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Biomedical subjects

J S MacDonald

Publications and source records attributed to J S MacDonald.

69 records · Page 4Linked to original sources
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

Computerised axial tomography for diagnosis of pancreatic cancer.

Computerised axial tomography demonstrated the presence of a mass lesion in the pancreas in 9 (64%) of 14 patients with histologically confirmed pancreatic cancer. Since this was a retrospective analysis, the percentage of false positive and negative results using this technique is not as yet known. The technique appears accurate in detecting abnormal pancreatic masses of 10 cm in diameter or more, however, for masses less than 10 cm in diameter the yield at present is only 33%. With further technical refinement to increase resolution, the automatic computerised transverse axial scan should prove to be an invaluable procedure for the detection of pancreatic carcinoma, in designing radiation therapy ports, and in providing objective information regarding response of therapy and progression of disease.

Adenocarcinoma↗
PubMed1976

The value of lymphography in the management of bladder cancer.

228 bilateral pedal lymphograms in patients with bladder cancer have been correlated with the features of the primary bladder tumour and patient survival. In 70 cases, radiographic findings were correlated with operative node histology. The results show that it is not possible to predict accurately which cases have lymphatic spread without this investigation. Positive lymphograms were found in 91 cases, and were associated with a very poor prognosis. Only 6% of patients with unilaterally involved iliac nodes survived 5 years, and all patients with bilateral iliac or para-aortic disease died within 3 years. Histological correlation was found in 90% of cases, and the results indicate that this investigation slightly underestimates the incidence and extent of microscopic lymphatic metastases. It is concluded that this investigation is essential in planning the treatment of infiltrating bladder tumours.

Follow-Up Studies↗
PubMed1975

Chemotherapy of large intestinal carcinoma. Current results and future prospects.

Chemotherapy of advanced stages of large bowel cancer has until recently made little progress since the introduction of 5-FU 16 years ago. While survival is improved for patients who respond, 5-FU alone has made little impact on life span of the overall population of patients. Mitomycin-C and the chloroethyl nitrosourea antitumor agents, and in particular methyl-CCNU, have also demonstrated marginal activity in large bowel cancer. Two recently reported controlled clinical trials of combination chemotherapy have demonstrated response rates that are substantially better than those obtained with 5-FU alone; a 43% response rate in colorectal carcinoma has been reported using a combination of 5-FU, BCNU, vincristine, and DTIC, compared to a 25% response with 5-FU as a single agent; a 44% objective response rate with a combination of 5-FU, methyl-CCNU, and vincristine has been reported to be significantly better than 5-FU alone. 5-FU as an adjuvant following surgical resection with curative intent has not prevented tumor relapse; however, it is hoped that future studies employing more effective drug combinations will result in increased number of patients achieving disease free survival.

Administration, Oral↗
PubMed1975

A review of the role of lymphography in the management of testicular tumours.

The pedal lymphographic findings in 260 patients with testicular tumours are reviewed: 117 patients had a seminoma, 105 had a teratoma and 38 combined tumours. 26 percent of seminomas were associated with a positive lymphogram, corresponding figures being 42 percent for teratomas and 53 percent for combined tumours. The role of the lymphogram is (1) to stage the case so that the extent and form of the treatment can be logically assessed, (2) to plan accurately radiotherapy treatment fields, (3) to observe the results of treatment on serial follow-up films, (4) to detect the recurrence of tumour using "re-fill" lymphography if necessary, (5) to show possible unsuspected metastases involving supraclavicular and mediastinal glands, and (6) to give a prognosis, since a negative lymphogram suggests an excellent chance of survival. Three main types of lymphographic appearances are recognized: nodal, mass replacement and "pseudo-lymphomatous". Nodal deposits are most common. Most positive findings are in the para-aortic chain on the same side as the tumour. Iliac involvement is much less common. Seminomas in this series showed a 96 percent crude three-year survival rate. For teratomas and combined tumours the three-year survival rates were 59 percent and 61 percent respectively, but deaths are uncommon in the lymphographically negative Stage I cases. Bone deposits are rare. Only two were found in this series. We do not perform testicular lymphography, but consider there is a useful role for inferior venacavography when there is poor filling of upper para-aortic nodes at lymphography. The importance of taking follow-up films after the initial examination is stressed.

Bone Neoplasms↗
PubMedDate not supplied

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase induce reductase accumulation and altered lamellar bodies in rat forestomach keratinocytes.

Lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and a potent hypocholesterolemic agent, induces a hyperplastic thickening of the rat forestomach mucosa after oral administration of its active form, a hydroxyacid. We studied the effects of lovastatin on the intracellular accumulation of HMG-CoA reductase immunostaining and the accompanying morphological changes in rat forestomach keratinocytes by immunofluorescence microscopy and transmission electron microscopy (TEM). Administration of lovastatin hydroxyacid induced increases in HMG-CoA reductase levels within forestomach keratinocytes that were dose and time dependent and reversible. The adjacent glandular stomach epithelium did not exhibit induction of reductase. A pharmacologically inactive epimer of lovastatin hydroxyacid did not increase keratinocyte reductase accumulation, and lovastatin lactone induced minimal forestomach reductase. TEM of forestomachs from rats given lovastatin hydroxyacid demonstrated profound alterations in epidermal lamellar bodies (organelles that transport lipids and steroids to the intercellular spaces of the stratum corneum). Treated cells lacked internal lipid lamellae and failed to secrete sheets of lipid material into the intercellular spaces of the stratum corneum. We hypothesize that sustained inhibition of HMG-CoA reductase in rat forestomach keratinocytes induces accumulation of HMG-CoA reductase and hyperplasia by inhibiting sterol synthesis, assembly of lamellar bodies, and formation of intercellular lipid sheets.

Animals↗
PubMedDate not supplied

Toxicokinetic and mechanistic considerations in the interpretation of the rodent bioassay.

When chemicals that are nongenotoxic in conventional assays produce increases in tumor incidence in rodents in chronic bioassays, the determination of the significance of these data for human safety is a challenging task. An important first step in this process is consideration of available data on the mechanism of action and biological properties of the chemical as well as pharmacokinetic and metabolism data in the species showing the response. In recent years, there has been an increase in the understanding of so-called "secondary mechanisms" of carcinogenesis (e.g., thyroid tumors in rats following exposure to enzyme inducers). Application of these data may assist in determination of human risk. There are 2 important questions that will be explored and developed: Are there biological effects produced in the test species that could explain the increase in tumor incidence, and will these effects be reproduced in humans? What is the exposure to the chemical that is associated with the increase in tumors, and how does this relate to exposure in humans?

Animals↗