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Biomedical subjects

C A Parsons

Publications and source records attributed to C A Parsons.

At least 37 records · Page 2Linked to original sources
PubMed1989

Reformatted computed tomography of the female pelvis: normal anatomy.

Axial computed tomography (CT) of the pelvis provides useful information in patients with gynaecological malignancies, both for initial staging, to follow disease progression and to assess response to treatment. Additional useful information may be available from reformatted coronal and sagittal images. Knowledge of normal anatomy is essential for correct interpretation of pathology. The anatomy and technique used to acquire the images are described in this paper.

Cervix Uteri↗
PubMed1988

Resolution of model Holliday junctions by yeast endonuclease is dependent upon homologous DNA sequences.

Holliday junctions, in which two double-stranded DNA molecules are linked by single-stranded crossovers, are thought to be central intermediates in genetic recombination. We report here the in vitro specificity of a yeast endonuclease for structures analogous to Holliday junctions. Plasmids that extrude inverted repeat sequences into cruciform junctions are cleaved by the introduction of nicks into strands of like polarity, approximately 4-8 nucleotides from the base of the junction. In all cases, cleavage occurs within homologous sequences, and with precise symmetry across the junction. In contrast, a junction containing four arms of unrelated sequence is cleaved asymmetrically. The dependence upon homology for symmetrical cleavage is not found with T4 endonuclease VII, which cleaves branched structures in vitro. Holliday junction resolution appears to occur in a concerted manner by the introduction of nicks into two homologous DNA helices held in alignment.

Base Sequence↗
PubMed1988

The accuracy of mammography alone and in combination with clinical examination and cytology in the detection of breast cancer.

The accuracy of mammography alone and in combination with clinical examination and aspiration cytology was assessed in 402 patients who attended the Early Diagnostic Unit of the Royal Marsden Hospital, London. The sensitivities of mammography, clinical examination and cytology in identifying breast cancer were 76.9%, 81.7% and 63.5% respectively; the specificities of each test were 90.0%, 87.6% and 99.3%. The calculated sensitivity was increased to 96.2% if one positive test out of the three was regarded as an indication to undertake breast biopsy. If this approach was adopted the number of breast cancers missed would be two out of 104 and the yield of positive biopsies would be approximately one in four (27.6%). The implications of proceeding to breast biopsy on the basis of a single positive test are discussed.

Aged↗
PubMed1988

A quantitative analysis of the spatial relationships of grouped microcalcifications demonstrated on xeromammography in benign and malignant breast disease.

The mammograms of 444 patients who had a breast biopsy leading to a definitive histological diagnosis were reviewed. In 21 cases (4.7%) grouped microcalcifications were identified as the only mammographic abnormality. These groups of microcalcifications were analysed to determine whether there was any quantitative difference between benign and malignant lesions with respect to a shape parameter of the group, the spatial frequency of the particles and neighbour-to-neighbour relationships of the particles. This analysis did not reveal any significant difference between the spatial relationships of the grouped microcalcifications found in benign and malignant breast disease.

Biopsy↗
PubMed1987

Purification and properties of a nuclease from Saccharomyces cerevisiae that cleaves DNA at cruciform junctions.

An endonuclease specific for cruciform junctions has been purified from yeast cells treated with a DNA-damaging agent. The activity was followed through five chromatographic steps by assaying for the linearization of supercoiled plasmid DNA, which extrudes cruciform structures in vitro. The sites of cleavage on pColIR215 were sequenced, and nicks were located to positions symmetrically opposed across the cruciform junction. The products of cleavage were unit length linear duplexes that contained terminal hairpin loops. In contrast to pColIR215, the cleavage patterns of pXG540 plasmid DNA were found to be complex, and cuts were found up to 40 bases from an (A-T)34 sequence that extrudes into a cruciform. Little or no activity could be detected on single-stranded DNA, linear duplex DNA, or nicked circular duplex DNA. The nuclease was insensitive to RNase but was inactivated by treatment with proteinase K. Mg2+ was required as cofactor and could not be replaced by Mn2+, Ca2+, Co2+, or Cu2+. The native molecular weight of the activity was approximately 200,000 as estimated by gel filtration.

DNA Damage↗
PubMed1983

High-dose alkylation therapy using ifosfamide infusion with mesna in the treatment of adult advanced soft-tissue sarcoma.

In a phase II study, 42 patients with advanced soft-tissue sarcoma were treated with ifosfamide by 24-h infusion and mesna by 4-h IV bolus, repeated every 3 weeks. Ten patients received ifosfamide 5.0 g/m2, 20 had the dosage increased to 8.0 g/m2, and 12 received 8.0 g/m2 from the outset. Mesna was given in doses of 400 mg/m2 or 600 mg/m2. Of 40 patients evaluable for response, six (15%) achieved complete response and nine (23%) partial response. The overall response rate was 38%. The median duration of response was 11 months. Treatment was associated with falls in peripheral WBC and alopecia in all patients. Most experienced severe nausea and vomiting. In seven nephrotoxicity developed, and two of these died of renal failure. Renal tubular defects and cerebral effects also occurred. Mesna largely prevented haemorrhagic cystitis. Ifosfamide offers a new alternative to previous chemotherapy for advanced soft-tissue sarcoma, but alterations in dose or method will be necessary to reduce toxicity.

