Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies

Assessment of strategies for engineering controls for the prevention of airborne infectious disease transmission to patients and to health care and related workers requires consideration of the factors relevant to aerosol characterization. These factors include aerosol generation, particle size and concentrations, organism viability, infectivity and virulence, airflow and climate, and environmental sampling and analysis. The major focus on attention to engineering controls comes from recent increases in tuberculosis, particularly the multidrug-resistant varieties in the general hospital population, the severely immunocompromised, and those in at-risk and confined environments such as prisons, long-term care facilities, and shelters for the homeless. Many workers are in close contact with persons who have active, undiagnosed, or insufficiently treated tuberculosis. Additionally, patients and health care workers may be exposed to a variety of pathogenic human viruses, opportunistic fungi, and bacteria. This report therefore focuses on the nature of infectious aerosol transmission in an attempt to determine which factors can be systematically addressed to result in proven, applied engineering approaches to the control of infectious aerosols in hospital and health care facility environments. The infectious aerosols of consideration are those that are generated as particles of respirable size by both human and environmental sources and that have the capability of remaining viable and airborne for extended periods in the indoor environment. This definition precludes skin and mucous membrane exposures occurring from splashes (rather than true aerosols) of blood or body fluids containing infectious disease agents. There are no epidemiologic or laboratory studies documenting the transmission of bloodborne virus by way of aerosols.

Molecular instability in the COII-tRNA(Lys) intergenic region of the human mitochondrial genome: multiple origins of the 9-bp deletion and heteroplasmy for expanded repeats

We have identified two individuals from Glasgow in Scotland who have a deletion of one of two copies of the intergenic 9-bp sequence motif CCCCCTCTA, located between the cytochrome oxidase II (COII) and lysine tRNA (tRNA(Lys)) genes of the human mitochondrial genome. Although this polymorphism is common in Africa and Asia, it has not been reported in Northern Europe. Analysis of the mitochondrial DNA control region sequences of these two individuals suggests that they belong to a lineage that originated independently of the previously characterized African and Asian 9-bp deleted lineages. Among the Scottish population we have also identified a maternal lineage of three generations exhibiting heteroplasmy for two, three and four copies of the CCCCCTCTA motif. Polymerase chain reaction amplification across the COII-tRNA(Lys) intergenic region of these individuals gives different ratios of the three product lengths that are dependent on the concentration of the DNA-binding dye crystal violet. To investigate whether changes in repeat number were generated de novo, we constructed clones containing known numbers of the CCCCCTCTA motif. In the presence of high concentrations of crystal violet we obtained two, three and four copies of this motif when the amplification template contained only four copies. Various DNA-binding drugs are known to stabilize bulged structures in DNA and contribute to the process of slipped-strand mispairing during DNA replication. These results suggest that the COII-tRNA(Lys) intergenic region is unstable owing to slipped-strand mispairing. Although sequences containing four copies of the CCCCCTCTA motif are less stable in vitro, we observed an increase in the proportion of mitochondrial genomes with four repeats between-a mother and a daughter in the heteroplasmic lineage. From this we conclude that drift in the germ-line lineage is a main factor in the maintenance or loss of heteroplasmy.

16 alpha-substituted analogs of the antiprogestin RU486 induce a unique conformation in the human progesterone receptor resulting in mixed agonist activity

Previously, we have shown that agonists and antagonists interact with distinct, though overlapping regions within the human progesterone receptor (hPR) resulting in the formation of structurally different complexes. Thus, a link was established between the structure of a ligand-receptor complex and biological activity. In this study, we have utilized a series of in vitro assays with which to study hPR pharmacology and have identified a third class of hPR ligands that induce a receptor conformation which is distinct from that induced by agonists or antagonists. Importantly, when assayed on PR-responsive target genes these compounds were shown to exhibit partial agonist activity; an activity that was influenced by cell context. Thus, as has been shown previously for estrogen receptor, the overall structure of the ligand-receptor complex is influenced by the nature of the ligand. It appears, therefore, that the observed differences in the activity of some PR and estrogen receptor ligands reflect the ability of the cellular transcription machinery to discriminate between the structurally different complexes that result following ligand interaction. These data support the increasingly favored hypothesis that different ligands can interact with different regions within the hormone binding domains of steroid hormone receptors resulting in different biologies.

