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Biomedical subjects

R D Miller

Publications and source records attributed to R D Miller.

At least 217 records · Page 12Linked to original sources
PubMed1986

Refining the priming principle for vecuronium during rapid-sequence induction of anesthesia.

Administration of a subparalyzing dose of a nondepolarizing muscle relaxant (priming dose) prior to its intubating dose hastens the onset time (time from muscle relaxant administration to 100% depression of twitch tension) of neuromuscular blockade. This study was undertaken to determine the optimal priming and intubating doses and time interval between these doses (priming interval) of vecuronium during rapid-sequence induction of anesthesia. The authors measured single-twitch tension in 79 healthy, awake, premedicated (fentanyl, 50-150 mu iv, and/or diazepam, 5-10 mg iv) patients. In Part A of the study, the priming dose was varied (0.0, 0.005, 0.01, 0.0015, or 0.02 mg/kg iv). Decrement of twitch tension and symptoms were recorded 3 min later. Four minutes after the priming dose, thiopental, 4-6 mg/kg iv, and vecuronium, 0.1 mg/kg iv, were given. Onset times for the 0.01, 0.015, and 0.02 mg/kg groups were significantly shorter than for 0.005 and 0.0 mg/kg groups. No breathing difficulties were encountered in any of the groups. Decrement of twitch tension greater than 25% of control only occurred in the 0.02 mg/kg group (4 of 11 patients). In Part B, the priming interval was varied (2, 4, or 6 min) after giving the optimal priming dose (0.01 mg/kg). Anesthesia was induced as in Part A. Onset times for the 4-min group were significantly faster than the 2- or 6-min groups. In Part C, the intubating dose was varied (0.07, 0.1, or 0.15 mg/kg iv) after the optimal priming dose and optimal priming interval (4 min). Onset times for the 0.1 mg/kg and 0.15 mg/kg groups were significantly faster than the 0.07 mg/kg group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Neostigmine and edrophonium antagonism of varying intensity neuromuscular blockade induced by atracurium, pancuronium, or vecuronium.

To compare the time course of neostigmine and edrophonium antagonism of varying intensity neuromuscular blockade induced by atracurium, pancuronium, or vecuronium, the authors studied 98 patients anesthetized with nitrous oxide (60%) and halothane or enflurane. Neuromuscular blockade, as monitored by single stimulus-induced twitch tension (TT), was antagonized at varying degrees of spontaneous recovery (2-80% of control TT). Time to antagonism (time from injection of neostigmine or edrophonium to 90% recovery of control TT) was not different between edrophonium, 0.5 mg/kg, and neostigmine, 0.04 mg/kg, when spontaneous recovery had been allowed to occur to at least 11% of control TT prior to antagonist administration (P greater than 0.05). For profound neuromuscular blockade (TT less than or equal to 10% of control) induced by pancuronium or vecuronium, time (mean +/- SD) to antagonism with neostigmine, 0.04 mg/kg, was 7.0 +/- 2.2 min and 5.6 +/- 1.7 min, respectively, while the same for edrophonium, 0.5 mg/kg, was 20.0 +/- 8.0 min and 15.0 +/- 12.5 min, respectively (P less than 0.05). Time to antagonism of profound atracurium-induced neuromuscular blockade was 8.5 +/- 3.3 min for neostigmine, 0.04 mg/kg, and 9.8 +/- 7.0 min for edrophonium, 0.5 mg/kg, (P less than 0.05). For profound vecuronium-and pancuronium-induced neuromuscular blockade, time to antagonism by edrophonium, 1.0 mg/kg, was 4.6 +/- 3.0 min and 3.9 +/- 1.6 min respectively. The authors conclude that neostigmine, 0.04 mg/kg, antagonizes neuromuscular blockade within 12 min when TT is greater than 2% of control at time of reversal. When TT is greater than 10% of control, edrophonium, 0.5 mg/kg, produces similar time to antagonism.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1986

Pharmacology of laudanosine in dogs.