Adolescent↗
PubMed1983

Aminoglutethimide for the treatment of advanced postmenopausal breast cancer.

Two hundred and thirteen unselected postmenopausal women with advanced breast cancer were treated with aminoglutethimide and hydrocortisone. There were 6 complete responses (CR), 47 partial responses (PR), 25 stable disease (SD) and 3 mixed response. Overall objective response rate was 28%, and with SD 41%. Median duration of objective response was 14 months. Years after menopause, age and tumour-free interval did not affect response rates. Main side-effects were drowsiness and lethargy (33%), rash (23%) and nausea (15%). Eleven patients (5%) stopped treatment because of toxicity. Median survival from start of treatment was 28 months and was the same for CRs, PRs and SD, compared with 10 months for progressive disease (P less than 0.001). Median survival from first metastasis was 43 months for PR/CR, 40 months for SD (not significantly different) and 22 months for progressive disease (P less than 0.001). Aminoglutethimide is an effective endocrine therapy in advanced postmenopausal breast cancer, particularly for bone deposits. Disease stabilization is associated with symptomatic and survival benefit similar to CR/PR.

Adult↗
PubMed1981

Tamoxifen versus aminoglutethimide in advanced breast carcinoma: a randomized cross-over trial.

Altogether 117 patients with advanced breast cancer were treated with either tamoxifen 10 mg by mouth twice daily or aminoglutethimide 250 mg by mouth four times daily with hydrocortisone 20 mg twice daily in a randomised cross-over trial in which patients who failed to respond to the first treatment or relapsed while receiving it were switched to the other. Eighteen (30%) out of 60 patients initially treated with tamoxifen achieved an objective response and 11 (18%) showed stable disease. Seventeen (30%) out of 57 patients treated initially with aminoglutethimide achieved an objective response and 13 (23%) achieved stable disease. Objective responses in bone metastases were achieved more commonly with aminoglutethimide (11 patients (35%)) than with tamoxifen (five (17%)). The predicted median duration of response for tamoxifen was 15 months and for aminoglutethimide over 15 months (no significant difference). Five (15%) out of 34 patients who failed to respond to tamoxifen and four out of six patients who relapsed after responding to tamoxifen subsequently responded to aminoglutethimide. In contrast, only two (6%) out of 31 patients who failed to respond to aminoglutethimide and none out of four patients who relapsed while receiving aminoglutethimide subsequently responded to tamoxifen. The main side effects occurring in the 97 patients who received aminoglutethimide as first- or second-line treatment were lethargy and drowsiness (36 patients) and rash (29); seven patients had to stop treatment because of side effects. In contrast, side effects were rare and mild with tamoxifen and no patient had to stop treatment because of them. Both tamoxifen and aminoglutethimide appeared from this study to be equally effective in the medical endocrine treatment of advanced breast cancer.

Adult↗
PubMed1980

The role of computed tomography in tumours of the larynx.

A clinical study of computed tomography (CT) was undertaken in 35 patients with tumours involving the larynx. Twenty-seven had primary laryngeal neoplasms, five had tumours arising in adjacent structures but invading the larynx and three who had undergone total laryngectomy were investigated for possible recurrence. The findings were compared with conventional radiological methods and clinical assessment. Confirmation was obtained from laryngectomy specimens in four patients and at autopsy in one. CT provided additional preoperative information on 14 occasions. This included better delineation of submucosal tumour extent, invasion of the pre-epiglottic space and cartilage displacement in invasion.

Humans↗
PubMed1980

The use of computed tomography in recurrent rectal tumors.

Thirty-six patients treated surgically for carcinoma of the rectum were examined by computed tomography (CT) to determine its value in investigating local pelvic recurrence. Thirteen patients with suspected recurrence but no clinical or radiological evidence of disease and 19 patients with known recurrence were scanned. This study indicates that CT is effective for diagnosing local recurrence from carcinoma of the rectum and accurately delineates the extent of tumor spread, as well as organ and muscle involvement. The value of CT for screening patients at high risk of developing pelvic recurrence is discussed.

Adenocarcinoma↗
PubMed1977

Lymphography in alveolar soft part sarcoma.

Alveolar soft part sarcoma is a rare tumour found in musculofasculofascial planes, most often in the lower limbs of young adults. The tumour shows a characteristic orderly cellular arrangement and the few mitoses belie the often rapid progress of the disease. Cytoplasmic crystals unique to this tumour may be demonstrated. The need for thorough investigation of the patient as an initial staging procedure and to provide a prognostic forecast is emphasised. Isotope scanning of the bones, brain and liver is indicated. Two cases are reported which demonstrate the value of lymphography. The nodal features found were: 1. Enlargement of a lymph node of normal interal architecture. 2. Almost complete nodal replacement by tumour. 3. Pseudolymphomatous appearances. Follow up films are required, after an interval, to show the progress of the disease or response to therapy.

Adult↗
PubMed1976

The pulmonary capillary bed after lymphography.

A small series of patients underwent radio-isotope lung scanning before and after the bipedal injection of oily contrast medium for abdominal lymphography to assess known malignant disease. After lymphography the lung scans showed an increase of between 12 and 100% in the radioactivity recorded over the anterior chest. No change was recorded over the posterior aspect of the chest. It is suggested that the increase is a result of blockage of posteriorly placed pulmonary capillaries and diversion of blood flow to the anterior segments.

Contrast Media↗