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Biomedical subjects

R D Miller

Publications and source records attributed to R D Miller.

At least 91 records · Page 5Linked to original sources
PubMed1995

Public evaluations of unrepresented defendants.

Previous articles have addressed the ethical and legal issues involved when private psychiatrists perform forensic evaluations on criminal defendants before the defendants have access to counsel; but there have been few studies addressing evaluations requested through public facilities and by clinicians other than psychiatrists. The authors present the results of a detailed study of defendants admitted for evaluations of competency to proceed to a forensic inpatient unit in one state, as well as data from a national survey of state forensic facilities. The studies were designed to measure the incidence of unrepresented defendants in a population referred for competency evaluation, as well as to examine the reasons for such occurrences. The data reveal that court-ordered evaluations of unrepresented defendants are rare, but continue to exist.

Commitment of Persons with Psychiatric Disorders↗
PubMed1995

Characterization of daytime sleepiness and psychomotor performance following H1 receptor antagonists.

BACKGROUND: While first generation H1-receptor antagonists are widely used, there are relatively few data describing their comparative effects on subjective daytime sleepiness and psychomotor performance. OBJECTIVE: To compare the effects of first generation H1 receptor antagonists on subjective daytime sleepiness and psychomotor performance. METHODS: We conducted two single-dose, cross-over studies. In the first, we validated our methodology in 18 healthy subjects by examining the response to diphenhydramine (50 mg), terfenadine (60 mg), and placebo. In the second trial, we evaluated the relative effects following diphenhydramine (50 mg), diphenhydramine (25 mg), chlorpheniramine (4 mg), and placebo. Psychomotor tests included choice reaction time, hand steadiness, and a test that divided attention between tracking and reaction time. Introspective drowsiness was measured using a visual analog scale and the Stanford Sleepiness Scale. Assessments were made prior to dosing and at one, three, and five hours after dosing; a 7-hour post-drug assessment was included in the second trial. RESULTS: In the first trial, 50 mg diphenhydramine produced significant impairment relative to placebo in both subjective and objective assessments (P < .05). Responses following terfenadine did not differ from placebo. In the second study, all three regimens produced subjective and objective soporific effects to a significantly greater degree than placebo. For example, significant introspective sleepiness was noted three hours following all three regimens (P < .05) and slower choice reaction times were noted one and three hours after dosing (P < .05). The general rank order of effects was diphenhydramine (50 mg), followed by diphenhydramine (25 mg), followed by chlorpheniramine (4 mg). Significant differences among the three regimens were, for the most part, confined to greater soporific effects from diphenhydramine relative to chlorpheniramine (P < .05). CONCLUSIONS: Taken together, our observations confirm that subjective and objective measures of sleepiness and psychomotor performance occur following single doses of diphenhydramine and chlorpheniramine, but not terfenadine. Differences in soporific effects do exist among regimens of first-generation compounds.

Adolescent↗
PubMed1994

Computed tomographic study of the common cold.

BACKGROUND: Colds are common, but the abnormalities they produce in the nasal passages and sinus cavities have not been well defined. METHODS: We studied healthy adult volunteers with self-diagnosed colds of 48 to 96 hours' duration and obtained the following data: information on symptoms, computed tomographic (CT) studies of the nasal passages and sinuses, mucosal-transport times, measures of nasal-airway resistance, and viral-culture studies. Thirty-one subjects (mean age, 24 years) had complete evaluations, including CT scans, which were read without knowledge of the clinical data. An additional 79 subjects underwent the same evaluations, except the CT scans. RESULTS: Of the 31 subjects with CT scans, 24 (77 percent) had occlusion of the ethmoid infundibulum; 27 (87 percent) had abnormalities of one or both maxillary-sinus cavities; 20 (65 percent) had abnormalities of the ethmoid sinuses; 10 (32 percent) had abnormalities of the frontal sinuses; and 12 (39 percent) had abnormalities of the sphenoid sinuses. Infraorbital air cells were present in 14 subjects (45 percent), and pneumatization of the middle turbinate (concha bullosa) was noted in 11 subjects (35 percent). Also common were engorged turbinates (in 7 subjects) and thickening of the walls of the nasal passages (in 13). After two weeks, the CT studies were repeated in 14 subjects, none of whom received antibiotics. In 11 of these subjects (79 percent) the abnormalities of the infundibula and sinuses had cleared or markedly improved. Nasal-airway resistance was abnormal in 29 (94 percent) and mucosal transport in 19 (61 percent) of the 31 subjects who had CT scans. Rhinovirus was detected in nasal secretions from 24 (27 percent) of 90 subjects. CONCLUSIONS: The common cold is associated with frequent and variable anatomical involvement of the upper airways, including occlusion and abnormalities in the sinus cavities.

