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Biomedical subjects

R Lawson

Publications and source records attributed to R Lawson.

At least 37 records · Page 2Linked to original sources
PubMed1995

The effects of calcitonin on serum calcium levels in immature brown trout, Salmo trutta.

Salmon calcitonin was administered intraperitoneally (0.1, 10, 1000 ng/100 g of fish) to freshwater-adapted, immature, female brown trout, Salmo trutta, and changes in serum calcium levels were determined. The lowest dose (0.1 ng) had an effect similar to injection of saline (control), but the higher doses produced hypercalcemia. These latter effects were associated with increased serum levels of calcitonin. Maintaining immature brown trout in waters containing 20 and 50 mM calcium chloride resulted in a significant lowering of serum calcitonin with time although serum calcium levels remained stable. The extent of the decrease in serum calcitonin increased with the higher levels of environmental calcium.

Aging↗
PubMed1994

Object recognition under sequential viewing conditions: evidence for viewpoint-specific recognition procedures.

In many computational approaches to vision it has been emphasised that object recognition involves the encoding of view-independent descriptions prior to matching to a stored object model, thus enabling objects to be identified across different retinal projections. In contrast, neurophysiological studies suggest that image descriptions are matched to less abstract, view-specific representations, resulting in more efficient access to stored object knowledge for objects presented from a view similar to a stored viewpoint. Evidence favouring a primary role for view-specific object descriptions in object recognition is reported. In a series of experiments employing line drawings of familiar objects, the effects of depth rotation upon the efficiency of object recognition were investigated. Subjects were required to identify an object from a sequence of very briefly presented pictures. The results suggested that object recognition is based upon the matching of image descriptions to view-specific stored representations, and that priming effects under sequential viewing conditions are strongly influenced by the visual similarity of different views of objects.

Adolescent↗
PubMed1994

Substance P: an immunohistochemical and biochemical study in human gingival tissues. A role for neurogenic inflammation?

Substance P has been studied in relation to its distribution within gingival tissues as well as its effect on cultured human gingival fibroblasts. The tissue distribution was varied depending on the degree of inflammation present. In healthy tissues substance P was found in the connective tissues interspersed between the collagenous elements and was particularly prominent in the areas immediately subjacent to the epithelial rete pegs. In inflamed tissues, substance P was markedly increased particularly around the blood vessels as well as in close association with much of the inflammatory cell infiltrate. The effect of substance P on human gingival fibroblast proliferation was monitored by [3H]-thymidine incorporation and indicated substance P to be mitogenic for these cells at low concentrations (1 x 10(-9) M) and tended towards an inhibitory effect at higher concentrations (1 x 10(-4) M). Substance P did not have any effect on the release of either total proteins or proteoglycans into the culture medium. However, exposure of the cells to substance P did cause a greater accumulation of both total protein and proteoglycan with the cell layer material. These findings suggest a potential role for substance P on gingival tissues and in particular their resident fibroblastic cells and can therefore be used as a basis for more detailed studies into the relationship between neuropeptide release associated with neurogenic inflammation and periodontal pathology.

Analysis of Variance↗
PubMed1994

Day-case laparoscopy revisited: have post-operative morbidity and patient acceptance improved?

Previous studies of day-case laparoscopy have indicated considerable post-operative morbidity, with high incidences of nausea, vomiting and pain, often resulting in overnight admission. These studies also indicate that 30% of patients would have preferred an overnight stay. Changes in day surgery anaesthetic practice since then have included the wider use of non-steroidal analgesics and the specific use of propofol, a new short acting anaesthetic drug, with improved recovery and anti-emetic properties. We audited 74 patients who had day-case laparoscopy for diagnosis or sterilisation, and found that the incidence of nausea and vomiting was lower than any previously recorded, and mean pain scores were minimal. No patient was admitted for recovery problems, despite the inclusion of afternoon procedures; two patients only were admitted for surgical complications. Despite considerable morbidity after their return home, only 8% of patients said they would have preferred an overnight stay. Changes in anaesthetic practice would seem to make day-case laparoscopy a more acceptable procedure than previously reported.

Adult↗
PubMed1993

The effects of short courses in modifying the attitudes of adult and adolescent stutterers to communication.

