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Biomedical subjects

R L Wynn

Publications and source records attributed to R L Wynn.

At least 19 recordsLinked to original sources
PubMed1992

"America responds to AIDS," but did college students? Differences between March, 1987, and September, 1988.

To assess thoughts, perceptions, attitudes, and behavior related to AIDS, data were collected from 2 similar samples of college students. The sets of data were collected 18 months apart. Results indicate increased awareness and knowledge and changed attitudes and behaviors in some cases, but the absolute magnitudes of the differences are small for most between-group comparisons. Also, the evidence suggests that many students lack detailed knowledge and fail to see the implications of their knowledge for change in their own behavior. These findings imply educational efforts must go beyond merely providing knowledge and explicitly link facts to personal belief systems and decision making.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Imipramine-fentanyl antinociception in a rabbit tooth pulp model.

Antinociception of imipramine (I) and its effect in combination with fentanyl (F) was evaluated in rabbits using electrically-induced lick chew responses via tooth pulp stimulation as the model of nociception. Acute i.v. injections of I elicited a graded dose response comparable to i.v. morphine (M) with I ED 50 = 4.35 mg/kg (2.31-8.14, 95% CL) and M ED 50 = 1.81 mg/kg (1.11-3.90), with no differences in the slopes between the two curves. The lethal dose of I was 10 mg/kg. An i.v. dose of I twice the ED 50 elicited an antinociceptive effect of more than 50% maximum possible effect (MPE) for 90 minutes with peak effect of 82% MPE occurring at 15 minutes. These effects of I were not reversed by a morphine-reversal dose of naloxone (0.1 mg/kg i.v.) but were reversed with a ten fold dose of naloxone. F ED 50 values (mcg/kg) were lowered from 11.35 to 2.70, 0.74 and 0.33 with increasing pretreatment doses of I (1.0, 2.1 and 3.2 mg/kg). These magnitudes of potency increases of F were 4.2, 15.3 and 34.4 fold respectively. A single i.v. ED 50 dose of I extended the time to 50% MPE of an ED 90 dose of F from 26 minutes to 77 minutes; of a 2 X ED 50 dose of F from 17 minutes to 28 minutes. Data points for three different combinations of I and F fell significantly within the synergistic field of an ED 50 isobologram and a polynomial equation described the curve best fitting the data points. F alone (i.v. ED 50 dose) increased the PaCO2 values to 74% above controls and three different combinations with I showed no increases in PaCO2 values above controls. I alone did not significantly cause any change in PaCO2 values from controls.

Analgesics↗
PubMed1989

Effects of midazolam on fentanyl antinociception and respiration in a rabbit model.

Clinical antinociception is difficult to assess because of difficulties with controls and the incorporation of bias. The rabbit antinociceptive model is highly sensitive and predictive of analgesia in humans. We found that the combination of midazolam with fentanyl enhanced antinociception compared with fentanyl alone. In addition, with this model there were relatively unimportant increases in respiratory depression.

Analgesics↗
PubMed1989

New 4-(heteroanilido)piperidines, structurally related to the pure opioid agonist fentanyl, with agonist and/or antagonist properties.

A research program based on certain heterocyclic modifications (12-50) of the fentanyl (1) molecule has generated a novel class of opioids. In the mouse hot-plate test, these compounds were weaker analgesics than 1. Two types of antagonists were observed in morphine-treated rabbits: those (e.g., 28) that reversed both respiratory depression and analgesia and those (e.g. 32) that selectively reversed respiratory depression. Evaluation of in vitro binding affinities to rat brain opioid receptors was inconclusive for a common locus of action for the agonist as well as the antagonist component. Further pharmacological evaluation of 32, N-(2-pyrazinyl)-N-(1-phenethyl-4-piperidinyl)-2-furamide, in the rat showed it to be a potent analgesic (ED50 = 0.07 mg/kg, tail-flick test) with little cardiovascular and respiratory depression when compared to fentanyl.

Analgesics, Opioid↗
PubMed1989

Antinociceptive activity of pentamorphone, a 14-beta-aminomorphinone derivative, compared to fentanyl and morphine.

The analgesic potency of pentamorphone, a 14-beta-aminomorphinone derivative, was compared to that of fentanyl and morphine by examining quantal dose-effect curves generated from data obtained in the mouse hot plate, rabbit tooth-pulp, and dog tail clamp tests. Onset and duration of antinociceptive effects were also compared. The ED50 values (mg/kg) were determined in mice for pentamorphone (0.0039), fentanyl (0.016), and morphine (7.3). In the rabbit tooth pulp test the ED50 values were 0.0009 mg/kg for pentamorphone, 0.0074 mg/kg for fentanyl, and 1.1 mg/kg for morphine; in the dog tail clamp test these values were 0.012 mg/kg for pentamorphone and 0.018 mg/kg for fentanyl. Duration of action (defined as the time until response to tooth pulp stimulation declined to 50% of maximum possible effect [MPE]) was 10 min with twice the IV ED50 for pentamorphone in mice. This duration was similar to that of the equipotent dose of fentanyl but much shorter than the duration of an equipotent potent dose of morphine (60 min). The duration in rabbits of the ED98 (IV) dose of pentamorphone was 65 min compared to 35 min for an equipotent dose of fentanyl and 200 min for morphine. Intramuscular doses of pentamorphone had significantly faster onset and shorter duration times than equipotent doses of morphine in both mice and rabbits. Pretreatment with naloxone in mice and rabbits attenuated the development of the antinociceptive effects of pentamorphone. This study shows that pentamorphone is a potent analgesic with a duration of action similar to that of fentanyl.