Adult↗
PubMed1994

Onset and duration of rocuronium and succinylcholine at the adductor pollicis and laryngeal adductor muscles in anesthetized humans.

BACKGROUND: Rocuronium, a new nondepolarizing muscle relaxant, has a rapid onset of activity and may be suitable as a component of a rapid-sequence induction of anesthesia. We evaluated a range of doses on onset and duration of effect at the larynx and the adductor pollicis and compared these characteristics with those of succinylcholine. METHODS: Forty-eight patients aged 18-70 yr, of ASA physical status 1-3, were randomly allocated to receive succinylcholine (1 mg/kg) or one of three doses of rocuronium (0.4, 0.8, or 1.2 mg/kg) during surgery. Anesthesia was induced and maintained with propofol and fentanyl. The trachea was intubated without the use of muscle relaxants, and the cuff of the endotracheal tube placed between the vocal cords. Neuromuscular transmission was monitored by mechanomyography at the laryngeal adductor and adductor pollicis muscles. Muscular activity was evoked with supramaximal stimuli in a train-of-four sequence every 12 s to the anterior branch of the recurrent laryngeal nerve and the ulner nerve. RESULTS: At the laryngeal adductors, peak effect exceeded 99% in all patients given succinylcholine and in none (0%), five (42%), and ten (83%) of those given rocuronium 0.4, 0.8, and 1.2 mg/kg, respectively. At the adductor pollicis, peak effect exceeded 99% in all study patients except two who received rocuronium 0.4 mg/kg (peak effects 91% and 97%). Onset of effect with succinylcholine was significantly more rapid at the laryngeal adductors (34 +/- 12 s, mean +/- SD) than at the adductor pollicis (56 +/- 15 s); this was true also for rocuronium 0.4 mg/kg (92 +/- 29 s and 155 +/- 40 s for the laryngeal adductors and adductor pollicis, respectively). Onset times were similar at the two muscle groups with rocuronium 0.8 and 1.2 mg.kg-1: 96 +/- 29 and 74 +/- 36 s with 0.8 mg/kg and 54 +/- 30 and 65 +/- 21 s with 1.2 mg/kg at the laryngeal adductors and the adductor pollicis, respectively. CONCLUSIONS: The laryngeal adductors are more resistant to the action of rocuronium than is the adductor pollicis. Consequently, the onset of effect of rocuronium, in doses greater than 0.8 mg/kg, is similar to that of succinylcholine at the adductor pollicis but is significantly delayed compared with that of succinylcholine at the laryngeal adductors.

Adolescent↗
PubMed1994

The effect of hypothermia on adductor pollicis twitch tension during continuous infusion of vecuronium in isoflurane-anesthetized humans.

The effect of total body cooling on force of contraction of the adductor pollicis was determined during a constant rate infusion of vecuronium. Anesthesia was induced with thiopental and maintained with isoflurane/nitrous oxide in eight volunteers (study group) and seven surgical patients (control group). After train-of-four (TOF) stimulation of the ulnar nerve, we measured the amplitude of the first response (T1) in the train and the ratio of the fourth-to-first response (TOF ratio). Vecuronium was then administered as an intravenous (i.v.) bolus, 25 micrograms/kg, followed by continuous i.v. infusion, 25 micrograms.kg-1 x h-1; central body (core) temperature was maintained stable for 60 min, at the end of which T1 and TOF responses were constant. In the study group, core temperature was then reduced (using circulating-water blankets) by a mean of 2.6 degrees C, decreasing the T1 and TOF ratio, respectively, by 19% and 18% per degrees C reduction in adductor pollicis temperature. Normothermia was maintained in the control group for a mean of 111 min, with no significant change in T1 and TOF responses. We conclude that, during a constant-rate infusion of vecuronium, the magnitude of neuromuscular block increases significantly when adductor pollicis temperature decreases secondary to core cooling.

Adult↗
PubMed1994

Mild intraoperative hypothermia does not change the pharmacodynamics (concentration-effect relationship) of vecuronium in humans.