Two studies examined attitude changes to communication by stutterers during short intensive courses. The Perceptions of Stuttering Inventory was used to monitor change. As the experimental hypothesis anticipated, change was most clearly seen in the avoidance items of the inventory. In both studies these showed significantly greater positive change than either the struggle or expectancy items. Moreover, positive changes were only found during the period of the course; no positive changes were found for any scales during the month prior to or after the course. The findings justified the use of short courses to change the attitudes of stutterers and suggested that they may be used in conjunction with other approaches which seek to influence fluency directly. An attempt to relate the changes in attitude to changes in speech over the short period of the course was unsuccessful.

Adolescent↗
PubMed1993

Polymerase chain reaction analysis of allele frequency and loss at the Harvey ras locus in myeloid malignancies.

The hypothesis that 'rare' variable number tandem repeat (VNTR) alleles of the Harvey ras (Ha-ras) locus are an inherited predisposing factor in myeloid malignancies has been evaluated. We describe an application of the polymerase chain reaction (PCR) which amplifies the VNTR region at the Ha-ras locus and offers a number of advantages over conventional Southern analysis. Ha-ras VNTR genotypes were assigned to 57 normal subjects, 46 patients with acute myeloid leukaemia (AML), 26 with myelodysplastic syndrome (MDS) and 49 with chronic granulocytic leukaemia (CGL). By comparison with previous reports we found significantly higher frequencies of rare alleles (20.2%) in our normal subjects of whom more than 35% had at least one 'rare' allele. The frequencies of rare alleles in the patient groups was not significantly different from the normal group (chi 2 = 0.54, p = 0.91). In studies of constitutional and leukaemic DNA from patients with AML, we found that allelic loss at the Ha-ras locus was not a common phenomenon. The improved resolution achievable with PCR compared with Southern analysis was demonstrated by the inability of Southern analysis to resolve six out of 34 PCR heterozygotes. We therefore suggest that previous studies showing linkage between rare Ha-ras alleles and susceptibility to malignancy should be reevaluated using our sensitive PCR technique.

Acute Disease↗
PubMed1992

The effect of plain packages on the perception of cigarette health warnings.

A survey was conducted with 568 adolescent children (average age 13) to investigate the possible effects upon perceptions of health warnings when cigarettes are presented in plain packaging. A measure of unaided recall was used to reflect participants' attention to the assortment of cues presented on cigarette packs. The presentation of health warnings in the context of plain packs achieved a significantly greater recall rate as opposed to brand packs. When less brand image cues were presented, respondents were able to perceive and recall with more accuracy a greater proportion of 'non-image' information.

Adolescent↗
PubMed1992

A late complication of pectus excavatum repair.

We report a late complication of pectus excavatum repair which highlights the importance of a chest X-ray in evaluating chest pain in patients who have had previous chest surgery. It also raises the question of whether or not implanted wires should be electively removed following bony union.

Adult↗
PubMed1992

Nephrotic-range proteinuria associated with right atrial myxoma.

A case of right atrial myxoma presenting with right heart failure and proteinuria is described. Proteinuria was variable and this corresponded with the degree of systemic venous congestion. On one occasion the proteinuria was within the nephrotic range. There was no evidence of intrinsic renal pathology. The right heart failure and proteinuria resolved after tumour removal, suggesting that the etiology of urinary protein loss was a reversible increase in glomerular permeability.

Aged↗
PubMed1990

Semi-automatic quantification of regional cerebral perfusion in primary degenerative dementia using 99m technetium-hexamethylpropylene amine oxime and single photon emission tomography.

A new semi-automatic method for quantifying regional cerebral uptake of 99m technetium-hexamethylpropylene amine oxime (99mTc-HMPAO) was used to assess single photon emission tomograms from 5 normal subjects, 14 patients with Alzheimer's disease, 14 patients with dementia of frontal lobe type and 4 patients with dementia with motor neurone disease. Uptake in both posterior cortical regions, although not in other regions, was significantly lower (P less than 0.05) in Alzheimer's disease than in normal controls. Conversely in both dementia of frontal lobe type and dementia with motor neurone disease, uptake was significantly reduced (P less than 0.05) compared with controls in all anterior cortical regions but not in posterior regions. Numerical findings in each disease mirrored the pattern of reduced tracer uptake previously reported by visual assessment. Nine patients were re-examined after an interval of at least 1 year. Comparison of follow-up scans with original images showed significant decreases in mid-anterior, left anterior and left posterior cortical uptake (P less than 0.01) in patients with Alzheimer's disease and in left middle, left posterior and right posterior cortical uptake (P less than 0.01) in patients with dementia of frontal lobe type. The method of quantification may be a useful adjunct to the visual assessment of single photon emission tomograms.

