraction, (c) a reduced amount of mechanical manipulation by vaporizing the tumor mass, (d) vaporization of the dural attachment after the removal of tumor, (e) improved operative precision, and (f) decreased intraoperative significant advancement in the ability to remove meningiomas that might prove difficult to extirpate by conventional means.

Adult↗
PubMed1982

Neuroradiological detection of small and intracanalicular acoustic tumors: an emphasis on CO2 contrast-enhanced computed tomographic cisternography.

Seventy patients suspected clinically of having an acoustic tumor were evaluated using the computed tomographic (CT) scan as the initial neuroradiological procedure, followed by CO2 contrast CT cisternography in cases where the intravenous contrast-enhanced scan did not reveal any lesion. Forty-eight gas CT cisternograms revealed 10 small acoustic tumors, 2 of which were totally intracanalicular. The authors present a review of the basic CT anatomy of the temporal bone as it relates to acoustic tumors. Based upon the ease of performance of the procedure, the low postexamination morbidity, and the excellent diagnostic results, CO2 CT cisternography is recommended as the procedure of choice in the diagnosis of small and intracanalicular acoustic tumors.

Adult↗
PubMed1982

A model of clinical pain. Technique for evaluation of analgesic agents.

A method is described utilizing repetitive electrical stimulation for the production of long-term continuous pain which approaches the quality of clinical pain. This technique provides for on-line monitoring of actual power delivered to the subject. Incremental stimuli of high and low intensities were randomly superimposed on continuous painful background electrical stimulation. Subjects were studied in a triple crossover design with acupuncture, codeine and baseline treatments. Data were evaluated by Sensory Decision Theory (SDT) procedures. The codeine compound significantly raised the response criterion to higher intensity stimuli but did not effect perception of low intensity stimuli, indicating an analgesic but not an anesthetic effect. No significant differences were found between control and acupuncture results for either pain discriminability or pain report criterion. The results are discussed with regard to the physiological effects of electrical stimulation and the merits of this new stimulation technique.

Acupuncture Therapy↗
PubMed1982

Effect of intranasal cocaine on experimental pain in man.

Sixteen healthy male volunteers had 30 mg of cocaine HCI solution or normal saline placebo impregnated in cotton-covered applicators administered intranasally on different days in a double-blind procedure. Ischemic tourniquet pain was significantly less after cocaine than it was in pretreatment control. It was also significantly less than after administration of a placebo. Responses to questionnaires concerning subjective drug effects, mood, and alertness revealed little change in psychological status associated with either cocaine or placebo. Thus, the reported decrease in pain was probably not caused by a change in affect or by altered consciousness. These results indicate that, in addition to its known properties as a local aesthetic, cocaine when applied intranasally exerts an analgesic effect.

Administration, Intranasal↗
PubMed1980

Pain responses in Nepalese porters.

When tested by the method of limits, Nepalese had much higher pain thresholds to electrical stimulation than Occidentals did. Discriminability was the same for both groups, however, indicating that there were no neurosensory differences. Nepalese had higher (stoical) criteria for reporting pain but were not less sensitive to noxious stimulation. The battery of sensory measurement procedures described may be applied to any modality and are particularly applicable to difficult field conditions.

Asian People↗
PubMed1980

Induction of translatable mRNA for dopa decarboxylase in Drosophila: an early response to ecdysterone.

Ecdysteroid titer and dopa decarboxylase (aromatic-L-amino-acid carboxy-lyase, EC 4.1.1.28) activity were determined throughout the life cycle of Drosophila melanogaster. Five peaks in the amount of hormone were observed, which preceeded five dopa decarboxylase peaks by times ranging from 5 to 58 hr. Late in the third instar the hormone and enzyme maxima are nearly coincident. The increase in enzyme activity observed at this time is paralleled by an increase in translatable dopa decarboxylase mRNA. To obtain evidence that ecdysterone induces the appearance of this mRNA we made use of the temperature-sensitive ecd1 mutant. Garen et al. [Garen, A., Kauvar, L. & Lepesant, J.-A. (1977) Proc. Natl, Acad. Sci. USA 74, 5099-5103] have shown that when third instar mutant larvae are kept at 29 degrees C, the ecdysteroid titer remains low. In such larvae we show that the normal increase in dopa decarboxylase activity fails to appear, and no translatable dopa decarboxylase mRNA can be detected. Exogenous feeding of ecdysterone to these larvae results in a rapid synthesis of dopa decarboxylase in the epidermal cells. In addition, a parallel increase in translatable dopa decarboxylase mRNA occurs, which may be a primary response of these target cells to ecdysterone.

Animals↗
PubMed1980

Antagonism of nitrous oxide analgesia by naloxone in man.

The possible reversal of nitrous oxide analgesia by naloxone was investigated. Two studies were conducted in 21 healthy male subjects, who responded to ischemic pain produced by tourniquet applied to the upper arm for 15 min, while breathing air or nitrous oxide, 33 per cent. Using a double-blind procedure, the subjects received intravenous injections of naloxone and saline solution on different days. In eight subjects, naloxone, 8 mg, administered without nitrous oxide, had no effect on pain report. However, unlike saline solution, naloxone, 8 mg, decreased significantly the analgesia induced by nitrous oxide. In 13 subjects, naloxone, 4 mg, also decreased significantly the effect of nitrous oxide analgesia in comparison with saline solution. Naloxone showed its reversal effect mainly on sensory response rating obtained during the painful stages of ischemia, between 11 and 15 min. The results suggest that analgesia induced by nitrous oxide may be partly related to the opiate receptor--endorphin system in man.

Analgesia↗
PubMed1978

New schistorophine nematodes (Acuraiidae) from New Zealand shore birds.

Viktorocara torea and Sciadiocara tarapunga n. spp. are described from specimens from the gizzards of Haematopus ostralegus finschi and Larus novaehollandiae scopulinus respectively. All hosts were collected in the South Island, New Zealand. V. torea is characterised by the possession of doubly bifid apices to the long spicule and absence of a subterminal spicular spur; presence of six preanal papillae, the first and second widely spaced: the muscular region of the oesophagus constituting about one quarter of the total length of the oesophagus. S. tarapunga is similar to S. umbellifera, but differs in having the muscular region of the oesophagus shorter than the glandular region, a more slender body in both sexes, much smaller spicules (78--91 micrometer and 275--359 micrometer) with the right spicule not more than one-third as long as the left one. The long spicule bears a pair of similar, rounded, laterally placed spatulate apices. It is suggested that Sciadiocara umbellifera of previous authors may encompass more than one species.

Animals↗
PubMed1974

Acupunctural analgesia? Evaluation by signal detection theory.

Pain responses to noxious thermal stimulation decreased in the acupunctured arm of subjects as compared to the arm not treated with acupuncture; this result suggested that effective analgesia had been induced. However, sensory decision theory analysis of the data revealed no difference in discriminability. This failure to find a sensory (physiological) change strongly suggests that analgesia had not been induced. The sole effect of acupuncture was to cause the subjects to raise their pain criterion in response to the expectation that acture works.

Acupuncture Therapy↗