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Biomedical subjects

J R McLaren

Publications and source records attributed to J R McLaren.

At least 19 recordsLinked to original sources
PubMed1986

Ewing's sarcoma of a lower extremity in an infant. A therapeutic dilemma.

A 5.5-month-old infant with Ewing's sarcoma of the left femur is described. The clinical and the pathologic features in this infant are presented in detail, and the dilemma faced in diagnosis and therapy of Ewing's sarcoma in infants is discussed. It is suggested that Ewing's sarcoma in an infant with a lower extremity lesion may be adequately managed without primary amputation.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1981

The influence of bone on temperature patterns produced by 434-MHz electromagnetic radiation.

The temperature pattern produced in phantoms containing simulated bone and muscle components was determined for 434-MHz electromagnetic radiation. A parallelepiped phantom was employed in this study and heating was conducted for 15 minutes using a commercially available diathermy unit. Both slab and cylindrical bone geometries were investigated, as well as the influence of depth in muscle of the bone component on the resulting temperature pattern. The temperature perturbation produced by bone irradiated by 434-MHz radiation was found to vary drastically with the bone geometry, as well as with the depth of the bone in muscle.

Body Temperature↗
PubMed1979

Small electron beams in radiation therapy.

The use of lead cutouts to produce small beams in electron therapy results in a reduced dose to the patient. The authors investigated this effect for beams with energies less than 8 MeV and diameters of 3 cm or less. Dose measurements were obtained using film and an ionization chamber. Based on these values, corrections were established to account for dose reduction due to cutout spaces and air spaces between the end of the electron cone and the skin surface. Data were also obtained on the dose increase due to backscattering from internal eyeshields.

Electrons↗
PubMed1979

The effect of bone on dose distributions produced by the Fermi National Laboratory fast-neutron beam.

The dose distortion produced by bone during fast-neutron therapy was studied using a target-to-skin distance of 153 cm, with beams 10 x 10 field size at the surface of a phantom. Doses were measured using several muscle-equivalent ionization chambers in the phantom. Results showed that the dose was reduced by interposing bone-equivalent material between the point in question and the surface of the phantom.

Bone and Bones↗
PubMed1978

Effects of combined immunotherapy with levamisole and Bacillus Calmette-Guérin on immunocompetence of patients with squamous cell carcinoma of the cervix, head and neck, and lung undergoing radiation therapy.

Patients with squamous cell carcinoma of the head and neck, squamous cell carcinoma of the cervix, and lung carcinoma were treated with radiation therapy (RT) prior to being randomly assigned either to a group receiving no further treatment or to a group treated with combined adjuvant immunotherapy (bacillus Calmette-Guérin and levamisole). A battery of in vitro immunologic evaluations in addition to skin tests was used to evaluate these patients prior to RT, immediately following RT, and at regular intervals thereafter. Mean percentages and levels of circulating T lymphocytes were significantly lower in all three types of patients prior to RT than in normal healthy controls. B-lymphocyte percentages and levels, however, were not significantly different from controls except for lower B-cell levels in the lung group. Following completion of RT, circulating levels of both T and B lymphocytes were significantly lower than pretreatment values although the percentages were not significantly changed. Mitogenic responses of patient lymphocytes to both phytohemagglutinin and pokeweed mitogen were significantly lower prior to RT than were healthy control responses. A further depression of blastogenesis following RT was statistically significant. Preliminary data at intervals following RT indicate a gradual recovery of depressed immune parameters (T- and B-lymphocyte levels and mitogenic responses) both in patients treated with adjuvant immunotherapy and in those receiving no further treatment. Although not statistically significant in preliminary data, there is a suggestion that recovery of these immune parameters is slower in the group receiving immunotherapy. Plasma sialic acid levels were elevated in patients when compared to healthy controls and remained elevated throughout the study with little fluctuation. Lymphocyte cytotoxic activity against tumor target cells was variably affected by RT, but was generally increased at 8 weeks following RT when compared to previous values.

B-Lymphocytes↗
PubMed1978

Cytological and quantitative cytochemical studies of post-radiation dysplasia.

