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Biomedical subjects

J R Gray

Publications and source records attributed to J R Gray.

45 records · Page 3Linked to original sources
PubMed1985

Design considerations for a fluorophotometer for ocular research.

Fluorometric studies have been made with modified slit-lamp microscopes. These instruments offered considerable versatility in modifying experimental parameters, but were seldom optimized in terms of detector and illuminator apertures, filter band-pass characteristics, detection system, light-source stabilization, or optical resolution. Improper control of these parameters can result in artifacts which override useful information. A new fluorophotometer for ocular research has been designed that utilizes an optical system, which eliminates the need for a contact lens. An effort was made to optimize both the axial resolution and the minimum detectable signal. The characteristics of standard barrier filters and excitation filters were examined and compared with photomultiplier sensitivity curves. It was necessary to use double filters in order to reduce artifacts due to excitation light that was not rejected by the barrier filter. In order to optimize the signal-to-noise ratio, a photon counting detection system was used. A dark current equivalent to 3 X 10(-10) g/ml allows a useful detection range of 1 X 10(-10) g/ml.

Anterior Chamber↗
PubMed1985

Optimized protocol for Fluorotron Master.

The technical aspects of fluorophotometry equipment are presented. The sources of artifact are described and a protocol to optimize the use of the "Coherent Fluorotron Master" system is presented. The results of fluorophotometry studies on ten patients indicate that more accurate data evaluation can be achieved using this approach.

Adult↗
PubMed1985

Characterization of the early stages of diabetic retinopathy by vitreous fluorophotometry.

We compared insulin-dependent diabetic patients with minimal (16 eyes of 9 patients) or no retinopathy (45 eyes of 27 patients) to normal volunteers (20 eyes of 12 subjects) using a commercial vitreous fluorophotometer and different procedures for artifact correction. The influence of background autofluorescence was minimized through the use of a software program that subtracted a fluorophotometric scan obtained before administration of fluorescein from that obtained after its injection. We also compared two programs designed to minimize the contribution of the chorioretinal peak spread function to the readings in the vitreous. The fluorescein concentration in the posterior vitreous was then averaged within two different regions. We then assessed the influence of these data-processing methods on the spread of the results of the different groups. The clinical study showed that only the posterior vitreous concentration of fluorescein is relevant in the evaluation of the blood-retinal barrier. However, since there is a gradient of fluorescein concentration in the posterior vitreous, one needs a scanning device so that one can measure at a precise location in front of the retina. The posterior vitreous concentration of fluorescein was significantly increased in diabetic subjects with one or no aneurysms as compared with normals. Moreover, the eyes with minimal retinopathy, as judged by the presence of microaneurysms, had higher values than those without retinopathy. The clear differences among these three groups were not present when the midvitreous values were used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Screening for familial ovarian cancer--management and outcome of women with moderate to high risk of developing ovarian cancer.

Five percent to ten percent of ovarian cancers are hereditary. Individual genetic risk of developing ovarian malignancy is discussed in women. Currently, prophylactic surgery is advised to women with a moderate to high risk of developing ovarian cancer. Workload and outcome of the multidisciplinary familial ovarian screening clinic in South Wales were assessed. This was an observational study of 145 women registered with the Familial Ovarian Screening Clinic between January 1998 and December 2003. The data were retrieved from the medical notes. Yearly follow-ups were investigated with a transvaginal scan and CA125 level. Post-surgery women were followed up with yearly CA125 estimations: 46.9% fell into moderate-risk and 50.3% into high-risk category. The median age was 42 (SD 10.4), 71.7% were pre menopausal, and 10.3% had a personal history of breast cancer and 1.4% colon cancer. Whereas 36.5% opted for surgery, the remaining women (but two) opted for annual follow-up. Histology of the women who had surgery showed three cases of malignancies (fallopian tube carcinoma, atypical ovarian epithelial cells, and metastatic breast cancer). Seven women developed breast cancer during the observation period. The follow-up period is too short to come to a final conclusion as to the benefits of yearly screening in this group of women. In our series, a significant number of patients developed malignancies, despite prophylactic surgery.

Adenocarcinoma↗
PubMedDate not supplied

Ocular fluorophotometric analysis.

Artifacts related to the wave-spreading phenomenon of fluorescent structures within the eye interfere with interpretation of vitreous fluorophotometric data. A standardized protocol which minimizes such artifacts is desirable in order to reveal actual changes in vitreous fluorescence. We have devised a protocol which reduces artifacts of crystalline lens autofluorescence and "tailing" from both lens and retina by the subtraction of preinjection data from measurements taken one hour after intravenous injection of fluorescein. A method of calculation is presented, performed automatically when programmed into a computerized fluorophotometer. Distinctions among healthy subjects and different kinds of ocular pathology are sharper when artifacts are reduced and the data are normalized to plasma fluorescein concentration. Examples of data from subjects with diabetes and no retinopathy, hypertension, cystoid macular edema, panuveitis and pars planitis are presented.

Diabetes Mellitus↗
PubMedDate not supplied

The tumor conference: an integral component of the oncology program.

This periodic meeting of individuals with oncologic expertise represents the best that modern medicine can be: a true multidisciplinary approach to patient care. Nowhere else in healthcare will you find a better example of combining different expertise for the express purpose of improving the delivery of care for an individual patient.

Education, Medical, Continuing↗
PubMedDate not supplied

Preoperative combined modality therapy with paclitaxel, carboplatin, prolonged infusion 5-fluorouracil, and radiation therapy in localized esophageal cancer: preliminary results of a Minnie Pearl Cancer Research Network phase II trial.

PURPOSE: To evaluate the feasibility, toxicity, and therapeutic efficacy of 1-hour paclitaxel, carboplatin, continuous low-dose infusional 5-fluorouracil, and concurrent radiation therapy administered preoperatively in patients with localized esophageal cancer. PATIENT AND METHODS: Forty-nine patients with localized esophageal cancer, of either squamous cell carcinoma or adenocarcinoma histology, were enrolled into this phase II trial. All patients were candidates for surgical resection and received the following neoadjuvant therapy: paclitaxel, 200 mg/m2, 1 hour IV on days 1 and 22; carboplatin, AUC 6.0, IV on days 1 and 22; 5-fluorouracil, 225 mg/m2/day, continuous IV infusion on days 1 to 42; and radiation therapy, 45 Gy, administered by 1.8-Gy daily fractions beginning on day 1 of chemotherapy. Upon completion of this neoadjuvant regimen, patients were reevaluated, and all responding patients were resected within 6 weeks of completing neoadjuvant treatment. RESULTS: Administration of this combined modality regimen was associated with moderate toxicity and was tolerated by most patients. Leukopenia (65%) and esophagitis (31%) were the most common toxicities. Most patients did not require nutritional support. There were no treatment-related deaths during neoadjuvant therapy; however, three patients (9%) experienced postoperative death. Preliminary assessment of treatment efficacy is encouraging, with 17 of 37 evaluable patients (46%) achieving pathologic complete remission and an additional 11 patients (30%) having only microscopic residual disease. CONCLUSIONS: This novel, combined-modality neoadjuvant approach for the treatment of localized esophageal carcinoma is feasible and can be administered with toxicity that compares favorably to previously reported neoadjuvant regimens containing high-dose cisplatin. Preliminary assessment of efficacy is also encouraging, with 46% of patients having pathologic complete response. Further follow-up and larger numbers of patients are required to assess efficacy more definitively.

Adenocarcinoma↗