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Biomedical subjects

B Law

Publications and source records attributed to B Law.

At least 73 records · Page 4Linked to original sources
PubMed1987

Analysis of basic compounds on a silica column with an aqueous methanol eluent. The use of quantitative structure-retention relationships in metabolite identification.

High-performance liquid chromatography data for 69 mono-functional aryl-alkyl amines was generated using a silica column and an aqueous methanol eluent (pH 9.1). Retention was shown to be due to a cation-exchange mechanism and was controlled by the solute pKa and the degree and type of substitution at or near the basic centre. The effect of various substituents--some common to metabolic transformation--could be quantified using the group contribution values (tau). The study was extended to include a further 32 compounds representative of five diverse drug classes. The group contribution data for these drugs and metabolites were similar to those for the model compounds. A number of common biotransformations were well characterised, including N-desmethylation, N,N-didesmethylation and ring hydroxylation. The data demonstrates how the group contribution values can be used to help elucidate the identity of a metabolite from chromatographic data.

Alkalies↗
PubMed1987

Comparison of nasopharyngeal aspirate and nasopharyngeal swab specimens for respiratory syncytial virus diagnosis by cell culture, indirect immunofluorescence assay, and enzyme-linked immunosorbent assay.

Paired nasopharyngeal aspirate (NPA) and nasopharyngeal swab (NPS) specimens obtained from each of 32 hospitalized infants with X-ray-confirmed pneumonia (91%) or bronchiolitis were tested for respiratory syncytial virus (RSV) infection by virus culture, the indirect immunofluorescent-antibody (IFA) technique, enzyme-linked immunosorbent assay (ELISA; Ortho Diagnostic Systems, Inc.), and spot hybridization with a human genomic probe to quantitate cellular DNA. RSV was isolated in cell cultures from 72% (23 of 32) of patients by using NPA specimens compared with 47% (15 of 32) by using NPS specimens. With tissue culture positivity as the reference test, the sensitivities of the ELISA on NPA and NPS specimens were found to be 69% (16 of 23) and 61% (14 of 23), respectively, with a specificity and a positive predictive value from both sites of 100%. The sensitivities of the IFA technique compared with the cell culture on NPA and NPS specimens were 61% (14 of 23) and 52% (12 of 23) with specificities of 89 and 78% and positive predictive values of 96 and 92%, respectively. Despite the recovery of significantly more cells (as shown by detection of more cellular DNA by using NPA specimens), virus was detected by the IFA technique or ELISA at similar frequencies in paired specimens. However, virus was recovered more often from NPA than NPS specimens by cell culture, and ELISA optical density readings and the number of RSV-positive fluorescing cells were greater for NPA specimens. NPA specimen collection was less traumatic for the patient, was an easier procedure for the physician to perform, and provided a superior laboratory specimen for RSV diagnosis than the NPS technique.

Animals↗
PubMed1986

High-performance liquid chromatography systems for the separation of benzodiazepines and their metabolites.

The high-performance liquid chromatographic (HPLC) retention characteristics of 21 benzodiazepine drugs and some of their metabolites have been examined on both silica and ODS-silica packing materials. Four HPLC systems have been considered and retention data are presented for the drugs on these systems. The correlation of retention data on the systems is considered with reference to the problem of identifying unknown benzodiazepines.

Anti-Anxiety Agents↗
PubMed1986

Appraisal of narrow-bore (1 mm I.D.) high-performance liquid chromatography columns with view to the requirements of routine drug analysis.

The potential advantages of using 1-mm bore high-performance liquid chromatography columns to replace conventional 4-5-mm bore columns for routine drug analysis have been considered in the light of various claims and counter-claims in the scientific literature. Experimental work has been conducted to measure the changes in mass sensitivity when using both UV and electrochemical detection. Further work has investigated the coupling of these narrow-bore columns in order to achieve high plate counts with particular reference to the influence of peak asymmetry. Finally the linking of the narrow-bore columns to a mass spectrometer with a moving-belt interface has been examined. All results are discussed with reference to the needs of the routine analyst.

