Search PubMed⌕ Search

Biomedical subjects

A Richards

Publications and source records attributed to A Richards.

At least 19 recordsLinked to original sources
PubMed1997

Fluoride content and mineralization of red deer (Cervus elaphus) antlers and pedicles from fluoride polluted and uncontaminated regions.

Fluoride, calcium, and phosphorus content as well as ashpercentage and ash density of primary antlers and pedicle bones were studiedin nine yearling red deer stags from a fluoride polluted region in NorthBohemia (Czech Republic) and in nine control animals from two uncontaminatedareas in West Germany. Fluoride levels in antlers (845 +/- 257 mgF-/kg ash, mean +/- SD) and pedicles (1,448 +/- 461 mgF-/kg ash) of the N-Bohemian specimens exceeded that of thecontrols (antlers: 206 +/- 124 mg F-/kg ash, pedicles:322 +/- 157 mg F-/kg ash) by factors of 4.1 and 4.5,respectively. Antler and pedicle fluoride concentrations of the deer(n = 18) were closely correlated (r = 0.975,p < 0.001). Analyses of ash percentage and ash density revealed that theantlers of the N-Bohemian deer contained significantly less mineral and weresignificantly less dense than both their pedicles and the control antlers. Inthe pooled antler samples (n = 18), bone fluoride concentration wasnegatively correlated with ash density (r = -0.826, p < 0.001)and ash percentage (r = -0.759, p < 0.001), whereas nonsignificant, positive correlations existed for the pooled pedicle samples. Ash percentage and ash density of the antlers and their correspondingpedicles were uncorrelated. It is concluded that increased fluoride exposureof deer leads to reduced mineral content and mineral density of antler boneand that it is the rapidity of their growth and mineralization that makesantlers especially susceptible to fluoride action. Due to their ability toaccumulate high amounts of fluoride during a defined, limited timespan andthe apparently dose-dependent negative effect of fluoride on their densityand mineral content, (primary) antlers can be recommended as monitoring toolsfor studying environmental pollution by fluorides.

Animals↗
PubMed1997

Running an objective structured clinical examination on a shoestring budget.

BACKGROUND: A major obstacle in the wide implementation of objective clinical structured examinations (OSCEs) is their high cost, averaging $200 to $300 (Canadian dollars, CDN) per candidate and estimated at up to CDN$900 per candidate if all "hidden" administrative costs are included. METHODS: A detailed cost analysis of preparing and administering OSCEs at 1 institution was undertaken over 2 years. An 18-station, 6-minute-per-station OSCE was given to a 72-student third-year medical class. RESULTS: The total cost of the OSCE was CDN$5,010, or $70 per student. The key factors in reaching this significantly lower per-student OSCE cost included: judicious use of standardized patients, use of academic faculty for preparing and marking the stations, and decreased secretarial and other administrative costs. CONCLUSIONS: Data suggest that OSCEs can be set up with reasonable cost and limited resources even in smaller institutions. Cost should not be considered a major obstacle in implementing this excellent examination type in undergraduate medical education.

Canada↗
PubMed1997

Anxiety and memory: a recall bias for threatening words in high anxiety.

Few studies have directly examined the relationship between trait anxiety and explicit memory for emotionally congruent material. Evidence from clinically anxious subjects, however, suggests a recall bias favouring non-threatening words as opposed to threatening words. Two experiments are reported which examined the recall performance of high- and low-trait anxious subjects. Contrary to the clinical anxiety findings, there was evidence of a recall bias for threatening rather than non-threatening words in the high-trait anxious group. Further analysis, however, revealed that the recall bias was associated with state anxiety and depression levels rather than trait anxiety. The two experiments also showed that recall was greater for words appearing at the end of the list as opposed to words presented elsewhere in the list. The theoretical and methodological implications of these findings are discussed.

Adult↗
PubMed1997

A comparison of the effects of two anabolic agents (fluoride and PTH) on ash density and bone strength assessed in an osteopenic rat model.