The authors determined the pharmacokinetics (including transfer into cerebrospinal fluid [CSF]) and the cardiovascular and central nervous system (CNS) effects of laudanosine, a metabolite of atracurium. Eight dogs were anesthetized with halothane; blood pressure and a fronto-occipital electroencephalographic lead were monitored. Laudanosine (1 mg . kg-1 iv) was administered as a bolus, and its concentrations in plasma, CSF, urine, and bile were determined by liquid chromatography. Three-compartment modeling of plasma laudanosine concentrations yielded an elimination half-life for laudanosine of 113 +/- 24 min (mean +/- SD) and a clearance of 25 +/- 8 ml . kg-1 . min-1. CSF concentrations of laudanosine were highest 5-10 min after iv injection of laudanosine and ranged in concentration from 208 to 572 ng . ml-1 (i.e., 36-87% of the corresponding plasma concentrations). Unchanged laudanosine was found in urine (0.5-12% of injected dose) and bile (less than 0.1%); metabolites of laudanosine were found in both fluids. After a 6-h sampling period, dogs were hyperventilated with halothane (FIO2 = 0.2) to a PaCO2 of 26-28 mmHg. Laudanosine was then administered 2 mg . kg-1 iv every 5 min. With cumulative doses of 2-8 mg . kg-1, all dogs showed signs of "awakening" from anesthesia. Cumulative doses of 14-22 mg . kg-1 produced seizure activity in all animals. Mean arterial blood pressure decreased significantly to 86% of control levels at 1 min following administration of laudanosine (1 mg . kg-1 iv) and returned to control levels 4 min later.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1986

An assessment of the Newcastle Anxiety Depression Index.

The Newcastle Anxiety and Depression Diagnostic Index (NADDI) has been reviewed, and its advantages and disadvantages discussed. One hundred eighty-seven patients were examined, and grouped into three categories by means of the NADDI, which produced a unimodal distribution of score. These three groups were studied in respect of the Hamilton Depression and SCL-90 self-rating scales. Significant profile differences were found on both scales. Patients with pure anxiety and pure depression were more distressed than the intermediate group of mixed anxiety-depressed patients. The NADDI scale items were compared in four clinical groups of primary endogenous, primary nonendogenous depression, generalized anxiety, and panic disorder. Most differences were found when panic disorder was compared to the other three groups, and generalized anxiety disorder received minimal validation. Treatment response was also examined.

Adult↗
PubMed1986

Effect of oral contraceptives on leukocyte phagocytic activity and plasma levels of prostaglandin E2 and thromboxane B2 in normal menstruating women.

Mononuclear and polymorphonuclear cells were isolated from the peripheral blood of normal menstruating women. Four of the subjects were not using oral contraceptives and five were taking various formulations. The women were tested once a week for 12 consecutive weeks. Plasma levels of 6-keto-prostaglandin F2 alpha (6-KF), prostaglandin E2 (PGE2), thromboxane B2 (TxB2), estrogen, and progesterone were measured by specific radioimmunoassays. The phagocytic activity of the mononuclear and polymorphonuclear cells isolated from the peripheral blood was measured with a bacterial phagocytosis and killing assay. The phagocytic activity of both types of cells was depressed perimenstrually in both groups of women. However, examination of individuals showed that those subjects not taking oral contraceptives had a worsening of phagocytic activities with approaching menses while the oral contraceptive subjects generally had an improving of these activities at this time. We were unable to correlate the phagocytic activities with either hormone or prostaglandin levels in the plasma of these subjects. However, the subjects on oral contraceptives had significantly lower levels of PGE2 and TxB2 than those women who were not using oral contraceptives.

Contraceptives, Oral↗
PubMed1986

Bactericidal effect of lactoferrin on Legionella pneumophila.

Lactoferrin, an iron-binding protein found in mucosal secretions and in specific granules of polymorphonuclear leukocytes, has been shown to be bactericidal for a variety of organisms. In this study, the effect of lactoferrin on Legionella pneumophila was investigated. Purified human apolactoferrin was bactericidal for the Knoxville 1 strain (serogroup 1), with a 4-log decrease in viability within 2 h at 37 degrees C. Killing was dependent on the iron-free state since iron-saturated lactoferrin had no activity. Guinea pig passage of this strain did not affect its sensitivity to lactoferrin. Treatment of the cells with dilutions of the lactoferrin resulted in correspondingly reduced killing. Activity was temperature dependent; there was no loss of viability at 1 or 22 degrees C and slightly enhanced killing at 41 degrees C. Addition of Mg2+ blocked bactericidal activity. In addition, mature human milk, a lactoferrin-containing mucosal secretion, was also bactericidal for L. pneumophila. As demonstrated with the purified lactoferrin, bactericidal activity was lost when the milk was iron saturated.