Structure-activity studies of 2,3,4,4a,5,9b-hexahydroindeno[1,2-c]pyridines as antispermatogenic agents for male contraception

Analogs of (4aRS,5SR,9bRS)-2-ethyl-2,3,4,4a,5,9b-hexahydro-7-meth yl-5-p- tolyl-1H-indeno[1,2-c]pyridine (Sandoz 20-438, 10a; R1 = ethyl, R2 = R3 = methyl, R4 = H) have been synthesized and tested in mice for their ability to reduce testes weight and disrupt spermatogenesis. The activity was strongly dependent on stereoisomerism and chirality, consistent with a mechanism of action involving interaction with a specific macromolecule. It was affected by changes in the nitrogen substituent and most strikingly by changes in the p-substituent of the 5-aryl ring. A hydrogen, fluorine, hydroxy, or methoxy substituent led to loss of activity, whereas methyl (Sandoz 20-438, 10a), carboxylate (RTI-4587-054, 10k; R1 = ethyl, R2 = methyl, R3 = COOH, R4 = H), ester (RTI-4587-056, 12b; R1 = ethyl, R2 = methyl, R3 = COOMe, R4 = H), formyl (RTI-4587-030, 12i; R1 = ethyl, R2 = methyl, R3 = CHO, R4 = H), or hydroxymethyl (RTI-4587-055, 12g; R1 = ethyl, R2 = methyl, R3 = CH2OH, R4 = H) groups resulted in antispermatogenic compounds. Methyl ester 12b was an effective antifertility agent, without apparent effects on mating, when given orally to male mice at 7-15 mg/kg daily for 35 days. Further evaluation of these compounds as male contraceptive agents and probes for study of spermatogenesis appears warranted.

Comparison in humans of the potency and pharmacokinetics of intravenously injected cocaethylene and cocaine

Cocaethylene (the ethyl ester of benzoylecgonine) is a product of the interaction between ethanol and cocaine. The results of preclinical studies and of a pilot clinical study have shown cocaethylene to produce pharmacologic effects similar to those of cocaine. However, no information is available concerning the potency and pharmacokinetics of cocaethylene in comparison to those of cocaine in humans. We report the results of a single-blind, crossover study in which six male, healthy, paid volunteers, who were moderate users of cocaine, were intravenously injected with the water soluble fumarate salt of cocaethylene (0.25 mg/kg cocaethylene base) or an equivalent dose of the water soluble hydrochloride salt of cocaine (0.25 mg/kg cocaine base). Each dose was dissolved in normal saline and injected over a 1-min interval. Test sessions were separated by a 1-week interval. The variables measured were: cocaine and cocaethylene plasma concentrations, subjective and cardiovascular effects. The results indicate, that in comparison to cocaine, cocaethylene had a significant smaller elimination rate constant (0.42 versus 0.67 l/h), had a longer elimination half-life (1.68 versus 1.07 h), and induced ratings of "high" and changes in heart rate that were of lower magnitude (65%, and 43%, respectively). During the period of time that pharmacologic effects were present the plasma concentrations of cocaine and cocaethylene were statistically indistinguishable. This finding supports the conclusion that in humans cocaethylene is less potent than cocaine.

A method for avoiding mis-priming when sequencing with Dynabeads

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Effects of D-ring substituents on antiprogestational (antagonist) and progestational (agonist) activity of 11 beta-aryl steroids

The discovery of antiprogestational steroids by the Roussel-Uclaf group not only was a major scientific advance but also opened the way to new methods of fertility control and new therapies for such conditions as cancer. RU486, the prototype of the series, is distinguished by a p-(N,N-dimethylaminophenyl) substituent at the 11 beta- position of the steroid framework, a 4,9-dien-3-one system and 17 beta-hydroxy-17 alpha-propynyl substituents. We examined the effect of varying the 17 alpha- substituent in 17 beta-hydroxy compounds analogous to RU486, the effect of introducing a progesterone side chain at C-17, and the effects of further substitution at C-17 alpha and C-16 alpha on the activity of these latter compounds. These studies indicate an important role for D-ring substituents in determining the balance of agonist/antagonist activity in this series. For example, 17 alpha-acetoxy-17 beta-acetyl substitution gave a potent antagonist, whereas 16 alpha-ethyl-17 beta-acetyl substitution resulted in a compound with potent progestational (agonist) activity. The compounds present opportunities for further interesting and useful biological investigations.

