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Biomedical subjects

J M Seddon

Publications and source records attributed to J M Seddon.

At least 145 records · Page 8Linked to original sources
PubMed1984

Development of additional primary tumors after 62 years in the first patient with retinoblastoma cured by radiation therapy.

In the first well-documented case of bilateral retinoblastoma to be cured by X-irradiation of the nonenucleated eye, a basal cell carcinoma and then a squamous cell carcinoma of the eyelids developed 60 years after the original treatment. The patient, a 66-year-old man, had been treated by Verhoeff between 1917 and 1919. These new tumors may have been examples of second primary tumors, found in about 0.5% to 2.5% of patients with bilateral retinoblastoma, or they may have been coincidental. Because of the 60-year period between the patient's original treatment and the development of these tumors, it seems unlikely that they were the result of the irradiation.

Basal Cell Carcinoma↗
PubMed1983

Metastability and polymorphism in the gel and fluid bilayer phases of dilauroylphosphatidylethanolamine. Two crystalline forms in excess water.

The phase behavior of 1,2-dilauroyl-sn-glycero-3-phosphoethanolamine (DLPE) in excess water has been studied by differential scanning calorimetry and x-ray diffraction. In addition to the usual gel phase L beta of lamellar periodicity 5.07 nm and the fluid bilayer phase L alpha of periodicity 4.5 nm, two distinct crystalline forms may also be spontaneously adopted. The L beta phase is only produced by cooling from L alpha and is metastable, relaxing to one of the crystalline forms on incubation. One crystalline polymorph, designated beta 2, has a lamellar periodicity of 4.55 nm and corresponds to the structure of DLPE crystallized from a variety of organic solvents. The other crystalline polymorph, designated beta 1, has a lamellar periodicity of 3.78 nm, which implies that in this form the hydrocarbon chains are tilted at approximately 40 degrees to the bilayer normal. The beta 2 polymorph is obtained on dispersing crystalline DLPE directly in water at T less than 43 degrees C, on incubation in the L alpha phase at 30 degrees C less than T less than 43 degrees C, or on heating the beta 1 form slowly to T greater than 35 degrees C. The beta 1 polymorph is obtained on incubating the L beta phase at T less than 30 degrees C. By calorimetry, the L beta phase undergoes an endothermic transition (delta H = 15.5 kJ X mol-1 (3.7 kcal X mol-1)) at 30.6 degrees C to the fluid bilayer phase L alpha. The beta 1 phase undergoes an endothermic transition (delta H congruent to 50 kJ X mol-1 (12 kcal X mol-1)) to L alpha at 35 degrees C. The beta 2 phase undergoes an endothermic transition (delta H = 57 kJ X mol-1 (13.7 kcal X mol-1)) to L alpha at 43 degrees C.

Drug Stability↗
PubMed1983

Case-control study of ocular hypertension.

A retrospective case-control study compared 100 ocular hypertensive patients with 100 ocular normotensive patients matched for sex and age. Interviews were conducted and charts were reviewed to explore demographic, personal, and environmental factors, as well as medical history and refractive error. Multiple logistic regression analyses assessed which factors were independently related to the presence or absence of ocular hypertension. The variables significantly associated with the presence of ocular hypertension were family history of glaucoma, myopic refractive error, absence of liquor intake, history of nonocular surgery, high income, and history of high BP.

Aged↗
PubMed1983

Ciliary body and choroidal melanomas treated by proton beam irradiation. Histopathologic study of eyes.

