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PubMed1990

Novel strategies for clinical drug analysis with new column technology in liquid chromatography.

Clinical drug analysis has been the focus of much attention and controversy because of the increase in substance abuse testing of addicts, patients, employees and others, in addition to the rapidly growing fields of therapeutic drug monitoring and clinical toxicology. This review focuses on the latest methodological and technological advances in liquid chromatography (LC) as it is applied to clinical drug analysis. Based on the author's experience, key chromatographic parameters such as carbon load, functionalities and temperature are proposed for the separation of structurally similar metabolites and for resolving chromatographic interferences by other drugs and metabolites. Novel sample preparation for cyclosporine and gradient elution of its metabolites are reviewed, followed by an update on monitoring of 3'-azido-3'-deoxythymidine with emphasis on automated sample preparation. Various approaches of direct sample analysis are advocated for increased efficiency as a result of minimal sample preparation and potential advantages such as decreased exposure of personnel to infectious samples. An update of microbore LC indicates that 2-mm columns may be readily used for clinical paediatric and neonatal analysis without dedicated chromatographs. Potential applications of multidimensional-multimodal chromatography include analyses of a cocaine impurity, anticonvulsants, antidepressants, and five ingredients of a common cold medication.

Body Fluids↗
PubMed2005

Dissociation related to subjective memory fragmentation and intrusions but not to objective memory disturbances.

The present study was a replication of Kindt and Van den Hout (Behaviour Research and Therapy 41 (2003) 167) with several methodological adaptations. Two experiments were designed to test whether state dissociation is related to objective memory disturbances, or whether dissociation is confined to the realm of subjective experience. High trait dissociative participants (N(exp.1)=25; N(exp.2)=25) and low trait dissociative participants (N(exp.1)=25; N(exp.2)=25) were selected from normal samples (N(exp.1)=372; N(exp.2)=341) on basis of scores on the Dissociative Experience Scale (DES). Participants watched an extremely aversive film, after which state dissociation was measured by the Peri-traumatic Dissociative Experience Questionnaire (PDEQ). Memory disturbances were assessed 4h later (Exp. 1) or 1 week later (Exp. 2). Objective memory disturbances were assessed by a sequential memory task, items tapping perceptual representations (Exp. 1), or an open question with respect to the remembrance of the film (Exp. 2). Subjective memory disturbances were measured by means of visual analogue scales assessing fragmentation and intrusions. The two experiments provided a fairly exact replication of an earlier experiment (Behaviour Research and Therapy 41 (2003) 167-178), indicating a relation between dissociation and memory disturbances that appeared to be confined to the subjective experience of memory.

Adult↗
PubMed2002

Introduction to the principles of ultramicroheptodes in ring-disk interactions.

The use of ring-disk ultramicroelectrodes as tips as a means of extending the methodology of the scanning electrochemical microscope is described. Electrodes consisting of one centered disk with six interconnected disks surrounding it served as the ring-disk electrodes. Basic experiments illustrate the behavior in the feedback mode and the generation collection mode. The dependence on the electrodes' size, both potentials, the tip-sample distance, and the local properties of the underying sample were studied. When approaching an electrode to the surface of a sample, steady-state collection efficiencies between zero and unity were elegantly altered by adjusting the distance between tip and sample. The shielding factor could be varied between 0.25 and 0.82 the same way. Concerning feedback methods, the results presented illustrate the new principle of applying a precisely located external stimulus as a separate electrochemical means of analyzing the sample's response. Obviously, this technique can be extended to irreversible redox mediators, which are not treated here explicitly, but give this concept even greater flexibility. The interpretation of such data can be deduced directly from this contribution.

Journal Article↗
PubMed2003

Efficient chiral discrimination by 77Se NMR.

[reaction: see text] Several (77)Se NMR experiments were performed by titrating a sample of selenides with the chiral shift reagent methylbenzylamine (MBA), followed by acquisition of (77)Se NMR spectra. Eventually, we observed the appearance of two anisochronous resonances, with a relatively large separation, from 37 to 56 Hz, corresponding to the formation of the diastereomeric complexes. This methodology avoids derivatization processes, and the studied compound can be easily recovered from the NMR tube.

Journal Article↗
PubMed1992

Salivary excretion of drugs in children: theoretical and practical issues in therapeutic drug monitoring.