Determination of l-alpha-acetylmethadol, l-alpha-noracetylmethadol and l-alpha-dinoracetylmethadol in plasma by gas chromatography-mass spectrometry

A method is described for the simultaneous determination of l-alpha-acetylmethadol (LAAM) and its N-demethylated metabolites, l-alpha-noracetylmethadol (norLAAM) and l-alpha-dinoracetylmethadol (dinorLAAM), in plasma by gas chromatography-chemical ionization mass spectrometry. Deuterated internal standards for each analyte serve as carriers and control for recovery during sample purification on a solid-phase extraction column (C18), and subsequent separation and analysis on a DB-17 capillary column. With this method, we have determined levels of LAAM, norLAAM, and dinorLAAM in small volumes of plasma (100 microliters). The limit of quantitation for all analytes was approximately 1.0 ng/g plasma and the limit of detection was approximately 0.5 ng/g plasma. An experimental application is also described where these analytes are quantitated in plasma obtained from rats before, during, and after chronic administration of LAAM-HCl. Since this technique affords a selective and sensitive means of detection of LAAM and its active, N-demethylated metabolites in small samples of blood, it may enable patient compliance to be more easily assessed by allowing samples to be collected by a simple finger-prick technique.

Pharmacokinetics of methamphetamine self-administered to human subjects by smoking S-(+)-methamphetamine hydrochloride

S-(+)-methamphetamine hydrochloride ("ice") is abused by smoking (inhaling the vapors of the material). Male human volunteers inhaled the drug from a pipe heated at 300 degrees-305 degrees C for an average inhaled dose of 21.8 +/- 0.3 (SE) mg. The same volunteers were given an intravenous injection of 15.5 mg of S-(+)-methamphetamine hydrochloride. Methamphetamine and its metabolite amphetamine were analyzed in plasma, saliva, and urine by gas chromatography. The bioavailability of smoked methamphetamine was 90.3 +/- 10.4%. (Oral bioavailability calculated from this study and a previous one was 67.2 +/- 3.1%). The geometric mean plasma half-life was 11.1 hr for smoked methamphetamine and 12.2 hr for the intravenous drug. These values agreed with urinary excretion rate data. The volume of distribution in the elimination phase was 3.24 +/- 0.36 liter/kg for the smoked dose and 3.73 +/- 0.59 liter/kg for the intravenous dose. The mean residence times were 11.5 +/- 0.5 hr and 11.3 +/- 1.74 hr for the two routes. Metabolic clearance represented 58 and 55%, respectively, of the total clearance. Significant amounts of the drug (37-45% of the nominal dose) were excreted in urine as methamphetamine and lesser amounts (7% of the nominal molar dose) as amphetamine. Renal clearance was equivalent for the two routes. Methamphetamine concentrations in plasma after inhalation showed a plateau. A model involving both a fast and a slow input function fit the data from 4 of the 6 subjects and indicated a terminal elimination rate that agreed with results from model-independent pharmacokinetic calculations. The drug caused significant subjective and cardiovascular effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of oral methamphetamine and effects of repeated daily dosing in humans

The pharmacokinetics of orally administered S-(+)-methamphetamine-d3 were investigated in human male volunteers before and after a 13-day course of a slow release form of S-methamphetamine hydrochloride. A one-compartment pharmacokinetic model incorporating a lag time fits the data best. The average elimination half-life was 10.1 hr (range of 6.4-15.1 hr). There were no statistically significant differences in pharmacokinetic parameters when a low dose (0.125 mg/kg) was given before and after the 13-day oral regimen. When a higher challenge dose (0.250 mg/kg) was used, the maximum plasma concentration of methamphetamine-d3 was slightly but significantly greater when the test dose was given at the end of the oral dosing period than when it was given at the beginning. Although minor differences in pharmacokinetics occur after subchronic treatment with low doses of methamphetamine, their result would be to increase plasma concentration of the drug. Therefore, development of pharmacodynamic tolerance to methamphetamine could not be explained on the grounds of a change in pharmacokinetics.