The aim of this investigation was to compare the effects of sodium fluoride (NaF) and parathyroid hormone (PTH) on ash density and strength in an osteopenic rat model. The study comprised 66 female virgin rats divided into the following 11 groups, each comprising six animals: baseline controls; baseline ovariectomized (ovx); intact controls (5 and 16 weeks), ovx controls (5 and 16 weeks); ovx-treated with PTH (0.02 mg/kg per day, 5 and 16 weeks); ovx treated with NaF (10 mg/kg per day, 5 and 16 weeks); ovx-treated with NaF (1.0 mg/kg per day, 16 weeks). Ovariectomy was performed at 12 weeks of age, 14 weeks prior to start of treatment. Ash density, bone fluoride content, and biomechanical analyses were performed on femoral cortical bone, the right femoral neck, and the sixth lumbar vertebral body. ovx had no effect on cortical bone, whereas the femoral neck displayed a significantly lower bone strength in ovx baseline animals compared with intact baseline rats (p < 0.05). Vertebral ash density was found to be significantly decreased in ovx rats after 5 and 16 weeks (p < 0.05). Treatment with fluoride had little effect on the osteopenic rat skeleton. Cortical ash density was significantly lower than ovx and intact groups in the high-dose-treated rats after 5 (p < 0.01) but not after 16 weeks. High doses of fluoride for 16 weeks induced a significant increase in maximum load and normalized strength in cortical bone when compared with intact animals (p < 0.05), but not at the other bone sites. Cortical bone strength was not different from the ovx animals at either timepoint. In fluoride-treated animals, femoral neck bone strength, vertebral body bone strength, bone quality, and ash density were found to be at about ovx levels and, in the vertebral body, significantly lower than intact animals (p < 0.05, p < 0.01). In contrast, treatment with PTH increased ash density, bone strength, and bone quality to above ovx levels (p < 0.01), and above the level of the intact animals also, although significant values were reached for cortical bone strength only (p < 0.01). Additionally, biomechanical competence and ash density measurements were significantly higher in PTH-treated rats compared with fluoride-treated rats. In conclusion, this study has shown that PTH has a highly anabolic effect and is capable of effectively restoring ovx-induced loss of bone mass and biomechanical competence. In addition, in this osteopenic rat model, PTH proved much more advantageous than treatment with fluoride, which failed to restore the ovx-induced loss of bone strength.

Animals↗
PubMed1997

Cognitive processing and trait anxiety in typically developing children: evidence for an interpretation bias.

In this study the authors examined whether increases in children's levels of self-reported trait anxiety would be related to their interpretation of ambiguous stimuli. By using the Revised Children's Manifest Anxiety Scale (C. R. Reynolds & B. O. Richmond, 1985), the authors obtained measurements of anxiety for 40 children ages 7 and 9 years. Interpretation of ambiguous stimuli was measured by using a pictorial homophone task, where homophones could be interpreted as either threatening or neutral. Results showed that children's interpretations of homophones was significantly predicted by level of anxiety. Increases in levels of trait anxiety were positively associated with threatening interpretations of homophones.

Anxiety↗
PubMed1997

Surgery on the Internet. Part 1: The origins of the Internet.

The last few years have seen a dramatic increase in the size and use of the Internet; indeed recent figures estimate that the number of people with Internet access is increasing by up to 20 per cent monthly with over 30 million people now connected world wide. Many organisations, including The Royal College of Surgeons of England, now offer their own world wide web (WWW) sites. There are a number of areas and facilities on the Internet which are of particular interest to the surgeon; these include access to journals and textbooks, information of surgical units world-wide, e-mail and newsgroups discussing various surgical topics. The aim of this article, together with the two others in the series is to explain the steps necessary to get connected to the Internet and to illustrate some of the main areas of interest to the surgeon. This, the first of the articles will describe the origins of the Internet and the equipment and process required to get connected.

Computer Communication Networks↗
PubMed1996

The complete cDNA sequence of laminin alpha 4 and its relationship to the other human laminin alpha chains.

We previously localised the gene (LAMA4) encoding a novel laminin alpha 4 chain to chromosome 6q21. In this study, we describe the complete coding sequence and compare the protein with the other three known human laminin alpha chains. Although closely linked to LAMA2, the LAMA4 product most closely resembles laminin alpha 3, a constituent of laminin 5. Like laminin alpha 3A, the alpha 4 chain is a truncated version of the alpha 1 and alpha 2 chains, with a much reduced short arm. While the alpha 4 molecule is most similar to alpha 3, it shares some features of the C-terminal domains G4 and G5 in common with alpha 2. Unlike the LAMA3 gene, LAMA4 appears to encode only a single transcript, as determined by 5' rapid amplification of cDNA ends. The cDNA sequence encodes 1816 amino acids, which include a 24-residue signal peptide. The gene is expressed in skin, placenta, heart, lung, skeletal muscle, and pancreas. We have also shown that the mRNA can be readily reverse transcribed and amplified from cultured dermal fibroblasts.

Alternative Splicing↗
PubMed1996

Development of a dual target-PCR for detection and characterization of measles virus in clinical specimens.