Studies suggest that saliva could be used instead of blood in the therapeutic monitoring of many drugs. This has distinct advantages in pediatrics and neonatology as saliva sampling is painless and spares blood. Stimulation of saliva secretion with a chemical stimulus (i.e. citric acid applied over the tongue) facilitates the study of younger patients. Secretory and reabsorptive processes which take place in the ductal system of the salivary glands, and the rate of flow of the secretion play major roles in the determination of the concentration of solutes in saliva. Drug passage into saliva follows the general principles of movement of drugs across biologic membranes. Only the unbound fraction of the drug in plasma is available for diffusion into saliva and a relationship exists between saliva pH and the saliva/plasma concentration ratio of many polar drugs (tolbutamide, propranolol, procainamide, etc.). However, deviations from the pH theory exist and the inter -and intra-individual variations in saliva/plasma concentration ratios of salicylate and procainamide cannot be explained solely on the basis of fluctuations of salivary pH; on the other hand, a useful relationship exists between plasma and saliva phenobarbital concentrations with no need to correct for saliva pH. The use of stimulated saliva has several advantages over resting saliva: a larger volume of the sample is obtained, the pH gradient between plasma and saliva is smaller, the variability in saliva/plasma concentration ratios of some drugs is narrowed, and less specimens are too viscous or discolored to allow drug analysis. Thorough rinsing of the mouth is required prior to saliva sampling as remnants of orally administered medicines may contaminate saliva specimens and give spuriously high values. Deviation from a simple but strict methodology accounts for some of the discrepancies found in the literature. Studies in children uniformly recommend saliva for therapeutic monitoring of phenytoin, carbamazepine and phenobarbital. Saliva sampling for therapeutic monitoring of ethosuximide, primidone and digoxin in infants and children, and of theophylline and caffeine in the neonate is promising, but little pediatric experience is available as yet. The value of saliva in therapeutic monitoring of theophylline in children is still controversial. Little of highly polar compounds such as aminoglycosides, and of polar highly protein bound drugs such as valproic acid is present in saliva. More data are still needed on the excretion of drugs in saliva in infants and in acutely ill children, and few data exist in the premature and full-term neonate.

Child↗
PubMed2003

Factors contributing to occupational stress experienced by individuals employed in the fast food industry.

The present study, examined through survey research methodology, the factors or combination of factors which appear to contribute to the experience of occupational stress of individuals working in the fast-food industry. The Occupational Stress Indicator was used. Preliminary findings showed that there exists, several compound factors, which appear to be the most frequently encountered factors by the sample tested, such as the way they feel about their job; the way they behave generally; the way they interpret events around them; the sources of pressure in their job; and the way they cope with stress they experience. It appears that there are statistically significant differences between males and females as regards to the way they respond to stress, the sources of pressure in their job and the way they cope with stress they experience. Also, statistically significant differences exist between individuals in managerial and non-managerial positions, as regards to their personality type, the degree of ambition, and work dedication they possess.

Adult↗
PubMedDate not supplied

A review of laboratory methods for the analysis of opiates and diluents in illicit drug traffic.

The paper summarizes the utility of currently available analytical techniques for the detection of heroin and other opiates in nonbiological samples. It focuses on the following techniques: thin-layer chromatography/high-performance thin-layer chromatography, gas-liquid chromatography, high-performance liquid chromatography, gas chromatography/mass spectrometry. Recent innovations for the identification of compounds using high-performance liquid chromatographic techniques are also discussed. The applications of each methodology based on the experience of the authors are outlined.

Chromatography↗
PubMed1994

The doctor-patient relationship and malpractice. Lessons from plaintiff depositions.

BACKGROUND: The current literature does not provide an answer to the question, "What prompts patients to sue doctors or hospitals?" Not all adverse outcomes result in suits, and threatened suits do not always involve adverse outcomes. The exploration of other factors has been hampered by the lack of a methodology to contact plaintiffs and elicit their views about their experience in delivered health care. This study employed the transcripts of discovery depositions of plaintiffs as a source of insight into the issues that prompted individuals to file a malpractice claim. METHODS: This study is a descriptive series review of a convenience sample of 45 plaintiffs' depositions selected randomly from 67 depositions made available from settled malpractice suits filed between 1985 and 1987 against a large metropolitan medical center. Information extracted from each deposition included the alleged injury; the presence of the question, "Why are you suing?" and, if present, the answer; the presence of problematic relationship issues between providers and patients and/or families and, if present, the discourse supporting it; the presence of the question, "Did a health professional suggest maloccurrence?" and, if yes, who. Using a process of consensual validation, relationship issues were organized into groups of more generalized categories suggested by the data. Answers to the questions, "Why are you suing?" and "Who suggested maloccurrence?" are described. RESULTS: Problematic relationship issues were identified in 71% of the depositions with an interrater reliability of 93.3%. Four themes emerged from the descriptive review of the 3787 pages of transcript: deserting the patient (32%), devaluing patient and/or family views (29%), delivering information poorly (26%), and failing to understand the patient and/or family perspective (13%). Thirty-one plaintiffs were asked if health professionals suggested maloccurrence. Fifty-four percent (n = 17) responded affirmatively. The postoutcome-consulting specialist was named in 71% (n = 12) of the depositions in which maloccurrence was allegedly suggested. CONCLUSIONS: In our sample, the decision to litigate was often associated with a perceived lack of caring and/or collaboration in the delivery of health care. The issues identified included perceived unavailability, discounting patient and/or family concerns, poor delivery of information, and lack of understanding the patient and/or family perspective. Particular attention should be paid to the postadverse-event consultant-patient interaction.