Evaluation of a 1-year levonorgestrel-releasing contraceptive implant: side effects, release rates, and biodegradability

OBJECTIVE

To determine the release rates, effects on ovulation, and side effects of two lengths of a biodegradable, subdermal contraceptive implant containing levonorgestrel in a caprolactone capsule.

DESIGN

Phase II randomized clinical trial.

SETTING

Public family planning clinic at an urban general hospital.

PARTICIPANTS

Forty-eight healthy, parous, ovulating volunteers.

INTERVENTION

Subjects were randomly assigned either a 2.5- or a 4.0-cm contraceptive capsule that was worn under the skin of the upper arm for 1 year if not removed earlier for other reasons.

MAIN OUTCOME MEASURES

Serum concentrations of levonorgestrel, progesterone, estradiol, and lipoproteins were measured as were metabolic parameters. Vaginal bleeding and other side effects were recorded. After implant removal, remaining levonorgestrel, capsule viscosity, and molecular weight were measured.

RESULTS

The 4-cm implant provided serum concentrations of levonorgestrel ranging from 0.65 ng/mL shortly after insertion to 0.20 ng/mL at 12 months, but the 2.5-cm implant resulted in levels too low for contraception. The 4-cm implant suppressed ovulation in approximately 80% of cycles over 1 year of use, but the 2.5-cm implant failed to suppress ovulation. The implants were rapidly and easily inserted and removed. They retained structural integrity through 1 year of use. Of 48 subjects, 32 had abnormal bleeding patterns; the mean number of days of bleeding per month was 7 with 23 days between episodes. Women using capronor maintained normal metabolic parameters except that low-density lipoprotein decreased slightly.

CONCLUSIONS

The 4.0-cm implant is a promising contraceptive. There were no important metabolic effects, but there were bothersome minor side effects typical of progestin-only contraception.

Influence of age, performance status, body weight, and tumor type in individuals with cancer on the disposition of warfarin and its enantiomers: Department of Veterans Affairs cooperative study number 75

Plasma warfarin and its R,S enantiomer concentrations, one-stage prothrombin times, and mean daily warfarin doses were analyzed in 196 patients given warfarin. These individuals were part of a controlled clinical trial that examined the effect of warfarin as an adjuvant to "standard" treatment in a variety of malignancies. Neither the plasma warfarin concentration nor the daily warfarin dose required to produce a given degree of prothrombin-time prolongation was influenced by age or body weight in these subjects. When the data were analyzed by performance status, we noted several variations of interest. Individuals with different tumor types demonstrated disparities in warfarin disposition. Patients with colorectal cancer, for example, required lower mean daily warfarin doses to achieve a given degree of one-stage prothrombin time prolongation. Analysis of warfarin enantiomers (R,S) in a selected group of patients demonstrated a lower-than-normal ratio (2:1) for the colorectal cancer group (1.42:1) because of an apparent decrease in the plasma R component. In contrast, patients with head and neck cancer demonstrated a ratio of 2.85:1, and the R component was elevated. Warfarin disposition and the effect of warfarin on vitamin K-dependent clotting factor production were altered in the patients with cancer reported in this study. The mechanisms for these alterations are complex and not completely understood.

The pharmacologic effects of daily marijuana smoking in humans

Six healthy male, paid volunteers smoked one NIDA cigarette containing 1.0% THC each day for 13 consecutive days. They were tested before and after the period of drug administration by the following procedure: the subjects smoked one NIDA marijuana cigarette containing 1.0% THC followed 15 minutes later by the intravenous infusion of 52 micrograms/min of deuterated THC for 50 minutes. The THC plasma concentrations, ratings of "high" and heart rate effects produced by the combined drug administration were measured, and absolute bioavailability of smoked THC was calculated on Days 1 and 22. Statistical analyses indicate that the only significant changes induced by daily marijuana exposure were in cardioacceleration.