A total of 60 vaginal smears from 19 women treated with ionizing radiation for malignancies of the genital tract in the past seven years in the Division of Radiation Therapy of Emory University School of Medicine were studied for the presence of post-radiation dysplasia (PRD) by means of Feulgen cytospectrophotometry and cytological analysis. PRD was diagnosed on the basis of the presence of dysplastic cytological changes, absence of clinically detectable lesions, and presence of aneuploid DNA values in the dysplastic cells. PRD was detected in 21% of the studied cases. Uniform criteria for PRD, describing premalignant and malignant post-radiation lesions, diagnosed on the basis of aneuploid DNA values, as well as cytological observations is suggested.

Adult↗
PubMed1977

The influence of bone on 45 MV photon dose distributions.

In an attempt to assess the pertubation of 45 MV depth dose distribution in a water phantom equipped with various thicknesses of bone-equivalent plastic. An increased dose was observed immediately behind the bone material and a reduced dose was found for points located greater than 5 cm behind the bone-equivalent plastic. The most significant change of the depth dose curve was produced by bone located in the dose build-up region.

Bone and Bones↗
PubMed1977

Cytochemical and immunologic of women treated for squamous cell carcinoma of the cervix.

A total of 126 individuals were tested for circulating T lymphocyte levels: 10 patients with stage I-III squamous cell carcinoma of the cervix before treatment; 65 women previously treated with radiation for stage I and II squamous cell carcinoma of the cervix; and 51 healthy age-matched controls. Percentages of aneuploid cells and DNA content in vaginal or cervical smears were determined in 94 patients. All patients with squamous cell carcinoma of the cervix had lower ratios and levels of circulating T lymphocytes than healthy controls. Cytologic and cytochemical DNA studies of vaginal and cervical smears revealed that these individuals had high percentages of aneuploid cells in cervical smears as well as high DNA values. Patients with no evidence of dysplasia had increased circulating T lymphocyte levels compared to pretreatment values, a lower number of aneuploid cells, and mean DNA values close to diploid cells. Based on cytologic and quantitative DNA studies of vaginal and cervical smears, postirradiation dysplasia was diagnosed in 17 of 65 women previously treated by radiation for squamous cell carcinoma of the cervix. No difference in the levels of circulating T lymphocytes between women with postirradiation dysplasia and women without this mucosal disorder and no evidence of cancer was found.

Adult↗
PubMed1977

Sequelae of abdominal radiation and their medical management.

As various chemotherapeutic agents are added to treatment routines, the possibility of adverse effects is appreciably increased, particularly in those organs for which the agents have specific toxicity. Symptoms most commonly associated with radiation sickness, such as malaise, anorexia, nausea, vomiting, diarrhea, dysphagia, dermatitis, and depleted hemopoietic elements, are usually seen late in the course of radiation therapy or shortly thereafter. Consequently, they are managed by the physician in charge of radiation or the patient's referring physician. The general physician may be concerned with symptoms arising from delayed organ pathology. These symptoms may arise in many tissues that are still considered somewhat radioresistant, but secondary to sequelae arising because of connective tissue changes from obliterative narrowing of the finer vasculature. Radiation may be only one of several possible causes, and the symptoms of sequelae may appear only after a long latent period, so that the previous radiation may not be considered in the differential diagnosis unless a detailed history is taken. The medical management of these sequelae is, in general, similar to that used for the pathology produced in these organs by other agents.

Abdominal Neoplasms↗
PubMed1976

Immunocompetence of patients with bronchogenic carcinoma.

Patients with lung carcinoma were tested for number of circulating thymus-derived (T-)lymphocytes and lymphocyte cytotoxicity before treatment and following operation or radiation therapy or a combination of the two. The proportion of circulating T-lymphocytes in healthy individuals was 75%, and the T-lymphocyte level was 1, 460 per cubic millimeter. All patients with lung cancer had a significantly decreased percentage and absolute number of T-cells before any treatment. Patients tested six to eight weeks following pneumonectomy or lobectomy showed an increased proportion of circulating T-cells in comparison to pretreatment values. Functional activity of immune lymphocytes as shown by cytotoxicity assay also improved in comparison to pretreatment values. The potential value of tests for immunocompetence is discussed.

Adenocarcinoma↗
PubMed1975

Short term effects of ionizing radiation on the recurrent or metastatic skin cancer--a quantitative DNA study.

A total of 72 smears from two cases of metastatic squamous cell carcinoma of the head and neck during radiation therapy were studied for DNA content. The percentage of aneuploid tumor cells in the range of lower ploidy was high in both cases and remained high throughout the treatment. The correlation between the percentage of aneuploid cells in metastatic squamous cell carcinoma and radiocurability of these lesions has been discussed.

Aged↗