Proton beam irradiation resulted in clinical and/or histopathological regression of large ciliary body and choroidal melanomas in three eyes. Enucleations were performed 6 1/2 weeks, five months, and 11 months after irradiation for angle-closure glaucoma from total retinal detachment, increase in retinal detachment, and neovascular glaucoma, respectively. A direct relationship was found between the length of the interval from irradiation to enucleation and the degree of histologic changes. Vascular changes in the tumors included endothelial cell swelling and decreased lumen size, basement membrane thickening, collapse of sinusoidal vessels, and thrombosis of vessels. Although apparently unaltered tumor cells remained, degenerative changes occurred in some melanoma cells, including lipid vacuoles in cytoplasm, pyknotic nuclei, and balloon cell formation. Patchy areas of necrosis and proteinaceous exudate were present. Pigment-laden macrophages were found near tumor vessels and all had a substantial chronic inflammatory infiltrate. The effect of proton beam irradiation on tumor vessels probably plays an important role in uveal melanoma regression.

Adult↗
PubMed1983

A prognostic factor study of disease-free interval and survival following enucleation for uveal melanoma.

Prognostic indicators of uveal melanoma disease-free interval and survival following enucleation were evaluated for 267 patients. The median follow-up time was 17 years. Analysis involved Kaplan-Meier survival curves based on time to tumor-related deaths and multivariate proportional hazards analysis, which provides an estimate of the "force of mortality." Prognostic indicators considered included demographic, clinical, and histopathological factors. Cell type was classified according to the number of epithelioid cells present per high-power field (HPF) on light microscopy. Various classifications of size of the tumor were compared for prognostic value. The five leading predictors of survival in order of importance were as follows: (1) number of epithelioid cells per HPF, (2) largest dimension of the tumor, (3) location of the anterior margin of the tumor, (4) invasion to the line of transection, and (5) degree of pigmentation. Risk categories for survival were constructed based on the three leading prognostic factors.

Epithelium↗
PubMed1982

Gel-to-inverted hexagonal (L beta-HII) phase transitions in phosphatidylethanolamines and fatty acid-phosphatidylcholine mixtures, demonstrated by 31P-NMR spectroscopy and x-ray diffraction.

The phase behaviour of distearoyl- and dihexadecylphosphatidylethanolamine at high salt concentration and of dipalmitoylphosphatidylcholine + 66 mol% palmitic acid at pH 4.0 have been studied by high-field 31P-NMR spectroscopy and X-ray diffraction. In saturated NaCl, dihexadecylphosphatidylethanolamine undergoes a reversible transition at 74 degrees C directly from the lamellar gel phase L beta to the inverted hexagonal HII phase. A similar transition is observed at 78.4 degrees C for distearoylphosphatidylethanolamine in saturated NaCl (cooling scan). The single, sharp calorimetric transition at 61 degrees C observed in dipalmitoylphosphatidylcholine + 66 mol% palmitic acid at pH 4.0 also corresponds to a transformation directly from the lamellar gel to the inverted hexagonal phase, without an intervening fluid lamellar phase.

Calorimetry, Differential Scanning↗
PubMed1982

Uveal melanomas presenting during pregnancy and the investigation of oestrogen receptors in melanomas.

We observed a young woman who showed growth of a choroidal melanoma over the course of 2 pregnancies, with subsequent enucleation of the eye. This is the first such documented case. In addition 4 other women with uveal malignant melanomas presented during pregnancy. This observed number of pregnancies (5) was greater than the expected number (2.1) among women of childbearing age who underwent enucleation with subsequent analysis in our pathology laboratory. However, this difference was not statistically significant. Further, more females 44 years of age or younger underwent enucleation for malignant melanoma than men of comparable age. Evaluation of these cases led us to propose that there is a subset of patients whose ocular melanomas are hormonally responsive. We therefore analysed uveal melanoma and choroidal tissue from 7 patients, including one of the pregnant women, for the presence of oestrogen receptors. No specific oestrogen binding was found. The possibilities that other hormones are involved or an immunological mechanism is operative are discussed.

Adult↗
PubMed1982

Solitary extramedullary plasmacytoma of the palpebral conjunctiva.