Chromatography, High Pressure Liquid↗
PubMed1986

Patterns in sharp force fatalities--a comprehensive forensic medical study.

A ten-year series of 142 homicidal fatalities caused by sharp force injury was studied with the aim to systematize information inherent in the characteristics of the victim and the pattern of injuries. The population of victims consisted of 112 males (79%) and 30 females (21%); among perpetrators, 125 (88%) were males. Among victims as well as among perpetrators, persons of non-Swedish origin were overrepresented in relation to their share of the nonselected population. In 82 cases (58%), one or two wounds had been inflicted; in 23 cases (16%), ten or more wounds. In the latter group, eleven victims but no perpetrators were female. In the majority of cases victim and perpetrator were known to each other, and in instances of multiple wounding, a close relationship between the two was clearly more common than in the group of one- to two-wound fatalities. Tests for blood alcohol were positive in 86 of 116 victims (74%), the majority being in elimination phase. Furthermore, 96 of 120 perpetrators (80%) had positive tests or were known to be drunk at the time of the killing. In multiple wound fatalities, alcohol inebriation was less common both among victims and perpetrators. In these cases, the two persons involved were usually closely related or intimately known to each other, and in the absence of psychiatric disorder in the assailant, the motive was of a passionate type.

Accidents↗
PubMed1984

High-performance liquid chromatography retention data for 84 basic drugs of forensic interest on a silica column using an aqueous methanol eluent.

High-performance liquid chromatography retention characteristics have been measured for 84 basic drugs of forensic interest using a silica column with a methanol-aqueous ammonium nitrate eluent. The drugs are from two classes of major interest, namely, the narcotic analgesics (including antagonists, metabolites and analogues) and drugs structurally and pharmacologically related to amphetamine.

Amphetamine↗
PubMed1984

Forensic aspects of the metabolism and excretion of cannabinoids following oral ingestion of cannabis resin.

Following oral ingestion of cannabis resin, delta 9-THC-11-oic acid and its O-ester glucuronide were detected using RIA and combined hplc/RIA and shown to be major plasma metabolites of delta 9-THC. delta 9-THC-11-oic acid was not excreted in the urine in significant concentrations, the glucuronide conjugate being the major urinary metabolite detected. delta 9-THC metabolites were detected in blood for up to 5 days and in urine for up to 12 days following a single oral dose of delta 9-THC (20 mg). Estimates for the half life of delta 9-THC-11-oic acid and its glucuronide in plasma, and total metabolites in urine have been obtained. Interpretation of blood or urine total cannabinoid levels is most difficult, however, drug/metabolite ratios and metabolite/metabolite ratios may have potential for indicating recent cannabis use.

Adult↗
PubMed1984

Passive inhalation of cannabis smoke.

Six volunteers each smoked simultaneously, in a small unventilated room (volume 27 950 litre), a cannabis cigarette containing 17.1 mg delta 9-tetrahydrocannabinol (THC). A further four subjects - passive inhalers - remained in the room during smoking and afterwards for a total of 3 h. Blood and urine samples were taken from all ten subjects and analysed by radioimmunoassay for THC metabolites. The blood samples from the passive subjects taken up to 3 h after the start of exposure to cannabis smoke showed a complete absence of cannabinoids. In contrast, their urine samples taken up to 6 h after exposure showed significant concentrations of cannabinoid metabolites (less than or equal to 6.8 ng ml-1). These data, taken with the results of other workers, show passive inhalation of cannabis smoke to be possible. These results have important implications for forensic toxicologists who are frequently called upon to interpret cannabinoid levels in body fluids.

Adult↗
PubMed1983

Amphetamine radioimmunoassay: chemical tuning of specificity.

Four [125I]iodine labelled amphetamine derivatives were synthesised. Three of these proved useful in the development of radioimmunoassays for amphetamine. The assays, all using the same antiserum, had widely differing specificities for compounds closely related to amphetamine. Thus, chemical modification of the radiotracer was used to tune radioimmunoassay specificity without recourse to the production of different antisera.

Amphetamines↗