Analgesics↗
PubMed1985

Gentamycin for prophylaxis of bacterial endocarditis: a review for the dentist.

New guidelines have recommended that gentamicin in combination with ampicillin be used for prophylaxis of bacterial endocarditis in patients with prosthetic heart valves. This article reviews some of the important and practical considerations for its use by the dentist. Gentamicin is an aminoglycoside antibiotic most exclusively reserved for treatment of serious infections caused by gram-negative bacteria in which less toxic antibacterials are ineffective. It has also been shown to be impressive in combination with penicillin in treating high-risk endocarditis patients. All strains of enterococci that are resistant to penicillin plus streptomycin are almost always sensitive to penicillin plus gentamicin. There is minimal absorption into the bloodstream from the gastrointestinal tract after oral administration but rapid absorption after intramuscular injection. Peak serum concentrations appear 30 to 90 minutes after intramuscular injection. The T1/2 is 2 hours, and in normal kidneys 85% to 95% of the drug is excreted within 24 hours by glomerular filtration. Ototoxicity and nephrotoxicity are the most serious toxic effects resulting from gentamicin therapy. The incidence of ototoxicity is about 2%, with affected patients experiencing vestibular effects rather than hearing loss. Nephrotoxicity is usually not seen before the patient has had 5 to 7 days of frequent dosing for treatment of systemic infections; the incidence is 2% to 4%. There are no data to suggest that ototoxicity or nephrotoxicity will occur in the patient given a single intramuscular injection of gentamicin for the prophylaxis of bacterial endocarditis. A single intramuscular or intravenous injection each of ampicillin and gentamicin should provide adequate blood levels for protection in the endocarditis patient for at least 4 to 5 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

The effect of fentanyl on the lick/chew response in rabbits.

Tooth pulp stimulation in the rabbit produces a complex rhythmic lick/chew response (LCR). Because of the effect of fentanyl on the afferent and efferent components of oral function we examined its effect on this response. Intravenous fentanyl attenuates the LCR in a dose dependent manner with the ED50 occurring at 0.1 mg/kg. Concurrently a different response to tooth stimulation appears consisting of a slow, non-rhythmic lateral jaw movement (LJR). The effects of fentanyl on both LCR and LJR are blocked by naloxone (0.1 mg/kg). The dopamine antagonist, chlorpromazine (10 mg/kg iv) also has the same qualitative effect as fentanyl on both responses.

Animals↗
PubMed1976

Nonlinear pharmacokinetic model of intravenous anesthesia.

A nonlinear pharmacokinetic model was constructed to describe the body distribution of intravenous anesthetics, using the physiological modeling approach for drug distribution kinetics. The model considers the physiological parameters of tissue volumes and blood flow rates for the standard four phases of blood, viscera, lean tissue, and adipose tissue and also the associated drug parameters known to influence drug distribution. A simple ramp function having a characteristic time (volume per flow rate) is used to describe the rate of approach to equilibrium conditions for each tissue phase. The model was evaluated for the distribution of methohexital and thiopental by comparing calculated values to experimental drug concentrations taken from the literature. The physiological alteration of obesity also was programmed into the model to evaluate its capability for predicting the influence of body alterations on drug distribution. The results indicated that a preliminary mathematical model of relatively simple design is capable of at least a semiquantitative prediction of intravenous anesthetic drug concentrations in body tissues and has the potential of accounting for differences in drug distribution in the presence of selected physiological alterations.

Adipose Tissue↗
PubMedDate not supplied

IV sedation in pediatric dentistry: an alternative to general anesthesia.

This prospective study was conducted to determine the sedative effects of IV ketamine and fentanyl on vital signs and behavior. Twenty-seven children, classified as ASA I, with a mean age of 34 months, were studied. The dosages of IV ketamine and fentanyl given were 0.5 mg/kg and 0.5 mcg/kg, respectively, approximately every 15-20 min. The pulse rate averaged 125 throughout the case. Blood pressure averaged 112/64. The respiration rate averaged 22 breaths per min. Mean behavior composite scores were 1.9 at the initial examination and 3.3 during treatment. One child vomited during treatment. Post-treatment complications were discomfort in 19% (5), nausea in 22% (6), and vomiting in 15% (4) of the patients. We concluded that IV sedation of precooperative healthy pediatric patients with ketamine, fentanyl, and nitrous oxide/oxygen appears to be a safe and effective sedation modality with minimal side effects when administered and monitored by a qualified anesthetist, offering the practitioner an alternative to general anesthesia.

Anesthesia, Dental↗