To investigate the effect of mild hypothermia on the neuromuscular junction sensitivity to vecuronium, we determined the pharmacodynamics (concentration-effect relationship) of vecuronium in 10 patients (ASA physical class I or II; age range, 21-46 yr; weight range, 54-104 kg), during isoflurane-nitrous oxide-fentanyl anesthesia. Five were cooled to a mean temperature of 34.4 degrees C and five were maintained normothermic at a mean temperature of 36.8 degrees C. Neuromuscular function was monitored by measuring the evoked mechanical response of the adductor pollicis muscle after supramaximal train-of-four stimulation of the ulnar nerve at the wrist. Vecuronium, 3 micrograms.kg-1.min-1, was infused for 10 min, venous blood sampled for 60 min, and twitch tension and plasma concentration data were used to determine pharmacodynamic variables in each patient. Results for the hypothermic and normothermic groups were compared by Mann-Whitney U-test. There were no differences in any pharmacodynamic variable between the hypothermic and normothermic patients. For the hypothermic and normothermic patients, respectively, steady-state plasma concentrations of vecuronium producing 50% neuromuscular block (Css50) were 73 +/- 13 ng/mL (mean +/- SD) and 79 +/- 31 ng/mL; the rate constants for equilibration of vecuronium between the plasma and the neuromuscular junction (Keo) were 0.27 +/- 0.14 per min-1 and 0.26 +/- 0.11 per min, and the power functions representing the slope of the concentration-effect relationship (gamma) were 5.7 +/- 1.9 and 4.4 +/- 1.8.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Psychiatric stigma in correctional facilities.

While legislatively sanctioned discrimination against the mentally ill in general society has largely disappeared, it persists in correctional systems where inmates are denied earn-time reductions in sentences, parole opportunities, placement in less restrictive facilities, and opportunities to participate in sentence-reducing programs because of their status as psychiatric patients or their need for psychotropic medications. The authors discuss the prevalence of such problems from detailed examinations of several correctional systems and from the results of a national survey of correctional medical directors.

Civil Rights↗
PubMed1994

Mental health screening and evaluation within prisons.

Current national standards and/or guidelines for correctional mental health care programs emphasize the importance of various levels of mental health screening and evaluation that should be performed by qualified personnel on all inmates as part of the admission process to a prison. The authors describe the results of a study that included data from all 50 state departments of corrections regarding prison mental health screening and evaluation models. The vast majority of states appear to have adopted some variation of the most recognized guidelines and/or standards (e.g., American Psychiatric Association, National Commission on Correctional Health Care, American Public Health Association) concerning correctional health care systems. Results are also provided concerning the use of standardized psychological tests and informed consent issues.

Expert Testimony↗
PubMed1994

The contribution of muscle relaxants to the advancement of anaesthetic practice: what is required of new compounds?

The introduction of each new muscle relaxant has advanced anaesthetic practice by trying to meet some perceived deficiency in the existing therapeutic armamentarium. Anaesthesiologists need agents which are appropriate to the duration of surgery: they prefer agents which are not subject to drug interaction, have no effect on cardiovascular function, which do not depend significantly on renal excretion, which are easy to reverse, and which have a rapid onset of action. In certain circumstances one of these requirements becomes overridingly important. The latest new addition, rocuronium, fills the gap for an agent with rapid onset while lacking the potentially adverse features of suxamethonium, retaining a medium duration of action and meeting the other requirements set out above as well as any existing agent.

Androstanols↗
PubMed1994

The pharmacodynamics and pharmacokinetics of the metabolite 3-desacetylvecuronium (ORG 7268) and its parent compound, vecuronium, in human volunteers.

The pharmacology of 3-desacetylvecuronium, the principal metabolite of vecuronium, was investigated. We studied 12 healthy volunteers, each on two occasions. First they received 3-desacetylvecuronium alone and then, on a later occasion, vecuronium. Six subjects received a large dose of each drug (pharmacokinetic study), the remaining six received a small dose (pharmacodynamic study). Drug concentrations in plasma and urine were measured using capillary gas chromatography. Neuromuscular block was assessed by measuring force of contraction of the adductor pollicis. Drug plasma concentration vs. time and neuromuscular effect data were analyzed by nonlinear mixed-effects modeling. 3-Desacetylvecuronium, compared with vecuronium (median, range in parentheses), had a smaller plasma clearance, 3.51 (2.11-6.57) vs. 5.39 (5.04-7.19) ml.kg-1.min-1; a larger steady-state distribution volume, 254 (215-410) vs. 152 (111-170) ml.kg-1; a longer terminal elimination half-life 116 (44-672) vs. 34 (25-61) min and a longer mean residence time, 67 (42-145) vs. 26 (18-32) min (P < .05). Renal clearances of 3-desacetylvecuronium and vecuronium were 0.85 (0.15-1.24) and 0.58 (0.16-0.66) ml.kg-1.min-1, respectively (P < .05). Conversion to 3-desacetylvecuronium accounted for 12% of vecuronium's clearance. Concentrations of 3-desacetylvecuronium and vecuronium that produced 50% neuromuscular block were 123 (109-154) and 102 (71-123) ng.ml-1, respectively (P < .05). 3-Desacetylvecuronium is a potent neuromuscular blocking drug and may be responsible for episodes of prolonged paralysis after long-term administration of vecuronium to patients in intensive care units.

Adolescent↗
PubMed1993

A highly polymorphic microsatellite in the class II Eb gene allows tracing of major histocompatibility complex evolution in mouse.