Adult↗
PubMed1983

The incidence and prevalence of intrafamilial and extrafamilial sexual abuse of female children.

Data obtained from a random sample of 930 adult women in San Francisco provide the soundest basis heretofore available for estimating the prevalence of intrafamilial and extrafamilial sexual abuse of female children. This article describes the methodology of this survey, as well as some of the key findings. For example: 16% of these women reported at least one experience of intrafamilial sexual abuse before the age of 18 years; 12% reported at least one such experience before the age of 14 years; 31% reported at least one experience of extrafamilial sexual abuse before the age of 18 years; and 20% reported at least one such experience before the age of 14 years. When both categories of sexual abuse are combined, 38% reported at least one experience before the age of 18 years; and 28% reported at least one such experience before the age of 14 years. Only 2% of the cases of intrafamilial and 6% of the cases of extrafamilial child sexual abuse were ever reported to the police. A plea is made for the urgent need to recognize the magnitude of the problem of child sexual abuse, and to act to prevent it.

Adolescent↗
PubMed1998

On memories of childhood abuse: a phenomenological study.

OBJECTIVE: To explore the phenomenon of memories and reported recovered memories of childhood abuse, and to examine ways in which clients and therapists assess the veridicality of such memories. METHOD: Qualitative methodology utilizing phenomenological inquiry. Within the context of a wider study exploring perceptions of helpful and unhelpful factors in the therapeutic process, a sub-sample of 36 in-depth interviews with clients, therapists, and therapists who considered themselves to have been abused as children included a focus on abuse-memory experiences. Data were analyzed according to Grounded Theory principles. RESULTS: Participants described six types of abuse-memory experiences. The most frequently reported type was where abuse was known about but kept "out of mind." The six types can be collapsed into three main categories: (1) continual knowledge of abuse (69.5%); (2) unexpected abuse-memories recovered from a prior state of partial knowledge of abuse (16.5%); and (3) abuse-memories recovered from a prior state of no knowledge of abuse (30%). Independent corroboration of recovered memories was rare; and criteria which were reportedly used to assess the veridicality of such memories were problematic when viewed in the light of cognitive psychology research on memory processes. CONCLUSION: It seems that most people who were abused as children have always had continual knowledge of this, although it is often only much later than many connect problems in adult life with the consequences of such abuse. People also experience the recovery of memories of abuse about which they were previously unaware. There is a danger that the specific controversy surrounding "false memories" may become over-generalized contributing to increased public scepticism about the prevalence and negative impact of child abuse, and the potential effectiveness of appropriate therapeutic services.

Adult↗
PubMed2005

Maximal use of minimal libraries through the adaptive substituent reordering algorithm.

This paper describes an adaptive algorithm for interpolation over a library of molecules subjected to synthesis and property assaying. Starting with a coarse sampling of the library compounds, the algorithm finds the optimal substituent orderings on all of the functionalized scaffold sites to allow for accurate property interpolation over all remaining compounds in the full library space. A previous paper introduced the concept of substituent reordering and a smoothness-based criterion to search for optimal orderings (Shenvi, N.; Geremia, J. M.; Rabitz, H. J. Phys. Chem. A 2003, 107, 2066). Here, we propose a data-driven root-mean-squared (RMS) criteria and a combined RMS/smoothness criteria as alternative methods for the discovery of optimal substituent orderings. Error propagation from the property measurements of the sampled compounds is determined to provide confidence intervals on the interpolated molecular property values, and a substituent rescaling technique is introduced to manage poorly designed/sampled libraries. Finally, various factors are explored that can influence the applicability and interpolation quality of the algorithm. An adaptive methodology is proposed to iteratively and efficiently use laboratory experiments to optimize these algorithmic factors, so that the accuracy of property predictions is maximized. The enhanced algorithm is tested on copolymer and transition metal complex libraries, and the results demonstrate the capability of the algorithm to accurately interpolate various properties of both molecular libraries.