A polymerase chain reaction (PCR) method was developed for detecting measles virus (MV) RNA in a variety of clinical samples using primer pairs in the nucleocapsid (N) and matrix (M) genes in one reaction (dual target-PCR). The dual target-PCR detected MV RNA in tissue culture fluid containing 1 TCID50 of the MV Loss strain, and was as sensitive as a single target-PCR. Specificity was confirmed by the failure of the dual target-PCR to amplify products from the infected tissue culture containing related paramyxoviruses. Thirty-two of 35 (91.4%) samples collected from 23 patients with confirmed measles infection by the detection of measles specific IgM were found to be positive for MV RNA by PCR. Direct sequencing of the PCR amplicons revealed three different genotypes among the MV strains that were detected in 12 patients. The dual target-PCR method is suitable for the diagnosis of measles infection and, based on the sequencing of the PCR product DNA, for investigating the molecular epidemiology of MV strains.

Adult↗
PubMed1996

Craniometaphyseal and craniodiaphyseal dysplasia, head and neck manifestations and management.

Craniometaphyseal and craniodiaphyseal dysplasia are rare genetic disorders of bone due to modelling errors of long bones and skull bones. These syndromes present with multiple ENT symptomatology from an early age. The diagnostic distinction can now be made radiologically by serial skeletal survey which is important for prognosis. We review the clinical, radiological, computed tomography (CT) scan, otological, audiological and histopathological findings in two cases with craniodiaphyseal, and two cases with craniometaphyseal dysplasia, and report our experiences of medical and surgical treatment to date. In the craniodiaphyseal dysplasia, the hearing abnormality progressed from an initial conductive to a mixed loss on serial audiometric follow up. Temporal bone CT scans showed narrowing of the middle ear cavity, internal auditory meatus, and facial nerve canal at the geniculate ganglion. Benefits from choanal stenosis surgery, craniofacial remodelling and dacrocystorhinostomy were shortlived. Calcitriol therapy with a low calcium diet did not alter the clinical course of progression in our cases. The underlying defect, causing net bone formation in these phenotypically similar syndromes, appears to be different when based on the differing biochemical responses to calcitriol and bone biopsy findings. Increased numbers of osteoblasts were found in bone biopsies from both cases with craniodiaphyseal dysplasia. Early recognition is crucial in these conditions as therapy directed at the underlying bony defect has the best chance of success if initiated in infancy.

Adult↗
PubMed1996

Anxiety and the use of strategies in the performance of a sentence-picture verification task.

An experiment was conducted to examine processing strategy differences in anxiety. The sentence-picture verification task was modified to incorporate a block of threat-related trials (involving a knife and a rifle) and a block of neutral trials (involving a truck and a chair). It was predicted that the high-trait, relative to low-trait, anxious individuals would prefer to use a linguistic strategy for threat-related as compared to neutral trials. In addition, the idea that an image-based strategy is more important for processing emotional material was examined. There was some support for both of these hypotheses.

Adult↗
PubMed1996

The von Restorff effect in rats (Rattus norvegicus).

Two experiments examined the functional equivalence of memory in the rat (Rattus norvegicus) with memory in humans for serially presented items. Memory was assayed with an 8-arm radial maze, in which rats were allowed access to 5 arms of the maze and were then removed. Following a retention interval of 16 min, the rats were replaced in the maze and allowed to retrieve pellets from the 3 unvisited arms. The errors in reentering previously visited arms were noted. Both primacy and recency effects were found as with humans. Presenting a stimulus change after entry to 1 of the maze arms improved recall for that arm relative to when no change occurred. This effect was found using both handling and tone cues, and irrespective of whether the change consisted of presentation or nonpresentation of the cue. These results suggest that rats are subject to a von Restorff-like effect similar to that in humans.

Animals↗
PubMed1996

Does clock-watching make you clockwise?

French and Richards (1993) found that subjects asked to draw from memory a clock that had Roman numerals on its face typically represented the number four on the clock face as "IV" rather than the correct "IIII", whereas those merely asked to copy it typically drew "IIII". The current experiments followed the methodology of French and Richards, but then went on to examine the subsequent memorial representation of the number four. Subjects drew a clock with Roman numerals on its face, either from memory (with or without forewarning) or while the clock remained in full view. Subsequently, subjects were asked to recall the exact form in which the numbers were represented on the clock (Experiment 1) or were asked to recognise which of two clocks had been presented earlier (Experiment 2). Findings supported the idea that subjects in the copy condition were more likely than subjects in other conditions to draw the clock without invoking schematic knowledge of Roman numerals. The basic effect reported by French and Richards was replicated in both experiments. Furthermore, in both experiments, subjects who correctly drew the clock with the number four represented as "IIII" were more likely to misrepresent it as "IV" in the subsequent memory task if they were in the copy condition rather than the two memory conditions. The results are interpreted in terms of schema theory.