A hallmark of major histocompatibility complex (MHC) genes is their extraordinarily high level of polymorphism. Polymorphic residues on MHC molecules determine which peptide ligands they bind and present to effector T lymphocytes. Although the genetic mechanisms responsible for MHC polymorphism have been delineated, the timetable and the pathway of their diversification remain unclear. To trace MHC evolution, we have characterized a highly polymorphic microsatellite containing tandem repeats (TRs) of two tetranucleotide units, TGGA and GGCA, located at the 3' end of the second intron in the class II Eb gene of mouse. On the basis of length as well as sequence variations, 11 TR alleles were defined in 55 inbred mouse strains, which included MHC recombinant haplotypes and haplotypes derived from different subspecies of mouse. In this extensive sampling, a striking concordance was observed between the serologically identified class II proteins and the associated TR alleles. Examination of several strains carrying the same MHC haplotypes as well as strains carrying recombinant MHC haplotypes indicates that TR alleles are extremely stable. These observations suggest that TR polymorphism predates the separation of various subspecies of mouse. On the basis of sequence divergence, a genealogical tree has been constructed to depict evolution of the different TR alleles. Finally, evidence is presented that suggests this microsatellite polymorphism is generated by slipped-strand mispairing during DNA replication.

Alleles↗
PubMed1993

The mouse severe combined immune deficiency (scid) mutation is closely linked to the B-cell-specific developmental genes VpreB and lambda 5.

The mouse severe combined immune deficiency (scid) phenotype is due to a recessive, autosomal mutation which results in failed development of lymphocytes. An important step during normal lymphocyte development is the germline rearrangement of DNA segments to assemble functional immunoglobulin or T cell receptor genes. scid lymphocytes fail to rearrange these genes properly, resulting in the absence of mature B and T lymphocytes. This mutation was originally mapped to chromosome 16 by linkage to the immunoglobulin lambda light chain genes (Igl-1) and the coat color mutation mahoganoid. We have typed 288 progeny from backcrosses between MOLF/Ei or CAST/Ei and C.B-17-scid for the scid phenotype and nine other loci mapped to the centromeric region of MMU16. We have established a refined map of this region which places the scid gene between Prm-2 and Igl-1. In addition, no recombinations were found between scid and three other loci, VpreB, lambda 5, and D16Mit31, providing markers useful for isolating the scid gene by positional cloning.

Animals↗
PubMed1993

An algorithm for measurement of expiratory flow rate parameters on the partial expiratory flow-volume curve.

Partial expiratory flow-volume (PEFV) curves are a useful tool in airway challenge studies, but unlike the maximal expiratory flow-volume (MEFV) curve, lung function parameters require manual calculation from the flow-volume tracing. We describe an algorithm written in QuickBASIC that analyzes a PEFV curve superimposed on a MEFV curve by (1) identifying the PEFV curve, (2) locating the maximal expiratory flow at the point on the PEFV curve that corresponds to 60% of the baseline forced vital capacity (FVC) below total lung capacity (TLC), termed MEF40%(P), and (3) identifying the size of the PEFV curve along the TLC axis. A report of these parameters is also provided. This algorithm was validated using flow-volume curves from a clinical study in which eight subjects performed two sets of MEFV and PEFV curves separated by approximately 1 hr. Paired comparison of MEF40%(P) determined by the algorithm and two independent manual calculations correlated strongly and yielded no statistically significant differences between the two methods. We conclude that this algorithm provides rapid and accurate determinations of PEFV parameters.

Algorithms↗
PubMed1993

Electro-orientation of ellipsoidal erythrocytes. Theory and experiment.

The frequency-dependent orientation of human and llama erythrocytes suspended in isotonic solutions and subjected to linearly polarized electric fields is examined. Human erythrocytes may be represented as oblate spheroids (3.9:3.9:1.1 microns) with two distinguishable orientations, while the llama cells are approximated as ellipsoids with three distinct axes (4.0:2.0:1.1 microns). Under appropriate experimental conditions, both orientations of the human cells and all three orientations of the llama cells are observed. A theoretical cell model which accounts for the membrane as a thin confocal layer of ideal capacitance is used to predict the orientational spectra. The predicted spectra compare favorably in frequency range and orientational sequence with experimental data. Estimates for cell internal conductivity and permittivity are obtained by adjusting the values of these important parameters to achieve the closet fit of the theoretical curves to the data. By the use of this method, the internal conductivity of llama erythrocytes is estimated to be 0.26 S/m (+/- 20%), while the effective internal dielectric constant and conductivity of Euglena gracilis are estimated to be 120 (+/- 10%) and 0.43 S/m (+/- 20%), respectively.

Animals↗