A 63-year-old man had a solitary extramedullary plasmacytoma of the conjunctiva for several years with no history of ocular inflammation or systemic abnormalities. Immunoperoxidase staining was consistent with a neoplastic lesion. This is the only well documented such case in the recent literature to the best of our knowledge. This rare condition is contrasted with reactive plasma cell granuloma, a benign inflammatory condition, which comprises most of the cases previously reported as plasmacytomas. Since extraskeletal plasmacytomas may be the first manifestation of multiple myeloma, these patients deserve appropriate diagnostic evaluation and close follow-up.

Conjunctival Neoplasms↗
PubMed1981

Increased plasma cortisol levels in ocular hypertension.

Significant differences in plasma cortisol levels were found between patients with elevated ocular pressure and those with normal ocular pressure. The higher levels of plasma cortisol occurred in patients with higher ocular pressures. This significant separation was particularly related to the ocular pressure at the time of the plasma cortisol sampling; it was not related to other ocular factors or to systemic factors other than blood pressure (BP). Associated with the difference in levels of plasma cortisol was a significant difference in both systolic and diastolic BP between these two groups. Significant positive correlations were also found between plasma cortisol values and systolic BP and between ocular pressure and systolic BP. We concluded that an elevated plasma cortisol level is closely related to the pressure in the eye at the time of the cortisol sampling.

Adult↗
PubMed1980

Frequency of micturition and urinary tract infection.

Introital swabbing was done on each of 19 patients with a history of lower urinary tract infection. The swabs were collected during a 5-day period, with 2 swabs being collected each day. We found that 1) introital flora varied in nature and in number from hour to hour and from day to day, 2) repetitive qualitative swabbing was the most accurate method to determine the presence of pathogens in the introitus and 3) there was a relationship between the frequency of micturition and the presence of introital pathogens: a) normal controls became colonized with pathogens as frequency of voiding was increased and b) pathogen carriage was found more commonly in the patient group as compared to the controls and the patient group voided more frequently than the control group. The theoretical implications of this relationship are discussed.

Female↗
PubMed1978

Cystourethritis.

We believe this review lists the major factors and mechanisms considered responsible for producing cystourethritis. Knowledge of these factors and mechanisms is essential before effective investigation of this disease can be undertaken. We suggest a rational scheme for investigation of these patients. We believe successful treatment depends on establishing the probable cause in each individual patient. In view of the multifactorial etiology of the disease, attempts to find a single effective medical or surgical therapy will be doomed to failure.

Bacteriuria↗
PubMed1977

Intestinocystoplasty in treatment of interstitial cystitis.

Nine cases of interstitial cystitis treated by intestinocystoplasty are reviewed. The longest follow-up is seventy-eight months. Two patients have since died of unrelated causes. The results reveal seven symptomatic cures and two failures. Long-term renal and vesical function have been well maintained.

Adult↗
PubMed1977

Coagulum pyelolithotomy.

The interest shown in a coagulum pyelolithotomy technique reported at a recent urologic meeting has prompted this preliminary communication. It was not possible to follow the methodology recently reported using the fibrinogen preparation available in Canada. This led to the development of the simpler technique described in this report which has been used in 3 cases to date. In all cases all calculi were easily extracted. Using the coagulum, considerable operating room time was saved and renal instrumentation was minimized.

Coagulants↗
PubMed1976

Introital bacterial flora - effect of increased frequency of micturition.

Introital swabbing was performed on each of 20 premenopausal female volunteers over a 5-day period, 2 swabs being collected each day. During the last 3 days of the 5-day period the volunteers were requested to void every 2 hours. Analysis of our data shows: 1. Perineal bacterial flora varies in number and type of organisms from hour to hour and day to day. 2. Quantitative culturing is of little help in distinguishing colonisation of the introitus with urinary pathogens from mere intermittent contamination of the introitus with the same pathogens. 3. Our results suggest that 4 or more consecutive isolates of the potential urinary pathogens from the introitus over a 48-hour period signify colonisation. 4. Frequency of micturition increases the risk of colonisation of the introitus with potential urinary pathogens. The significance of these findings is discussed, in relation to the previous work of other investigators.

Adult↗