England↗
PubMed1996

The gene encoding collagen alpha1(V)(COL5A1) is linked to mixed Ehlers-Danlos syndrome type I/II.

The Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inherited connective tissue disorders in which cutaneous fragility and ligamentous laxity often combine with vascular, gastrointestinal, and skeletal deformities. There is considerable phenotypic overlap between the more common forms of EDS (types I and II), in which specific molecular defects have not yet been identified. Recently, genetic linkage has been demonstrated between the COL5A1 gene, which encodes the alphal chain of type V collagen, and EDS type II in a large British kindred. Using a polymorphic intragenic simple sequence repeat at the COL5A1 locus, we now demonstrate tight linkage to EDS type I/II in a three-generation family, giving a LOD score (log10 of the odds for linkage) of 4.07 at zero recombination. The variation in expression in this family suggests that EDS types I and II are allelic, and the linkage data support the hypothesis that mutation in COL5A1 can cause both phenotypes.

Aged↗
PubMed1996

Hypomania, anxiety and the emotional Stroop.

Bentall & Thompson (1990) selected participants on the basis of high, medium and low scores on the Hypomanic Personality Scale. In an emotional Stroop test, the high hypomanic participants showed interference of colour naming for depression-related but not euphoria-related words. The current study tests the hypothesis that the effects found were mediated by anxiety, and not hypomania as claimed. Bentall & Thompson's study was repeated but measures of state of trait anxiety were also taken. When analysis was restricted to three subgroups selected in the same manner as in Bentall & Thompson's (1990) study, the findings were very similar to those found in that study and the hypomania-related interference effects were found to occur even when anxiety levels were taken into account. Further analyses of data from the full sample of participants supported the idea that hypomanic personality might reflect a partially successful means of coping with depressive tendencies.

Adult↗
PubMed1996

Assessment of the European classification criteria for Sjögren's syndrome in a series of clinically defined cases: results of a prospective multicentre study. The European Study Group on Diagnostic Criteria for Sjögren's Syndrome.

OBJECTIVE: To assess the recently proposed preliminary criteria for the classification of Sjögren's syndrome (SS) in a multicentre European study of a new series of clinically defined cases. METHODS: The criteria included six items: I = ocular symptoms; II = oral symptoms; III = evidence of keratoconjunctivitis sicca; IV = focal sialoadenitis by minor salivary gland biopsy; V = instrumental evidence of salivary gland involvement; VI = presence of autoantibodies. Each centre was asked to provide five patients with primary SS, five with secondary SS, five with connective tissue diseases (CTD) but without SS, and five controls (patients with ocular or oral features that may simulate SS). The preliminary six item classification criteria set was applied to both the SS patients and the non-SS controls, and the performance of the criteria in terms of sensitivity and specificity was tested. RESULTS: The criteria set was tested on a total of 278 cases (157 SS patients and 121 non-SS controls) collected from 16 centres in 10 countries. At least four of the six items in the criteria set (limiting item VI to the presence of Ro(SS-A) or La(SS-B) antibodies) were present in 79 of 81 patients initially classified as having primary SS (sensitivity 97.5%), but in only seven of 121 non-SS controls (specificity 94.2%). When the presence of item I or II plus any two of items III-V of the criteria set was considered as indicative of secondary SS, 97.3% (71 of 73) of the patients initially defined as having this disorder and 91.8% (45 of 49) of the control patients with CTD without SS were correctly classified. CONCLUSION: This prospective study confirmed the high validity and reliability of the classification criteria for SS recently proposed by the European Community Study Group.

Adult↗
PubMed1995

[Loss of trabecular bone strength and bone quality after 5 years of fluoride therapy for osteoporosis].

In order to evaluate the effect of sodium fluoride (NaF) on bone biomechanical competence, iliac crest biopsies were taken before and after one year of treatment in 12 osteoporotic patients, and before and after five years of treatment in 14 patients. Bone fluoride content had increased significantly after both one and five years of treatment, indicating that the administered fluoride had been ingested. After one year of treatment, no difference was observed in iliac crest trabecular bone ash content. A general trend for decreased bone strength and bone quality was observed, but this was insignificant. After five years of fluoride treatment, an insignificant decrease in iliac crest trabecular bone ash content was observed. A significant reduction of 45% was found in trabecular bone strength (p < 0.05), and an even more pronounced reduction of 58% was found in trabecular bone quality (p < 0.01). The results of this study indicate that long-term administration of sodium fluoride may be detrimental to bone quality, at least as measured in non-loaded iliac crest trabecular bone.

Aged↗