Analytical methods validation: bioavailability, bioequivalence and pharmacokinetic studies. Conference report

This is a summary report of the conference on Analytical Methods Validation: Bioavailability, Bioequivalence and Pharmacokinetic Studies. The conference was held from December 3 to 5, 1990 in the Washington, DC area and was sponsored by the American Association of Pharmaceutical Scientists, US Food and Drug Administration, Federation International Pharmaceutique, Health Protection Branch (Canada) and Association of Official Analytical Chemists. The purpose of the report is to represent our assessment of the major agreements and issues discussed at the conference. The report is also intended to provide guiding principles for validation of analytical methods employed in bioavailability, bioequivalence and pharmacokinetic studies in man and animals. The objectives of the conference were: 1. To reach a consensus on what should be required in analytical methods validation and the procedures to establish validation; 2. To determine processes of application of the validation procedures in the bioavailability, bioequivalence and pharmacokinetic studies; 3. To develop a report on analytical methods validation (which may be referred to in developing future formal guidelines). Acceptable standards for documenting and validating analytical methods with regard to processes, parameters or data treatments were discussed because of their importance in assessment of pharmacokinetic, bioavailability and bioequivalence studies. Other topics which were considered essential in the conduct of pharmacokinetic studies or in establishing bioequivalency criteria, including measurement of drug metabolites and stereoselective determinations, were also deliberated.

Clinical effects of daily methamphetamine administration

This study investigated alterations in the disposition and pharmacodynamics of methamphetamine HCl after daily administration. Six male paid volunteers familiar with the use of amphetamines participated. Each subject was administered 10 mg of methamphetamine HCl as a slow-release preparation (Desoxyn Gradumets) at 9 a.m. for 13 consecutive days (days 2-14 of the study). On days 1 and 15 the subjects were challenged with 10 mg of oral deuterated methamphetamine HCl. Deuterated drug was used to differentiate plasma concentrations of challenge doses from those of daily doses. The heart rate, subjective perception of "high," and plasma concentrations of methamphetamine were examined on days 1 and 15. Repeated ANOVA measures indicate that a significant decrease in heart-rate acceleration in response to methamphetamine challenge occurred on day 15 [F(1,5) = 8.26, p less than or equal to 0.035]. However, no significant change in either the subjective ratings of "high" or the plasma concentrations of deuterated methamphetamine occurred. These findings indicate that the disposition of methamphetamine and its subjective effects were not altered by this period of daily exposure to a low dose of the drug. In contrast, tolerance to the heart-rate accelerating effect was observed.

Clinical effects of methamphetamine vapor inhalation

Despite the increasing popularity of crystalline methamphetamine ("ice") vapor inhalation, no investigations have reported drug plasma concentrations and effects. Under controlled laboratory conditions, six subjects were studied. Plasma concentrations of methamphetamine were determined, and subjective and cardiovascular effects were measured. Methamphetamine appeared in plasma rapidly, increased slowly over the next four hours and then progressively declined. The dose of methamphetamine administered produced modest ratings of subjective drug effects, and moderate changes in cardiovascular parameters. Both subjective and cardiovascular effects rapidly decreased despite the presence of sustained concentrations of methamphetamine in plasma.

Application of countercurrent chromatography/thermospray mass spectrometry for the identification of bioactive lignans from plant natural products

The versatility and resolving power of countercurrent chromatography (CCC) has been demonstrated with a newly developed analytical high-speed planet centrifuge system. Interfacing countercurrent chromatography with mass spectrometry (MS) provides a new analytical methodology that integrates the advantages of countercurrent chromatography with the low detection limit and identification capability of mass spectrometry. In this paper the capability of thermospray CCC/MS is demonstrated in identifying and validating the bioactive and structurally known lignans from a crude extract of Schisandra rubriflora Rhed et Wils, a traditional Chinese herbal medicine for treatment of hepatitis.