Alzheimer Disease↗
PubMed1990

Simian virus 40 large T-antigen-dependent DNA replication is activated by protein phosphatase 2A in vitro.

The simian virus 40 large T antigen (T) is a multifunctional phosphoprotein. We found that T-dependent simian virus 40 DNA replication is substantially inhibited by okadaic acid. This result suggests that DNA replication is activated by dephosphorylation in vitro. We show here that the target activated by dephosphorylation, which stimulates DNA replication, is T and that the phosphatase involved is protein phosphatase 2A.

Alkaline Phosphatase↗
PubMed1990

PaperChase: a user-friendly program for searching the biomedical literature.

PaperChase is a computer program which provides an efficient interface to the National Library of Medicine's MEDLINE database of references to the biomedical literature. The database includes references (citations) and abstracts compiled from Index Medicus, the International Nursing Index and the Index to Dental Literature. PaperChase may be accessed using any computer terminal or personal computer with modem. No special knowledge of computers or biomedical terms is necessary. Simple menus enable the novice to search the biomedical literature without training. A command language speeds searching for the experienced user. PaperChase does not require the user to know the database's indexing terminology, called Medical Subject Headings. Everyday language may be used and PaperChase will translate, or "map", the user's search term into the required Medical Subject Heading. PaperChase monitors a search in progress and suggests additional Medical Subject Headings which can be used to broaden or narrow a search. The searcher can order a full-text photocopy of any reference found in PaperChase. Support documentation and a subscriber newsletter are provided at no charge. Trained search specialists are available to offer assistance and to answer questions.

MEDLARS↗
PubMed1989

Etoposide combined with cyclophosphamide plus vincristine compared with doxorubicin plus cyclophosphamide plus vincristine and with high-dose cyclophosphamide plus vincristine in the treatment of small-cell carcinoma of the lung: a randomized trial of the Bristol Lung Cancer Study Group.

A total of 353 patients with previously untreated small-cell lung cancer (SCLC) were accrued in this multicenter trial. Patients were randomly assigned to receive one of the following three regimens: cyclophosphamide 1,000 mg/m2 intravenously (IV) day 1, vincristine 1.4 mg/m2 IV day 1, and etoposide 50 mg/m2 IV day 1, followed by etoposide 100 mg/m2/day orally days 2 through 5 (CEV); cyclophosphamide 1,000 mg/m2 IV day 1, vincristine 1.4 mg/m2 IV day 1, and doxorubicin 50 mg/m2 IV day 1 (CAV); cyclophosphamide 2,000 mg/m2 day 1 and vincristine 1.4 mg/m2 IV day 1 (CV). Cycles were repeated every 3 weeks. Treatment groups were comparable with respect to extent of disease, age, sex, performance status, and metastatic sites. No significant differences in response rates, response duration, or survival could be detected in limited disease, although there appeared to be a trend favoring CEV. Among extensive-disease patients, response duration on the CEV regimen was longer than on the CV regimen or the CAV program (P less than .001). The superiority of the CEV regimen was also demonstrated in the survival analysis in which differences attained statistical significance (P = .01). In this group the median survival was increased from 29 weeks on CV to 31 weeks on CAV and 39 weeks on CEV. Myelosuppression was the most frequent toxicity. It was more severe with CV than CEV or CAV. Most nonhematologic side effects were comparable among the three treatment groups. However, the high doses of cyclophosphamide in the CV regimen produced a higher incidence of hemorrhagic cystitis than in the CEV or CAV programs (P less than .001). Cardiotoxicity only occurred in the CAV group (P = .05). The addition of etoposide to the CV regimen resulted in significantly longer response duration and survival without increased toxicity. Similarly, the substitution of etoposide for the doxorubicin in the CAV regimen was associated with prolonged survival and reduced cardiotoxicity.

Adult↗