Animals↗
PubMed1986

An integrated model for the interaction of muscle relaxants with their antagonists.

An integrated model describing the interaction of nondepolarizing neuromuscular blocking agents with reversible anticholinesterase agents is derived and compared with a naive model using experimental data obtained from four anesthetized dogs. Three consecutive but separate steady-state d-tubocurarine blocks (approximately 50, 70, and 90%) were induced in each of the four dogs and reversed by short edrophonium infusions. Edrophonium arterial concentrations and twitch tension of the anterior tibialis muscle were measured. Both the integrated and the naive model were fit to the twitch tension data using a model with a hypothetical "effect" compartment. The integrated model consistently fit the twitch tension data better than the naive model; the sum of squared deviations was lower by 46, 45, 87, and 69%, respectively, with the integrated model than with the naive model. Also, in contrast to the naive model, the integrated model is capable of describing the interaction of the anticholinesterase agent and the neuromuscular blocking agent when the concentration of either varies with time.

Animals↗
PubMed1986

Higher risk of lung cancer in chronic obstructive pulmonary disease. A prospective, matched, controlled study.

To assess the risk of lung cancer in patients with chronic obstructive pulmonary disease, we matched, on the basis of age, sex, occupation, and smoking history, 113 persons ("cases") who had a forced expiratory volume in 1 second (FEV1) of 70% or less of predicted normal with 113 control persons who had an FEV1 of 85% or more. All persons were observed from 1973-74 through 1984 for a diagnosis of lung cancer, death from lung cancer, and death from any cause. At entry, subjects had an age range of 45 to 59 years; men numbered 186 and women 40. Histologically proven lung cancer developed in 9 cases and in 2 controls, all men. The rate of development of lung cancer was significantly different in the two groups (p = 0.024): the 10-year cumulative percentage was 8.8% for cases and 2.0% for controls. Overall 10-year survival was estimated to be 74.0% for cases and 91.1% for controls (p less than 0.001).

Female↗
PubMed1986

Elimination of atracurium in humans: contribution of Hofmann elimination and ester hydrolysis versus organ-based elimination.

Atracurium, a nondepolarizing muscle relaxant, is eliminated through several pathways, including Hofmann elimination (spontaneous degradation in plasma and tissue at normal body pH and temperature) and ester hydrolysis (catalysis by nonspecific esterases). Because elimination of atracurium occurs in both tissue and plasma, traditional pharmacokinetic models assuming elimination from a single central compartment are inaccurate for atracurium. The authors developed a two-compartment pharmacokinetic model in which hepatic and/or renal elimination occurs from the central compartment (Cl organ), and Hofmann elimination and ester hydrolysis occur from both central and peripheral compartments (Cl nonorgan). To determine the in vitro rate constant for Hofmann elimination and ester hydrolysis, atracurium was added to whole blood kept at each patient's pH and temperature. The values for this rate constant ranged from 0.0193 to 0.0238 per min. When these values were applied to the pharmacokinetic model, Cl total, Cl organ, and Cl nonorgan were 4.8 +/- 1.1, 3.0 +/- 0.9, and 1.9 +/- 0.6 ml . kg-1 . min-1, respectively. The authors conclude that more than one-half of the clearance of atracurium occurs via pathways other than Hofmann elimination and ester hydrolysis.

Adult↗
PubMed1985

The Munchausen patient in a forensic facility.

The many reports in the literature of chronic factitious illness (Munchausen's Syndrome) have emphasized the difficulty of treating these patients because of their propensity to leave medical facilities as soon as the factitious nature of their symptoms is discovered, and because of their disinclination to accept psychiatric help. The authors report on their treatment of such a patient who was incarcerated for over ten years under a criminal commitment, and discuss methods for overcoming resistances to treatment in Munchausen's patients.

Adult↗
PubMed1985

Monoclonal antibodies to different epitopes in amelogenins from fetal bovine teeth recognize high-molecular-weight components.