Algorithms↗
PubMed2000

Management and treatment perceptions among young adults with asthma in Melbourne: the Australian experience from the European Community Respiratory Health Survey.

OBJECTIVES: As part of the European Community Respiratory Health Survey (ECRHS) in 1992-1993 we assessed management practices and treatment perceptions among young asthmatic adults in Melbourne, Australia. METHODOLOGY: We conducted a postal questionnaire survey of 4500 randomly selected adults (aged 20-44 years), drawn from three electoral districts, of whom 3200 (71%) subjects responded. A randomly selected sample of 1642 respondents, 'enriched' by a further 433 symptomatic subjects, was invited to complete a second phase respiratory questionnaire. RESULTS: The questionnaire was completed by 757 subjects who underwent laboratory testing. A further 119 subjects who were unable to attend the laboratory completed an identical questionnaire by telephone interview (42% response rate). In the second phase, 16% of subjects reported 'current asthma' (group I) as defined by physician confirmation and a recent attack (within 1 year), 10% had confirmed asthma but reported no recent attack (group II) and 74% did not have asthma (group III). Inhaled corticosteroid use was significantly higher in group I than in group II subjects (45% vs 24%, P<0.01), but only 11% of asthmatic subjects overall reported daily prophylactic use. Regular treatment in any form was considered to be 'bad' by 65% of asthmatic subjects and only 43% took medication as prescribed all of the time. CONCLUSION: Despite national education campaigns, the majority of young asthmatic adults in Melbourne did not adhere to prescribed treatment, but continued to rely upon beta2-agonists alone with neglect of regular inhaled corticosteroid which has probably contributed to Australia's continued high asthma morbidity and mortality rates.

Adrenal Cortex Hormones↗
PubMed2006

Root canal treatment in Denmark is most often carried out in carious vital molar teeth and retreatments are rare.

AIM: To study the reasons given by a representative sample of Danish general dental practitioners (GDPs) for undertaking root canal treatment and, to investigate their confidence in performing root canal treatment on molar teeth. METHODOLOGY: A questionnaire was sent to 600 Danish GDPs randomly selected from the roster of the Danish Dental Association. They were asked to recall various factors about their experience of the last root filling they completed, including the reason for treatment and the pulp diagnosis. Self-assessments on 100-mm visual analogue scales (VAS) were reported concerning the confidence in performing root canal treatment of a molar. End-point definitions were 'very easy' (0) and 'very difficult' (100), respectively. Time reports of molar treatments were given in categorized groups. RESULTS: The most frequent reason for performing root canal treatment was caries within the tooth involved (55%). The majority of treatments involved teeth with vital pulps (54%). Retreatments were carried out in 2% of the cases. The confidence in performing root canal treatment varied but was relatively high, expressed as VAS-values below 50. The creation of an aseptic working field was regarded as the most difficult procedure followed by root canal preparation. Fifty-six percent of the responders stated a time frame of 46-75 min to complete root filling in a molar tooth. CONCLUSIONS: Root canal treatment in Denmark was reported to be undertaken most often because of caries. Treatment was typically performed in molar teeth with vital pulp. Even though apical periodontitis was frequently noted in root filled teeth, retreatments were rare. From a subjective perspective root canal treatment was not considered to be very difficult and was carried out relatively rapidly.

Analysis of Variance↗
PubMed1976

Testosterone in human urine as determined by gas-liquid chromatography.

A simple and accurate gas chromatographic method for the determination of testosterone in human urine is described. Radioactive testosterone was added to samples to correct methodological loss. A mild acid hydrolysis under protection of benzene layer gave a single estimate of testosterone glucuronate and sulphate. Paper chromatography and rechromatography on chromatoplate served for preliminary qurification. Testosterone was gas chromatographed as acetate and guantitated by the internal standard procedure and flame ionization detector. Results of control experiments, normal values for female and male subjects and estimations in patients with alterations of androgen hormone metabolism are presented.

Adolescent↗
PubMed1996

What can artificial neural networks teach us about neurodegenerative disorders with extrapyramidal features?

