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R W Allen

Publications and source records attributed to R W Allen.

At least 19 recordsLinked to original sources
PubMed1992

Genetic differences at four DNA typing loci in Finnish, Italian, and mixed Caucasian populations.

Highly polymorphic segments of the human genome containing variable numbers of tandem repeats (VNTRs) have been widely used to establish DNA profiles of individuals for use in forensics. Methods of estimating the probability of occurrence of matching DNA profiles between two randomly selected individuals have been subject to extensive debate regarding the possibility of significant substructure occurring within the major races. We have sampled two Caucasian subpopulations, Finns and Italians, at four commonly used VNTR loci to determine the extent to which the subgroups differ from each other and from a mixed Caucasian database. The data were also analyzed for the occurrence of linkage disequilibrium among the loci. The allele frequency distributions of some loci were found to differ significantly among the subpopulations in a manner consistent with population substructure. Major differences were also found in the probability of occurrence of matching DNA profiles between two individuals chosen at random from the same subpopulation. With respect to the Finnish and Italian subpopulations, the conventional product rule for estimating the probability of a multilocus VNTR match using a mixed Caucasian database consistently yields estimates that are artificially small. Systematic errors of this type were not found using the interim ceiling principle recently advocated in the National Research Council's report [National Research Council (1992) DNA Technology in Forensic Science (Natl. Acad. Sci., Washington)]. The interim ceiling principle is based on currently available racial or ethnic databases and sets an arbitrary lower limit on each VNTR allele frequency. In the future the ceiling frequencies are expected to be established from more adequate data acquired for relevant VNTR loci from multiple subpopulations.

Alleles↗
PubMed1992

Gastric emptying during lumbar extradural analgesia in labour: effect of fentanyl supplementation.

We measured gastric emptying (by paracetamol absorption) and duration of analgesia in 30 women in labour after extradural injection of 0.375% bupivacaine 10 ml either alone or combined with fentanyl 100 micrograms. Treatment was administered double blind by random allocation after the first request for analgesia. The median (range) times to maximal serum concentration of paracetamol were 60 (15-90) min and 75 (30-180) min after administration in the control and fentanyl groups, respectively (P = 0.026), and corresponding mean (95% confidence interval) maximal concentrations of paracetamol were 27.3 (18.8-35.8) micrograms ml-1 and 18.0 (15.1-20.9) micrograms ml-1 (P = 0.020). Mean duration of analgesia, from the first extradural bolus until return of pain in those given bupivacaine alone was 113 (87-139) min and 154 (131-176) min when fentanyl was added to the local anaesthetic (P = 0.016). These results confirm the prolongation of analgesia after fentanyl supplementation of lumbar extradural analgesia, but indicate that it results in delayed gastric emptying.

Acetaminophen↗
PubMed1992

Partial attenuation of the pressor response to endotracheal intubation. A comparison of the effects of intravenous clonidine and fentanyl.

In a randomized, double-blind placebo controlled study, intravenous clonidine, fentanyl and saline were compared for both their effect on the cardiovascular response to intubation, and early post-operative pain. The patients treated with fentanyl and clonidine were more sedated and the requirements for induction agents were lower compared to the control group. On intubation, both the active treatments resulted in a smaller increase in both heart rate and mean arterial pressure compared to the control group. There was no significant difference in recovery times in the three groups. Although the time to first request for analgesia was longer in the clonidine group compared to both the fentanyl and saline groups, the difference in morphine requirements between the groups was not significant. The differences between the two active treatments were not significant, and clonidine offered no additional benefits over fentanyl for this purpose.

Adult↗
PubMed1991

Attenuation of the pressor response to tracheal intubation in hypertensive proteinuric pregnant patients by lignocaine, alfentanil and magnesium sulphate.

The pressor response to intubation is known to be exaggerated in patients with gestational proteinuric hypertension (GPH). The effect of pretreatment with lignocaine 1.5 mg kg-1, magnesium sulphate 40 mg kg-1 or alfentanil 10 micrograms kg-1 on this pressor response was studied in 69 patients with moderate to severe GPH. Systolic arterial pressure exceeded baseline values for the first 5 min after tracheal intubation in the lignocaine group, with a peak increase of 31.6 (SEM 3.6) mm Hg at 2 min after intubation, but no mean increase in pressure occurred in the two other groups. Following intubation, six of 24 mothers in the alfentanil group, six of 21 in the lignocaine group and one of 24 in the magnesium group (P less than 0.05) exhibited a systolic arterial pressure (SAP) greater than 180 mm Hg sustained for 2 min or more. Alfentanil caused the least change in heart rate, but resulted in significant fetal depression.

Alfentanil↗
PubMed1979

Draft protocol for testing calibration and quality control material used with automatic blood-counting apparatus.

A large number of commercial preparations are now available for calibrating or checking the stability of automatic blood counters. Most of these preparations are supplied with 'stated' values though the methods for assigning these values are not described in sufficient detail to allow for an adequate assessment of the validity. The Haemocytometry Panel of the British Committee for Standards in Haematology are therefore proposing a draft protocol for testing calibration and quality control materials. Comments on the draft protocol are invited, either as letters to the Editor of Clinical and Laboratory Haematology or in confidence to the Chairman of the Haemocytometry Panel.

Automation↗
PubMed1977

The mandibular dental arch: Part I, lower incisor position.

The position of the lower incisor with respect to hard tissue references has been evaluated. Two samples were used for this purpose: one containing 78 patients with posttreatment records having a postretention period of at least 4 years, and the other composed of 82 normal occlusions. The results indicated: 1) There was no significant difference in relapse of lower incisor crowding between cases where the lower incisor had been moved lingually, labially, or held in the same relative position during treatment. 2) The position of the maxilla should be considered when placing the lower incisor. The APo plane adequately serves as a guide to this purpose, whereas other reference lines such as mandibular plane or facial plane do not. 3) The positions of the incisors with respect to popular cephalometric reference lines such as APo, NB, or mandibular plane were not correlated with the relapse of mandibular crowding. Therefore, other clinical guides might be more successful for determining stability.

Dental Arch↗
PubMed1977

Informed consent: a medical decision (II).

The obtaining of informed consent prior to urography is a practice of some radiologists based largely on legal considerations. Because of the possibility of inducing anxiety, a relevant factor in idiosyncratic reactions, radiologists should not obtain informed consent prior to the urographic examination.

Contrast Media↗