Enamel proteins were extracted and partitioned into amelogenin and enamelin fractions. Although several attempts were made to raise monoclonal antibodies to each protein fraction, monoclonal antibodies were only obtained against the amelogenin fraction. Six monoclonal antibodies were generated, and these could be classified into three groups recognizing different epitopes by a competitive enzyme-linked immuno-absorbent assay. A model for the arrangement of the epitopes is proposed. In Western-blotting experiments, all six monoclonal antibodies recognized amelogenin components of approx. 45,000 and 60,000 daltons as well as lower molecular-weight components of 10,000 to 30,000. It is proposed that the 45,000 and 60,000 dalton components are precursors of the lower molecular-weight components.

Amelogenin↗
PubMed1985

Sulbactam kinetics and excretion into breast milk in postpartum women.

We gave intravenous infusions of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin or cephalothin to women 2 days after cesarean section delivery. The elimination t1/2 was 1.0 hours, the volume of distribution at steady state was 268 ml/kg, and renal clearance was 295 ml/min. These values are similar to those in normal young men and in surgical patients and suggest that dose regimens of sulbactam will not need adjustment in the postpartum period. Sulbactam concentrations in breast milk averaged 0.5 micrograms/ml, a value similar to that of several beta-lactam antibiotics.

Ampicillin↗
PubMed1985

Vecuronium kinetics and dynamics in anesthetized infants and children.

Vecuronium kinetics and dynamics were determined in five infants (3 to 11 months old) and five children (1 to 5 years old) during anesthesia with 70% nitrous oxide and 0.9 MAC halothane. Vecuronium was infused intravenously at a rate of 2.5 micrograms/kg/min while twitch tension of the adductor pollicis muscle was recorded and venous blood samples were drawn for determination of vecuronium concentrations by mass spectrometry. The elimination t1/2 was determined by linear regression of the log postdistribution concentration-time data; these values and noncompartmental techniques were used to calculate total plasma clearance (Cl), volume of distribution at steady state (Vdss), and mean residence time. The steady-state plasma concentration resulting in 50% depression of twitch tension (Cpss50) was determined by an effect compartment and a sigmoid concentration vs. paralysis model. Vdss was larger in infants (357 +/- 70 ml/kg; mean +/- SD) than in children (204 +/- 116 ml/kg), and Cl was of the same order for infants and children (5.6 +/- 1.0 and 5.9 +/- 2.4 ml/kg/min). Mean residence time was longer in infants (66.3 +/- 22.9 minutes) than in children (34.3 +/- 8.0 minutes). Cpss50 was lower in infants (57 +/- 18 ng/ml) than in children (110 +/- 28 ng/ml). The quantity of vecuronium in the body at steady state at 50% depression of twitch tension (Vdss X Cpss50) was similar in infants and children (21.2 +/- 9.9 and 19.0 +/- 3.3 micrograms/kg). During comparable nitrous oxide-halothane anesthesia, age-related changes in Vdss, Cl, and Cpss50 were much like those found for d-tubocurarine.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1985

Effect of renal failure on laudanosine excretion in man.

Patients with renal failure and undergoing a cadaver renal transplant were found to have plasma concentrations of laudanosine, following the administration of a single bolus dose of atracurium 0.5 mg kg-1, higher than those found in patients without renal failure. Since laudanosine is a known central nervous system stimulant in a variety of animal species, its actions should be investigated further in man, and particularly in patients with renal failure.

Atracurium↗
PubMed1985

Joint distribution of insertion elements IS4 and IS5 in natural isolates of Escherichia coli.

A reference collection of natural isolates of Escherichia coli has been studied in order to determine the distribution, abundance and joint occurrence of DNA insertion elements IS4 and IS5. Among these isolates, 36% were found to contain IS4 and 30% were found to contain IS5. Among strains containing IS4 the mean number of copies per strain was 4.4 +/- 0.8; the comparable figure for IS5 was 3.7 +/- 1.0. Although the presence of the elements among the isolates was independent, among those isolates containing both IS4 and IS5, there was a significant negative correlation in the number of copies of the elements. The reference collection was also studied for the presence of the DNA sequences flanking the single copy of IS4 in the chromosome of E. coli K12. Homologous sequences were found in only 26% of the isolates. The sequences flanking the IS4 invariably occur together, and their presence is significantly correlated with the presence of IS4. In eight of the strains that carry these flanking sequences, an IS4 is located between them, and the sequences are present at the homologous position as in the K12 strain. We suggest that IS4 and its flanking sequences share a common mechanism of dissemination, such as plasmids, and we present evidence that they are included in a much larger transposable element.

Base Composition↗