Artificial neural networks (ANNs), computer paradigms that can learn, excel in pattern recognition tasks such as disease diagnosis. Artificial neural networks operate in two different learning modes: supervised, in which a known diagnostic outcome is presented to the ANN, and unsupervised, in which the diagnostic outcome is not presented. A supervised learning ANN could emulate human expert diagnostic performance and identify relevant predictive markers in the diagnostic task, while an unsupervised learning ANN could suggest reasonable alternative diagnostic classification criteria. In the present study, we used ANN methodology to try to overcome the neuropathological difficulties in differentiating the subtypes of progressive supranuclear palsy (PSP), and in differentiating PSP from postencephalitic parkinsonism (PEP) and corticobasal degeneration, or Pick's disease from corticobasal degeneration. First, we applied supervised learning ANN to classify 62 cases of these disorders and to identify diagnostic markers that distinguish them. In a second experiment, we used unsupervised learning ANN to investigate possible alternative nosological classifications. Artificial neural networks input data for each case consisted of values representing histological features, including neurofibrillary tangles, neuronal loss and gliosis found in multiple brain sampling areas. The supervised learning ANN achieved excellent accuracy in classifying PSP but had difficulty classifying the other disorders. This method identified a few features that might help to differentiate PEP, supported currently proposed criteria for Pick's disease, corticobasal degeneration and typical PSP, but detected no features to characterize the atypical subtype of PSP. In general, unsupervised learning ANN supported the present nosological classification for PSP, PEP, Pick's disease and corticobasal degeneration, although it overlapped some groups. Artificial neural networks methodology appears promising for studying neurodegenerative disorders.

Basal Ganglia Diseases↗
PubMed1999

The use of capillary high performance liquid chromatography with electrospray mass spectrometry for the analysis of small volume blood samples from serially bled mice to determine the pharmacokinetics of early discovery compounds.

The methodology described demonstrates, for the first time, the feasibility of performing pharmacokinetic studies in the serially bled mouse model to support the early development of discovery compounds. Sample analysis, using capillary high performance liquid chromatography combined with tandem mass spectrometry, has facilitated the achievement of this milestone and has successfully been applied to determine pharmacokinetic information following both intravenous and oral administration of a single discovery compound. The methodologies described demonstrate potential for a reduction in the amount of new chemical entity required to undertake pharmacokinetic studies. Typically, such studies are performed in larger rodents with a significantly increased body mass (ten times in the case of the rat) and therefore it follows that to undertake the same experiment in the mouse would require ten times less compound to effect an equivalent dose. Conventionally, pharmacokinetic studies to obtain both intravenous and oral information, e.g. clearance and half-life, and the resultant bioavailability have been performed using two parallel groups of rodents, collecting blood by exsanguination, separating off the plasma and analysing this using conventional liquid chromatography/tandem mass spectrometry. The use of capillary high performance liquid chromatography (HPLC) has facilitated the analysis of small volume blood samples by increasing the effective sensitivity of the analytical method. Consequently, we have established a protocol for serially bleeding mice thus reducing the number of animals and so further reducing the amount of compound required for such experiments. This paper reports data obtained from collected and processed blood volumes of <20 microL with the subsequent injection of only 1 microL of precipitated extract onto a capillary column.

Administration, Oral↗
PubMed2002

Silver concentrations in Colorado, USA, watersheds using improved methodology.

River water samples were collected at five sites in the state of Colorado, USA, to assess the impact of municipal and industrial discharges on Ag concentrations and speciation in surface waters. Samples were collected and analyzed for total (unfiltered collections), filtered (0.1 and 0.4 microm), particulate (> or = 0.45 microm), and colloidal Ag (3 kDa-0.1 m) using ultraclean protocols. A series of laboratory experiments were conducted to assess bias from sample storage, digestion, and preconcentration protocols. In general, upstream unfiltered and particulate Ag concentrations fell within a fairly narrow range, 3.1 to 21 ng/L and 0.2 to 1.7 microg/g, respectively. Downstream unfiltered and particulate Ag concentrations showed a more broad range, 2.8 to 1,110 ng/L and 0.5 to 104 microg/g, respectively, and reflected attenuated impacts of Ag-laden discharge effluents. However, Ag concentrations in the 0.1-microm filter-passing fraction 0.8 to 1.2 km downstream from major treatment plant effluents were all below the chronic silver criteria. On average, more than 60% of the 0.1-microm filter-passing Ag was associated with colloidal macromolecular organic matter. Silver concentrations in colloids (microg/g) were, on average, the same as those in suspended particulate matter. The percentage abundance of colloidal Ag was similar to that of dissolved organic carbon, suggesting that strong Ag binding ligands exist in both the colloidal and the particle size fractions, as these macromolecular ligands likely play a major role in Ag speciation.

Chemical Industry↗